KR20000018421A - Manufacturing method of thermoplastic resin having excellent whiteness and impact resistance - Google Patents

Abstract

PURPOSE: The aim is to provide preparing method of thermoplastic resin having excellent whiteness and impact resistance by grafting aromatic-vinyl monomer and unsaturated nitryl monomer homogeneously into gum polymer. CONSTITUTION: This invention is disclosed graft copolymerization method comprising steps of; a) 10 to 35 weight % of 65 to 45 weight parts of graft monomer mixture and molecular weight controller are mixed and agitated in the presence of 35 to 55 weight parts of gum polymer latex for monomer and controller to get into gum particles swelled enough. Then ion exchange water, emulsifier and polymerization initiator is put and heated up to 45 to 60°C. The first graft latex is made when most of graft monomer( 90 to 96 %) is polymerized with redox catalyst mixture at 55 to 70°C, b) polymerization by continuous input of mixed oil soluble polymerization initiator, hydroperoxide, molecular weight controller, and remained graft monomer mixture for 3 to 6 hrs at 70 to 80°C after putting emulsifier right after the first step, and c) polymerization with the agent to minimize unreacted monomer until polymerization rate is 94 to 98 %.

Description

Manufacturing method of thermoplastic resin excellent in whiteness and impact resistance

Field of invention

The present invention relates to a method for producing a thermoplastic resin having excellent whiteness and improved impact resistance. More specifically, industrially advantageous fusion polymerization method is used, and suitable polymerization initiators, emulsifiers and molecular weight regulators are selected and used, and polymerization conditions such as the amount of monomers and the method of dosing are optimally adjusted so that the monomers are uniformly grafted to the rubber particles. It is to provide a method for producing a thermoplastic resin excellent in whiteness and improved impact resistance.

Background of the Invention

ABS resin of thermoplastic resin is composed of styrene which has excellent processability, acrylonitrile which has good rigidity and chemical resistance, and butadiene rubber which has good mechanical properties such as impact resistance. Therefore, it is used very closely in real life such as electric, electronic goods, office equipment. In particular, as the standard of living improves, commercial demands such as the characterization of functions are gradually increasing.

ABS resin is manufactured by block polymerization method, block-suspension polymerization, emulsion polymerization, etc., and is produced using these methods together. In the case of the bulk polymerization produced continuously, the mass production is possible, the production cost is low, and the natural color is excellent, but there are disadvantages that it is difficult to specialize the product, add high value, and diversify the variety of colors such as various colors of the product. . Therefore, the most widely used emulsion polymerization method. However, in the case of emulsion polymerization, despite the advantage that the product can be diversified, various subsidiary materials such as emulsifiers that are put into the polymerization process remain in the final product, and the whiteness of the ABS resin is very weak due to a separate post-process such as a solidification process. I have a problem. Therefore, in order to produce a color with visual quality, it is necessary to add white pigment and to increase the amount of colorant. Will be lowered.

Therefore, a lot of research has been conducted to improve the above problems, but since it is very difficult to manufacture ABS resins having various physical properties, there is no manufacturing method that satisfactorily satisfies them.

For example, in order to improve the color of ABS resin, there is a method of minimizing additives such as emulsifiers that affect the color in emulsion polymerization, but the yield is lowered, the working environment is deteriorated, and the waste treatment cost is increased by increasing the coagulant generated during polymerization. This increase has the disadvantage of being very difficult to apply to actual production.

In addition, a method of mixing a resin produced by emulsion polymerization and a resin produced by block polymerization has been disclosed, but this has a problem in that the quality of the product is poor, such as a complicated process and a decrease in gloss. Although a method of improving the acrylonitrile monomer content affecting the color of the graft monomers is also known, there is a problem in that the rigidity, chemical resistance, etc. of the resin, which is a characteristic of the ABS resin, are lowered. Another method is to change the coagulant used in the coagulation process during the post-process, or to expand the washing process, but this is not preferable because it involves an increase in manufacturing cost and environmental problems due to increased waste water, rather than improving color. Has a problem.

Accordingly, the present inventors use appropriately selected types of molecular weight regulators, emulsifiers, polymerization initiators, redox agents, and chelating agents required for graft polymerization, and use them in an amount or a dosing method and a rubbery polymer. By optimally adjusting the polymerization conditions such as the amount of monomer to be grafted and the method of dosing, the composition of the monomer grafted to the rubber particles is uniform while maintaining the physical properties such as impact resistance and fluidity of the thermoplastic resin. A method for producing a thermoplastic copolymer resin having improved impact properties has been developed.

