JP2001089633A - Polyoxymethylene resin composition and molded body prepared therefrom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyoxymethylene resin composition excellent in abrasion and wear resistance to metallic shaft hole and gear durability to the polyoxymethylene resin under the conditions of high load, and molded articles prepared therefrom. SOLUTION: A polyoxymethylene resin composition comprises (A) 100 pts.wt. of a polyoxymethylene resin, (B) 0.5-12 pts.wt. of a polyethylene resin graft- modified with an aromatic vinyl monomer alone or with the aromatic vinyl monomer and an active-hydrogen-containing vinyl monomer, and (C) 0.1-10 pts.wt. of an ester of a dicarboxylic acid and an aliphatic alcohol. The composition is suitable for use in the field of precision apparatus, OA apparatus and automobiles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel polyoxymethylene resin excellent in slidability under severe conditions of high load, and particularly to the durability and durability required for a gear material used near a drive motor. A composition with excellent friction and wear properties with metal bearings and shafts. This material is suitable for precision equipment, OA equipment, sliding parts materials in the field of automobiles, and the like.

[0002]

2. Description of the Related Art Polyoxymethylene resin is widely used as an engineering resin having balanced mechanical properties and excellent wear resistance in various mechanical parts, OA equipment and the like. However, this polyoxymethylene resin is not sufficient as a sliding material only with its inherent abrasion resistance. Therefore, grease is applied to a sliding portion and used. Since the application of grease requires a long working process, a polyoxymethylene resin composition that does not require application of grease is required, and some improvements have been made.

For example, a method of adding a fatty acid ester to a polyoxymethylene resin (JP-B-53-31900), a method of adding an ester of 1,4-butanediol and a fatty acid (JP-B-55-23304), glycerin A method of adding a borate ester of a monofatty acid ester (Japanese Patent Publication No. 57-15616), a method of adding a polyolefin having active hydrogen, polyethylene and isocyanate (Japanese Patent Application Laid-Open No. 4-126758), a method of adding an α-olefin and ethylene- A method of adding a copolymer with a vinyl monomer (JP-A-49-40346) and a method of adding an ultra-high-molecular-weight polyethylene powder (JP-A-60-40346).
1444351), but the improvement effect is not sufficient.

As a technique directly related to the present invention, there is disclosed a method using a polyethylene resin graft-modified with an aromatic vinyl monomer alone or an active hydrogen-containing vinyl monomer used in the present invention, and an ester comprising a fatty acid and a fatty acid alcohol (Japanese Patent Laid-Open Publication No. 8-199039) and a method using an ester of a dicarboxylic acid and an aliphatic alcohol used in the present invention (Japanese Patent Application Laid-Open No. 8-283530). The hole friction and wear properties are not sufficient, and the latter have insufficient gear durability when the mating material is polyoxymethylene.

[0005]

SUMMARY OF THE INVENTION Under such circumstances, the present invention has an excellent friction and wear property with respect to a metal shaft hole under high load conditions, and an excellent gear durability with a polyoxymethylene resin. The purpose was to develop a polyoxymethylene composition.

[0006]

Means for Solving the Problems The present inventors have made intensive studies to achieve the above object, and as a result, a polyoxymethylene resin was graft-modified with an aromatic vinyl monomer alone or with an active hydrogen-containing vinyl monomer. The inventors have found that when a specific amount of a combination of a polyethylene resin and an ester of a dicarboxylic acid and an aliphatic alcohol is used, the present invention has been found to exert remarkable effects.

