JP2781335B2 - Rubber-modified styrenic resin composition and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber-modified styrenic resin composition and a method for producing the same, and more particularly, to a product obtained by reusing the resin molded product having excellent surface impact strength. The present invention also relates to an impact-resistant rubber-modified polystyrene resin composition having good strength and physical properties and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, in order to improve the impact resistance of a styrene-based resin, polystyrene and a rubber-like polymer are kneaded, or the rubber-like polymer is dissolved in a styrene-based monomer and grafted. By performing a polymerization reaction or the like, a mixed state of the rubbery graft polymer (dispersed phase) and polystyrene (continuous matrix phase) is obtained. Since the rubber-modified styrene resin described above has relatively good impact resistance, it is also referred to as impact-resistant styrene resin (hereinafter abbreviated as HIPS). In general, as a method for measuring the impact strength of the impact-resistant styrene-based resin thus obtained, an Izod impact strength test is performed using a test piece obtained by compression molding or injection molding. Although the above Izod impact strength is a kind of mechanical property of styrene resin, surface impact strength is also a very important evaluation parameter for products. In addition to emphasizing, the surface impact strength is similarly requested and paid attention.

[0003] However, conventional techniques such as Japanese Patent Laid-Open No.
-172948, JP-A-57-170949 and JP-A-57-187346
In Japanese Patent Application Laid-Open No. H11-163, as a means for increasing the impact resistance of HIPS, a method of adding a small amount of an organic polysiloxane to a styrene-based resin has been proposed, but sufficient improvement in surface impact strength cannot be obtained.

Japanese Patent Publication No. Sho 55-30525 discloses a HIPS having a good surface impact strength by adding a special butadiene rubber (containing 15 to 35% of 1,2-vinyl bond) to styrene to carry out a polymerization reaction. Although a method for obtaining the HIPS is disclosed, the HIPS produced by this method has a drawback that the rubber graft ratio is as high as 350% or more and the flowability is poor, so that the processability is poor, and its use is limited. .

Further, US Pat. Nos. 3,954,976, 4,294,937 and 4,451,612 include HI by continuous bulk or solution polymerization.
In the process of producing PS, hue, in order to obtain a resin having excellent thermal stability, usually when charging a styrene monomer,
Phenolic or phosphorus antioxidants, for example, 2,6-
A method is described in which di-tert-butyl-4-methylphenol, octadecyl-3- (3,5-di-tert-butyl-4-hydroxy-phenyl) propionate, tri (nonylphenyl) phosphite and the like are added in small amounts. However, although this processing method provides a resin excellent in hue, it does not improve HIPS surface impact strength at all.

[0006] On the other hand, when a mass production of HIPS products is actually performed by those skilled in the art, inevitably some defective products and scraps are generated, and in order to reduce costs, the defective products and scraps are usually crushed again. Regenerate and mold.
However, the impact resistance of the recovered resin is originally reduced due to the influence of the heat history and the frictional shear stress. Although it is possible to supplement the Izod impact strength to some extent by adding an antioxidant, it is less effective in improving the surface impact strength. Therefore, at present, HI
The PS resin product has a disadvantage that the surface impact strength is still insufficient.

[0007]

Accordingly, the present invention provides good surface impact strength and physical properties not only for resin products but also for products reclaimed by recovering the composition from defective products or scraps. An object of the present invention is to provide an impact-resistant polystyrene resin composition and a method for producing the same.

[0008]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have made further studies on the relationship between the rubber particle size distribution and the specific compound, and as a result, it has been found that the dispersion of dispersed particles in a styrene resin is improved. By adding a thiodipropionate-based compound and an organic polysiloxane at a specific ratio to a styrene-based resin obtained by dispersing a rubber-like polymer so that the dispersion coefficient becomes 0.8 or more, the resin has a high Izod impact strength. It has been found that the surface impact strength can be further improved not only for the product but also for a recycled product as well as the product, and the present invention has been completed.

That is, the present invention relates to (A) a styrene resin 98
~ 80 parts by weight and 2 to 20 parts by weight of a rubbery polymer dispersed in the styrene resin, and the dispersion particles of the rubbery polymer calculated by the following formula (I) by a laser light scattering method 100 parts by weight of a rubber-modified styrenic resin having a particle size distribution coefficient of 0.8 or more, and (B ₁ ) a thiodipropionate compound 0.
02 to 1.0 parts by weight, and (B ₂ ) organopolysiloxane 0.002 to 0.
The present invention provides a rubber-modified styrenic resin composition comprising 8 parts by weight.

