MXPA98003165A - Composition of polyace resin - Google Patents

Abstract

A polyacetal resin composition having excellent properties such as a hinge and improved fluidity is provided without detriment to the mechanical properties, the friction and abrasion resistance, the molding ability and the inherent stiffness of the polyacetal; The polyacetal resin is further characterized in that it comprises an initial polymer mixture composed of a polyacetal resin and a core / shell polymer comprising vitreous, and containing a saturated fatty acid bisamide as the lubricant, homogeneously mixed with the same.

Description

COMPOSITION OF POLYACETAL RESIN FIELD OF THE INVENTION The present invention relates to a polyacetal resin composition that is prepared by mixing a polyacetal resin with a specific core / shell polymer and which has a very satisfactory hinge characteristic and is excellent in impact and flow resistance; and to a hinge part made with polyacetal resin obtained by molding the above composition. The hinge part described above is, for example, one as shown in Figure 1, and a thin-walled portion to which a bending or bending load is applied one or more times in a certain portion of the part is called the hinge (shown with number 1 in the drawing). The shape of the hinge should not be specifically restricted and may be in the form of a sheet, strip shape and strip shape. Nor should the thickness and length of the hinge be specifically restricted. An article that substantially has a hinge function is included in the hinge part related to the present invention. In the present invention, the hinge feature is defined by a durability against a bending or bending load one or more times in the hinge, as described above.

RELATED TECHNIQUE As is well known, a polyacetal resin has been used in many areas in recent years, such as an engineering resin that is excellent in physical characteristics such as mechanical properties and electrical properties, and in chemical characteristics such as chemical resistance and heat resistance. . However, as the areas in which the polyacetal resin is used are expanded, in some cases specific additional properties are required to the properties thereof as a material. In certain cases the development of materials having an excellent flexural property is desired as one of those properties, that is, materials that have an excellent hinge characteristic. Particularly in recent years, the need to reduce costs has increased more and more, cutting the number of parts to integrate some parts by means of a hinge to install them easily at a low cost. In addition, a substantially excellent hinge feature has been more strictly required because there are many factors to reduce a hinge feature such as the use of hinge parts at low temperatures and the impossibility of having an adequate hinge shape in terms of structure. In addition, in the areas of electrical articles and building materials, the possibilities of using various materials by combining them according to the objects thereof are also growing, and a resistance to the impact of the polyacetal resin is required to increase them further. The methods in which elastomers such as thermoplastic polyurethane are added to a polyacetal resin to try to improve the hinge characteristic or impact resistance, are known as a method to satisfy the requirements of the hinge feature. The hinge feature can also be improved by this method, but there is a problem that the bending of an elastomer component promotes the origination of a peeling phenomenon on the surface of the molded article, markedly damaging the appearance of the molded article. In addition, there are several problems because the stability to heat is reduced and the resistance to welding and to the elongation of the molded article are markedly diminished, and because the fluidity is also reduced, and therefore the degree of freedom to design a hinge is diminished. Consequently, it has been desired to improve this. In addition, by increasing the functions required for a hinge in recent years, the shape of the hinge is complicated and the wall thereof becomes thinner for the purposes of cutting costs and reducing weight. To increase productivity in injection molding, it is required to shorten a molding cycle and carry out molding with several dies, to thereby increase the number of molded articles obtained by an injection molding operation. To satisfy these requirements, an improvement in the material is necessary to obtain a high fluidity.

DESCRIPTION OF THE INVENTION An object of the present invention is to provide a polyacetal resin composition having much better hinge characteristics than conventional ones, without damaging the other physical properties, and providing a hinge part made with a polyacetal resin. The present inventor continued intensive investigations to solve the problems described above by sacrificing as little as possible the inherent characteristics of the polyacetal resin and developing a polyacetal material having an excellent hinge characteristic, while maintaining rigidity. As a result of this, he has discovered that a resin obtained by homogenously mixing a core / shell polymer with a specific saturated fatty acid bisamide added effectively, and thus has succeeded in completing the present invention. That is, the present invention relates to a polyacetal resin composition comprising: (A) 100 parts by weight of a polyacetal resin and (B) 1 to 100 parts by weight of a core / shell polymer comprising a a polymeric polymer core and a vitreous polymer shell and containing 0.3 to 5 parts by weight (per 100 parts by weight of the core / shell polymer) of a saturated fatty acid bisamide of the following general formula, homogenously mixed therewith : general formula: R? -CONH-R2 -NHCO-R2 where R? and R3 may be the same or different from each other and each represents a group selected from aliphatic alkyl, substituted alkyl, aryl and substituted aryl groups having 10 to 22 carbon atoms, and R2 represents a divalent hydrocarbon group having 1 to 20 carbon atoms. to 12 carbon atoms; and a hinge part made with polyacetal resin obtained by molding the above polyacetal resin composition. The resin composition of the present invention contains (A) and (LB) as described above, and (B) contains the core / shell polymer and the saturated fatty acid bisamide described above. Both mix well. This is a very suitable material as a resin for a hinge because it is provided with a hinge characteristic, satisfactory impact resistance and fluidity, which have been difficult to obtain. As described above, the resin composition of the present invention, prepared by homogeneously mixing the core / shell polymer with the specific lubricant (saturated fatty acid bisamide) and kneading it with the polyacetal resin, shows the marked effects of being excellent in a characteristic of hinge and fluidity, and maintains rigidity, counting at the same time with the well-balanced mechanical properties of polyacetal. The hinge part obtained by molding said polyacetal resin composition is used as various hinge parts in automobiles, electrical and electronics, construction materials and miscellaneous goods areas, more specifically, in automotive connectors, connectors for electrical articles and the like, and the polyacetal resin composition is suitably used for these purposes.

