Abstract:
An insulating polymer material composition is obtained by adequately adding a curing agent, a curing accelerator or the like to an epoxidized vegetable oil (such as an epoxidizable vegetable oil and fat which is an ester of glycerin and a fatty acid having a double bond portion therein), and heating and three-dimensionally crosslinking the resulting. As the curing agent, the curing accelerator or the like, those used for petroleum-derived polymer materials such as epoxy resins can be used. This polymer material composition is applied to, for example, insulating structures for high-voltage devices including a switching device such as a circuit breaker or disconnector in the casing.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to an insulating polymer material composition applied to, for example, an insulating structure for a high-voltage device comprising a switching device such as a circuit breaker or disconnector in the casing. 
         [0002]    As a material applied (for example, in such a manner as to be exposed directly to the outdoors) to an insulating structure (e.g. a portion which needs the insulating property) for a voltage device (such as a high-voltage device) comprising a switching device such as a circuit breaker or disconnector in the casing, a composition obtained by curing a polymer material containing a petroleum-derived thermosetting resin (i.e. a resin using petroleum as a starting material, such as epoxy resins or the like) as a main component, for example, a product (i.e. a molded product hereinafter referred to as a polymer product) comprising a composition formed by molding the polymer material have been conventionally and widely known. 
         [0003]    With sophistication and concentration of society, the high-voltage device and the like have been strongly desired, for example, to be reduced in size and grown in capacity while ensuring great reliability (e.g. mechanical properties and electrical properties). With this, the polymer product also has been required to improve in various properties. 
         [0004]    In general, examples of a main component of the polymer material used in conventionally known polymer products are: epoxy resins of heat resistant type having a glass transition temperature (hereinafter referred to as “Tg”) of not lower than 100° C.; bisphenol-A-type epoxy resins relatively high in mechanical properties (such as the strength); and the like. However, in consideration of disposal of the polymer product (for example, disposal due to lifespan or breakdown), a polymer product formed of a biodegradable polymer material has undergone development as discussed in Patent Document 1. 
         [0005]    As a result of having tried in various technical fields (e.g. in Patent Document 2) to apply a composition formed by curing a plant-derived polymer material (for example, to a printed-circuit board), there became known that sufficient mechanical properties can be obtained e.g. when the product is used in room temperature atmosphere. However, this composition is formed by using aldehydes as a curing agent, and therefore it had not been applied to the high-voltage device since poor in mechanical properties in a high temperature atmosphere. 
         [0006]    The above-discussed polymer product in which the heat resistant epoxy resins having a glass transition temperature (hereinafter referred to as “Tg”) of not lower than 100° C. are used as the main component of the polymer material is rigid and fragile, and additionally raises a fear that cracks are easily formed when the polymer product is used in an environment where temperature changes frequently. In view of this, there had been made some attempts, for example, to use solid epoxy resins (e.g. those in which a result of a crack resistance test using a metal conductor is not higher than −30° C.) as the main component of the polymer material or to improve a crack resistance and the like by adding a large quantity of filler to the polymer material; however, such a polymer product is significantly increased in viscosity, and therefore there is a fear that a pot life (the shortest possible time for an industrial operation) cannot be sufficiently ensured thereby reducing workability, e.g. in a molding operation. 
         [0007]    Though the above-discussed bisphenol-A-type epoxy resins are widely used as industrial products since they are high in mechanical properties, bisphenol A in itself is regarded as a deleterious endocrine disruptor and therefore it became concerned from the environmental point. Though there is a report that a cured composition such as the polymer product is not deleterious since bisphenol A is hard to leak out therefrom, bisphenol A is deleterious even in a very small quantity (for example, even at a ppm level or more smaller amount) and may leak into the air when unreacted bisphenol A (a low molecular-weight component) exists in the composition, which raises concern. 
         [0008]    In a limited environment, for example, in a process for synthesizing bisphenol-A-type epoxy resins and various additives or a process for molding a polymer material obtained by the synthesizing process at a polymer product production facility, there is a fear that the environment is in an atmosphere of a high concentration of bisphenol A. Further, this raises a fear of a production cost increase, since ventilation equipment (i.e. equipment for cleaning air in the work environment) is required in each of the above-discussed processes even if each of the above-discussed production processes is carried out completely without humans in attendance (or even if production lines for the polymer product are made unattended) or since ventilation equipment which had been out of assumption in conventional techniques becomes needed. 
         [0009]    In disposal of the polymer product (e.g. disposal due to lifespan or breakdown), various disposal methods can be employed; however, every one of the methods has problems as discussed below. 
         [0010]    For example, if an incineration treatment method is applied to the polymer product formed of the polymer material containing the petroleum-derived substance (such as epoxy resins) as the main component, various deleterious substances and carbon dioxide are emitted in large quantity thereby causing some issues such as environmental pollution and global warming, which had been the feared point. In addition, though a mere landfill method may be applied to the above-discussed polymer product, a final disposal field ensured for the landfill method is decreasing tendency through the years. The Ministry of Health and Welfare made a trial calculation of the remaining time to determine it to be about the year 2008. Then, the Economic Planning Agency gives an assumption, based on the trial calculation provided by the Ministry of Health and Welfare, that the waste-disposal cost will rocket up around 2008 thereby depressing the economic growth rate. 
         [0011]    Additionally, though an attempt to recall and reuse (recycle) the above-discussed polymer product is also carried out, such a recycling method is not established and therefore hardly carried out. By way of exception, components relatively equal in quality (PE cable-coating members used in the polymer product) are recalled to be used as thermal energy; however, thermal energy requires a combustion treatment process so as to sometimes cause the issues of environmental pollution, global warming and the like. 
         [0012]    However, there is a fear also in the case where the polymer product is formed of the biodegradable polymer material, the fear being that the polymer product is melted when used in an atmosphere, for example, at temperature of not lower than 100° C.. Further, in the case where the polymer product is formed of a crosslinking composition of biological origin and uses aldehydes as the curing agent, sufficient mechanical properties may be not obtained in a high temperature atmosphere (e.g. in the work environment for high-voltage devices or the like), though obtained in an atmosphere of about room temperature (e.g. in an environment for the printed-circuit board in terms of temperature). 
         [0013]    In view of the above, it is required to improve various problems relating to the disposal of such polymer products while keeping their properties (such as the mechanical properties and the electrical properties) excellent. 
         [0014]    Patent Document 1: Japanese Patent Provisional Publication No. 2002-358829 
         [0015]    Patent Document 2: Japanese Patent Provisional Publication No. 2002-053699 
       SUMMARY OF THE INVENTION 
       [0016]    It is, therefore, an object to provide an insulating polymer material composition which is environmentally excellent and able to impart sufficient properties (for example, mechanical properties and electrical properties) to a polymer product such as the high-voltage device without reducing the workability. 
         [0017]    An aspect of the present invention resides in an insulating polymer material composition applied to an insulating structure for a voltage device. The insulating polymer material composition of the present invention comprises a polymer material containing a vegetable oil as a main component and three-dimensionally crosslinked with heat. 
         [0018]    A further aspect of the present invention resides in an insulating polymer material composition as discussed above, wherein the vegetable oil is epoxidized. 
         [0019]    A still further aspect of the present invention resides in an insulating polymer material composition as discussed above, wherein a curing agent is added to the polymer material. 
         [0020]    By using vegetable oil as the main component of the polymer material as discussed above, the electrical properties (such as the insulating property) and the mechanical properties (such as the tensile strength) are sufficiently obtained (or obtained at least equally to a case where a bisphenol-A-type epoxy resin is used in the polymer material composition) even if the filler is not such a large quantity as to be used in conventional polymer products, since the vegetable oil is an ester of glycerin and a fatty acid having a sufficient molecular length. 
         [0021]    The above-discussed polymer material composition generates neither deleterious substances nor carbon dioxide even if incinerated, and additionally is biodegradable when landfilled in soil. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0022]    Hereinafter, an embodiment of an insulating polymer material composition according to the present invention will be discussed in detail. 
         [0023]    In this embodiment, a polymer material naturally originated and capable of three-dimensionally crosslinking is used in place of a petroleum-derived polymer material such as epoxy resins, in an insulating polymer material composition applied to a portion of a polymer product requiring an insulating property. 
         [0024]    More specifically, the polymer material as discussed above is found to be able to ensure sufficiently excellent electrical and mechanical properties and therefore to be applied to a high-voltage device. Further, since the polymer material in itself is neutral toward carbon, a composition (e.g. a polymer product) formed of the polymer material is found to be able to prevent or suppress the emission of deleterious substances (such as endocrine disruptor) and carbon dioxide and the like even if subjected to an incineration treatment, and additionally found to be biodegradable, for example, when landfilled in soil. The naturally originated polymer material is known to be applied to a printed-circuit board; however, it has never been applied to the high-voltage device. 
         [0025]    Examples of the polymer material naturally originated and capable of three-dimensionally crosslinking as discussed above are epoxidizable (modifiable) ones having a reactive portion in its chain, such as epoxidizable vegetable oils and fats which are esters of glycerin and a fatty acid having a double bond portion therein. 
         [0026]    Concrete examples of the vegetable oils epoxidizable and applicable to the present invention are vegetable oils whose components are unsaturated fatty acids (e.g. linoleic acid, linolenic acid and oleic acid), such as perilla oil, linseed oil, tung oil, poppy oil, walnut oil, safflower oil, sunflower seed oil, rape oil, corn oil, cottonseed oil, soybean oil, sesame oil, rice oil and olive oil. Additionally, a mixture of two or more kinds of these vegetable oils may be applied to the present invention. 
         [0027]    Therefore, vegetable oils epoxidized according to the present embodiment can impart sufficient properties (for example, mechanical properties and electrical properties) and environmental properties to the polymer product such as the high-voltage device without reducing the workability, and are not limited in, for example, kind and process (i.e. process relating to vegetable oil, such as picking, expression, extraction, refinement, degumming, deoxidation, decolorization, dewaxing and deodorization). 
         [0028]    The above-discussed epoxidation is achieved by: epoxide synthesis using hydrogen peroxide (or a synthesis for epoxidizing an unsaturated bond portion in lignin); photooxidation; glycidyl-etherification (glycidyl-etherification with epihalohydrin); or the like. 
         [0029]    The insulating polymer material composition is obtained by curing the epoxidized vegetable oils with heat (for example, by three-dimensionally crosslinking the epoxidized vegetable oils). At the time of the curing with heat, various curing agents may be suitably used in accordance with demand. As the curing agents, it may be possible to variously apply those who can cure the epoxidized vegetable oils with heat (or can three-dimensionally crosslink the epoxidized vegetable oils), and more specifically, those used in the petroleum-derived polymer material such as epoxy resins. In other words, the curing agent used in the present embodiment is not limited to the above-mentioned one. 
         [0030]    Concrete examples of the curing agent are: polyamines (such as diethylenetriamine, isophorone diamine, diaminodiphenylmethane, diamine diamide, polyamide, polyamine modified with epoxide, and ketimine); acid anhydrides (such as dodecenylsuccinic anhydride, methylnadic anhydride, trimellitic anhydride, pyromelletic dianhydride); novolac-type phenol resins; phenolic polymers; polysulfides; polyester resins containing carboxylic acids; tertiary amines (such as benzyl methyl); imidazoles (such as 2-methyl imidazole); Lewis acids (such as BF 3  monoethylamine and BF 3  piperazine); aromatic sulfonium salts; aromatic diazonium salts; resol-type phenol resins; melamine resins having a methylol group. 
         [0031]    Further, various curing accelerators may be suitably used in accordance with demand at the time of the curing with heat, for the purposes of improving a Tg propery, mechanical and electrical properties, temperature dependence of these properties, and workability (e.g. shortening of operation time), and of decreasing a temperature at which the curing with heat is accomplished. The curing accelerators may be those used in the petroleum-derived polymer material such as epoxy resins and are not particularly limited. 
       Examples  
       [0032]    The insulating polymer material composition of the present embodiment will be more readily understood with reference to the following Examples. First of all, an epoxidized linseed oil (available from DAICEL CHEMICAL INDUSTRIES, LTD. under the trade name of L-500 (CAS8016-11-3)) was prepared as a vegetable oil. Each curing agent as shown in the following Tables 1 and 2 was added to the epoxidized linseed oil in a certain amount (or in a stoichiometric amount) and then heated under its own conditions (such as curing temperature and curing time) to be cured (or to be three-dimensionally crosslinked), thereby obtaining insulating polymer material composition specimens S1 to S42 each. 
         [0000]    
       