[0010]

(Equation 1)

In the method for producing the rubber-modified styrenic resin composition, 2 to 20 parts by weight of a rubbery polymer is dissolved in 98 to 80 parts by weight of a styrene monomer and the polymerization reaction is carried out at 90 to 250 ° C. And after the conversion of the styrene-based monomer reaches 55% by weight or more, the method for producing a rubber-modified styrene-based resin composition in which volatile components are removed. 0.02 to 1.0 part by weight of (B ₁ ) thiodipropionate-based compound in any of the above polymerization reaction steps, and before the phase inversion where the rubbery polymer becomes particles, based on 100 parts by weight of to the to the total of 100 parts by weight of the rubbery polymer and the styrene monomer, characterized by adding (B ₂₎ organopolysiloxanes 0.002 to 0.8 parts by weight.

The rubber-modified styrenic resin according to the present invention comprises:
It is obtained by dissolving a rubber-like polymer in a vinyl-based aromatic monomer and performing a polymerization reaction by a polymerization method such as bulk, solution, or solution-suspension or bulk-suspension two-stage system.

In the present invention, the vinyl aromatic monomer constituting the rubber-modified styrenic resin (A) includes, for example,
Styrene, o-methylstyrene, m-methylstyrene,
alkyl-substituted styrenes such as p-methylstyrene, 2,4-dimethylstyrene, ethylstyrene, p-tert-butylstyrene, α-methylstyrene, α-alkyl-substituted styrenes such as α-methyl-p-methylstyrene, Bromostyrene, dibromostyrene, 2,4,6-tribromostyrene and the like can be mentioned, and one or more of these are used. Other copolymerizable monomers may be added to the styrene monomer. In this case, other copolymerizable monomers include, for example, unsaturated nitriles (eg, acrylonitrile), acrylates (eg, methyl methacrylate, butyl acrylate), acrylic acids, maleic anhydride, maleimides (eg, N -Phenylmaleimide) and the like.

The type of the rubber polymer used in the present invention is not particularly limited. Rubber used in conventional HIPS resins can be used. For example, natural rubber, polybutadiene, polyisoprene, styrene-butadiene rubber-like polymer, styrene-polyisoprene rubber-like polymer, butyl rubber, ethylene-propylene rubber, and the like, and one or more of these may be used. it can. Among them, polybutadiene rubber includes low cis polybutadiene and high cis polybutadiene.

In the present invention, the rubber content in 100 parts by weight of the HIPS resin is 2 to 20 parts by weight, particularly preferably 3 to 15 parts by weight. When the amount of the rubber is less than 2 parts by weight, the surface impact strength is insufficient, and when the amount exceeds 20 parts by weight,
The fluidity is reduced, and the tensile strength may be reduced.

The step of producing the rubber-modified styrenic resin (A) is as follows. That is, by dissolving about 2 to 20 parts by weight of a rubbery polymer in 98 to 80 parts by weight of a styrene monomer and polymerizing the rubbery polymer, the rubbery graft polymer in the form of particles and grafted with a styrene polymer is obtained. And a styrene resin matrix continuous phase. The average particle size of the rubbery graft polymer is in the range of 0.5 to 10 μm, and 0.6 to 5 μm.
The range of μm is preferable, and the range of 0.7 to 3.0 μm is more preferable. Average particle size of rubber particles (D _ave )
Is obtained by measuring the number (ni) of particles corresponding to each particle diameter (Di) based on a laser light scattering method (LASER scattering), and then obtaining the average equation called Sauter Mean Diamter. is there.

[0017]

(Equation 2)

The particle size distribution coefficient of the graft rubber particles in the HIPS resin (A) of the present invention is 0.8 or more, preferably larger than 0.9, and more preferably 0.9 to 2.8. When the particle size distribution coefficient is less than 0.8, the surface impact strength of the one obtained by collecting and reusing the HIPS resin is inferior, and when the particle size distribution coefficient exceeds 2.8, the tensile strength of the HIPS resin decreases. Become.

The particle size distribution coefficient is further adjusted by adjusting the stirring speed of the polymerization reaction, the amount and timing of adding the thiodipropionate compound (B ₁ ) and the organic polysiloxane (B ₂ ), the reaction temperature and the like. It can be obtained by:

In the present invention, the particle size distribution coefficient of the rubber-like polymer particles is determined by the laser light scattering method (LASER scattering).
And its definition is shown as the following formula (I).

