Abstract:
A polyarylenesulfide resin composition manufactured by compounding polyarylenesulfide resin with one or more ester-based compounds selected from the groups of compounds shown in the following formulas (1) and (2): ##STR1## where R 1  to R 4  are such that at least one of them is an alkyl or alkenyl group of 10-40 carbon atoms, the remaining Rs represent --H, --OH, alkyl, or aryl radicals, and 1.0&lt;m&lt;6.0 ##STR2##

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a polyarylene sulfide (hereinafter &#34;PAS&#34;) resin composition that is excellent in moldability and in mechanical properties. More specifically the present invention relates to a PAS resin composition characterized in that the separability of a molding from the metal mold (hereafter referred to as &#34;mold separability&#34;) can be drastically improved independently of the mold temperature at the time of injection molding, thereby shortening the molding time and increasing mechanical strength of the molding to provide a wider range of applicable fields. This is accomplished by combining a specified ester-based compound, as a mold separating agent, into PAS resin. 
     2. Background of the Invention 
     In recent years, high heat-resistant thermoplastic resin has been in demand as a component material of instruments for electrical, electronic, automobile, and chemical applications. PAS resin may satisfy this need. However, PAS resin occasionally suffers a drawback in that stable and continuous molding becomes difficult, resulting in a slow molding speed (molding cycle) and poor productivity. This problem arises because PAS resin has good affinity with metals and shrinks slightly in the process of solidification from a molten state. On the other hand, many moldings require the use of precise and complicated metal molds, leading to poor mold separability. 
     In order to overcome these defects related to mold separability, some countermeasures have been taken in which the cavity of a metal mold is sprayed with silicone oil, or PAS resin is added with zinc stearate (Published Unexamined Japan Patent Application No. 54-162752) or fatty acid amide such as N,N&#39;-alkylene bisalkane amide (U.S. Pat. No. 4,395,509). 
     For this purpose, however, silicone oil, when sprayed into the cavity, exhibits remarkable mold separability but must be sprayed once or more for every few shots. In the case of moldings having a weld part, the oil concentrates on the weld part and deteriorates weld strength, duplicating the problem with PAS resin. In addition, electrical contacts may malfunction because silicone oil attaches to moldings when the moldings are used for electric or electronic parts. Adding zinc stearate or fatty acid amide (such as N,N&#39;-alkylene bisalkane amide) to some degree aids mold separation, but discoloration, lowering of the mechanical strength in moldings, and gas generation due to the low thermal decomposition temperature of the added compounds also result in kneading and molding processes. Generated gas also lowers resin strength at weld parts in moldings. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to provide a PAS resin composition that is improved in mold separability and resistant to thermal decomposition, releases only small amounts of gas during the molding process, and has excellent mechanical properties. 
     Through numerous tests and studies, the inventors have developed this invention by finding that the addition of a compound based on a specific kind of ester to PAS resin can provide a very stable PAS-resin based composition that does not decompose even at the molding temperature of the PAS resin but shows little evolution of gases, no lowering of mechanical properties, a mold separating effect over a very wide range of metal mold temperatures--60° to 160° C.--and, further, superior adhesiveness to other kinds of materials. More specifically, the invention relates to a PAS resin composition that is composed of one or more ester-based compounds selected from the group of compounds shown in the following formulas (1) and (2). ##STR3## where R 1  to R 4  are such that at least one of them is an alkyl or alkenyl group of 10-40 carbon atoms and the remaining R&#39;s represent --H, --OH, alkyl- or aryl radicals; 1.0&lt;m&lt;6.0 ##STR4## 
     The PAS resin of this invention includes preferably more than 90 mol % of the structural unit shown below ##STR5## Otherwise, it is difficult to provide a PAS composition having excellent characteristics. Polyphenylene sulfide (PPS) is preferable. 
