KR100998368B1 - Method for preparing acrylonitrile-butadiene-styrene based copolymer latex - Google Patents

Abstract

The present invention relates to a method for producing acrylonitrile-butadiene-styrene (ABS) copolymer latex, and the method for producing ABS copolymer latex by graft polymerization of polybutadiene rubber latex, aromatic vinyl compound monomer and vinyl cyan compound monomer. In the method of manufacturing, i) the polybutadiene rubber latex is characterized in that one is produced by fusing a small diameter polybutadiene rubber latex, ii) methyl methacrylate and the like during the graft polymerization reaction It is another feature that the monomer is added while the input mass is increased with time. The production method according to the invention has the advantage that the polymerization conversion rate of the monomer is high, the amount of unreacted monomer and the third monomer to be introduced is reduced, the polymerization productivity is high, and environmentally friendly.

Acrylonitrile-butadiene-styrene, latex, emulsion polymerization, acid, fusion, tertiary monomer, polymerization conversion, productivity, environmental friendliness

Description

Production method of acrylonitrile-butadiene-styrene copolymer latex {METHOD FOR PREPARING ACRYLONITRILE-BUTADIENE-STYRENE BASED COPOLYMER LATEX}

The present invention relates to a method for producing an acrylonitrile-butadiene-styrene type (ABS type) copolymerized latex, and more particularly, in the polymerization of ABS-based latex, acrylonitrile, which is a monomer, The present invention relates to a method for producing an acrylonitrile-butadiene-styrene copolymer latex which is economical and environmentally friendly by increasing the polymerization conversion ratio of butadiene and styrene to reduce the residual amount of monomer.

In general, acrylonitrile-butadiene-styrene (ABS) -based copolymer resins have been applied to various fields because of excellent physical properties such as impact resistance, chemical resistance, processability, and surface gloss. The production method of acrylonitrile-butadiene-styrene resin includes a step of preparing polybutadiene rubber latex serving as a seed and an emulsion polymerization step of grafting acrylonitrile and styrene onto polybutadiene rubber latex. It is done by

As a method for producing a large-diameter rubber latex, a method of manufacturing a large-diameter rubber latex is a method of fusion of particles by lowering the pH by adding an acidic substance such as acetic acid or phosphoric acid to a rubber latex having a small diameter particle diameter (Japanese Patent Laid-Open). No. 63-132903, No. 63-117005, No. 2-9601, No. 55-19246, No. 42-3112, No. 7-157501, Korean patent application 1998-9632).

In the early stages of research on ABS emulsion polymerization, much emphasis was placed on increasing production facilities, but as the prices of acrylonitrile, butadiene and styrene, which are the raw materials for ABS, increased, the reduction of residual monomers and the improvement of productivity, etc. Cost-saving efforts are underway. In particular, the reduction of residual monomers in ABS latex not only contributes to cost reduction, but also becomes an important criterion for environmental regulations that are recently strengthened. Residual monomers in the manufacture of ABS latex can be released into the water and air during the process, and may involve emissions of total volatile organic compounds (TVOC) from the appearance of finished vehicles and appliances. With the recent tightening of environmental regulations for water pollution and air pollution, the reduction of residual monomers has become more important.

As a method for reducing the residual monomers presented so far, in the emulsion polymerization using rubber particles having a low crosslinking degree, the conversion rate of monomers at the end of the reaction is higher than 98% and the conversion rate is increased through the input of a third monomer (WO No. O3 / 010214, U.S. Patent No. 6,784,253, U.S. Patent Nos. 4,272,425, and 4,822,858), respectively, in which additional monomers such as butadiene and acrylonitrile are added to increase the conversion rate. However, the above method is not clear the role of the third monomer to be added at the end of the reaction, there is a problem that the third monomer remains after the reaction.

Accordingly, an object of the present invention is to provide a method for producing acrylonitrile-butadiene-styrene copolymer latex having high polymerization conversion rate.

Another object of the present invention is to reduce the amount of unreacted monomers and third monomers to be introduced, to increase polymerization productivity, and to prevent environmental pollution, and to provide high polymerization conversion of acrylonitrile-butadiene-styrene copolymer latex. It is to provide a manufacturing method.

