KR100475401B1 - Polyacetal resin composition - Google Patents

Abstract

The present invention provides a polyacetal resin composition having excellent hinge properties and improved fluidity while retaining mechanical properties, frictional wear, moldability, toughness, etc. inherent in polyacetal.

In addition, the present invention provides a polyacetal resin composition characterized by polymerizing and blending a core / shell polymer having a rubbery polymer core and a glassy polymer shell into a polyacetal resin, in which a saturated fatty acid bisamide is uniformly blended in advance with a lubricant. do.

Description

Polyacetal Resin Composition {POLYACETAL RESIN COMPOSITION}

The present invention provides a polyacetal resin composition prepared by mixing a polyacetal resin and a specific core / shell polymer, having a very excellent hinge property, and having excellent impact resistance and fluidity, and a polyacetal resin obtained by molding the composition. It is related with the manufactured hinge part.

The above-mentioned hinge part is as shown, for example, in FIG. 1, and a thin wall part to which a bending or folding load is applied at least once to a part of the part is called a hinge (indicated by reference numeral 1 in the drawing). . The shape of the hinge is not particularly limited and may be a sheet type, a band shape and a string shape. The thickness or length of the hinge is also not limited. Substantially hinged products are included in the hinge part according to the invention.

In the present invention, the hinge characteristic is defined as the durability against one or more bending or folding loads in the hinge as described above.

As is well known, polyacetal resins have recently been used in a wide range of fields as engineering resins and are excellent in chemical properties such as mechanical properties, electrical properties and chemical and heat resistance. However, as the field of use of polyacetal resins expands, in some cases, special properties are further required for their properties as materials. As one of the above properties, it is desired to have a material having excellent bending properties, namely a material having excellent hinge properties in certain cases.

Especially in recent years, with the necessity of cost reduction by reducing the number of parts, it is desirable to install them at low cost as the necessity of integrating some parts using a hinge increases. Moreover, since there are many factors that lower the hinge characteristic, such as the use of the hinge part at low temperatures and the impossibility of obtaining a desirable hinge form in construction, there is a strong demand for essentially excellent hinge characteristics.

Moreover, in the field of general electrical equipment and building materials, opportunities for using various materials for combining various materials meeting the above objectives are also increasing, and it is necessary to further increase the impact resistance of polyacetal resins.

A method of increasing the hinge property or impact resistance by adding an elastomer such as a thermoplastic polyurethane to a polyacetal resin is known as a method of satisfying the hinge property condition.

In addition, although the hinge property can be increased by the above method, there is a problem that mixing of the elastomeric component causes peeling phenomenon on the surface of the molded product, which tends to greatly damage the appearance of the molded product. Moreover, there is a problem that the thermal stability is reduced, the weld strength and extensibility of the molded article are remarkably low, the fluidity is also reduced, and the freedom of hinge design is reduced, which needs to be improved.

In addition, as the function required for the hinge increases recently, the form becomes more complicated, and the wall becomes thinner for the purpose of cost reduction and weight reduction. In order to increase productivity in injection molding, it is necessary to perform in a mold having a plurality of dies in order to shorten the molding cycle and increase the number of molded products obtained by one injection molding.

Disclosure of the Invention

It is an object of the present invention to provide a polyacetal resin composition and a hinge part made of a polyacetal resin having superior hinge properties than conventional ones without impairing other physical properties.

The inventors of the present invention have continued intensive research to solve the above-mentioned problems as much as possible without sacrificing the inherent characteristics of polyacetal resins and to develop polyacetal materials having excellent hinge properties and maintaining toughness. The present invention has been completed by discovering that the addition of a homogeneous blend of saturated fatty acid bisamide to the core / shell polymer is effective.

That is, the present invention comprises (A) 100 parts by weight of a polyacetal resin and (B) a rubbery polymer core and a glassy polymer shell, and 0.3 to 5 parts by weight of saturated fatty acid bisamide of the general formula (1) per 100 parts by weight of the core / shell polymer ), And a hinge part made of a polyacetal resin obtained by molding the polyacetal resin composition, comprising: 1 to 100 parts by weight of a core / shell polymer previously uniformly blended;

R ₁ -CONH-R ₂ -NHCO-R ₃

Where

R ₁ and R ₃ are the same as or different from each other, and each represent a group selected from the group consisting of aliphatic alkyl, substituted alkyl, aryl, and substituted aryl groups having 10 to 22 carbon atoms,

R ₂ represents a divalent hydrocarbon group having 1 to 12 carbon atoms.