     In order to obtain this compound by polymerization, various methods may be enumerated, such a (1) polymerization of p-dichlorobenzene in the presence of sulfur and sodium carbonate or in the presence of sodium hydroxide and sodium sulfide/sodium hydrogen sulfide in a polar solvent; and self-condensation of p-chlorothiophenol. However, the most suitable method is to react sodium sulfide with p-dichlorobenzene in an amide-based solvent such as N-methylpyrrolidone, dimethylacetoamide, or a sulfone-based solvent such as sulfolane. The degree of polymerization is adjusted preferably by adding alkarine metal salts of carboxylic acid/sulfonic acid or adding alkari hydroxide. Copolymer ingredients occupying less than 50 mol %, preferably less than 40 mol % of the whole resin can include a ##STR6## where R represents alkyl-, nitro-, phenyl-, carboxyl radicals, metallic salt radical of carboxylic acid, alkoxy- or amino radicals. In addition, the resin can include preferably less than 5 mol %, preferably 3 mol % of three-functional bonds such as; ##STR7## 
     Such PAS resin can be synthesized by general manufacturing methods such as (1): the reaction between a halogen-substituted aromatic compound and alkari sulfide (refer to U.S. Pat. No. 2,513,188, Published Unexamined Japan Patent Application No. 44-27671 and No. 45-3368); (2): the condensation reaction of thiophenols in the presence of alkari catalyst or copper salts (refer to U.S. Pat. No. 3,274,165, UK Patent No. 1160660); (3): the condensation reaction of an aromatic compound in the co-presence of sulfur chloride and Lewis acid catalyst (refer to Published Unexamined Japan Patent Application No. 46-27255, Belgium Patent No. 29437). Any such method may be selected according to the conditions and requirements. 
     While any ester-based compound having the structure shown in the preceding formulas (1) or (2) can be effectively used as an ingredient of the composition according to the present invention, that indicated in Formula (1) is preferable. 
     This compound may preferably be exemplified by fatty acid ester of polyhydric alcohol such that all of R 1  to R 4  in formula (1) are alkyl radicals and/or alkenyl radicals of 10-40 carbon atoms, preferably alkyl radicals of 15-35 carbon atoms. In Formula (1) m should preferably be 2.0-4.0. 
     The typical substance indicated in Formula (1) covers fatty acid ester of neopentyl polyol (e.g., higher fatty ester of neopentyl alcohol, neopentyl glycol, or pentaerythritol). Particularly preferable are stearic acid ester or montanic acid ester of dimer to quadrimer or their mixture of pentaerithritol. 
     Out of the compounds shown by Formula (2), phthalic acid ester where the number of carbon atoms of R 5  is more than 25, particularly 40-60, is preferable. If the number of carbon atoms of R 5  is less than 25, the mechanical strength of PAS resin is markedly reduced. The ester-based compounds related to this invention as shown in the above-stated formulas (1) and (2) are preferably use in the amounts of 0.01 to 6 wt. pts. of PAS resin to completely achieve the purpose of the invention, achieving good mechanical properties in the composition. 
     To the composition of this invention can be added reinforcing fibers, preferably glass fibers and carbon fibers and/or other inorganic fillers. The glass fiber to be used is preferably such that element wires made of alkali-free glass fibers having a diameter of 5-20 and μm and are surface-treated with a silane coupling agent and an organic material called binder for bundling and cut in lengths of 3-6 mm. While the carbon fibers may be based on either of polyacrylonitrile or pitch, their element wires preferably have a diameter of 5-20 and μm and are surface-treated with epoxy-based resin nylon-based resin, or are left untreated. 
     Other inorganic fillers that can be used in the composition include calcium carbonate, talc, kaolin, clay, mica, wollastonite, calcium sulfate, silica, glass beads, milled glass fibers, milled carbon fibers, titanium oxide, graphite, and processed mineral fibers. 
     The quantitative proportion of these reinforcing fibers and other inorganic fillers is preferably 20-70 wt. % of the whole resin composition. In this case, the reinforcing fibrous material and other inorganic fillers can be used singly or jointly. 
     The composition related to this invention can have added, to any extent not hampering the aims of the invention, one or more thermoplastic resins--for example, polyphenylene ether, polyacetal, polyarylate, teflon resin, polyamide, polycarbonate, polysulfone, polyethersulfone, polyetherketone, polybutylene terephthalate, polyethylene terephathalate, polyamide imide, polyetherimide, polyethylene, polypropylene, and epoxyresin. 