That is, the present invention provides: (A) 100 parts by weight of a polyoxymethylene resin,
(B) 0.5 to 20 parts by weight of a polyethylene resin graft-modified with an aromatic vinyl monomer alone or an active hydrogen-containing vinyl monomer, and (C) 0.1 to 10 parts by weight of an ester of an aliphatic alcohol and a dicarboxylic acid. 1. A polyoxymethylene resin composition containing: The aromatic vinyl monomer in the polyethylene resin graft-modified with the aromatic vinyl monomer alone or the active hydrogen-containing vinyl monomer as the component (B) is a vinyl monomer containing a benzene ring, and the active hydrogen-containing vinyl monomer is α, β unsaturated. 2. The resin composition according to 1, which is a hydroxyl group-containing ester of a carboxylic acid, acrylic acid, methacrylic acid, acrylamide, allylamine, or allyl alcohol. (C) The resin composition according to any one of (1) to (2), wherein the ester of the aliphatic alcohol and the dicarboxylic acid as the component is a monoester, a diester of a saturated or unsaturated primary alcohol having 8 or more carbon atoms and a dicarboxylic acid, and a mixture thereof. A molded article obtained by molding the composition described in 4.1, 2 and 3, and a gear, a cam obtained by molding and cutting the composition described in 5.1, 2 and 3; 5. mechanical components that are sliders, clutches, rollers, joints, shafts or bearings; The above-mentioned mechanical components such as gears, cams, sliders, clutches, rollers, joints, shafts or bearings are components used in proximity to the drive motor.

Hereinafter, the present invention will be described in detail. The polyoxymethylene resin used in the component (A) of the present invention is obtained by polymerizing cyclic oligomers such as formaldehyde or its trimer, trioxane or tetramer, and terminating both ends of the polymer with ether or ester groups. Including formaldehyde or its trimer trioxane or tetramer tetraoxane, and ethylene oxide, propylene oxide, 1,3-dioxolan, formal of glycol,
Oxymethylene copolymers containing 0.1 to 20% by weight of oxyalkylene units having 2 to 8 carbon atoms obtained by copolymerizing diglycol with formal or the like, and those further having a branched molecular chain, from oxymethylene units At least one oxymethylene block polymer containing 50% by weight or more and 50% by weight or less of different segments.

The melting index MI (measured under the conditions of ASTM-D1238-57T) of the polyoxymethylene resin used in the present invention is from 0.1 g / 10 min to 50 g / 10 min, preferably from 0.5 g / 10 min to 30 g / 10 min. It is. 0.
If it is less than 1 g / 10 minutes, extrusion molding is difficult, and 50 g /
If the time exceeds 10 minutes, the durability is insufficient. Further, as the polyoxymethylene resin used in the present invention, it is preferable to use a homopolymer having a high flexural modulus or a polyoxymethylene copolymer in which the amount of a comonomer is reduced. In the polyoxymethylene resin of the present invention, stabilizers used in conventional polyoxymethylene resins, for example, heat stabilizers and weather (light) stabilizers can be used alone or in combination. Antioxidants, formaldehyde and formic acid scavengers and their combination are effective as heat stabilizers

As the antioxidant, a hindered phenol-based antioxidant is preferable, for example, n-octadecyl-3- (3'5'-di-t-butyl-4'-hydroxyphenyl) -propionate, n-octane. Octadecyl-3-
(3'-methyl-5'-t-butyl-4'-hydroxyphenyl) -propionate, n-tetradecyl-3-
(3'5'-di-t-butyl-4'-hydroxyphenyl) -propionate, 1,6-hexanediol-bis- (3- (3,5-di-t-butyl-4-hydroxyphenyl)- Propionate), 1,4-butanediol-bis- (3- (3,5-di-t-butyl-4-hydroxyphenyl) -propionate), triethylene glycol-bis- (3- (3-t-butyl) -5-methyl-4-hydroxyphenyl) -propionate),

[0011] Tetrakis- (methylene-3- (3 ',
5'-di-t-butyl-4'-hydroxyphenyl) propionate methane, 3,9-bis (2- (3- (3-
t-butyl-4-hydroxy-5-methylphenyl) propionyloxy) -1,1-dimethylethyl) 2
4,8,10-tetraoxaspiro (5,5) undecane, N, N′-bis-3- (3′5′-di-tert-butyl-4-hydroxyphenol) propionylhexamethylenediamine, N , N'-tetramethylenebis-3-
(3'-methyl-5'-t-butyl-4-hydroxyphenol) propionyldiamine, N, N'-bis-
(3- (3,5-di-t-butyl-4-hydroxyphenol) propionyl) hydrazine, N-salicyloyl-N'-salicylidenehydrazine, 3- (N-salicyloyl) amino-1,2,4- Triazole, N, N'-
Bis (2- (3- (3,5-di-butyl-4-hydroxyphenyl) propionyloxy) ethyl) oxyamide;

Among these hindered phenolic antioxidants, triethylene glycol-bis- (3- (3
-T-butyl-5-methyl-4-hydroxyphenyl)
-Propionate), tetrakis- (methylene-3-
(3 ', 5'-Di-t-butyl-4'-hydroxyphenyl) propionate methane is preferred, and triethylene glycol-bis- (3- (3-t-butyl-5-methyl-4-hydroxyphenyl) is preferred. ) -Propionate) is particularly preferred.