BRIEF DESCRIPTION OF THE DRAWING Figure 1 is a schematic drawing of a test piece used to measure the hinge feature, and (a), (b) and (c) show a plan view, a side view and an elongated view of the hinge part , respectively. The unit of other numbers is mm.

DETAILED DESCRIPTION OF THE INVENTION Next, the structural components of the present invention will be explained in detail. First, the polyacetal resin (A) used in the present invention is a high molecular weight compound having an oxymethylene group (-CH2O-) as a major structural unit, and can be any of a polyoxymethylene homopolymer and a copolymer, a terpolymer and a block copolymer, each having small amounts of other structural units in addition to the oxymethylene group, or it may be one in which the molecule has a branched or interlaced structure, as well as a linear structure. In the present invention, the polyacetal resin having a melt index of 0.2 to 30 g / 10 minutes, still preferably 0.5 to 15 g / 10 minutes, which is determined according to an ASTIi method D1238-89E at a cylinder temperature of 190 ° C. Next, the core / shell polymer (B) used in the present invention is obtained by homogeneously mixing the core / shell polymer having a core of polymerized polymer and a vitreous polymer shell with 0.3 to 5 parts by weight (per 100 parts). by weight of the core / shell polymer) of the saturated fatty acid bisamide represented by the following general formula: general formula: Ri -CONH-R2 -NHCO-R3 wherein Ri and R3 may be the same or different from each other and each represents a group selected from aliphatic alkyl, substituted alkyl, aryl and substituted aryl groups having 10 to 22 carbon atoms, and R 2 represents a divalent hydrocarbon group having 1 to 12 carbon atoms. The core / shell polymer used as a precursor for the core / shell polymer (B) homogeneously blended with the saturated fatty acid bisamide used in the present invention, is a composite having a core of polymerized polymer and a polymer shell. vitreous. It can be prepared by known methods or commercially available products can also be used. Typical examples thereof include Acryloid KM330 and KM653, manufactured by Rohm & amp;; Haas Co., Ltd., Paraloid KCA-102 and KCA-301, manufactured by Kureha Kagaku KK, Stafiloid PO-0143 and PO-01 8, manufactured by Takeda Yakuhin Kogyo KK, Kaneace FM, manufactured by Kanegafuchi Kagaku Kogyo KK, and Metablen C-102, E-901, W-800 and S-2001, manufactured by Mitsubishi Reiyon KK.One of these core / shell polymers, core / shell polymers having a polymer-coated core and a shell are preferred. vitreous polymer comprising methyl methacrylate as a main component, and core / shell polymers in which no anions are substantially detected are particularly preferred. If the core / shell polymers in which anions are detected are used, it is possible that the decomposition of the polyacetal is accelerated in melting and kneading and in injection molding; and that the desired hinge feature is not obtained. In addition, the decomposition is such that fusion and kneading are impossible in some cases. The core / shell polymer in which anions are not substantially detected means a core / shell polymer in which anions are not detected by a conventional qualitative test. For example, the presence of anions can be confirmed by measurement methods such as a method in which 5 g of a sample (core polymer / shell) is weighted in a 50 ml conical flask; 20 ml of water with exchanged ions is added; the stirring is continued for 3 hours with a magnetic stirrer and then the filtrate obtained by carrying out the filtration through a filter paper number 5C is divided into two portions, and 0.5 ml of an aqueous solution of barium chloride 1% is added to a portion to compare the presence of turbidity by observation (qualitative test of a sulfur ion), and by a method in which the same procedure is carried out, except that an aqueous solution of nitrate is added. 0.1 N silver instead of the aqueous 1% barium chloride solution to compare the presence of turbidity (qualitative test of halogen ions). Preferably, the core / shell polymer in which these anions are not present at all is suitably used. The core / shell polymer preferably used in the present invention is obtained by carrying out the emulsion polymerization in the presence of a nonionic surfactant and a polymerization initiator, yielding neutral radicals. Said core / shell polymer can be produced by means of an emulsion polymerization technique described in, for example, JP-A-2-14856. The emulsion polymerization can be carried out in the presence of, for example, the following surfactant and a polymerization initiator. Almost any of the broad and commonly used nonionic surfactants can be used as the nonionic surfactant, including the ether types such as polyoxyethylene nonylphenyl ether, polyoxyethylene stearyl ether and polyoxyethylene lauryl ether, ester types such as polyoxyethylene monostearate, sorbitan ester types such as polyoxyethylene sorbitan-onolaurate and block polymer types such as a polyoxyethylene-polyoxypropylene block copolymer. The amount of addition thereof is suitably selected according to the grain stabilization capacity of the surfactant. The azo-base polymerization initiators, such as azobisisobutyronitrile, dimethyl 2,2'-azobisisobutyrate and 2,2'-azobis dihydrochloride (2) are used as the polymerization initiator alone or in combination with two or more types thereof. -aminopropane), and hydroperoxide-based polymerization initiators such as eumeno hydroperoxide, diisopropylbenzene hydroperoxide, and hydrogen peroxide. In this way, if the emulsion polymerization is carried out in a reaction system of a surfactant system that does not contain anions and is not persulphate, a core / shell polymer is obtained which contains substantially no anions or which contains only a small amount of these. The polyacetal resin composition using said core / shell polymer and which does not contain anions substantially is excellent in hinge characteristics. The core / shell polymer used as a precursor in the present invention has a rubberized polymer core and a vitreous polymer shell, and is obtained by a continuous, multi-stage emulsion polymerization method in which a polymer obtained in a Initial stage is usually covered with polymers obtained in later stages, among seed emulsion polymerization methods. In case the core / shell polymer has an intermediate phase which will be described later, the middle phase is formed in some case by said multi-stage emulsion polymerization method in which the polymer obtained in a later stage penetrates a polymer obtained in an initial stage. In the polymerization to produce grains, the emulsion polymerization reaction is preferably initiated by adding the monomer, the surfactant and water to a reactor, and then further adding the polymerization initiator thereto. The polymerization in the first stage is the reaction to form a rubbery polymer. The monomer constituting the rubberized polymer includes, for example, conjugated diene or alkyl acrylate in which the alkyl group has 2 to 8 carbon atoms, or a mixture thereof. These monomers are polymerized to form the rubberized polymer having a glass transition temperature of -30 ° C or less. Said conjugated diene includes, for example, butadiene, isoprene