JPH0791440B2 - Polyoxymethylene composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polyoxymethylene composition having excellent heat resistance stability, oil resistance, hydrolysis resistance, base resistance, and mechanical properties.

[Conventional technology]

Polyoxymethylene is known as an engineering plastic having a high degree of crystallinity and excellent mechanical properties.
However, due to its chemical structure, it is extremely susceptible to oxidative deterioration, and various compounding formulations of heat stabilizers have been studied conventionally.

For example, a technique for improving heat resistance stability by adding and mixing a phenolic antioxidant, an alkaline earth metal salt and a tertiary aliphatic amine to polyoxymethylene is disclosed in Japanese Patent Publication No.
46-35980.

Further, a composition obtained by blending polyoxymethylene with polyvinyl alcohol or a saponified product of ethylene / vinyl acetate copolymer for the purpose of improving the heat resistance stability of polyoxymethylene is disclosed in JP-A-62-288648, 62- It is disclosed in Japanese Patent No. 288649.

[Problems to be Solved by the Invention]

However, in the method disclosed in Japanese Patent Publication No. 46-35980, since an aliphatic amine having a relatively low molecular weight is used, it volatilizes in the molten state or the amine itself is decomposed, resulting in polyoxygenation. The improvement in heat resistance stability of methylene was insufficient.

Further, as disclosed in JP-A Nos. 62-288648 and 62-288649, the addition of a saponified product of polyvinyl alcohol or an ethylene / vinyl acetate copolymer does not improve the heat stability of polyoxymethylene. It was very low.

[Means for Solving the Problems]

The present inventors have found the present invention as a result of intensive studies to solve the above problems.

That is, in the present invention, formaldehyde and / or a cyclic oligomer of formaldehyde and another cyclic ether are polymerized in the presence of a Lewis acid catalyst under substantially anhydrous and solvent-free conditions and then represented by the general formula (A). To 100 parts by weight of polyoxymethylene obtained by adding a hindered amine compound and stopping the polymerization reaction In the formula, R ¹ represents a hydrogen atom or a monovalent organic residue having 1 to 30 carbon atoms. R ^{2 to} R ⁵ represent an alkyl group having 1 to ⁵ carbon atoms, and may be the same or different. n
Represents an integer of 1 or more, and R ⁶ represents an n-valent organic residue. ) (A) Hindered phenol having a molecular weight of 300 or more 0.001 to 5
(B) At least one selected from alkali metal hydroxides, alkaline earth metal hydroxides, carboxylic acid alkali metal salts, and carboxylic acid alkaline earth metal salts.
5 parts by weight (c) Completely saponified ethylene / vinyl acetate copolymer,
It is a polyoxymethylene composition containing 0.001 to 5 parts by weight of at least one selected from a partially saponified product, a completely saponified product of polyvinyl acetate, and a partially saponified product.

The hindered phenol used in the present invention is a compound having a phenol structure having an alkyl group having 1 to 6 carbon atoms on at least one side of a hydroxyl group, and has a molecular weight of
It is more than 300. Specifically, 2,2'-methylenebis (4-methyl-6-t-butylphenol), triethyleneglycolbis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], penta Erythrityl-tetrakis [3- (3,5-di-t-
Butyl-4-hydroxyphenyl) propionate],
2,2-thiodiethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], N, N '
-Hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl) -4-hydroxybenzyl) benzene, 1,6-hexanediol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,4-bis (n-octylthio) -6 -(4-Hydroxy-3,5-di-t-butylanilino) -1,3,5-triazine, octadecyl-3-
(3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2,2'-thiobis (4-methyl-6-t
-Butylphenol), 3,5-di-t-butyl-4-hydroxybenzylphosphonate-diethyl ester, 1,
3,5-Tris (4-t-butyl-3-hydroxy-2,6-
Dimethylbenzyl) isocyanuric acid, 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 1,1-bis (2-methyl-4-hydroxy-5-t-butyl) Phenyl) butane, N, N'-bis [3
-(3,5-di-t-butyl-4-hydroxyphenyl)
Propionyl] hydrazine, 3,9-bis {2- [3-
(3-t-Butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1-dimethylethyl}-
2,4,8,10-tetraoxaspiro [5.5] undecane and the like can be mentioned. Among them, 2,2'-methylenebis (4-methyl-6-t-butylphenol), triethyleneglycol-bis- [3- ( 3-t-butyl-5-methyl-4
-Hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5-di-t-butyl-4]
-Hydroxyphenyl) propionate], pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-
4-Hydroxyphenyl) propionate], N, N'-
Hexamethylene bis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), 1,3,5-trimethyl-
2,4,6-Tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, 3,9-bis {2- [3- (3-t
-Butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1-dimethylethyl} -2,4,8,10
-Tetraoxaspiro [5.5] undecane is preferred.