         
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
             
             
               
                   
                   
                 Specimen S1 
                 Specimen S2 
                 Specimen S3 
                 Specimen S4 
                 Specimen S5 
                 Specimen S6 
                 Specimen S7 
               
               
                   
               
               
                 Curing 
                 Kind 
                 Diethylene- 
                 Triethylene 
                 Diethylamino 
                 Methaxylylene 
                 Menthenediamine 
                 Aminoethyl 
                 Heterocyclic 
               
               
                 agent 
                   
                 triamine 
                 tetramine 
                 propylamine 
                 diamine 
                   
                 piperazine 
                 diamine 
               
               
                   
                 Added 
                 11 
                 12 
                 7 
                 19 
                 17 
                 22 
                 56 
               
               
                   
                 amount 
               
               
                   
                 (phr) 
               
               
                 Curing 
                 Curing 
                 100 
                 100 
                 70 
                 70 
                 80 
                 200 
                 60 
               
               
                 condition 
                 temperature 
               
               
                   
                 (° C.) 
               
               
                   
                 Curing time 
                 2 
                 2 
                 4 
                 2 
                 2 
                 1 
                 4 
               
               
                   
                 (h) 
               
               
                   
               
               
                   
                   
                 Specimen S8 
                 Specimen S9 
                 Specimen S10 
                 Specimen S11 
                 Specimen S12 
                 Specimen S13 
                 Specimen S14 
               
               
                   
               
               
                 Curing 
                 Kind 
                 Bis(4-amino-3- 
                 Meta 
                 Benzyldimethyl 
                 Diaminodiphenyl 
                 Dicyandiamide 
                 Methylene- 
                 Di- 
               
               
                 agent 
                   
                 methyl- 
                 phenylene 
                 amine 
                 methane 
                   
                 dianiline 
                 aminodiphenyl 
               
               
                   
                   
                 cyclohexyl)- 
                 diamine 
                   
                   
                   
                   
                 sulfone 
               
               
                   
                   
                 methane 
               
               
                   
                 Added 
                 39 
                 17 
                 11 
                 31 
                 7 
                 31 
                 45 
               
               
                   
                 amount 
               
               
                   
                 (phr) 
               
               
                 Curing 
                 Curing 
                 150 
                 150 
                 100 
                 170 
                 170 
                 150 
                 200 
               
               
                 condition 
                 temperature 
               
               
                   
                 (° C.) 
               