and cyoroprene. In addition, the alkyl acrylate in which an alkyl group has 2 to 8 carbon atoms includes, for example, ethyl acrylate, propyl acrylate, butyl acrylate, cyclohexyl acrylate, and 2-ethylhexyl acrylate. Copolymerizable monomers copolymerizable with the conjugated diene and the alkyl acrylate can be copolymerized in the polymerization during the first stage, for example, aromatic vinyls such as styrene, vinyltoluene and cx-methylstyrene, aromatic vinylidene, vinyl cyanides such as acrylonitrile and methacrylonitrile. , vinylidene cyanide and alkyl methacrylates such as methyl methacrylate and butyl methacrylate. When the conjugated diene is not contained in the polymerization during the first stage or, if contained, it amounts to 20% by weight or less, based on the total amount of monomer used in the first stage, obtaining a polymer having a high Impact resistance using a small amount of an entanglement monomer and a graft monomer. The crosslinking monomer includes, for example, aromatic divinyl monomers such as divinylbenzene and polyol polyacrylates of alkane or polyol polyol achacrylate ethers such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, butylene glycol diacrylate, hexanediol diacrylate, hexanediol dimethacrylate, oligoethylene glycol diacrylate. , oligoethylene glycol dimethacrylate, trimethylolpropane diacrylate, trimethylolpropane dimethacrylate, trimethylolpropane triacrylate and trimethylolpropane trimethacrylate. In particular, butylene glycol diacrylate and hexanediol diacrylate are preferably used. The graft monomer includes, for example, allylic esters of unsaturated carboxylic acid such as allyl acrylate, allyl methacrylate, diallyl maleate, diallyl fumarate and diallyl itaconate. In particular, allyl methacrylate is preferably used. Said entanglement monomers and graft monomers are used on a scale of 0 to 5% by weight, preferably 0.1 to 2% by weight, based on the total amount of monomer used in the first stage. The core of this rubberized polymer is preferably on a scale of 50 to 90% by weight, based on the total amount of the core / shell polymer. When the core is on a scale lower or higher than this weight scale, the resin composition obtained by melting and mixing the resulting core / shell polymer does not provide a satisfactory effect to improve the impact strength in a certain case. In addition, when the core has a glass transition temperature of more than -30 ° C, in some cases a satisfactory effect is not provided to improve impact resistance at low temperatures. The vitreous polymer is formed in the outermost shell layer (shell phase). The monomers constituting the vitreous polymer include methyl methacrylate and a mixture of copolymerizable monomers with methyl methacrylate, and form the vitreous polymer having a glass transition temperature of 60 ° C or more. Monomers copolymerizable with methyl methacrylate include, for example, vinyl polymerizable monomers including alkyl methacrylates such as ethyl methacrylate and butyl methacrylate, alkyl acrylates such as ethyl acrylate and butyl acrylate, aromatic vinyls such as styrene, vinyl toluene and α-methylstyrene, aromatic vinylidenes, vinyl cyanides such as acrylonitrile and methacrylonitrile, and vinylidene cyanides. In particular, ethyl acrylate, styrene and acrylonitrile are preferably used. The outermost shell layer (shell phase) is preferably on a scale of 10 to 50% by weight, based on the total amount of the core / shell polymer. When this shell phase is on a scale lower or higher than the given scale, the resin composition obtained by melting and mixing the resulting core / shell polymer does not provide a satisfactory effect to improve the impact strength in a certain case. In addition, an intermediate phase may be present between the polymerized phases formed in the first and last stages. The intermediate phase is formed by seed emulsion polymerization, for example, polymerizable monomers having functional groups such as glycidyl methacrylate, methacrylic acid and hydroxyethyl methacrylate, polymerizable monomers which form vitreous polymers such as methyl methacrylate, and polymerizable monomers which they form rubbery polymers such as methyl acrylate. Said intermediate phase can be selected from several of these, according to the properties of the desired core / shell polymer. The polymerization ratio thereof can be suitably selected according to the monomers used. For example, when the vitreous polymer is used for the intermediate phase, the polymerization ratio thereof can be calculated as a part of the shell, and in the case of the rubberized polymer, it can be calculated as part of the core. The structure of the core / shell polymer having said intermediate phase includes a multilayer structure in which another layer is present between the core and the shell, and a salami structure in which an intermediate phase is dispersed in the core at fine grain shape. In the core / shell polymer having the salami structure, the intermediate phase that will be dispersed sometimes forms a new core in the central part of the core in an extreme case. The core / shell polymer having said structure occurs in a certain case when a monomer represented by styrene is used as a monomer to constitute the intermediate phase. In addition, when the polymer of a core / shell having the intermediate phase is used, it is possible in a certain case that the impact resistance is improved and that the elastic modulus of bending is increased, as well as that the temperature of thermal deformation is high and the appearance (surface peeling, an inhibition of the pearlescent sheen and a change in the color tone caused by the change in the refractive factor) is improved. As a method to provide a polyacetal resin with impact resistance, a method has been known so far in which a core / shell polymer is added to a polyacetal resin, excluding a method in which a rubberized material is added. This method certainly satisfies the conditions that are different from the hinge characteristics, but has the defect that while a polyacetal resin has an inherently lower hinge characteristic, the addition of the core / shell polymer results in an extra reduction of the hinge feature. Heretofore, a polyacetal resin having a satisfactory hinge characteristic while maintaining fluidity and a non-peeling property has not been provided. In this way, the addition and mixing of a conventional core / shell polymer to a polyacetal resin has made the hinge feature quite inferior, while increasing the rigidity without diminishing the excellent mechanical properties of the polyacetal resin, and therefore it has made it impossible to use the polyacetal resin for hinge parts. Accordingly, the present invention is characterized by kneading a polyacetal resin (A) with a component (B) obtained by mixing the core / shell polymer component described above with the specific lubricant (saturated fatty acid bisamide). Mixing the two components (A) and (B) by said method is very effective in improving the hinge feature without damaging the well-balanced characteristics inherent in the polyacetal resin. A method for mixing three components of the polyacetal resin, the core / shell polymer and the lubricant, includes a method in which any two components are kneaded and then the