If the molecular weight is less than 300, the bleeding phenomenon is observed, the appearance of the molded article is impaired, and the heat stability is lowered, which is not preferable.

Also, the amount added is based on 100 parts by weight of polyoxymethylene.
The amount is 0.001 to 5 parts by weight, preferably 0.01 to 3 parts by weight, and more preferably 0.1 to 2 parts by weight. If it is less than 0.001 part by weight, the heat resistance stability of polyoxymethylene is not sufficient, and if it is more than 5 parts by weight, the bleeding phenomenon is observed or mechanical properties are deteriorated.

Examples of the alkali metal hydroxide used in the present invention include lithium hydroxide, sodium hydroxide and potassium hydroxide, but sodium hydroxide and potassium hydroxide are preferable.

Examples of the hydroxide of alkaline earth metal used in the present invention include magnesium hydroxide, calcium hydroxide, strontium hydroxide and barium hydroxide, and magnesium hydroxide, calcium hydroxide and strontium hydroxide are preferable.

The alkali metal salt of carboxylic acid used in the present invention includes sodium acetate, sodium adipate, sodium laurate, sodium stearate, sodium ricinoleate, potassium ricinoleate, sodium lactate,
Sodium montanate, potassium montanate, sodium behenate, potassium behenate, sodium benzoate,
Examples thereof include potassium benzoate, sodium terephthalate, potassium terephthalate, sodium cinnamate, potassium cinnamate, sodium propionate and sodium butyrate, with sodium stearate and potassium montanate being preferred.

Examples of the alkaline earth metal salt of carboxylic acid used in the present invention include magnesium acetate, calcium acetate, magnesium adipate, calcium adipate,
Magnesium laurate, calcium laurate, magnesium stearate, calcium stearate, strontium stearate, barium stearate, magnesium ricinoleate, calcium ricinoleate, barium ricinoleate, magnesium palmitate, calcium palmitate, magnesium lactate, calcium lactate, montanic acid Magnesium, calcium montanate,
Barium montanate, magnesium behenate, calcium behenate, barium behenate, magnesium benzoate, calcium benzoate, barium benzoate, magnesium terephthalate, calcium terephthalate, magnesium cinnamate, calcium cinnamate, magnesium propionate, propionate Examples include calcium, magnesium butyrate, calcium butyrate, calcium stearate, magnesium stearate, barium stearate, calcium ricinoleate, magnesium palmitate, calcium palmitate, calcium montanate,
Preference is given to magnesium montanate, calcium behenate, magnesium behenate, calcium stearate / calcium palmitate mixtures, magnesium stearate / magnesium palmitate mixtures.

The above-mentioned alkali metal hydroxide, alkaline earth metal hydroxide, carboxylic acid alkali metal salt, and carboxylic acid alkaline earth metal salt may be anhydrous salts or may contain crystallization water.

The addition amount is 0.0 with respect to 100 parts by weight of polyoxymethylene.
The amount is 01 to 5 parts by weight, preferably 0.01 to 3 parts by weight, and more preferably 0.1 to 2 parts by weight. If it is less than 0.001 part by weight, the heat resistance stability of polyoxymethylene is not sufficient, and if it exceeds 5 parts by weight, mechanical properties are deteriorated or heat resistance stability is deteriorated.

The completely saponified product or partially saponified product of an ethylene / vinyl acetate copolymer used in the present invention is a copolymer of ethylene and vinyl acetate saponified by an alcoholysis reaction or the like, and has a general formula (B ) And (C).

In addition, those chemically modified as represented by the general formulas (D) and (E) may be used.

The completely saponified product (polyvinyl alcohol) and partially saponified product of polyvinyl acetate used in the present invention means the polymers represented by the general formulas (F) and (G).

Further, those chemically modified as in the general formulas (H) and (I) may be used.

The addition amount is 0.001 to 100 parts by weight of polyoxymethylene
It is 5 parts by weight, preferably 0.01 to 3 parts by weight, and more preferably 0.1 to 2 parts by weight. If it is less than 0.001 part by weight, the heat resistance stability of polyoxymethylene is not sufficient, and if it exceeds 5 parts by weight, mechanical properties are deteriorated.