The resin composition of this invention contains the above-mentioned (A) and (B), and (B) contains a core / shell polymer and the above-mentioned saturated fatty acid bisamide. The components (A) and (B) are mixed well. The material is a very suitable material for the hinge resin because it provides excellent hinge properties, impact resistance and fluidity which are difficult to achieve.

As described above, the resin composition of the present invention prepared by uniformly blending the core / shell polymer with a specific lubricant (saturated fatty acid bisamide) and kneading it with a polyacetal resin is excellent in terms of hinge properties and fluidity, and It has an excellent effect of maintaining toughness while retaining the acetal's balanced mechanical properties.

The hinge parts obtained by molding the polyacetal resin composition are used as various hinge parts in automobile, electrical and electronic fields, as building materials and in various commodity fields, more specifically in automotive connectors and connectors for electrical installations, and polyacetal. The resin composition is suitably used for such a use.

1A, 1B, and 1C are schematic diagrams of test pieces used to measure hinge characteristics, respectively showing top, side, and enlarged views of the hinge portion. The other unit of measure is mm.

The structural components of the present invention are described in detail below.

First, the polyacetal resin (A) used in the present invention is a high molecular compound having an oxymethylene group (-CH ₂ O-) as a main structural unit, and a polyoxy having a small amount of other structural units in addition to the oxymethylene group, respectively. It may be one of methylene homopolymers and copolymers, terpolymers and block copolymers, or may have branched or crosslinked structures as well as linear structures. Polyacetal resins having a melt index of 0.2 to 30 g / 10 minutes, more preferably 0.5 to 15 g / 10 minutes, measured according to ASTM D1238-89E at a cylinder temperature of 190 ° C. are used in the present invention.

In the next step, the core / shell polymer (B) used in the present invention comprises 0.3 to 5 parts by weight of a saturated fatty acid bisamide (core / shell) having a rubbery polymer core and a core / shell polymer having a glassy polymer shell. Per 100 parts by weight of polymer) prior to homogeneous blending to obtain:

Formula 1

R ₁ -CONH-R ₂ -NHCO-R ₃

Where

R ₁ and R ₃ are the same as or different from each other, and each represent a group selected from the group consisting of aliphatic alkyl, substituted alkyl, aryl, and substituted aryl groups having 10 to 22 carbon atoms,

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) previously uniformly blended with the saturated fatty acid bisamides used in the present invention is a compound having a rubbery polymer core and a glassy polymer shell. It may also use a product prepared by known methods or commercially available. Representative examples thereof include acryloid KM330 and KM653 manufactured by Rohm & Haas Co., Ltd. and pararoid manufactured by Kureha Kagaku KK. (Paraloid) Stafiloid PO-0143 and PO-0148 manufactured by Takeda Yakuhin Kogyo KK, Kanegafuchi Kagaku Kogyo Co., Ltd., manufactured by Takeda Yakuhin Kogyo KK. Kaneace FM manufactured by Kanegafuchi Kagaku Kogyo KK, and Metablen C-102, E-901, W-800 and S- manufactured by Mitsubishi Reiyon KK. Include 2001. Of these core / shell polymers, core / shell polymers having a rubbery polymer core and glassy polymer shell comprising methyl methacrylate as the main component are preferred, and core / shell polymers with substantially no anion being found are particularly preferred. . In the case of using a core / shell polymer in which anions are found, polyacetal decomposition is likely to be promoted during melting, kneading and injection molding, thereby failing to obtain desired hinge properties. Moreover, in some cases it decomposes so much that melting and kneading are impossible. A core / shell polymer in which an anion is not substantially detected means a core / shell polymer in which an anion is not detected by conventional qualitative testing. For example, 5 g of sample (core / shell polymer) is weighed in 50 ml of Erlenmeyer flask, 20 ml of ion-exchanged water is added, stirring is continued for 3 hours with a magnetic stirrer, and then filtration through 5C filter paper is carried out The obtained filtrate was divided into two portions, and 0.5 ml of 1% aqueous barium chloride solution was added to one portion to observe the presence of turbidity (sulfate ion qualitative test), and 0.1 instead of 1% aqueous barium chloride solution to compare the presence of turbidity. N-nitrate can be determined by the same method as the method of performing the same process except adding an aqueous solution (halogen ion qualitative test) to confirm the presence of anions. Preferably, core / shell polymers free of these anions are suitably used.