remaining component is added to continue the kneading, and a method in the which the three components are kneaded at the same time. In a method in which, for example, the polyacetal resin and the core / shell polymer are kneaded and then the lubricant is added to continue the kneading, an influence exerted by the lubricant degrades a kneading condition and also impairs the capacity of dispersion of the lubricant, and therefore the resulting polyacetal resin composition has a lower homogeneity. As a result of this, a hinge part obtained by molding the polyacetal resin composition thus obtained is lower in a hinge function, and therefore said method is not preferred. Another method includes a method in which the polyacetal resin and lubricant are kneaded and then the core / shell polymer is added to continue the kneading. However, the polyacetal resin containing the lubricant is kneaded with the core / shell polymer, and therefore it is difficult for the core / shell polymer to be uniformly dispersed, whereby a hinge part obtained by molding the composition of polyacetal resin thus obtained is also inferior in its function as a hinge, and therefore said method is not preferred. Furthermore, even if the three components are kneaded at the same time, the hinge part obtained by molding the polyacetal resin composition thus obtained is lower in a hinge function similarly to the methods described above, and therefore said method does not It preferred. Even if these three components are kneaded by any of the methods described above, the core / shell polymer and the lubricant have poor dispersibility and are lower in homogeneity in the obtained polyacetal resin composition. Consequently, a hinge part obtained by molding the polyacetal resin composition thus obtained is also inferior in its function as a hinge, and therefore said methods are not preferred. However, the present inventor has discovered that a method in which the saturated fatty acid bisamide is homogenously mixed with the core / shell polymer and this is added to the polyacetal resin is effective for a hinge part. In the present invention, the polymer mixed with the polyacetal resin is the core / shell polymer containing lubricant obtained by homogenously mixing the core / shell polymer with the total amount of the lubricant to be mixed with the polyacetal resin composition. The saturated fatty acid bisamide can be homogeneously dispersed in the core / shell polymer using, for example, a method in which a solution obtained by dissolving saturated fatty acid bisamide in a solvent is mixed with a core / shell polymer commercially available. means of a Henshell mixer and then the solvent is removed, or a method in which the saturated fatty acid bisamide is added in the drying step in the emulsion polymerization of a core / shell polymer. The saturated fatty acid bisamide used for said purpose of the present invention is represented by the following general formula: general formula: R? -CONH-R2 -NHCO-R3 wherein Ri and R3 may be the same or different from each other and each represents a group selected from aliphatic alkyl, substituted alkyl, aryl and substituted aryl groups having 10 to 22 carbon atoms , and R2 represents a divalent hydrocarbon group having 1 to 12 carbon atoms. This is obtained from a specific alkylene diamine and a specific saturated fatty acid. The saturated fatty acid component of the saturated fatty acid bisamide has 11 to 23 carbon atoms and includes undecanoic acid, lauric acid, tridecanoic acid, ironic acid, pentadecanoic acid, palmitic acid, argaric acid, stearic acid, nonadecanoic acid, acid arachidic and behenic acid. Among these, stearic acid is particularly preferred. The divalent hydrocarbon group of the saturated fatty acid bisamide preferably includes alkylene groups such as onomethylene, dimethylene, trimethylene, tetramethylene, pentamethylene and hexamethylene. Among these, monomethylene and dimethylene are particularly preferred. Among the saturated fatty acid esters described above, ethylene bis stearic acid amide (C17H35-CONH-CH2-CH2-NHCO-C17H35) and methylenebistearoic acid amide (C17H35-CONH-CH2-NHCO-C17H35) are particularly preferred. The amount of addition of the saturated fatty acid bisamide is suitably from 0.3 to 5 parts by weight, preferably 1 to 5 parts by weight and particularly from 2 to 4 parts by weight, per 100 parts by weight of the core / shell polymer. The amount of less than 0.3 parts by weight reduces the effect of improving the hinge feature, and the amount of more than 5 parts by weight saturates the effect of improvement and exerts an adverse effect on the characteristics inherent to the polyacetal resin. The kneading / mixing of said saturated fatty acid bisamide with the polyacetal resin (A) and with the core / shell polymer, provides a polyacetal resin composition that has excellent rigidity but does not provide the molded hinge part that It has an excellent hinge feature. However, the marked improvement effect is displayed and the effect provided by the excellent hinge feature is observed by mixing the core / shell polymer before with the saturated fatty acid bisamide. In a molded article obtained by adding and mixing the core / shell polymer in the polyacetal resin, the core / shell polymer is dispersed on the surface thereof in the form of grains, and when the molded article is bent, it is broken or broken. broken, the core / shell polymer being an origin. Accordingly, the composition obtained by mixing the polyacetal resin (A) with the core / shell polymer is inferior in a largely hinge feature. However, the marked improvement effect is displayed and the effect that provides an excellent hinge characteristic is observed by mixing the core / shell polymer before with the saturated fatty acid bisamide. It is established that said actions and effects are due to the fact that since even the core / shell polymer comprising primary grains of certain μ is normally coagulated in secondary grains of about 10 μm, and that the mere fact of kneading it with the polyacetal resin does not allow the core / shell polymer to be homogenously dispersed in primary grains, but mixing the core / shell polymer before with the saturated fatty acid bisamide allows the polymer to be homogeneously dispersed. core / shell is homogenously dispersed in primary grains when it is kneaded with the polyacetal resin. The great effect of this provided using the saturated fatty acid bisamide as a lubricant is established to be due to the fact that the great affinity thereof for the shell component of the core / shell polymer, raises the ability to disperse the core polymer /breastplate. These actions and effects are not necessarily definitive, and the present invention should not be restricted in any way by this. The addition amount of the core / shell polymer (B) mixed with the saturated fatty acid bisamide according to the present invention is 100 parts by weight, preferably 5 to 50 parts by weight, per 100 parts by weight of the polyacetal resin. A very small addition amount of the core / shell polymer does not allow the hinge feature and impact resistance to be deployed satisfactorily, and a very excessive amount reduces the mechanical properties, particularly the rigidity in large part, and exerts a unfavorable effect on heat stability.