[0021]

(Equation 3)

[Where D (V, 0.1) is the cumulative distribution curve from small particle size to large particle size, where the horizontal axis is the particle diameter of rubber and the vertical axis is the cumulative weight% of the rubber. D (V, 0.5) is the cumulative distribution curve from small particle size to large particle size with D (V, 0.5) being the horizontal axis of the rubber particle diameter and the vertical axis being the cumulative weight% of the particles. , D (V, 0.9) is the rubber particle diameter on the horizontal axis and the cumulative weight% of the particle is on the vertical axis, from small particle diameter to large particle diameter. In the cumulative distribution curve, the cumulative weight% is 90%
Is the rubber particle size corresponding to ].

In the laser light scattering measurement method, a sample of 0.1 g was vibrated until it was sufficiently dissolved in 10 ml of methyl ethyl ketone, and then the focal point was set to 100 mm by a laser light scattering device.
As a result, a particle size distribution map is obtained, or a sample of 1.0 g is vibrated until sufficiently dissolved in 10 ml of methyl ethyl ketone, and then a laser light scattering device is used.
A particle size distribution diagram is obtained by performing the measurement with the focal point set to 45 mm. From this, the particle size distribution coefficient of the rubbery polymer particles is determined from the above equation. That is, if the numerical value of the particle size distribution coefficient is small, the particle size distribution becomes narrow, and if it is large, the particle size distribution becomes wide.

Specific examples of the thiodipropionate compound (B ₁ ) used in the present invention include distearyl thiodipropionate (referred to as DSTDP), dilauryl thiodipropionate, and ditridecyl thiopionate. Dipropionate, dimyristylthiodipropionate and the like can be mentioned. The amount used is 0.02 to 1.0 part by weight, preferably 0.04 to 0.4 part by weight, based on 100 parts by weight of the HIPS resin (A). The amount of the thiodipropionate-based compound (B ₁ ) added is 0.
When the amount is less than 02 parts by weight, the effect of improving the surface impact strength is small, and when the amount exceeds 1.0 part by weight,
Not only is the surface impact strength inferior, but also the rubber particle size distribution coefficient
If it is 3.0 or more, the tensile strength is further reduced.

The organic polysiloxane (B) used in the present invention
₂ ) is represented by the following structural formula.

[0026]

Embedded image

[Where m and n are integers, and R _{1 to} R ₄ are an alkyl or aryl group. ] Dynamic viscosity at 25 ° C. of the organopolysiloxane (B ₂₎ is 10 to 10,000 centistokes, especially 20 to 2,000 centistokes, more preferably. The amount of the organic polysiloxane (B ₂ ) to be added is in the range of 0.002 to 0.8 parts by weight, preferably 0.04 to 0.3 parts by weight, based on 100 parts by weight of the HIPS resin (A). When the amount of the organic polysiloxane (B ₂ ) is less than 0.002 parts by weight,
If the surface impact strength of the resin is inferior, and if the addition amount exceeds 0.8 parts by weight, the tensile strength of the HIPS resin decreases and the secondary processing of the resin molded product (for example, chemical adhesion, printability, Paintability).

The timing of adding the organic polysiloxane (B ₂ ) to the present invention is as follows during the polymerization reaction of the HIPS resin.
It must be added before the phase inversion of the rubbery polymer into particles. Preferably, the rubber component in the polymerization reaction has not yet completed phase inversion, and the conversion of the styrene monomer is 12%.
Before reaching the weight%. Here, “phase inversion” means that at the initial stage of polymerization of a mixed solution of rubber and styrene monomer, the rubber phase exists in a continuous phase, but the conversion of styrene monomer is Gradually increases, and as the reaction system is agitated, the rubber component is finally surrounded by the styrene-based monomer and its polymer, and becomes a dispersed particle state (discontinuous phase). , A phenomenon in which a styrene monomer and a polymer thereof are reversed to a continuous phase. In the present invention,
In order to significantly improve the surface impact strength of the resin, the thiodipropionate compound (B ₁ ) is added during the polymerization reaction step, and the organic polysiloxane (B ₂ ) is added before the phase inversion of the polymerization reaction. Must be added. Also, if necessary
The reaction rate and the graft state of the rubber can be appropriately adjusted, and the particle size distribution coefficient of the rubber can be controlled by appropriate stirring. If either the thiodipropionate-based compound (B ₁ ) or the organic polysiloxane (B ₂ ) is missing, sufficient surface impact strength cannot be obtained.