The polyoxymethylene used in the present invention is mainly composed of oxymethylene units and contains 15% by weight of oxyalkylene units having 2 to 8 adjacent carbon atoms in the main chain.
It means an oxymethylene copolymer contained below.

The oxymethylene copolymer is, for example, a substantially anhydrous cyclic oligomer of formaldehyde such as trioxane or tetraoxane and a copolymerization component such as ethylene oxide, 1,3-dioxolane or 1,3-dioxepane and an organic solvent such as cyclohexane. After dissolving or suspending in the solution, a Lewis acid catalyst such as boron trifluoride / diethyl etherate is added and polymerized, and unstable terminals are decomposed and removed. Or into a self-cleaning stirrer without using any solvent, cyclic oligomers of formaldehyde such as trioxane or tetraoxane,
After the copolymerization component and the catalyst are introduced and bulk polymerization is carried out, the unstable terminal is further decomposed and removed.

The polyoxymethylene used in the present invention is obtained by polymerizing formaldehyde and / or a cyclic oligomer of formaldehyde and another cyclic ether under substantially anhydrous and solvent-free conditions in the presence of a Lewis acid catalyst. It is a polymer obtained by adding a hindered amine compound represented by (A) to stop the polymerization reaction.

(In the formula, R ¹ represents a hydrogen atom or a monovalent organic residue having 1 to 30 carbon atoms. R ^{2 to} R ⁵ each represent an alkyl group having 1 to ⁵ carbon atoms, which may be the same or different. It may be.
n represents an integer of 1 or more, and R ⁶ represents an n-valent organic residue. ) Specifically, the following compounds may be mentioned.

Among these, 1,2,2,6,6, -pentamethylpiperidine (Z-2), bis (2,2,6,6-tetramethyl-4)
-Piperidinyl) sebacate (G-1), bis (1,2,2,
6,6-Pentamethyl-4-piperidinyl) sebacate (G-2), 1,2,3,4-butanetetracarboxylic acid tetrakis (2,2,6,6-tetramethyl-4-piperidinyl) ester (T- 1), poly {[6- (1,1,3,3-tetramethylenebutyl) amino-1,3,5-triazine-2,4-diyl] [(2,2,6,6-tetramethyl- 4-piperidinyl)
Imino])} (U-1) is preferred.

The hindered amine compound may be added as it is, but may be added as a solution of an organic solvent in order to promote contact with the polymerization catalyst. Organic agents at that time include aromatic hydrocarbons such as benzene, toluene, and xylene,
Aliphatic hydrocarbons such as n-hexane, n-heptane and cyclohexane, alcohols such as methanol and ethanol, halogenated hydrocarbons such as chloroform and 1,2-dichloroethane, and ketones such as acetone and methyl ethyl ketone. To be

The hindered amine compound is preferably added in an amount such that a hindered amine structure is present in an equimolar amount or more to the polymerization catalyst used. Although the catalyst deactivating effect can be seen even when the number of moles of the hindered amine structure is less than the number of moles of the polymerization catalyst used, the heat stability of the obtained polymer is slightly lowered, so depending on the degree of heat stability of interest. It is necessary to adjust the addition amount.

The composition of the present invention includes known colorants (pigments, dyes), conductive agents such as carbon black, flame retardants, glass fibers, carbon fibers, ceramic fibers, aramid fibers, glass beads, reinforcing agents such as glass powder, silica. , A filler such as clay, a nucleating agent such as talc, a lubricant or a release agent such as ethylene bisstearamide, a plasticizer, an adhesive, a heat-sealing agent, an antistatic agent and the like can be optionally contained. In particular, it is preferable to add a nitrogen-containing compound capable of reacting with formaldehyde and capturing formaldehyde as a methylol group because the heat resistance stability is further improved.

