JPH10204247A - Permanent antistatic styrenic resin composition and molded article thereof - Google Patents

Abstract

(57) [Summary] (with correction) [PROBLEMS] To provide a rubber-modified styrenic resin composition exhibiting permanent antistatic performance and excellent in appearance performance and the like. SOLUTION: A copolymer composed of a monomer unit having a quaternary ammonium group and a vinyl or vinylidene monomer unit copolymerizable therewith is added to 100 parts by weight of a rubber-modified styrene resin. (1) a weight average particle diameter of the dispersed particles of the rubbery polymer in the rubber-modified styrene resin is 0.4 to 0.9 μm; The 5% value of the cumulative particle size distribution on a weight basis is 1.0 μm or less, and the 95% value is 0.
(2) A styrene-based resin composition having a permanent antistatic property, wherein the proportion of dispersed particles having a salami structure in the dispersed particles of all rubbery polymers is at least 80% by weight. [Effect] It is extremely useful as a plastic material used in automobile interior parts and home appliances where appearance is regarded as important.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a permanent antistatic styrenic resin composition having good mechanical properties and good appearance, and a molded product thereof.

[0002]

2. Description of the Related Art In recent years, the cost of various home appliances and OA equipment has been reduced, and there is a strong demand for lowering the cost of housings, covers, and the like used therefor, without the need for painting and other secondary processing. There is a demand for a resin having a new function on the surface and good appearance. On the other hand, resin products such as housings are generally electrically insulative, so they are easily charged by friction, peeling, etc., resulting in inconvenience such as dirt or dust adhering to the outer surface or sticking of paper or film. . In addition, there are various obstacles in the field of other molded products, films, sheets, etc. In particular, recently, in order to prevent malfunction and damage of ICs in packaging materials for electronic parts and housings of electronic equipment, reliability has been reduced. There is a demand for an antistatic material having a high level.

[0003] In general, such antistatic properties are imparted to plastics by (1) making the resin itself a conductive molecular structure or introducing a large amount of a hydrophilic group into the resin itself; ) Kneading a conductive filler, for example, carbon black or metal powder, (3) applying an antistatic agent such as a surfactant or a hydrophilic resin to the surface of the resin molded product;
(4) An antistatic agent such as a surfactant or a hydrophilic resin is kneaded into a resin to which an antistatic property is to be imparted.
However, the method (1) is poor in practicality in terms of stability, mechanical properties, production cost, etc. of the conductive resin and hydrophilic group-introduced resin to be used, and is not industrially suitable. Also,
Although the method (2) is used industrially, the mixability of the conductive filler impairs the moldability, colorability, appearance of the molded product, and the like, so that the method is limited and lacks versatility. The method (3) has also been attempted for large molded products, but is currently industrially limited due to problems such as cost increase and surface defects due to the coating process.

[0004] On the other hand, the method (4) has few disadvantages as described above and can respond to user needs relatively well.
It is widely used industrially for the purpose of preventing static electricity of general-purpose resins such as acrylic resins and engineering plastics. When a surfactant is used as an antistatic agent, there is a problem in durability, and the surfactant transferred to the surface of the resin molded product is easily removed from the molded product surface by washing or wiping during use. Therefore, they are not suitable for applications requiring permanent antistatic properties. In particular, recently, permanent antistatic properties such that antistatic effects are not lost even under general use conditions assuming cleaning with a cleaning solution and rubbing off of friction, for various resin molded products mainly for housings of OA equipment and AV equipment. The need for grants is increasing. In such a case, use a hydrophilic resin having an appropriate affinity (compatibility) with the resin and an appropriate molecular weight so that the hydrophilic resin is not easily removed by washing or wiping when the molded article is used, and melt-knead the hydrophilic resin into a matrix. A method of dispersing in a resin is generally used.

As a specific example of imparting permanent antistatic properties by melting and kneading a hydrophilic resin with a styrene resin,
For example, a method using a polyetheramide elastomer to which a polyamide elastomer hydrophilic resin is applied and a modified vinyl polymer (Japanese Patent Publication No. 4-72855),
A method using a polyetheramide elastomer and a maleimide copolymer resin (JP-A-63-227648) and a method using a polyamideimide elastomer and a modified styrene resin (JP-A-2-255850) are known. And a number average molecular weight of 50,000 to 100 utilizing a polyalkylene oxide-based hydrophilic resin.
Using polyethylene oxide and a sulfonate (Japanese Unexamined Patent Publication No. 2-233743), molecular weight 5000
A method using a polyethylene wax obtained by grafting 20% or more of polyethylene glycol and styrene as described above (JP-A-4-23847) is also known.

However, in order to impart permanent antistatic properties to a styrenic resin by using the above-mentioned polyamide elastomer or polyalkylene oxide, it is necessary to incorporate a large amount of such a hydrophilic resin. However, there is a problem in that the various properties of these materials are greatly reduced and the material price is increased. In addition, the mechanism of expressing the antistatic performance of the polyamide elastomer, polyalkylene oxide, or the like is governed by the moisture absorption rate of these resins, so that there is a problem that the antistatic effect is not easily exerted immediately after molding. Therefore, as a method for expressing the antistatic effect immediately after molding, a method of adding a random copolymer comprising a quaternary ammonium base and a vinyl monomer or a vinylidene monomer copolymerizable therewith to a thermoplastic resin. (JP-A-63-54467) is known. However, the method of adding the above random copolymer requires that the surface gloss of the molded article is poor and the affinity (compatibility) with the resin is poor depending on the matrix of the thermoplastic resin used, particularly the rubber-modified styrene resin. There were problems such as insufficient surface appearance performance such as generation of surface silver and flow marks.