               
                   
                 Curing time 
                 4 
                 4 
                 12 
                 5 
                 3 
                 4 
                 4 
               
               
                   
                 (h) 
               
               
                   
               
               
                   
                   
                 Specimen S15 
                 Specimen S16 
                 Specimen S17 
                 Specimen S18 
                 Specimen S19 
                 Specimen S20 
                 Specimen S21 
               
               
                   
               
               
                 Curing 
                 Kind 
                 Phthalic 
                 Hexa- 
                 Methylnadic 
                 Dodecylsuccinic 
                 Chlorendic 
                 Polyamide 
                 Piperidine 
               
               
                 agent 
                   
                 anhydride 
                 hydrophthalic 
                 anhydride 
                 anhydride 
                 anhydride 
                 resin dimer 
               
               
                   
                   
                   
                 anhydride 
                   
                   
                   
                 acid/ 
               
               
                   
                   
                   
                   
                   
                   
                   
                 diethylene- 
               
               
                   
                   
                   
                   
                   
                   
                   
                 triamine 
               
               
                   
                 Added 
                 49 
                 45 
                 90 
                 145 
                 123 
                 112 
                 7 
               
               
                   
                 amount 
               
               
                   
                 (phr) 
               
               
                 Curing 
                 Curing 
                 150 
                 150 
                 150 
                 150 
                 200 
                 60 
                 60 
               
               
                 condition 
                 temperature 
               
               
                   
                 (° C.) 
               
               
                   
                 Curing time 
                 8 
                 24 
                 24 
                 24 
                 2 
                 24 
                 24 
               
               
                   
                 (h) 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
             
             
               
                   
                   
                 Specimen S22 
                 Specimen S23 
                 Specimen S24 
                 Specimen S25 
                 Specimen S26 
                 Specimen S27 
                 Specimen S28 
               
               
                   
               
               
                 Curing 
                 Kind 
                 Dimethyl- 
                 Tris(dimethyl- 
                 Trimellitic 
                 Pyromelletic 
                 2-Ethyl-4- 
                 BF 3 - 
                 BF 3 -triethylamine 
               
               
                 agent 
                   
                 aminomethyl- 
                 aminomethyl)- 
                 anhydride 
                 dianhydride 
                 methylimidazole 
                 monomethyl- 
               
               
                   
                   
                 phenol 
                 phenol 
                   
                   
                   
                 amine 
               
               
                   
                   
                 (DMP-10) 
                 (DMP-30) 
               
               
                   
                 Added 
                 6 
                 6 
                 112 
                 112 
                 2 
                 3 
                 34 
               
               
                   
                 amount 
               
               
                   
                 (phr) 
               
               
                 Curing 
                 Curing 
                 60 
                 200 
                 60 
                 100 
                 60 
                 120 
                 170 
               
               
                 condition 
                 temperature 
               
               
                   
                 (° C.) 
               
               
                   
                 Curing time 
                 24 
                 2 
                 24 
                 15 
                 8 
                 3 
                 5 
               
               
                   
                 (h) 
               
               
                   
               
               
                   
                   
                 Specimen S29 
                 Specimen S30 
                 Specimen S31 
                 Specimen S32 
                 Specimen S33 
                 Specimen S34 
                 Specimen S35 
               
               
                   
               
               
                 Curing 
                 Kind 
                 BF 3 -piperidine 
                 BF 3 -aniline 
                 Phenol resin 
                 Urea resin 
                 Melamine resin 
                 Aniline resin 
                 1- 
               
               
                 agent 
                   
                   
                   
                   
                   
                   
                   
                 Penta- 
               
               
                   
                   
                   
                   
                   
                   
                   
                   
                 chlorophenyl 
               
               
                   
                   
                   
                   
                   
                   
                   
                   
                 diethylene- 
               
               
                   
                   
                   
                   
                   
                   
                   
                   
                 triamine 
               
               
                   
                 Added 
                 34 
                 11 
                 — 
                 — 
                 112 
                 112 
                 112 
               
               
                   
                 amount 
               
               
                   
                 (phr) 
               
               
                 Curing 
                 Curing 
                 190 
                 40 
                 150 
                 150 
                 150 
                 120 
                 200 
               
               
                 condition 
                 temperature 
               
               
                   
                 (° C.) 
               
               
                   
                 Curing time 
                 10 
                 4 
                 4 
                 8 
                 8 
                 16 
                 4 
               
               
                   
                 (h) 
               
               
                   
               
               
                   
                   
                 Specimen S36 
                 Specimen S37 
                 Specimen S38 
                 Specimen S39 
                 Specimen S40 
                 Specimen S41 
                 Specimen S42 
               
               
                   
               
               
                 Curing 
                 Kind 
                 N,N- 
                 1,1- 
                 Dicyandiamide 
                 Tris(alkylamino)- 
                 Menthanediamine 
                 Xylenediamine 
                 Dichlorosuccinic 
               
               
                 agent 
                   
                 (Hexachloro- 
                 (Hexachloro- 
                   
                 silane 
                   
                   
                 anhydride 
               
               
                   
                   
                 biphenylylene)- 
                 biphenylylene)- 
               
               
                   
                   
                 bis(diethylene- 
                 bis(diethylene- 
               
               
                   
                   
                 triamine) 
                 triamine) 
               
               
                   
                 Added 
                 112 
                 168 
                 7 
                 25 
                 25 
                 18 
                 42 
               
               
                   
                 amount 
               
               
                   
                 (phr) 
               
               
                 Curing 
                 Curing 
                 200 
                 200 
                 150 
                 150 
                 180 
                 70 
                 120 
               
               
                 condition 
                 temperature 
               
               
                   
                 (° C.) 
               
               
                   
                 Curing time 
                 4 
                 4 
                 8 
                 8 
                 3 
                 1 
                 2 
               
               
                   
                 (h) 
               
               
                   
               
             
          
         
       
     
         [0033]    On the other hand, an epoxidized soybean oil (available from DAICEL CHEMICAL INDUSTRIES, LTD. under the trade name of S-300K (CAS8013-07-8)) was prepared in place of the above-discussed epoxidized linseed oil. Each curing agent as shown in the following Tables 3 and 4 (or each of the same curing agents as shown in Tables 1 and 2) was added to the epoxidized soybean oil in a certain amount (or in a stoichiometric amount) and then heated under its own conditions (such as curing temperature and curing time) to be cured (or to be three-dimensionally crosslinked), thereby obtaining insulating polymer material composition specimens T1 to T42 each. 
         [0000]    
       
         
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 3 
               
               
                   
               
             
             
               
                   
                   
                 Specimen T1 
                 Specimen T2 
                 Specimen T3 
                 Specimen T4 
                 Specimen T5 
                 Specimen T6 
                 Specimen T7 
               
               
                   
               
               
                 Curing 
                 Kind 
                 Diethylene- 
                 Triethylene 
                 Diethylamino 
                 Methaxylylene 
                 Menthenediamine 
                 Aminoethyl 
                 Heterocyclic 
               
               
                 agent 
                   
                 triamine 
                 tetramine 
                 propylamine 
                 diamine 
                   
                 piperazine 
                 diamine 
               
               
                   
                 Added 
                 8 
                 8 
                 5 
                 13 
                 11 
                 15 
                 38 
               
               
                   
                 amount 
               
               
                   
                 (phr) 
               
               
                 Curing 
                 Curing 
                 100 
                 100 
                 70 
                 70 
                 80 
                 200 
                 60 
               
               
                 condition 
                 temperature 
               
               
                   
                 (° C.) 
               