The thiodipropionate compound (B ₁ ) and the organic polysiloxane (B ₂ ) used in the present invention can each be charged into a reaction tank by a metering pump. In addition, (B ₁ ) or (B
₂ ) may be added to a reaction monomer and / or a solution comprising a solvent and a rubbery polymer, and then charged into a reaction tank. In particular, in order to obtain good surface impact strength, the addition time of the organic polysiloxane (B ₂ ) must be performed before the phase inversion of the polymerization reaction. Therefore, the method of adding the organic polysiloxane (B ₂ ) must be specially considered. For example, when a plug flow type reaction vessel is used as a phase inversion zone, a charged mixture obtained by mixing (B ₂ ) with a monomer and / or a solvent and rubber is added to the reaction vessel. It may be added (the timing of addition is referred to as the conversion of the monomer being 0% by weight), or may be added to the reaction zone where the conversion of the monomer reaches a predetermined value. on the other hand,
When using a complete mixing type reaction tank as the phase inversion zone, (B
₂ ) The monomer and / or solvent and a mixture prepared by mixing the rubber in a rubber must be added to the reaction vessel (the timing of the addition is referred to as the conversion of the monomer being 0% by weight). .

In the method for producing the HIPS resin of the present invention, the polymerization reaction can be carried out by a polymerization method such as bulk, solution, or solution-suspension or bulk-suspension. Preferably, bulk or solution polymerization is used. I do. The polymerization temperature is 90-25
0 ° C is preferable, and particularly preferably 95 to 210 ° C. The reaction tank used in the present invention is not limited. For example, either a completely mixed or plug-type reactor or a combination thereof may be used, or several reactors may be used in parallel or in series. Further, the reaction tank may be equipped with a stirrer. When a stirrer is attached, the stirring speed is 5 to 55 rpm
In particular, 8-45 rpm is more preferable. Incidentally, when charging the reactants, or during the progress of the reaction, if necessary, a molecular weight modifier, a polymerization initiator, an antioxidant, a plasticizer,
A lubricant, a solvent and the like may be added. After the polymerization reaction reached phase inversion, the conversion of the styrenic monomer was
%, Preferably 70% by weight or more. Thereafter, the polymer solution was sent to a preheater,
Heat to 300 ° C and discharge to a vacuum degassing tank to remove unreacted residual monomers, solvents and other volatiles. or,
The recovered solvent, monomer and the like are used by charging them to a reaction tank at an appropriate ratio. The residual volatile matter in the polymer obtained by the degassing process is set to 1% by weight or less, and usually extruded continuously by a gear pump to produce a granular resin.

As the molecular weight modifier applied to the present invention,
n-dodecyl mercaptan, α-methylstyrene dimer, t-dodecyl mercaptan, 1-phenylbutyl-
Examples include 2-fluorene, dipentene, carbon tetrachloride and the like, mercaptans, terpenes, halogenated hydrocarbons and the like.

Examples of the polymerization initiator applicable to the present invention include peroxyketals such as 1,1-bis (t-butylperoxy) cyclohexane, dicumyl peroxide and di-t-butyl peroxide. Dialkyl peroxides, diacyl peroxides such as dibenzoyl peroxide, peroxy dicarbonates such as dimyristyl peroxy dicarbonate, peroxy esters such as t-butyl peroxy isopropyl carbonate, ketone peroxides such as cyclohexanone peroxide. Examples thereof include oxides and hydroperoxides such as p-mentha hydroperoxide. The amount of the polymerization initiator is usually 0.6% by weight or less.

The plasticizer used in the present invention includes mineral oil, polybutene and the like. Examples of the lubricant used include stearic acid, zinc stearate, calcium stearate, stearylamide, N, N'-ethylene-bis (stearylamide) and the like. Antioxidants include 2,6-di-t-butyl-4-methylphenol, octadecyl-3- (3,5-di-t-butyl-4-
Examples include phenol compounds such as (hydroxy-phenyl) propionate and phosphorus compounds such as tris (nonylphenyl) phosphite and tri (2,4-di-t-butylphenyl) phosphite. Examples of the inert solvent include ethylbenzene, toluene, xylene, methylethylketone, benzene, isopropylbenzene, and the like, and the amount of addition can be up to 40% by weight as needed.