Core / shell polymers preferably used in the present invention are obtained by carrying out emulsion polymerization in the presence of a nonionic surfactant and a neutral radical generating polymerization initiator. Such core / shell polymers can be produced by, for example, emulsion polymerization techniques described in Japanese Patent Laid-Open No. 91-14856. This emulsion polymerization can be carried out, for example, in the presence of the following surfactant and polymerization initiator. Nonionic surfactants include ethers such as polyoxyethylene nonylphenyl ether, polyoxyethylene stearyl ether and polyoxyethylene lauryl ether, esters such as polyoxyethylene monostearate, polyoxyethylene sorbitan monolaurate and A wide variety of commonly used nonionic surfactants can be used, including block polymers such as sorbitan ester types, and polyoxyethylene polyoxypropylene block copolymers. The addition amount is appropriately selected according to the particle stabilization capacity of the surfactant. Azo polymerization initiators such as azobisisobutyronitrile, dimethyl 2,2'-azobisisobutyrate and 2,2'-azobis (2-aminopropane) dihydrochloride, cumene hydroperoxide, diisopropylbenzene Hydrogen peroxide-based polymerization initiators such as hydroperoxide and hydrogen peroxide are used alone or in combination of two or more. Thus, when emulsion polymerization is carried out in reaction systems containing no anions and non-persulfates, core / shell polymers containing little or no anions, even if they contain little or no anion, are obtained. Polyacetal resins using the core / shell polymer, which contain little anion, are excellent in terms of hinge properties.

The core / shell polymer used as a precursor in the present invention has a rubbery polymer core and a glassy polymer shell, and is typically a continuous multistage emulsification in which the polymer obtained in the previous step is sequentially coated on the polymer obtained in the previous step in the seed emulsion polymerization method. Obtained by the polymerization method. When the core / shell polymer has an intermediate phase to be described later, the intermediate phase is formed by a multistage emulsion polymerization method in which in some cases the polymer obtained in the next step penetrates the polymer obtained in the previous step.

In particle generation polymerization, it is preferable to add a monomer, surfactant, and water to a reactor, and then add a polymerization initiator to start an emulsion polymerization reaction. One-step polymerization is a reaction to form a rubbery polymer. Monomers constituting the rubbery polymer include, for example, conjugated dienes or alkyl acrylates having 2 to 8 carbon atoms in alkyl groups, or mixtures thereof. These monomers are polymerized to prepare a rubbery polymer having a glass transition temperature of -30 ° C or lower. The conjugated dienes include, for example, butadiene, isoprene and chloroprene. Moreover, alkyl acrylates in which the alkyl group has 2 to 8 carbon atoms include, for example, ethyl acrylate, propyl acrylate, butyl acrylate, cyclohexyl acrylate and 2-ethylhexyl acrylate.

In the first stage of polymerization, monomers copolymerizable with conjugated dienes and alkyl acrylates, for example, aromatic vinyls such as styrene, vinyltoluene, α-methylstyrene, cyanides such as aromatic vinylidene, acrylonitrile and methacrylonitrile Vinyl, vinylidene cyanide, and alkyl methacrylates such as methyl methacrylate and butyl methacrylate can be copolymerized.