               
                   
                 Curing time 
                 2 
                 2 
                 4 
                 2 
                 2 
                 1 
                 4 
               
               
                   
                 (h) 
               
               
                   
               
               
                   
                   
                 Specimen T8 
                 Specimen T9 
                 Specimen T10 
                 Specimen T11 
                 Specimen T12 
                 Specimen T13 
                 Specimen T14 
               
               
                   
               
               
                 Curing 
                 Kind 
                 Bis(4-amino-3- 
                 Meta 
                 Benzyldimethyl 
                 Diaminodiphenyl 
                 Dicyandiamide 
                 Methylene- 
                 Di- 
               
               
                 agent 
                   
                 methyl- 
                 phenylene 
                 amine 
                 methane 
                   
                 dianiline 
                 aminodiphenyl 
               
               
                   
                   
                 cyclohexyl)- 
                 diamine 
                   
                   
                   
                   
                 sulfone 
               
               
                   
                   
                 methane 
               
               
                   
                 Added 
                 27 
                 11 
                 8 
                 21 
                 5 
                 21 
                 30 
               
               
                   
                 amount 
               
               
                   
                 (phr) 
               
               
                 Curing 
                 Curing 
                 150 
                 150 
                 100 
                 170 
                 170 
                 150 
                 200 
               
               
                 condition 
                 temperature 
               
               
                   
                 (° C.) 
               
               
                   
                 Curing time 
                 4 
                 4 
                 12 
                 5 
                 3 
                 4 
                 4 
               
               
                   
                 (h) 
               
               
                   
               
               
                   
                   
                 Specimen T15 
                 Specimen T16 
                 Specimen T17 
                 Specimen T18 
                 Specimen T19 
                 Specimen T20 
                 Specimen T21 
               
               
                   
               
               
                 Curing 
                 Kind 
                 Phthalic 
                 Hexa- 
                 Methylnadic 
                 Dodecylsuccinic 
                 Chlorendic 
                 Polyamide 
                 Piperidine 
               
               
                 agent 
                   
                 anhydride 
                 hydrophthalic 
                 anhydride 
                 anhydride 
                 anhydride 
                 resin 
               
               
                   
                   
                   
                 anhydride 
                   
                   
                   
                 dimer acid/ 
               
               
                   
                   
                   
                   
                   
                   
                   
                 diethylene- 
               
               
                   
                   
                   
                   
                   
                   
                   
                 triamine 
               
               
                   
                 Added 
                 33 
                 30 
                 60 
                 100 
                 85 
                 76 
                 5 
               
               
                   
                 amount 
               
               
                   
                 (phr) 
               
               
                 Curing 
                 Curing 
                 150 
                 150 
                 150 
                 150 
                 200 
                 60 
                 60 
               
               
                 condition 
                 temperature 
               
               
                   
                 (° C.) 
               
               
                   
                 Curing time 
                 8 
                 24 
                 24 
                 24 
                 2 
                 24 
                 24 
               
               
                   
                 (h) 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 4 
               
               
                   
               
             
             
               
                   
                   
                 Specimen T22 
                 Specimen T23 
                 Specimen T24 
                 Specimen T25 
                 Specimen T26 
                 Specimen T27 
                 Specimen T28 
               
               
                   
               
               
                 Curing 
                 Kind 
                 Dimethyl- 
                 Tris(dimethyl- 
                 Trimellitic 
                 Pyromelletic 
                 2-Ethyl-4- 
                 BF 3 - 
                 BF 3 -triethylamine 
               
               
                 agent 
                   
                 aminomethyl- 
                 aminomethyl)- 
                 anhydride 
                 dianhydride 
                 methylimidazole 
                 monomethyl- 
               
               
                   
                   
                 phenol 
                 phenol 
                   
                   
                   
                 amine 
               
               
                   
                   
                 (DMP-10) 
                 (DMP-30) 
               
               
                   
                 Added 
                 4 
                 4 
                 76 
                 76 
                 2 
                 2 
                 23 
               
               
                   
                 amount 
               
               
                   
                 (phr) 
               
               
                 Curing 
                 Curing 
                 60 
                 200 
                 60 
                 100 
                 60 
                 120 
                 170 
               
               
                 condition 
                 temperature 
               
               
                   
                 (° C.) 
               
               
                   
                 Curing time 
                 4 
                 2 
                 24 
                 15 
                 8 
                 3 
                 5 
               
               
                   
                 (h) 
               
               
                   
               
               
                   
                   
                 Specimen T29 
                 Specimen T30 
                 Specimen T31 
                 Specimen T32 
                 Specimen T33 
                 Specimen T34 
                 Specimen T35 
               
               
                   
               
               
                 Curing 
                 Kind 
                 BF 3 -piperidine 
                 BF 3 -aniline 
                 Phenol resin 
                 Urea resin 
                 Melamine resin 
                 Aniline resin 
                 1- 
               
               
                 agent 
                   
                   
                   
                   
                   
                   
                   
                 Penta- 
               
               
                   
                   
                   
                   
                   
                   
                   
                   
                 chlorophenyl 
               
               
                   
                   
                   
                   
                   
                   
                   
                   
                 diethylene- 
               
               
                   
                   
                   
                   
                   
                   
                   
                   
                 triamine 
               
               
                   
                 Added 
                 23 
                 8 
                 — 
                 — 
                 76 
                 76 
                 76 
               
               
                   
                 amount 
               
               
                   
                 (phr) 
               
               
                 Curing 
                 Curing 
                 190 
                 40 
                 150 
                 150 
                 150 
                 120 
                 200 
               
               
                 condition 
                 temperature 
               
               
                   
                 (° C.) 
               
               
                   
                 Curing time 
                 10 
                 4 
                 4 
                 8 
                 8 
                 16 
                 4 
               
               
                   
                 (h) 
               
               
                   
               
               
                   
                   
                 Specimen T36 
                 Specimen T37 
                 Specimen T38 
                 Specimen T39 
                 Specimen T40 
                 Specimen T41 
                 Specimen T42 
               
               
                   
               
               
                 Curing 
                 Kind 
                 N,N- 
                 1,1- 
                 Dicyandiamide 
                 Tris(alkylamino)- 
                 Menthanediamine 
                 Xylenediamine 
                 Dichlorosuccinic 
               
               
                 agent 
                   
                 (Hexachloro- 
                 (Hexachloro- 
                   
                 silane 
                   
                   
                 anhydride 
               
               
                   
                   
                 biphenylylene)- 
                 biphenylylene)- 
               
               
                   
                   
                 bis(diethylene- 
                 bis(diethylene- 
               
               
                   
                   
                 triamine) 
                 triamine) 
               
               
                   
                 Added 
                 76 
                 114 
                 5 
                 17 
                 17 
                 12 
                 30 
               
               
                   
                 amount 
               
               
                   
                 (phr) 
               
               
                 Curing 
                 Curing 
                 200 
                 200 
                 150 
                 150 
                 180 
                 70 
                 120 
               
               
                 condition 
                 temperature 
               
               
                   
                 (° C.) 
               