Examples of the formaldehyde and formic acid scavengers include (a) a compound or polymer containing formaldehyde-reactive nitrogen, (b) a hydroxide, inorganic acid salt, carboxylate or alkoxide of an alkali metal or alkaline earth metal. And the like. Examples of the compound containing (a) formaldehyde-reactive nitrogen include (1) dicyandiamide, (2) amino-substituted triazine, and (3) co-condensate of amino-substituted triazine with formaldehyde. (2) Examples of the amino-substituted triazine include guanamine (2,4-diamino-sym-triazine), melamine (2,4,6-triamino-sym-triazine), N-butylmelamine,
N-phenylmelamine, N, N-diphenylmelamine,
N, N-diallylmelamine, N, N ', N "-triphenylmelamine, N-methylolmelamine, N, N'-
Dimethylolmelamine, N, N ′, N ″ -trimethylolmelamine, benzoguanamine (2,4-diamino-
6-phenyl-sym-triazine),

2,4-diamino-6-methyl-sym-
Triazine, 2,4-diamino-6-butyl-sym-
Triazine, 2,4-diamino-6-benzyloxy-
sym-triazine, 2,4-diamino-6-butoxy-sym-triazine, 2,4-diamino-6-cyclohexyl-sym-triazine, 2,4-diamino-6
-Chloro-sym-triazine, 2,4-diamino-6
-Mercapto-sym-triazine, 2,4-dioxy-6-amino-sym-triazine (Amelite), 2
-Oxy-4,6-diamino-sym-triazine (ameline), N, N ', N'-tetracyanoethylbenzoguanamine and the like.

(3) Examples of cocondensates of amino-substituted triazines and formaldehyde include melamine-formaldehyde polycondensates. Of these, dicyandiamide, melamine and melamine-formaldehyde polycondensates are preferred.

Further, (a) the polymer containing a formaldehyde-reactive nitrogen group includes (1) a polyamide resin,
(2) a polymer obtained by polymerizing acrylamide and its derivative or acrylamide and its derivative with another vinyl monomer in the presence of a metal alcoholate; (3) acrylamide and its derivative or acrylamide and its derivative and other vinyl monomer And (4) amines, amides,
Polymers containing a nitrogen group such as urea and urethane may be used.

As the polyamide resin (1), nylon 4-6, nylon 6, nylon 6-6 and nylon 6-1 are used.
0, nylon 6-12, nylon 12 and the like and copolymers thereof, for example, nylon 6 / 6-6, nylon 6/6
-6 / 6-10, nylon 6 / 6-12 and the like. (2) Examples of the polymer obtained by polymerizing acrylamide and its derivative or acrylamide and its derivative and another vinyl monomer in the presence of a metal alcoholate include a poly-β-alanine copolymer. These polymers are described in JP-B-6-12259 and JP-B-5-87.
No. 096, JP-B 5-47568 and JP-A-3-23.
It can be produced by the method described in each publication of No. 4729. (3) Polymers obtained by polymerizing acrylamide and its derivatives or acrylamide and its derivatives and other vinyl monomers in the presence of radical polymerization are disclosed in
It can be produced by the method described in Japanese Patent Application No. -28260.

