KR20010036714A - Transparent thermoplastic resin composition having superior parting properties and method for preparing the same - Google Patents

Abstract

PURPOSE: A transparent thermoplastic resin composition having good releasing ability is provided for achieving excellent and balanced physical properties such as transparency, impact-resistance, chemical-resistance, workability and releasing property by adding metal salt of higher fatty acid and silicon oil as releasing agent. CONSTITUTION: A transparent thermoplastic resin composition having good releasing ability comprises monomer mixture composed of 8-25 weight parts of polybutadiene rubber latex, 40-70 weight parts of alkylester methacrylate or alkylester acrylate compounds, 15-30 weight parts of aromatic vinyl compound and 1-20 weight parts of vinyl cyanic compound; emulsifying agent, controlling agent of molecular weight, and polymerization initiator to proceed graft-polymerization. The composition further includes 0.001-1 weight parts of metal salt of higher fatty acid and 0.01-0.1 weight parts of silicon oil.

Description

Transparent thermoplastic resin excellent in mold release property and its manufacturing method {TRANSPARENT THERMOPLASTIC RESIN COMPOSITION HAVING SUPERIOR PARTING PROPERTIES AND METHOD FOR PREPARING THE SAME}

[Industrial use]

The present invention relates to a transparent thermoplastic resin composition excellent in releasability and a method for manufacturing the same, and more particularly, polybutadiene rubber latex graft copolymerization of methacrylic acid alkyl ester compound, aromatic vinyl compound, vinyl cyan compound and the like by emulsion polymerization The release property is imparted to the transparent ABS thermoplastic resin having excellent impact resistance, chemical resistance and processability.

[Prior art]

Recently, many studies have been conducted to give high functionality such as transparency to plastic materials. For example, researches that newly give transparency of materials, such as PCS transparent windows, microwave transparent windows, all-axis transparent windows, game machine housings, and office equipment transparent windows, are being intensively conducted. However, conventional acrylonitrile-butadiene-styrene (hereinafter referred to as ABS) copolymer resins used in these parts are excellent in impact resistance, chemical resistance, processability and surface gloss, but are opaque materials because of their properties. Materials that require transparency have limitations in use. In addition, the recent design improvements and product model differentiation is increasing the demand for the production of large injection moldings or injection molding of a thin and complex structure.

In response to these demands, the transparent resin manufacturing methods up to now have been difficult to produce a balanced resin in terms of rigidity, processability and releasability. The resins having impact resistance and chemical resistance are difficult to manufacture large injection molding products and complex injection molding products due to the lack of processability, and the release product lacks mold release cracking or deformed shape products are produced and whitening phenomenon appears.

In view of the problems of the prior art, an object of the present invention is to provide a transparent thermoplastic resin composition excellent in releasability while maintaining properties such as transparency, impact resistance, chemical resistance, and workability, and a method of manufacturing the same.

Another object of the present invention is to provide a transparent thermoplastic resin composition showing a balanced physical property of transparency, impact resistance, chemical resistance, processability and release property, and a method of manufacturing the same.

[Means for solving the problem]

The present invention to achieve the above object,

a) 8 to 25 parts by weight of polybutadiene rubber latex;

b) methacrylic acid alkyl ester compounds or acrylic acid alkyl esters

40 to 70 parts by weight of the compound;

c) 15 to 30 parts by weight of an aromatic vinyl compound; And

d) 1 to 20 parts by weight of the vinyl cyan compound

In the thermoplastic transparent resin composition prepared by graft copolymerization of the monomer mixture of the emulsion polymerization, including an emulsifier, a molecular weight regulator, and a polymerization initiator by emulsion polymerization,

e) 0.001 to 1 part by weight of a metal salt of higher fatty acid; And

f) 0.01 to 0.1 parts by weight of silicone oil

It provides a transparent thermoplastic resin composition excellent in the releasability further comprising.

In addition, the present invention

a) 8 to 25 parts by weight of polybutadiene rubber latex;

b) methacrylic acid alkyl ester compound or acrylic acid alkyl ester compound

40 to 70 parts by weight;

c) 15 to 30 parts by weight of an aromatic vinyl compound;

d) 1 to 20 parts by weight of the vinyl cyan compound;

e) 0.001 to 1 part by weight of a metal salt of higher fatty acid;

f) 0.01 to 0.1 parts by weight of silicone oil; And

g) emulsifiers, molecular weight modifiers, and polymerization initiators as additives

Graft copolymerization by emulsion polymerization, including a transparent thermoplastic resin

Manufacturing steps

It provides a method for producing a transparent thermoplastic resin composition excellent in releasability comprising a.