[0007] Conventional rubber-modified styrenic resin compositions include:
In order to obtain impact resistance, the particle size (rubber particle size) of the rubbery polymer is usually set to 1 to 3 μm and dispersed in a styrene resin, but is generally used for applications requiring an appearance due to poor gloss. There was a problem that it was difficult. Therefore, in order to improve the balance between impact resistance and gloss, a method of compensating impact resistance by adding silicone oil or the like to a rubber-modified styrene resin having a rubber particle system of 1 μm or less (Japanese Patent Publication No.
JP-B-76338, JP-B-5-11143, and JP-B5-45624), and a method of adjusting the ratio of the gel component to the rubber component (JP-B-7-53816).
Publication). However, these methods still have insufficient impact strength and rigidity balance.

In Japanese Patent Publication No. 3-62323 and Japanese Patent Publication No. 1-34533, the coloring property and appearance are controlled by adjusting the average particle diameter of the aromatic vinyl polymer contained in the rubber-like substance. It has been proposed to improve
In addition, a method has been proposed in which rubber particles having a core-shell structure and rubber particles having a salami structure are blended to form a bimodal rubber particle size distribution, but these methods all exhibit high gloss measurement values. Is lacking in glossiness (definition of a reflected image) when an actual molded article is visually evaluated, or when the antistatic agent of the present invention is added, the gloss inherent in the resin alone greatly increases There are problems such as lowering, and it has been difficult to achieve both antistatic performance and appearance performance even when the above antistatic agent is added to these resins.

[0009]

SUMMARY OF THE INVENTION In view of the above situation, an object to be solved by the present invention is to provide a permanent antistatic property by adding a small amount of an antistatic agent without substantially impairing the balance of mechanical properties of the base resin. An object of the present invention is to provide a styrenic resin composition that exhibits excellent surface gloss, is excellent in controlling defects such as flow marks, and is excellent in appearance performance when colored.

[0010]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that a specific rubber-modified styrenic resin has a monomer unit having a specific quaternary ammonium base. By combining and combining the copolymer as an essential component as an antistatic agent, it is possible to satisfy permanent antistatic properties, to have good surface gloss, to further suppress defects such as flow marks, and to have excellent appearance performance when colored. Heading, the present invention has been reached.

That is, the present invention relates to a monomer unit having a quaternary ammonium base, based on 100 parts by weight of a rubber-modified styrene resin obtained by dispersing a rubbery polymer in a styrene resin matrix. A styrene resin composition containing 1 to 10 parts by weight of a copolymer comprising a vinyl or vinylidene monomer unit copolymerizable with (1) a rubber-like polymer in the rubber-modified styrene resin; The weight average particle diameter of the combined dispersed particles is 0.4 to 0.9 μm
And the weight-based cumulative particle size distribution of 5
% Value is 1.0 μm or less, 95% value is 0.2 μm or more, (2) the proportion of the dispersed particles having a salami structure in the dispersed particles of the whole rubbery polymer is 80% by weight or more, and The number of dispersed particles in which the number of particles of the aromatic vinyl polymer contained in the whole rubber-like polymer dispersed particles is 20 or less is 70% or more of the total dispersed particles, and (3) the toluene-insoluble matter and the rubber A permanent antistatic styrenic resin composition having a component ratio in the range of 1.0 to 2.5.

Further, according to the present invention, the above-mentioned copolymer comprises 20 to 80% by weight of a monomer unit having a quaternary ammonium group represented by the following formula (I): Or 80 to 20% by weight of vinylidene monomer unit
And the weight average molecular weight Mw of the copolymer is 20
000 to 1,000,000, and the molecular weight distribution represented by the ratio of the weight average molecular weight Mw to the number average molecular weight Mn is 3
-10. (Where R ₁ is a monovalent group having a polymerizable carbon-carbon double bond, and R ₂ , R ₃ and R ₄ are hydrogen or a C 1-9 carbon atom which may have a substituent.) alkyl group, X ^- is 1
It represents a valent inorganic or organic acid radical or the corresponding equivalent of an inorganic or organic acid. )

Further, the present invention relates to 100 parts by weight of the permanent antistatic styrenic resin composition of the present invention.
Further, 0.3 to 10 parts by weight of an alkyl sulfonate or an aromatic sulfonate is blended. Furthermore, the present invention relates to a molded article obtained by molding the above-mentioned permanent antistatic styrenic resin composition, wherein a copolymer type antistatic is provided on the surface layer of the molded article from the surface of the molded article to a depth of 20 μm. The agent is dispersed in a resin forming a matrix as streak particles, and the weight-average major axis of the streak particles is 0.5 to 100 μm and the average aspect ratio is 50 to 500 in a cross section in the depth direction. A styrenic resin molded article characterized by the following.

Hereinafter, the present invention will be described in detail. The rubber-modified styrene-based resin obtained by dispersing a rubber-like polymer in a styrene-based resin matrix used in the present invention is an aromatic vinyl-based monomer such as styrene in the presence of a rubber-like polymer, or And further polymerized in the co-presence of another copolymerizable vinyl monomer. Here, as the aromatic vinyl monomer, styrene,
α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, vinylethylbenzene,
Vinyl xylene, vinyl naphthalene and the like can be mentioned. Other vinyl monomers copolymerizable with the aromatic vinyl monomer include methyl methacrylate, ethyl methacrylate, methyl acrylate, ethyl acrylate, acrylonitrile, methacrylonitrile, methacrylic acid, and acrylic acid. , Maleic anhydride, phenylmaleimide, or a halogen-containing vinyl monomer. These copolymerizable monomers may be used alone,
Two or more kinds may be combined, but usually 30% by weight or less, based on the total aromatic monovinyl monomer containing styrene,
Preferably, it is used in a proportion of 10% by weight or less.

