KR100733927B1 - Impact strength modifiers for polyvinyl chloride and preparation method thereof - Google Patents

Abstract

The present invention relates to a rubber latex having a multilayered structure, wherein the rubber latex has a refractive index greater than that of the rubber latex of the outer layer; Graft copolymers prepared from the rubber latex; PVC resin blend comprising the graft copolymer; And it provides a method for producing the rubber latex. PVC resin blends comprising graft copolymers comprising rubber latex of the present invention have improved color properties and low temperature impact strength compared to conventional PVC resins.

Impact resistance, whitening resistance, impact modifier, PVC resin, core-shell structure, refractive index, color characteristics, low temperature impact strength, rubber latex, graft copolymer

Description

Impact strength modifiers for polyvinyl chloride and preparation method

The present invention relates to an impact modifier for polyvinyl chloride (hereinafter referred to as "PVC") resin and a method for producing the same, and more particularly to an alkyl (meth) acrylate-conjugated diene used as an impact modifier for PVC resins. A graft copolymer of a monomer-ethylenically unsaturated aromatic compound (hereinafter referred to as " MBS system ") and a method for producing the same.

PVC resin is a polymer containing more than 50% of vinyl chloride (Vinyl chloride) has a disadvantage of being very weak against impact, and methods for compensating for this disadvantage have long been studied. To improve the impact resistance, there is a method of using a graft polymer obtained by grafting a monomer such as styrene, methyl methacrylate or acrylonitrile to a rubber latex based on butadiene as an impact modifier of PVC resin. Although the method has an impact reinforcing effect of PVC resin, there is a problem in that the transparency of the product is lowered and it is accompanied by whitening when forming a sheet.

The physical properties of the MBS graft copolymer are known to be affected by the content and polymerization method of each monomer to be grafted, the content and particle size of the rubber latex (latex) used as a substrate. In order to improve the impact strength, it is a general method to increase the content and particle size of the rubber latex used as the substrate, but when such rubber latex is included in the PVC resin, light scattering effect is increased by increasing the particle diameter of the graft copolymer particles for impact modifier. As a result, the transparency of the PVC resin is reduced and the difference in refractive index between the PVC resin and the graft copolymer particles for the impact modifier is large, or when the deformation of the MBS graft copolymer for the impact modifier and the PVC resin is weak, If the micro-void) is easily generated, there is a problem that the whitening degree may be increased and the impact strength may not be good.

To date, there have been many studies on rubber particle content and size, graft polymerization method and graft composition in order to prepare graft copolymer particles having excellent impact resistance, transparency and whitening resistance. In particular, when the use of rubber latex is limited depending on the use, it is well known that the content of the grafted monomer and the graft polymerization method have a great influence on the transparency and impact strength of the product.

MBS-based graft copolymers are generally used as additives to improve impact resistance, whitening resistance, processability, and optical properties of PVC resins. MBS-based graft copolymers include, for example, styrene-butadiene rubber latex. The rubber latex of the same conjugated diene-based monomer-ethylenically unsaturated aromatic compound is prepared by grafting alkyl (meth) acrylate and ethylenically unsaturated aromatic compound by emulsion polymerization.

Factors that influence the physical properties of the MBS graft copolymer include the content of each monomer to be grafted and the polymerization method, and the most important factor is the physical properties of the rubber latex used as the substrate of the MBS graft copolymer. In particular, it is known that the size, content of the rubber latex and the composition ratio of the constituent monomers directly affect the optical and physical properties of the PVC resin.

In particular, US Pat. No. 4,352,910 to Katto et al. Describes the impact strength and whitening resistance of a rubber latex by controlling the glass transition temperature of a rubber latex using a multi-step polymerization method in the preparation of MBS-based graft copolymers. A method for producing a well-balanced MBS-based graft copolymer is disclosed.

However, the method which can improve the color characteristic and low temperature impact strength of PVC resin using MBS type graft copolymer is not demonstrated in the prior art.

Accordingly, an object of the present invention is to provide a graft copolymer and a method for manufacturing the same, which can enhance the color properties and low temperature impact strength of PVC resin.

