Abstract:
A nylon resin multi-layer pipe, excellent in adhesivity to a nylon resin joint, includes at least (A) a layer containing a copolymerized nylon and (B) a layer containing a nylon resin other than the copolymerized nylon of the layer (A). The surface in contact with the joint is the layer (A) containing a copolymerized nylon. An adhesion method is provided for adhering a nylon resin joint to the aforementioned nylon resin multi-layer pipe using a solvent adhesive.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a continuation of U.S. application Ser. No. 10/338,397, filed Jan. 8, 2003, the disclosure of which is incorporated herein by reference. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The present invention relates to a nylon resin multi-layer pipe which exhibits a sufficient adhesion strength when adhered to nylon resin joints using a solvent adhesive and a method for adhering the nylon resin multi-layer pipe to the nylon resin joints.  
           [0003]    Solvent adhesives are used for adhering nylon resin moldings to each other. Solvents for use in these solvent adhesives are required to dissolve nylon to be adhered. As solvents for the solvent adhesives adapted for nylons, phenolic compounds such as phenol, cresol and chlorophenol or fluoroalcohols are currently used, but all of these are so poisonous or stimulous that they are not preferred from the standpoint of working environment.  
           [0004]    Thus, in order to reduce toxicity of the phenolic compounds, those compounds have been used which have a phenolic hydroxyl group and one or more alkyl groups. Of these, a combination of carvacrol (2-methyl-5-isopropylphenol) and thymol (5-methyl-2-isopropylphenol) has a comparatively low toxicity and can remain liquid down to a temperature as low as −20° C. depending upon composition ratio, thus being usable over a wide range of temperature. A solvent adhesive obtained by dissolving nylon in this mixed solvent of carvacrol and thymol is used for adhering a nylon gas pipe to a nylon joint.  
           [0005]    However, in cases where an enough peel strength is required at adhesion portions between the pipe and the joint or in other uses, the current adhesion strength is not enough, and use of the adhesives has been limited.  
         BRIEF SUMMARY OF THE INVENTION  
         [0006]    An object of the invention is to provide a nylon resin pipe which can provide an enough peel strength when adhered to nylon resin joints using a solvent adhesive.  
           [0007]    Mechanism of adhesion using a solvent adhesive is that, first, materials to be adhered are dissolved in the solvent adhesive at the adhesion portion, and the dissolved polymer molecule chains then mutually invade into the materials to be adhered, and the solvent evaporates or is absorbed by the materials to be adhered to form a dry, solidified adhesion layer at the adhesion interface. Therefore, solvents for the solvent adhesive are essentially required to sufficiently dissolve materials to be adhered.  
           [0008]    The invention is based on the finding that, by the use of a nylon resin multi-layer pipe comprising a layer containing a copolymerized nylon as a surface to be adhered to nylon resin joint, an adhesion layer can be more effectively formed at the adhesion interface, making it possible to improve the adhesion strength.  
           [0009]    That is, the invention relates to the following Embodiments (1) to (10):  
           [0010]    (1) A nylon resin multi-layer pipe excellent in adhesivity to a nylon resin joint comprising at least (A) a layer containing a copolymerized nylon and (B) a layer containing a nylon resin other than the copolymerized nylon of the layer (A) wherein the surface in contact with the joint is the layer (A) containing a copolymerized nylon.  
           [0011]    (2) The nylon resin multi-layer pipe as described in (1), wherein the copolymerized nylon comprises two or more units derived from a C 6 -C 12  lactam, a C 6 -C 12  aminocarboxylic acid, and a combination of a C 3 -C 22  dicarboxylic acid and a C 2 -C 20  diamine.  
           [0012]    (3) The nylon resin multi-layer pipe as described in (1), wherein the layer (B) is a layer containing nylon 11 or nylon 12.  
           [0013]    (4) The nylon resin multi-layer pipe as described in (1), wherein the outer layer is a layer containing a copolymerized nylon and the inner layer is a layer containing nylon 11 or nylon 12.  