Examples of such a nitrogen compound include an amide compound, a urethane compound, a pyridine derivative, a pyrrolidone derivative, a urea derivative, a triazine derivative, a hydrazine derivative and an amidine compound, and specifically, N, N-dimethylformamide, N, N. -Dimethylacetamide, N, N-diphenylformamide, N, N-diphenylacetamide, N, N-diphenylbenzamide, N, N, N ', N'-tetramethyladipamide, oxalic acid dianilide, adipic dianilide, N -Homopolymers or copolymers of lactams such as phenylacetanilide, nylon 6, nylon 11 and nylon 12, dicarboxylic acids such as adipic acid, sebacic acid, decanedicarboxylic acid, dimer acid and ethylenediamine, tetramethylenediamine, hexa Methylenediamine and metaxylylenediamine Homopolymers or copolymers of polyamides derived from diamines, polyamide copolymers derived from lactams and dicarboxylic acids and diamines, polyacrylamides, polymethacrylamides, N, N-bis (hydroxymethyl) sveramides, Amide compounds such as poly (γ-methylglutamate), poly (γ-ethylglutamate), poly (N-vinyllactam), poly (N-vinylpyrrolidone), diisocyanates such as toluene diisocyanate and diphenylmethane diisocyanate, and 1,4-butane Polyurethanes derived from glycols such as diols and polymeric glycols such as poly (tetramethylene oxide) glycol, polybutylene adipate, polycaprolactone, melamine, benzoguanamine, acetoguanamine,
N-butyl melamine, N-phenyl melamine, N, N'-
Diphenylmelamine, N, N ', N "-triphenylmelamine, N-methylolmelamine, N, N'-dimethylolmelamine, N, N', N" -trimethylolmelamine, 2,4-cyamino-6-benzyl Triazine derivatives such as oxytriazine, 2,4-diamino-6-butoxytriazine, 2,4-diamino-6-cyclohexyltriazine, melem and melam, N-phenylurea, N, N'-diphenylurea, thiourea, N -Phenylthiourea, N, N'-diphenylthiourea, ethylene urea, urea derivatives such as nonamethylene polyurea, phenylhydrazine, diphenylhydrazine, benzaldehyde hydrazone, benzaldehyde semicarbazone, benzaldehyde 1-methyl-1-phenylhydrazone, Benzaldehyde thiosemicarbazone, 4- (dialkyla Mino) hydrazine derivatives such as hydrazone of benzaldehyde, dicyandiamide, guanzidine, guanidine, aminoguanidine, guanine, guanacrine, guanoclor, guanoxane, guanosine, amiloride, N-amidino-3-
Amidine compounds such as amino-6-chloropyrancarboxamide, poly (2-vinylpyridine), poly (2-
Methyl-5-vinylpyridine), poly (2-ethyl-5)
-Vinylpyridine), 2-vinylpyridine / 2-methyl-
Examples thereof include pyridine derivatives such as 5-vinylpyridine copolymer and 2-vinylpyridine / styrene copolymer.

The addition amount is 0.001 to 100 parts by weight of polyoxymethylene
It is 5 parts by weight, preferably 0.01 to 3 parts by weight, and more preferably 0.1 to 2 parts by weight. When it is less than 0.001 part by weight, the heat resistance stability of polyoxymethylene is not sufficient, and when it is more than 5 parts by weight, mechanical properties are deteriorated and bleeding phenomenon is observed.

〔Example〕

 Hereinafter, the present invention will be described with reference to examples.

The mechanical properties, MI, polymer melting point, crystallization temperature, oil resistance, and melting torque decrease rate of the molded products shown in Examples and Comparative Examples were measured as follows.

Mechanical properties of molded products 1/8 inc using an injection molding machine with an injection capacity of 5 oz.
A tensile test piece of h thickness x 1/2 inch width and an Izod impact test piece of 1/2 inch thickness x 1/2 inch width were injection molded. Tensile properties were measured according to ASTM D638 and Izod impact values with V notches were measured according to ASTM D256 using these test pieces.

MI (melt index) The pellets dried in a hot air circulation oven at 80 ° C for 3 hours were measured according to ASTM D1238 at a temperature of 190 ° C and a load of 2,160 g.

Polymer melting point (Tm), crystallization temperature (Tc) Using the differential scanning calorimeter of the DuPont thermal analyzer 1090/1091, the polymer melting point was measured by raising the temperature at a heating rate of 10 ° C / min. The crystallization temperature was measured by lowering the temperature at a cooling rate of ° C / min.

Oil resistance Tensile test pieces were immersed in ASTM No. 3 oil heated to 100 ° C., and after 10 days, 20 days and 30 days, they were taken out and subjected to a tensile test.

Melting torque decrease rate 90 g of pellets were put into a Labo Plastomill 100cc mixer manufactured by Toyo Seiki, and melt reduction was performed at 220 ° C / 60 rpm to measure the torque decrease rate. The greater the rate of decrease, the more thermally unstable. This test is a measure of recyclability.