In addition, various stabilizing agents known to the composition of the present invention are preferably added to enhance the heat stability. For this purpose, preferably known antioxidants, nitrogen containing compounds and alkali metal or alkaline earth metal compounds are used, alone or in combination of two or more types thereof. In addition, to provide the composition of the present invention with the desired characteristics according to the purposes thereof, known additives may be added, for example, lubricants other than saturated fatty acid bisamides, nucleating agents, release agents, antistatic agents, other surfactants, high molecular weight organic materials and fibrous, granular or tabular fillers, organic or inorganic, alone or in combination of two or more types thereof. The composition of the present invention can be prepared in facilities and methods that are generally known as methods for preparing synthetic resin compositions. That is, the necessary components are mixed, kneaded and extruded by means of an extruder machine of one or two worms to form molding pellets, and then the pellets can be used for molding. Alternatively, the composition can be prepared at the same time as molding in a molding machine. Furthermore, a method is available in which, to improve the dispersion and mixing of the respective components, part or all of the resin component is pulverized, mixed, melted and extruded to form pellets. Any of the above methods can be used. Materials such as stabilizing agents and additives, each described above, can be added at any stage, and it is a matter of course that they can be added and mixed just before obtaining the finished molded article. The resin composition according to the present invention can be molded by any method of extrusion molding, injection molding, compression molding, vacuum molding, blow molding and foaming. .