The first technical problem to be achieved by the present invention is to provide a rubber latex used in the manufacture of the impact reinforcing graft copolymer of the PVC resin.

The second technical problem to be achieved by the present invention is to provide a graft copolymer comprising the rubber latex.

The third technical problem to be achieved by the present invention is to provide a PVC resin blend comprising the graft copolymer.

The fourth technical problem to be achieved by the present invention is to provide a method for producing the rubber latex.

The above and other objects of the present invention can be achieved by the configuration of the present invention described below.

The present invention to achieve the first technical problem,

A rubber latex having a multilayer structure provides a rubber latex in which the refractive index of the inner rubber latex is larger than that of the outer rubber latex.

In order to achieve the second technical problem, the present invention graft emulsified 5 to 50% by weight of at least one monomer selected from the group consisting of alkyl (meth) acrylate and ethylene unsaturated aromatic compounds in 50 to 95% by weight of the rubber latex. It provides a graft copolymer, characterized in that prepared by polymerization.

In order to achieve the third technical problem the present invention provides a PVC resin blend consisting of 1 to 20% by weight of the graft copolymer and 80 to 99% by weight of PVC resin.

The present invention to achieve the fourth technical problem

(1) preparing an inner layer rubber latex by first emulsion-polymerizing 25 to 75% by weight of a monomer mixture of a conjugated diene monomer, an ethylenically unsaturated aromatic compound and a crosslinking agent; And

(2) provides a method for producing a rubber latex comprising the step of emulsion polymerization of the residual monomer mixture 25 to 75% by weight in the rubber latex of the inner layer to produce a rubber latex of the outer layer.

PVC resin prepared using the graft copolymer according to the present invention as an impact modifier has an advantage of excellent impact strength, particularly low temperature impact strength at -10 ° C or less and excellent color characteristics.

Hereinafter, the present invention will be described in more detail.

First, the rubber latex according to the present invention; Graft copolymer prepared using the rubber latex; It will be described below with respect to the PVC resin blend comprising the graft copolymer.

MEANS TO SOLVE THE PROBLEM In the manufacture of the rubber latex used as the board | substrate of MBS type graft copolymer through multi-stage superposition | polymerization, the present inventors controlled the refractive index of the rubber latex of an inner layer and an outer layer of MBS type graft copolymer, and the PVC resin blend containing the same. The present invention has been completed by finding that the color characteristics and the low temperature impact strength change.

The rubber latex used in the preparation of the MBS graft copolymer according to the present invention is a rubber latex having a multi-layered structure, wherein the refractive index of the inner rubber latex is greater than that of the outer rubber latex.

In the present invention, the rubber latex is a copolymer rubber latex of a conjugated diene-based monomer and an ethylenically unsaturated aromatic compound, wherein the conjugated diene-based monomer may be at least one selected from the group consisting of butadiene, isoprene and chloroisoprene, but The ethylenically unsaturated aromatic compounds include, but are not limited to, styrene, alphamethylstyrene, isopropenylnaphthalene, vinylnaphthalene, and benzene and benzene rings in which at least one of each hydrogen of the benzene ring is substituted with an alkyl group of C ₁ to C ₃ At least one of each hydrogen may be one or more selected from the group consisting of styrene substituted with halogen, but is not limited thereto.

In the present invention, in the case of the inner rubber latex forming the rubber latex, the refractive index is preferably 1.54 to 1.59, more preferably 1.545 to 1.59. When the refractive index of the inner layer rubber latex is less than 1.54, the impact strength improvement effect is insignificant, and when the refractive index exceeds 1.59, the whitening degree becomes large, which is not preferable because it may adversely affect the transparency.

In the present invention, in the case of the outer rubber latex forming the rubber latex, the refractive index is preferably 1.51 to 1.54, more preferably 1.51 to 1.535. If the refractive index of the outer rubber latex is less than 1.51, there is a problem that the transparency is lowered, and if the refractive index exceeds 1.54, the impact strength improvement effect is insignificant, which is not preferable.