The rubbery polymer used in the present invention is not particularly limited, and polybutadiene, styrene-butadiene copolymer, polyisoprene, butadiene-styrene polyisoprene copolymer, natural rubber and the like can be used. When polybutadiene is used for the rubbery polymer, the microstructure of the polybutadiene portion may be low-cis polybutadiene rubber, high-cis polybutadiene rubber, or low-cis polybutadiene rubber and high-cis polybutadiene rubber. It may be a mixture of polybutadiene rubber. The structure of the styrene-butadiene copolymer rubber may be a random type, a block type or a taper type. One of these rubbery polymers can be used alone, or two or more can be used in combination.

The content of the rubbery polymer dispersed in the rubber-modified styrenic resin is preferably in the range of 4 to 15% by weight, and particularly preferably in the range of 7 to 15% by weight. If the content of the rubbery polymer is less than 4% by weight, the impact resistance is insufficient, and if it exceeds 15% by weight, the rigidity is reduced to a practical range or less, which is not preferable. In the rubber-modified styrene resin composition, in order to achieve the object of the present invention, the weight average particle diameter of the rubber-like polymer dispersed particles is 0.4 to 0.9 μm, preferably 0.4 to 0.7 μm.
It needs to be μm. 0.4 weight average particle size
If it is less than μm, the impact resistance is insufficient, and if it exceeds 0.9 μm, the gloss is significantly reduced. The weight average particle diameter was determined by the following equation by taking an electron micrograph of the rubber-modified styrene resin by an ultra-thin section method and measuring the particle diameter of 1,000 or more dispersed rubber particles in a photograph magnified 10,000 times. Shall be. Weight average particle size = ΣniDi ⁴ / niDi ³ (where ni is the number of rubber-like polymer particles having a particle size Di).

In order to achieve the object of the present invention,
5 of weight-based cumulative particle size distribution of rubbery polymer dispersed particles
% Value is 1.0 μm or less, preferably 0.9 μm or less, 9% or less.
It is necessary that the 5% value be 0.20 μm or more, preferably 0.25 μm or more. It is essential that the 5% value of the weight-based cumulative particle size distribution be 1.0 μm or less in order to obtain excellent gloss. In addition, rubber-like polymer particles having a 95% value of 0.20 μm or less cannot be expected to have an impact absorbing effect, so that the impact resistance is undesirably reduced. In addition, 5% of the weight-based cumulative particle size distribution of the rubber-like polymer dispersed particles referred to herein.
The value of 95% means that the rubber particles are accumulated from the larger one, and the particle diameter at which the weight-based accumulation ratio is 5% of the whole is represented by the 5% value of the cumulative particle diameter distribution. It means a value expressed as a 95% value of the cumulative particle size distribution.

Further, in the present invention, in order to obtain a target in the balance of physical properties of mechanical strength, particularly in impact resistance,
It is necessary to control the dispersed rubber-like polymer particles in a specific dispersion form. That is, it is necessary that the rubber-like polymer dispersed particles have a salami structure. Here, the dispersed particles having a salami structure are those in which two or more aromatic vinyl polymer particles are included in the dispersed particles, and in the present invention, the particles have a salami structure occupying in all the dispersed particles. It is necessary that the ratio of the dispersed particles is 80% by weight or more. If the proportion of the dispersed particles having a salami structure is less than 80% by weight, the impact resistance is reduced.

Further, according to the present invention, the number of particles of the aromatic monovinyl polymer contained in the rubber-like polymer dispersed particles is 2
It is necessary that the number of dispersed particles of 0 or less is 70% or more, preferably 80% or more of the total number of dispersed particles. Here, the included aromatic monovinyl polymer particles are:
An electron micrograph of the rubber-modified aromatic monovinyl resin was taken by an ultra-thin section method, and in a photograph magnified 10000 times, the minor axis was 0.3 mm, that is, 0.03 μm.
Means the above particles. If the number of the dispersed particles in which the number of particles of the aromatic monovinyl polymer included is 20 or less is less than 70% of the total dispersed particles, the glossiness of the molded article is reduced.

Further, in the present invention, in order to obtain a target in terms of the balance of physical properties of mechanical strength, particularly impact resistance, the ratio of the rubber-modified styrene resin in toluene-insoluble component to the rubber component is 1.0 to 1.0. It must be in the range of 2.5. If the ratio is less than 1.0, there is a problem that the impact resistance is significantly reduced. On the other hand, if the ratio is 2.5 or more, the rigidity is greatly reduced, and there is a problem that a satisfactory balance of physical properties cannot be obtained. Here, the measurement of the toluene-insoluble content means the insoluble content when 1 g of the resin is dissolved in 30 ml of toluene. In the present invention, the radius is 11.4 cm by a centrifuge.
The insolubles were separated at 14000 rpm and 20 ° C. for 30 minutes using a rotor, and dried to remove toluene. Then, the weight of the toluene insolubles was measured and determined by the following equation. Toluene-insoluble matter (% by weight) = (Weight of toluene-insoluble matter /
Weight of resin composition) × 100

The rubber-modified styrenic resin composition of the present invention preferably contains 0.005 to 0.5% by weight of silicone oil. Silicone oil content
If the amount is less than 0.005% by weight, the effect of improving the impact resistance is reduced. If the amount is more than 0.5% by weight, not only does the effect of adding the silicone oil plateau, but also the resin bleeds on the surface of the molded product when molded and has an appearance. Problems such as failure may occur. The silicone oil to be used is not particularly limited.
Silicone oil in the range of 2222 dyne / cm is particularly effective, and the effect is exhibited with a small amount of addition. If the surface tension of the silicone oil is out of the range of 19 to 22 dyne / cm, the impact resistance is undesirably reduced.