           [0014]    (5) The nylon resin multi-layer pipe as described in (1), wherein the inner layer is a layer containing a copolymerized nylon and the outer layer is a layer containing nylon 11 or nylon 12.  
           [0015]    (6) The nylon resin multi-layer pipe as described in (1), wherein the outer layer and the inner layer are layers containing a copolymerized nylon and the interlayer is a layer containing nylon 11 or nylon 12.  
           [0016]    (7) The nylon resin multi-layer pipe as described in any one of (1) to (6), wherein the copolymerized nylon contains a nylon 12 component in an amount of from 5 to 95% by weight based on the weight of the copolymerized nylon.  
           [0017]    (8) An adhesion method which comprises adhering a nylon resin joint to a nylon resin multi-layer pipe as described in any one of (1) to (7) using a solvent adhesive.  
           [0018]    (9) The adhesion method as described in (8), wherein the solvent adhesive contains at least one of phenolic compounds and fluoroalcoholic compounds.  
           [0019]    (10) The adhesion method as described in (8) or (9), wherein the solvent adhesive contains a copolymerized nylon.  
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0020]    The foregoing summary, as well as the following detailed description of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. In the drawings:  
         [0021]    [0021]FIG. 1 is a sectional view illustrating the case where a pipe is adhered using a female joint;  
         [0022]    [0022]FIG. 2 is a sectional view illustrating the case where a pipe is adhered using a male joint; and  
         [0023]    [0023]FIG. 3 is a sectional view illustrating the case where adhesion is made using a female joint and a male joint in combination. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0024]    The invention will be further described hereinafter.  
         [0025]    The copolymerized nylon to be used in the pipe of the invention is a copolymerized nylon comprising two kinds or more units derived from aminocarboxylic acids, lactams or a combination of diamine and dicarboxylic acid. Specifically, there are illustrated those which comprise two or more units derived from lactams containing 6 to 12 carbon atoms, aminocarboxylic acids containing 6 to 12 carbon atoms or a combination of a dicarboxylic acid containing 3 to 22 carbon atoms and a diamine containing 2 to 20 carbon atoms.  
         [0026]    As the aminocarboxylic acid containing 6 to 12 carbon atoms, there may be used 6-aminocaproic acid, 7-aminoheptanoic acid, 8-aminooctanoic acid, 9-aminononanoic acid, 10-aminocapric acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, etc.  
         [0027]    As the lactam containing 6 to 12 carbon atoms, there may be used ε-caprolactam, ω-enantolactam, ω-undecanelactam, ω-dodecalactam, etc.  
         [0028]    As the diamine and dicarboxylic acid, linear diamines and linear dicarboxylic acids are used but, for the purpose of decreasing crystallinity, there may be used copolymerized nylons wherein part of starting materials of nylons derived from the linear diamine and the linear dicarboxylic acid may be replaced by a branched diamine and/or a branched dicarboxylic acid.  
         [0029]    As the linear aliphatic dicarboxylic acid, there may be used malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecane dicarboxylic acid, dodecane dicarboxylic acid, tridecane dicarboxylic acid, tetradecane dicarboxylic acid, pentadecane dicarboxylic acid, hexadecane dicarboxylic acid, heptadecane dicarboxylic acid, octadecane dicarboxylic acid, nonadecane dicarboxylic acid, eicosane dicarboxylic acid, etc.  
         [0030]    As the linear aliphatic diamine, there may be used ethylenediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, 1,13-tridecanediamine, 1,14-tetradecanediamine, 1,15-pentadecanediamine, 1,16-hexadecanediamine, 1,17-heptadecanediamine, 1,18-octadecanediamine, 1,19-nonadecanediamine, 1,20-eicosanediamine, etc.  