               
                   
                 Curing time 
                 4 
                 4 
                 8 
                 8 
                 3 
                 1 
                 2 
               
               
                   
                 (h) 
               
               
                   
               
             
          
         
       
     
         [0034]    Furthermore, any one of curing agents as shown in the following Tables 5 and 6 (or any one of the same curing agents as shown in Tables 1 and 2) was added to a bisphenol-A-type epoxy resin (having an epoxy equivalent weight of about 190) in a certain amount (or in a stoichiometric amount) and then heated under its own conditions (such as curing temperature and curing time) to be cured (or to be three-dimensionally crosslinked), thereby obtaining insulating polymer material composition specimens P1 to P42 each. 
         [0000]    
       
         
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 5 
               
               
                   
               
             
             
               
                   
                   
                 Specimen P1 
                 Specimen P2 
                 Specimen P3 
                 Specimen P4 
                 Specimen P5 
                 Specimen P6 
                 Specimen P7 
               
               
                   
               
               
                 Curing 
                 Kind 
                 Diethylene- 
                 Triethylene 
                 Diethylamino 
                 Methaxylylene 
                 Menthenediamine 
                 Aminoethyl 
                 Heterocyclic 
               
               
                 agent 
                   
                 triamine 
                 tetramine 
                 propylamine 
                 diamine 
                   
                 piperazine 
                 diamine 
               
               
                   
                 Added 
                 10 
                 11 
                 6 
                 17 
                 15 
                 20 
                 50 
               
               
                   
                 amount 
               
               
                   
                 (phr) 
               
               
                 Curing 
                 Curing 
                 100 
                 100 
                 70 
                 70 
                 80 
                 200 
                 60 
               
               
                 condition 
                 temperature 
               
               
                   
                 (° C.) 
               
               
                   
                 Curing time 
                 2 
                 2 
                 4 
                 2 
                 2 
                 1 
                 4 
               
               
                   
                 (h) 
               
               
                   
               
               
                   
                   
                 Specimen P8 
                 Specimen P9 
                 Specimen P10 
                 Specimen P11 
                 Specimen P12 
                 Specimen P13 
                 Specimen P14 
               
               
                   
               
               
                 Curing 
                 Kind 
                 Bis(4-amino-3- 
                 Meta 
                 Benzyldimethyl 
                 Diaminodiphenyl 
                 Dicyandiamide 
                 Methylene- 
                 Di- 
               
               
                 agent 
                   
                 methyl- 
                 phenylene 
                 amine 
                 methane 
                   
                 dianiline 
                 aminodiphenyl 
               
               
                   
                   
                 cyclohexyl)- 
                 diamine 
                   
                   
                   
                   
                 sulfone 
               
               
                   
                   
                 methane 
               
               
                   
                 Added 
                 35 
                 15 
                 10 
                 28 
                 6 
                 28 
                 40 
               
               
                   
                 amount 
               
               
                   
                 (phr) 
               
               
                 Curing 
                 Curing 
                 150 
                 150 
                 100 
                 170 
                 170 
                 150 
                 200 
               
               
                 condition 
                 temperature 
               
               
                   
                 (° C.) 
               
               
                   
                 Curing time 
                 4 
                 4 
                 12 
                 5 
                 3 
                 4 
                 4 
               
               
                   
                 (h) 
               
               
                   
               
               
                   
                   
                 Specimen P15 
                 Specimen P16 
                 Specimen P17 
                 Specimen P18 
                 Specimen P19 
                 Specimen P20 
                 Specimen P21 
               
               
                   
               
               
                 Curing 
                 Kind 
                 Phthalic 
                 Hexa- 
                 Methylnadic 
                 Dodecylsuccinic 
                 Chlorendic 
                 Polyamide 
                 Piperidine 
               
               
                 agent 
                   
                 anhydride 
                 hydrophthalic 
                 anhydride 
                 anhydride 
                 anhydride 
                 resin 
               
               
                   
                   
                   
                 anhydride 
                   
                   
                   
                 dimer acid/ 
               
               
                   
                   
                   
                   
                   
                   
                   
                 diethylene- 
               
               
                   
                   
                   
                   
                   
                   
                   
                 triamine 
               
               
                   
                 Added 
                 44 
                 40 
                 80 
                 130 
                 110 
                 100 
                 6 
               
               
                   
                 amount 
               
               
                   
                 (phr) 
               
               
                 Curing 
                 Curing 
                 150 
                 150 
                 150 
                 150 
                 200 
                 60 
                 60 
               
               
                 condition 
                 temperature 
               
               
                   
                 (° C.) 
               
               
                   
                 Curing time 
                 8 
                 24 
                 24 
                 24 
                 2 
                 24 
                 24 
               
               
                   
                 (h) 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 6 
               
               
                   
               
             
             
               
                   
                   
                 Specimen P22 
                 Specimen P23 
                 Specimen P24 
                 Specimen P25 
                 Specimen P26 
                 Specimen P27 
                 Specimen P28 
               
               
                   
               
               
                 Curing 
                 Kind 
                 Dimethyl- 
                 Tris(dimethyl- 
                 Trimellitic 
                 Pyromelletic 
                 2-Ethyl-4- 
                 BF 3 - 
                 BF 3 -triethylamine 
               
               
                 agent 
                   
                 aminomethyl- 
                 aminomethyl)- 
                 anhydride 
                 dianhydride 
                 methylimidazole 
                 monomethyl- 
               
               
                   
                   
                 phenol 
                 phenol 
                   
                   
                   
                 amine 
               
               
                   
                   
                 (DMP-10) 
                 (DMP-30) 
               
               
                   
                 Added 
                 5 
                 5 
                 100 
                 100 
                 2 
                 3 
                 30 
               
               
                   
                 amount 
               
               
                   
                 (phr) 
               
               
                 Curing 
                 Curing 
                 60 
                 200 
                 60 
                 100 
                 60 
                 120 
                 170 
               
               
                 condition 
                 temperature 
               
               
                   
                 (° C.) 
               
               
                   
                 Curing time 
                 24 
                 2 
                 24 
                 15 
                 8 
                 3 
                 5 
               
               
                   
                 (h) 
               
               
                   
               
               
                   
                   
                 Specimen P29 
                 Specimen P30 
                 Specimen P31 
                 Specimen P32 
                 Specimen P33 
                 Specimen P34 
                 Specimen P35 
               
               
                   
               
               
                 Curing 
                 Kind 
                 BF 3 -piperidine 
                 BF 3 -aniline 
                 Phenol resin 
                 Urea resin 
                 Melamine resin 
                 Aniline resin 
                 1- 
               
               
                 agent 
                   
                   
                   
                   
                   
                   
                   
                 Penta- 
               
               
                   
                   
                   
                   
                   
                   
                   
                   
                 chlorophenyl 
               
               
                   
                   
                   
                   
                   
                   
                   
                   
                 diethylene- 
               
               
                   
                   
                   
                   
                   
                   
                   
                   
                 triamine 
               
               
                   
                 Added 
                 30 
                 10 
                 100 
                 100 
                 100 
                 100 
                 100 
               
               
                   
                 amount 
               
               
                   
                 (phr) 
               
               
                 Curing 
                 Curing 
                 190 
                 40 
                 150 
                 150 
                 150 
                 120 
                 200 
               
               
                 condition 
                 temperature 
               
               
                   
                 (° C.) 
               