The antistatic agent used in the present invention includes
Monomeric units having quaternary ammonium bases and copolymers
Co-polymer with vinyl or vinylidene monomer
It is preferred that they are united. Here, the fourth grade Ammoniu
A monomer unit having a base is represented by the following general formula (1).
Preferably.(Where R₁Has a polymerizable carbon-carbon double bond.
A monovalent group R_Two, R _ThreeAnd R_FourRepresents hydrogen or a substituent
Optionally having an alkyl group having 1 to 9 carbon atoms, X^-Haichi
Valent inorganic or organic acid groups or inorganic or organic acids
Represents the corresponding equivalent of. )

A method for producing such a copolymer is known, and the method can be employed in the present invention. However, 20 to 80% by weight of the monomer unit represented by the above formula (I) And 80 to 20% by weight of a copolymerizable monomer unit. In the above formula (I), R ₁ is a monovalent group having a polymerizable carbon-carbon double bond, and is preferably a group represented by the following formula (II). However, in the formula, R ₅ represents hydrogen or a methyl group, and n is 1 to
It is an integer of 10 and preferably 2 to 6. Y represents O or NH.

In the present invention, the monomer unit represented by the above formula (I) having a quaternary ammonium salt which is a component of the copolymer capable of imparting antistatic properties is a polymerizable monomer having an amine. Is quaternized by a quaternizing agent. The amine-containing polymerizable monomer is, for example, (meth) acrylate, (meth) acrylamide, styrene or the like in which an amino group is introduced, and in particular, amine-containing (meth) acrylate and (meth) acrylamide are preferable. Specific examples of the acrylate or methacrylate having an amine include dimethylaminoethyl acrylate, diethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, dimethylaminopropyl methacrylate,
Examples include dimethylaminobutyl methacrylate, dipropylaminoethyl methacrylate, dibutylaminoethyl methacrylate, dihydroxyethylaminoethyl methacrylate, and the like.

Specific examples of (meth) acrylamide having an amine include dimethylaminoethyl acrylamide, diethylaminoethyl acrylamide, dimethylaminoethyl methacrylamide, diethylaminoethyl methacrylamide, dimethylaminopropyl methacrylamide, dimethylaminopropyl acrylamide, and dimethylaminoethyl acrylamide. Examples include aminobutyl methacrylamide, dipropylaminoethyl methacrylamide, dibutylaminoethyl methacrylamide, dihydroxyethylaminoethyl methacrylamide, and the like.

Examples of the quaternizing agent include alkyl sulfates such as dimethyl sulfate, diethyl sulfate, and dipropyl sulfate; sulfonates such as methyl p-toluenesulfonate and methyl benzenesulfonate; alkyl sulfites such as dimethyl sulfite; Examples include alkyl phosphoric acids such as trimethyl phosphate, and various halides such as alkyl benzene chloride, benzyl chloride, alkyl chloride, and alkyl bromide. Among them, alkyl sulfates and sulfonic esters are preferable from the viewpoint of heat stability.

The copolymer capable of imparting antistatic properties according to the present invention contains 20 to 80% by weight, preferably 30 to 70% by weight of a monomer unit having a quaternary ammonium group represented by the above formula (I). And a vinyl monomer unit or a vinylidene monomer unit copolymerizable therewith is 80 to 2 units.
Those comprising 0% by weight, preferably 70 to 30% by weight are preferred. When the amount of the monomer unit having a quaternary ammonium base is less than 20% by weight, the antistatic performance is not sufficient, and when it exceeds 80% by weight, the compatibility with the styrene resin composition is deteriorated, and It is not preferable because the durability of the preventive property is reduced.

The vinyl monomer or vinylidene monomer copolymerizable with the above-mentioned monomer unit having a quaternary ammonium base includes styrene, α-methylstyrene, p-methylstyrene, p-methylstyrene and p-methylstyrene. Aromatic vinyl compounds such as tert-butylstyrene and 3,4-dimethylstyrene, vinyl cyanide monomers such as acrylonitrile and methacrylonitrile, and methyl, ethyl, propyl, n-butyl and acrylic acid of acrylic acid or methacrylic acid C1-C18 alkyl esters such as butyl, hexyl, 2-ethylhexyl, dodecyl and octadecyl; esters such as ethylene glycol, propylene glycol, butanediol; vinyl esters of C1-C6 carboxylic acids such as acetic acid and propionic acid; acrylics Acid, methacrylic acid, maleic acid, etc. Unsaturated carboxylic anhydrides such as saturated carboxylic acid and maleic anhydride, (meth) acrylamides such as acrylamide, methacrylamide, N, N-dimethylacrylamide, maleimide, N-methylmaleimide, N-ethylaremid, N- N-substituted maleimides such as phenylmaleimide and N-cyclohexylmaleimide, alkyl vinyl ethers, alkyl vinyl ketones, vinyl chloride, vinylidene chloride, isobutene and the like are included, and styrene, butyl acrylate, acrylonitrile, methyl methacrylate, and maleic anhydride are particularly preferable. .

These monomers can be used alone or in combination of two or more. Antistatic is achieved by selecting a highly polar monomer such as acrylonitrile or a monomer containing an ionic substituent such as sulfonic acid group, phosphoric acid group or carboxylic acid group among these copolymerizable monomers. It is preferable because the property is further improved. The use of the same monomer as the rubber-modified styrenic resin, which is the base resin, or the same as the resin having good compatibility is particularly advantageous in that the properties such as the durability of the antistatic property and the strength of the base resin are maintained. is there.

The weight average molecular weight of the copolymer capable of imparting antistatic properties in the present invention is preferably from 200,000 to 1,000,000, particularly preferably from 300,000 to 600,000. If the weight average molecular weight is less than 200,000, a good streaky structure is not formed in the surface layer of the molded product, and a large amount of addition is required to exhibit antistatic performance, which is disadvantageous in terms of cost and It is not preferable because physical properties, particularly impact resistance, are reduced. Also, 100
When the number exceeds 10,000, polymerization is difficult and coarse dispersion is liable to occur, so that not only is the surface resistivity poor, but also delamination of a molded article occurs, which is not preferable. The preferred molecular weight distribution is in the range of 3 to 10, particularly preferably 5 to 10. When the molecular weight distribution is narrower than 3, it is not preferable because a plasticizing effect is lost because relatively low molecular weight components are not contained and the melt viscosity increases, and the antistatic agent hardly migrates to the surface of the molded article. On the other hand, if it exceeds 10, undesirably, the appearance will be poor due to the effect of a large amount of components such as brush.

