JPH039945A - Polyacetal resin composition - Google Patents

Abstract

PURPOSE:To improve a notched Izod impact strength by incorporating a glycidyl (meth)acrylate-modified product of an acid-modified olefin polymer in a polyacetal resin at a specified ratio. CONSTITUTION:An acid-modified olefin polymer (a) obtd. by modifying an olefin polymer (i) (e.g. ethylene-ethyl acrylate copolymer) with 0.1-30 pts.wt. (hereinbelow described as pts.) unsatd. carboxylic acid (a driv. thereof) (ii) (e.g. maleic anhydride) based on 100 pts. component (i) is modified with 0.05-30 pts. glycidyl (meth)acrylate (b) based on 100 pts. component (a) to obtain a glycidyl (meth)acrylate-modified product of the acid-modified olefin polymer. 1-30 pts. said product is incorporated in 100 pts. polyacetal resin having a melt flow rate (ASTMD-1238, 190 deg.C) of 0.1-50g/10min and contg. 80mol% or more oxymethylene units in the main chain.

Description

[Detailed description of the invention] [Industrial application field] The present invention has excellent heat resistance, rigidity, bending strength, impact resistance, etc.
This invention relates to a polyacetal resin composition that has no drawbacks such as delamination and has excellent moldability.

[Conventional technology] Polyacetal resin has excellent heat resistance, mechanical properties,
It has creep properties, lubricating properties, and electrical properties, and is widely used in automobile parts, electronic/electrical equipment parts, audio equipment parts, water supply equipment parts, toy parts, etc.

However, although polyacetal resin has low temperature dependence of mechanical properties and can be used under a wide range of temperature conditions, its disadvantages include low notched impact strength, residual stress during molding, and microscopic There are drawbacks such as the possibility of damage if there are scratches, such as gears, bolts, etc.
It is not suitable for molding mechanical parts such as nuts or molded products with complex shapes, and it is necessary to improve its impact resistance.

Conventionally, methods for improving the impact resistance of polyacetal resins include adding ionomers (Japanese Patent Publication No. 45-18023), ethylene-ethyl acrylate copolymer (Japanese Patent Publication No. 45-2623), etc. to polyacetal resins. It has been proposed to add it, but it causes delamination and
Mechanical strength was insufficient, particularly notched isot impact strength.

[Problems to be Solved by the Invention] In view of the above circumstances, the present inventors have developed a method for mechanical parts such as gears, bolts, nuts, etc. made of polyacetal resin, which are not easily damaged by impact, and which have particularly excellent notched isot impact strength. The objective of the present invention is to provide a polyacetal resin composition.

[Means for solving the problem] The present inventors previously disclosed in Japanese Patent Application No. 150118/1983,
A method for obtaining a glycidyl (meth)acrylate modified product of an acid-modified olefin polymer is proposed, and the above-mentioned problem of notched isot impact strength can be improved by adding the modified product to a polyacetal resin. They discovered this and completed the present invention.

That is, the present invention is a polyacetal resin composition characterized in that 1 to 30 parts by weight of a glycidyl (meth)acrylate modified product of an acid-modified olefin polymer is added to 100 parts by weight of the polyacetal resin. be. The olefinic polymers used in the present invention are ethylene, propylene, butene-1,4-methylpentene-1
, hexene-1, octene-1, nonene-1, decene-1
1. It means a homopolymer of α-olefin such as dodecene-1 or a mutual copolymer thereof, or a copolymer of ethylene and vinyl ester, unsaturated carboxylic acid, unsaturated carboxylic acid ester, etc.

Examples of the olefin polymer of the present invention include high-pressure polyethylene, medium-low pressure polyethylene, and vapor-phase ethylene-α
-Olefin copolymer, LLDPE, polypropylene,
Polybutene, ethylene-vinyl acetate copolymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-butyl acrylate copolymer,
These include ethylene-propylene copolymer, ethylene-propylene-diene terpolymer, and the like.

The acid-modified olefin polymer used in the present invention refers to the above-mentioned olefin polymers such as acrylic acid, methacrylic acid, methyl methacrylic acid, maleic acid,
It is modified with fumaric acid, itaconic acid, citraconic acid, hemic acid, maleic anhydride, citraconic anhydride, crotonic acid, isocrotonic acid, etc.