When using a small amount of crosslinking monomers and graft monomers when containing no more than 20% by weight based on the total amount of monomers used in the first step, even if it contains or does not contain conjugated dienes in the first step of polymerization A polymer having impact resistance can be obtained. Examples of crosslinking monomers include aromatic divinyl monomers such as divinylbenzene, ethylene glycol diacrylate, ethylene glycol dimethacrylate, butylene glycol diacrylate, hexanediol diacrylate, hexanediol dimethacrylate. , Alkane polyol polys such as oligoethylene glycol diacrylate, oligoethylene glycol dimethacrylate, trimethylolpropane diacrylate, trimethylolpropane dimethacrylate, trimethylolpropane triacrylate and trimethylolpropane trimethacrylate Acrylate or alkane polyolpolymethacrylates. Especially, butylene glycol diacrylate and hexanediol diacrylate are used preferably. Graft monomers include, for example, unsaturated carboxylic allyl esters such as allyl acrylate, allyl methacrylate, diallyl maleate, diallyl fumarate and diallyl itaconate. In particular, allyl methacrylate is used preferably. The crosslinking monomer and graft monomer are used in the range of 0 to 5% by weight, preferably 0.1 to 2% by weight, based on the total amount of monomers used in the first step.

The core of the rubbery polymer is preferably 50 to 90% by weight based on the total amount of the core / shell polymer. When the core is in the range of less or more than the weight range, the resin composition obtained by melting and blending the resultant core / shell polymer does not provide a satisfactory effect of improving impact resistance in certain cases. Moreover, when the core has a high glass transition temperature of -30 ° C or higher, a satisfactory effect of improving impact resistance at low temperatures is not provided in certain cases.

A glassy polymer is formed in the outermost layer (shell phase). The monomers constituting the glassy polymer include a mixture of methyl methacrylate and a monomer copolymerizable with methyl methacrylate and form a glassy polymer having a glass transition temperature of at least 60 ° C. Monomers copolymerizable with methyl methacrylate include, for example, alkyl methacrylates such as ethyl methacrylate and butyl methacrylate, alkyl acrylates such as ethyl acrylate and butyl acrylate, styrene, vinyltoluene and α-methylstyrene Vinyl polymerizable monomers comprising vinyl cyanide and vinylidene cyanide, such as aromatic vinyls such as aromatic vinylidene, aromatic vinylidene, acrylonitrile and methacrylonitrile. In particular, ethyl acrylate, styrene and acrylonitrile are preferably used.

The outermost layer (shell phase) is preferably 10 to 50% by weight, based on the total amount of core / shell polymer. When the shell phase is less or more than the weight percent range, the resin composition obtained by melting and blending the resulting core / shell polymer does not provide a satisfactory effect of improving impact resistance in certain cases.

Furthermore, an intermediate phase may be present between the polymerization phase produced in the first step and the polymerization phase produced in the last step. Intermediate phases include, for example, polymerizable monomers having functional groups such as glycidyl methacrylate, methacrylic acid and hydroxyethyl methacrylate, polymerizable monomers and methyl acrylates which produce free-phase polymers such as methyl methacrylate. Polymerizable monomers that produce the same rubbery polymer are prepared by seed emulsion polymerization. The intermediate phase can be selected from a variety according to the properties of the desired core / shell polymer. The polymerization ratio can be appropriately selected depending on the monomer used. For example, when a glassy polymer is used in the intermediate phase, the polymerization ratio can be calculated as part of the shell, and in the case of rubbery polymer, it can be calculated as core part.

The structure of the core / shell polymer having the intermediate phase includes a multilayer structure in which another layer is present between the core and the shell, and a salami structure in which the intermediate phase is dispersed in the core in the form of fine particles. In core / shell polymers having a salami structure, the intermediate phase to be dispersed sometimes forms a new core in the central portion of the core in extreme cases. In certain cases where a monomer represented by styrene is used as the monomer constituting the intermediate phase, a core / shell polymer having the above structure is produced. In addition, when a core / shell polymer having an intermediate phase is used, the impact resistance is improved in certain cases, the flexural modulus is easily increased, the heat deformation temperature is increased, and the appearance (by surface peeling, suppression of pearlescent gloss, and change of refractive index) Hue change) is easy to improve.

As a method of providing a polyacetal resin having impact resistance, a method of adding a core / shell polymer to a polyacetal resin has been known so far as a method other than adding a rubbery material. This method satisfies conditions other than the hinge properties, but polyacetal resins have inherent inferior hinge properties, so that the addition of the core / shell polymer further reduces the hinge properties. No polyacetal resins have been provided that have satisfactory hinge properties while maintaining flowability and non-peelability properties.

