JPH04258618A - Production of thermoplastic resin powder - Google Patents

Abstract

PURPOSE:To obtain a fine resin powder from a graft polymer latex of a high rubber content by a simple operation. CONSTITUTION:At most 50wt.% (excluding 0wt.%) at least one member selected from the group consisting of an aromatic vinyl compound, a vinyl cyanide compound and a methacrylic ester is emulsion-polymerized in the presence of at least 50wt.% (excluding 100wt.%) rubberlike polymer latex to obtain a graft polymer latex. A water-soluble polymeric compound is added to the latex to form a dispersion of primary agglomerates, which is agglomerated by adding a water-soluble inorganic salt and/or acid thereto.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing thermoplastic resin powder, and more particularly to a method for producing thermoplastic resin powder by emulsion polymerization.

0002

[Prior Art] When coagulating and recovering graft polymer particles from a latex of a graft polymer produced by an emulsion polymerization method, an aqueous solution of a coagulant such as a water-soluble inorganic salt, an inorganic acid, or an organic acid is generally added to the latex. Or conversely, a method is used in which latex is poured into an aqueous coagulant solution, coagulated in the liquid phase to form a slurry, and then dehydrated and dried to obtain thermoplastic resin powder.

0003

[Problem to be solved by the invention] An aqueous solution of a coagulant such as a water-soluble inorganic salt or an acid is introduced into latex, or conversely, latex is introduced into an aqueous solution of a coagulant to coagulate in the liquid phase and undergo heat treatment, etc. In the method of obtaining thermoplastic resin powder by making a slurry by operation and then dehydrating and drying, it is difficult to adjust the powder particle size in the case of graft polymers with a high rubber content. particles and lumps are likely to be generated. Therefore, there are disadvantages such as troubles in the process and difficulty in removing impurities. This tendency shows that the rubber content is 50
% or more of the graft polymer latex.

[0004] In order to solve this drawback,
No. 8527 discloses a method of using a water-soluble cationic polymer compound, a water-soluble alkali metal salt, and an acid together. It is stated that this method yields finely granular coagulated polymers, and that the particles can be easily filtered and washed. In addition, this publication describes a method of using a salting-out agent such as a water-soluble inorganic salt or acid in combination with a water-soluble anionic polymer compound or a water-soluble nonionic compound as a conventional technique. It is stated that various problems in salting out polymer latex cannot be solved satisfactorily.

However, even with these methods of using a salting-out agent and a water-soluble polymer compound in combination, it is not possible to sufficiently prevent the graft polymer particles from coalescing and enlarging into lumps, and as a result, there are It is difficult to remove impurities such as incorporated emulsifiers or coagulants. This tendency is particularly remarkable in the case of graft polymer latexes with a rubber content of 50% or more.

The present invention solves the above problems and provides a method for producing thermoplastic resin powder by simple operations without using large-scale equipment.

[0007]

[Means for Solving the Problems] The present invention provides an aromatic vinyl compound, a vinyl cyanide compound, and a methacrylic acid ester in the presence of 50% by weight or more (but not including 100% by weight) of a rubbery polymer latex. Up to 50% by weight of at least one monomer selected from the group consisting of
(wt%)) and emulsion polymerization to obtain a graft polymer latex, and a process in which a water-soluble polymer compound is added to the graft polymer latex to form a primary aggregate dispersion, and a water-soluble inorganic The present invention relates to a method for producing a thermoplastic resin powder, which includes a step of solidifying by adding a salt and/or an acid.

The production method of the present invention is particularly useful for producing a rubber-modified thermoplastic resin, which is obtained by graft polymerizing a glassy polymer to a rubbery polymer to impart functionality. Rubbery polymers that can be used in the present invention include all those conventionally used as raw materials for rubber-modified thermoplastic resins, including polybutadiene, polyisoprene,
Diene rubbers such as SBR and NBR, olefin rubbers such as ethylene-propylene and ethylene-vinyl acetate, and carbon atoms of 1 or more such as polyethyl acrylate, polybutyl acrylate, polypropyl acrylate, polyhexyl acrylate, poly 2-ethylhexyl acrylate, etc. Examples include acrylic rubber having 13 alkyl groups, rubber with a core of diene rubber such as polybutadiene surrounded by acrylic rubber, and silicone rubber such as polydimethylsiloxane. In the present invention, these rubbery polymers can be used alone or in combination of two or more. These rubbery polymers are used as latex.