     Fatty acid esters may be added to PAS resin in this invention using publicly known methods, wherein, for example, powdery or pelleted PAS resin and powdery, flakey, granular, or pelleted fatty acid ester, if required, together with a reinforcing agent such as glass-fiber and/or other inorganic fillers such as calcium carbonate, are preliminarily mixed mechanically and uniformly in a mixer such as drum tumbler and subjected to heating, melting and kneading processes in a screw type single/dual axis kneading/excluding machine; this is followed by cooling and pelletting. 
     To the composition of the present invention may be added small amounts of coloring material, heat-resistant stabilizer, UV stabilizer, rust preventives, crystal nucleating agents, and organic silane compounds as reforming agents to any extent that fulfills the purpose of the present invention. 
     The composition of this invention is used for various molding materials such as those for instrument parts in electrical, electronic, automobile, and chemical applications. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The invention is explained in detail with reference to the following embodiments, though the invention is not limited in extent by these embodiments. It should be noted that parts are represented by weight. 
     Embodiment 1-6 
     Powdery PPS resin merchandised from Phillips Petroleum Inc. U.S.A. under the trade name of RYTON &#34;p-4&#34; is mixed with various additive compounds at the ratios shown in Table 1 to obtain a total weight 6 kg. The mixture is then put into 30-liter tumbler and is uniformly mixed at a speed of 80 rpm for about one minute. Sixty weight-percent of the above mixture fed at a rate of 15 kg/h and 40 wt. % chopped glass fiber (trade name: glassron chopped strand &#34;CS-03-MA-497&#34; made by Asahi fiber glass Co., Ltd.) fed at a rate of 10 kg/h are fed separately into a high-speed unidirectional biaxial kneading and extruding machine (Toshiba Machining Corporation, Ltd. TEM-35B) having a screw diameter of 37 mm, L/D=32, and a bend in order to be kneaded in the conditions that the cylinder temperature is 320° C., screw rotation is 250 rpm, and the discharge rate is 25 kg/h. Next, the mixture is discharged through a nozzle with a bore diameter of 3.6 mm, air-cooled, and finally cut into pellets 3 mm long by means of a strand cutter. 
     Molding was performed using a metal mold having a cylindrical cavity whose external diameter, internal diameter, and length are 30 mm, 28 mm, and 10 mm, respectively and whose LVS is one degree. The mold is mounted on a Sumitomo-Nestal injection molding machine, Model SAYCAP S165/75, with a maximum clamping force of 75 tons, and manufactured by Sumitomo Heavy Industries Ltd. The metallic mold temperature is 150° C.; the cylinder temperature of the molding machine is 320° C.; the injection speed is 30 mm/s; the primary injection pressure is 35 kgf/cm 2  ; the secondary injection pressure is 28 kgf/cm 2  ; the injection-pressurizing time is 3s (primary) and 3s (secondary); and the cooling time is 15 s. The amount of gas generated under these conditions was visually determined. The mold separating force working on the protruding pin was measured in the process in which the mold is opened and protruded after the cooling process finished using a pressure sensor (#9221, manufactured by KISTLER Ltd, Switzerland) mounted on one of three protruding pins each having a diameter of 1 mm. The mechanical strength was obtained by measuring the bending characteristic in compliance with ASTMD 790. The results are shown in Table 1. At this time of injection molding, the amount of gas generated was less than that in the following embodiments 7-12 and 13-18. 
     Embodiment 7-12 
     Various additives were compounded with PPS resin to prepare the corresponding compositions in a pellet form as in Embodiments 1-6. These samples were subjected to tests similar to those in Embodiments 1-6. The results are shown in Table 2. 
     Embodiments 13-18 
     Various additives were compounded with PPS resin to prepare the corresponding compositions in a pellet form as in Embodiments 1-6. These samples were subjected to tests similar to those in Embodiments 1-6. The results are shown in Table 3. 
     EXAMPLE FOR COMPARISON 1-6 
     Various additives were compounded with PPS resin to prepare the corresponding compositions in a pellet form as in Embodiments 1-6. These samples were subjected to tests similar to those in Embodiments 1-6. The results are shown in Table 4. 
