JPH03255146A - Vibration-damping resin composition - Google Patents

Abstract

PURPOSE:To improve vibration-damping properties without adversely affecting moldability and impact strength by compounding a specific rubber-modified vinyl arom. polymer with an ethylenic polymer crosslinkable with a metal ion. CONSTITUTION:99.95-99.8wt.% vinyl arom. monomer (e.g. styrene) is copolymerized with 0.05-0.2wt.% vinyl monomer having a glycidyl ester group (e.g. glycidyl methacrylate) in the presence of 2-30wt.% rubberlike polymer (e.g. a butadiene rubber) to give a rubber-modified vinyl arom. polymer (A) wherein particles of the rubberlike polymer are dispersed in a matrix comprising a vinyl arom polymer contg. the vinyl monomer units having the glycidyl ester group. Separately, a copolymer of ethylene with 5-25wt.% carboxylated vinyl monomer (e.g. acrylic acid) is neutralized with 10-90wt.% metal salt (e.g. ZnO) to give an ethylenic polymer (B) crosslinkable with a metal ion. 95-60wt.% polymer (A) is compounded with 5-40wt.% polymer (B).

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an impact-resistant thermoplastic resin composition with excellent vibration damping properties.

[Problems to be solved by conventional technology and invention]) 1rP
Styrenic resins such as high-impact polystyrene and ABS resin, known as s, have excellent moldability and dimensional stability, as well as impact resistance, rigidity, and electrical insulation properties, so they are used in home appliance parts. , 0^ It has come to be used in a wide variety of fields such as equipment parts and vehicle parts.

However, in recent years, in some home appliance fields, such as washing machines, vacuum cleaners, and audio/visual equipment, in order to suppress noise, styrene resins are used to absorb sound and vibration in addition to the above performance. Vibration damping properties are now required.

Conventionally, as a thermoplastic resin having vibration damping properties, a composition in which polypropylene is blended with a large amount of filler such as calcium carbonate is known. However, since these compositions contain a large amount of filler, they have drawbacks such as impairing the inherent properties of the resin (molding processability, impact strength). Therefore, it has been desired to develop a damping material that has the characteristics inherent to resin.

[Means to solve the problem]

As a result of intensive studies to solve the above problems, the present inventors have discovered that a rubber-modified vinyl aromatic polymer with a specific composition and
The present invention was completed by discovering that a resin composition made of a metal ion crosslinkable ethylene copolymer exhibits good vibration damping properties without impairing the excellent moldability and impact strength inherent to the resin.

That is, the present invention provides: A) a rubber-modified vinyl aromatic polymer in which a rubbery polymer is dispersed in the form of particles in a vinyl aromatic polymer matrix containing a vinyl monomer having a glycidyl ester group; (Hereinafter, abbreviated as component A). ) and B) metal ion crosslinkable ethylene copolymer (hereinafter referred to as B)
Abbreviated as ingredient. ) is a resin composition with excellent vibration damping properties.

In the resin composition of the present invention, component A) imparts good moldability, dimensional stability, and rigidity inherent to the resin to the resin composition, while component B) imparts vibration damping properties to the resin composition. do. Although it depends on the final use, the proportion of component B in the resin composition is preferably in the range of 5 to 40% by weight, more preferably in the range of 10 to 30% by weight.

A) Vinyl aromatic polymer matrix containing vinyl monomer units having glycidyl ester groups (hereinafter abbreviated as glycidyl group-modified polymer) used in the present invention refers to vinyl aromatic A vinyl aromatic polymer (hereinafter abbreviated as a glycidyl group-containing copolymer) obtained by copolymerizing a vinyl monomer whose main component is a vinyl monomer and a vinyl monomer having a glycidyl ester group. ) or a polymer obtained by mixing a vinyl aromatic polymer obtained by polymerizing a vinyl monomer whose main component is a vinyl aromatic monomer and the glycidyl group-containing copolymer. Says the matrix becomes more.

Examples of vinyl aromatic monomers include styrene, α-methylstyrene, paramethylstyrene, etc.
Examples include nuclear-substituted vinyl aromatic monomers such as monochlorostyrene, dichlorostyrene, dibromostyrene, and tribromostyrene. These vinyl aromatic monomers may be used alone or in a mixture of two or more.

Further, a small amount of other copolymerizable vinyl monomers may be added to these vinyl aromatic monomers. Other copolymerizable vinyl monomers include vinyl cyanide monomers such as acrylonitrile and methacrylate trile, (meth)acrylic acid ester monomers such as methyl methacrylate and butyl (meth)acrylate, and N-phenylmaleimide. Examples include maleimide monomers such as. These vinyl monomers are suitably used in a proportion of 0 to 50% by weight based on the total amount of the vinyl aromatic monomers.