               
                   
                 Curing time 
                 10 
                 4 
                 4 
                 8 
                 8 
                 16 
                 4 
               
               
                   
                 (h) 
               
               
                   
               
               
                   
                   
                 Specimen P36 
                 Specimen P37 
                 Specimen P38 
                 Specimen P39 
                 Specimen P40 
                 Specimen P41 
                 Specimen P42 
               
               
                   
               
               
                 Curing 
                 Kind 
                 N,N- 
                 1,1- 
                 Dicyandiamide 
                 Tris(alkylamino)- 
                 Menthanediamine 
                 Xylenediamine 
                 Dichlorosuccinic 
               
               
                 agent 
                   
                 (Hexachloro- 
                 (Hexachloro- 
                   
                 silane 
                   
                   
                 anhydride 
               
               
                   
                   
                 biphenylylene)- 
                 biphenylylene)- 
               
               
                   
                   
                 bis(diethylene- 
                 bis(diethylene- 
               
               
                   
                   
                 triamine) 
                 triamine) 
               
               
                   
                 Added 
                 100 
                 150 
                 6 
                 22 
                 22 
                 16 
                 38 
               
               
                   
                 amount 
               
               
                   
                 (phr) 
               
               
                 Curing 
                 Curing 
                 200 
                 200 
                 150 
                 150 
                 180 
                 70 
                 120 
               
               
                 condition 
                 temperature 
               
               
                   
                 (° C.) 
               
               
                   
                 Curing time 
                 4 
                 4 
                 8 
                 8 
                 3 
                 1 
                 2 
               
               
                   
                 (h) 
               
               
                   
               
             
          
         
       
     
         [0035]    Then, each of the insulating polymer material composition specimens S1 to S42, T1 to T42 and P1 to P42 was measured in terms of: the volume resistivity as an electrical property (the insulating property); the tensile strength and tensile strain as mechanical properties (more specifically, as a property of a support structure applied to a polymer product and as the heat resistant stress against an embedded metal, respectively); and a strength value after each specimen had been embedded in soil for a certain period of time (hereinafter referred to as “a posterior strength value”), as the biodegradability. The thus obtained results are shown in the following Tables 7 to 12. 
         [0036]    The rate of change of the posterior strength value, as shown in the following Tables 8 to 12, was determined as follows. First of all, No. 1-type test pieces (or test pieces having a thickness of 0.5 mm) were respectively prepared according to JIS K 7113 from the insulating polymer material composition specimens S1 to S42, T1 to T42 and P1 to P42, and then embedded in soil in a laboratory container (in an atmosphere of 30° C. and 80% RH). Upon setting the specimens aside for 6 months, the posterior strength value was measured and compared with an initial value (or a tensile strength value before embedment in soil), thereby obtaining the rate of change (or the percentage of change where the initial value was defined as 100%). 
         [0000]    
       
         
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 7 
               
               
                   
               
             
             
               
                   
                   
                 Specimen S1 
                 Specimen S2 
                 Specimen S3 
                 Specimen S4 
                 Specimen S5 
                 Specimen S6 
                 Specimen S7 
               
               
                   
               
               
                 Electrical 
                 Volume resistivity (Ω · cm) 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
               
               
                 property 
                   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
               
               
                 Mechanical 
                 Tensile strength (MPa) 
                 91 
                 95 
                 67 
                 98 
                 84 
                 85 
                 151 
               
               
                 property 
                 Tensile strain (%) 
                 4.3 
                 4.1 
                 4.3 
                 4.7 
                 5.3 
                 5.4 
                 3.8 
               
               
                 Biodegradability 
                 Rate of change of 
                 32 
                 37 
                 36 
                 38 
                 38 
                 35 
                 32 
               
               
                   
                 posterior strength value 
               
               
                   
               
               
                   
                   
                   
                   
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
               
               
                   
                   
                 Specimen S8 
                 Specimen S9 
                 S10 
                 S11 
                 S12 
                 S13 
                 S14 
               
               
                   
               
               
                 Electrical 
                 Volume resistivity (Ω · cm) 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
               
               
                 property 
                   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
               
               
                 Mechanical 
                 Tensile strength (MPa) 
                 90 
                 71 
                 127 
                 145 
                 141 
                 80 
                 75 
               
               
                 property 
                 Tensile strain (%) 
                 4.7 
                 4.8 
                 4.3 
                 4.0 
                 4.2 
                 4.1 
                 4.5 
               
               
                 Biodegradability 
                 Rate of change of 
                 39 
                 39 
                 35 
                 32 
                 30 
                 38 
                 33 
               
               
                   
                 posterior strength value 
               
               
                   
               
               
                   
                   
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
               
               
                   
                   
                 S15 
                 S16 
                 S17 
                 S18 
                 S19 
                 S20 
                 S21 
               
               
                   
               
               
                 Electrical 
                 Volume resistivity (Ω · cm) 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
               
               
                 property 
                   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
               
               
                 Mechanical 
                 Tensile strength (MPa) 
                 73 
                 88 
                 75 
                 68 
                 84 
                 81 
                 79 
               
               
                 property 
                 Tensile strain (%) 
                 4.8 
                 4.1 
                 4.0 
                 4.4 
                 5.0 
                 4.7 
                 4.1 
               
               
                 Biodegradability 
                 Rate of change of 
                 34 
                 37 
                 32 
                 41 
                 40 
                 29 
                 30 
               
               
                   
                 posterior strength value 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 8 
               
               
                   
               
             
             
               
                   
                   
                   
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
               
               
                   
                   
                 Specimen S22 
                 S23 
                 S24 
                 S25 
                 S26 
                 S27 
                 S28 
               
               
                   
               
               
                 Electrical 
                 Volume resistivity (Ω · cm) 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
               
               
                 property 
                   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
               
               
                 Mechanical 
                 Tensile strength (MPa) 
                 84 
                 83 
                 61 
                 62 
                 76 
                 64 
                 59 
               
               
                 property 
                 Tensile strain (%) 
                 4.5 
                 5.3 
                 5.2 
                 5.0 
                 4.2 
                 4.6 
                 4.9 
               
               
                 Biodegradability 
                 Rate of change of 
                 36 
                 34 
                 40 
                 35 
                 29 
                 45 
                 42 
               
               
                   
                 posterior strength value 
               
               
                   
               
               
                   
                   
                   
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
               
               
                   
                   
                 Specimen S29 
                 S30 
                 S31 
                 S32 
                 S33 
                 S34 
                 S35 
               
               
                   
               
               
                 Electrical 
                 Volume resistivity (Ω · cm) 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
               
               
                 property 
                   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
               
               
                 Mechanical 
                 Tensile strength (MPa) 
                 76 
                 71 
                 97 
                 87 
                 89 
                 98 
                 69 
               
               
                 property 
                 Tensile strain (%) 
                 4.5 
                 5.2 
                 3.7 
                 4.4 
                 4.3 
                 4.6 
                 4.2 
               
               
                 Biodegradability 
                 Rate of change of 
                 42 
                 29 
                 45 
                 27 
                 34 
                 39 
                 41 
               
