KR20000055262A - Method for preparing thermoplastic resin with good impact resistance and natural color property - Google Patents

Abstract

PURPOSE: A method for preparing a thermoplastic resin having good high impact property and natural color is provided to obtain a thermoplastic resin that maintains excellent gloss and flow property of ABS resin and has improved high impact property and natural color. CONSTITUTION: A method for preparing a thermoplastic resin having good high impact property and natural color according to the present invention comprises mixing and processing a graft copolymer and SAN resin to obtain a thermoplastic resin wherein the method is characterized by comprising the steps: a) first graft reacting step wherein 40 to 60 parts by weight of rubber latex which has average particle diameter of graft copolymer between 0.25 and 0.34 micrometer and 70 to 90% of gel content is copolymerized with 60 to 40 parts by weight of graft monomer mixture comprising styrene and acrylonitrile in the presence of a liposoluble initiator inside the rubber; and b) second graft copolymerizing step wherein the said graft reacted copolymer envelops the surfaces of rubber particles in the presence of a water-soluble pyrolysis initiator.

Description

Manufacturing method of thermoplastic resin excellent in impact resistance and natural color {METHOD FOR PREPARING THERMOPLASTIC RESIN WITH GOOD IMPACT RESISTANCE AND NATURAL COLOR PROPERTY}

The present invention relates to a method for preparing a thermoplastic resin having excellent impact resistance and natural color, and more particularly, to a graft copolymer by using a polymerization initiator having different characteristics when preparing a graft copolymer by emulsion polymerization. The present invention relates to a method for manufacturing a thermoplastic resin having excellent impact strength, fluidity, and natural color by adjusting the morphology of the rubber.

Generally, acrylonitrile-butadiene-styrene copolymer (hereinafter referred to as "ABS resin") has relatively good physical properties such as impact resistance, mechanical strength, moldability, glossiness, and the like, so that electrical, electronic parts, office equipment, automobile parts, etc. It is widely used, and also in the manufacturing method, it is largely manufactured and commercialized by the continuous block polymerization method and the batch emulsion polymerization method.

In the case of the double continuous bulk polymerization method, despite the advantages of mass production, low manufacturing cost, and excellent natural color, it is impossible to achieve product diversification and specialization, high value-added and impact resistance characteristics of ABS resin produced by emulsion polymerization method. Due to the deterioration of the balance of glossiness, glossiness, etc., its use is very limited. However, most of ABS resins are manufactured by emulsion polymerization method because they are mixed with products having specific properties or ABS resins produced by emulsion polymerization method. This is mainstream.

However, the ABS resin produced by emulsion polymerization has advantages of relatively good impact resistance, fluidity, thermal properties, balance, and good gloss, but is mixed with styrene-acrylonitrile copolymer (hereinafter referred to as "SAN resin"). In the present invention, the physical properties of the SAN resin composition and impact resistance, while maintaining the existing physical properties, while a good natural color is required to obtain a sufficiently satisfying physical properties.

For example, thermoplastic resins with heat resistance used in automobiles and exterior materials, or thermoplastic resins that require impact strength and tensile properties in particular, are hard thermoplastics that have heat and tensile properties by providing sufficient impact resistance even with low rubber content. By increasing the resin content, a thermoplastic resin having excellent impact strength, heat resistance, and tensile properties can be obtained, and the excellent natural color can minimize the amount of white pigment, etc., when manufacturing resins of various colors, thereby reducing the manufacturing cost. .

Therefore, in order to compensate for these disadvantages, there are a number of known methods up to now, but the most widely used method is to increase the average particle diameter by mixing rubber having a high particle diameter and low gel content with single or relatively small particle diameter rubber. After that, the method of preparing the graft copolymer has become mainstream.

However, the impact resistance is somewhat improved by the use of rubber having a large particle diameter, but the glossiness of the ABS resin is severely deteriorated. Therefore, there are many problems in the practical application. Especially, when the emulsion graft copolymer is manufactured, the average particle diameter is 0.5 μm or more and the gel content is increased. When using less than 50% of the rubber there was a problem that a large amount of coagulation occurs during the polymerization.