[0009] The monomers used in the emulsion polymerization carried out in the presence of the rubbery polymer latex are determined based on their properties as a thermoplastic resin to be obtained, their compatibility with the thermoplastic resin to be blended as necessary, At least one member selected from the group consisting of aromatic vinyl compounds such as styrene and α-methylstyrene, vinyl cyanide compounds such as acrylonitrile and methacrylonitrile, and methacrylic acid esters such as methyl methacrylate and phenyl methacrylate from the viewpoint of adhesive properties. species monomers are used. In addition, it is also possible to use other radically polymerizable monomers such as halogenated vinyl compounds such as methyl chloroacrylate and 2-chloroethyl methacrylate, and acrylic esters, if necessary.

In the present invention, the compounding ratio of the rubbery polymer latex and the monomer is 50% by weight or more (but not including 100% by weight) of the former and 50% by weight of the latter, based on the total amount of the former and the latter. (However, 0% by weight is not included). If the blending ratio deviates from this, the effects of the present invention will not be as noticeable, and troubles will occur in the isolation process due to the generation of finely granular polymers. In addition, from the viewpoint of the properties of the thermoplastic resin obtained, the former should be added in an amount of 50 to 99% by weight, especially 50 to 9% by weight.
0% by weight (i.e. 1-50% by weight of the latter, especially 10% by weight)
~50% by weight).

Emulsion polymerization of monomers in the presence of a rubbery polymer latex can be carried out by methods well known to those skilled in the art using emulsifiers, polymerization initiators, and the like.

As the emulsifier, anionic emulsifiers such as potassium oleate, sodium lauryl sulfate, and sodium dodecylbenzenesulfonate, and nonionic emulsifiers such as polyoxyethylene methyl ether can be used. They are particularly preferably used in an amount of 0.5 to 1.5% by weight, based on the total amount of rubbery polymer and monomer.

[0013] As the polymerization initiator, a redox type initiator composed of persulfate, cumene hydroperoxide, sodium formaldehyde sulfoxylate, etc. is preferably used. It is particularly preferable to use these in an amount of 0.02 to 5.0% by weight based on the total amount of monomers.

A graft polymer latex is obtained as described above, and it is preferable that the solid content concentration of the obtained graft polymer latex is adjusted to be 30% by weight or less. When the solid content concentration exceeds 30% by weight, oversized particles are likely to be generated. Adjustment can be carried out by conventional methods such as adding water and stirring.

The obtained graft polymer latex is then demulsified and coagulated as graft polymer particles. In the present invention, first, a water-soluble polymer compound is added to the graft polymer latex to prepare a primary aggregate dispersion.

Water-soluble polymer compounds that can be used include polyvinyl alcohol, hydroxyethyl cellulose, gelatin, hydroxyethyl methacrylate, sodium polyacrylate, polyethylene oxide, polyethyleneimine, chitosan, polyvinylpyrrolidone, polydimethylaminoethyl methacrylate, polyacrylamide, Examples include dimethylaminoethyl methacrylate-acrylamide copolymer, among others, water-soluble nonionic polymers are preferred from the viewpoint of uniformity of the particle size of the obtained coagulated polymer, prevention of generation of excessive particles, isolation of coagulated polymer, and washing. High molecular compounds are preferred, and polyvinyl alcohol is particularly preferred from the viewpoint of effectiveness and economy.

[0017] Such a water-soluble polymer compound is used in an amount of 0.1 to 5 parts by weight per 100 parts by weight of the graft polymer in the latex, although it varies depending on the type of latex of the graft polymer, the temperature at the time of coagulation, etc. It is preferably added in an amount of 0.3 to 3 parts by weight, particularly preferably 0.3 to 3 parts by weight. If less than 0.1 parts by weight is added, the ability to effectively demulsify the latex of the graft polymer is poor, and a thermoplastic resin powder cannot be obtained. Contrary to this, even when adding more than 5 parts by weight of a water-soluble polymer compound, no increase in the effect was observed as the amount added increased; may remain in the resin, leading to a decrease in the properties of the resin. It is also economically disadvantageous,
Undesirable.

In the present invention, after obtaining a primary aggregate dispersion by adding a water-soluble polymer compound, a water-soluble inorganic salt and/or acid is subsequently added. In other words, it is important to add a water-soluble inorganic salt and/or acid after the phase is changed from an emulsified state to a suspended state by the action of a water-soluble polymer compound. Not only the simultaneous addition of salts and/or acids, but also the effects of the present invention cannot be achieved sufficiently if the water-soluble inorganic salts and/or acids are added too early. For example, after adding a water-soluble polymer compound,
If a water-soluble inorganic salt and/or acid is added before the system completely changes from an emulsified state to a suspended system, oversized particles will be produced and the above-mentioned problems will not be solved.