     
                                           TABLE 1__________________________________________________________________________                           Dependence of model   Additive    Bending characteristics                           resistor on metal mold                                           Gas generated        Addition wt.               Strength                    Fracture                           temperature kgf/cm.sup.2                                           during injection   Species        %      kgf/cm.sup.2                    elongation %                           60° C.                               90° C.                                   120° C.                                       150° C.                                           molding__________________________________________________________________________Embodiment 1   DPET-M        0.3    2450 2.15   15  10  5   3   LittleEmbodiment 2   PPET-M        0.3    2450 2.16   15   9  3   3   LittleEmbodiment 3   DPET-S        0.3    2430 2.10   20  13  5   5   LittleEmbodiment 4   DPET-S        1.0    2430 2.12   15  10  5   3   LittleEmbodiment 5   PPET-S        0.3    2450 2.15   18  10  4   3   LittleEmbodiment 6   PPET-S        1.0    2440 2.14   12   8  4   3   Little__________________________________________________________________________Composition of ingredients in mixtureName of compound (additive)          %PPS; RYTON P-4 60-XGF; CS-03-MA-497          40Additive       XDPET-M: Abbreviation for dipentaerythritol hexamontanate m = 2.0PPET-M: Abbreviation for polypentaerythritol montante m = 3.4(Esterification factor of montanic acid: 70%)DPET-S: Abbreviation for dipentaerythritol hexastearate m = 2.0PPET-S: Abbreviation for polypentaerythritol stearate m = 3.4(Esterification factor of stearic acid: 70%) 
    
     
                                           TABLE 2__________________________________________________________________________                                Dependence of model   Additive         Bending characteristics                                resistor on metal mold                                                  Gas generated             Addition wt.                    Strength                         Fracture                                temperature kgf/cm.sup.2                                                  during injection   Species   %      kgf/cm.sup.2                         elongation %                                60° C.                                     90° C.                                         120° C.                                              150° C.                                                  molding__________________________________________________________________________Embodiment 7   Fatty acid ester 1             0.3    2490 2.09   35   25  15   10  LittleEmbodiment 8   Fatty acid ester 1             1.0    2430 2.04   30   20  10   10  LittleEmbodiment 9   Fatty acid ester 1             3.0    2370 1.99   25   15  10   5   LittleEmbodiment 10   Fatty acid ester 2             0.3    2500 2.11   30   20  15   8   LittleEmbodiment 11   Fatty acid ester 2             1.0    2430 2.08   25   15   8   5   LittleEmbodiment 12   Fatty acid ester 2             3.0    2380 2.00   20   10   5   3   Little__________________________________________________________________________Composition of ingredients in mixtureName of compound (additive)          %PPS; RYTON P-4 60-XGF; CS-03-MA-497          40Additive       XFatty acid ester 1: methyltripropanol stearic acid esterFatty acid ester 2: methyltripropanol montanic acid ester 
    
     
                                           TABLE 3__________________________________________________________________________                                 Dependence of model   Additive          Bending characteristics                                 resistor on metal                                                  Gas generated              Addition wt.                     Strength                          Fracture                                 temperature kgf/cm.sup.2                                                  during injection   Species    %      kgf/cm.sup.2                          elongation %                                 60° C.                                     90° C.                                          120° C.                                              150° C.                                                  molding__________________________________________________________________________Embodiment 13   Long-chain alcohol              0.3    2480 2.08   25  15   8   5   Little   phtalic acid ester 1Embodiment 14   Long-chain alcohol              1.0    2450 