Further, in the HIPS resin of the present invention,
If necessary, lubricants, antioxidants, plasticizers, flame retardants, light stabilizers, coloring agents, glass fibers, inorganic fillers, etc. may be added. Other polymers such as PPO (polyphenylene oxide resin) ), Nylon-11, nylon-12,
Nylon-6, PC (polycarbonate resin), ABS
You may use together with resin, AS resin, PE (polyester resin), PP (polypropylene resin), etc.

[0035]

EXAMPLES The present invention will be described below in detail with reference to examples, but the scope of the present invention is not limited to these examples.

Example 1 The formulation of this example is shown below. (Components) (Amount) Styrene 83.0 parts by weight Ethylbenzene 10.0 parts by weight Polybutadiene 6.0 parts by weight DSTDP 0.2 parts by weight Polydimethylsiloxane 0.004 parts by weight Polymerization initiator (Trigonox D-E50) 0.02 parts by weight (However, Trigonox D-E50 is 2 parts by weight) , 2-di (t-butylperoxy) butane). The above formulation was stirred at a flow rate of 40 l / hr in a first reaction vessel equipped with a stirrer (the reaction vessel had a volume of 100 liters, a temperature in the range of 100 to 120 ° C, and a stirring speed of
40 rpm. ). Phase inversion occurred when the conversion of the styrene monomer reached about 14% by weight. The conversion at the outlet of the first reactor is almost 22% by weight,
After that, it is sent to the subsequent reaction tank to carry out the polymerization reaction, the polymerization temperature is controlled in the range of 125 to 220 ° C., and after the conversion of the polymer reaches about 80% by weight, the polymer solution is cooled. It was sent to a degassing tank to remove volatile components, and then a resin pump was produced from a die using a gear pump.

The physical properties of the obtained pellets were measured by the following methods. Izod impact strength: ASTM D-256 Tensile strength: ASTM D-638 Particle size distribution coefficient: Laser light scattering method Surface impact strength: Measured by a falling ball impact test of ASTM D-3763.

Surface Impact Strength of Recovered / Recycled Product: A HIPS resin pellet was repeatedly extruded twice with a twin screw extruder, then injected to form a test piece, and the surface impact strength of the test piece was measured.

Example 2 In Example 2, pellets were produced and tested in the same manner as in Example 1. The timing of adding polydimethylsiloxane and DSTDP to the reaction tank was such that the styrene conversion was 4% by weight. , And the amounts of addition were respectively changed to 0.05 parts by weight of DSTDP and 0.25 parts by weight of polydimethylsiloxane.

Example 3 The time when polydimethylsiloxane and DSTDP were added to the reaction tank was determined when the styrene conversion rate was 8%.
When the weight reached%, the amount of DSTDP was changed to 0.6 part by weight and the amount of polydimethylsiloxane was changed to 0.5 part by weight, and pellets were produced and tested in the same manner as in Example 1.

(Comparative Example 1) The timing at which polydimethylsiloxane and DSTDP were added to the reaction tank was determined when the styrene conversion rate was 10%.
When the weight reached%, the amount of DSTDP was changed to 1.2 parts by weight and the amount of polydimethylsiloxane was changed to 0.1 parts by weight. In addition, pellets were produced and tested in the same manner as in Example 1.

(Comparative Example 2-1) The time when polydimethylsiloxane and DSTDP were added to the reaction tank was determined when the styrene conversion reached 80% by weight and the amount of DSTDP added was changed.
Pellets were produced and tested in the same manner as in Example 1, except that 0.4 parts by weight and the amount of polydimethylsiloxane added were changed to 0 parts by weight.

(Comparative Example 2-2) The amount of DSTDP added was 0
Pellets were produced and tested in the same manner as in Comparative Example 2-1 except that the amount by weight of polydimethylpolysiloxane was changed to 1.2 parts by weight.

Example 4 The prescription of this example is as shown below.