         [0031]    As the branched aliphatic diamine, there may be used 1-butyl-1,2-ethanediamine, 1,1-dimethyl-1,4-butanediamine, 1-ethyl-1,4-butanediamine, 1,2-dimethyl-1,4-butanediamine, 1,3-dimethyl-1,4-butanediamine, 1,4-dimethyl-1,4-butane-diamine, 2,3-dimethyl-1,4-butanediamine, 2-methyl-1,5-pentanediamine, 3-methyl-1,5-pentanediamine, 2,2-dimethyl-1,6-hexanediamine, 2,5-dimethyl-1,6-hexanediamine, 2,4-dimethyl-1,6-hexanediamine, 3,3-dimethyl-1,6-hexane-diamine, 2,2,4-trimethyl-1,6-hexanediamine, 2,4,4-trimethyl-1,6-hexanediamine, 2,4-diethyl-1,6-hexanediamine, 2,2-dimethyl-1,7-heptanediamine, 2,3-dimethyl-1,7-heptanediamine, 2,4-dimethyl-1,7-heptanediamine, 2,5-dimethyl-1,7-peptanediamine, 2-methyl-1,8-octanediamine, 3-methyl-1,8-octanediamine, 4-methyl-1,8-octanediamine, 1,3-dimethyl-1,8-octanediamine, 1,4-dimethyl-1,8-octane-diamine, 2,4-dimethyl-1,8-octanediamine, 3,4-dimethyl-1,8-octanediamine, 4,5-dimethyl-1,8-octanediamine, 2,2-dimethyl-1,8-octanediamine, 3,3-dimethyl-1,8-octane-diamine, 4,4-dimethyl-1,8-octanediamine, 5-methyl-1,9-nonanediamine, etc.  
         [0032]    As the branched aliphatic dicarboxylic acid, there may be used dimethylmalonic acid, 3,3-diethylsuccinic acid, 2,2-dimethylglutaric acid, 2-methyladipic acid, 3-methyladipic acid, trimethyladipic acid, 2-butylsuberic acid (also named 1,6-decane dicarboxylic acid), 2,3-dibutylbutane dioic acid, 8-ethyloctadecane dioic acid, 8,13-dimethyleicosadioic acid, 2-octylundecane dioic acid, 2-nonyldecane dioic acid, etc.  
         [0033]    As the copolymerized nylon to be used in the invention as a material for the multi-layer pipe, there may be used a binary copolymerized nylon comprising two components derived from the above-described starting materials or a copolymerized nylon comprising three or more components derived from the above-described starting materials.  
         [0034]    As the nylon to be used as the layer (A) of the multi-layer pipe of the invention, the copolymerized nylon may independently be used, or may be used as a blend of the copolymerized nylon and a homonylon or a blend of the copolymerized nylon and other copolymerized nylon. As the copolymerized nylon blend, there are illustrated, for example, a blend of the copolymerized nylon and a nylon selected from the group consisting of nylon 6, nylon 11, nylon 12, nylon 6,6, nylon 6,10 and nylon 6,12. The term “nylon 6,6” as used herein means a homonylon obtained by polymerizing a diamine containing 6 carbon atoms with a dicarboxylic acid containing 6 carbon atoms.  
         [0035]    As specific examples of the nylon resins to be used as the layer (B) of the multi-layer pipe of the invention, there are illustrated aliphatic polyamides such as nylon 6, nylon 6,6, nylon 11 and nylon 12 and semi-aromatic polyamide resins such as polyhexamethylene terephthalamide and polyhexamethylene isophthalamide. These resins may comprise a single copolymer or a mixture of two or more copolymers.  
         [0036]    The copolymerized nylon and other nylon resins to be used in the multi-layer pipe of the invention may be used comprising additives such as heat-resistant material, weathering-resistant material, oxidation inhibitor, ultraviolet absorber, fire retardant, impact resistance-imparting agent, antistatic agent, plasticizer, nucleating agent and lubricant incorporated therein as necessary.  