EXAMPLES The present invention will now be explained with reference to examples and comparative examples, but the present invention should not, for any reason, be restricted by these examples. The "parts" shown in the examples and in the comparative examples represent parts by weight. The abbreviations used in the examples and in the comparative examples are as follows: Ethyl Acrylate EA MMA methacrylate MMA 1,4-butylene glycol BGA acrylate Alim methacrylate AIMA Metac rilamide MAM 2-ethylhexyl acrylate EHA Butadiene BD Nonionic surfactant (E algen 950 E95 0 manufactured by Kao Corporation) Anionic surfactant Agent surfactant oligomer type A (synthesized according to the description of Example 13 in JP-A-53-10682 and controlled to a solids content of 10% by demineralized water after adjusting to a pH of 7.5 with aqueous ammonia). n-Dodecil-S- where a: b = 7: 3, and a + b = approximately 13.6.

Composition: Methacrylic acid 155 g MMA 360 g n-Dodecyl mercaptan 109 g Azobisisobuti roni t ril 4.4 g Isop ropanol 314 g Molecular weight r 1310 Deionized water DI Diclo 2, 2 '-azobis (2-aminop ropano) V50 (V50 manufactured by Wako Junyaku) Etilenbisestearoamide EBS C17 H-35 -CONH-CH2CH2 -NHCO-Ci -H35 Methylenebisestearoamide MBS C17 H-35 -CONH-CH -NHCO-Ci -H35 Tet restea pentaerythritol time PETS Polyacetal resin POM resin Production of core / shell polymers Bl and B'-l: A polymerization vessel equipped with a 5-liter reflux condenser was charged with 1200 g of DIW, 1.68 g of 25% aqueous ammonia, 7 g of surfactant A and 0.14 g of MAM, and the temperature was raised to 70 ° C by stirring under nitrogen flow. 27.86 g of a seed monomer mixture having the following composition was added., and the mixture was dispersed for a period of 10 minutes. Then, 21 g of a 10% aqueous solution of V50 were added to polymerize the seed grains. Seed monomer: EA 27.664 g AIMA 0.14 g BGA 0.056 g Subsequently, 7 g of MAM was added and a monomer emulsion was obtained by adding and mixing 1500 g of a core part monomer mixture having the following composition with 210 g of surfactant A, 900 g of DIW and 2.80 of 25% aqueous ammonia and a mixed liquid of 21.0 g of an aqueous solution of V50 at 10% and 0.63 g of aqueous ammonia at 1% were fed continuously for a period of 180 hours. minutes to carry out seed polymerization. Monomer mixture of core part: EHA 1040.2 g BD 450.0 g BGA 2.8 g AIMA 7.0 g The temperature was raised to 80 ° C to mature the solution for one hour, and then it was cooled to 70 ° C. Then, 9 g of a 10% V50 aqueous solution and 0.27 g of 1% aqueous ammonia were added, and a shell part monomer emulsion having the following composition, 12 g of 10% aqueous solution of V50. and 0.36 g of 1% aqueous ammonia were fed continuously for a period of 60 minutes to carry out the emulsion polymerization. Coating part monomer mixture: MMA 438.8 g EA 60.0 g Surfactant 30.0 g DIW 500.0 g 25% aqueous ammonia 0.72 g BGA 1.2 g MAM 3.0 g The temperature was raised to 80 ° C to mature the solution for one hour and then it was cooled. The solution was filtered through a 300 mesh wire gauze to obtain a core / shell polymer latex. This latex was frozen at -15 ° C and filtered through a glass filter. The jet drying was then carried out at 60 ° C for 24 hours to obtain a core / shell polymer B'-1. This core / shell polymer was mixed with a solution obtained by dissolving 60 g of ethylene bis stearic acid amide (trade name: Armowax, manufactured by Lion Akzo Co., Ltd.) in 100 ml of DMF by means of a Henshell mixer, and then the solvent was removed under reduced pressure to obtain a core / shell polymer Bl.