In addition, the present invention

a) 8 to 25 parts by weight of polybutadiene rubber latex;

Ii) Methacrylic acid alkyl ester compound or acrylic acid alkyl ester

40 to 70 parts by weight of the compound;

Iii) 15 to 30 parts by weight of an aromatic vinyl compound

Iii) 1 to 20 parts by weight of a vinyl cyan compound

Monomer mixtures, including emulsifiers, molecular weight modifiers, and polymerization initiators.

Graft copolymerization by emulsion polymerization to prepare a transparent thermoplastic resin

step; And

b) to the transparent thermoplastic resin prepared in step a)

Iii) 0.001 to 1 part by weight of a metal salt of higher fatty acid; And

Iii) 0.01 to 0.1 parts by weight of silicone oil

Adding

It also provides a method for producing a transparent thermoplastic resin composition excellent in releasability comprising a.

Hereinafter, the present invention will be described in detail.

[Action]

In the present invention, when a transparent thermoplastic ABS resin is grafted by emulsion polymerization, a metal salt of a higher fatty acid and silicone oil are added as a releasing agent to maintain excellent properties such as transparency, impact resistance, chemical resistance, and processability. will be. In particular, the addition of silicone oil having excellent release properties only increases the release property and impact strength of the transparent resin, but also increases the haze value. As a supplement to this drawback, metal salts of higher fatty acids added together with the haze of the transparent resin Compensation for dysplasia while preventing increase in value.

Therefore, the present invention is a methacrylic acid alkyl ester compound, aromatic with conjugated diene rubber latex mixture having a particle size of 1600 to 3500 kPa, gel content of 70 to 95%, swelling index of 12 to 30 and monomers to be grafted thereto. It applies to the transparent thermoplastic resin manufactured by graft-polymerizing the composition containing a vinyl compound and a vinyl cyan compound by an emulsion polymerization method.

The refractive index of the monomer mixture used at this time absolutely affects the transparency, and this refractive index is controlled by the amount of the monomer used and the mixing ratio. That is, in order to have transparency, the refractive index of the conjugated diene compound used as a seed for the graft and the refractive index of the entire component to be grafted should be about the same, so the amount of the monomer used and the mixing ratio are very important. The refractive index of each component used at this time is 1.518 for butadiene, 1.49 for methyl methacrylate, 1.59 for styrene, and 1.518 for acrylonitrile.

The graft addition method of each component in the grafting polymerization reaction may use a method of batch administration of each component and a method of continuously (sequentially) administering a total amount or a part of the present invention. It takes a complex form.

When grafting, the metal salt of higher fatty acids and silicone oil are added together with the monomer to improve the releasability. The metal salt and silicone oil of the higher fatty acid used at this time may be administered with a monomer or a method of batch administration after polymerization. In addition, when administering with the monomer, a method of batch administration with each raw material at the time of graft and a method of administering continuously (sequential) by mixing with a portion of the monomer may be used.

Hereinafter, the present invention will be described in detail.

A) Polybutadiene rubber latex manufacturing process

80 to 100 parts by weight of 1,3-butadiene, 20 parts by weight of 1,2-butadiene, 1 to 4 parts by weight of emulsifier, 0.2 to 1.5 parts by weight of polymerization initiator, 0.5 parts by weight of electrolyte, 0.1 to 0.5 parts by weight of molecular weight regulator, ions 75 parts by weight of exchange water was collectively administered, followed by emulsion polymerization at 65 to 85 ° C. for 25 to 50 hours to obtain an average particle diameter of 2500 to 5000 mm 3, a gel content of 60 to 95%, and a swelling index of 12 to 40 polybutadiene rubber. Prepare latex.

The emulsifier is preferably alkyl aryl sulfonate, alkali methyl alkyl sulfate, sulfonated alkyl ester, soap of fatty acid, alkali salt of rosin acid, and the like, and can be used alone or in mixture of two or more thereof.