               
                   
                 posterior strength value 
               
               
                   
               
               
                   
                   
                   
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
               
               
                   
                   
                 Specimen S36 
                 S37 
                 S38 
                 S39 
                 S40 
                 S41 
                 S42 
               
               
                   
               
               
                 Electrical 
                 Volume resistivity (Ω · cm) 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
               
               
                 property 
                   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
               
               
                 Mechanical 
                 Tensile strength (MPa) 
                 63 
                 73 
                 53 
                 60 
                 69 
                 75 
                 56 
               
               
                 property 
                 Tensile strain (%) 
                 5.0 
                 5.4 
                 4.4 
                 3.9 
                 4.9 
                 5.6 
                 4.4 
               
               
                 Biodegradability 
                 Rate of change of 
                 96 
                 32 
                 43 
                 36 
                 37 
                 30 
                 44 
               
               
                   
                 posterior strength value 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 9 
               
               
                   
               
             
             
               
                   
                   
                 Specimen T1 
                 Specimen T2 
                 Specimen T3 
                 Specimen T4 
                 Specimen T5 
                 Specimen T6 
                 Specimen T7 
               
               
                   
               
               
                 Electrical 
                 Volume resistivity (Ω· cm) 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
               
               
                 property 
                   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
               
               
                 Mechanical 
                 Tensile strength (MPa) 
                 87 
                 99 
                 68 
                 91 
                 84 
                 85 
                 153 
               
               
                 property 
                 Tensile strain (%) 
                 4.3 
                 3.9 
                 4.5 
                 5.4 
                 5.2 
                 5.6 
                 3.8 
               
               
                 Biodegradability 
                 Rate of change of 
                 39 
                 34 
                 40 
                 33 
                 38 
                 40 
                 37 
               
               
                   
                 posterior strength value 
               
               
                   
               
               
                   
                   
                   
                   
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
               
               
                   
                   
                 Specimen T8 
                 Specimen T9 
                 T10 
                 T11 
                 T12 
                 T13 
                 Specimen T14 
               
               
                   
               
               
                 Electrical 
                 Volume resistivity (Ω· cm) 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
               
               
                 property 
                   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
               
               
                 Mechanical 
                 Tensile strength (MPa) 
                 96 
                 76 
                 136 
                 156 
                 143 
                 71 
                 73 
               
               
                 property 
                 Tensile strain (%) 
                 4.4 
                 4.9 
                 4.3 
                 4.0 
                 3.7 
                 4.0 
                 4.4 
               
               
                 Biodegradability 
                 Rate of change of 
                 33 
                 48 
                 37 
                 38 
                 31 
                 35 
                 33 
               
               
                   
                 posterior strength value 
               
               
                   
               
               
                   
                   
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
               
               
                   
                   
                 T15 
                 T16 
                 T17 
                 T18 
                 T19 
                 T20 
                 Specimen T21 
               
               
                   
               
               
                 Electrical 
                 Volume resistivity (Ω· cm) 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
               
               
                 property 
                   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
               
               
                 Mechanical 
                 Tensile strength (MPa) 
                 74 
                 91 
                 69 
                 76 
                 86 
                 78 
                 83 
               
               
                 property 
                 Tensile strain (%) 
                 4.7 
                 4.1 
                 4.5 
                 4.4 
                 4.5 
                 4.1 
                 4.2 
               
               
                 Biodegradability 
                 Rate of change of 
                 35 
                 37 
                 41 
                 29 
                 37 
                 35 
                 29 
               
               
                   
                 posterior strength value 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 10 
               
               
                   
               
             
             
               
                   
                   
                   
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
               
               
                   
                   
                 Specimen T22 
                 T23 
                 T24 
                 T25 
                 T26 
                 T27 
                 T28 
               
               
                   
               
               
                 Electrical 
                 Volume resistivity (Ω · cm) 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
               
               
                 property 
                   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
               
               
                 Mechanical 
                 Tensile strength (MPa) 
                 85 
                 82 
                 61 
                 67 
                 75 
                 70 
                 60 
               
               
                 property 
                 Tensile strain (%) 
                 4.4 
                 4.9 
                 4.8 
                 5.4 
                 4.3 
                 4.7 
                 4.8 
               
               
                 Biodegradability 
                 Rate of change of 
                 42 
                 41 
                 34 
                 36 
                 35 
                 36 
                 39 
               
               
                   
                 posterior strength value 
               
               
                   
               
               
                   
                   
                   
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
               
               
                   
                   
                 Specimen T29 
                 T30 
                 T31 
                 T32 
                 T33 
                 T34 
                 T35 
               
               
                   
               
               
                 Electrical 
                 Volume resistivity (Ω · cm) 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
               
               
                 property 
                   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
               
               
                 Mechanical 
                 Tensile strength (MPa) 
                 66 
                 68 
                 92 
                 83 
                 84 
                 94 
                 66 
               
               
                 property 
                 Tensile strain (%) 
                 4.3 
                 4.9 
                 4.1 
                 3.9 
                 4.1 
                 4.7 
                 4.7 
               
               
                 Biodegradability 
                 Rate of change of 
                 33 
                 30 
                 42 
                 26 
                 30 
                 41 
                 43 
               
               
                   
                 posterior strength value 
               
               
                   
               
               
                   
                   
                   
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
               
               
                   
                   
                 Specimen T36 
                 T37 
                 T38 
                 T39 
                 T40 
                 T41 
                 T42 
               
               
                   
               
               
                 Electrical 
                 Volume resistivity (Ω · cm) 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
               
               
                 property 
                   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
               
               
                 Mechanical 
                 Tensile strength (MPa) 
                 68 
                 84 
                 55 
                 62 
                 68 
                 70 
                 51 
               
               
                 property 
                 Tensile strain (%) 
                 5.4 
                 5.4 
                 4.4 
                 4.1 
                 4.6 
                 5.2 
                 4.2 
               
               
                 Biodegradability 
                 Rate of change of 
                 69 
                 32 
                 37 
                 31 
                 33 
                 38 
                 37 
               
               
                   
                 posterior strength value 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 11 
               
               
                   
               
             
             
               
                   
                   
                 Specimen P1 
                 Specimen P2 
                 Specimen P3 
                 Specimen P4 
                 Specimen P5 
                 Specimen P6 
                 Specimen P7 
               
               
                   
               
               
                 Electrical 
                 Volume resistivity (Ω · cm) 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
               
               
                 property 
                   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
               
               
                 Mechanical 
                 Tensile strength (MPa) 
                 71 
                 72 
                 50 
                 70 
                 68 
                 67 
                 110 
               
               
                 property 
                 Tensile strain (%) 
                 3.4 
                 3.1 
                 3.6 
                 3.9 
                 3.9 
                 4.0 
                 3.0 
               
               
                 Biodegradability 
                 Rate of change of 
                 95 
                 88 
                 100 
                 107 
                 107 
                 109 
                 85 
               
               
                   
                 posterior strength value 
               
               
                   
               
               
                   
                   
                   
                   
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
               
               
                   
                   
                 Specimen P8 
                 Specimen P9 
                 P10 
                 P11 
                 P12 
                 P13 
                 Specimen P14 
               
               
                   
               
               
                 Electrical 
                 Volume resistivity (Ω · cm) 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
               
               
                 property 
                   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
               