In order to achieve the above object,

The present invention comprises the steps of: a) emulsion-polymerizing butadiene to produce polybutadiene rubber latex of small diameter;

b) fusion of the prepared small-diameter polybutadiene rubber latex to produce a large-diameter polybutadiene rubber latex;

c) i) Injecting the prepared large diameter polybutadiene rubber latex into the reactor, ii) adding an aromatic vinyl compound monomer, a vinyl cyanide monomer, a third monomer, an initiator and an emulsifier. To increase according to the step, performing the emulsion polymerization;

It provides a method of producing an acrylonitrile-butadiene-styrene copolymer latex comprising a.

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

In order to prepare a high conversion acrylonitrile-butadiene-styrene-based copolymer latex according to the present invention, first, a) polybutadiene rubber latex is prepared by emulsion polymerization of butadiene.

This step is performed by a variety of known emulsion polymerization methods, including conventional emulsion polymerization method, for example, the rubber latex production method disclosed in Korean Patent Publication No. 1999-0075431 (Korean Patent Application No. 10-1998-0009632) Can be.

The method for producing small-diameter rubber latex disclosed in the Republic of Korea Patent Publication No. 10-1999-0075431 (Korean Patent Application No. 10-1998-0009632) is 50 to 95 parts by weight before the start of polymerization in a total of 100 parts by weight of butadiene monomer After the reaction for a predetermined time, the remaining butadiene monomer 50 to 5 parts by weight in a batch or continuous (sequential) administration to increase the gel content of the small-diameter rubber latex and to lower the outer gel dilution, the particle size through the subsequent acid flocculation step This large and narrow distribution ABS-based copolymer latex has the advantage that can be produced.

Butadiene includes 1,3-butadiene, isoprene, chloroprene, pyrrylene, and the like, and comonomers thereof are also possible. In addition, it can be used in combination with a vinyl cyan compound, such as styrene, a vinyl styrene, such as styrene, α-methyl styrene copolymerized with acrylonitrile, etc., it is preferable to use within 20 parts by weight of the total monomer mixture.

As an emulsifier, an emulsifier which can be used conventionally can be used, but can be, but is not limited to, alkyl aryl sulfonate, alkali methyl alkyl sulfate, sulfonated alkyl ester, soap of fatty acid, alkali salt of rosin acid, or a mixture thereof. have.

As the polymerization initiator, a conventionally available polymerization initiator may be used, but may be, but are not limited to, a water-soluble persulfate, a peroxy compound, a redox-based initiator, or a mixture thereof, and the water-soluble persulfide may be sodium and potassium persulfide. As the fat-soluble polymerization initiator, cumene hydroperoxide, diisopropyl benzene hydroperoxide, azobis isobutylonitrile, tertiary butyl hydroperoxide, paramethane hydroperoxide, benzoyl peroxide or mixtures thereof are preferable.

As the electrolyte, a conventionally available electrolyte can be used, but is not limited to KCl, NaCl, KHCO ₃ , NaHCO ₃ , K ₂ CO ₃ , Na ₂ CO ₃ , KHSO ₃ , NaHSO ₃ , K ₄ P ₂ O ₇ , Na ₄ P ₂ O ₇ , K ₃ PO ₄ , Na ₃ PO ₄ , K ₂ HPO ₄ , Na ₂ HPO _4, or a mixture thereof.

As a molecular weight regulator, a molecular weight regulator which can be used can be used conventionally, and it can be a mercaptan compound, such as a non-limiting thing, dodecyl mercaptan.

The reaction temperature of this step is determined in consideration of the reaction rate, the boiling point of the reaction solvent, for example, may be 50 to 70 ℃, the reaction pressure is determined in consideration of the reaction temperature, the boiling point of the reaction solvent, etc. For example, it may be 5 to 7 atm, the reaction time is not particularly limited, and is determined in consideration of the reaction yield and economics, for example, may be 3 to 15 hours.

For example, the average particle diameter of the small-diameter rubber latex obtained through this step may be 700 kPa to 1500 kPa, the particle size distribution is 25% or less, the gel content is 70 to 99, the swelling index may be 16 to 40. However, the physical properties of the small-diameter rubber latex is just one example of the rubber latex obtained through this step, but is not limited thereto.

Next, b) fusion of the prepared small-diameter polybutadiene rubber latex is performed to prepare a large-diameter polybutadiene rubber latex.

This step can be carried out under acidic conditions, the acidic conditions can be formed by adding acids such as acetic anhydride, phosphoric acid, sulfuric acid, hydrochloric acid, and the pH is preferably 2 to 6, more preferably 3 to 5. .

Temperature and pressure in this step are not specifically limited, For example, normal temperature and normal pressure.