Glycidyl methacrylate can be mentioned as a monomer having a glycidyl ester group.

The content of monomer units having glycidyl ester groups in the glycidyl group-modified polymer is preferably in the range of 0.05 to 0.2% by weight, and 0.1 to 1.0% by weight.
It is more preferable that it is in the range of .

As the rubbery polymer 7 in component A) used in the present invention,
Examples include butadiene rubber, styrene-butadiene copolymer rubber, polyisoprene rubber, and ethylene-propylene rubber. The content of these rubbery copolymers is
The content is preferably in the range of 2 to 30% by weight from the viewpoint of the impact resistance/rigidity balance of the final composition.

As a method for producing component A) used in the present invention, various known polymerization methods such as bulk polymerization, bulk suspension polymerization, melt polymerization, and emulsion polymerization can be employed.

Specifically, in the presence of the rubbery polymer, the vinyl aromatic monomer, a vinyl monomer having a glycidyl ester group (and a small amount of copolymerizable vinyl monomer as necessary) are added. A method of polymerizing a mixture of monomers) with stirring,
Alternatively, a glycidyl ester group-modified polymer obtained by polymerizing the above polymerization in the absence of a rubbery polymer and a vinyl monomer mainly composed of a vinyl aromatic monomer in the presence of a rubbery polymer. (and if necessary, a small amount of copolymerizable vinyl monomer added) and a rubber-modified vinyl aromatic polymer obtained by polymerizing the mixture with stirring. There is a way.

Component B) and L2 used in the present invention are resins obtained by copolymerizing ethylene and a vinyl monomer containing a carboxyl group and neutralizing the copolymer with a metal salt (generally referred to as an ionomer). is used. The content of vinyl monomers containing carboxyl groups in component B) is preferably from 5 to 25% by weight, more preferably from 10 to 20% by weight. The group is neutralized with a metal salt, preferably 10 to 90% by weight of the total carboxyl group is neutralized with a metal ion, and preferably 20 to 60% by weight of the total carboxyl group is neutralized with a metal ion. It is even more preferable that the

Examples of the vinyl monomer containing a carboxyl group include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, and isocrotonic acid. Preferred are methacrylic acid and acrylic acid. In addition, metal salts used to neutralize carboxyl groups include LiZ NaZ K"+ Mg"+ C
Oxides or hydroxides such as a"Z Zn"+ AI3+ can be mentioned.

Component B used in the present invention is generally produced by melt-mixing a copolymer of ethylene and the above-mentioned carboxyl group-containing monomer together with the above-mentioned metal salt in an extruder or the like. I can do it.

&lllllll type method 7 of the present invention includes A), B
) After tri-blending both components, the mixture is melt-mixed using a single-screw or twin-screw extruder, Nigoo mixer, Banbury mixer, etc., and then subjected to berentization or pulverization.

〔Effect of the invention〕

The resin composition of the present invention has excellent moldability inherent to the resin,
Shows good vibration damping properties without compromising impact strength.

〔Example〕

Examples and comparative examples are given below to specifically illustrate.

In addition, the following samples were used in Examples and Comparative Examples.

*A) Component [rubber-modified vinyl aromatic 1 combination] (A-1
): A rubber-modified vinyl aroma with a rubber content of 9% by weight and a glycidyl methacrylate content of 10.4ml 1% in the total matrix weight, obtained by polymerizing a mixed monomer consisting of styrene and glycidyl methacrylate in the presence of polybutadiene rubber. Polymer (A-2): Rubber-modified polystyrene with a rubber content of 12% by weight obtained by polymerizing styrene in the presence of polybutadiene rubber (A-3) Copolymerizing nigericidyl methacrylate and styrene. Polystyrene (A-5): Rubber content obtained by polymerizing styrene and acrylonitrile in the presence of polybutadiene rubber latex. Rubber-modified vinyl aromatic polymer (A-6) with a weight ratio of 40% and acrylonitrile excluding the rubber component of 25%. Glycidyl methacrylate content obtained by copolymerizing nigericidyl methacrylate, styrene and acrylonitrile: 4 %, vinyl aromatic polymer with an acrylonitrile content of 25% (A, -7): styrene-acrylonitrile copolymer with an acrylonitrile content of 25% (A-1), (A-3) and (A-6) The glycidyl methacrylate content of was determined according to the neutralization titration method.