               
                 Mechanical 
                 Tensile strength (MPa) 
                 75 
                 56 
                 100 
                 115 
                 105 
                 58 
                 60 
               
               
                 property 
                 Tensile strain (%) 
                 3.4 
                 3.9 
                 3.2 
                 3.0 
                 3.0 
                 3.2 
                 3.2 
               
               
                 Biodegradability 
                 Rate of change of 
                 95 
                 107 
                 88 
                 91 
                 86 
                 86 
                 89 
               
               
                   
                 posterior strength value 
               
               
                   
               
               
                   
                   
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
               
               
                   
                   
                 P15 
                 P16 
                 P17 
                 P18 
                 P19 
                 P20 
                 Specimen P21 
               
               
                   
               
               
                 Electrical 
                 Volume resistivity (Ω · cm) 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
               
               
                 property 
                   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
               
               
                 Mechanical 
                 Tensile strength (MPa) 
                 60 
                 68 
                 55 
                 55 
                 70 
                 65 
                 65 
               
               
                 property 
                 Tensile strain (%) 
                 3.5 
                 3.0 
                 3.3 
                 3.3 
                 3.6 
                 3.4 
                 3.4 
               
               
                 Biodegradability 
                 Rate of change of 
                 90 
                 85 
                 92 
                 94 
                 99 
                 94 
                 94 
               
               
                   
                 posterior strength value 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 12 
               
               
                   
               
             
             
               
                   
                   
                   
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
               
               
                   
                   
                 Specimen P22 
                 P23 
                 P24 
                 P25 
                 P26 
                 P27 
                 P28 
               
               
                   
               
               
                 Electrical 
                 Volume resistivity (Ω · cm) 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
               
               
                 property 
                   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
               
               
                 Mechanical 
                 Tensile strength (MPa) 
                 65 
                 68 
                 45 
                 48 
                 55 
                 50 
                 45 
               
               
                 property 
                 Tensile strain (%) 
                 3.3 
                 4.0 
                 3.8 
                 4.0 
                 3.1 
                 3.7 
                 3.5 
               
               
                 Biodegradability 
                 Rate of change of 
                 94 
                 108 
                 97 
                 96 
                 93 
                 104 
                 105 
               
               
                   
                 posterior strength value 
               
               
                   
               
               
                   
                   
                   
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
               
               
                   
                   
                 Specimen P29 
                 P30 
                 P31 
                 P32 
                 P33 
                 P34 
                 P35 
               
               
                   
               
               
                 Electrical 
                 Volume resistivity (Ω · cm) 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
               
               
                 property 
                   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
               
               
                 Mechanical 
                 Tensile strength (MPa) 
                 55 
                 53 
                 70 
                 65 
                 68 
                 70 
                 53 
               
               
                 property 
                 Tensile strain (%) 
                 3.3 
                 3.8 
                 3.1 
                 3.2 
                 3.1 
                 3.5 
                 3.4 
               
               
                 Biodegradability 
                 Rate of change of 
                 104 
                 91 
                 103 
                 86 
                 100 
                 101 
                 99 
               
               
                   
                 posterior strength value 
               
               
                   
               
               
                   
                   
                   
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
                 Specimen 
               
               
                   
                   
                 Specimen P36 
                 P37 
                 P38 
                 P39 
                 P40 
                 P41 
                 P42 
               
               
                   
               
               
                 Electrical 
                 Volume resistivity (Ω · cm) 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
                 Higher than 
               
               
                 property 
                   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
                 1 × 10 15   
               
               
                 Mechanical 
                 Tensile strength (MPa) 
                 50 
                 60 
                 42 
                 46 
                 54 
                 57 
                 40 
               
               
                 property 
                 Tensile strain (%) 
                 4.0 
                 4.0 
                 3.3 
                 3.0 
                 3.8 
                 4.0 
                 3.2 
               
               
                 Biodegradability 
                 Rate of change of 
                 97 
                 93 
                 102 
                 94 
                 87 
                 94 
                 97 
               
               
                   
                 posterior strength value 
               
               
                   
               
             
          
         
       
     
         [0037]    It is found from Tables 7 to 12 that the specimens S1 to S42 employing the epoxidized linseed oil and T1 to T42 employing the epoxidized soybean oil were sufficiently high in volume resistivity as well as the specimens P1 to P42 employing the bisphenol-A-type epoxy resin and were high in both tensile strength and tensile strain as compared respectively with the specimens P1 to P42 (or in comparison between the specimens using the same curing agent, for example, between the specimens S1 and P1). Additionally, it is found that the specimens S1 to S42 and T1 to T42 were largely lower than the specimens P1 to P42 in posterior strength value. 
         [0038]    The vegetable oils used in the specimens S1 to S42 and T1 to T42 are an ester of glycerin and a fatty acid having a sufficient molecular length and therefore able to more ease a stress occurring when the epoxidized vegetable oils are cured than a stress occurring when the bisphenol-A-type epoxy resin is cured, which is considered as the reason for good tensile strength and good tensile strain of the specimens S1 to S42 and T1 to T42. Further, the vegetable oil in itself is naturally originated material and therefore susceptible to (or biodegraded by) microorganisms and enzymes in soil as compared with the specimens P1 to P42, which is considered to be the reason for the lower posterior strength value of the specimens S1 to S42 than the specimens P1 to P42. 
         [0039]    Accordingly, it is found that a polymer product can be obtain excellent electrical and mechanical properties when the polymer product has such a polymer material composition as to be exemplified by the specimens S1 to S42 and T1 to T42. Concerning the disposal of the polymer product, it is found that deleterious substances and carbon dioxide are not generated in such a large quantity as conventional polymer products (e.g. a product formed of bisphenol-A-type resins) emitted, even if incinerated. Further, it is found that the polymer product is biodegraded with time when landfilled. 
         [0040]    As discussed above, the embodiment of the present invention provides electrical and mechanical properties equal to or superior to those of the polymer material formed of conventional bisphenol-A-type epoxy resins without reducing the workability (for example, with ensuring a sufficient pot life), and additionally allows a contribution to global environmental protection. 
         [0041]    Although the invention has been described in detail by reference to the above-described embodiments and examples, the invention is not limited to the embodiments and examples described above. Modifications and variations of the embodiments and examples described above will occur to those skilled in the art, in light of the above teachings. 
         [0042]    For example, the present invention applies a vegetable oil (more specifically, an epoxidized vegetable oil) to a polymer material composition, and limits the effects of the vegetable oil neither in kind of the curing agent nor in curing conditions. Moreover, curing agents applicable to the present invention are not limited to those used in the present examples; for example, a mixture of two or more kinds of curing agents, an adduct thereof, salts thereof (e.g. dimethylaminomethylphenol) or the like can be applied to the present invention in view of an improvement in work environment and of shortening of operation time. Further, curing accelerators may be applied in addition to the curing agents. 
         [0043]    Although the curing agent used in the present examples was in a stoichiometric amount for the purpose of comparing the specimens S1 to S42 and T1 to T42 respectively with P1 to P42, the added amount of the curing agent is variously changed as necessary and not limited to the values applied to the present examples. In general, it is known that the polymer material composition can obtain good electrical and mechanical properties when the added amount of the curing agent is adjusted to about 80 to 90% of the stoichiometric amount. 
         [0044]    Furthermore, the curing agent may be implicitly functionally used, for example, by being enclosed in a microcapsule or by being adsorbed on a molecular sieve.