KR0181558B1 - Process for preparation of polybutadiene latex - Google Patents

Abstract

The present invention aims to produce a high concentration of polybutadiene latex having a number average particle diameter of at least 2000 μs or more in a relatively short time to improve productivity, and at the same time provide a polymer particle size and a high concentration of stable polybutadiene latex which are very suitable for the production of ABS graft copolymers. Regarding the production method of polybutadiene to

(1) Aqueous emulsions of butadiene containing water having a monomer / water weight ratio of 1.0 to 1.4 and an anionic emulsifier and an electrolyte / emulsifier having a weight ratio of 0.6-0.9 to a butadiene monomer and a chain transfer regulator are prepared. After entering the reactor,

(2) raising the reaction temperature and adding a free radical initiator to start and proceed polymerization;

(3) When the conversion rate is more than 50%, an anionic or nonionic emulsifier is continuously added,

(4) after the reaction is completed, characterized in that the process consisting of recovering the unreacted monomer of polybutadiene latex.

Description

How to prepare polybutadiene latex (POLYBUTADIENE LATEX)

The present invention relates to a method for producing polybutadiene latex, and more particularly, to a method for producing polybutadiene latex suitable for producing acrylonitrile / butadiene / styrene grafted copolymer (hereinafter referred to as ABS resin).

In general, polybutadiene latex is prepared by an emulsion polymerization method using about 3 to 5 parts by weight of an emulsifier with respect to 100 parts by weight of butadiene at a relatively low temperature of 40 ℃ to 70 ℃.

The polybutadiene latex produced by this emulsion polymerization method converts about 70% by weight of the monomer into the polymer in about 20 hours or more. In this case, the number average particle diameter of the polybutadiene latex particles does not exceed 1000 mm 3. However, polybutadiene latex having such a particle diameter is not suitable for many applications including the production of ABS graft copolymers requiring polybutadiene latex having a number average particle diameter of at least 2000 mm 3 and a weight average particle diameter of 2500 mm 2. Especially in the case of ABS graft copolymer, when the number average particle diameter of polybutadiene latex is less than 2000 micrometers or the average weight particle diameter is less than 2500 micrometers, the IZOD impact strength of the final ABS molded product becomes very weak.

On the other hand, it is well known that the average particle size of the latex particles increases when the amount of reducing agent in the emulsion polymerization decreases. In addition, it is well known that an increase in the reaction temperature of the emulsion polymerization increases the polymerization rate, thereby increasing the polymerization time but decreasing the average particle diameter of the polybutadiene latex particles.

Therefore, conventionally, as a method for obtaining the desired large number average particle size, a method of reducing the emulsifier concentration while maintaining the polymerization temperature described above is used. However, this method has a disadvantage in that the polymerization time is very long. For example, a polymerization reaction using less than 2.0 parts by weight of an emulsifier with respect to 100 parts by weight of butadiene requires a long reaction time of 60 hours or more, and also increases the stability of the polybutadiene latex during polymerization in proportion to the decrease in the concentration of the emulsifier. There is a problem of deterioration and generation of coagulum.

Therefore, the present invention solves the problems in the conventional method, and minimizes the amount of emulsifier at the beginning to produce a high concentration (more than 45% by weight solid) polybutadiene latex having a number average particle size of at least 2000 kPa in a relatively short time to improve productivity At the same time, it aims to provide a polymer particle diameter and a high concentration of stable polybutadiene latex which is very suitable for the production of ABS graft copolymers.

As a result of intensive research to achieve the above object, the present inventors have found that the above object can be achieved by adjusting the concentration of the electrolyte / emulsifier and the concentration of the monomer / water in the emulsion polymerization. Was done.

That is, the present invention has a number average particle diameter (Dn) of at least 2000 kPa and a weight average particle diameter (Dw) of at least 2500 kPa, and in the preparation of rubbery polybutadiene latex having a total solid content of 45 wt% or more,

(1) An aqueous emulsion of butadiene containing water having a monomer / water weight ratio of 1.0-1.4 to an butadiene monomer, and an electrolyte having a weight ratio of 1.2 to 2.2 parts by weight of an anionic emulsifier and an electrolyte / emulsifier of 0.6-0.9 and a chain transfer regulator. After preparing (OIL IN WATE) solution and putting it in the high pressure reactor,

(2) Initiate the polymerization by raising the reaction temperature and introducing a pyrolysable glass initiator, and proceed the polymerization under the condition that the polymerization reaction temperature is 60-80 ° C. Situation)

(3) 1 to 3 parts by weight of anionic or nonionic emulsifiers are continuously added to improve the stability of the reaction mixture at a suitable time when the conversion ratio is 50% or more;

(4) When the reaction is completed, the polybutadiene latex is transferred to an unreacted monomer recovery tank (RECOVERY TANK), and the process of producing a desired polybutadiene latex by recovering the unreacted monomer.