         [0037]    Further, the copolymerized nylon and other nylon resins to be used in the multi-layer pipe of the invention may be used comprising reinforcements such as glass fiber, inorganic fiber, organic fiber and carbon black incorporated therein as necessary.  
         [0038]    Moreover, the copolymerized nylon and other nylon resins to be used in the multi-layer pipe of the invention may be used comprising coloring materials such as pigment and dye incorporated therein as necessary.  
         [0039]    As specific examples of the material of the nylon resin joint to be adhered to the multi-layer pipe of the invention, there are illustrated aliphatic polyamides such as nylon 6, nylon 6,6, nylon 11 and nylon 12 and semi-aromatic polyamide resins such as polyhexamethylene terephthalamide and polyhexamethylene isophthalamide. These resins may comprise a single polymer or a mixture of two or more copolymers.  
         [0040]    In the invention, the nylon resin joint and the aforementioned nylon resin multi-layer pipe are adhered to each other using a solvent adhesive.  
         [0041]    As the solvent adhesive to be used in the adhesion of the multi-layer pipe of the invention to nylon resin joint, those adhesives may be used which comprise a solvent capable of dissolving nylon resins to be used in pipes or joints, such as a phenolic compound (e.g., phenol, alkylphenol, etc.) and a fluoroalcoholic compound.  
         [0042]    As the phenolic compounds, there are illustrated phenol, o-cresol, m-cresol, p-cresol, o-ethylphenol, m-ethylphenol, p-ethylphenol, o-propylphenol, m-propyl-phenol, o-isopropylphenol, m-isopropylphenol, p-isopropylphenol, o-n-butylphenol, m-n-butylphenol, p-n-butylphenol, o-sec-butylphenol, m-sec-butylphenol, p-sec-butylphenol, o-tert-butylphenol, m-tert-butylphenol, p-tert-butylphenol, 4-amylphenol, 4-octylphenol, 4-tert-octylphenol, 4-nonylphenol, 4-dodecylphenol, 2,3-di methyl phenol, 2,4-di methyl phenol, 2,5-di methylphenol, 2,6-dimethylphenol, 3,4-dimethylphenol, 3,5-dimethyl-phenol, 4-isopropyl-3-methylphenol, 5-isopropyl-2-methylphenol (also called carvacrol), 6-isopropyl-3-methylphenol (also called thymol), 2-tert-butyl-4-methylphenol, 6-tert-butyl-3-methylphenol, 6-tert-butyl-2-methylphenol, 6-tert-butyl-2,4-dimethylphenol, 4,6-tert-butyl-3-methylphenol, resorcinol, 2-methylresorcinol, 4-methylresorcinol, 5-methylresorcinol, 2-ethylresorcinol, 4-ethylresorcinol, 5-ethylresorcinol, 2-butylresorcinol, 4-butylresorcinol, 5-butylresorcinol, 2-amylresorcinol, 4-amylresorcinol, 5-amylresorcinol, 2-hexylresorcinol, 4-hexylresorcinol, 5-hexylresorcinol, 2-heptylresorcinol, 4-heptylresorcinol, 5-heptylresorcinol, 2-octylresorcinol, 4-octylresorcinol, 5-octylresorcinol, 2-nonylresorcinol, 4-nonylresorcinol, 5-nonylresorcinol, 2-dodecylresorcinol, 4-dodecylresorcinol, 5-dodecylresorcinol, catechol, 3-methylcatechol, 4-methylcatechol, hydroquinone, 1,2,3-trihydroxybenzene (also called pyrogallol) and 1,3,5-trihydroxybenzene (also called phloroglucinol).  
         [0043]    As the fluoroalcoholic compounds, there are illustrated 1,1,1,3,3,3-hexafluoroisopropanol, and 1,1,1-trifluoroethanol.  
         [0044]    Of these, a combination of carvacrol (2-methyl-5-isopropylphenol) and thymol (5-methyl-2-isopropylphenol) is preferred, because it shows a comparatively low toxicity and can remain liquid to below −20° C. depending upon the composition ratio, thus permitting to use over a wide range of temperature.  