An object of the present invention is to provide a method for producing a thermoplastic resin excellent in whiteness and impact resistance by uniformly grafting an aromatic vinyl monomer and an unsaturated nitrile monomer in a rubbery polymer.

Another object of the present invention is to provide a method for producing a thermoplastic resin having excellent natural color and improved glossiness.

It is still another object of the present invention to provide a method for producing a thermoplastic resin that retains an excellent balance of physical properties such as impact resistance and fluidity of the ABS resin.

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

The manufacturing method of the thermoplastic resin of this invention is a polymerization method which emulsifies graft copolymerization of an aromatic vinyl monomer and an unsaturated nitrile monomer using the rubbery polymer as a seed. In the graft copolymerization method of the present invention, a part of a monomer mixture and a molecular weight regulator are added to a rubbery polymer, ion-exchanged water, an emulsifier, and a polymerization initiator are added, and then the temperature is increased. Preparing a first step reaction; A second step of graft polymerization by adding an emulsifier to the graft latex, adding the remaining monomer mixture, a molecular weight modifier, and a polymerization initiator in a first step of the reaction; And a third step reaction in which a redox catalyst mixture and a polymerization initiator are added to obtain a graft copolymer latex. The three reaction steps are described in detail below.

Step 1:

In the presence of 35 to 55 parts by weight of the rubbery polymer latex, 10 to 30% of the graft monomer mixture and 65 to 45 parts by weight of the molecular weight modifier are mixed and added, followed by stirring for 20 to 40 minutes to sufficiently swell the monomer and the molecular weight regulator into the rubbery polymer particles. Allow it to enter Then, ion-exchanged water, an emulsifier and a polymerization initiator were added, and the temperature was raised to 45-60 ° C., whereby a redox agent (ferrous sulfate), a reducing agent (sodium formaldehyde sulfoxylate), and a chelating agent (sodium ethylenediaminetetraacetate) were added. The first graft latex is prepared by adding a mixed redox catalyst mixture to polymerize the graft monomer introduced into the first stage reaction in the range of 55 to 70 ° C. and performing the polymerization so that the conversion rate reaches 90 to 96%. .

Second step:

In order to secure the polymerization stability of the first graft latex obtained in the first step reaction, an emulsifier is added at the same time as the end of the first step reaction, and the remaining amount of the graft monomer mixture and the hydroperoxide oil-soluble polymerization initiator previously mixed with the molecular weight regulator. Was continuously added over 3 to 6 hours to carry out the graft polymerization reaction. At this time, the reaction heat is adjusted so that the reaction temperature is in the range of 70 to 80 ℃.

Step 3:

After completion of the second stage reaction, the redox catalyst mixture and the hydroperoxide oil-soluble polymerization initiator are mixed with a redox agent (ferrous sulfate), a reducing agent (sodium formaldehyde sulfoxylate), and a chelating agent (sodium ethylenediaminetetraacetate). It is added in the range of 70 ~ 80 ℃ to improve the polymerization conversion rate, minimize the unreacted monomer and at the same time shorten the polymerization time. In this case, graft latex having a final polymerization conversion rate of 94 to 98% and a solid content of 38 to 44% by weight is obtained.

Polybutadiene, butadiene-styrene copolymer latex and the like may be used as the rubbery polymer in the present invention, and a conjugated diene-based rubbery polymer latex having a gel content of 70 to 85% by weight may be preferably used. In addition, the average particle diameter of the rubber latex is preferably in the range of 0.26 to 0.36 mu m, more preferably in the range of 0.28 to 0.33 mu m. When the rubber having a mean particle size of rubbery polymer is smaller than 0.26 μm, the surface gloss of the final molded product is excellent, but the impact resistance is deteriorated, which is not preferable. When the rubber having an average particle size of 0.36 μm or more is used, it is advantageous to improve the fluidity. There is a disadvantage in that the impact is lowered, and in particular, since the coagulum is excessively generated during graft copolymerization and the surface of the final molding is lowered, it is not suitable for the present invention.