Therefore, to improve this, the polymerization stability is improved by increasing the emulsifier, but the problem of deterioration of natural color caused by the excessive addition of the emulsifier used in the emulsion graft copolymerization has not been improved.

As another method, a method of increasing the molecular weight or acrylonitrile content of the SAN resin and improving the amount of graft copolymer by increasing the amount are known, but such a method also has a severe decrease in fluidity compared to the degree of impact resistance. In particular, there is a disadvantage that the natural color is further reduced.

An object of the present invention is to solve the conventional problems as described above, the rubber structure of the graft copolymer while using the rubber particle size commonly used in the manufacture of the emulsion graft copolymer by an industrially simple method In the one-step graft polymerization process, the monomers are mostly polymerized inside the rubber to impart impact resistance, and in the two-step graft polymerization process, the rubber surface is completely surrounded by the graft monomer so as to maintain the appearance of the resin well. The present invention provides a method for preparing a graft copolymer having excellent impact resistance and excellent natural color, comprising preparing a graft copolymer having a core-shell structure and optimizing a graft ratio.

The present invention is one selected from 40 to 60 parts by weight (based on solids) of a rubbery polymer having an average particle diameter of 0.25 to 0.34 µm and a gel content of 70 to 90% by weight, an aromatic vinyl compound which is a graft monomer, and an unsaturated nitrile compound, or One or more graft reactions in which at least two kinds of polymers are mostly polymerized in rubber using 0.03 to 0.15 parts by weight of a fat-soluble polymerization initiator, and 0.20 to 0.50 parts by weight of a water-soluble pyrolytic polymerization initiator when the polymerization conversion rate reaches a certain stage. The present invention relates to a method for producing a thermoplastic resin having excellent impact resistance and natural color by a two-stage graft reaction for preparing a core-shell structured graft copolymer surrounded by graft monomers.

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

First, the graft reaction of the first step is performed in the presence of 40 to 60 parts by weight of a rubbery polymer having an average particle diameter of 0.25 to 0.34 µm. 40 parts by weight and 10 to 40% of the graft monomer mixture 100 and a fat-soluble pyrolysis initiator were mixed and stirred, and then added, followed by addition of a molecular weight regulator and ion-exchanged water, and then heated to 40 to 50 ° C. Stirring was continued for 40 minutes so that most of the first-grafted graft monomers were swollen into the rubber particles, followed by adding an emulsifier and raising the temperature of the reactor to initiate polymerization.

At this time, when the internal temperature of the reactor reaches 60-75 ° C, the internal temperature of the reactor is maintained at 60-75 ° C using a cooler, and the reaction is continued for 30-60 minutes, and the polymerization conversion rate reaches 93% or more. Prepare coalescing latex.

As the rubbery polymer usable in the present invention, a polybutadiene or a copolymer containing at least 80% by weight of butadiene, for example, butadiene-styrene copolymer, butadiene-acrylonitrile copolymer, butadiene-acrylic acid copolymer and the like Rubbery polymer latexes can be used.

The average particle diameter thereof is preferably in the range of 0.25 to 0.34 μm. When the rubber particle diameter is less than 0.25 μm, the surface glossiness and natural color of the final molded product are slightly improved, but the efficiency of rubber for imparting impact resistance is improved. However, the impact strength is lowered. On the other hand, when rubber having a particle diameter of more than 0.34 μm is used, the impact resistance and fluidity are slightly improved, but the mechanical stability of the graft copolymer is deteriorated, resulting in excessive coagulation. Not only does this occur, but stability is improved when a large amount of emulsifier is used to improve it, but the surface gloss of the final molded product and the natural color deterioration due to a large amount of emulsifier, as well as the generation of gas during injection molding There are a lot of problems in realizing the loss of value.

In addition, the gel content of the rubbery polymer is in the range of 70 to 90% by weight, but if the gel content is less than 70% by weight, the polymerization proceeds more than necessary in the rubber particles, and the shape of the rubber tends to change, thereby solidifying during polymerization. There is a possibility that the amount of water generated increases, and the glossiness in the final molded article is lowered, which is not preferable. On the other hand, when it exceeds 90% by weight, the efficiency of the rubber is lowered, so that the improvement of impact resistance becomes difficult to expect.