Hereinafter, the present invention will be described in detail.

The method of the present invention is a particularly useful method for the production of polybutadiene latex used for the production of ABS resin, and it is most important to adjust the monomer / water concentration ratio, the electrolyte / emulsifier concentration ratio, the reaction temperature and the like to an optimum state.

The emulsifier used in the method of the present invention is not particularly limited, but an emulsifier used in ordinary emulsion polymerization can be used. Examples include anionic emulsifiers such as sodium lauryl sulfate, sodium octyl sulfate, sodium dodecylbenzene sulfonate, sodium toluene sulfonate, potassium stearyl phosphate, potassium stearate, potassium rosinate and sodium rosinate, ethylene glycol stearate, poly There are nonionic emulsifiers such as oxyethylene nonylphenyl ester and octyl wasteoxypolyethyloxyethanol, and these may be used alone or in combination. However, considering the size, yield and economic efficiency of the resulting particles, anionic emulsifiers may be used at the initial stage of polymerization. It is preferable to use alone and to use these alone or in combination after the middle of polymerization.

In addition, in the method of the present invention, pyrolytic glass group initiators, which are initiators that generate free groups by pyrolysis, are preferably used. Preferably, an initiator having a half-life of less than 1 minute at 100 to 200 ° C is preferably used.

Such initiators include potassium persulfate, magnesium persulfate and benzoyl peroxide, hydrogen peroxide and the like. Even more preferably it should be an initiator that is not water soluble or fat soluble, such as sodium sulfate, ammonium persulfate. Since they have a relatively fast half-life above 70 ° C, they decompose relatively quickly and participate in the reaction. The amount of free radical initiator to be used is generally 0.1 to 0.5 parts by weight, more preferably 0.2 to 0.35 parts by weight.

Chain transfer regulators used to adjust the gel content of the polybutadiene latex produced in the present invention, such as n-octyl mercaptan, t-dodecyl mercaptan, n-dodecyl mercaptan and mercaptan ethanol or the like Mercaptans, halogenated hydrocarbons such as terpin and chloroform and carbon tetrachloride, α-methylstyrene dimer, terpinolene and the like can be used, and these can be used alone or in combination of two or more thereof. And the usual amount of use is 0.1-1.0 parts by weight.

The gel content is usually 60-90% by weight but more preferably 70-85% by weight. When the gel content is less than 70% by weight, the impact strength and gloss of the ABS resin are lowered, and when the gel content is more than 85% by weight, the appearance of the ABS molded product is poor. Even more preferably, it is preferable to use 0.2 to 0.5 parts by weight of the chain transfer regulator.

In addition, when oxygen is present during the polymerization reaction, oxygen has an inhibitory effect on the polymerization reaction, and thus, when 0.01 to 0.03 parts by weight of an oxygen scavenger (SOCAUM HYDROSULFITE) is contained, it is advantageous to shorten the polymerization time. Done.

In general, a small amount of an electrolyte such as anhydrous potassium carbonate, potassium chloride, tetrasodium pyrophosphate, and sodium sulfate is added in a small amount of 0.5 to 2.0% by weight to control the number of micelles in the initial stage of polymerization. Adjust the average particle size. In the present invention, in order to achieve the invention effect more effectively, the amount of the aforementioned anionic emulsifier and the aforementioned electrolyte should be controlled. For example, the initial weight ratio of anhydrous potassium carbonate / sodium rosin should be 0.6 to 0.9. If their ratio is less than 0.6, the number average particle diameter (Dn) will be less than 2000Å, and if it exceeds 0.9, the coagulation area during polymerization Agglomeration effect in (AGGLOMERATION ZONE) is increased, the weight average particle diameter (Dw) is more than 3500Å, the stability of the latex is reduced, a large amount of coagulant is generated, and the polymerization time is very long.

In addition, the ratio of monomer to water or phase ratio (PHASE RATIO) varies depending on the total solid content of the final latex, but in order to obtain the desired high concentration latex and the desired particle size, the ratio (monomer / water) of 1.0 to 1.4 weight ratio. This ratio is adjusted in response to the demand of the optimum latex particle size and the like in the reaction rate to be accommodated.

In general, according to the theory of emulsion polymerization, it is reported that the ratio of monomer / water does not affect the reaction rate, but in practice, when the amount of water to monomer increases, solubilization of emulsifier to water increases, and the initial number of reaction micelles (MECELL) is increased. This increases the average particle size of the final latex and shortens the polymerization time. Therefore, in order to obtain a high concentration of polybutadiene latex and a latex having a number average particle diameter of 2000 kPa or more, the ratio of monomer / water is very important.