It is preferable that the ratio of the melt viscosity of the copolymerization type antistatic agent to the melt viscosity of the base resin at the same temperature under an effective shear rate during melt kneading is in the range of 1.2 to 0.5, More specifically, the melt viscosity of the copolymerization type antistatic agent is set to an effective shear rate of 45 during melt kneading.
(S ^-1 ) is preferably in the range of 200 to 3000 (Pa · s). Further, the ratio of the solubility parameter (SP value) between the copolymer type antistatic agent and the base resin is preferably in the range of 1.02 to 1.5, and 1.02 to 1.1 to prevent delamination. Is more preferable.

The polymerization method of the copolymer type antistatic agent is not particularly limited, but usually, a method such as melt polymerization in the presence of a radical polymerization initiator and bulk polymerization can be used. It is also preferable to carry out drop polymerization in order to make the copolymerization proceed well. Further, a crosslinking agent can be used in combination to facilitate production of a copolymer having a large molecular weight and a wide molecular weight distribution. Examples of the type of the crosslinking agent include divinyl compounds that can react with a vinyl monomer or a vinylidene monomer. Specifically, p-divinylbenzene, o-divinylbenzene, 2,6-divinylnaphthalene, -4'-divinyldiphenyl, ethylene glycol dimethacrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylamide, ethylene glycol diacrylamide, etc., among which ethylene glycol dimethacrylate and p-divinylbenzene are preferred.

The amount of the crosslinking agent to be used is 1 part by weight, preferably less than 0.5 part by weight, based on all vinyl monomers or vinylidene monomers. If the amount is too large, a part of the polymer gelled is mixed into the polymer, which is not preferable because the surface is roughened or coarsely dispersed when a molded article is formed.
It is also effective to adjust the method of adding the initiator as a method of adjusting the molecular weight distribution. The compounding amount of the copolymer capable of imparting the antistatic property is the rubber-modified styrenic resin composition 10
It is 1 to 10 parts by weight, preferably 1 to 7 parts by weight based on 0 parts by weight. If the amount is less than 1 part by weight, the antistatic property cannot be imparted. If the amount exceeds 10 parts by weight, the physical properties of the base resin tend to be impaired, and it is not preferable from the viewpoint of cost.

In the composition of the present invention, in order to improve the antistatic property and further improve the appearance performance of a molded article of the resin composition, for example, to improve gloss and suppress silver, flow mark, etc., an organic compound is used. An electrolyte such as an alkyl sulfonate or an aromatic sulfonate can be added. Examples of the organic compound include dodecylbenzenesulfonic acid, p-toluenesulfonic acid, dodecyldiphenyletherdisulfonic acid, naphthalenesulfonic acid,
Condensates of naphthalenesulfonic acid and formalin, aromatic sulfonic acids such as polystyrenesulfonic acid, octylsulfonic acid, nonylsulfonic acid, decylsulfonic acid, undecylsulfonic acid, laurylsulfonic acid, tridecylsulfonic acid, tetradecylsulfonic acid, Examples thereof include alkyl sulfonic acids having 5 to 40 carbon atoms such as pentadecylsulfonic acid, hexadecylsulfonic acid, heptadecylsulfonic acid, and stearylsulfonic acid, and alkali metal salts and alkaline earth metal salts thereof. Sodium acid and sodium alkyl sulfonate are preferred. These may be used alone or in combination of two or more.

Further, organic carboxylic acids such as stearic acid, lauric acid and polyacrylic acid, organic phosphoric acids such as diphenyl phosphite and diphenyl phosphate, and alkali metal salts and alkaline earth metal salts thereof are used in combination. You may. These also exert their effects in the form of a free acid, but are preferably used in the form of an alkali metal salt or an alkaline earth metal salt, such as sodium, lithium, potassium, magnesium and calcium salts. .

The compounding amount of the organic compound for synergistically improving the antistatic performance and appearance performance is 0.1 to 100 parts by weight of the rubber-modified styrene resin composition containing the antistatic agent.
It is 3 to 10 parts by weight, preferably 0.5 to 5 parts by weight.
When the amount is less than 0.3 parts by weight, the antistatic performance is not synergistically improved, and the appearance performance of the molded article, for example, the effect of improving gloss and suppressing silver, flow mark and the like is small. If the amount exceeds 10 parts by weight, the physical properties of the base resin tend to be impaired, and this is not preferable from the viewpoint of cost.

The permanent antistatic styrenic resin composition of the present invention can be used in combination with another antistatic agent to further improve the antistatic performance. Although commonly used antistatic agents can be used, a surfactant type antistatic agent having a hydrophilic group and a hydrophobic group is preferable, for example, alkyl sulfate, alkyl allyl sulfate, and alkali acid. Anionic antistatic agents such as phosphates and alkyl phosphates; cationic antistatic agents such as amine neutralized salts, quaternary ammonium salts and complex ionic salts; zwitterionic antistatic agents such as betaine, sulfobetaine and heavy metal salts / Anionic / cation neutralized antistatic agents such as neutralized alkylamine fatty acids, nonionic antistatic agents such as sorbitan fatty acid esters, monoglycerides, poly (alkylene oxide) (co) polymers, and trialkyl phosphates, amine oxides , Bisglyceryl borate monoalkylate, etc. semipolar antistatic . In particular alkyl sulfates, alkylaryl sulfates are preferred.