In the present invention, the graft copolymer prepared by emulsion polymerization of at least one monomer selected from the group consisting of alkyl (meth) acrylate and ethylenically unsaturated aromatic compounds using the rubber latex may be used as an impact modifier of PVC resin. . In the present invention, the graft copolymer may be prepared by emulsion polymerization by adding the monomers in a batch, or may be prepared by emulsion polymerization by dividing the monomer into two or more stages, and the emulsion polymerization method does not limit the present invention.

The content of the rubber latex used in the preparation of the graft copolymer in the present invention is 50 to 95% by weight, the content of at least one monomer selected from the group consisting of the alkyl (meth) acrylate and ethylene unsaturated aromatic compounds. It is preferable that it is 5 to 50 weight%. When the content of the rubber latex used in the preparation of the graft copolymer is less than 50% by weight, the impact reinforcing effect is insignificant, and when the content of the rubber latex is greater than 95% by weight, dispersibility due to the lack of compatibility between the rubber latex and PVC resin This is not preferable because there is a problem that the impact strengthening effect is not effectively exerted eventually.

The alkyl (meth) acrylate that can be used in the preparation of the graft copolymer according to the present invention is one or more selected from the group consisting of methyl methacrylate, ethyl methacrylate, methyl acrylate and ethyl acrylate may be used. But it is not limited thereto.

In addition, the ethylenically unsaturated aromatic compound that can be used in the preparation of the graft copolymer according to the present invention is at least one of each hydrogen of styrene, alpha methyl styrene, isopropenyl naphthalene, vinyl naphthalene, benzene ring C ₁ to One or more selected from the group consisting of styrene substituted with an alkyl group of C ₃ , and styrene with at least one of each hydrogen of the benzene ring substituted with halogen may be used, but is not limited thereto.

In the present invention, a reaction medium, an emulsifier, a stabilizer, an initiator, and the like for emulsification polymerization to prepare the graft copolymer from the rubber latex may be used without particular limitation as known in the art. It is not intended to limit the invention.

The present invention can be prepared by blending the graft copolymer prepared using the rubber latex with a PVC resin PVC resin blend.

The PVC resin blend is characterized in that consisting of 1 to 20% by weight of the graft copolymer and 80 to 99% by weight of the PVC resin according to the present invention. When the content of the graft copolymer according to the present invention is less than 1% by weight in the PVC resin blend according to the present invention, the effect of improving impact resistance is insignificant, and when the content exceeds 20% by weight, the impact strength is no longer increased. It is not preferable because there is a problem that only the manufacturing cost rises excessively without increasing.

In the present invention, the PVC resin is not particularly limited, and any of those known in the art to which the present invention pertains may be used.

Meanwhile, the PVC resin blend according to the present invention may further include additives such as antioxidants, heat stabilizers, plasticizers, colorants, and lubricants known in the art to which the present invention pertains, if necessary.

Next, the manufacturing method of the rubber latex according to the present invention will be described.

Method for producing the rubber latex according to the present invention

(1) preparing an inner layer rubber latex by first emulsion-polymerizing 25 to 75% by weight of a monomer mixture of a conjugated diene monomer, an ethylenically unsaturated aromatic compound and a crosslinking agent; And

(2) emulsion-polymerizing 25 to 75% by weight of the residual monomer mixture in the core layer rubber latex to produce an outer layer rubber latex.

In the reaction of step (1),

The monomer mixture of the conjugated diene monomer, the ethylenically unsaturated aromatic compound and the crosslinking agent is preferably 25 to 75% by weight. When the amount of monomer used in the step (1) is less than 25% by weight relative to the total monomer mixture, there is a problem that the low-temperature impact strength of the PVC resin using the same decreases, and when it exceeds 75% by weight, the color characteristics of the PVC resin There is a problem that both the low temperature impact strength and the low temperature.

The conjugated diene monomer used in the rubber latex production method according to the present invention may be selected from the group consisting of butadiene, isoprene and chloroisoprene. In this case, the conjugated diene monomer serves to absorb shock from the outside to improve impact resistance.

