JPH05503724A - polyacetal composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] polyacetal composition This invention relates to blends of polyacetals and polymeric impact modifiers. Also , the present invention relates to molded articles formed from such blends.

Polyacetal (also known as polyoxymethylene) has particularly good heat resistance It has physical and mechanical properties, and in particular, the mechanical properties hardly change within a wide temperature range.

Therefore, the potential applications for polyacetals are wide-ranging. However, they It has the disadvantage of low impact strength. Polyacetal is molded into machine parts The low impact strength of the articles makes them particularly It is weakened by surface defects.

Various impact modifiers have been proposed for polyacetals. For example, English National Patent No. 1202454 specifies polyacetal and α-olefin and α, Copolymers of β-unsaturated carboxylic acids whose carboxyl groups are metal ions, preferably at least partially neutralized with sodium ions). There is.

However, as explained in the introduction to British Patent No. 4,556,690, However, this impact modifier is not fully effective. U.S. Patent No. 4,556,690 The specification itself refers to α-olefin polymers and unsaturated carboxylic acids or derivatives thereof. Impact resistance modification containing a modified α-olefin polymer that is a graft copolymer of the body The agent is listed.

The present inventors have discovered α-olefin monomers, polar unsaturated ester monomers, and polyester monomers. Impact modifiers containing monomers that give impact modifiers the ability to interact with acetals. It is surprising that impact modifiers are particularly effective in improving the impact strength of polyacetals. I found out that

The present invention comprises a polyacetal and (i) an α-olefin of 2 to 5 carbon atoms, (i i) polar unsaturated ester monomer and (ifi) terpolymer and polyacetal Neutralization imparts to the neutralized terpolymer the ability to generate ion-dipole interactions between Fully neutralized or partially neutralized tags derived from monomers containing possible monomers -Providing blends of polymers.

The formation of ion-dipole interactions depends on the ion concentration in the terpolymer being sufficiently high. provide sufficient adhesion between the polyacetal and the impact modifier, provided that Strong enough to ensure uniform dispersion.

Polyacetals that can be used in the present invention include formaldehyde, trioxane or is a homopolymer of tetraoxane, a copolymer of two or more of these monomers, or one or more of these monomers and one or more cyclic ethers, cyclic esters, if It is a copolymer of vinyl compounds.

Examples of cyclic ethers that can be used are ethylene oxide, propylene oxide, Ogisacyclobutene, styrene oxide, 3゜3-nooxalate and shrimp Contains lorohydrin.

Examples of cyclic esters include β-propiolactone. An example of a vinyl compound is isobutylene Tyrene, styrene, vinyl acetate, ethyl acetate, methyl methacrylate and ethyl Contains methacrylate.

Polyacetal contains oxymethylene units of 90% or more and 10% or less by weight It is preferred to include one or more co-components.

The melt index (Ml) of polyacetal is according to A37M1238E 0.1 to 30, more preferably 2 to 20 when measured at 190°C/2.16 kg That's good. Suitable polyacetals currently available on the market are 2.5 Ml in 2.16 kg (otherwise referred to as melt flow rate (MFR)) ULTRAFORM B2320 (BASF) with include.

The olefin of the terpolymer can be any olefin of 2 to 5 carbon atoms, e.g. With etheno, propene, butene-1,2-methylpropene-1 or pentene-1 There may be. Etheno or propene, especially etheno, are preferred.

An example of a poly-unsaturated ester monomer that can be used in the terpolymer is vinyl acetate. and acrylates or methacrylates, such as methyl acrylate (methyl methacrylate) methacrylate) and butyl acrylate (butyl methacrylate).

The third monomer of the terpolymer has an ion-dipole interaction with the polyacetal. It is a monomer that imparts the ability to generate to the terpolymer.

Typical monomer proportions of terpolymers are from 50 to 90% by weight, preferably 60% by weight. ~85% by weight α-olefins, 5-45% by weight, preferably 10-35% by weight of polyunsaturated esters and from 1.0 to 20% by weight, preferably from 2 to 15% by weight. monomer (iii) that can be combined with

Polyacetal blends are polyacetals containing at least 50% by weight and up to 50% by weight. It is preferred to include a neutralized terpolymer.