The amount of the rubbery polymer is preferably 35 to 55 parts by weight based on the solid content of the graft polymer. If the amount is less than 35 parts by weight, the graft copolymer input amount must be increased to improve the impact strength when mixed with the matrix SAN resin, thereby decreasing the fluidity and decreasing the whiteness. The graft rate cannot be sufficiently increased, and in particular, it is difficult to recover the fine powder by adhesion between particles in the solidification process. In addition, large particles may cause yellowing of the powder due to thermal history during the drying process, thereby greatly reducing the color and causing a deterioration in appearance of the final molded product.

The graft copolymer of the present invention is prepared by graft polymerizing from 65 to 45 parts by weight of the monomer mixture consisting of 67 to 77% by weight of the aromatic vinyl monomer and 33 to 23% by weight of the unsaturated nitrile monomer to 35 to 55 parts by weight of the rubbery polymer. . When the content of the aromatic vinyl monomer exceeds 77% by weight (that is, when the content of unsaturated nitrile monomer is less than 23% by weight), the chemical resistance and rigidity of the final product is lowered and when the content of the aromatic vinyl monomer is less than 67% by weight (that is, unsaturated When the content of the nitrile monomer exceeds 33% by weight), the homopolymer and the continuous chain formation of the unsaturated nitrile monomer increase during the graft emulsion polymerization, and a large amount of coagulum is generated and the color of the final molded product is reduced.

In the graft monomer mixture, 10 to 30% of the total mixture is added during the first step reaction, and 90 to 70% is added to the second step reaction. 10-30% of the monomer mixture added to the first stage reaction is added in the presence of rubbery latex and stirred for 20 to 40 minutes, which infiltrates most of the monomer mixture into the rubber particles, which is advantageous for impact strength. To induce a lot of occlusion SAN. If the monomer mixture is added at 10% or less during the first stage reaction, the impact resistance is lowered. If 30% or more is added, the initial reaction is very violent, temperature control is difficult, and polymerization stability is deteriorated. .

In the second step, 90 to 70% of the monomer mixture remaining after the first step should be continuously added for 3 to 6 hours. It is to suppress the formation of SAN to minimize the color degradation due to heat discoloration in the extrusion and injection process, and to improve the whiteness by minimizing the continuous chain of the water-soluble monomer. If the feeding time is faster than the above range, the polymerization speed is increased, which lowers the polymerization stability and at the same time it is difficult not only to induce a uniform graft reaction on the rubber surface, but also to obtain an appropriate graft rate. This leads to a decrease in productivity due to the long time required, which is very disadvantageous industrially.

Molecular weight modifiers that can be used in the present invention include mercaptans such as alphamethylstyrene dimer, terpinolene, tertiarydecyl mercaptan or mixtures thereof. Of these, terpinolene, terricidodecyl mercaptan or a mixture of terpinolene and terricidodecyl mercaptan can be preferably used. In the first step, the molecular weight modifier is preferably added in a batch, and in the second step, it is preferable to continuously mix and mix the monomer mixture. This is one of the important conditions in the present invention together with the polymerization initiator which is added continuously during the second stage reaction. The amount of the molecular weight modifier used is preferably 0.02 to 0.15 parts by weight in the first step, 0.05 to 0.45 parts by weight in the second step. When the amount of the molecular weight modifier is less than the above range, it is difficult to control the proper graft ratio, which greatly reduces the impact resistance and appearance of the final product, and when used in excess of the above range, there is a problem that excessive coagulation occurs while reducing the overall speed. The graph rate is lowered.

As the emulsifier used in the present invention, fatty acid salts such as potassium stearate, sodium stearate, potassium oleate or potassium rosinate can be used. In particular, emulsifiers in accordance with the object of the present invention is potassium stearate or sodium stearate excellent in the color of the emulsifier itself so as to remain in the resin after the post-solidification process. The emulsifier is preferably used 0.1 to 0.5 parts by weight in the first step, 0.2 to 0.8 parts by weight in the second step. If the amount of the emulsifier is smaller than the above range, the polymerization stability is lowered, which is not preferable. If the amount of the emulsifier is more than the above range, gas may be generated in the molded product of the final product, thereby lowering the quality of the product.