In the case of producing a large diameter latex by agglomerating a small diameter latex under acidic conditions by adjusting the concentration and amount of acid according to this step, the rubber latex prepared by acid agglomeration includes relatively unaggregated small particles. Due to this, the reaction rate is increased to reduce the total residual amount of the monomer.

Next, c) i) a large diameter polybutadiene rubber latex prepared in the reactor, and ii) an aromatic vinyl compound monomer, a vinyl cyanide monomer, a third monomer, an initiator and an emulsifier, The input mass is added to increase with time, and the emulsion polymerization is performed.

Examples of the aromatic vinyl compound monomer include, but are not limited to, styrene, alpha methyl styrene, paramethyl styrene, or a mixture thereof. Preferably, styrene may be used. The amount of the aromatic vinyl compound added may be, for example, 65 to 80 parts by weight based on 100 parts by weight of the total amount of the monomers and the third monomer. When out of the above range, a homopolymer is produced, or the ABS resin latex powder obtained by agglomeration, washing and drying the ABS latex is compounded with another polymer resin such as styrene-acrylonitrile (SAN). There is a fear that compatibility may decrease.

Examples of the vinyl cyanide monomer include, but are not limited to, acrylonitrile, methacrylonitrile, ethacrylonitrile, or a mixture thereof, preferably acrylonitrile. The amount of the vinyl cyanide monomer added may be, for example, 15 to 30 parts by weight based on 100 parts by weight of the total amount of the monomer and the third monomer. If it exceeds the above range, there is a problem in thermal stability. In this step, the third monomer means a monomer except the monomer of the present invention, which is an aromatic vinyl compound, and a monomer of the present invention, which is a vinyl cyan compound, and such a third monomer serves to reduce the total residual amount of the monomer. . The present invention not only reduces the total amount of the monomer remaining after the reaction by changing the method of adding the third monomer, but also reduces the amount of the unreacted third monomer.

The input mass of the third monomer is added to increase with time, for example, the third monomer may be added such that when the batch is added in a batch, the mass of the third monomer to be added is gradually increased. , Ii) In the case of continuously divided input, the mass of the divided third monomer may be added to increase stepwise or continuously with time, and other various amounts of the third monomer added to increase with time It can be put in the way.

The third monomer may be added as iii) a monomer alone, or ii) as a mixed solution in an emulsified state including a monomer, an initiator, an emulsifier, and a third monomer. It can be added in a mixed state with these reactants without limiting the type, content of the reactants in the step of the emulsification step. In the case of ii), for example, a plurality of mixtures of an emulsified state having different masses of the third monomer are produced in the same amount, respectively, and the mixtures are successively fed at the same dosage rate from the mixed solution having a lower mass of the third monomer. Can be added (see Example 1 below).

Tertiary monomers include, but are not limited to methyl methacrylate, methyl acrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, 2-ethyl hexyl acrylate, benzyl acrylate, isopropyl acrylate or mixtures thereof And methyl methacrylate may be preferably used.

The amount of the third monomer added may be, for example, 1 to 5 parts by weight based on 100 parts by weight of the total amount of the monomers and the third monomer. If it is less than the above range, there is a problem that the effect of the third monomer may not appear, and if it exceeds the above range, there is a problem that the residual monomer increases.

As the initiator, a compound of the same kind as the initiator that can be used in the small-diameter rubber latex manufacturing step of the present invention may be used, and the amount of the initiator is determined in consideration of the reaction yield and the physical properties of the prepared ABS-based latex, for example 0.1 to 1 part by weight based on 100 parts by weight of the total amount of the monomers and the third monomer.

The emulsifier may be a compound of the same kind as the emulsifier that can be used in the small-diameter rubber latex manufacturing step of the present invention, the amount of the emulsifier may be 1 to 5 parts by weight based on 100 parts by weight of the total amount of the monomer and the third monomer. have.

This step may also use additives such as molecular weight regulators and electrolytes that can be used in the small diameter rubber latex production step of the present invention, and other starting aids such as ferrous sulfate and sodium pyrrolate. The trivalent ferrous sulfate serves to decompose an initiator such as cumene hydroperoxide to have a radical while being reduced to divalent so as to start radical polymerization through the initiator, and sodium pyrolate is a chelating agent. As a result, it forms a water-soluble salt with ferrous sulfate and maintains a state of solvating iron ions, thereby preventing ferrous sulfate from directly reacting with an initiator such as cumene hydroperoxide. .