The blend is 70-95% by weight polyacetal and 5-30% by weight neutralized tarpo. It is even more preferable to include a reamer.

Interaction between impact modifiers (i.e., neutralized terpolymers) and polyacetals is an ion-dipole interaction. Dipole is polar polyacetal oxygen Formed between atoms and carbon atoms. In the blend, the impact-modified terpolymer is , preferably ion-neutralized and hence ion-dipole interactions with the polyacetal. generate use.

Neutralization of the terpolymer may be, for example, by amine groups, but e.g. It is preferred that metal ions derived from metal salts or hydroxides be used. . Most preferably, the metal is a transition metal. As used herein, “transition metals” The term “Hand book of Chemistry and P Group 3 of the periodic table published in Hysics, Volume 66 (1985-1986) ~Means transition metals included in Group 12 (new notation). However, the term also contains zinc metal. After all, it is filled with zinc, though.

This is because it has an α-orbital in its electron configuration.

Monomer (5) is an unsaturated monomer containing at least one carboxylic acid group, e.g. Preferably, it is acrylic acid or methacrylic acid. In addition, monomer (ii ) is, for example, an unsaturated monomer containing at least one sulfonic or phosphoric acid group. It may be a mer.

Neutralized impact resistance that is effective for polyacetals by neutralizing terpolymers A preferred method of producing the modifier is to prepare the modifier with an alpha-olefin and a polar unsaturated ester. As third comonomer, for example acrylic acid or its derivatives (for example meth lylic acid, maleic acid or itaconic acid) in the resulting terpolymer. is neutralized with a metal, e.g. a transition metal salt (e.g. acetate) to produce an ionomer. That's true.

The acid may be completely neutralized or partially neutralized.

Neutralization is a process in which the resulting ionomer forms a polyacetal through ion-dipole interactions. This is sufficient space for adhesion. Of course, the amount of neutralization in the unneutralized terpolymer depends on the concentration of acid groups. This gives the blend an impact-improving effect. To obtain an effective level of ion-dipole interaction, it is necessary to use a tag with a low concentration of acid groups. – polymers are neutralized to a greater extent than terpolymers containing high concentrations of acid groups There is a need. Neutralization is, for example, 10 to 90%, more preferably 15 to 35%. You can. Preferred transition metals are zinc, nickel, and cobalt, especially zinc include.

Particularly preferred ionomers are ethylene, methyl acrylate and alrylic acid. -polymer whose terpolymer is fully or partially neutralized with zinc. Ru. The terpolymer contains 60-80% by weight polyolefin, 15-30% by weight Polar unsaturated ester monomer (polyunsaturated ester) and 3-10% by weight Preferably, it contains lylic acid or a derivative thereof.

Ionomers typically range from 0.5 to 15 at 190°C/2.16 kg, generally has an MFR (ASTM I 238E) of 1 to 8, such as about 2. ionomer may be made using techniques known in the art, such as alpha-olefins, A polar unsaturated ester and a monomer (iii) such as acrylic acid are copolymerized to form a tertiary compound. Produces a polymer that is reacted with a neutralizing agent such as a metal acetate to produce an ionomer. may be completed. Such ionomers are commercially available.

Ionomeric impact modifiers are generally used with polyacetals in amounts up to 50% by weight. The exact amount is adjusted depending on the desired impact resistance of the blend.

The impact modifier of the present invention is blended with polyacetal and A fine dispersion of the modifier (e.g. particle size in the range 1-10 μm) can be produced. , the dispersed particles of modifier adhere well to the polyacetal phase.

The pre-neutralized terpolymer may be prepared by copolymerization techniques known in the art.

Blends of polyacetal and modifier may be made by known methods, e.g. For example, by mixing two components together in a mixer to obtain a homogeneous mixture. It's okay to be hit. A typical mixer that may be used is a Brabenc mixer. jer), extruder or internal mixer.