As the polymerization initiator, a water-soluble persulfate or a peroxy compound can be used, and an oxidation-reduction system can also be used. The water-soluble persulfate is preferably sodium and potassium persulfate, and the fat-soluble polymerization initiator is cumene hydroperoxide, diisopropyl benzenehydroperoxide, azobis isobutylnitrile, tertiary butyl hydroperoxide or paramethane hydroperoxide. , Benzoyl peroxide and the like are preferred, and can be used alone or in mixture of two or more thereof.

The electrolyte may be KCl, NaCl, KHCO ₃ , NaHCO ₃ , K ₂ CO 3, Na ₂ CO 3, KHSO ₃ , NaHSO ₃ , K ₄ P ₂ O ₇ , K ₃ PO ₄ , Na ₃ PO ₄ , K ₂ HPO ₄ , It is possible to use Na ₂ HPO ₄ and the like alone or in mixture of two or more thereof.

Mercaptans are mainly used as said molecular weight regulator.

The emulsion polymerization temperature is very important for adjusting the gel content and swelling index of the rubber latex, and the selection of the initiator should also be considered.

B) graft copolymer manufacturing process

8 to 15 parts by weight of the conjugated diene rubber latex prepared by the above method, 40 to 70 parts by weight of an alkyl methacrylate compound or an acrylic acid alkyl ester compound, 15 to 30 parts by weight of an aromatic vinyl compound, 1 to 20 parts by weight of a vinyl cyan compound, Graft copolymerization includes 0.2 to 0.6 parts by weight of an emulsifier, 0.2 to 0.6 parts by weight of a molecular weight regulator, and 0.05 to 0.3 parts by weight of a polymerization initiator.

The mixing ratio of the monomers is very important for obtaining a resin having transparency, and the refractive index varies depending on the mixing ratio. That is, the refractive index of the conjugated diene rubber latex used as the seed and the total refractive index of the compound grafted thereon should be similar, and the difference between the refractive indexes of the conjugated diene rubber latex and the entire compound grafted thereto is not less than 0.005. Back side is not suitable for the present invention.

The polymerization temperature is suitable 65 ~ 80 ℃ and the polymerization time is suitable 4 ~ 7 hours.

The emulsifiers used in the polymerization reaction are alkylaryl sulfonates, alkali methylalkyl sulfates, sulfonated alkyl esters, fatty acid soaps, alkali salts of rosin acids, and the like, and these may be used alone or as a mixture of two or more thereof.

As the molecular weight regulator, tertiary dodecyl mercaptan is mainly used.

Polymerization initiators include peroxides such as cumene hydroperoxide, diisopropylbenzenehydro peroxide, persulfate, sodium formaldehyde sulfoxylate, sodium ethylenediamine tetraacetate, ferrous sulfate, dextrose, sodium pyrrolate, and Oxidation-reduction catalyst systems made of a mixture with a reducing agent such as sodium sulfate and the like can be used.

In addition, 0.001 to 1 part by weight of the metal salt of the higher fatty acid and 0.01 to 0.1 part by weight of the silicone oil are added to improve the releasability while maintaining transparency. The addition method may be a method of continuous or batch administration with a monomer or batch administration after polymerization.

Zinc-stearate, magnesium-stearate, etc. are used as a metal salt of a higher fatty acid, and the quantity uses 0.001-1 weight part. The use of 0.001 part by weight or less lowers the transparency, and the use of 1 part by weight or more lowers the transparency and lowers the impact strength.

The silicone oil has a refractive index of 1.35 to 1.45 as a structural unit represented, and may be represented by the following Chemical Formula 1.

[Formula 1]

(CH ₃ ) ₃ SiO [SiO (CH ₃ ) ₂ ] _n Si (CH ₃ ) ₃

Where

n is an integer of 1 or more.

The viscosity range of the silicone oil used is 10 to 100 centi-stokes (cs) at 25 ° C., more preferably 20 to 50 cs. Although the amount of use is 0.01 to 0.1 parts by weight, using less than 0.01 results in poor releasability, and using 0.1 or more results in poor transparency.

The polymerization conversion rate of the latex obtained after the completion of the polymerization was 99% or more. An antioxidant and a stabilizer were administered to the latex to coagulate with an aqueous calcium chloride solution at a temperature of 80 ° C. or higher, followed by dehydration and drying to obtain a powder. After adding the antioxidant and stabilizer to the obtained powder, pellets were prepared using a twin screw extruder at 200 to 230 ° C., and the pellets were injected again to measure their physical properties.

