JP2000256523A - Styrenic resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a styrenic resin composition which has excellent dust resistance and excellent appearance. SOLUTION: This styrenic resin composition comprises (A) a styrenic resin, (B) the hydrogenated product of a styrene-conjugated diene block copolymer or a modified product thereof, (C) the ionomer of an ethylene-unsaturated carboxylic acid copolymer and (D) a polyhydroxy compound. Therein, the components A, B and C are added in amounts of 40-94 pts.wt., 1-30 pts.wt. and 5-40 pts.wt., respectively, per 100 pts.wt. of the total amount of the components A, B and C, and the component D is added in an amount of 0.1-30 pts.wt. based on the component C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a styrene resin composition having excellent dust resistance and appearance.

[0002]

2. Description of the Related Art In general, polystyrene has good moldability and dimensional accuracy, and has a beautiful appearance.
Widely used in household goods. In addition, impact-resistant polystyrene and ABS resin have excellent impact resistance, rigidity, moldability, and good appearance, and are used in automobile interior and exterior parts, home appliances, OA equipment, housing equipment, leisure goods, miscellaneous goods, etc. Widely used. However, such a styrene resin generally has a large electric resistance and is easily charged by friction, and thus has a drawback that dust easily adheres to the surface of a molded product. For this reason, various antistatic formulations have been studied.

[0003] For example, Japanese Patent Application Laid-Open No. Hei 7-2 proposed by the present applicant.
According to JP-A-16178 and JP-A-8-134295, an alkali metal ionomer of an ethylene / unsaturated carboxylic acid copolymer, especially a potassium ionomer,
By compounding a polyhydroxy compound such as polyethylene glycol or glycerin with a styrene resin,
It discloses that a molded article having excellent antistatic performance and good dustproof properties can be obtained. However, such a formulation had a drawback that the excellent appearance, which is an excellent feature of the styrene-based resin, was easily impaired. In other words, when molding at the molding temperature of a normal styrene resin, the molded article may be colored, and when the molding temperature is too low to avoid coloring, there is a problem that the molded article surface is not smooth. .

[0004]

SUMMARY OF THE INVENTION Accordingly, the present inventors
Formulations that improve the appearance of styrene-based resins, ionomers, and polyhydroxy compound-containing systems without impairing the excellent dust resistance were studied. As a result, they have found that this object can be achieved by further blending a hydrogenated product of the styrene / conjugated diene block copolymer or a modified product thereof with such a blending system. Therefore, an object of the present invention is to provide a styrenic resin composition having good appearance and excellent dustproofness.

[0005]

That is, the present invention provides a styrene resin (A), a hydrogenated product of a styrene / conjugated diene block copolymer or a modified product thereof (B), and an ethylene / unsaturated carboxylic acid copolymer. Consisting of an alkali metal ionomer (C) and a polyhydroxy compound (D),
(A), (B), (C) per 100 parts by weight of the total,
(A) 40 to 94 parts by weight, (B) 1 to 30 parts by weight,
The present invention relates to a styrenic resin composition wherein (C) is blended in a proportion of 5 to 40 parts by weight and (D) is blended in a proportion of 0.1 to 30 wt% of (C).

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The styrenic resin in the present invention is a thermoplastic resin composed of a homopolymer or a copolymer of styrene.
S resin and ABS resin can be exemplified. Here, polystyrene includes general-purpose polystyrene and heat-resistant polystyrene obtained by various production methods such as a suspension polymerization method and an emulsion polymerization method, butadiene rubber, styrene.
It is a general term for impact-resistant polystyrene obtained by graft-polymerizing styrene onto rubber components such as butadiene copolymer rubber and ethylene-propylene copolymer rubber.

The ABS resin is a general term for rubber-reinforced styrene polymer resins synthesized by various production methods such as a blending method, a grafting method or a graft blending method, and includes butadiene rubber, styrene / butadiene copolymer rubber, and ethylene. A typical example is a rubber component such as propylene copolymer rubber, which is obtained by grafting styrene and another monomer such as acrylonitrile, methyl methacrylate, α-methylstyrene, ethylenebisimide or phenylmaleimide.