(B) Examples of the alkali metal or alkaline earth metal hydroxide, inorganic acid salt, carboxylate or alkoxide include hydroxides such as sodium, potassium, magnesium, calcium and barium;
Examples of the metal include carbonate, phosphate, silicate, borate and carboxylate. The carboxylic acid of the carboxylate is, for example, a saturated or unsaturated aliphatic carboxylic acid having 10 to 36 carbon atoms, and these carboxylic acids may be substituted with a hydroxyl group. As the saturated aliphatic carboxylic acids, capric acid, lauric acid, myristic acid,
Palmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid, serotinic acid, montanic acid, melissic acid, and celloplastic acid. Examples of the unsaturated aliphatic carboxylic acid include undecylenic acid, oleic acid, elaidic acid, setleic acid, erucic acid, brassic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid, propiolic acid, and stearic acid. Examples of the alkoxide include methoxide and ethoxide of the above metals.

As the weather (light) stabilizer, (a) benzotriazole-based substances, (b) oxalic anilide-based substances and (c) hindered amine-based substances are preferred. (A) As the benzotriazole-based substance, for example, 2- (2′-
(Hydroxy-5'-methyl-phenyl) benzotriazole, 2- [2'-hydroxy-3,5-di-t-butyl-phenyl) benzotriazole, 2- [2'-hydroxy-3,5-di-isoamyl -Phenyl) benzotriazole, 2- [2'-hydroxy-3,5-bis-
(Α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (2′-hydroxy-4′-octoxyphenyl) benzotriazole and the like, preferably 2- [2′-hydroxy-3, 5-bis-
(Α, α-dimethylbenzyl) phenyl] -2H-benzotriazole and 2- [2′-hydroxy-3,5-di-t-butyl-phenyl) benzotriazole.

(B) As the oxalic acid anilide-based substance,
For example, 2-ethoxy-2'-ethyloxalic acid bisanilide, 2-ethoxy-5-t-butyl-
2'-ethyloxalic acid bisanilide, 2-
Ethoxy-3'-dodecyloxalic acid bisanilide and the like. Each of these substances may be used alone or in combination of two or more.

(C) As the hindered amine-based substance,
4-acetoxy-2,2,6,6-tetramethylpiperidine, 4-stearoyloxy-2,2,6,6-tetramethylpiperidine, 4-acryloyloxy-2,
2,6,6-tetramethylpiperidine, 4- (phenylacetoxy) -2,2,6,6-tetramethylpiperidine 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, 4-methoxy-2 , 2,6,6-tetramethylpiperidine, 4-stearyloxy-2,26,
6-tetramethylpiperidine, 4-cyclohexyloxy-2,2,6,6-tetramethylpiperidine, 4-benzyloxy-2,2,6,6-tetramethylpiperidine, 4-phenoxy-2,2,6, 6-tetramethylpiperidine, 4- (ethylcarbamoyloxy) -2,
2,6,6-tetramethylpiperidine, 4- (cyclohexylcarbamoyloxy) -2,2,6,6-tetramethylpiperidine, 4- (phenylcarbamoyloxy) -2,2,6,6-tetramethylpiperidine,

Bis (2,2,6,6-tetramethyl-4
-Piperidine) -carbonate, bis (2,2,6,6)
-Tetramethyl-4-piperidyl) -oxalate, bis (2,2,6,6-tetramethyl-4-piperidyl)
-Malonate, bis (2,2,6,6-tetramethyl-
4-piperidyl) -sebacate, bis (2,2,6,6)
-Tetramethyl-4-piperidyl) -adipate, bis (2,2,6,6-tetramethyl-4-piperidyl)-
Terephthalate, 1,2-bis (2,2,6,6-tetramethyl-4-piperidyloxy) -ethane, α, α ′
-Bis (2,2,6,6-tetramethyl-4-piperidyloxy) -p-xylene, bis (2,2,6,6-tetramethyl-4-piperidyl) tolylene-2,4-dicarbamate, Bis (2,2,6,6-tetramethyl-4
-Piperidyl) -hexamethylene-1,6-dicarbamate, tris (2,2,6,6-tetramethyl-4-piperidyl) -benzene-1,3,5-tricarboxylate, tris (2,2, 6,6-tetramethyl-4-piperidyl) -benzene-1,3,4-tricarboxylate and the like, and preferably bis (2,2,6,6-
Tetramethyl-4-piperidyl) -sebacate.