Thus, the addition and blending of conventional core / shell polymers to polyacetal resins increases toughness without degrading the excellent mechanical properties of the polyacetal resins, but has produced very inferior hinge properties, thus using polyacetal resins for hinge parts. It becomes impossible.

Therefore, the present invention is characterized by kneading the component (B) obtained by combining the above-described core / shell polymer component with a specific lubricant (saturated fatty acid bisamide) with the polyacetal resin (A). The combination of the two components (A) and (B) by this method is very effective in improving the hinge properties without compromising the well balanced properties inherent in the polyacetal resin.

The three components of the polyacetal resin, the core / shell polymer and the lubricant may be blended by kneading any two components and then adding the other component to continue mixing and kneading the three components simultaneously. have.

In a method of kneading a polyacetal resin and a core / shell polymer and then adding a lubricant to continue kneading, the effect exerted by the lubricant not only deteriorates the kneading conditions but also worsens the dispersibility of the lubricant, resulting in a polyacetal resin produced. The composition is inferior in uniformity. As a result, the hinge part obtained by molding the polyacetal resin composition thus obtained is inferior in function as a hinge, so this method is not preferable.

Another method is to knead the polyacetal resin and the lubricant and then continue to knead by adding more core / shell polymers. However, since the polyacetal resin containing lubricant is kneaded with the core / shell polymer, the core / shell polymer is difficult to uniformly disperse, and the hinge parts obtained by molding the polyacetal resin composition thus obtained are also inferior in terms of function as a hinge. This method is also undesirable.

Moreover, even if the three components are kneaded simultaneously, the hinge part obtained by molding the polyacetal resin composition thus obtained is inferior in function as a hinge similarly to the above-described method, so this method is also undesirable.

Even if these three components are kneaded in any of the above-described ways, the core / shell polymer and lubricant have poor dispersibility, and the uniformity of the polyacetal resin composition thus obtained is poor. Therefore, the hinge part obtained by molding the polyacetal resin composition thus obtained is inferior in function as a hinge, so this method is not preferable.

However, the inventors of the present invention have found that a method of pre-uniformly blending saturated fatty acid bisamides with core / shell polymers and adding them to polyacetal resins is effective for hinge parts.

In the present invention, the polymer blended into the polyacetal resin is a lubricant-containing core / shell polymer obtained by uniformly blending the entire amount of the lubricant to be blended with the polyacetal resin composition and the core / shell polymer. Saturated fatty acid bisamide, for example, a solution obtained by dissolving saturated fatty acid bisamide in a solvent is mixed with a commercial core / shell polymer by a Henshell mixer, followed by removal of the solvent, or saturated fatty acid bisamide The shell polymer may be uniformly dispersed in advance in the core / shell polymer using the method of addition in the drying step of emulsion polymerization.

The saturated fatty acid bisamides used for this purpose in the present invention are represented by the following general formula (1):

Formula 1

R ₁ -CONH-R ₂ -NHCO-R ₃

Where

R ₁ and R ₃ are the same as or different from each other, and each represent a group selected from the group consisting of aliphatic alkyl, substituted alkyl, aryl, and substituted aryl groups having 10 to 22 carbon atoms,

R ₂ represents a divalent hydrocarbon group having 1 to 12 carbon atoms.

It is obtained from certain alkylenediamines and certain saturated fatty acids.

The saturated fatty acid component of the saturated fatty acid bisamide has 11 to 23 carbon atoms, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, margaric acid, stearic acid, nonadecanoic acid, Arachidic acid and behenic acid. Of these, stearic acid is particularly preferred.

Divalent hydrocarbon groups of saturated fatty acid bisamides preferably include alkylene groups such as monomethylene, dimethylene, trimethylene, tetramethylene, pentamethylene and hexamethylene. Among these, monomethylene and dimethylene are particularly preferable.

Of the aforementioned saturated fatty acid bisamides, ethylenebisstearic acid amide (C ₁₇ H ₃₅ -CONH-CH ₂ -CH ₂ -NHCO-C ₁₇ H ₃₅ ) and methylenebisstearic acid amide (C ₁₇ H ₃₅ -CONH-CH ₂ -NHCO-C ₁₇ H ₃₅ ) is particularly preferred.