Production of core / shell polymers B-2 to 5 and B '-2 to 3. The polymerization was carried out in the same way as in Bl to obtain core / shell polymers B-2 to 5 and B'- 2 to 3, but the monomers having the compositions shown in the table were used.

Production of core / shell polymer B * -4. The polymerization was carried out in the same manner as in B-1 to obtain the core / shell polymer B'-4, but the monomers having the compositions shown in Table 1 were used and the lubricant was not added.

TABLE 1 [Qualitative test of sulfuric acid ion]. The sulfuric acid ions contained in the core / shell polymers Bl a 5 and B'-la 4 were detected. That is, 5 g of the sample were weighed into a 50 ml conical flask, and 20 ml of deionized water were additives to continue the agitation for 3 hours by means of a magnetic stirrer. Then, a filtrate obtained by filtering the solution through a filter paper No. 5C was divided into two portions and 0.5 ml of an aqueous solution of 1% barium chloride was added to one portion to compare and observe the generation of turbidity . In the present qualitative test no sulfuric acid ions were detected from core / shell polymers Bl a 5 and B'-la 4. Polyacetal: POM copolymer resin, trade name Duracon, manufactured by Polyplastics Co., Ltd. At the melt index (190 ° C): 2.5 (g / 10 minutes). A-2 melt index (190 ° C): 9.0 (g / 10 minutes).

EXAMPLES 1 TO 8 The Duracon POM copolymer resin manufactured by Poliplastics Co., Ltd. and the core / shell polymers Bl a 5 produced in the above manner mixed in the compositions shown in Table 2 were dried to a water content of 0.3% or less and then melted and kneaded by means of an extruder machine of two worms PCM-30 manufactured by Ikegai Tekko KK at a cylinder temperature of 190 ° C and at a die head temperature of 200 ° C to pelletize them. This pellet was dried at 80 ° C for 3 hours or more, and molded by means of an injection molding machine to prepare a test piece, and the following evaluations were carried out. The results of these are shown in table 2.

COMPARATIVE EXAMPLES 1 TO 11 The Duracon POM copolymer resin manufactured by Polyplastics co., Ltd. and the core / shell polymers B'-la 4 produced in the above form mixed in the compositions shown in Table 3 were dried to a high content. of water of 0.3% or less and then melted and kneaded by means of the PCM-30 twoworm extruder machine manufactured by Ikegai Tekko KK at a cylinder temperature of 190 ° C and at a die head temperature of 200 ° C to pelletize them. This pellet was used to prepare a test piece, in the same way as in the previous examples to carry out the following evaluations. The results of these are shown in table 3. "The feature evaluations in the examples and in the comparative examples were carried out according to the following methods. (1) Evaluation of the hinge characteristic A test piece having a shape shown in figure 1 was molded and then evaluated based on the parameters shown below: Sample number: n = 10 Test method: the sample was allowed to stand under an ambient of -10 ° C and 50% RH for 24 hours or more, and then the hinge part was repeatedly bent 100 times at an angle of 180 ° C under the same conditions as those described above.