This step can be carried out by a variety of known emulsion polymerization methods, including conventional emulsion polymerization method, for example, the step of adding a large diameter rubber latex, ion exchange water, emulsifier to a nitrogen-substituted polymerization reactor monomer, initiator, molecular weight Initiating the polymerization reaction by adding the regulator, ion-exchanged water, etc. collectively, the process comprising the step of adding the third monomer to the reactor to increase the mass, and the step of maintaining the temperature after raising the temperature of the reactor It can be performed as.

The reaction product polymerized in the above step is obtained with acrylonitrile-butadiene-styrene copolymer latex, and the copolymer latex means a state in which acrylonitrile-butadiene-styrene copolymer latex particles are dispersed in a solvent such as water. The copolymer latex is obtained as an acrylonitrile-butadiene-styrene copolymer latex powder by performing a conventional method, for example, a conventional flocculation and drying process. As the flocculant, a known flocculant may be used, including but not limited to a commonly used flocculant, without limitation, sulfuric acid, magnesium sulfate (MgSO ₄ ), calcium chloride (CaCl ₂ ), aluminum sulfate (Al ₂ (SO) ₄ ) or Mixtures of these can be used.

The latex powder prepared according to the present invention may be mixed with a styrene resin and processed into an ABS resin composition which is a final product. As the styrene resin, various styrene resins prepared by bulk polymerization or solution polymerization may be used. For example, SAN resins prepared by solution polymerization may be used. The content of the ABS copolymer latex powder is, for example, 10 to 40% by weight based on the entire ABS resin composition.

Acrylonitrile-butadiene-styrene-based latex production method according to the present invention has a high polymerization conversion rate of the monomer, reducing the amount of unreacted monomer and the third monomer introduced, high polymerization productivity, environmentally friendly .

Next, the present invention will be described in more detail with reference to Examples. However, the following examples are only for illustrating the present invention more specifically, the present invention is not limited by the following examples.

Example 1

Small Diameter Rubber Latex Manufacturing Process

110 parts by weight of ion-exchanged water, 85 parts by weight of 1,3-butadiene as monomer, 1.2 parts by weight of potassium rosin salt as emulsifier, 1.5 parts by weight of potassium oleate salt, sodium carbonate as electrolyte ₂ CO ₃ ) 0.1 parts by weight, 0.5 parts by weight of potassium hydrogen carbonate (KHCO ₃ ), 0.3 parts by weight of tertiary dodecyl mercaptan (TDDM) as the molecular weight regulator, 0.3 parts by weight of potassium persulfate as the initiator and the reaction temperature 55 ℃ , The reaction was carried out at 5 atmospheres for 10 hours, and then 15 parts by weight of the remaining monomers 1,3-butadiene and 0.05 parts by weight of tertiary dodecyl mercaptan were added in a batch, and the reaction was performed at 65 ° C and 6 atmospheres for 8 hours. Small diameter rubber latex was prepared.

Small Diameter Rubber Latex Fusion Process

100 parts by weight of the prepared small-diameter rubber latex was added to the reactor, the stirring speed was adjusted to 10 rpm, the temperature was adjusted to 30 ° C., and 3.5 parts by weight of 10% acetic acid aqueous solution was continuously added for 1 hour. Next, after stopping the stirring, the mixture was left for 30 minutes, and a small diameter rubber latex was fused to prepare a large diameter rubber latex.

The particle size and particle distribution were measured using Nicomp 370HPL by dynamic laser light scattering method. The measured particle size was 3000Å, gel content was 85%, and swelling index was 17. The gel content and swelling index were calculated by the following equation.

Gel content (%) = weight of insolubles (gel) / weight of sample X 100

Swelling index = weight of swollen gel / weight of gel

ABS graft step

Step 1: 60 parts by weight of large-diameter rubber latex (particle diameter 3000Å, gel content 85%, swelling index 17) prepared by fusion process in nitrogen-substituted polymerization reactor, 80 parts by weight of ion-exchanged water, and 0.5 parts by weight of Rosin soap were added.

Step 2: After raising the temperature inside the reactor to 50 ° C, 2.5 parts by weight of acrylonitrile, 7.5 parts by weight of styrene, 0.04 parts by weight of cumene hydroperoxide, 0.08 parts by weight of dextrose, 5 parts by weight of ion-exchanged water, pyrrole 0.006 parts by weight of sodium phosphate and 0.001 parts by weight of ferrous sulfate were collectively added to initiate the polymerization reaction.