The styrene / conjugated diene block copolymer in the hydrogenated styrene / conjugated diene block copolymer or its modified product (B) is a block containing at least one styrene polymer unit and at least one conjugated diene polymer unit. Copolymer, as long as there is such a polymer unit,
A random copolymer unit of styrene and a conjugated diene may be included. As typical examples thereof, polystyrene / polybutadiene / polystyrene triblock copolymer and polystyrene / polyisoprene / polystyrene triblock copolymer can be exemplified. The hydrogenated product of such a block copolymer is obtained by hydrogenating a conjugated diene polymerized unit of a raw material block copolymer,
The most typical ones are a polystyrene / poly (ethylene / butene) / polystyrene block copolymer and polystyrene / poly (ethylene / propylene) generally called SEBS and SEPS in which the above triblock copolymer is hydrogenated. -It is in the form of a polystyrene block copolymer. In the hydrogenated product of such a block copolymer, the number of polystyrene polymerized units is 10 to 10.
Preferred are those having 50% by weight, particularly 20 to 40% by weight, and the conjugated diene polymer block having a hydrogenated unit of 50 to 90% by weight, particularly 60 to 80% by weight.

In the present invention, a hydrogenated product of such a block copolymer can be used as it is,
In consideration of the effect of addition, it is preferable to use those which have been modified so as to further impart a functional group thereto.
One example of such modification is graft modification with an unsaturated carboxylic acid or anhydride thereof. Specific examples include acrylic acid, methacrylic acid, unsaturated carboxylic acids such as fumaric acid, maleic anhydride, itaconic anhydride, and graft modification with unsaturated dicarboxylic anhydrides such as norbornene dicarboxylic anhydride. it can. Most preferred is a graft modification with maleic anhydride. Such an acid-modified product has an acid value of 0.1 to 20 mg CH ₃ ONa / g, particularly 2 to 10 m
It is preferred to use those of gCH ₃ ONa / g. The melt flow rate under a load of 5 kg at 200 ° C. is 0.1 to 200 g / 10 min, particularly 1 to 100 g /
It is preferable to use one for 10 minutes.

The ethylene / unsaturated carboxylic acid copolymer serving as the base polymer of the alkali metal ionomer of the ethylene / unsaturated carboxylic acid copolymer used as the component (C) of the present invention is ethylene, unsaturated carboxylic acid, And another polar monomer.
Here, examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, fumaric acid, maleic anhydride, monomethyl maleate, monoethyl maleate and the like, and acrylic acid or methacrylic acid is particularly preferable. In addition, as a polar monomer that can be a copolymer component,
Vinyl acetate, vinyl esters such as vinyl pyropionate, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-hexyl acrylate, isooctyl acrylate, methyl methacrylate, maleic acid Unsaturated carboxylic acid esters such as dimethyl and diethyl maleate, carbon monoxide, etc., and particularly unsaturated carboxylic acid esters are suitable copolymerization components. Such an ethylene / unsaturated carboxylic acid copolymer can be obtained by radically copolymerizing ethylene, an unsaturated carboxylic acid, and optionally another polar monomer at high temperature and high pressure.

As the alkali metal ionomer (C), those having excellent non-charging properties are used. For this purpose, the unsaturated carboxylic acid content of the ethylene / unsaturated carboxylic acid copolymer serving as a base polymer, alkali metal Type,
It is necessary to appropriately select the degree of neutralization and the like. The use of potassium ionomer is most preferable in consideration of non-charging property and economic efficiency. Here, as the potassium ionomer, if the acid content of the ethylene / unsaturated carboxylic acid copolymer serving as the base polymer is too small or the degree of neutralization is too small, a composition having good non-charging properties can be obtained. Not easy. Thus, for example, the degree of neutralization of an ethylene / unsaturated carboxylic acid copolymer having an unsaturated carboxylic acid content of 10 to 30% by weight, preferably 15 to 25% by weight with potassium ions is 60% or more, preferably 70% by weight or more. It is preferred to use the potassium ionomer of