The above hindered amine-based substances may be used alone or in combination of two or more. The combination of the above-mentioned benzotriazole-based substance and / or oxalic anilide-based substance and a hindered amine-based substance is most preferable. In the polyethylene resin graft-modified with the aromatic vinyl monomer alone or the active hydrogen-containing vinyl monomer used in the component (B) of the present invention, the aromatic vinyl monomer is a vinyl monomer containing a benzene ring. For example, alkyl-substituted styrenes such as styrene, methyl styrene and ethyl styrene are preferable, and among them, styrene is preferable.

The active hydrogen-containing vinyl monomer is, specifically, 2-hydroxyethyl methacrylate or 2-hydroxyethyl methacrylate.
Hydroxypropyl methacrylate, 2-hydroxyethyl acrylate, hydroxypropyl acrylate,
Hydroxyl-containing esters of α, β unsaturated carboxylic acids such as 2-hydroxybutyl methacrylate, p-hydroxyphenyl methacrylate, p-hydroxybenzyl methacrylate, glycerin monomethacrylate, polyethylene glycol methacrylate, polypropylene glycol methacrylate, acrylic acid, methacrylic acid, Acrylamide, allylamine, allyl alcohol and the like. Of these, hydroxyl group-containing esters of α, β unsaturated carboxylic acids are preferred, and 2-hydroxyethyl methacrylate is particularly preferred.

The polyethylene constituting the graft-modified product is a polyethylene comprising 90% by weight or more of ethylene units and 10% by weight or less of vinyl monomer units such as butene-1 and propylene. Preferred molecular weight is 2,000-
In the range of 1,000,000 and specific gravity of 0.91
Those having a melting point in the range of 100 to 140 ° C. and a melting point of 100 to 140 ° C. are preferred. Specific examples are polyethylene wax,
Examples thereof include low-density polyethylene, linear low-density polyethylene, high-density polyethylene, and ultrahigh-molecular-weight polyethylene, and low-density polyethylene, which is a homopolymer of ethylene having a number average molecular weight of 20,000 to 50,000, is preferred.

The method for producing the polyethylene graft-modified with the aromatic vinyl monomer alone or with the active hydrogen-containing vinyl monomer in the present invention includes a method in which the vinyl monomer is grafted onto the polyethylene in the presence of a radical initiator and a method in which the vinyl monomer is prepared in advance. There is a method of manufacturing by a method of grafting a polymer. Preferably “Polymer Paper Collection”
Vol. 44, No. 2, pp. 89-95 (1987), which is a method of producing a polymer having a peroxide chain in a side chain using a grafting reaction to polyolefin.

The content of the aromatic vinyl monomer in the graft-modified product of the present invention is from 20 to 20
It is preferable to contain 40% by weight. More preferably 25 to
35% by weight. The amount of the active hydrogen-containing vinyl monomer based on the total amount of the graft is in the range of 0.1 to 3% by weight, preferably 0.3 to 2.5% by weight.
Among the graft-modified products in the present invention, preferred are a styrene graft polymer on polyethylene and a graft polymer of a hydroxyl group-containing ester copolymer of styrene-α, β unsaturated carboxylic acid on polyethylene.

The amount of the polyethylene graft-modified with the aromatic vinyl monomer alone or the active hydrogen-containing vinyl monomer in the present invention is in the range of 0.5 to 12 parts by weight per 100 parts by weight of the polyoxymethylene resin. If the amount is less than 0.5% by weight, the effect of improving the friction and wear properties is insufficient. If the amount exceeds 12% by weight, the molded product may be peeled off. The preferred addition amount is 1 to 10 parts by weight, more preferably 2 to 7 parts by weight, based on 100 parts by weight of the polyoxymethylene resin.

The aliphatic alcohol in the ester of the aliphatic alcohol and the dicarboxylic acid used for the component (C) of the present invention is specifically octyl alcohol, nonyl alcohol, decyl alcohol, undecyl alcohol,
Lauryl alcohol, tridecyl alcohol, myristyl alcohol, bentadecyl alcohol, cetyl alcohol, heptadecyl alcohol, stearyl alcohol, oleyl alcohol, nonadecyl alcohol, eicosyl alcohol, seryl alcohol, behenyl alcohol, melisyl alcohol, hexyldecyl alcohol, octyldodecyl It is a saturated or unsaturated primary alcohol having 8 or more carbon atoms, such as alcohol, decyl myristyl alcohol, decyl stearyl alcohol, and uniline alcohol.

The dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanoic acid, brassic acid, maleic acid, fumaric acid, It is a dicarboxylic acid such as glutaconic acid. Esters of these aliphatic alcohols and dicarboxylic acids are monoesters, diesters and mixtures thereof, and may contain unreacted aliphatic alcohols. Among these esters of alcohol and dicarboxylic acid, esters of saturated aliphatic alcohol having 10 or more carbon atoms and dicarboxylic acid are preferable.

The amount of the ester of the aliphatic alcohol and the dicarboxylic acid in the present invention ranges from 0.1 to 10 parts by weight based on 100 parts by weight of the polyoxymethylene resin. The effect of improving abrasion is insufficient, and if it exceeds 10% by weight, bleeding is observed on the surface of the molded product, which is not preferable. The preferred amount is 0.3 to 8 parts by weight, more preferably 0.5 to 6 parts by weight, based on 100 parts by weight of the polyoxymethylene resin.

Further, the polyoxymethylene resin composition of the present invention may be, if desired, various additives (for example, polyolefin-based resins and the like) conventionally used in polyoxymethylene resins as long as the object of the present invention is not impaired. Resins, lubricants, release agents, inorganic fillers, dyes and pigments other than those described in the present application) can be used. In the method for producing the composition of the present invention, a generally used melt kneader can be used. Examples of the melt kneader include a kneader, a roll mill, a single-screw extruder, a twin-screw extruder, and a multi-screw extruder.
The processing temperature at this time is preferably 180 to 240 ° C., and in order to maintain the quality and the working environment, it is preferable to replace with an inert gas or to perform deaeration with single-stage and multi-stage vents.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples. The contents of components used in Examples and Comparative Examples and evaluation methods are shown below. [Contents of Ingredients Used] Polyoxymethylene resin A-1; a polyoxymethylene homopolymer having a melt index of 9 g / 10 min (ASTM D-1238-57 (E condition)) having both terminals acetylated and a flexural modulus of 30,000 kg / cm ² A- 2, a melt index of 9 g / 10 min (AST) containing 0.6% by weight of 1,3 dioxolane as a copolymer component
Flexural modulus of 3 under MD-1238-57T (E condition)
Melt index 9 g / 10 min (AST) containing 3.6% by weight of polyoxymethylene copolymer A-3; 1,3 dioxolane of 000 kg / cm ^2.
The flexural modulus is 2 under MD-1238-57T (E condition).
6,000 kg / cm ² polyoxymethylene copolymer

B. Polyethylene graft-modified with an aromatic vinyl monomer alone or with an active hydrogen-containing vinyl monomer ("Polymer's Journal", Vol. 44, No. 2, 89
B-1; low density polyethylene having Mn = 30,000; B-1; a graft polymer produced using a method utilizing a grafting reaction of a polymer having a peroxide bond to polyolefin described in p. 95 (1987). And a polystyrene (30% by weight) graft polymer.

B-2: Graft polymer of low-density polyethylene having Mn = 30,000, styrene (28% by weight) and 2-hydroxyethyl methacrylate (2% by weight) copolymer. B-3; Low density polyethylene with Mn = 30,000

C. Ester of dicarboxylic acid and aliphatic alcohol C-1; dilauryl adipate (0.5% by weight)
C-2; dimyristyl adipate (containing 0.3% by weight of monoester) C-3; distearyl adipate (containing 0.3% by weight of monoester) C-4; myristine Acid cetyl ester C-5; stearyl stearate

D. Stabilizer D-1; triethylene glycol-bis- [3- (3-
t-butyl-5-methyl-4-hydroxyphenyl) propionate] D-2; poly-β-alanine D-3; polyamide 66 D-4; calcium stearate

[Evaluation method] (1) Evaluation of physical properties Melt flow rate; ASTM D-1238-57
Measured based on T. Tensile strength, elongation; measured based on ASTM D638. Flexural strength, modulus of elasticity; measured according to ASTM D790. Izod impact strength; measured based on ASTM D256. (2) Repeated Impact Strength A test piece adjusted to measure Izod impact strength was subjected to a load of 160 with a repeated impact tester manufactured by Toyo Seiki Co., Ltd.
g, a drop height of 20 mm, and a drop speed of 35 times / minute, a repeated impact test was performed, and the number of times until breakage was measured.