Step 3: The emulsion (A ~ C) consisting of the following components were prepared in a separate mixing device, and then the emulsions A, B, and C prepared immediately after the start of the reaction were continuously added to the reactor for a total of 3 hours for 1 hour. It was. The reaction temperature was raised to 72 ℃ for 1 hour as the emulsion was continuously added after the start of the reaction, and then maintained constant for 2 hours.

Emulsion A. 2.4 parts by weight of acrylonitrile, 7.2 parts by weight of styrene, 0.4 parts by weight of methyl methacrylate, 0.1 part by weight of tertiary dodecyl mercaptan, 0.5 part by weight of cumene hydroperoxide, 0.2 part by weight of Rosin soap, ion exchange water 3 parts by weight

Emulsion B. 2.3 parts by weight of acrylonitrile, 6.9 parts by weight of styrene, 0.8 parts by weight of methyl methacrylate, 0.1 part by weight of tertiary dodecyl mercaptan, 0.5 part by weight of cumene hydroperoxide, 0.2 part by weight of Rosin soap, ion exchange water 3 parts by weight

Emulsified core C. 2.2 parts by weight of acrylonitrile, 6.6 parts by weight of styrene, 1.2 parts by weight of methyl methacrylate, 0.1 parts by weight of tertiary dodecyl mercaptan, 0.5 parts by weight of cumene hydroperoxide, 0.2 parts by weight of Rosin soap, ion exchange 3 parts by weight

Step 4: After the addition of the reaction mixture, 0.03 part by weight of dextrose, 0.02 part by weight of sodium pyrolate, 0.0006 part by weight of ferrous sulfate, and 0.05 part by weight of cumene hydroperoxide were added and the temperature was increased to 80 ° C. for 40 minutes. The temperature was raised to then the reaction was terminated.

After completion of the reaction, the polymerization conversion rate of ABS copolymer latex, the residual amount of unreacted monomer and the residual amount of unreacted methyl methacrylate were measured and shown in Table 1 below.

Comparative Example 1

Steps 1 and 2 were performed in the same manner as in Example 1.

Step 3: Methyl methacryl with 6.9 parts by weight of acrylonitrile, 20.7 parts by weight of styrene, 0.3 parts by weight of tertiary dodecyl mercaptan, 1.5 parts by weight of cumene hydroperoxide, 0.6 parts by weight of Rosin soap, 9 parts by weight of ion-exchanged water 2.4 parts by weight of the mixture was mixed to form an emulsion in which the monomer was stably dispersed, and continuously added.

Next, the emulsion prepared immediately after the start of the reaction was continuously added to the reactor over a total of 3 hours. The reaction temperature was raised to 72 ℃ for 1 hour while the emulsion was continuously added after the start of the reaction, and then maintained constant for 2 hours.

Step 4: The same method as in Example 1 was performed.

After completion of the reaction, the polymerization conversion rate of ABS copolymer latex, the residual amount of unreacted monomer and the residual amount of unreacted methyl methacrylate were measured and shown in Table 1 below.

Comparative Example 2

Manufacture of Large Diameter Rubber Polymers by Direct Polymerization

75 parts by weight of ion-exchanged water in a nitrogen-substituted polymerization reactor (autoclave), 80 parts by weight of 1,3-butadiene as monomer, 1.2 parts by weight of potassium rosin salt as emulsifier, 1.5 parts by weight of potassium oleate salt, sodium carbonate (Na2CO3 as electrolyte) ) 0.7 parts by weight, 0.8 parts by weight of potassium hydrogen carbonate (KHCO3), 0.3 parts by weight of tertiary dodecyl mercaptan (TDDM) as the molecular weight regulator, 0.3 parts by weight of potassium persulfate as the initiator, and the reaction temperature for 70 hours at 70 ℃ After the reaction, 20 parts by weight of the remaining monomers 1,3-butadiene and 0.05 parts by weight of tertiary dodecyl mercaptan were collectively added and reacted at 75 ° C. for 28 hours, and then the reaction was completed.

The particle size and particle size distribution were measured using a Nicomp 370HPL by the dynamic laser light scattering method. As a result, the particle size was 3000Å, gel content 69%, and swelling index 24. The gel content and swelling index were calculated by the following equation.

Gel content (%) = weight of insolubles (gel) / weight of sample * 100

Swelling index = weight of swollen gel / weight of gel

ABS graft step

ABS copolymer latex was prepared in the same manner as in Example 1, except that the large-diameter rubber latex (particle diameter 3000Å, gel content 69%, swelling index 24) was used as the large-diameter rubber latex. The polymerization conversion rate of ABS copolymer latex, the residual amount of unreacted monomer, and the residual amount of unreacted methyl methacrylate were measured and shown in Table 1 below.