In the present invention, the content of the rubbery polymer is preferably in the range of 40 to 60 parts by weight based on solid content. When the content of the rubbery polymer is less than 40 parts by weight, the polymerization stability may decrease due to the increase in the polymerization rate due to the increase of the graft monomer, which may cause a large amount of coagulum, and also to maintain the same rubber content in the final ABS resin. Since the required amount of the copolymer is increased, the productivity is lowered and the natural color of the final product is lowered.

On the other hand, in the case of exceeding 60 parts by weight, the graft rate cannot be sufficiently increased due to the decrease of the graft monomer, and the graft reaction proceeds unevenly inside the rubber particles and the surface of the rubber particles. Since it cannot be manufactured, it is difficult to recover the fine powder by adhesion between particles in the solidification and drying process, so that the surface gloss and appearance of the final molded product are degraded, and the impact resistance is also hardly expected.

Next, water-soluble pyrolysis initiator was added to the reactor in the presence of the first graft copolymer latex prepared by the first step graft reaction, stirred for 5 to 15 minutes, and the remaining amount of the graft monomer mixture was 90 to 60% and the molecular weight. Mixing and stirring the control agent, and the continuous dosing method was added over 2 to 5 hours to allow a small amount of graft monomers to participate in the graft reaction at a constant rate while at the same time 30 minutes from the start of continuous dosing of the graft monomers After the addition of a small amount of emulsifier in a batch method to provide a second graft copolymer latex to prevent the formation of coagulation by providing an emulsifier micelle (micelle) to the rubber surface weakened by the graft reaction 2 It consists of a step graft reaction.

At this time, the polymerization temperature of the secondary graft copolymerization reaction is preferably 60 ~ 75 ℃, and when the addition of the continuous graft monomer is finished, the reactor temperature is raised to 70 ~ 85 ℃ after the reactor temperature reaches 70 ~ 85 ℃ If it lasts for 20 to 60 minutes and the final polymerization conversion reaches 93 to 98%, forced cooling is terminated to obtain a graft copolymer latex having a solid content of 38 to 44% by weight.

Among the graft monomers used in the first and second graft reactions when preparing the graft copolymer, most of the monomers used in the first graft reaction swell rubber latex particles to polymerize more monomers in the rubber. The graft monomer that is continuously added in the step reaction has the graft reaction uniformly around the rubber so that the graft SAN has a uniform balance in the inside and outside of the rubber particles, thereby obtaining the desired physical properties. Outside the range set forth in the present invention, the composition and the balance of the monomers grafted into and out of the rubber are not suitable, which is not preferable.

In particular, when the monomer mixture to be subjected to the one-step graft reaction exceeds the above range, the graft reaction proceeds in the rubber more than necessary, resulting in excessive swelling of the rubber particles and deterioration of the stability of the polymerization system due to the rapid reaction. It is difficult to obtain a graft copolymer having a core-shell structure in which graft SAN is uniformly polymerized on the surface of the rubber particle due to a lack of graft monomer to be continuously added in two stages due to insufficient graft ratio or the like.

On the other hand, when using less than the above range can not sufficiently obtain the SAN formed in the rubber that is advantageous for the impact strength can not meet the object of the present invention.

In addition, the reaction temperature should also be controlled during the graft polymerization. If the polymerization temperature is lower than the above range during the one and two-step graft reaction, the polymerization rate is slowed, and the productivity is decreased. When the polymerization rate is high, the stability of the graft polymerization system is deteriorated. There is a problem that a large amount of coagulum is likely to occur.

In particular, if the polymerization temperature is lower than the above range during the one-step graft reaction, the decomposition rate of the oil-soluble polymerization initiator, which is a particularly important thermal decomposition initiator in the present invention, is lowered, thereby reducing the polymerization rate as well as the rubber structure of the graft copolymer of the present invention. It is difficult to obtain.

In addition, the type, amount and addition rate of the emulsifier, the molecular weight regulator and the polymerization initiator are also very important. In particular, the method and the amount of the polymerization initiator and the molecular weight control agent is very important to control the graft ratio and the non-graft polymer, etc. to the physical properties according to the object of the present invention, and also plays a very important factor in the reaction rate and polymerization stability.