The amount of the saturated fatty acid bisamide added is suitably 0.3 to 5 parts by weight, preferably 1 to 5 parts by weight and particularly preferably 2 to 4 parts by weight per 100 parts by weight of the core / shell polymer. An amount less than 0.3 parts by weight reduces the effect of improving the hinge properties, and an amount of 5 parts by weight or more adversely affects the properties inherent to the polyacetal resin due to the improvement effect reaching saturation.

The kneading / mixing of the saturated fatty acid bisamides with the polyacetal resin (A) and the core / shell polymer provides a polyacetal resin composition with excellent toughness but does not provide a molded hinge part with excellent hinge properties. However, exhibiting notable improvements, the effect of providing excellent hinge properties by pre-mixing the core / shell polymer with saturated fatty acid bisamide is found.

In molded articles obtained by adding and blending the core / shell polymer to the polyacetal resin, the core / shell polymer is dispersed in the form of particles on the surface such that when the molded article is bent, the core / shell polymer breaks or breaks at the origin. Therefore, the composition obtained by mix | blending a polyacetal resin (A) and a core / shell polymer is inferior in hinge characteristic. However, by pre-mixing the core / shell polymer with saturated fatty acid bisamides, a marked improvement is exerted, and the effect of providing excellent hinge properties is found.

The effect is that even if the primary particles are agglomerated into a secondary particle mass aggregated to a few tens of microns, even if the primary particles are about several microns, the core / shell polymer is uniform to the primary particles simply by kneading with the polyacetal resin. Although not dispersed, it is thought that the core / shell polymer is preliminarily blended with the saturated fatty acid bisamide when the core / shell polymer is uniformly dispersed into the primary particles when kneaded with the polyacetal resin. The great effect provided by using saturated fatty acid bisamides as lubricants is expected by the fact that the great affinity for the shell components of the core / shell polymers raises the core / shell polymer dispersion capacity. These working effects are not necessarily clear, but the present invention is not limited thereto.

According to the invention, the addition amount of the core / shell polymer (B) combined with the saturated fatty acid bisamide is 1 to 100 parts by weight, preferably 5 to 50 parts by weight, per 100 parts by weight of the polyacetal resin. When the addition amount of the core / shell polymer is too small, the hinge property and impact resistance do not appear satisfactorily, and when the addition amount is too large, the mechanical properties, in particular, the rigidity are greatly reduced, and the effect on the thermal stability is poor.

Moreover, it is desirable to add various known stabilizers to the compositions of the present invention to enhance thermal stability. For this purpose, it is preferred to use known antioxidants, nitrogen-containing compounds and alkali or alkaline earth metal compounds alone or in combination of two or more thereof.

In addition, known additives, for example, lubricants other than saturated fatty acid bisamides, nucleating agents, mold release agents, antistatic agents, other surfactants, organic polymer materials, and inorganics, in order to impart desired properties to the composition of the present invention. Or organic fibrous, particulate or plate fillers or the like can be added to the composition alone or in combination of two or more additives.

The composition of this invention can be manufactured using the method and equipment generally known as a manufacturing method of a synthetic resin composition. That is, the essential components can be blended, kneaded using a single screw or twin screw extruder, and extruded to produce molding pellets, which can then be used for molding. Alternatively, the composition can be prepared simultaneously with molding in a molding machine. In order to improve the dispersion and blending of the respective components, a method of producing pellets by grinding, mixing, melting and extruding some or all of the resin components is advantageous. Any of the above methods are possible.

Materials such as the stabilizers and additives described above can be added at any stage, and it is also possible to add and blend just before obtaining the final molded article.

The resin composition according to the present invention can be molded by any extrusion molding, injection molding, compression molding, vacuum molding, blow molding, or foam molding.

The present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. "Parts" shown in Examples and Comparative Examples refer to parts by weight. Abbreviations used in Examples and Comparative Examples are as follows.

(Where a: b = 7: 3 and a + b = about 13.6)

Preparation of Core / Shell Polymers (B-1) and (B'-1)

To a polymerization vessel equipped with a 5 L reflux condenser, DIW 1200 g, 1.68 g of 25% aqueous ammonia, 7 g of surfactant A, and 0.14 g of MAM were added and heated to 70 ° C. while stirring under a nitrogen stream. 27.86 g of seed monomer mixture having the following composition was added and the mixture was dispersed for 10 minutes. Next, 21 g of a V50 10% aqueous solution was added to polymerize the seed particles.