(Component) (Amount) Styrene 83.0 parts by weight Ethylbenzene 8.0 parts by weight Polybutadiene 8.0 parts by weight DSTDP 0.15 parts by weight Polydimethylsiloxane 0.4 parts by weight Polymerization initiator (Tx 29A) 0.01 parts by weight (where Tx 29A is 1,5 parts by weight) 1-t-butylperoxy-3,3,5
-Trimethylcyclohexane. ) The above formulation is continuously fed into a first reactor with a stirrer at a flow rate of 36 l / hr (the reactor has a volume of 100 l, a temperature in the range of 105-130 ° C and a stirring speed of 30 rpm). Was charged. Phase inversion occurred when the conversion of the styrene monomer reached about 17% by weight. The conversion at the outlet of the first reactor is about 28
Wt.%, And then send it to the subsequent reactor to carry out the polymerization reaction, while controlling the polymerization temperature in the range of 135-220 ° C., and after the conversion of the polymer reaches 87 wt. The polymer solution was sent to a degassing tank to remove volatile components. Next, pellets were manufactured and tested in the same manner as in Example 1.

(Example 5) The time when polydimethylsiloxane and DSTDP were added to the reaction tank was determined when the styrene conversion rate was 10%.
When the amount of DSTDP reached 0.4% by weight, the amount of DSTDP was changed to 0.4 part by weight and the amount of polydimethylsiloxane was changed to 0.1 part by weight.

Example 6 DSTDP was added to the reactor when the styrene conversion reached 55% by weight.
The addition amount of STDP was 0.2 parts by weight, the addition amount of polydimethylsiloxane was 0.2 parts by weight, and the stirring speed of the first reaction tank was 30 rpm.
In addition to the above, pellets were produced and tested in the same manner as in Example 1.

(Comparative Example 3) The time when polydimethylsiloxane and DSTDP were added to the reaction vessel was set at a styrene conversion rate of 50.
In addition, when the weight of the pellets was reached, the amount of polydimethylsiloxane added was changed to 0.004 parts by weight, the amount of ethylbenzene used was changed to 10 parts by weight, and the stirring speed of the reaction tank was changed to 45 rpm. And tested.

Comparative Example 4 Pellets were produced and tested in the same manner as in Example 4 except that the amount of DSTDP was changed to 0 parts by weight and the amount of polydimethylsiloxane was changed to 0.4 parts by weight.

Comparative Example 5 Pellets were produced in the same manner as in Example 4 except that the component of DSTDP was changed to 0.15 part by weight of trisnonylphenyl phosphite (abbreviated as TNPP) and the added amount of polydimethylsiloxane was changed to 0.6 part by weight. And tested.

[0051]

[Table 1]

[0052]

[Table 2]

Continued on the front page (51) Int.Cl. ⁶ identification code FI C08L 83:04) (58) Investigated field (Int.Cl. ⁶ , DB name) C08L 51 / 04,83 / 04-83/12 C08K 5 / 36,5 / 54 C08F 279/00-279/06 CA (STN) REGISTRY (STN)

Claims (5)

(57) [Claims] 1. A method comprising: (A) 98 to 80 parts by weight of a styrene-based resin and 2 to 20 parts by weight of a rubbery polymer dispersed in the styrene-based resin. The calculated particle size distribution coefficient of the dispersed particles of the rubbery polymer is
100 parts by weight of a rubber-modified styrenic resin showing 0.8 or more,
(B ₁₎ thio and thiodipropionate compound 0.02 to 1.0 parts by weight, (B ₂₎ rubber-modified styrene resin composition characterized by comprising the organopolysiloxane from 0.002 to 0.8 parts by weight. (Equation 1) 2. The rubbery polymer has a particle size distribution coefficient of 0.9.
The rubber-modified styrenic resin composition according to claim 1, wherein the composition ranges from 2.8 to 2.8. 3. The rubber-modified styrene resin composition according to claim 1, wherein the thiodipropionate compound is distearyl thiodipropionate. 4. A rubbery polymer of 2 to 20 parts by weight is dissolved in 98 to 80 parts by weight of a styrene monomer, and a polymerization reaction is carried out at 90 to 250 ° C. to give a conversion of the styrene monomer of 55 parts by weight. % Or more, the volatile component is removed to produce a rubber-modified styrenic resin composition, wherein (B ₁ ) Thiodipropionate compound 0.02
~ 1.0 parts by weight added in any of the above polymerization reaction steps, and before the phase inversion of the rubbery polymer into particles,
Production of a rubber-modified styrenic resin composition characterized by adding 0.002 to 0.8 parts by weight of (B ₂ ) an organic polysiloxane to 100 parts by weight of the total of the rubbery polymer and the styrenic monomer. Method. 5. The rubber-modified styrene resin composition according to claim 4, wherein the (B ₂ ) organic polysiloxane is added before the conversion of the styrene monomer reaches 12% by weight. Method of manufacturing a product.