The present invention will be described in more detail with reference to the following examples and comparative examples. However, an Example is for illustrating this invention and is not limited only to these.

EXAMPLE

Example 1

a) Manufacture of conjugated diene rubber latex

(Manufacture of small diameter rubber latex)

110 parts by weight of ion-exchanged water, 99 parts by weight of 1,3-butadiene as monomer, 1 part by weight of styrene, 1.2 parts by weight of potassium rosin salt as emulsifier, 1.5 parts by weight of potassium oleate salt, into a nitrogen-substituted polymerization reactor (autoclave) 0.1 parts by weight of sodium carbonate (Na ₂ CO ₃ ) as electrolyte, 0.5 parts by weight of potassium hydrogen carbonate (KHCO ₃ ), and 0.3 parts by weight of tertiary dodecyl mercaptan (TDDM) as the molecular weight modifier were added and the reaction temperature was raised to 55 ° C. 0.3 parts by weight of potassium persulfate as an initiator was used to initiate the reaction and reacted for 10 hours, and then 0.05 parts by weight of tertiary dodecyl mercaptan was further added again to react at 65 ° C. for 8 hours, and then the reaction was terminated. And the obtained rubber latex was analyzed as follows.

The gel content and the swelling index were solidified by diluting the rubber latex with dilute acid or metal salt, washed, dried in a vacuum oven at 60 ° C. for 24 hours, and then chopped into pieces of rubber with scissors. After storage in a dark room at room temperature for 48 hours, separated into sol and gel, and the gel content and swelling index were measured according to the following equations (1) and (2), respectively.

[Equation 1]

[Equation 2]

The particle diameter was measured using HPL (Nicomp 370 HPL) by the dynamic laser light scattering method.

The rubber latex obtained at this time had a particle diameter of 1000 GPa, a gel content of 90%, and a swelling index of 18.

(Small Diameter Rubber Latex Fusion)

100 parts by weight of the small-diameter rubber latex prepared above was added to the reactor, the stirring speed was adjusted to 10 rpm, and then the temperature was adjusted to 30 ° C., and then 2.5 parts by weight of 7% acetic acid aqueous solution was gradually added for 1 hour, and then the stirring was stopped. After the mixture was allowed to stand for 30 minutes, a small diameter rubber latex was fused to prepare a conjugated diene rubber latex. This was analyzed by rubber latex prepared by the fusion process.

The rubber latex obtained at this time had a particle diameter of 2300 mm 3, a gel content of 90%, and a swelling index of 17.

b) graft copolymer preparation

100 parts by weight of ion-exchanged water, 0.2 parts by weight of sodium oleate emulsifier, 18.72 parts by weight of methyl methacrylate, 7.28 parts by weight of styrene, 3.33 weights of acrylonitrile Parts, tertiary dodecyl mercaptan 0.2 part by weight, sodium pyrophosphate 0.048 part by weight, dextorose 0.012 part by weight, ferrous sulfide 0.001 part by weight, cumene hydroperoxide 0.04 part by weight at 50 ℃ and collectively the reaction temperature The emulsion polymerization was carried out while increasing to 73 ° C. over 2 hours.

And 60 parts by weight of ion-exchanged water, 0.4 parts by weight of sodium oleate, 37.44 parts by weight of methyl methacrylate, 14.56 parts by weight of styrene, 6.67 parts by weight of acrylonitrile, 0.25 parts by weight of tertiary dodecyl mercaptan, 0.048 parts of sodium pyrophosphate Parts by weight, dextrose 0.012 parts by weight, ferrous sulfide 0.001 parts by weight, cumene hydroperoxide 0.10 parts by weight and magnesium-stearate 0.01 parts by weight, silicone oil (Dow corning 200 Fluid; 20 cs; Index of Refraction 1.4) After 0.02 parts by weight of the mixed emulsion solution was continuously administered for 4 hours, the temperature was further raised to 76 ° C, and aged for 1 hour, and the reaction was terminated.

At this time, the polymerization conversion rate was 99.5% and the solid coagulation content was 0.1%. The latex is then coagulated with an aqueous calcium chloride solution, washed and a powder is obtained.