The polymerization initiator used in the present invention is particularly important in the present invention, and by using a fat-soluble and water-soluble pyrolysis initiator alone, a graft copolymer having excellent impact resistance and natural color can be obtained.

The initiator which can be used for the one-step graft reaction is preferably a fat-soluble polymerization initiator, in particular acetylchlorohexylsulfonylperoxide, 2-2'azobis-2,4-dimethylvaleronitrile, 2-2'azobis- ( 2-amidinopropane) dihydrochloride, lauroyl peroxide, 2-2'-azobisisobutylonitrile, benzoyl peroxide, dimethyl-2,2'-azobisisobutylonitrile 0.03-0.15 parts by weight good.

As a polymerization initiator that can be used for the two-stage graft reaction, a commonly used water-soluble pyrolysis initiator may be used. However, potassium persulfate or sodium is advantageous for uniformly grafting graft monomers on the rubber surface and is easy to initiate polymerization even at low temperatures. Although percellate is good, more preferably 0.20 to 0.50 parts by weight of potassium persulfate.

If the type of the first and second stage polymerization initiator of the polymerization initiator is out of the above conditions, it is impossible to prepare the graft copolymer for the present invention, and if the amount is lower than the above range in the amount of the polymerization initiator, the graft ratio cannot be sufficiently raised and unreacted. As the monomer is increased, an excessive amount of the non-grafted polymer is formed, which is not preferable. When the amount is greater than the above range, there is a problem in that the polymerization system is unstable due to an increase in the reaction rate, thereby increasing the amount of coagulant generated.

The emulsifier which can be used in the present invention is not particularly limited and may be any one used in a conventional emulsion polymerization method. Examples thereof include fatty acid metals such as sodium laurate, sodium oleate, potassium oleate, potassium stearate and the like, sodium lauyl sulfate, potassium rosinate and the like.

Preferably, potassium stearate or potassium rosinate may be used alone or in combination. The amount of these used is preferably 0.1 to 1.0 parts by weight, and preferably 0.1 to 0.8 parts by weight for the two-step graft reaction. If the amount of the emulsifier is used in a smaller amount than the above range, a large amount of coagulant is generated in the latex. In addition, it is not preferable because the appearance of the molded article during the injection molding may cause a gloss decrease due to gas generation.

On the other hand, the method of adding the emulsifier is also important, especially in the case of the primary emulsifier is preferably added after the graft monomers are mostly swollen into the rubber particles.

This is stabilized by rubber particles or emulsifier micelles in the case of graft monomer to which the polymerization initiator is injected. Before the graft monomers are mostly swollen into the rubber, an emulsifier is added or the emulsifier added in the two-stage reaction is combined with the one-stage graft reaction. This is because when it is added, the graft monomers stabilized by the emulsifier are increased, so that it is difficult to sufficiently induce the graft reaction in the rubber particles, and thus it is difficult to fully satisfy the object of the present invention.

As the molecular weight modifier used in the present invention, it is preferable to use one or two or more kinds of mercaptans having 8 to 18 carbon atoms or organic halogen compounds and one or two or more selected from alphamethylstyrene duplex, terpinolene and alpha terpinene. The amount thereof is preferably 0.005 to 0.10 parts by weight for the one-step graft reaction and 0.05 to 0.35 parts by weight for the two-step graft reaction. When the amount of these used is less than the above range, the latex stability is lowered by excessive graft reaction, and the physical properties of the final molded product are decreased. When the amount is used excessively, the lowering of the productivity and the graft rate due to the decrease of polymerization rate are controlled. It is difficult to do it, and in particular, in the method of adding the molecular weight regulator to be added to the two-stage reaction, it is preferable to continuously mix the graft monomer.

In order to evaluate the stability of the graft copolymer latex prepared as described above, the coagulum which failed to pass by filtering the graft copolymer latex through a mesh of about 200 mesh (mesh) was dried by dehydration with water and dried according to the following Equation 1 below. Obtain the amount of coagulation.

In addition, the graft ratio is the graft copolymer latex prepared according to the above method by coagulation with isopropyl alcohol, dehydrated and dried to obtain a white powder, dissolved in acetone, centrifuged and insoluble to dry, the basis weight is It can measure by.