Further, as long as the object of the present invention is not hindered,
Inorganic fillers such as glass fiber, carbon fiber, ceramic fiber, mica, talc, calcium carbonate and barium sulfate can be added. In the present invention, a plasticizer, a release agent, a weathering agent, an antioxidant, a flame retardant, a colorant, a stabilizer and other additives may be added for various purposes.

Although the resin composition of the present invention is excellent in sustained antistatic performance, when the composition is molded into a molded article, the surface of the molded article from the surface of the molded article to a depth of 20 μm is charged. The inhibitor is dispersed as streak-like particles, and the weight-average major axis of the streak-like particles in the cross section in the depth direction is 0.5 to 1
When the particles are dispersed in the range of 00 μm and the average aspect ratio in the range of 50 to 500, the antistatic performance is more excellent. The resin composition of the present invention is characterized in that when the composition is molded, it is easily dispersed as streaky particles. In order to more effectively generate a shape in which the particles are dispersed as streak-like particles, shearing force, high-speed deformation, and the like can be given. Therefore, a molding method such as high-speed extrusion, injection, and inflation is particularly preferable.

The dispersion state of the antistatic agent particles in the molded article is determined by dyeing the resin molded article by osmium tetroxide staining method.
By taking ultra-thin section transmission electron micrographs, it can be judged with the naked eye. The final product form using the permanent antistatic styrenic resin composition of the present invention includes various molded products such as radio and television, housings for OA equipment, case parts such as covers, lighting equipment parts, plastic containers, ribbons, Examples of such materials include tapes, films, sheets and the like, which require antistatic properties and appearance performance.

[0041]

BEST MODE FOR CARRYING OUT THE INVENTION The permanent antistatic styrenic resin composition of the present invention is produced by mixing the above-mentioned copolymer type antistatic agent and a rubber-modified styrenic resin composition.
There is no particular limitation on the mixing method, various rolls, internal mixers with two rotors such as Banbury mixers,
After melt-kneading with a screw-type single-screw extruder or twin-screw extruder and pelletizing, it can be molded using an injection molding machine, an extrusion molding machine, a blow molding machine, etc. according to the use and shape of the molded product. it can.

[0042]

The embodiments of the present invention will be specifically described below with reference to examples and comparative examples. The processing conditions and physical property evaluation conditions in each of the following Examples and Comparative Examples were performed by the following methods. -Molecular weight measurement GPC measurement was performed using polyethylene oxide as a standard sample and using acetonitrile / water as an eluent. -Kneading Pelletization was carried out at a cylinder temperature of 210 ° C and a screw rotation speed of 100 rpm with a twin screw extruder of 30 mmφ manufactured by Ikegai Co., Ltd. Molding The molding was performed at a cylinder temperature of 210 ° C. and a mold temperature of 40 ° C. using a 100 t injection molding machine manufactured by Toshiba Machine Co., Ltd.

[0043] Surface Measurement of the evaluation surface resistivity R ₀ of resistivity R ₀ is fabricated by injection molding 10
A flat plate of 0 mm x 100 mm x 3 mm is heated at 23 ° C and 50%
Immediately after the injection molding under the RH condition, it was measured at an applied voltage of 1000 V with a super insulation meter SM8210 manufactured by Toa Denpa Kogyo Co., Ltd., and the 1 minute value was adopted.・ Evaluation of surface resistivity R ₁ The surface resistivity R ₁ was measured by injection molding.
A flat plate of 0 mm x 100 mm x 3 mm is heated at 23 ° C and 50%
After humidifying for about one day under the RH condition, it was measured with a super insulation meter SM8210 manufactured by Toa Denpa Kogyo Co., Ltd. at an applied voltage of 1000 V, and a value of 1 minute was adopted.

[0044] Surface Measurement of the evaluation surface resistivity R ₂ resistivity R ₂ was prepared by injection molding 10
A flat plate of 0 mm x 100 mm x 3 mm is heated at 23 ° C and 50%
After humidifying for about 7 days under RH conditions, measurement was performed at an applied voltage of 1000 V with a super insulation meter SM8210 manufactured by Toa Denpa Kogyo Co., Ltd., and a value of 1 minute was adopted. Evaluation of surface resistivity R ₃ The surface resistivity R ₃ was measured by injection molding.
A plate of 0 mm × 100 mm × 3 mm is sufficiently washed with distilled water to remove water on the surface, and then heated at 23 ° C. and 50% R
After controlling the humidity for about 1 hour under the H condition, it was measured at an applied voltage of 1000 V with a super insulation meter SM8210 manufactured by Toa Denpa Kogyo Co., Ltd., and the 1 minute value was adopted.

Evaluation of Izod impact value Izod impact value was measured according to ASTM D-256. Evaluation of Gloss Gloss was measured according to JIS K7105.・ Evaluation of external appearance The external appearance was evaluated by 100 mm × 1 produced by injection molding.
A flat plate of 00 mm × 3 mm was visually observed to confirm the coloring property at the time of black coloring and the presence or absence of appearance defects such as silver and flow marks.

Reference Example 1 Production Example of Copolymer Type Antistatic Agent In a reactor equipped with a stirring blade, 100 parts by weight of dimethylaminopropylacrylamide as a monomer having a tertiary amine was added.
120 parts by weight of methanol and 1 part by weight of hydroquinone monomethyl ether as a polymerization inhibitor were added, and the mixture was stirred at a temperature of 20 ° C. or lower so that dimethylaminopropylacrylamide was not homopolymerized during quaternization.
A mixture of 10 parts by weight of methanol and 10 parts by weight of methanol was added dropwise over 1 hour. After the completion of the dropwise addition, the mixture was further stirred for 30 minutes to complete the quaternization, thereby obtaining a monomer solution having a quaternary ammonium salt. Add azobisisobutyronitrile 1 to this solution.
Parts by weight, 100 parts by weight of styrene and 300 parts by weight of N, N-dimethylformamide were added, and the mixture was polymerized at a reaction temperature of 65 ° C. under a nitrogen atmosphere for 6 hours. After completion of the polymerization, the reaction solution is
Vacuum drying was performed at 0.5 ° C. and 0.5 mmHg to obtain a copolymer type antistatic agent. The weight average molecular weight (M
w) was 523,000, and the molecular weight distribution (Mw / Mn) was 5.5.