Reference Example 1 Production of polyoxymethylene Production of polyoxymethylene POM-1 Sufficiently dried paraformaldehyde was pyrolyzed at 150 ° C, and the generated formaldehyde gas was introduced into cyclohexanol to produce hemiformal of cyclohexanol. The reaction mixture was distilled to separate hemiformal from the bottom of the column, which was pyrolyzed at 160 ° C. to obtain pure formaldehyde gas.

The formaldehyde gas was introduced at a rate of 100 parts / h into 600 parts of cyclohexane containing 1 × 10 ⁻⁴ mol./tetrabutylammonium propionate. During this period, the reaction temperature was maintained at 30 ° C., and a slurry containing a polymer was appropriately extracted continuously.

Also, a reaction solvent suitable for the extracted slurry (cyclohexane containing tetrabutylammonium propionate)
Was continuously fed.

The extracted slurry was passed through to separate the polymer and washed with acetone, water, and acetone in this order. After drying at room temperature, it was put into 10 times the amount of the polymer in acetic anhydride, and acetic anhydride of 0.
5% at 139 ° C by adding sodium acetate equivalent to 1% by weight
The mixture was heated and stirred for hours. After cooling the reaction mixture to room temperature, the precipitated polymer was separated. After washing with water, acetone and water in this order, it was dried with hot air at 120 ° C. The melting point of this polymer was 175 ° C, the crystallization temperature was 151 ° C, and the MI was 15.6.

Production of polyoxymethylene POM-2 The following raw materials were continuously supplied to a biaxial kneader (30 mmφ, L / D = 10.2) having 26 convex lens type paddles per axis to carry out polymerization.

The polymerization temperature is about 80 by passing warm water through the outer jacket.
The temperature was controlled to ℃ and the rotation speed was set to 175 rpm. The acetal as a molecular weight regulator was dissolved in trioxane, and the boron trifluoride / diethyl etherate as a polymerization catalyst was dissolved in benzene and supplied to the kneader. Further, a premixing zone (mixing in a pipe) was provided at 30 ° C./retention time of 2 minutes so that the 1,3-dioxolane and the catalyst solution were premixed immediately before being supplied to the kneader. The polymer powder thus obtained was put into a 5% aqueous ammonia solution and stirred. The polymer powder was separated, washed with water, acetone and water in this order, then put into a 15% aqueous ammonia solution, and heated and stirred at 150 ° C. for 4 hours in an autoclave. After cooling to room temperature, the precipitated polymer was separated and washed with water, acetone, and water in this order. Further, it was dried in a hot air circulation oven at 80 ° C. for 3 hours. The melting point of this polymer was 169 ° C, the crystallization temperature was 147 ° C, and the MI = 9.0 ° C.

Production of polyoxymethylene POM-3 0.27 parts by weight of bis (1,2,2,6,6−) was polymerized in the same manner as POM-2 and 100 parts by weight of a white powdery polymer discharged from a kneader. A solution of pentamethyl-4-piperidinyl) sebacate (“Sanol LS765” manufactured by Ciba-Geigy) dissolved in 2 parts by weight of benzene was added, and the mixture was stirred and mixed in a Henschel mixer for 10 minutes to deactivate the catalyst. further
It dried for 3 hours in the hot air circulation oven set to 80 degreeC.

The melting point of this polymer is 168 ° C, crystallization temperature is 145 ° C, MI = 8.7.
It was.

Examples 1 to 11, Comparative Examples 1 to 12 Polyoxymethylene POM-1 to POM-3 produced in Reference Example
Various additives were added at the compounding ratio shown in Table 1 to
Melted and kneaded by a twin-screw extruder with a φ, L / D = 31.5 vent. The kneading temperature is set to 220-240 ℃, and the decompression degree is 40-50mm.
Hg. Table 2 shows the results of measuring the physical properties of the obtained composition.

Comparative Examples 13 to 30 Polyoxymethylene POM-1 to POM-3 produced in Reference Example
Various additives were added in the mixing ratio shown in Table 3 to
Melted and kneaded by a twin-screw extruder with a φ, L / D = 31.5 vent. The kneading temperature is set to 220-240 ℃, and the decompression degree is 40-50mm.
Hg. Table 4 shows the results of measuring the physical properties of the obtained composition.

The abbreviations or trade names of additives shown in Tables 1 and 3 represent the following compounds.