As a compound having a lower amount of potassium ions and exhibiting high non-charging properties, there are potassium ionomers of two or more ethylene / unsaturated carboxylic acid copolymers having different average acid contents. For example, two or more copolymers having an average acid content of 10 to 30% by weight, preferably 11 to 20% by weight, wherein the difference in acid content between the highest acid content and the lowest acid content is 1% by weight or more, The mixed ionomer preferably has a degree of neutralization of the ethylene / unsaturated carboxylic acid copolymer different from 2 to 20% by weight with potassium ions of 60% or more, preferably 70% or more. Considering various properties, the use of such a mixed ionomer is more preferable.

The above-mentioned ethylene / unsaturated carboxylic acid copolymer serving as the base polymer of the potassium ionomer contains the above-mentioned polar monomer in an amount of 40% by weight or less, preferably 30% by weight or less. It may be. Considering the processability and miscibility with other components, the potassium ionomer has a temperature of 190 ° C., 216 ° C.
The melt flow rate at 0 g load is 0.1 to 10
It is preferable to use one having 0 g / 10 min, especially 0.1 to 50 g / 10 min.

The polyhydroxy compound (D) is a compound having two or more alcoholic hydroxyl groups, and specifically, a polyoxyalkylene glycol such as polyethylene glycol, polypropylene glycol, polyoxyethylene / polyoxypropylene glycol having various molecular weights. ,
Examples thereof include polyhydric alcohols such as glycerin, hexanetriol, pentaerythritol and sorbitol, and their ethylene oxide adducts and adducts of polyamines and alkylene oxides.

In the present invention, a styrene resin (A),
The usage ratio of the hydrogenated product of the styrene / conjugated diene block copolymer or its modified product (B) and the ionomer (C) of the ethylene / unsaturated carboxylic acid copolymer is such that the total amount of the three is 100 parts by weight. When (A) is 40 to 9
0 parts by weight, preferably 45 to 85 parts by weight,
30 parts by weight, preferably 5 to 25 parts by weight;
It is 40 parts by weight, preferably 10 to 35 parts by weight. If the use ratio of the component (A) is less than the above range, it becomes difficult to exhibit excellent properties of the styrene resin. If the amount of the component (B) is too small,
While it is difficult to sufficiently exert the effect of improving the appearance, if the amount exceeds the above range, it becomes too flexible, which is not preferable. If the amount of the component (C) is less than the above range, it is difficult to impart sufficient dustproofness,
Use of the composition in an amount larger than the above range is not preferred because the composition easily absorbs moisture.

On the other hand, the polyhydroxy compound (D) is an important component for improving the non-charging property of a potassium ionomer under low humidity, and the amount of the polyhydroxy compound (D) used is such that the potassium ionomer is used in order to impart sufficient non-charging property. Is from 0.1 to 30% by weight, preferably from 1 to 20% by weight, more preferably from 2 to 1% by weight, based on (C).
The proportion is 5% by weight. As described above, the polyhydroxy compound is used together with the potassium ionomer as described above, so that even if it is blended in a considerable amount, it is not incorporated into the composition and does not bleed out, but if it is blended beyond the above range, it bleeds out. Is not preferred.

The components (A), (B), (C), and (D) can be simultaneously compounded, or can be sequentially compounded in any order. Generally, in consideration of the miscibility of the component (D), it is desirable to mix (C) and (D) in advance. The compounding can be performed, for example, by using a melt kneading apparatus such as an extruder and melt-mixing each component. Molding from the composition of the present invention may be carried out immediately after melt mixing, or after melt mixing, once pelletized, it can be molded by another molding machine.