In order to meet the object of the present invention, the graft ratio of the graft copolymer should be 40 to 65%. When the graft ratio of the graft copolymer is lower than this, it is difficult to obtain a white powder having a uniform particle distribution during coagulation and drying, and the affinity between graft SAN and SAN used as a matrix when mixed with a thermoplastic resin prepared separately is processed. In addition, the impact resistance is lowered, and when injection molding, fish-eye phenomenon (PINHOLE, SAND SURFACE) appears as unplasticized particles on the surface of the molded product, and the gloss of the surface is lowered, thereby lowering the product value of the final molded product.

On the other hand, if it is higher than the above range, rather than reducing the surface adhesive strength when mixing and processing with the matrix SAN resin may result in a decrease in physical properties, resulting in a decrease in physical properties such as impact strength and fluidity and a decrease in natural color.

The graft copolymer latex thus prepared is solidified with 0.5 to 1.5% sulfuric acid aqueous solution, dried to obtain a white powder, and then mixed and processed with a separately prepared SAN resin to provide excellent impact resistance and natural color. To prepare.

In this case, the SAN resin used as the matrix is a SAN resin prepared by a bulk and suspension polymerization method, which is a conventional manufacturing method, and has a weight average molecular weight of 125,000 and an acrylonitrile content of 30% in SAN resin.

In mixing the graft copolymer and the SAN resin, the content of the graft copolymer may be 25 to 50% and the content of the SAN resin may be 75 to 50%, and then, stabilizers and lubricants may be added thereto. .

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited by the following Examples.

Preparation Example 1

One Step Graft Reaction for the Preparation of Primary Graft Copolymer Latex

50.0 parts of butadiene rubbery latex having an average particle diameter of 0.30 µm and a gel content of 78% by weight in a 30 liter reactor equipped with a stirrer, a heating device, a cooling device, a condenser, a monomer and a graft monomer continuous feeding device ) And 140 parts of ion-exchanged water, followed by stirring and dissolving 0.06 parts of 2,2'-azobisisobutylonitrile in 4.50 parts of acrylonitrile and 10.50 parts of styrene in a stirred container. After mixing with 0.03 parts of captan, it is added to the reactor and heated to 50 ° C.

When the temperature of the mixture reaches 50 ° C, the mixture is continued for 30 minutes, and then 0.6 parts of potassium rosinate is added and the reaction is started while stirring and raising the temperature for 10 minutes. When the polymerization temperature reaches 65 ° C, the polymerization is continued for 50 minutes and the polymerization conversion rate is 93. After reaching at least%, the reaction is terminated to prepare a primary graft latex.

Two Step Reaction for the Preparation of Secondary Graft Copolymer Latex

0.30 parts of potassium persulfate was dissolved in 8 parts of ion-exchanged water in the presence of the prepared primary graft latex, and then charged into the reactor, followed by stirring for 10 minutes. 24.50 parts of styrene, 10.50 parts of acrylonitrile and 0.10 part of tertiary dodecyl mercaptan were added to a stirred container, stirred for 10 minutes, and continuously charged at a reactor temperature of 65 ° C. for 3 hours to proceed with the secondary graft reaction.

At this time, when 90 minutes have passed since the monomer mixture is added, 0.2 parts by weight of potassium rosinate as an emulsifier is added in a batch, and when the monomer mixture is added, the reactor temperature is raised to 75 ° C. When the reactor temperature reaches 75 ° C., the reaction is continued for 40 minutes and forcedly cooled. When the reactor temperature reaches 60 ° C., 0.3 parts of 2,2′-methylene-bis (4-methyl-6-t-butyl) phenol, an antioxidant, is added. After the addition, the reaction is terminated.

At this time, the polymerization conversion rate after completion | finish of 1st and 2nd stage polymerization was 97%, and solid content of the obtained latex was 39.2%.

The graft latex was coagulated with 1% sulfuric acid solution, washed, and dried to obtain a white powder.