Ir1010: Irganox 1010 manufactured by Ciba-Geigy Antioxidant pentaerythrityl-tetrakis [3-
(3,5-di-t-butyl-4-hydroxyphenyl) propionate] Ir245: Irganox 245 manufactured by Ciba-Geigy Antioxidant triethylene glycol-bis [3- (3
-T-butyl-5-methyl-4-hydroxyphenyl)
Propionate] Ir259: Irganox 259 manufactured by Ciba-Geigy Antioxidant 1,6-hexanediol-bis [3- (3,5
-Di-t-butyl-4-hydroxyphenyl) propionate] GA-80: Sumilizer GA-80 Sumitomo Chemical Antioxidant 3,9-bis {2- [3- (3-t-butyl-4-hydroxy- 5-Methylphenyl) propionyloxy] -1,1-dimethylethyl} -2,4,8,10-tetraoxaspiro [5,5] undecane Eval EP-E105: Kuraray ethylene / vinyl alcohol copolymer, melting point 164 ℃, MI = 5.5 Dumilan D-229: Takeda Yakuhin ethylene / vinyl acetate copolymer partially saponified, melting point 95 ℃, MI = 72 Dumilan C-1550: Takeda Yakuhin ethylene / vinyl acetate copolymer partially saponified Modified product Melting point 73 ° C., MI = 15.0 From Examples 1 to 8, resin composition in which hindered phenol, alkali metal or alkaline earth metal salt, and saponified product of polyvinyl acetate-based polymer are mixed with polyoxymethylene. It can be seen that excellent heat stability and oil resistance. It is also found that the heat resistance stability and the oil resistance are excellent regardless of the kind of hindered phenol, the kind of alkali metal or alkaline earth metal salt, and the kind of saponified product of polyvinyl acetate polymer.

From Examples 8 to 11, it is understood that the melt torque stability is improved by further adding and blending the nitrogen-containing compound (formaldehyde scavenger).

From Examples 1 to 11, it can be seen that a particularly stable resin composition can be obtained by using the polymer POM-3 obtained by deactivating the catalyst with the hindered amine compound as the base polymer.

From Comparative Examples 13, 19, and 25, it is understood that not only the hindered phenol is not added, but the initial physical properties are extremely deteriorated and the oil resistance is extremely low.

From Comparative Examples 14, 20, and 26, it is understood that the melting torque stability and the oil resistance are reduced unless alkali metal or alkaline earth metal salts are added.

From Comparative Examples 15, 21, and 27, it is understood that the melting torque stability and the oil resistance are reduced unless the saponified product of the polyvinyl acetate polymer is added.

From Comparative Examples 16, 22, and 28, it can be seen that the initial physical properties and oil resistance deteriorate when multiple additions of hindered phenol are made. Bleed phenomenon was also observed.

From Comparative Examples 17, 23 and 29, it can be seen that when a large amount of alkali metal or alkaline earth metal salt is added, the initial Izod impact value, melting torque stability and oil resistance are lowered.

From Comparative Examples 18, 24 and 30, it can be seen that the initial tensile strength and oil resistance are lowered when a large amount of saponified polyvinyl acetate polymer is added.

[Effects of the Invention] The resin composition of the present invention has excellent mechanical properties, thermal stability, and oil resistance, and therefore can be used in a wide range of applications such as automobile parts and machine mechanism parts.

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area C08L 31:04)

Claims (1)

[Claims] 1. Formaldehyde and / or a cyclic oligomer of formaldehyde and another cyclic ether are polymerized in the presence of a Lewis acid catalyst under substantially anhydrous and solvent-free conditions, and then represented by the general formula (A). To 100 parts by weight of polyoxymethylene obtained by adding a hindered amine compound and stopping the polymerization reaction In the formula, R ¹ represents a hydrogen atom or a monovalent organic residue having 1 to 30 carbon atoms. R ^{2 to} R ⁵ represent an alkyl group having 1 to ⁵ carbon atoms, and may be the same or different. n
Represents an integer of 1 or more, and R ⁶ represents an n-valent organic residue. ) (A) Hindered phenol having a molecular weight of 300 or more 0.001 to 5
(B) At least one selected from alkali metal hydroxides, alkaline earth metal hydroxides, carboxylic acid alkali metal salts, and carboxylic acid alkaline earth metal salts.
5 parts by weight (c) Completely saponified ethylene / vinyl acetate copolymer,
A polyoxymethylene composition comprising 0.001 to 5 parts by weight of at least one selected from a partially saponified product, a completely saponified product of polyvinyl acetate, and a partially saponified product.