Examples 1 and 2 Rubber content 13.2% by weight, average rubber particle diameter 0.59
μm, cumulative particle size distribution 5% value 0.75 μm, cumulative particle size distribution 95% value 0.29 μm, ratio of rubber particles having salami structure 96%, ratio of 20 or less included PS 94%, toluene-insoluble matter and rubber component Is 2.0, surface tension is 2
Rubber-modified polystyrene (resin-A1) 1 containing 0.05% by weight of 0.9 dyne / cm silicone oil
The copolymer-type antistatic agent obtained in the above Reference Example was blended in an amount shown in Table 1 with respect to 00 parts by weight, and pelletized by a melt extruder. The obtained pellet was formed into a flat plate of 100 mm × 100 mm × 3 mm by an injection molding machine, and the surface resistivity was measured after a predetermined humidity control. Further, the obtained flat plate was subjected to a water washing treatment, and after adjusting the humidity for a predetermined time, the surface resistivity was measured. Table 1 also shows the results of various physical property tests. The Izod impact value of the molded article of the rubber-modified polystyrene resin (resin-A1) used as the raw material was 1
5.0 kgfcm / cm, and gloss value was 102%.

Examples 3 and 4 100 parts by weight of the rubber-modified polystyrene used in Examples 1 and 2 were added with the same copolymer type antistatic agent as in Examples 1 and 2 and sodium alkyl sulfonate (SAS carbon number 12). ) Were blended in the proportions shown in Table 1 and pelletized by a melt extruder. Using the obtained pellets, Examples 1 and 2
Table 1 shows the results of evaluating various physical properties in the same manner as in Example 1.
Shown in

[0049]

[Table 1]

Comparative Examples 1 and 2 100 parts by weight of the rubber-modified polystyrene used in Examples 1 and 2 were mixed with the same copolymer type antistatic agent as in Examples 1 and 2 at the ratio shown in Table 1 and melted. It was pelletized by an extruder. Table 2 shows the results of evaluating various physical properties of the obtained pellets in the same manner as in Examples 1 and 2.

Comparative Example 3 Rubber content 10.0 wt%, average rubber particle diameter 1.0 μm
m, cumulative particle size distribution 5% value 1.5 μm, cumulative particle size distribution 95% value 0.6 μm, percentage of rubber particles having a salami structure 98%, percentage of 20 or less included PS 65%, toluene-insoluble matter and rubber component Is 2.2, surface tension is 20.9d
The same copolymer type antistatic agent as in Examples 1 and 2 is shown in Table 1 with respect to 100 parts by weight of rubber-modified polystyrene (resin-A2) to which 0.05% by weight of silicone oil of yne / cm is added. And pelletized by a melt extruder. Table 2 shows the results of evaluating various physical properties of the obtained pellets in the same manner as in Examples 1 and 2.

Comparative Example 4 Rubber content 12.8% by weight, average rubber particle diameter 0.43
μm, cumulative particle size distribution 5% value 0.82 μm, cumulative particle size distribution 95% value 0.15 μm, ratio of rubber particles having a salami structure 52%, ratio of 20 or less included PS 93%, toluene-insoluble matter and rubber component Is 2.3, surface tension is 2
Rubber-modified polystyrene (resin-A3) 1 containing 0.05% by weight of 0.9 dyne / cm silicone oil
With respect to 00 parts by weight, the same copolymer type antistatic agent as in Examples 1 and 2 was blended in the ratio shown in Table 2 and pelletized by a melt extruder. Table 2 shows the results of evaluating various physical properties of the obtained pellets in the same manner as in Examples 1 and 2.

Comparative Example 5 Rubber content 6% by weight, average rubber particle size 2.3 μm, cumulative particle size distribution 5% value 1.20 μm, cumulative particle size distribution 95
% Value 3.12 μm, ratio of rubber particles having salami structure 96%, ratio of 20 or less contained PS 50%, ratio of toluene-insoluble matter to rubber component 3.3, surface tension 20.9 dy
The same copolymer type antistatic agent as in Examples 1 to 3 is added to 100 parts by weight of rubber-modified polystyrene (resin-B) to which 0.05% by weight of ne / cm silicone oil is added, as shown in Table 2. And pelletized by a melt extruder. Table 2 shows the results of evaluating various physical properties of the obtained pellets in the same manner as in Examples 1 and 2.
The molded product of the impact-resistant polystyrene resin used as the raw material had an Izod impact value of 7.2 kgfcm / cm and a gloss value of 47%.

Comparative Example 6 A rubber-modified polystyrene having a core-shell structured rubber particle having a rubber content of 12% by weight and an average particle diameter of 0.3 μm, a rubber content of 10.6% by weight, an average particle diameter of 2.0 μm and a cumulative Particle size distribution 5% value 2.9 μm, cumulative particle size distribution 95% value 1.0 μm, ratio of rubber particles having salami structure 96
%, Ratio of less than 20 included ps 50%, ratio of toluene-insoluble matter to rubber component is 2.5, surface tension 20.9 dyne
/ Modified silicone polystyrene resin (resin-C) 100 in which rubber-modified polystyrene to which 0.05% by weight of silicone oil is added is blended at a ratio of 90 to 10, respectively.
To the parts by weight, the same copolymer type antistatic agent as in Examples 1 and 2 was blended in the ratio shown in Table 1, and pelletized by a melt extruder. Table 2 shows the results of evaluating various physical properties of the obtained pellets in the same manner as in Examples 1 and 2. The Izod impact value of the molded article of the rubber-modified polystyrene resin used for molding was 7.4 kgfcm / cm,
The gloss value was 101%.