         [0045]    In the invention, a solvent adhesive containing a nylon resin, in particular, a copolymerized nylon is preferred as the solvent adhesive. Incorporation of the copolymerized nylon enables formation of an adhesive layer at the adhesion interface with more effectivity, thus adhesion strength being improved.  
         [0046]    As the copolymerized nylon, there may be used those copolymerized nylons which comprise two kinds or more units derived from a lactam containing 6 to 12 carbon atoms, an aminocarboxylic acid containing 6 to 12 carbon atoms, or a combination of a dicarboxylic acid containing 3 to 22 carbon atoms and a diamine containing 2 to 20 carbon atoms.  
         [0047]    Concentration of the copolymerized nylon contained in the adhesive is preferably 0.5 to 20% by weight based on the total weight of the adhesive. In case where concentration of the copolymerized nylon is less than 0.5% by weight, viscosity of the resulting adhesive becomes too low that it tends to run upon application, thus being difficult to handle. On the other hand, in case where concentration of the copolymerized nylon becomes more than 20% by weight, viscosity becomes so high that it becomes difficult to handle and that it takes long before solidification.  
         [0048]    In the multi-layer pipe of the invention, as shown in FIG. 1, in the case where a female joint  1  and a pipe are adhered to each other using a solvent adhesive, the use of a nylon resin multi-layer pipe comprising an outer layer  2  in contact with the joint made of a copolymerized nylon and an inner layer  3  made of other nylon resins makes it possible to realize an excellent peel strength. As shown in FIG. 2, in the case where a male joint  4  and a pipe are adhered to each other using a solvent adhesive, the use of a nylon resin multi-layer pipe comprising an inner layer  5  in contact with the joint made of a copolymerized nylon and an outer layer  6  made of other nylon resins makes it possible to realize an excellent peel strength. As shown in FIG. 3, in the case where a female joint  7  and a male joint  8  are adhered in combination to a pipe using a solvent adhesive, the use of a nylon resin multi-layer pipe comprising an inner layer  9  and an outer layer  10  which are each in contact with the joint and made of a copolymerized nylon and an interlayer  11  made of other nylon resins makes it possible to realize an excellent peel strength.  
         [0049]    The invention will be explained below in more detail by reference to the following Examples and Comparative Examples, but the invention should not be construed as being limited thereto.  
         [0050]    Tensile test specimens (Type 1) were prepared according to ASTM D638 using nylon 12 or copolymerized nylon, which were referred to as materials A to be adhered. Then, pressed sheets prepared by compression molding were cut into 12.7 mm×120 mm×0.6 mmt test specimens, which were referred to as materials B to be adhered. Among these materials B, two-layer formed sheets were prepared in such a manner that they have a total thickness of 0.6 mm and comprise a nylon layer 12 having a thickness of 0.5 mm and a copolymerized nylon layer having a thickness of 0.1 mm. The material A to be adhered and the material B to be adhered were adhered to each other using a solvent adhesive. The margin for adhesion was 50 mm. The laminate thus formed was cured for 6 days, and then subjected to peeling test. The distance between grips was 40 mm, and the rate of pulling was 200 mm/min.  
       EXAMPLE 1  
       [0051]    The material A to be adhered was prepared from nylon 12. The material B to be adhered was prepared as a two-layer formed sheet comprising nylon 12 and copolymerized nylon A (nylon 6/nylon 12=40/60). The material A to be adhered and the material B to be adhered were adhered to each other using an adhesive A (10% by weight solution of nylon 11 in carvacrol/thymol=2/1), and then subjected to peeling test.  
       EXAMPLE 2  
       [0052]    The material A to be adhered was prepared from copolymerized nylon A (nylon 6/nylon 12=40/60). The material B to be adhered was prepared as a two-layer formed sheet comprising nylon 12 and copolymerized nylon A (nylon 6/nylon 12=40/60). The material A to be adhered and the material B to be adhered were adhered to each other using an adhesive A (10% by weight solution of nylon 11 in carvacrol/thymol=2/1), and then subjected to peeling test.  