2.03   20  10   5   3   Little   phtalic acid ester 1Embodiment 15   Long-chain alcohol              3.0    2370 1.99   13   8   5   3   Little   phtalic acid ester 1Embodiment 16   Long-chain alcohol              0.3    2500 2.12   23  13   8   5   Little   phtalic acid ester 2Embodiment 17   Long-chain alcohol              1.0    2480 2.08   18   8   5   3   Little   phtalic acid ester 2Embodiment 18   Long-chain alcohol              3.0    2400 2.00   11   5   3   3   Little   phtalic acid ester 2__________________________________________________________________________Composition of ingredients in mixtureName of compound (additive)          %PPS; RYTON P-4 60-XGF; CS-03-MA-497          40Additive       XLong-chain alcohol phtalic acid ester 1: n = 28˜32Long-chain alcohol phtalic acid ester 2: n = 48˜52 
    
     
                                           TABLE 4__________________________________________________________________________                            Dependence of model  Additive      Bending characteristics                            resistor on metal mold                                                  Gas generated         Addition wt.                Strength                     Fracture                            temperature kgf/cm.sup.2                                                  during injection  Species         %      kgf/cm.sup.2                     elongation %                            60° C.                                  90° C.                                       120° C.                                             150° C.                                                  molding__________________________________________________________________________Example for  Not added         --     2480 2.04   &gt;500  &gt;500 &gt;500  &gt;500 Littlecomparison 1Example for  Zinc stearate         0.3    2140 1.90   200   150  110   95   Muchcomparison 2Example for  Olefin wax         3.0    2410 2.03   160   110  70    60   Littlecomparison 3Example for  Ester wax         0.3    2200 1.90   135   85   35    30   Muchcomparison 4Example for  PETS   0.3    2120 1.78    55   40   20    10   Muchcomparison 5Example for  PETS   1.0    2060 1.74    50   35   13     8   Muchcomparison 6__________________________________________________________________________Composition of ingredients in mixtureName of compound (additive)          %PPS; RYTON P-4 60-XGF; CS-03-MA-497          40Additive       XOlefin wax: polyethylene waxEster wax: Montanic acid ethylene glycol ester waxPETS: Abbreviation of pentaerythritol tetrastearate 
    
     Embodiments 19-24 
     Pellet samples of the composition prepared by adding various additives in the similar manner as in Embodiment 1 according to the mixing ratios shown in Table 5 were subjected to a molding process wherein a metallic mold having a sheet-type cavity of L=100 mm, D=25 mm, and t=1.6 mm is mounted on an injection molding machine (IS-50AM) with a clamping force of 50 tons (manufactured by Toshiba Machine Co., Ltd.). The pellet samples are molded under the following conditions: metallic mold temperature: 150° C.; cylinder temperature of the molding machine: 320° C.; injection pressure: 800 kgf/cm 2  ; injection time: 8s; and cooling time: 15s. The adhesive strength was then measured in accordance with JIS K 6856. The mechanical strength was measured by determining the bending characteristics in according with ASTM D 790. Molding flow length was determined by mounting a metallic mold with a 6.3×1.6 mmt cavity mounted on an injection molding machine (IS-50AM) with a clamping force of  50 tons manufactured by Toshiba Machine Co., Ltd) and by measuring spiral flow under the following conditions: metallic mold temperature: 150° C.; cylinder temperature in the molding machine: 320° C.; injection pressure: 980 kg/cm 2  ; injection time: 5s; and cooling time 15s. In addition, the surface wettability on the above-mentioned molding sheet was measured in terms of the contact angle for water 30s after touching by means of an Elmer goniometer contact-angle measuring instrument (model G-I) for room-temperature application. The results are shown in Table 5. 
     Embodiment 25-28 
     Various additives were compounded with PPS resin to prepare corresponding compositions in a pellet form as in Embodiments 19-24. These samples were subjected to tests similar to those in Embodiments 19-24. The results are shown in Table 6. 
     EXAMPLE FOR COMPARISON 7-13 
     Various additives were compounded with PPS resin to prepare corresponding compositions in a pellet form as in Embodiments 17-24. These samples were subjected to tests similar to those in the Embodiments 19-24. The results are shown in Table 7. 