Evaluation A: number of hinge parts broken while bending 100 times (the smaller the number, the more excellent). Evaluation B: the condition of the hinge parts after doubling 100 times was evaluated according to the following judgment parameters and shown by an average point (the higher the value, the more excellent). 5: Barely and something unusual was observed. 4: Fine cracks were produced on the surface of the hinge part. 3: The cracks produced on the surface of the hinge part became larger. 2: The cracks produced on the hinge part grew more toward the central part, so the hinge part became very thin. 1: The part of the hinge that became thin had a cut line and almost broke. 0: It broke. (2) Izod Impact Resistance The resin pellets prepared in the examples and in the comparative examples were molded to form test samples (rectangular parallelepiped with a width of 12.7 mm, a thickness of 6.4 mm and a length of 64 mm) by means of an inline injection molding machine, and they were grooved according to the method of ASTM D 256 to determine the Izod impact values. It is judged that the higher the Izod impact value, the better. In the examples, a method for molding test pieces used to evaluate a hinge characteristic and mechanical properties is as follows: * Molding machine: IS80 manufactured by Toshiba K.K. * Molding conditions: Cl C2 C3 nozzle Cylinder temperature (° C) 200 190 180 160 Injection pressure '650 (kg / cm2) Injection speed 11.0 (m / min) Die temperature 70 (° C) (3) Flow measurement method (flow length adhered to a thin wall) A thin-walled test piece (width 5 mm X thickness 0.5 mm) was molded by a molding machine programmed to the following conditions, and evaluated the fluidity from the flow length thereof (length at which the resin was filled). * Molding machine: PS200E manufactured by Nissei K.K. * Molding conditions: Cl C2 C3 nozzle Cylinder temperature (° C) 200 190 180 160 Injection pressure 1000 (kg / cm2) Injection speed 4.0 (m / min) Die temperature 70 (° C) TABLE 2 TABLE 3

Claims (8)

NOVELTY OF THE INVENTION CLAIMS

1. - A polyacetal resin composition comprising: (A) 100 parts by weight of a polyacetal resin and (B) 1 to 100 parts by weight of a core / shell polymer comprising a core of rubberized polymer and a shell of vitreous polymer and containing 0.3 to 5 parts by weight (per 100 parts by weight of the core / shell polymer) of a saturated fatty acid bisamide of the following general formula homogeneously mixed therewith previously: R1-C0NH-R2-- NHCO-R3, wherein Ri and R3 may be the same or different from each other and each represents a group selected from aliphatic alkyl, substituted alkyl, aryl and substituted aryl groups having from 10 to 22 carbon atoms, and R2 represents a divalent hydrocarbon group having 1 to 12 carbon atoms.

2. The polyacetal resin composition according to claim 1, further characterized in that the core / shell polymer (B) is one in which no anion is substantially detected.

3. The polyacetal resin composition according to claim 1 or 2, further characterized in that the core / shell polymer (B) is obtained by the emulsion polymerization carried out in the presence of a nonionic surfactant and of a polymerization initiator that forms a neutral free radical.

4. The polyacetal resin composition according to any of claims 1 to 3, further characterized in that the shell of the core / shell polymer (B) comprises a polymer comprising mainly methyl methacrylate.

5. The polyacetal resin composition according to any of claims 1 to 4, further characterized in that the saturated fatty acid amide component of the saturated fatty acid bisamide is selected from undecanoic, lauric, tridecanoic, ironic acids , pentadencanoic, palmitic, margaric, stearic, nonadecanoic, arachidic and behenic

6. The polyacetal resin composition according to any of claims 1 to 4, further characterized in that the divalent hydrocarbon group of the saturated fatty acid bisamide is selected between monomethylene, dimethylene, trimethylene, tetramethylene, pentamethylene and hexamethylene groups.

7. The polyacetal resin composition according to any of claims 1 to 4, further characterized in that the saturated fatty acid bisamide is ethylenebistearamide (C17H35-CONH-CH2-CH2-NHCO-C17H35) and / or methylenebistearamide (C17H3S) -CONH-CH2 -NHCO-C17H35).

8. A hinge part of polyacetal resin produced by molding the polyacetal resin composition set forth in any of claims 1 to 7.