Seed monomer:

Subsequently, 7 g of MAM was added, and a monomer emulsion obtained by adding and mixing 210 g of surfactant A, 900 g of DIW, and 2.80 g of 25% aqueous ammonia to 1500 g of a core partial monomer mixture having the following composition, and 10% V50 Seed polymerization was carried out by continuously supplying a mixture of 21.0 g of an aqueous solution and 0.63 g of 1% aqueous ammonia for 180 minutes.

Core Part Monomer Mixture:

The temperature was raised to 80 ° C, aged for 1 hour, and then cooled to 70 ° C.

In the next step, 9 g of a V 50 10% aqueous solution and 0.27 g of 1% aqueous ammonia were added, and the shell partial monomer emulsion having the following composition, 12 g of a V50 10% aqueous solution, and 0.36 g of 1% aqueous ammonia were continuously supplied for 60 minutes. Emulsion polymerization was carried out.

Shell Part Monomer Mixture:

It heated up to 80 degreeC, aged for 1 hour, and cooled. The solution was filtered through 300 mesh wire gauze to obtain a core / shell polymer latex.

This latex was frozen to -15 ° C and filtered through a glass filter. Subsequently, foam drying was performed at 60 ° C. for 24 hours to obtain a core / shell polymer (B′-1).

Solution obtained by dissolving 60 g of ethylenebisstearic acid amide (registered trademark: Armowax, manufactured by Lion Akzo Co., Ltd.) in 100 ml of DMF by a Henschel mixer. After mixing the core / shell polymer, the solvent was removed under reduced pressure to obtain the core / shell polymer (B-1).

Preparation of Core / Shell Polymers (B-2 to B-5) and (B'-2 and B-3)

The polymerization was carried out in the same manner as in B-1, except that the monomer having the composition shown in Table 1 was used to obtain the core / shell polymers (B-2 to B-5) and (B'-2 and B'-3). Got.

Preparation of Core / Shell Polymer (B'-4)

The polymerization was carried out in the same manner as in B-1, except that a monomer having the composition shown in Table 1 was used and no lubricant was added, thereby obtaining a core / shell polymer (B′-4).

Sulfate ion qualitative test

Sulfate ions contained in the core / shell polymers (B-1 to B-5) and (B'-1 to B'-4) were detected.

That is, 5 g of the sample was weighed in a 50 ml Erlenmeyer flask, 20 ml of ion-exchanged water was added, and stirred with a magnetic stir bar for 3 hours.

In the next step, the filtrate obtained by filtering the solution through the filter paper No. 5C was divided into two portions, and 0.5 ml of 1% aqueous barium chloride solution was added all at once to observe the formation of turbidity.

In this qualitative test, sulfate ions were not detected from the core / shell polymers (B-1 to B-5) and (B'-1 to B'-4).

Polyacetal:

POM copolymer resin, registered trademark: Duracon, manufactured by Polyplastics.

A-1 melt index (190 ° C.): 2.5 (g / 10 min)

A-2 melt index (190 ° C.): 9.0 (g / 10 min)

Examples 1-8

The POM copolymer resin Duracon manufactured by Polyplastics Co., Ltd. and the core / shell polymers (B-1 to 5) prepared in the same manner as described above in the composition shown in Table 2 were dried to a moisture content of 0.3% or less. Thereafter, using a twin screw extruder PCM-30 manufactured by Ikegai Tekko KK, it was melted and kneaded at a cylinder temperature of 190 ° C and a die head temperature of 200 ° C, and pelletized. This pellet was dried at 80 degreeC for 3 hours or more, it shape | molded using the injection molding machine, the test piece was produced, and the following evaluation was performed. The results are shown in Table 2 below.

Comparative Examples 1 to 11

POM copolymer resin Duracon manufactured by Polyplastics Co., Ltd. and the core / shell polymers (B′-1 to 4) prepared in the same manner as described above in the composition shown in Table 3 were dried to a moisture content of 0.3% or less. After it was made, it was melted and kneaded and pelletized at a cylinder temperature of 190 ° C. and a die head temperature of 200 ° C. using a twin screw extruder PCM-30 manufactured by Ikegai Deco. Using this pellet, a test piece was prepared in the same manner as in the above example, and the following evaluation was performed. The results are shown in Table 3 below.