In addition, the ethylenically unsaturated aromatic compound used in the rubber latex production method according to the present invention is at least one of each hydrogen of styrene, alpha methyl styrene, isopropenyl naphthalene, vinyl naphthalene, benzene ring of C ₁ to C ₃ At least one selected from the group consisting of styrene substituted with an alkyl group, and styrene at least one of each hydrogen of the benzene ring is substituted with halogen. The ethylenically unsaturated aromatic compound serves to maintain the transparency of the PVC resin by suppressing the scattering of light generated by the difference in refractive index by making the refractive index of the rubber latex equal to the PVC resin.

In the present invention, a crosslinking agent may be used when preparing the rubber latex, and the crosslinking agent used may be divinylbenzene, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, 1,3 It is preferably at least one compound selected from the group consisting of -butylene glycol dimethacrylate, aryl methacrylate and 1,3-butylene glycol diacrylate. The crosslinking agent serves to control the degree of crosslinking of the rubber latex.

In addition, the content of the graft crosslinking agent used in the rubber latex production method according to the present invention is preferably used 0.1 to 3% by weight, more preferably 0.1 to 1.5% by weight relative to the total monomers. When the amount of the graft crosslinking agent is less than 0.1% by weight, there is a problem that the degree of whitening is deteriorated, and when it exceeds 3% by weight, the impact resistance is lowered.

The refractive index of the inner rubber latex prepared in the step (1) reaction of the present invention is preferably 1.54 to 1.59. When the refractive index is less than 1.54, the impact strength improvement effect is insignificant, and when the refractive index exceeds 1.59, the whitening degree is increased, which may adversely affect transparency.

In addition, in the step (2),

Emulsion polymerization is carried out using the inner layer rubber latex prepared in the step (1) using 25 to 75% by weight of the remaining monomers not used in the step (1). It is preferable that the refractive index of the outer layer rubber latex manufactured by this method is 1.51 to 1.54. If the refractive index is less than 1.51, there is a problem that the transparency is lowered. If the refractive index is more than 1.54, there is a problem that the impact strength improvement effect is insignificant.

The conjugated diene-based monomer, the ethylenically unsaturated aromatic compound and the crosslinking agent used in the production method of the rubber latex of the present invention serve to adjust the refractive index of the rubber latex, the content and type of which can be changed according to the desired physical properties. . Therefore, the content ratio of conjugated diene monomer, ethylenically unsaturated aromatic compound and crosslinking agent is not limited in the present invention, but the amount of conjugated diene monomer: (ethylene unsaturated aromatic compound + crosslinking agent) is used in order to secure transparency through refractive index control. It is preferred to maintain 3: 1 throughout the reactions of steps (1) and (2). However, it is preferable to use 25 to 75% by weight of the monomer in the reaction of step (1) and 25 to 75% by weight of the monomer in the reaction of step (2). In this case, the refractive index of the inner rubber latex prepared in step (1) is preferably 1.54 to 1.59, the refractive index of the outer rubber latex prepared in step (2) is preferably 1.51 to 1.54.

In the method for producing the rubber latex according to the present invention, the reaction medium, emulsifier, stabilizer, initiator, etc. for performing the emulsion polymerization may be used in a conventional content without particular limitation, as long as it is known in the art. In this regard, reference may be made to the description of the following examples.

When the graft copolymer prepared by using the rubber latex prepared according to the present invention is used as an impact modifier in a PVC resin, the color characteristics of the PVC resin are b or less than 10 using a color meter of ASTM 1003 standard, and low temperature impact strength. The color characteristics and impact strength, especially low temperature laminar strength is superior to the existing PVC resin at 300 rpm or more at -20 ℃ by the following evaluation method.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to the following examples, and variations, modifications, and the like that maintain the basic idea of the present invention are understood to be included in the scope of the present invention.

Example

Example  One

(Manufacture of rubber latex)

The weight percentages of the following compounds are based on 100% by weight of the monomer mixture used for the preparation of rubber latex, and parts by weight are based on 100 parts by weight of the monomer mixture.

In a 120 liter high pressure polymerization vessel equipped with a stirrer, 150 parts by weight of ion-exchanged water, 0.5 parts by weight of buffer solution as an additive, 1.0 parts by weight of potassium oleate, 0.0047 parts by weight of ethylenediamine tetrasodium acetate, 0.003 parts by weight of ferrous sulfate, sodium form 0.02 parts by weight of aldehyde sulfoxy acid and 0.1 parts by weight of diisopropylbenzene hydroperoxide were initially charged.