(3) Sliding performance of shaft hole The pellets obtained in Examples and Comparative Examples were dried at 80 ° C. for 3 hours, and thereafter, a 1-ounce molding machine (Toyo Machine Metal Co., Ltd.) set at a cylinder temperature of 200 ° C. 6 mmφ × under the conditions of mold temperature 70 ° C. and cooling time 20 seconds by TI-30G).
A pulley with a gear having a shaft hole of 17 mm was formed.
This pulley was set on a SUS shaft, and a resin small bearing friction and wear tester (Shinko Zoki Co., Ltd.) was used.
Intermittent operation at a load of 4 kg and a rotation speed of 600 rpm (15 sec.
cON / 1 secOFF), the friction coefficient after 1,000,000 rotations and the wear amount (maximum wear depth) of the SUS shaft were measured, and the wear discoloration of the SUS shaft was evaluated based on the following criteria. The test was performed at 23 ° C. and 50% humidity.

The SUS shaft was ranked according to the following criteria by visual observation. ○: almost no discoloration △: thin linear discoloration ×: discoloration blackened over the entire contact surface XX; degree of discoloration is greater than × (4) Gear durability test A 1 oz. Injection molding machine set at a cylinder temperature of 200 ° C was used. Using a mold having a mold temperature of 80 ° C. and a pitch circle diameter of 3
0mm, module 1.0mm, number of teeth 30, pressure angle 20
A gear having a tooth width of 5 mm was formed. Using a gear durability tester, set a gear of the same shape made of Tenac-C4520 on the drive side, combine the formed gear on the driven side and rotate at a load torque of 5 kg-cm at 318 rpm until the gear breaks until the gear breaks. The rotation speed was measured. (5) Surface Peeling Test of Molded Product The surface peeling of a test piece for a tensile test was examined.

[0041]

Example 1 Polyoxymethylene resin 10 of component A-1
0 parts by weight, 3 parts by weight of a graft polymer of low-density polyethylene of Mn = 30000 of component B-1 and styrene (30% by weight), 2 parts by weight of dilauryl adipate of component C-1 and D as a stabilizer -1 component triethylene glycol-bis- [3- (3-t-butyl-5-methyl-
4-Hydroxyphenyl) propionate] and 0.3 part by weight of poly-2D-component poly-β-alanine were uniformly blended with a Henschel mixer, and then L / D = 30 set at 200 ° C. Extrusion kneading was performed using a twin screw extruder. The extruded resin was formed into pellets with a strand cutter, and evaluation was performed using the obtained pellets. Table 1 shows the results.

[0042]

Examples 2 to 4 The procedure of Example 1 was repeated except that the amount of the component B was changed to the amount shown in Table 1. Table 1 shows the results.

[0043]

Comparative Examples 1 and 2 The same procedure as in Example 1 was carried out except that the amount of the component B was changed to the amount shown in Table 1. Table 1 shows the results.

[0044]

Comparative Example 3 The same operation as in Example 1 was carried out except that the component B was not added. Table 1 shows the results.

[0045]

Examples 5 to 7 The same procedure as in Example 1 was carried out except that the amount of the component C was changed to the amount shown in Table 1. Table 1 shows the results.

[0046]

Comparative Examples 4 and 5 The same procedure as in Example 1 was carried out except that the amount of the component C was changed to the amount shown in Table 1. Table 1 shows the results.

[0047]

Comparative Example 6 The same operation as in Example 1 was carried out except that the component C was not added. Table 1 shows the results.