The polymerization initiator that can be used in the present invention is a hydroperoxide-based redox oil-soluble mixture of one or two or more selected from t-butylperoxybenzoate, t-butylperoxyacetate, isocumyl hydroperoxide and cumene hydroperoxide. Initiator. In order to improve the whiteness of the double resin, t-butylperoxybenzoate or t-butylperoxyacetate having a relatively low color degradation by by-products after radical decomposition is preferable. The amount of these used is preferably 0.05 to 0.15 parts by weight in the first step, 0.12 to 0.35 parts by weight in the second step in consideration of the degree of polymerization property control, color improvement, impact resistance and the like.

Co-initiators that can be used in combination with the hydroperoxide-based redox oil-soluble initiator used as the main initiator include ferrous sulfate, sodium formaldehyde sulfoxylate, and sodium ethylenediaminetetraacetate. The ferrous sulfate is a redox agent, sodium formaldehyde sulfoxylate is a reducing agent and sodium ethylenediaminetetraacetate is a chelating agent. In addition, there is dextrose as a reducing agent, which is easily decomposed even at low temperature, and it has a characteristic of uniformizing the reaction by acting as a reducing agent, but it is disadvantageous in color improvement because it is easily discolored by heat because it remains in the resin. There is this. In addition, there is tetrasodium pyrophosphate as a chelating agent, but there is a problem of lowering the color of the resin when metal ions are present in the resin. The ferrous sulfate, sodium formaldehyde sulfoxylate, and sodium ethylenediaminetetraacetate were mixed to form an aqueous solution to initiate a polymerization of a portion of the mixed redox catalyst mixture in the first step, while remaining a redox catalyst mixture. Is added to the third stage reaction to minimize polymerization conversion and unreacted monomers.

The graft copolymer latex obtained in the polymerization reaction of step 3 was coagulated with 0.5 to 1.5% sulfuric acid aqueous solution, dried to obtain a white powder, and then a copolymer of an aromatic vinyl compound and an unsaturated nitrile compound prepared by bulk or suspension polymerization separately. (SAN resin), a stabilizer and a lubricant are mixed with an appropriate content to produce a thermoplastic resin (ABS resin) with excellent whiteness and improved impact resistance through an extrusion and injection process.

In order to meet the object of the present invention, the graft ratio of the thermoplastic resin should be 45 to 65%. If the graft ratio is lower than this, it is difficult to obtain a white powder with a uniform particle size distribution during solidification and drying.In addition, pinholes and sand surfaces appear as unplasticized particles on the surface of the molded product during compression and injection, resulting in a decrease in surface glossiness. It is not preferable because impact resistance falls. On the other hand, when it is higher than the above range, there is a high probability that a continuous chain of acrylonitrile monomer, which is a water-soluble monomer, is formed, thereby decreasing the color of the powder, reducing the whiteness of the final product, and lowering the fluidity. Hard to get

The present invention will be further illustrated by the following examples, which are merely illustrative of the present invention and are not intended to limit or limit the scope of the present invention.

Example

Example 1

A 30L reactor equipped with a paddle type stirrer, a temperature controller, a heating mantle, a cooling circulator, a condenser, and a continuous input device of a monomer mixture and a polymerization initiator was prepared with a polybutadiene rubber polymer latex having a gel content of 75% and an average particle diameter of 0.30 μm. 50 parts by weight of solids, 2.84 parts by weight of acrylonitrile, 7.16 parts by weight of styrene and 0.10 parts by weight of terpinolene were added thereto, followed by agitation for 20 minutes to sufficiently swell the monomer and the molecular weight modifier into the rubbery polymer particles. Then, 150 parts by weight of ion-exchanged water, 0.30 part by weight of potassium stearate and 0.1 part by weight of t-butylperoxybenzoate were added, and the reactor temperature was raised to reach 50 ° C. When the internal temperature of the reactor reached 50 ° C, stirring was continued for 10 minutes, followed by adding 0.003 parts by weight of ferrous sulfate, 0.08 parts by weight of tetrasodium ethylenediaminetetraacetate, and 0.15 parts by weight of sodium formaldehyde sulfoxylate. Started. When the reaction was initiated, the temperature inside the reactor was 63 ° C. over 40 minutes by self-heating and proper heating, and the reaction was continued for 10 minutes, and then the first stage reaction was terminated.