Comparative Example 3

ABS copolymer latex was prepared by the same method as Comparative Example 1, except that the large-diameter rubber latex (particle diameter 3000Å, gel content 69%, swelling index 24) was used as the large-diameter rubber latex. The polymerization conversion rate, residual amount of unreacted monomer, and residual amount of unreacted methyl methacrylate of the prepared ABS copolymer latex were measured and shown in Table 1 below.

[Comparative Example 4]

Step 1: 60 parts by weight of the large-diameter rubber latex (particle diameter 3000 중, gel content 69%, swelling index 24) prepared by the direct polymerization method of Comparative Example 2, 90 parts by weight of ion-exchanged water, 0.5 parts by weight of Rosin soap.

Step 2: The same procedure as in Example 1 was performed.

Step 3: The monomer is stabilized by mixing 7.5 parts by weight of acrylonitrile, 22.5 parts by weight of styrene, 0.3 parts by weight of tertiary dodecyl mercaptan, 1.5 parts by weight of cumene hydroperoxide, 0.6 parts by weight of Rosin soap, and 9 parts by weight of ion-exchanged water. Easily dispersed emulsion was made and continuously added for 3 hours.

The reaction temperature was raised to 72 ℃ for 1 hour while the emulsion was continuously added after the start of the reaction, and then maintained constant for 2 hours.

Step 4: The same method as in Example 1 was performed.

[Comparative Example 5]

ABS copolymer latex was prepared in the same manner as in Comparative Example 4, except that the large-diameter rubber latex (particle diameter 3000 으로, gel content 69%, swelling index 24) prepared by the fusion method of Example 1 was used. The polymerization conversion rate of the copolymerized latex, the residual amount of the unreacted monomer, and the residual amount of the unreacted methyl methacrylate were measured and shown in Table 1 below.

As shown in Table 1, Example 1 compared to Comparative Examples 1 to 5, the polymerization conversion rate of the monomer was higher, the total residual amount of the monomer and the content of unreacted methyl methacrylate was confirmed to be low.

Acrylonitrile-butadiene-styrene-based latex production method according to the present invention has a high polymerization conversion rate of the monomer, the amount of the unreacted monomer and the third monomer introduced is reduced, the polymerization productivity is high, and there is an environment-friendly .

Claims (6)

a) emulsion-polymerizing butadiene to produce polybutadiene rubber latex having a small diameter; b) fusion of the prepared small-diameter polybutadiene rubber latex to produce a large-diameter polybutadiene rubber latex; And c) iii) adding the prepared large diameter polybutadiene rubber latex to the reactor, and ii) adding an aromatic vinyl compound monomer, a vinyl cyanide monomer, a third monomer, an initiator and an emulsifier, wherein the third monomer is methyl meta. Selected from the group consisting of acrylate, methyl acrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, 2-ethyl hexyl acrylate, benzyl acrylate, isopropyl acrylate and mixtures thereof; The monomer input mass is added to increase with time, performing emulsion polymerization; Consisting of, Method for producing acrylonitrile-butadiene-styrene copolymer latex. The method of claim 1, b) preparing the large diameter polybutadiene rubber latex is characterized in that it is carried out in acidic conditions Method for producing acrylonitrile-butadiene-styrene copolymer latex. delete The method of claim 1, The aromatic vinyl compound monomer is styrene, the vinyl cyan compound monomer is acrylonitrile, and the third monomer is methyl methacrylate. Method for producing acrylonitrile-butadiene-styrene copolymer latex. The method of claim 1, The method of adding the third monomer may include: i) a method of dividing into a batch, and adding a mass of the third monomer to be divided into gradually increasing, or ii) continuously adding and dividing to a third monomer. The mass of is characterized in that the method is added to increase stepwise or continuously with time Method for producing acrylonitrile-butadiene-styrene copolymer latex. The method of claim 1, In the method of adding the third monomer, a plurality of mixed solutions in an emulsified state including a monomer, an initiator, an emulsifier, and a third monomer are prepared in the same amount, respectively, and the mass of the third monomer is sequentially reduced from the mixed solution having a low mass. Characterized in that it is a method of continuously adding the mixed liquid at the same input speed Method for producing acrylonitrile-butadiene-styrene copolymer latex.