0.1 parts by weight of lubricant and 0.2 parts by weight of antioxidant were administered to 100 parts by weight of the graft copolymer prepared in the form of pellets using a twin screw extruder at a cylinder temperature of 210 ° C. The pellets were injected into the pellets to prepare specimens, and the physical properties thereof were measured by the following methods.

Izod Impact Strength: ASTM D256

Haze Value: ASTM D1003

Release property: In an injection molding machine using a 3 ounce cup mold, the release property was measured by measuring the pressure applied to the eject pin when the injection product was taken out. The lower the measured value, the better the releasability.

Example 2

160 parts by weight of ion-exchanged water, 0.6 parts by weight of sodium oleate emulsifier, 56.16 parts by weight of methyl methacrylate, 21.84 parts by weight of styrene in a nitrogen-substituted polymerization reactor in 12 parts by weight of the conjugated diene rubber latex prepared in Example a). , 10.0 parts by weight of acrylonitrile, 0.45 parts by weight of tertiary dodecyl mercaptan, 0.096 part by weight of sodium pyrophosphate, 0.024 part by weight of dextrose, 0.002 part by weight of ferrous sulfide, 0.14 part by weight of cumene hydroperoxide, magnesium- 0.01 parts by weight of stearate and 0.02 parts by weight of silicone oil (Dow Corning 200 Fluid; 20 cs; refractive index 1.4) were collectively administered at 50 ° C., and the reaction temperature was increased to 73 ° C. over 2 hours. I was.

At this time, the polymerization conversion rate was 99.5% and the solid coagulation content was 0.1%. The latex is then coagulated with an aqueous calcium chloride solution, washed and a powder is obtained.

0.1 parts by weight of lubricant and 0.2 parts by weight of antioxidant were administered to 100 parts by weight of the graft copolymer prepared in the form of pellets using a twin screw extruder at a cylinder temperature of 210 ° C. The pellets were injected into the pellets to prepare specimens, and the physical properties thereof were measured by the method of Example 1 and shown in Table 2.

Example 3

The same procedure as in Example 1 was carried out, but the magnesium-stearate and the silicone oil were collectively added after the graft polymerization.

Example 4

The same procedure as in Example 1 was carried out except that the amounts of magnesium stearate and silicone oil were changed to the compositions shown in Table 1.

Comparative Examples 1 to 4

The same method as in Example 1 was carried out, but the composition ratio of magnesium-stearate and silicon oil was changed to the composition shown in Table 1 and added.

Dosage and Method of Magnesium-Stearate and Silicone Oil division Magnesium-Stearate Silicone oil Input method Example 1 0.1 0.02 Continuous injection at graft Example 2 0.1 0.02 Bulk injection at graft Example 3 0.1 0.02 Batch injection after polymerization Example 4 0.05 0.05 Continuous injection at graft Comparative Example 1 0 0 Continuous injection at graft Comparative Example 2 0.05 0 Continuous injection at graft Comparative Example 3 0 0.2 Continuous injection at graft Comparative Example 4 2 0.1 Continuous injection at graft

Property comparison division Impact strength Haze Release (millibars) Example 1 11.5 2.5 2500 Example 2 10.0 2.5 2400 Example 3 11.5 3.0 2500 Example 4 11.8 2.9 2500 Comparative Example 1 10.0 2.2 4700 Comparative Example 2 10.0 2.5 4100 Comparative Example 3 12.5 6.0 2600 Comparative Example 4 12.0 5.5 2300

The transparent thermoplastic resin composition of the present invention exhibits balanced physical properties in transparency, impact resistance, processability, and the like, and is particularly excellent in releasability, and is advantageous for producing large injection molding products, thin injection molding products, and the like.

Claims (14)