In the first step, 30% by weight of butadiene, 19.5% by weight of styrene and 0.5% by weight of divinylbenzene were polymerized at 35 ° C, and the polymerization conversion rate of the added monomer was 90% or more and 45% of butadiene in the second step. %, 4.5% by weight of styrene, 0.5% by weight of divinylbenzene and 0.5 parts by weight of potassium oleate were polymerized for 10 hours to obtain a styrene-butadiene rubber latex having a particle size of 1000 mm 3, and the final polymerization conversion thereof was 98%.

(Production of MBS Graft Copolymer)

The weight percentages of the following compounds are based on 100% by weight of the mixture of the rubber latex and the newly added monomer used for the preparation of the MBS-based graft copolymer, and the weight parts are 100% of the mixture of the rubber latex and the newly added monomer. It is shown based on parts by weight.

70% by weight of the obtained rubber latex (solid content) was charged to a closed reactor, and charged with nitrogen thereinto 0.0094 parts by weight of ethylenediamine tetrasodium acetate, 0.006 parts by weight of ferrous sulfate, and sodium formaldehyde sulfoxy acid 0.04 After addition of 14 parts by weight of methyl methacrylate, 0.14 parts by weight of potassium oleate, 14 parts by weight of ion-exchanged water, and 0.05 parts by weight of t-butyl hydroperoxide, the polymerization was carried out at 60 DEG C for 10 minutes for 2 hours. 16 weight% styrene, 0.0094 weight part of ethylenediamine tetrasodium acetate, 0.006 weight part of ferrous sulfate, 0.04 weight part of sodium formaldehyde sulfoxylate, 0.16 weight part of potassium oleate, 16 weight part of ion-exchanged water, and After adding 0.05 part by weight of t-butyl hydroperoxide, polymerization was performed at 60 ° C. for 2 hours.

(Manufacture of MBS Powder)

4 parts by weight of magnesium sulfate while stirring by adding 0.5 parts by weight of antioxidant (Irganox-245) to 100 parts by weight of the graft copolymer (MBS graft copolymer) reaction product (liquid phase) of the methyl methacrylate-butadiene-styrene prepared above Part and 2 parts by weight of sulfuric acid were added to separate the polymer and water at 70 ° C., followed by dehydration and drying to obtain MBS powder.

Preparation of PVC Resin Specimen

Specimen preparation of PVC resin was carried out by preparing a PVC resin masterbatch to facilitate processing. PVC resin master batch is 100 parts by weight of PVC resin, 1.5 parts by weight of thermal stabilizer (Sn stearate), 1.0 part by weight of internal lubricant (calcium stearate), 0.5 part by weight of external lubricant (paraffin wax), processing aid (LG Chem, PA- 910) 0.5 parts by weight and 0.3 parts by weight of pigment were prepared by sufficiently mixing at a temperature of 130 ° C. using a high speed stirrer and then cooling.

The amount of impact modifier used to prepare the PVC resin specimens was 9 parts by weight based on 100 parts by weight of the PVC resin, and a sheet of 0.5 mm thickness for low temperature rotational impact strength measurement was prepared using a roll at 195 ° C.

Example  2

In the same manner as in Example 1, but in the rubber latex polymerization 25% by weight of butadiene, 24% by weight of styrene and 1% by weight of divinylbenzene was added, and 50% by weight of butadiene was added to the polymerization in two steps Only thing is different.

Comparative example  One

In the same manner as in Example 1, but in the rubber latex polymerization 37.5% by weight of butadiene, 12% by weight of styrene and 0.5% by weight of divinylbenzene, 37.5% by weight of butadiene, 12% by weight of styrene and It differs only by superposing | polymerizing by adding 0.5 weight% of divinylbenzenes.

Comparative example  2

In the same manner as in Example 1 but in the rubber latex polymerization 45% by weight of butadiene, 4.5% by weight of styrene and 0.5% by weight of divinylbenzene in a step, 30% by weight of butadiene, 19.5% by weight of styrene and It differs only by superposing | polymerizing by adding 0.5 weight% of divinylbenzenes.