       EXAMPLE 3  
       [0053]    The material A to be adhered was prepared from copolymerized nylon B (nylon 6/nylon 12=25/75). The material B to be adhered was prepared as a two-layer formed sheet comprising 10 nylon 12 and copolymerized nylon A (nylon 6/nylon 12=40/60). The material A to be adhered and the material B to be adhered were adhered to each other using an adhesive A (10% by weight solution of nylon 11 in carvacrol/thymol=2/1), and then subjected to peeling test.  
       EXAMPLE 4  
       [0054]    The material A to be adhered was prepared from copolymerized nylon A (nylon 6/nylon 12=40/60). The material B to be adhered was prepared as a two-layer formed sheet comprising nylon 12 and copolymerized nylon A (nylon 6/nylon 12=40/60). The material A to be adhered and the material B to be adhered were adhered to each other using an adhesive B (5% by weight solution of copolymerized nylon A in methanol/resorcinol=6/4), and then subjected to peeling test.  
       COMPARATIVE EXAMPLE 1  
       [0055]    Both the materials A and B to be adhered were prepared from nylon 12. The material A to be adhered and the material B to be adhered were then adhered to each other using an adhesive A (10% by weight solution of nylon 11 in carvacrol/thymol=2/1), and then subjected to peeling test.  
       COMPARATIVE EXAMPLE 2  
       [0056]    The material A to be adhered was prepared from nylon 12 and the material B to be adhered was prepared from copolymerized nylon A (nylon 6/nylon 12=40/60). The material A to be adhered and the material B to be adhered were then adhered to each other using an adhesive A (10% by weight solution of nylon 11 in carvacrol/thymol=2/1), and then subjected to peeling test.  
       COMPARATIVE EXAMPLE 3  
       [0057]    The material A to be adhered was prepared from nylon 12 and the material B to be adhered was prepared from copolymerized nylon B (nylon 6/nylon 12=25/75). The material A to be adhered and the material B to be adhered were then adhered to each other using an adhesive A (10% by weight solution of nylon 11 in carvacrol/thymol=2/1), and then subjected to peeling test.  
       COMPARATIVE EXAMPLE 4  
       [0058]    The material A to be adhered was prepared from nylon 12 and the material B to be adhered was prepared from copolymerized nylon C (nylon 6/nylon 12=80/20). The material A to be adhered and the material B to be adhered were then adhered to each other using an adhesive A (10% by weight solution of nylon 11 in carvacrol/thymol=2/1), and then subjected to peeling test.  
                                                         TABLE 1                                   Material A   Material B                   to be   to be       Peel           adhered   adhered   Adhesive   strength (N)                                    Example 1   Nylon 12   Two-layer   Adhesive A   171.3               formed               product-1       Example 2   Copolymer-   Two-layer   Adhesive A   160.3           ized nylon A   formed               product-1       Example 3   Copolymer-   Two-layer   Adhesive A   165.8           ized nylon B   formed               product-1       Example 4   Copolymer-   Two-layer           ized nylon A   formed   Adhesive B   192.9               product-1       Comparative   Nylon 12   Nylon 12   Adhesive A   9.0       Example 1       Comparative   Nylon 12   Copolymer-   Adhesive A   105.1       Example 2       ized nylon A       Comparative   Nylon 12   Copolymer-   Adhesive A   106.1       Example 3       ized nylon B       Comparative   Nylon 12   Copolymer-   Adhesive A   86.5       Example 4       ized nylon C                  
 
         [0059]    In Examples 2 and 3, the material B underwent break.  
         [0060]    The use of the nylon resin multi-layer pipe of the invention makes it possible to form an adhesion layer effective in the adhesion with a solvent adhesive and thus allows use in purposes requiring a strong peel strength.  
         [0061]    While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.