a) 8 to 25 parts by weight of polybutadiene rubber latex; b) methacrylic acid alkyl ester compounds or acrylic acid alkyl esters 40 to 70 parts by weight of the compound; c) 15 to 30 parts by weight of an aromatic vinyl compound; And d) 1 to 20 parts by weight of the vinyl cyan compound In the thermoplastic transparent resin composition prepared by graft copolymerization of the monomer mixture of the emulsion polymerization, including an emulsifier, a molecular weight regulator, and a polymerization initiator by emulsion polymerization, e) 0.001 to 1 part by weight of a metal salt of higher fatty acid; And f) 0.01 to 0.1 parts by weight of silicone oil Transparent thermoplastic resin composition excellent in releasability comprising a further. The method of claim 1, The transparent thermoplastic resin composition excellent in releasability whose metal salt of the higher fatty acid of said e) is zinc-stearate or magnesium-stearate. The method of claim 1, The silicone oil of f) is a compound represented by the following Chemical Formula 1, the refractive index is 1.35 to 1.45, the transparent thermoplastic resin composition excellent in releasability of 10 to 100 centistokes (cs) at 25 ℃: [Formula 1] (CH ₃ ) ₃ SiO [SiO (CH ₃ ) ₂ ] _n Si (CH ₃ ) ₃ Wherein n is an integer of 1 or more. The method of claim 3, wherein A transparent thermoplastic resin composition having excellent release property of the silicone oil having a viscosity of 20 to 50 cs at 25 ° C. a) 8 to 25 parts by weight of polybutadiene rubber latex; b) methacrylic acid alkyl ester compound or acrylic acid alkyl ester compound 40 to 70 parts by weight; c) 15 to 30 parts by weight of an aromatic vinyl compound; d) 1 to 20 parts by weight of the vinyl cyan compound; e) 0.001 to 1 part by weight of a metal salt of higher fatty acid; f) 0.01 to 0.1 parts by weight of silicone oil; And g) emulsifiers, molecular weight modifiers, and polymerization initiators as additives Graft copolymerization by emulsion polymerization, including a transparent thermoplastic resin Manufacturing steps Method for producing a transparent thermoplastic resin composition excellent in releasability comprising a. The method of claim 5, Method for producing a transparent thermoplastic resin composition excellent in the releasability of the metal salt of the higher fatty acid of e) and f) silicone oil is continuously mixed with the monomer at the time of graft. The method of claim 5, Method for producing a transparent thermoplastic resin composition excellent in the releasability of the metal salt of the higher fatty acid of e) and f) silicone oil is mixed and added to the monomer at the time of graft. The method according to any one of claims 5 to 7, A method for producing a transparent thermoplastic resin composition excellent in releasability wherein the metal salt of the higher fatty acid of e) is zinc-stearate or magnesium-stearate. The method according to any one of claims 5 to 7, The silicone oil of f) is a compound represented by the following formula (1), the refractive index is 1.35 to 1.45, the viscosity of 10 to 100 centistokes (cs) at 25 ℃ excellent method for producing a transparent thermoplastic resin composition: [Formula 1] (CH ₃ ) ₃ SiO [SiO (CH ₃ ) ₂ ] _n Si (CH ₃ ) ₃ Wherein n is an integer of 1 or more. The method of claim 9, Method for producing a transparent thermoplastic resin composition excellent in releasability of the viscosity of the silicone oil 20 to 50 cs at 25 ℃. a) 8 to 25 parts by weight of polybutadiene rubber latex; Ii) Methacrylic acid alkyl ester compound or acrylic acid alkyl ester 40 to 70 parts by weight of the compound; Iii) 15 to 30 parts by weight of an aromatic vinyl compound; And Iii) 1 to 20 parts by weight of a vinyl cyan compound Monomer mixtures, including emulsifiers, molecular weight modifiers, and polymerization initiators. Graft copolymerization by emulsion polymerization to prepare a transparent thermoplastic resin; And b) to the transparent thermoplastic resin prepared in step a) Iii) 0.001 to 1 part by weight of a metal salt of higher fatty acid; And Iii) 0.01 to 0.1 parts by weight of silicone oil Adding Method for producing a transparent thermoplastic resin composition excellent in releasability comprising a. The method of claim 11, The method for producing a transparent thermoplastic resin composition having excellent releasability, wherein the metal salt of the higher fatty acid of step b) is zinc-stearate or magnesium-stearate. The method of claim 11, The silicone oil of step b) is a compound represented by the following formula (1), the refractive index is 1.35 to 1.45, the viscosity of 25 to 10 centistokes (cs) excellent in releasability method of producing a transparent thermoplastic resin composition: [Formula 1] (CH ₃ ) ₃ SiO [SiO (CH ₃ ) ₂ ] _n Si (CH ₃ ) ₃ Wherein n is an integer of 1 or more. The method of claim 13, Method for producing a transparent thermoplastic resin composition excellent in releasability of the viscosity of the silicone oil 20 to 50 cs at 25 ℃.