The characteristic evaluation of an Example and a comparative example was performed according to the following method.

(1) evaluation of hinge characteristics

After the test piece having the form shown in Fig. 1 was molded, it was evaluated according to the criteria shown below.

Number of samples: n = 10

Test Method: The sample was left at −10 ° C. and 50% RH for at least 24 hours, and then the hinge portion was repeatedly bent at 180 degree angles 100 times under the same conditions.

Evaluation A: Number of hinge parts broken during 100 bendings (the smaller the number, the better)

Evaluation B: After bending 100 times, the hinge part state was evaluated according to the following criteria, and the average point was displayed (the larger the value, the better).

5: A little strange thing was hardly observed.

4: A fine crack generate | occur | produced on the surface of the hinge part.

3: The crack generate | occur | produced on the hinge part surface, and it became large.

2: The crack of the hinge part grew toward the center part, and the hinge part became extremely thin.

1: A cutting line was seen in the thin hinge part, and there was almost no cutting | disconnection.

0: It was broken.

(2) Izod impact strength

The resin pellets prepared in Examples and Comparative Examples were molded into test samples (12.7 mm wide, 6.4 mm thick, 64 mm long rectangular parallelepiped) using an inline injection molding machine, and notched according to the method of ASTM D 256 to impact Izod. The value was measured. The larger the Izod value, the better.

Moreover, the shaping | molding method of the test piece used for evaluation of hinge characteristic and mechanical property is shown below:

* Molding machine: IS80 manufactured by Toshiba K.K.

* Molding conditions :

(3) measuring flowability (flow length of thin-walled rods)

Using the molding machine set according to the following conditions, the thin-walled test piece (width 5mm X thickness 0.5mm) was shape | molded, and fluidity | liquidity was evaluated from the flow length (length filled with resin).

* Molding machine: PS20E manufactured by Nissei K.K.

* Molding conditions :

Claims (8)

(A) 100 parts by weight of a polyacetal resin and (B) a rubbery polymer core and a glassy polymer shell, and 0.3 to 5 parts by weight (per 100 parts by weight of the core / shell polymer) of saturated fatty acid bisamides of the following general formula (1) Polyacetal resin composition comprising 1 to 100 parts by weight of the blended core / shell polymer: Formula 1 R ₁ -CONH-R ₂ -NHCO-R ₃ Where R ₁ and R ₃ are the same as or different from each other, and each represent a group selected from the group consisting of aliphatic alkyl, substituted alkyl, aryl, and substituted aryl groups having 10 to 22 carbon atoms, R ₂ represents a divalent hydrocarbon group having 1 to 12 carbon atoms. The method of claim 1, The polyacetal resin composition wherein the core / shell polymer (B) is a polymer in which anions are substantially not detected. The method of claim 1, The polyacetal resin composition wherein the core / shell polymer (B) is obtained by emulsion polymerization using a nonionic surfactant and a polymerization initiator that generates neutral free radicals. The method of claim 1, The polyacetal resin composition whose shell of a core / shell polymer (B) is a polymer containing methyl methacrylate as a main component. The method of claim 1, Saturated fatty acid components of saturated fatty acid bisamides include undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, margaric acid, stearic acid, nonadecanoic acid, arachidic acid and behenic acid. Polyacetal resin composition selected from the group consisting of. The method of claim 1, A polyacetal resin composition wherein the divalent hydrocarbon group of saturated fatty acid bisamide is selected from the group consisting of monomethylene, dimethylene, trimethylene, tetramethylene, pentamethylene and hexamethylene groups. The method of claim 1, Saturated fatty acid bisamides are ethylenebisstearamide (C ₁₇ H ₃₅ -CONH-CH ₂ -CH ₂ -NHCO- C ₁₇ H ₃₅ ) and / or methylenebisstearamide (C ₁₇ H ₃₅ -CONH-CH ₂ -NHCO-C ₁₇ H ₃₅ ). The polyacetal resin hinge part manufactured by shape | molding the polyacetal resin composition of Claim 1.