*n) Component [Metal crosslinkable ethylene copolymer or modified polyolefin] (B-1): 88% by weight of ethylene and 12% by weight of methacrylic acid in the presence of peroxide according to the method for producing high-pressure polyethylene. Ethylene-methacrylic acid zinc methacrylate copolymer with a degree of neutralization of methacrylic acid of 18% obtained by adding zinc oxide to the copolymer obtained in step 7 and melt-mixing in a twin-screw extruder. CB-2): Zinc oxide is added to the copolymer obtained by copolymerizing 84% by weight of ethylene and 16% by weight of methacrylic acid in the presence of peroxide according to the method for producing high-pressure polyethylene. Ethylene-methacrylic acid zinc methacrylate copolymer (B-3) with a degree of neutralization of methacrylic acid of 29% obtained by melt-mixing in an extruder: 88% by weight of ethylene and 12% by weight of methacrylic acid are mixed as peroxide. Ethylene-methacrylic acid copolymer obtained by copolymerization according to the production method of high-pressure polyethylene in the presence of was determined by titration method.

Example 1 8 parts by weight of (A-1) and 20 parts by weight of (B-1) were melt-mixed in a twin-screw extruder to obtain pellets of a resin composition. Next, test pieces were prepared using an injection molding machine, and physical property tests were conducted. The results are shown in Table 1. Note that the physical property test was conducted according to the following method.

・Izotsu impact strength: ASTM D-256 ・Tensile strength; ASTM D-638 ・Flexural modulus: AS
TM D-638 Layer Peeling 2 Based on observation of the fractured surface of the test piece after measuring the above-mentioned Izot impact strength and tensile strength.

・Q-value (resonance sharpness): Using the device shown in the first section, a test piece (ASTM D-638 dumbbell piece) is forced to vibrate non-contact with an electromagnet, and minute displacement is measured. Attach aluminum foil and a piece of iron to both sides of the tip of the test piece, fix the other end as shown in the figure above, and force non-contact vibration at the excitation frequency from the oscillator. (It is then converted into a minute voltage and observed.) A resonance curve based on the relationship between frequency and displacement as shown in the second garden was obtained and calculated using the formula for calculating resonance sharpness.

0 However, fo: Resonant frequency f, I, fL: Frequency that takes a value 3c+e (1/, /T) lower than the displacement of the resonant frequency Example 2 In place of (A-1) 80 parts by weight in Example 1, (A ,
A resin composition was obtained in the same manner as in Example 1, except that 70 parts by weight of -2) and 10 parts by weight of (A-3) were melted and mixed in an extruder. The results are shown in Table 1.

Comparative Example 1 (A-1) Physical properties of a single product were measured. The results are shown in Table 1.

Comparative Example 2 (B-1) The physical properties of a single product were measured. The results are shown in Table 1.

Comparative Example 3 A resin m-parabolite was obtained in the same manner as in Example 1 except that (A-2) was used in place of (A-1) in Example 1. The results are shown in Table 1.

Comparative Example 4 A resin composition was obtained in the same manner as in Example 1 except that (B-3) was used in place of (B-1) in Example 1. The results are shown in Table 1.

Example 3 A resin composition was obtained in the same manner as in Example 1 except that (B-2) was used in place of (B-1) in Example 2. The results are shown in Table 1.

Example 4 In place of 80 parts by weight of (1-1) in Example 1, (A-
2) 30 parts by weight, (A-3) 10 parts by weight and (A-4)
A resin composition was obtained in the same manner as in Example 1, except that 40 parts by weight were melt-mixed in an extruder in advance. The results are shown in Table 1.

Example 5 In place of 10 parts by weight of (A-3) in Example 2, (A-
3) Except using 2 parts by weight and 8 parts by weight of (A-4),
Examples 1 and 1. A resin composition was obtained in the same manner as iJ. The results are shown in Table 1.

Example 6 (A-5) 30 parts by weight, (A-6) 15 parts by weight and (A
-7) Resin composition obtained by melt-mixing 30 parts by weight of a rubber-modified vinyl aromatic polymer obtained by melt-mixing in an extruder and 25 parts by weight of (B-1) in a twin-screw extruder. I got it.

The results are shown in Table 1.

Comparative Example 5 Resin &I1. I got a fresh product.

The results are shown in Table 1.

Comparative Example 6 A resin composition was obtained in the same manner as in Example 6 except that (B-3) was used in place of (B-1) in Example 6. The results are shown in Table 1.

Comparative Example 7 1511 L parts of (A-6) and (A-
7) A resin composition was obtained in the same manner as in Example 6, except that 45 parts by weight of (A-7) was used instead of 30 parts by weight. The results are shown in Table 1.

Margin below

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a method for measuring the Q-value, and FIG. 2 shows a resonance dose line based on the relationship between frequency and displacement used in the method for calculating the Q-value.

Claims (1)

[Scope of Claims] 1. A) In a vinyl aromatic polymer matrix containing vinyl monomer units having glycidyl ester groups,
A vibration-damping resin composition comprising: a rubber-modified vinyl aromatic polymer in which a rubber-like polymer is dispersed in the form of particles; and B) a metal ion crosslinkable ethylene polymer.