After the completion of the first step, 0.20 parts by weight of potassium rosin acid was added into the reactor and stirred for 10 minutes. 11.33 parts by weight of acrylonitrile, 28.67 parts by weight of styrene, and 0.15 parts by weight of terpinole were stirred in a stirred container, followed by t-butyl The second stage reaction was terminated by continuously adding the same amount with 0.2 parts by weight of peroxybenzoate for 4 hours while allowing the reactor temperature to be 78 ° C. through self-exotherm and heat of reaction.

After completion of the second reaction, 0.001 parts by weight of ferrous sulfate, 0.05 parts by weight of sodium formaldehyde sulfoxylate, and 0.03 parts by weight of tetrasodiumethylenediaminetetraacetate were added to make the reaction temperature 80 ° C. by spontaneous heating. After the reaction was continued for a minute, it was cooled using a cooling circulation apparatus, and when the temperature inside the reactor reached 65 ° C, 0.35 parts by weight of 2,6-di-t-butylmethylphenol was added as an antioxidant, and the graph was terminated in a three step reaction. The copolymer latex was prepared, wherein the polymerization rate after the completion of the polymerization was 97% and the solid content of the obtained latex was 39.2%.

Example 2

40 parts by weight of butadiene rubber latex was used, except that 3.6 parts by weight of acrylonitrile and 8.4 parts by weight of styrene were added during the first stage reaction in the monomer mixture, and 14.4 parts by weight of acrylonitrile and 33.6 parts by weight of styrene were added to the second stage reaction. Graft copolymer latex was prepared in the same manner as in Example 1.

Example 3

The same process as in Example 1 except that 10.8 parts by weight of styrene and 4.2 parts by weight of acrylonitrile were used in the graft monomer mixture, and 25.2 parts by weight of styrene and 9.8 parts by weight of acrylonitrile were used in the second step. A graft copolymer latex was prepared.

Example 4

A graft copolymer latex was prepared in the same manner as in Example 1, except that the input time of the monomer mixture, the molecular weight regulator, and the polymerization initiator was 6 hours in the second reaction.

Comparative Example 1

Exclude the redox catalyst mixture (ferrous sulfate, sodium formaldehyde sulfoxylate and sodium ethylenediaminetetraacetate) and use potassium persulfate, a water-soluble polymerization initiator, instead of oil-soluble polymerization initiator, and tertiaryodecyl instead of terpinolene as a molecular weight regulator. A graft copolymer latex was prepared in the same manner as in Example 1, except that mercaptan was used and 0.10 parts by weight of the first step reaction and 0.20 parts by weight of the second step reaction were added.

Comparative Example 2

Graft copolymer latex was prepared in the same manner as in Example 1, except that sodium pyrophosphate as a chelating agent, dextrose as a reducing agent, and cumene hydroperoxide as a polymerization initiator were used.

Comparative Example 3

Sodium pyrophosphate as a chelating agent, dextrose as a reducing agent, tisholidodecyl mercaptan as a molecular weight regulator, potassium rosinate as an emulsifier, and cumene hydroperoxide as a polymerization initiator, and the monomer mixture added in the second step reaction was used for 2 hours. A graft copolymer latex was prepared in the same manner as in Example 1, except that continuous injection was carried out over.

The graft copolymer latex prepared according to Examples 1 to 4 and Comparative Examples 1 to 3 was coagulated with isopropyl alcohol to obtain a white powder, which was dissolved in acetone, centrifuged, and the insolubles were washed and dried. After graft rate was measured and listed in Table 1. The graft rate formula is as follows.

The graft copolymer latex prepared in Examples 1 to 4 and Comparative Examples 1 to 3 was filtered through a 200 mesh wire mesh, and the coagulum which did not pass through the mesh was measured after drying at 100 ° C. for 6 hours, and the coagulum content of the solid content. Was calculated according to the following formula and shown in Table 1.

The latex passed through the mesh was coagulated with a 1% sulfuric acid aqueous solution and then dehydrated and dried to recover a white powder having a water content of 0.5% or less, followed by 30 parts by weight of powder and 70 parts by weight of a SAN resin having a weight average molecular weight of 125,000. After mixing, pressing and injection molding to prepare a specimen for measuring the physical properties. For specimens, Izod impact strength was measured according to ASTM D256, glossiness was measured according to ASTM D523, yellowness and whiteness were measured according to ASTM D1925, and the results are shown in Table 1.