Hereinafter, the present invention will be described through Examples and Comparative Examples, but the present invention is not limited thereto. In addition, all the parts and percentages in the following examples and comparative examples are based on weight unless otherwise indicated.

Example 1

The ion-exchanged water was added to the 200 l high pressure reactor (designed at a pressure of 20 kgf / cm 2) equipped with a device capable of continuously adding a stirrer, a heating device, a cooling device, a monomer, and a polymerization initiator. , 80, 90, 100 parts, 0.3 parts of t-dodecyl mercaptan, 1.3 parts of anhydrous potassium carbonate, 1.8 parts of sodium rosinate, 0.02 parts of sodium hydrosulfite, mixed for 1 hour, followed by three nitrogen purges and vacuum In a vacuum, 100 parts of butadiene were added and stirred and the temperature was raised. When the temperature of the reactor reached 70 ° C, 0.4 parts of dissolved potassium persulfate was added to start the reaction, and the polymerization rate and average particle diameter were measured at 2 hour intervals. In addition, when the polymerization rate reached 65%, 2.5 parts of sodium rotate was continuously added until the polymerization was completed to improve the stability of the latex and to promote the polymerization.

The number average and weight average particle diameter of the latex thus obtained were measured by MATEC CHDF 1100 (PARTICLE SIZE ANALYZER). In addition, the gel content of the polybutadiene latex was measured by filtration and drying the polymer particles obtained by adding methanol to latex in rollluene for 24 hours, and the results are shown in Table 1 below.

Comparative Example 1

Except that the amount of ion-exchanged water was 70 parts, 120 parts was carried out in the same manner as in Example 1, the results are shown in Table 1 below.

Example 2

80 parts of ion-exchanged water and 1.3 parts of anhydrous potassium carbonate were used as the electrolyte, and the emulsifier was carried out in the same manner as in Example 1 except that sodium rosin carbonate was selected and its amount changed to 1.8 parts and 2.2 parts. 2 is shown.

Comparative Example 2

The results were shown in Table 2 in the same manner as in Example 2 except that the amount of sodium rosin as an emulsifier was 1.0 parts, 1.4 parts, 2.6 parts, 3.0 parts, and 5.0 parts.

Example 3

Except that 80 parts of ion-exchanged water and polymerization temperature were changed from 60 degreeC to 80 degreeC, it carried out similarly to Example 1, and the result is shown in Table 3.

Comparative Example 3

The polymerization process was carried out in the same manner as in Example 3 except that the polymerization temperature was 50 ° C., and the results are shown in Table 3 below.

Example 4

The result was shown in Table 4 except that 80 parts of ion-exchanged water and t-dodecyl mercaptan used as a molecular weight modifier were changed from 0.2 parts to 0.5 parts.

[Comparative Example 4]

Except that the amount of t-dodecyl mercaptan was 0.6 parts, it was carried out in the same manner as in Example 4, the results are shown in Table 4 below.

Claims (4)

In preparing a polybutadiene latex having a number average particle diameter of 2000 kPa or more and a weight average particle diameter of 2500 kPa or more by the emulsion polymerization method, (1) water and anionic emulsifiers having a monomer / water weight ratio of 1.0-1.4 with respect to 100 parts by weight of butadiene monomer. After preparing an aqueous emulsion of butadiene containing 1.2-2.2 parts by weight of electrolyte and an amount of 0.6-0.9 parts by weight of electrolyte / emulsifier and 0.1-1.0 parts by weight of a chain transfer regulator, (2) a reaction temperature of 60- After raising to 80 ° C., 0.1-0.5 parts by weight of a free radical initiator was added to initiate polymerization, and (3) 1-3 parts by weight of anionic or nonionic emulsifier was continuously added when the conversion ratio was 50% or more, and (4) after completion of reaction. A process for producing polybutadiene tarex, comprising the step of transferring the polybutadiene latex to the unreacted monomer recovery tank and recovering the unreacted monomer. The method for producing polybutadiene latex according to claim 1, wherein the electrolyte is selected from anhydrous potassium carbonate, potassium chloride, tetrasodium pyrophosphate, sodium sulfate or the like. The method of claim 1, wherein the emulsifier is an anionic system such as sodium lauryl sulfate, sodium octyl sulfate, sodium dodecyl benzene sulfonate, sodium toluene sulfonate, potassium stearyl phosphate, potassium stearate, potassium rosinate, sodium rosinate and the like. A method for producing a polybutadiene latex comprising an emulsifier and a nonionic emulsifier such as atylene glycol stearate, polyoxyethylene nonylphenyl ester, octylphenoxypolyethyloxyethanol, or the like, alone or in combination. The method for preparing polybutadiene latex according to claim 1, wherein the molecular weight modifier is used in an amount of 0.2 to 0.5 parts by weight.