Blends can be formed into molded articles, for example by compression molding, extrusion molding or injection molding. can be manufactured.

The following examples illustrate the invention. Comparative examples are preceded by the letter (C) .

Example 1 Blend the polymer in a laboratory gravender mixer until the torque stabilizes for 2 minutes. Mixed together at 00"C and 4Orpm. Mixing was then continued for an additional 3 minutes to ensure uniform mixing. I got a compound. After removal from the mixing chamber, the blends were heated at 190'C for 1 Compression molding was carried out under a pressure of 0 ton/m" and brought to room temperature. Test specimens were cut from the compression molded products. Ta. The modifiers of this invention are ionomers, which are terpolymers and polyaceters. An ion-dipole interaction occurred between the two. Table I provides details of the blends used and Their properties after molding and molding are shown. The impact strength was measured according to l5ORI80 and The elastic modulus was measured according to AS TMD790MI.

The notched isot impact of the blends of the present invention (e.g., Blends 3 and 7) is compared to a blend containing an equivalent amount of non-ionomeric modifier (e.g., Blend C3). Don't get discouraged. In the blends of the invention, as the ionomer content increases , the notched impact strength increases (see Blends 1-4 and Blends 5-7). and). In contrast, blends containing non-partially neutralized terpolymers (C1-C 4) shows low impact strength and shows no trend with increasing terpolymer concentration.

This may be due to the combination of modifiers and blends such as those present in such blends or the blends of the present invention. This is thought to be due to the lack of improved adhesion between the Trix polyacetals. It will be done. In fact, 01 to C4 are very similar to straight polyacetal (blend C5). They may be found to have impact strengths that differ only slightly. In contrast, books The inventive blends show improvements over straight polyacetals in all cases.

The degree of improvement in impact strength can be determined by adjusting the concentration of neutralized terpolymer and adding polar ester monomers. It can be adjusted by adjusting the chain length in mer (ii).

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Claims (15)

[Claims] 1. Polyacetal and (i) α-olefin of 2 to 5 carbon atoms, (ii) polar (iii) between the terpolymer and the polyacetal. A neutralizable terpolymer that imparts the ability to generate ion-dipole interactions Fully neutralized or partially neutralized terpolymers derived from monomers containing monomers Blend with ma. 2. A blend according to claim 1, wherein (i) is ethylene. 3. (ii) is vinyl acetate, methyl acrylate, butyl methacrylate or A blend according to claim 1 or 2 which is ethyl acrylate. 4. unsaturated where (iii) contains at least one sulfonic or phosphoric acid group; The blend according to any one of claims 1 to 3, which is a blend. 5. Claim (iii) is an unsaturated compound containing at least one carboxylic acid group The blend according to any one of the ranges 1 to 3. 6. Claim 5, wherein (iii) is acrylic acid or methacrylic acid. A blend of. 7. Any of claims 1 to 6, wherein the terpolymer after neutralization contains metal ions. The blend described in item 1. 8. 8. A blend according to claim 7, wherein the metal is a transition metal. 9. The brake according to claim 8, wherein the metal is zinc, nickel or cobalt. nd. 10. The terpolymer contains monomers (i) ethylene, (ii) methyl arylate and and (iii) derivatives derived from acrylic acid and fully or partially neutralized with zinc. The blend according to claim 1. 11. Neutralized center polymer is based on the sum of (i), (ii) and (iii) as 60-85% (preferably 60-80%) of monomer (i); 10-35 % (preferably 15-30%) of monomer (ii); and 2-15% (preferably is derived from monomers contained in a proportion by weight of monomer (iii) of 3 to 10%). A blend according to any one of claims 1 to 10. 12. Claims 1 to 11, wherein the terpolymer is 15% to 35% neutralized. Blend described in either. 13. Claims 1-12 containing at least 50% by weight polyacetal A blend according to any of the paragraphs. 14. 70-95% by weight polyacetal and 5-30% by weight partially neutralized or Claims 1 to 13 include a completely neutralized terpolymer. Blend included. 15. Formed from a blend according to any one of claims 1 to 14. molded product.