Example Comparative Example One 2 3 4 One 2 3 Graft Rate (%) 53 60 58 62 48 64 60 Coagulation content (%) 0.15 0.19 0.18 0.13 0.25 0.21 0.35 Izod impact strength (1/4 ", ㎏cm / ㎝, 23 ℃) 22.8 24.5 22.9 23.2 16.8 21.3 22.2 Flow index (g / 10min 200 ℃, 5㎏) 2.2 2.0 2.1 2.1 2.2 2.2 2.1 Glossiness (60 °) 95.8 96.1 95.1 96.3 97.5 97.6 97.8 Yellow road 7.6 8.0 7.9 7.0 14.5 18.6 19.4 Whiteness 78.9 79.1 78.5 79.8 74.8 72.3 72.1

In the thermoplastic resin manufacturing method of the present invention, the type, dosage, and input method of an emulsifier, a molecular weight modifier, a polymerization initiator, a redox agent, a chelating agent, etc. are adjusted to conditions suitable for graft emulsion polymerization, and a monomer dosage and a method of dosing graft copolymers are adjusted. By controlling the degree, the graft copolymer has a uniform graft form, and thus has the effect of providing a thermoplastic resin excellent in whiteness and impact resistance. In addition, the thermoplastic resin prepared according to the present invention has excellent natural color and glossiness while maintaining physical balance such as impact resistance and fluidity of the styrene resin.

Simple modifications or variations of the present invention can be readily understood by those skilled in the art, and all such modifications or changes can be seen to be included within the scope of the present invention.

Claims (8)

In the presence of 35-55 weight part of rubbery polymer latex, some of 65-45 weight part of monomer mixtures which consist of 67-77 weight% of aromatic vinyl monomers and 33-23 weight% of unsaturated nitrile monomers are thrown into a reactor, a molecular weight regulator is added, and it stirs. A first reaction step of adding an emulsifier, a polymerization initiator, and ion-exchanged water, then raising the reactor, and adding a redox catalyst mixture to prepare a first graft latex; A second reaction step of adding an emulsifier to the graft latex and continuously adding the monomer mixture, the molecular weight regulator and the polymerization initiator remaining after the first step reaction for 3 to 6 hours; And A third reaction step of preparing a graft latex by adding a redox catalyst mixture and a polymerization initiator at the same time as the second step polymerization is completed; Method for producing a thermoplastic resin excellent in whiteness and impact resistance, characterized in that consisting of. The method of claim 1, wherein the rubber polymer latex is a conjugated diene-based rubber polymer latex having a gel content of 70 to 85% by weight and an average particle diameter of 0.26 ~ 0.36㎛, the thermoplastic resin having excellent whiteness and impact resistance Way. The thermoplastic resin having excellent whiteness and impact resistance according to claim 1, wherein 10 to 30% of the 65 to 45 parts by weight of the monomer mixture is added to the first reaction step and 90 to 70% is added to the second reaction step. Method for producing a resin. The method of claim 1, wherein the molecular weight modifier is selected from the group consisting of alpha methyl styrene dimer, terpinolene, tertisil dodecyl mercaptan, and mixtures thereof, 0.02 to 0.15 parts by weight in the first reaction step and the second reaction Method for producing a thermoplastic resin excellent in whiteness and impact resistance, characterized in that the step of adding 0.05 to 0.45 parts by weight. The method of claim 1, wherein the emulsifier is a fatty acid salt such as potassium stearate, sodium stearate, potassium oleate or potassium rosinate, 0.1 to 0.5 parts by weight in the first reaction step and 0.2 to 0.8 in the second reaction step A method for producing a thermoplastic resin having excellent whiteness and impact resistance, characterized by adding a weight part. According to claim 1, wherein the polymerization initiator is redox oil-soluble mixed with one or more selected from the group consisting of t- butyl peroxy benzoate, t- butyl peroxy acetate, isocumyl hydroperoxide and cumene hydroperoxide A method for producing a thermoplastic resin having excellent whiteness and impact resistance, wherein the polymerization initiator is 0.05 to 0.15 parts by weight in a first reaction step and 0.12 to 0.35 parts by weight in a second reaction step. The method for producing a thermoplastic resin having excellent whiteness and impact resistance according to claim 1, wherein the redox catalyst mixture is made of ferrous sulfate, sodium formaldehyde sulfoxylate, and sodium ethylenediaminetetraacetate. The thermoplastic resin according to claim 1, wherein the graft ratio of the resin is 45 to 65%.