In addition, in the present invention, it is important to add a water-soluble inorganic salt and/or an acid, and it is possible to break the emulsification and obtain agglomerated polymer particles simply by adding a water-soluble polymer compound. In this case, the resulting particles have a low bulk density, and also have the disadvantage that they are easily colored during heating and drying, probably due to the influence of residual impurities.

As water-soluble inorganic salts, alkali metal salts or alkaline earth metal salts of inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, thiosulfuric acid, and boric acid, or double salts such as potassium alum and ammonium alum can be used. Among these, potassium alum is particularly preferred. In addition, as the acid, inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, thiosulfuric acid, and boric acid, and organic acids such as acetic acid, citric acid, ascorbic acid, malic acid, and maleic acid can be used.

When such water-soluble inorganic salts and/or acids are used, they are preferably added in an amount of 0 to 20 parts by weight based on 100 parts by weight of the graft polymer in the latex. Even if it is used in an amount exceeding 20 parts by weight, no increase in effectiveness is observed as the amount added increases.

The amount of the water-soluble polymer compound to be used is preferably selected within the above-mentioned range; however, the larger the amount used, the easier it will be to coagulate at a lower temperature. Furthermore, when coagulating at a constant temperature, the larger the amount of the water-soluble polymer compound used, the easier it is to obtain particles with a finer particle size. When coagulating the graft polymer latex according to the present invention, a water-soluble polymer compound, a water-soluble inorganic salt and/or
Alternatively, there are no particular restrictions on the method of adding the acid, other than the timing of addition as described above, but in order to uniformly and quickly mix the polymer compound with the graft polymer latex, it is preferable to form it into an aqueous solution in advance. Further, the temperature during solidification can be varied over a wide range of 0 to 100°C, but it is particularly preferable to perform the solidification at 50°C or lower because the effects of the present invention can be easily exhibited.

[0023] By coagulating the graft polymer latex as described above, a thermoplastic resin powder with fine particles can be obtained. The resulting coagulated particles can be filtered and washed by conventional methods. In the present invention, the filtration and washing steps are particularly easy, and catalyst residues, emulsifiers, coagulants, etc. can be removed by using a relatively small amount of washing water, and the workability is excellent.

The thermoplastic resin powder obtained by the present invention can be blended with other resins if necessary and used for various molded products.

[0025]

EXAMPLES Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited to these Examples. Hereinafter, "part" in the examples means parts by weight, and "%" means % by weight.

Example 1 (1) Production of graft polymer 10 parts of potassium oleate and 24 parts of deionized water were placed in a reactor.
Add 300 parts of polybutadiene latex (Nippon Zeon Co., Ltd., UB-1001S) and dissolve it uniformly.
After mixing and stirring, 14 parts of triallylisocyanurate dissolved in 700 parts of butyl acrylate were added, and the mixture was purged with nitrogen. Thereafter, an aqueous solution of 0.4 part of potassium persulfate dissolved in 100 parts of deionized water and an aqueous solution of 0.04 part of sodium sulfite dissolved in 100 parts of deionized water were added, and the temperature was raised. Approximately 4 at 60-65℃
After polymerization for a period of time, the polymerization was stopped by cooling to obtain a rubbery polymer latex. Next, the following two types of ingredients are prepared. Ingredients ■ Sodium lauryl sulfate
1.2 parts potassium oleate
8.7 parts deionized water
240 parts Ingredients ■ Cumene hydroperoxide 0.7 parts Tertiary decyl mercaptan 0.6 parts Styrene
1
38 parts acrylonitrile
Into a 62-part reactor, 800 parts (as solid content) of the rubbery polymer latex obtained by the above method and uniformly dissolved components (1) and (2) were charged, and while stirring, the mixture was replaced with nitrogen and the temperature was raised. . Polymerize at 65°C for about 6 hours,
After confirming that the polymerization rate was 90% or more, polymerization was carried out at 80° C. for 2 hours to obtain a graft polymer latex (A) with a polymerization rate of 96% or more.

(2) 1700 parts of the above graft polymer latex (solid content: 5
00 parts) and 850 parts of deionized water were mixed and stirred at 23°C. Next, 350 parts of a 2% aqueous polyvinyl alcohol solution prepared with deionized water was added to coagulate the graft polymer particles to form a primary aggregate dispersion, and then 10 parts of potassium alum was dissolved in 100 parts of deionized water. The prepared aqueous solution was added, dehydrated, washed, and dried to obtain a thermoplastic resin powder.