Modification methods include dissolving the olefinic polymer and the unsaturated carboxylic acid or its derivative in an organic solvent, adding an organic peroxide and heating, and heating and kneading the olefinic polymer and the unsaturated carboxylic acid or its derivative. It can be obtained by a method such as adding an unsaturated carboxylic acid or its derivative to an olefinic polymer and then irradiating it with an electron beam or ultraviolet rays, but the method is not particularly limited. An acid-modified olefin polymer obtained by copolymerizing a derivative can also be used.

In the present invention, the acid component content of the acid-modified olefin polymer is preferably 0.1 to 30 parts by weight per 100 parts by weight of the olefin polymer; if it is less than 0.1 part by weight, the impact resistance will not be improved. It is not sufficient, and more than 30 parts by weight does not increase the effect.

The acid-modified olefin polymer modified with glycidyl (meth)acrylate used in the present invention is one obtained by modifying the acid-modified olefin polymer of the present invention described above with glycidyl acrylate or glycidyl (meth)acrylate.

Good results can also be obtained by modification with other glycidyl group-containing vinyl monomers, such as epoxy stearyl (meth)acrylate, vinyl glycidyl ether, allyl glycidyl ether, etc. In the present invention, the component ratio of glycidyl (meth)acrylate is 0.05 to 30 parts by weight based on 100 parts by weight of the acid-modified olefin polymer. If it is less than 0.05 parts by weight, it will not help improve the impact strength, and if it is more than 30 parts by weight, the effect will not increase.

In the present invention, the method of modifying the acid-modified olefin polymer with glycidyl (meth)acrylate is to heat and knead both together with an organic peroxide, or to dissolve both in an organic solvent and then add the organic peroxide and heat. The method is not particularly limited.

The heating temperature is 10°C above the melting point of the olefin polymer.
The melting temperature is preferably from 100°C to 350°C. However, in the case of polymers that do not have a melting point above room temperature, the temperature is preferably from 100°C to 350°C.

The polyacetal resin used in the present invention is a homopolymer of formaldehyde, trioxane, tetraoxane, etc., or a copolymer of two or more thereof, or a combination of the monomer and a cyclic ether, cyclic ester, or vinyl compound. copolymers and others. Here, cyclic ethers include ethylene oxide, propylene oxide, and others, and cyclic esters include β-propiolactone, γ
-butyrolactone, etc.

The polyacetal resin used in the present invention usually contains 80 mol% or more of oxymethylene units in its main chain, and has a melt flow rate (MFR) (190°C) of 0 as measured by ASTM D-1238. .1-5
0 g/10 m1n is desirable.

The homopolymer is produced, for example, by introducing substantially anhydrous formaldehyde into an organic solvent containing a basic polymerization catalyst such as an organic amine, polymerizing it, and then acetylating the ends with acetic anhydride. In addition, the copolymer can be prepared by dissolving or suspending substantially anhydrous trioxane and copolymer components such as ethylene oxide or 1,3-dioxolane in an organic solvent such as cyclohexane, and then forming a solution of diethyl boron trifluoride. It is produced by polymerizing by adding a Lewis acid catalyst such as etherate, and decomposing and removing unstable terminals with a basic compound. Alternatively, it is produced by introducing hetrioxane, copolymerization components, and catalyst into a self-cleaning stirrer without using any solvent, performing bulk polymerization, and then adding a basic substance to decompose and remove unstable terminals. do.

The amount of glycidyl (meth)acrylate modified acid-modified olefin polymer used in the present invention is 1 to 30 parts by weight based on 8100 parts by weight of the polyacetal resin alone.
Parts by weight are preferred. If it is less than 1 part by weight, the effect of improving impact resistance is small, and if it exceeds 30 parts by weight, heat resistance and rigidity may decrease.

In the present invention, the polyacetal resin and the glycidyl (meth)acrylate modified acid-modified olefin polymer are mixed using a conventionally known method.

For example, a single screw extruder, a twin screw extruder, a roll, a Banbury mixer, a kneader, a Henschel mixer, etc. are used.

The obtained polyacetal resin composition is molded by conventionally known methods such as injection molding, extrusion molding, foam molding, rotational molding, compression molding, etc.
Used for electronic parts, automobile parts, piping, building materials, industrial parts, miscellaneous goods, precision machinery parts, etc. Especially the gear
Suitable for mechanical parts such as bolts and nuts, and molded products with complex shapes that require excellent notched impact strength.