[0048]

Example 8 Polyoxymethylene resin 10 of component A-2
0 parts by weight, 3 parts by weight of a graft polymer of a low-density polyethylene of Mn = 30000, styrene (28% by weight) and 2-hydroxyethyl methacrylate (2% by weight) copolymer of component B-2, component C-1 2 parts by weight of adipic acid dilauryl ester, and triethylene glycol-bis- [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] of component D-1 as a stabilizer.
3 parts by weight and 0.3 part by weight of poly-β-alanine of the D-2 component were uniformly blended with a Henschel mixer.
Extrusion kneading was performed using a twin screw extruder with L / D = 30 set at 0 ° C. The extruded resin was formed into pellets with a strand cutter, and evaluation was performed using the obtained pellets. Table 2 shows the results.

[0049]

Examples 9 and 10 The same procedure as in Example 8 was carried out except that the component C was changed to those shown in Table 2. Table 2 shows the results.

[0050]

Comparative Example 7 The same operation as in Example 1 was carried out except that the component B was changed to the one shown in Table 2. Table 2 shows the results.

[0051]

Comparative Examples 8 and 9 The same procedure as in Example 1 was carried out except that the amount of the component C was changed to that shown in Table 2. Table 2 shows the results
Shown in

[0052]

Example 11 Polyoxymethylene resin 1 of component A-2
00 parts by weight, 3 parts by weight of a graft polymer of low-density polyethylene of Mn = 30000 of component B-1 and styrene (30% by weight), 2 parts by weight of dilauryl adipate of component C-1 and D as a stabilizer 0.3 parts by weight of triethylene glycol-bis- [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] -1 component and 0.1 parts by weight of polyamide 66 of component D-3 And 0.05 parts by weight of calcium stearate were uniformly blended with a Henschel mixer, and then L
Extrusion kneading was performed using a twin screw extruder with / D = 30. The extruded resin was formed into pellets with a strand cutter, and evaluation was performed using the obtained pellets. Table 2 shows the results.
Shown in

[0053]

Example 12 The same operation as in Example 11 was carried out except that the component C was changed to that shown in Table 2. Table 2 shows the results.

[0054]

Examples 13 and 14 The same procedure as in Examples 11 and 12 was carried out except that the component A was changed to the polyoxymethylene resin of A-3. Table 2 shows the results.

[0055]

[Table 1]

[Table 2]

According to the present invention, a polyoxymethylene resin is combined with an aromatic vinyl monomer alone or a polyethylene resin graft-modified with an active hydrogen-containing vinyl monomer and an ester of an aliphatic alcohol with a dicarboxylic acid, Under high load conditions, which has been considered difficult in the past, the abrasion resistance against the shaft hole in the metal is excellent, and the durability of the gear with the polyoxymethylene resin can be improved.

Claims (6)

[Claims] (A) 100 parts by weight of a polyoxymethylene resin; (B) 0.5 to 12 parts by weight of a polyethylene resin graft-modified with an aromatic vinyl monomer alone or with an active hydrogen-containing vinyl monomer; A polyoxymethylene resin composition containing 0.1 to 10 parts by weight of an ester of an acid and an aliphatic alcohol. (2) The aromatic vinyl monomer in the polyethylene resin graft-modified with the aromatic vinyl monomer alone or the active hydrogen-containing vinyl monomer as the component (B) is a vinyl monomer containing a benzene ring, and the active hydrogen-containing vinyl monomer is The resin composition according to claim 1, which is a hydroxyl group-containing ester of an α, β unsaturated carboxylic acid, acrylic acid, methacrylic acid, acrylamide, allylamine, or allyl alcohol. 3. The ester of an aliphatic alcohol and a dicarboxylic acid as the component (C) is a monoester, a diester of a saturated or unsaturated primary alcohol having 8 or more carbon atoms and a dicarboxylic acid, and a mixture thereof. The resin composition according to any one of claims 1 and 2. 4. A molded article obtained by molding the polyoxymethylene composition according to claim 1, 2 or 3. 5. A mechanical component which is a gear, cam, slider, clutch, roller, joint, shaft or bearing obtained by molding and cutting the composition according to claim 1, 2 or 3. 6. The mechanical component, which is a gear, cam, slider, clutch, roller, joint, shaft or bearing obtained by molding and cutting, is a component used in proximity to a drive motor. Mechanical parts.