Comparative example  3

The polymerization was carried out in the same manner as in Example 1 except that 50 wt% of butadiene was added in one step during the rubber latex polymerization, and 25 wt% of butadiene, 24 wt% of styrene and 1 wt% of divinylbenzene were added in two steps. Only thing is different.

Comparative example  4

In the same manner as in Example 1, except that 75 wt% butadiene, 24 wt% of styrene, and 1 wt% of divinylbenzene in the rubber latex polymerization were carried out in one step.

(Property test)

Refractive index evaluation

The refractive index was measured at 25 ° C. using a refractive index meter (Refractometer, manufactured by Abbe) of a film obtained by heating and drying each prepared latex at 70 ° C.

Glass transition temperature ( Tg Rating

The glass transition temperature was measured while increasing the temperature increase rate to 10 ℃ / min at room temperature using DMTA V of Rheometric Scientific.

Evaluation of low temperature impact strength

The low temperature impact strength was obtained by cutting the sheet prepared by the method of Example 1 to prepare specimens having a thickness of 0.5 mm and 10 cm * 14 cm, and aged at -20 ° C. for 2 hours to rotate the circular saw blade, and then applied to the saw blade at a speed of 15 mm / sec. The lowest rpm at which the specimen was broken was measured.

Evaluation of color characteristics

The sheet prepared by the above method was prepared by using a heat press to prepare a specimen of 3 mm thickness for measuring color characteristics of the ASTM 1003 standard, and b value was measured using a color computer (SUGA Color Computer).

For Examples 1 to 2 and Comparative Examples 1 to 4, the step-by-step refractive index and step-by-step glass transition temperature of the rubber latex for each polymerization step and the color properties and low temperature impact strength of the PVC resin blends prepared according to the above examples and comparative examples were measured, respectively. Table 1 shows.

division Stepwise monomer composition Refractive Index Step 1 / Step 2 Tg step by step Color characteristics (b value) Low temperature impact strength Stage 1 2 steps Example 1 BD 30 SM 19.5 DVB 0.5 BD 45 SM 4.5 DVB 0.5 1.5466 / 1.5244 -43 / -76 7.81 440 rpm Example 2 BD 25 SM 24 DVB 1 BD 50 1.5540 / 1.5170 -27 / -84 7.00 480 rpm Comparative Example 1 BD 37.5 SM 12 DVB 0.5 BD 37.5 SM 12 DVB 0.5 1.5355 / 1.5355 -63 / -60 10.96 280 rpm Comparative Example 2 BD 45 SM 4.5 DVB 0.5 BD 30 SM 19.5 DVB 0.5 1.5244 / 1.5466 -80 / -41 11.89 200 rpm Comparative Example 3 BD 50 BD 25 SM 24 DVB 1 1.5170 / 1.5540 -90 / -25 12.20 180 rpm Comparative Example 4 BD 75 SM 24 DVB 1 1.5355 -63 10.68 250 rpm

In the table, BD represents butadiene, SM represents styrene, and DVB represents divinylbenzene, respectively.

As shown in the table, the color characteristics and low temperature rotation of the PVC resin using the MBS-based graft copolymer prepared by using a rubber latex prepared by varying the refractive index according to the multi-step polymerization method according to the present invention as an impact modifier It was confirmed that the impact strength was improved. That is, when the refractive index of the inner rubber latex is 1.54 to 1.59 and the refractive index of the outer rubber latex is 1.51 to 1.54 as in Examples 1 to 2, the color characteristics of the PVC resin are improved and the low temperature rotational impact strength is increased. However, on the other hand, when the refractive index of the inner layer and outer rubber latex as in Comparative Examples 1 to 4 out of the range, it was confirmed that the color characteristics of the PVC resin is also bad and low-temperature impact strength is low. In particular, it was confirmed that the color characteristics and low temperature rotational impact strength of the PVC resin is worse than the results of the present invention compared to the case of polymerization in a multi-stage when all the monomers are added and polymerized in Comparative Example 4.