Commonly used additives for resins may be added to the polyacetal resin composition of the present invention. For example, antioxidants, lubricants, various organic and inorganic pigments, ultraviolet inhibitors, dispersants, neutralizing agents, nucleating agents, crosslinking agents, flow improvers, dyes, carbon black, flame retardants, asbestos, glass fibers. , titanate whiskers, talc, silica, calcium carbonate, pumice, silica alumina, kaolin, mica, etc. may be added to the extent that they do not impair the physical properties of the molded article made from the polyacetal resin composition of the present invention.

(Example) Example 1 and Comparative Examples 1 to 4 0.5 parts of maleic anhydride per 100 parts of ethylene-ethyl acrylate copolymer pellets (hereinafter referred to as EEA) having a melt index of 4 and an ethyl acrylate content of 25% by weight. ,
t-Butylperoxyisopropyl carbonate 0.0
5 parts of antioxidant (2,6-di-t-butyl-p-cresol) and 0.1 part of antioxidant (2,6-di-t-butyl-p-cresol) were mixed in a Henschel mixer at 60°C for 10 minutes.
It was extruded at 70°C and pelletized (hereinafter referred to as AEEA).
.

In addition, per 100 parts of EEA, 5 parts of glycidyl methacrylate, an antioxidant [tetrakis(methylene(3,5-
210.1 parts of di-t-butyl-4-hydroxyhydrocinnamate)) were mixed in a Henschel mixer at 60°C for 10 minutes, then left to stand day and night, then extruded at 170°C in a twin-screw extruder to form pellets. (hereinafter referred to as GEEA)
).

Next, to 100 parts of AEEA, 5 parts of glycidyl methacrylate, an antioxidant [tetrakis(methylene (3,5
-di-t-butyl-4-hydroxyhydrocinnamate)) 210.1 parts of meta was added at 60°C in a Henschel mixer.
After being mixed for 10 minutes in
A).

5 parts by weight of each of the above pellets were added to 100 parts by weight of a polyacetal resin "Delrin 100" manufactured by DuPont having a VFR of 2.3 g/10 m1n, and mixed for 20 minutes using a Henschel mixer.

This mixture was extruded and pelletized using a 40 mm twin screw extruder with a cylinder temperature of 190°C.

After that, the cylinder temperature was set to 230°C and the injection pressure was set to 1 ton/ton.
cm'' and a mold temperature of 90'C, and the MFR and Izod impact test (ASTMD-256; notched) were measured. The measurement results are shown in Table 1.

Example I GAEEA O,918,5 Comparative Example 1
- 2.0 10.5 Comparative Example 2 EEA
1.3 12.0 Comparative Example 3 AEEA
1.2 13.4 Comparative Example 4 GEEA 1
．． 2 14.2 Example 2 and Comparative Examples 5 to 6 In the same manner as in Example 1, instead of EEA, a low-pressure process low-density polyethylene (ethylene-butene copolymer) with a melt index of 4 and a density of 0.935 was used. acrylic acid modified PEB (hereinafter referred to as APEB) and glycidyl methacrylate modified product of APEB (hereinafter referred to as G
APEB) pellets were obtained and their physical properties were measured. The results are shown in Table 2.

Clothing--2 Example 2 GAPEB 1.0 17.3 Comparative Example 5 FEB 1.4 11.4 Comparative Example 6
APEB 1.2 12.7 (Effect of the invention) The polyacetal resin composition of the present invention contains glycidyl (
Because it contains a meth)acrylate-modified acid-modified olefin polymer, it has extremely high notched iso-impact strength, especially mechanical parts such as gears, bolts, and nuts, and molded products with complex shapes that require impact resistance. It is widely applied to fields where

Claims (2)

[Claims] (1) A polyacetal resin composition characterized in that 1 to 30 parts by weight of a glycidyl (meth)acrylate modified product of an acid-modified olefin polymer is blended with 100 parts by weight of the polyacetal resin. (2) The polyacetal resin composition according to claim 1, wherein the acid-modified olefin polymer is a maleic anhydride-modified ethylene-ethyl acrylate copolymer.