Manufacturing Examples 2-3

Table 1 shows the method and the measured physical properties of the graft copolymers of Preparation Examples 2 and 3, and the same polymerization conditions as in Preparation Example 1 were applied. It is the same as Example 1 except changing the injection ratio and molecular weight modifier content of the monomer mixture.

Manufacture Comparative Example 1

In the reactor used in Preparation Example 1, 50.0 parts of butadiene rubbery latex having an average particle diameter of 0.30 µm and a gel content of 78% by weight was used in the same rubber polymer as used in Example 1, but 140 parts of ion-exchanged water, 0.6 parts of potassium rosinate, 0.20 parts of sodium pyrophosphate was added to the reactor, followed by stirring, 4.50 parts of acrylonitrile, 10.50 parts of styrene, 0.13 parts of tertiary dedecylmercaptan, and 0.18 parts of cumene hydroperoxide were heated up to 60 ° C., and the mixture temperature was raised to 60 ° C. When reached, the mixture was stirred for 20 minutes, and then 0.35 parts of ferrous sulfate 0.05 part dextrose was added to proceed polymerization for 1 hour.

After completion of the first graft polymerization, 24.50 parts of styrene, 10.50 parts of acrylonitrile and 0.18 parts of tertiary dedecylmercaptan at 70 ° C. were added to a stirred container, stirred for 10 minutes, and continuously added for 3 hours, while 0.25 parts of cumene hydroperoxide was added. It is added continuously over 3 hours to proceed with the secondary graft reaction.

When the monomer and polymerization initiator are added, the reaction is continued for 40 minutes and the reaction is terminated. At this time, the reaction temperature was gradually proceeded to start the second graft reaction at 70 ℃ to 75 ℃, the polymerization conversion after the completion of the polymerization was 97%, the solid content of the latex obtained was 40.9%. The evaluation was measured in the same manner as in Example 1.

Manufacture Comparative Example 2

50.0 parts of butadiene rubbery latex having an average particle diameter of 0.30 µm and a gel content of 78% by weight in the reactor used in Preparation Comparative Example 1, using the same rubbery polymer used in Preparation Example 1, but 140 parts of ion-exchanged water and 0.6 parts of potassium rosinate , 4.50 parts of acrylonitrile, 10.50 parts of styrene, 0.10 parts of tertiary dedecylmercaptan were added thereto, and the temperature was raised to 50 ° C. When the mixture temperature reached 50 ° C, the mixture was stirred for 20 minutes, and then 0.35 parts of potassium persulfate, a water-soluble polymerization initiator, were added thereto. The polymerization was started while the temperature was raised, and the reaction was continued for 30 minutes to prepare the first graft latex, followed by stirring at 70 ° C at 24.50 parts of styrene, 10.50 parts of acrylonitrile, and 0.15 parts of tertiarydecylmercaptan. Put in a container as possible, stirred for 10 minutes, and then continuously added for 3 hours to proceed the secondary graft reaction.

When the addition of the monomer mixture is completed, the reaction is continued for 40 minutes and the reaction is terminated. Subsequent polymerization conditions are the same as in Comparative Preparation Example 1. At this time, the conversion rate after completion of the polymerization was 95%, and the solid content of the obtained latex was 40.1%.

Manufacture Comparative Examples 3-4

As shown in Preparation Comparative Example 1, the graft copolymers of Comparative Examples 3 to 4 and the measured physical properties were shown, and the same polymerization conditions as in Preparation Comparative Example 1 were applied. It is the same as that of the manufacture comparative example 1 except having changed the particle diameter of a polymer.

Preparation Example Comparative Example One 2 3 One 2 3 4 Average particle diameter (㎛) 0.30 0.30 0.30 0.30 0.30 0.38 0.45 % Body weight used in 1,2 graft reaction Primary styrene 10.5 7.0 14.0 10.5 10.5 10.5 10.5 Primary acrylonitrile 4.5 3.0 6.0 4.5 4.5 4.5 4.5 Primary styrene 24.8 28.0 21.0 24.5 24.5 24.5 24.5 Primary acrylonitrile 10.5 12.0 9.0 10.5 10.5 10.5 10.5 Molecular weight regulator amount (weight part) One-step reaction 0.03 0.03 0.03 0.13 0.10 0.10 0.10 Two-step reaction 0.10 0.10 0.10 0.18 0.15 0.18 0.15 Rubber content (solid content,%) 50 50 50 50 50 50 50 Graft Rate (%) Coagulation (%) 62.00.21 56.60.18 58.00.26 65.60.23 51.40.28 59.20.36 53.90.69