     
                                           TABLE 5__________________________________________________________________________                             Adhesive strength                             (kgf) by   Additive compound                Bending characteristics                             species of adhesive                                        Spiral flow                                               Wettability of                                               surface         Addition wt.                Strength                      Fracture                             Silicone                                   Epoxy                                        characteristic                                               in terms of contact   Species         %      kgf/cm.sup.2                      elongation %                             adhesive                                   adhesive                                        cm     angle:__________________________________________________________________________                                               degreeEmbodiment 7   DPET-M         0.5    2430  2.15   68    68   65     53Embodiment 8   PPET-M         0.5    2440  2.16   70    68   53     57Embodiment 9   DPET-S         0.2    2460  2.12   60    63   51     60Embodiment 10   DPET-S         0.5    2430  2.11   65    65   53     59Embodiment 11   PPET-S         0.2    2470  2.15   60    65   50     60Embodiment 12   PPET-S         0.5    2450  2.15   68    65   53     58__________________________________________________________________________Mixing percentage of ingredientsName of compound     %PPS; RYTON P-4     60-XGF; CS-03-MA-497     40Additive compound     XDPET-M: Abbreviation for dipentaerythritol hexamontanate n = 2.0PPET-M: Abbreviation for polypentaerythritol montante n = 3.4(Esterification factor of montanic acid: 70%)DPET-S: Abbreviation for dipentaerythritol hexastearate n = 2.0PPET-S: Abbreviation for polypentaerythritol stearate n = 3.4(Esterification factor of stearic acid: 70%) 
    
     
                                           TABLE 6__________________________________________________________________________                                Adhesive strength                                (kgf) by          Wettability   Additive compound                    Bending characteristics                                species of adhesive                                           Spiral flow                                                  of surface in             Addition wt.                    Strength                         Fracture                                Silicone                                      Epoxy                                           characteristic                                                  terms of contact   Species   %      kgf/cm.sup.2                         elongation %                                adhesive                                      adhesive                                           cm     angle:__________________________________________________________________________                                                  degreeEmbodiment 7   Fatty acid ester 1             0.2    2490 2.09   62    50   65     53Embodiment 8   Fatty acid ester 2             0.5    2500 2.11   60    58   52     60Embodiment 9   Phthalic acid ester             0.2    2480 2.08   62    60   50     60   of long-chain   alcohol 1Embodiment 10   Phthalic acid ester             0.5    2500 2.10   60    58   52     60   of long-chain   alcohol2__________________________________________________________________________Mixing percentage of ingredientsName of compound     %PPS; RYTON P-4     60-XGF; CS-03-MA-497     40Additive compound     XFatty acid ester 1: methyltripropanolstearic acid ester m = 18Fatty acid ester 2: methyltripropanolmontanic acid ester m = 30Long-chain alcohol phtalic acid ester 1: n = 28˜32Long-chain alcohol phtalic acid ester 2: n = 48˜52 
    
     
                                           TABLE 7__________________________________________________________________________                               Adhesive strength                               (kgf) by         Wettability   Additive compound                   Bending characteristics                               species of adhesive                                         Spiral flow                                                of surface            Addition wt.                   Strength                        Fracture                               Silicone                                    Epoxy                                         characteristic                                                in terms of contact   Species  %      kgf/cm.sup.2                        elongation %                               adhesive                                    adhesive                                         cm     angle:__________________________________________________________________________                                                degreeExample for   Epoxy resin            1.0    2100 1.89    35  40   42     68comparison 7Example for   Silane compound            0.2    2400 2.05    20  25   46     74comparison 8Example for   Silane compound            0.5    2450 2.02    30  30   43     70comparison 9Example for   Zinc stearate            0.5    2090 1.87    40  40   49     63comparison 10Example for   Olefine wax            0.5    2380 2.00    25  25   52     75comparison 11Example for   PETS     0.2    2150 1.80    30  30   50     70comparison 12Example for   PETS     0.2    2100 1.75    40  35   52     68comparison 13__________________________________________________________________________Mixing percentage of ingredientsName of compound     %PPS; RYTON P-4     60-XGF; CS-03-MA-497     40Additive compound     XEpoxy resin: Dainippon Ink &amp; Chemicals, Inc. &#34;Epikuron 7050&#34;Silane compound: Epoxysilane (Nippon yunika K.K. &#34;NUC silane couplingagent A-187&#34;)Olefine wax: Polyethylene waxPETS: Abbreviation of pentaerythritol tetrastearateSilicone adhesive: Toshiba Silicone TSE-322 (Hardening condition =135° C./30 min)Epoxy adhesive: Dainippon Ink &amp; Chemicals, Inc. &#34;Two-component adhesive&lt;Epiklon 850/Lacamide EA240=50/50&gt;&#34;Hardening condition = 23° C. for 1 h and 100° C. for 1 h)