(3) Evaluation The powder produced in (2) above was tested using PIP-400 manufactured by ADS.
The average particle size was measured using a particle size distribution measurement package. The thermoplastic resin powder obtained in Example 1 had an average particle size of 0.
20 fine granular powder.

Examples 2 to 5 Using the graft polymer latex obtained in Example 1, graft polymerization was carried out at 23° C. in the same manner as in Example 1, with the amount of latex, amount of deionized water, and amount of coagulant shown in Table 1. Coagulation of the combined particles was performed. The average particle size of the obtained thermoplastic resin powder was measured and evaluated by the method shown in Example 1. The results are shown in Table 1.

Comparative Example 1 1700 parts of the graft polymer latex produced in Example 1 (solid content 500 parts) and 130 parts of deionized water were placed in a reactor.
Add 0 parts and mix and stir at 23°C. Next, an aqueous solution prepared by dissolving 10 parts of potassium alum in 100 parts of deionized water was added to solidify the graft polymer particles, followed by dehydration, washing, and drying to obtain a thermoplastic resin powder. The average particle diameter of this powder was measured and evaluated by the method shown in Example 1. The thermoplastic resin obtained in Comparative Example 1 had irregular particle sizes, and the average particle size was as large as 5 mm. The results are shown in Table 1.

Comparative Example 2 In a reactor, 50 parts of potassium alum and 1300 parts of deionized water were added.
Mix and stir. Once the potassium alum is dissolved, the graft polymer latex 17 obtained in Example 1
00 parts (solid content: 500 parts) was added at a rate of 50 parts per minute to coagulate the graft polymer particles, followed by dehydration, washing, and drying to obtain a thermoplastic resin powder. The obtained thermoplastic resin did not become spherical, but was agglomerated and enlarged, and the size was the size of an azuki bean. This is because the average particle size of the powder could not be measured using the method shown in Example 1. The results are shown in Table 1.

[0032]

[Table 1]

Examples 6 to 11 The graft polymer latex obtained in Example 1 was used in the same manner as in Example 1, with the formulations shown in Table 2, including the amount of latex, the amount of deionized water, the amount of coagulant, and the coagulation temperature. Coagulation of the polymer particles was performed. The average particle size of the obtained thermoplastic resin powder was measured and evaluated by the method shown in Example 1. The results are shown in Table 2.

[0034]

[Table 2]

Example 12 The rubbery polymer latex 700 obtained in Example 1 was placed in a reactor.
(as solid content) and the following components (1) and (2) uniformly dissolved were added, and while stirring and mixing, the mixture was purged with nitrogen and the temperature was raised. Polymerization was carried out at 65° C. for about 6 hours, and after confirming that the polymerization rate was 90% or more, polymerization was carried out at 80° C. for 2 hours to obtain a graft polymer latex (B) with a polymerization rate of 96% or more. Ingredients ■ Sodium lauryl sulfate
1.8 parts potassium oleate
13.1 part deionized water
240 parts Ingredients ■ Cumene hydroperoxide 1.1 parts Tertiary decyl mercaptan 1.0 parts Styrene
20
7 parts acrylonitrile
93 parts of the obtained graft polymer latex was coagulated into graft polymer particles in the same manner as in Example 1, using the formulations shown in Table 3 for the amount of latex, amount of deionized water, and amount of coagulant. The average particle size of the obtained thermoplastic resin powder was measured and evaluated by the method shown in Example 1. The results are shown in Table 3.

Example 13 Rubbery polymer latex 500 obtained in Example 1 was placed in a reactor.
(as solid content) and the following components (1) and (2) uniformly dissolved were added, and while stirring and mixing, the mixture was purged with nitrogen and the temperature was raised. Polymerization was carried out at 65°C for about 6 hours, and after confirming that the polymerization rate was 90% or more, polymerization was carried out at 80°C for 2 hours to obtain a graft polymer latex (C) with a polymerization rate of 96% or more. Ingredients ■ Sodium lauryl sulfate
3.0 parts potassium oleate
21.7 parts deionized water
600 parts Ingredients ■ Cumene hydroperoxide 1.8 parts Tertiary decyl mercaptan 1.6 parts Styrene
345 parts acrylonitrile
155 parts of the obtained graft polymer latex was coagulated into graft polymer particles in the same manner as in Example 1, using the formulations shown in Table 3 for the amount of latex, amount of deionized water, and amount of coagulant. The average particle size of the obtained thermoplastic resin powder was measured and evaluated by the method shown in Example 1. The results are shown in Table 3.