Therefore, when the MBS-based graft copolymer using the rubber latex having a refractive index according to the present invention as a substrate, it was confirmed that the color characteristics and low-temperature impact strength were excellent.

As described through the above Examples and Comparative Examples, when the MBS-based graft copolymer prepared by the production method of the present invention is used as the impact modifier of the PVC resin, a PVC resin having excellent color characteristics and low temperature impact strength is produced.

Although the present invention has been described in detail with reference to the embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made within the scope and spirit of the present invention, and such modifications and modifications belong to the appended claims. Do. Therefore, the scope of the present invention is defined by the following claims and their equivalents.

Claims (15)

A rubber latex having a multilayer structure, wherein the refractive index of the inner rubber latex is greater than that of the outer rubber latex. The method of claim 1, Rubber latex, characterized in that the rubber latex is a copolymer rubber latex of a conjugated diene monomer and an ethylenically unsaturated aromatic compound. The method of claim 2, Rubber conjugate, characterized in that the conjugated diene monomer is at least one selected from the group consisting of butadiene, isoprene and chloroisoprene. The method of claim 2, The ethylenically unsaturated aromatic compound is at least one of each of styrene and benzene ring in which at least one of each hydrogen of styrene, alphamethylstyrene, isopropenyl naphthalene, vinylnaphthalene, and benzene ring is substituted with an alkyl group of C ₁ to C ₃ . Is rubber latex, characterized in that at least one member selected from the group consisting of styrene substituted with halogen. The method of claim 1, The refractive index of the inner rubber latex is 1.54 to 1.59, the refractive index of the outer rubber latex is 1.51 to 1.54, the rubber latex. Graft emulsion polymerization of 50 to 95% by weight of the rubber latex of any one of claims 1 to 5 at least 5 to 50% by weight of at least one monomer selected from the group consisting of alkyl (meth) acrylates and ethylenically unsaturated aromatic compounds. Graft copolymer, characterized in that prepared by. The method of claim 6, The graft copolymer, characterized in that the alkyl (meth) acrylate is at least one selected from the group consisting of methyl methacrylate, ethyl methacrylate, methyl acrylate, and ethyl acrylate. The method of claim 6, At least one of styrene, alpha methyl styrene, isopropenyl naphthalene, vinyl naphthalene, and styrene in which at least one of each hydrogen of a benzene ring is substituted with an alkyl group having ₁ to ₃ carbon atoms; Graft copolymer, characterized in that at least one selected from the group consisting of styrene substituted with one halogen. PVC resin blend comprising 1 to 20% by weight of the graft copolymer of claim 6 and 80 to 99% by weight of the PVC resin. (1) preparing an inner layer rubber latex by first emulsion-polymerizing 25 to 75% by weight of a monomer mixture of a conjugated diene monomer, an ethylenically unsaturated aromatic compound and a crosslinking agent; And (2) emulsion-polymerizing 25 to 75% by weight of the residual monomer mixture in the inner rubber latex to produce an outer rubber latex Rubber latex manufacturing method comprising a. The method of claim 10, The conjugated diene monomer is a rubber latex manufacturing method, characterized in that at least one selected from the group consisting of butadiene, isoprene and chloroisoprene. The method of claim 10, At least one of the hydrogens of the styrene and benzene rings in which the ethylenically unsaturated aromatic compound is at least one of styrene, alpha methyl styrene, isopropenyl naphthalene, vinyl naphthalene and benzene ring is substituted with an alkyl group of C ₁ to C ₃ Method for producing a rubber latex, characterized in that at least one selected from the group consisting of styrene substituted with one halogen. The method of claim 10, The crosslinking agent is divinylbenzene, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, aryl methacrylate and 1,3 -Butylene glycol diacrylate method of producing a rubber latex, characterized in that at least one member selected from the group consisting of. The method of claim 10, Method for producing a rubber latex, characterized in that the crosslinking agent is used 0.1 to 3% by weight relative to the total monomers. The method of claim 10, The refractive index of the inner rubber latex is 1.54 to 1.59, the refractive index of the outer rubber latex is 1.51 to 1.54.