The composition of the present invention can also contain various additives according to the purpose. Such additives include, for example, antioxidants, light stabilizers, ultraviolet absorbers, pigments, dyes, slip agents, crosslinking agents, crosslinking aids, foaming agents, foaming aids, tackifiers, inorganic fillers, Fiber reinforced materials and the like can be exemplified.

[0019]

The present invention will be specifically described below with reference to examples. In addition, the raw material used in the Example and the comparative example and the measuring method of the physical property of the obtained composition are shown below.

1. Raw materials (1) Styrene resin HIPS resin (Nippon Polystyrene HIPS H
(640N) (2) Acid-modified styrene / butadiene block copolymer hydrogenated product (SEBS) Tuftec M1962 manufactured by Asahi Kasei Corporation (polystyrene unit / ethylene / butylene unit = 30/70, MF)
R60g / 10min (200 ° C, 5kg)) (3) Hydrogenated styrene-butadiene block copolymer (SEBS) Toughtech H1031 manufactured by Asahi Kasei Kogyo Co., Ltd. (polystyrene unit / ethylene / butylene unit = 30/70, MF)
R 80 g / 10 min (200 ° C., 5 kg)) (4) Ionomer / glycerin mixture Potassium ionomer of ethylene / methacrylic acid copolymer having a methacrylic acid content of 12.5% by weight (neutralization degree 82%,
Potassium content 1.2 mol / kg ionomer, MFR
0.4 g / 10 min) 1 glycerin manufactured by Kanto Chemical Co., Ltd.
0% by weight

1. Physical property measurement method (1) Appearance of molded article A T-shaped molded article was processed and evaluated for color tone, reproducibility of a right-angled portion, and surface smoothness, and determined as follows. Color tone: The presence or absence of yellowing due to burning or the like was examined. Reproducibility of right angle portion: Judgment was made based on whether or not the angle was a right angle as in the case of the base. Good: There was reproducibility. Bad: rounded corners. Surface smoothness: The presence or absence of irregularities on the molded product surface was confirmed. Good: No surface irregularities were observed. Poor: Asperities were seen overall. (2) Surface resistivity A test piece was measured at 23 ° C and a relative humidity of 30%, 40%, 50%, and 6%.
After aging at 0% for 24 hours, the surface resistivity was measured with a high resistivity meter (HIRESTA-IP) manufactured by Mitsubishi Chemical Corporation.

Example 1 A HIPS resin, an SEBS acid-modified product and an ionomer / glycerin mixture were mixed at a mixing ratio of 60:10:30 by weight, and then a resin temperature of 19 using a 40 mmφ extruder.
A T-shaped molded product was processed at 0 ° C. The appearance of the obtained molded product was good. The obtained molded product was dried overnight at 100 ° C. and 10 torr using a vacuum dryer, and then pressed at 180 ° C. to form a 1 mm thick sheet. Table 1 shows the measurement results of the surface resistivity of the test pieces at relative humidity of 30%, 40%, 50%, and 60%. The surface resistivity of each of the obtained molded articles had a small humidity dependence and was a value sufficiently small to exhibit non-charging properties.

Example 2 In Example 1, the weight ratio of the HIPS resin, the modified SEBS acid and the ionomer / glycerin mixture was 55: 1.
The same procedure as in Example 1 was carried out except that 5:30 was used. The appearance of the obtained molded product was good. Further, as shown in Table 1, the surface resistivity was small in humidity dependency and small enough to exhibit non-charging property.

Example 3 In Example 1, the weight ratio of the HIPS resin, the modified SEBS acid and the ionomer / glycerin mixture was set to 50: 2.
The procedure was performed in the same manner as in Example 1 except that the time was changed to 0:30. The appearance of the obtained molded product was good. Further, as shown in Table 1, the surface resistivity was small in humidity dependency and small enough to exhibit non-charging property.

Example 4 The procedure of Example 2 was repeated, except that the SEBS acid-modified product was replaced with SEBS. The appearance of the obtained molded product was good. Further, as shown in Table 1, the surface resistivity was small in humidity dependency and small enough to exhibit non-charging property.