Comparative Example 3 The rubbery polymer latex 400 obtained in Example 1 was placed in a reactor.
The following components (1) and (2) uniformly dissolved were added, and while stirring and purging with nitrogen, the temperature was raised. Polymerization was carried out at 65° C. for about 6 hours, and after confirming that the polymerization rate was 90% or more, polymerization was carried out at 80° C. for 2 hours to obtain a graft polymer latex (D) with a polymerization rate of 96% or more. Ingredients ■ Sodium lauryl sulfate
3.6 parts potassium oleate
26.0 parts deionized water
720 parts Ingredients ■ Cumene hydroperoxide 2.2 parts Tertiary decyl mercaptan 1.9 parts Styrene
414 parts acrylonitrile
Using 186 parts of the obtained graft polymer latex, graft polymer particles were coagulated in the same manner as in Example 1, using the formulations shown in Table 3 for the amount of latex, amount of deionized water, and amount of coagulant. Problems occurred during the isolation process due to the generation of very fine particles. The average particle size of the obtained thermoplastic resin powder was measured and evaluated by the method shown in Example 1. The results are shown in Table 3.

[0038]

[Table 3]

Example 14 The graft polymer latex obtained in Example 1 was treated in the same manner as in Example 1, using polyacrylic sodium as the water-soluble polymer, and the amount of latex, deionized water, and coagulant were adjusted. The graft polymer particles were coagulated using the formulation shown in Table 4. The average particle size of the obtained thermoplastic resin powder was measured and evaluated by the method shown in Example 1. The results are shown in Table 4.

Examples 15 to 17 The graft polymer latex obtained in Example 1 was prepared in the same manner as in Example 1, with the amount of latex, amount of deionized water, type and amount of coagulant shown in Table 4. Coagulation of the graft polymer particles was performed. The average particle size of the obtained thermoplastic resin powder was measured and evaluated by the method shown in Example 1. The results are shown in Table 4. In Examples 15 to 18, the particle size distribution was somewhat broader than in Example 1, and post-treatment was also somewhat difficult.

[0041]

[Table 4]

Comparative Example 4 1700 parts of the graft polymer latex obtained in Example 1 (solid content 500 parts) and 800 parts of deionized water were placed in a reactor.
Mix and stir at 23°C. Next, 500 parts of a 2% polyvinyl alcohol aqueous solution prepared with deionized water was added to coagulate the graft polymer particles, followed by dehydration, washing, and drying to obtain a thermoplastic resin powder. When the average particle size of the obtained resin powder was measured by the method shown in Example 1,
Although it was 0.36 mm and fine granular, it was colored yellow when dried.

Comparative Example 5 1700 parts of the graft polymer latex obtained in Example 1 (solid content: 500 parts) and 850 parts of deionized water were charged into a reactor and mixed and stirred at 23°C. Next, a 2% polyvinyl alcohol aqueous solution prepared with deionized water is added, and after about 5 minutes, before the phase inversion from emulsion to suspension has occurred, 10 parts of potassium alum is added to 100 parts of deionized water. was added to coagulate the graft polymer particles. After dehydration, washing, and drying, the average particle size of the obtained thermoplastic resin was measured by the method shown in Example 1, and was found to be 3.5 m.
It was large, m.

[0044]

[Effects of the Invention] According to the method of the present invention, fine-particle thermoplastic resin powder can be produced from graft polymer latex with simple operations without using large-scale equipment as conventionally used. can. Furthermore, in the method of the present invention, the coagulated particles are easy to filter and wash, and polymerization catalyst residues, emulsifiers, and coagulants can be effectively washed just by using a small amount of washing water.

Claims (4)

[Claims] Claim 1: In the presence of 50% by weight or more (but not including 100% by weight) of a rubbery polymer latex, at least one compound selected from the group consisting of an aromatic vinyl compound, a vinyl cyanide compound, and a methacrylic acid ester. A process of blending 50% by weight or less (excluding 0% by weight) of one type of monomer and emulsion polymerizing to obtain a graft polymer latex, and adding a water-soluble polymer compound to the graft polymer latex. 1. A method for producing a thermoplastic resin powder, comprising the step of preparing a primary aggregate dispersion and then coagulating it by adding a water-soluble inorganic salt and/or an acid. 2. The method for producing a thermoplastic resin powder according to claim 1, wherein the solid content concentration in the graft polymer latex is 30% or less. 3. The method for producing thermoplastic resin powder according to claim 1 or 2, wherein the water-soluble polymer compound is a water-soluble nonionic polymer compound. 4. The method for producing thermoplastic resin powder according to claim 3, wherein the water-soluble nonionic polymer compound is polyvinyl alcohol.