[0055]

[Table 2]

As shown in Tables 1 and 2, when the amount of the antistatic agent added was less than 1.0 part by weight (Comparative Example 1), the surface resistance was high.
A sufficient antistatic effect cannot be obtained. On the other hand, when the amount of the antistatic agent is 10 parts by weight or more (Comparative Example 2), the impact resistance is inferior. From Example-1 and Comparative Examples-3 and 4, when the base resin is the resin A of the present invention, the surface resistivity is smaller by about one digit and the antistatic effect is obtained even when the amount of the antistatic agent is the same. Is improving. In addition, resin A1 has high gloss and has both surface properties and antistatic properties. Examples 1 and 2
In each of Comparative Examples 1 to 4, when the amount of the antistatic agent added increases, a streak-like flow mark is observed in the appearance. Therefore, SAS is added as shown in Examples 3 and 4. Thus, the appearance defect is eliminated, the surface resistivity is further reduced by about one digit, and the antistatic property is synergistically improved.

FIG. 1 is a transmission electron micrograph of the surface layer of the molded product obtained in Example 1, and FIG. 2 is a transmission electron micrograph of the surface layer of the molded product obtained in Example-4. In FIGS. 1 and 2, what looks like salami is a rubber component, and the dispersed particles which look like elongated stripes are antistatic agents. When the dispersed particles are relatively large and the aspect ratio is small, poor appearance is easily observed. However, by using the SAS together, the antistatic agent is finely dispersed in a streak form,
It has a feature that appearance performance and impact resistance are improved. In addition, since the antistatic agent is finely dispersed in a streak shape, the antistatic effect is improved with an increase in aspect ratio and efficient formation of conductive paths.

[0058]

According to the resin composition of the present invention, not only is it excellent in permanent antistatic properties and excellent in preventing dust from adhering to the surface of an injection-molded article, but also the base thermoplastic resin And a material for injection molding comprising a styrene-based resin composition having an excellent balance of properties in appearance performance without deteriorating the strength and surface gloss. For this reason, the injection molding material comprising the styrene resin composition of the present invention is extremely useful as a plastic material used for automobile interior parts and home electric appliances whose appearance is regarded as important.

[Brief description of the drawings]

FIG. 1 is a transmission electron micrograph of a surface layer of a molded article obtained in Example-1.

FIG. 2 is a transmission electron micrograph of a surface layer of a molded product obtained in Example-4.

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[Procedure amendment]

[Submission date] January 21, 1997

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] All figures

[Correction method] Change

[Correction contents]

FIG.

FIG. 2

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinji Inaba 3-35-1, Ida, Nakahara-ku, Kawasaki-shi, Kanagawa Nippon Steel Corporation Technology Development Division (72) Inventor Ikuo Yamaoka Nakahara-ku, Kawasaki-shi, Kanagawa 3-35-1, Ida Nippon Steel Corporation Technology Development Division

Claims (4)

[Claims] 1. A rubber-modified styrenic resin 100 comprising a rubbery polymer dispersed in a styrenic resin matrix.
Styrene based on 1 part by weight of a monomer unit having a quaternary ammonium base and 1 to 10 parts by weight of a copolymer composed of a vinyl or vinylidene monomer unit copolymerizable therewith In the resin composition, (1) the weight-average particle diameter of the dispersed particles of the rubber-like polymer in the rubber-modified styrene resin is in the range of 0.4 to 0.9 μm, and their weight-based cumulative particle size distribution 5% value is 1.0 μm or less, 95% value is 0.2 μm or more, and (2) the proportion of dispersed particles having a salami structure in the dispersed particles of all rubbery polymers is 80% by weight or more, In addition, the dispersion particles in which the number of particles of the aromatic vinyl polymer contained in all the rubber-like polymer dispersion particles is 20 or less are 70% or more of all the dispersion particles, and (3) the toluene-insoluble component And the ratio of the rubber component is 1.0 to 2.5 Permanent antistatic styrenic resin composition, characterized in that in circumference. 2. A copolymer comprising 20 to 80% by weight of a monomer unit having a quaternary ammonium group represented by the following formula (I), and a vinyl- or vinylidene-based monomer copolymerizable therewith. And the copolymer has a weight average molecular weight Mw of 200,000 to 1,000.
2. The permanent antistatic styrenic resin composition according to claim 1, wherein the styrene resin composition has a molecular weight distribution represented by a ratio of weight average molecular weight Mw to number average molecular weight Mn of 3 to 10. (Wherein, R ₁ is a monovalent group having a polymerizable carbon-carbon double bond, and R ₂ , R ₃ and R ₄ are hydrogen or C 1-9 which may have a substituent.) The alkyl group, X ^- represents a monovalent inorganic or organic acid group or a corresponding equivalent of an inorganic or organic acid.) 3. An alkyl sulfonate or an aromatic sulfonate in an amount of 0.3 parts by weight per 100 parts by weight of the styrene-based resin composition having a permanent antistatic property according to claim 1 or 2.
A permanent antistatic styrenic resin composition characterized by being blended with 10 to 10 parts by weight. 4. A molded article obtained by molding the permanent antistatic styrenic resin composition according to any one of claims 1 to 3, wherein the molded article has a surface layer portion from the molded article surface to a depth of 20 μm. The copolymer-type antistatic agent is dispersed in a resin forming a matrix as streak particles, and the weight average major axis of the streak particles is 0.5 to 100 μm in a cross section in the depth direction.
m, an average aspect ratio of 50 to 500.