[0026]

[Table 1]

Comparative Example 1 A molded article was processed in the same manner as in Example 1 except that the SEBS acid-modified product was not added. The surface of the molded product became shark skin-like. A pressure-formed test piece of the molded product was prepared, and its surface resistivity was measured in the same manner. As shown in Table 2, the results were all small in humidity dependency and small enough to exhibit non-charging properties.

Comparative Example 2 A molded article was processed from HIPS resin alone in the same manner as in Example 1. The appearance of the molded article was good. A pressure-formed test piece of the molded product was prepared, and its surface resistivity was measured in the same manner. As shown in Table 2, the results did not show any non-chargeability.

[0029]

[Table 2]

[0030]

The molded article obtained from the composition of the present invention by various molding methods such as extrusion molding, injection molding, hollow molding, compression molding, etc., has excellent appearance while having excellent characteristics inherent to styrene resins. In addition, it is excellent in non-charging properties, and the deterioration of the antistatic effect is small even under low humidity. In addition, the antistatic property is excellent, and since there is no stickiness on the surface of the molded article, the dustproof property is excellent. Taking advantage of such features, it can be widely used, for example, for interior and exterior materials of automobiles, office automation equipment, home electric appliance parts or storage and storage cases thereof, stationery, daily necessities, and the like.

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[Procedure amendment]

[Submission date] April 7, 1999 (1999.4.7)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction contents]

In the present invention, a styrene resin (A),
The usage ratio of the hydrogenated product of the styrene / conjugated diene block copolymer or its modified product (B) and the ionomer (C) of the ethylene / unsaturated carboxylic acid copolymer is such that the total amount of the three is 100 parts by weight. When (A) is 40 to 9
4 parts by weight, preferably 45 to 85 parts by weight,
30 parts by weight, preferably 5 to 25 parts by weight;
It is 40 parts by weight, preferably 10 to 35 parts by weight. If the use ratio of the component (A) is less than the above range, it becomes difficult to exhibit excellent properties of the styrene resin. If the amount of the component (B) is too small,
While it is difficult to sufficiently exert the effect of improving the appearance, if the amount exceeds the above range, it becomes too flexible, which is not preferable. If the amount of the component (C) is less than the above range, it is difficult to impart sufficient dustproofness,
Use of the composition in an amount larger than the above range is not preferred because the composition easily absorbs moisture.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction contents]

1. Physical property measurement method (1) A molded product was processed into a deformed extruded product with a T-shaped cross-sectional appearance,
The reproducibility of the right-angled portion and the smoothness of the surface were evaluated and determined as follows. Color tone: The presence or absence of yellowing due to burning or the like was examined. Reproducibility of right angle portion: Judgment was made based on whether or not the angle was a right angle as in the case of the base. Good: There was reproducibility. Bad: rounded corners. Surface smoothness: The presence or absence of irregularities on the molded product surface was confirmed. Good: No surface irregularities were observed. Poor: Asperities were seen overall. (2) Surface resistivity A test piece was heated at 23 ° C. and a relative humidity of 30%, 40%, 50%, and 6%.
After aging at 0% for 24 hours, the surface resistivity was measured with a high resistivity meter (HIRESTA-IP) manufactured by Mitsubishi Chemical Corporation.

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Claims (1)

[Claims] 1. A styrene resin (A), a hydrogenated product of a styrene / conjugated diene block copolymer or a modified product thereof (B), an alkali metal ionomer (C) of an ethylene / unsaturated carboxylic acid copolymer, and a polystyrene. It consists of a hydroxy compound (D), and the total of (A), (B) and (C) is 100
(A) is 40 to 94 parts by weight and (B) is 1 part by weight.
A styrene-based resin composition comprising (C) in an amount of 0.1 to 30 parts by weight, (C) in an amount of 5 to 40 parts by weight, and (D) in an amount of 0.1 to 30% by weight of (C).