Examples 1-3 and Comparative Examples 1-4

Each of the graft copolymers and SAN resins prepared in Preparation Examples 1 to 3 and Comparative Comparative Examples 1 to 4 was added in the amounts shown in Table 2 below, and 0.4 parts by weight of magnesium stearate as stabilizer and ethylene bis stearamide 1.0 After adding and mixing the parts by weight, and extracted by using a twin extruder and injection molding to produce a test piece for measuring the physical properties, the physical properties of the physical properties are shown in Table 2 below.

Example Comparative example One 2 3 One 2 3 4 Graft copolymer content (part) SAN resin content (part) 3070 3070 3070 3070 3070 3070 3070 Notched Izod Impact Strength (1/4 "), ASTM D256 kg Surface condition 1000 × 70 × 3mm, visual observation 30.297.211.676.91.71 ○ 28.696.110.477.11.81 ○ 29.295.310.977.01.78 ○ 22.197.420.571.61.99 ○ 16.798.614.274.92.15 ○ 26.885.719.872.02.05 × 25.981.122.472.32.35 △

* Surface condition: ○: Good, △: Normal, ×: Poor

As described above, the ABS resin manufactured according to the present invention may obtain a thermoplastic resin having improved impact resistance and natural color while maintaining excellent glossiness and fluidity of the ABS resin.

Claims (6)

40-60 parts by weight of rubber latex and styrene having an average particle diameter of 0.25 to 0.34 µm and a gel content of 70 to 90% in preparing the thermoplastic resin by mixing and processing the graft copolymer and the SAN resin. 60 to 40 parts by weight of a graft monomer mixture composed of acrylonitrile is copolymerized inside the rubber with a fat-soluble initiator, and the one-step graft reaction copolymer surrounds the rubber particle surface using a water-soluble pyrolysis initiator. The method of producing a thermoplastic resin having excellent impact resistance and natural color, characterized in that the two-step graft copolymerization reaction. The method of claim 1, wherein the graft reaction is stirred and mixed with 0.03 to 0.15 parts by weight of a fat-soluble pyrolysis polymerization initiator in the presence of 40 to 60 parts by weight of a rubbery polymer, followed by adding a molecular weight regulator and ion exchanged water and then stirring While the temperature is raised to 40 to 50 ° C., the stirring is continued for 10 to 40 minutes so that the first-grafted graft monomer is swollen into most of the rubber particles, and then an emulsifier is added to increase the temperature of the reactor to initiate polymerization. When the internal temperature of the temperature reaches 60 ~ 75 ℃ to maintain the internal temperature of the reactor at 60 ~ 75 ℃ using a cooler, and then the reaction is continued for 30 to 60 minutes, the polymerization resistance characterized in that the polymerization conversion of 93% or more And a thermoplastic resin having excellent natural color. The method of claim 1, wherein the two-step graft reaction is added 0.20 to 0.50 parts by weight of a water-soluble pyrolysis initiator in the reactor in the presence of the primary graft copolymer latex prepared by the first step reaction and stirred for 5 to 15 minutes 90 to 60% of the graft monomer mixture and the molecular weight modifier were mixed and stirred, followed by continuous dosing for 2 to 5 hours to allow a small amount of graft monomers to participate in the graft reaction at a constant rate. A method for producing a thermoplastic resin having excellent impact resistance and natural color, wherein a small amount of emulsifier is added at a time after 30 hours from 30 minutes after the continuous dosing of monomers. The method of claim 2, wherein the fat-soluble pyrolysis polymerization initiator used in the one-step graft polymerization is 2,2'-azobisisobutylonitrile. 4. The method of claim 3, wherein the water-soluble pyrolysis polymerization initiator used in the two-step graft reaction is potassium persulfate. The method for producing a thermoplastic resin having excellent impact resistance and natural color according to claim 1, wherein the graft ratio of the graft copolymer is 40 to 65%.