JPH05320221A - Method for producing powdery polymer - Google Patents

Abstract

(57) [Summary] [Purpose] To obtain a granular polymer with a sharp particle size distribution. [Structure] When a polymer latex containing a specific amount of a sulfate ester-based and / or sulfonic acid-based anionic surfactant is coagulated, a specific amount of the polymer in the latex is coagulated and then further coagulated.

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 a powdery polymer having a sharp particle size distribution.

[0002]

2. Description of the Related Art Heretofore, various methods have been studied for improving the powder properties of a powdery polymer obtained when recovering the powdery polymer from a polymer latex, for example, JP-A-60-217224. Japanese Patent Laid-Open Publication No. 59-91100 discloses a method of coagulating a polymer latex at a specific coagulant concentration, and Japanese Patent Laid-Open No. 59-91100 discloses a method of adding a coagulant in two or more steps. ing. However, the method of coagulation with a specific coagulant concentration is such that when no coagulation occurs due to the type and amount of the surfactant present in the latex, or when a powdery polymer having improved powder properties is used. In some cases, it may not be obtained, and there is a drawback that the applicability to a polymer latex containing a surfactant stable to a coagulant is narrow. Further, regarding the method in which the coagulant is added in two or more steps, when the latex containing only the acid-labile surfactant is coagulated, the precipitation amount and the p
Even if H is controlled, coagulation is locally completed, so that a good powdery polymer cannot be obtained.

[0003]

DISCLOSURE OF THE INVENTION As a result of intensive investigations aimed at solving the above problems, the present inventors have found that a polymer containing a specific amount of a sulfate ester-based and / or sulfonic acid-based anionic surfactant. When a latex is coagulated, a specific amount of the polymer in the latex is first coagulated, and then an acid or salt is added to complete the coagulation. The inventors have found that it is possible to provide a powdery granular polymer which can control the retaining action and the action of destructing the emulsified state of an acid, have excellent powder characteristics, and have a sharp particle size distribution.

[0004]

The present invention provides a polymer 100.
A polymer latex containing 0.05 to 0.5 parts by weight of a sulfate ester-based and / or sulfonic acid-based anionic surfactant is added to an amount of 40 parts by weight of the polymer in the latex using an acid. The present invention relates to a method for producing a powdery granular polymer, which comprises coagulating by further adding an acid or a salt after precipitation.

The present invention will be described in detail below. As the polymer latex used in the present invention, a homopolymer,
Examples thereof include copolymers and graft copolymers. As the latex of homopolymer and copolymer, dichlorostyrene, vinyl aromatic compounds such as α-methylstyrene, acrylonitrile, vinyl cyanide compounds such as methacrylonitrile,
Alkyl acrylates such as methyl acrylate, ethyl acrylate and butyl acrylate, alkyl methacrylates, and further vinyl compounds such as acrylic acid, vinyl chloride, vinylidene chloride and vinyl acetate, butadiene, chloroprene and conjugated diolefins such as isoprene and their substitution products, Examples thereof include homopolymers, copolymers or latex mixtures of these polymers made of monomers such as ethylene glycol.

The graft copolymer latex is obtained by graft-copolymerizing a monomer or a mixture of monomers capable of forming a hard polymer with an elastic trunk polymer. Examples of the elastic trunk polymer constituting the graft copolymer latex include butadiene, isoprene, chloroprene, and other diene polymers, butyl acrylate, octyl acrylate, and other alkyl group having 4 to 10 carbon atoms, and acrylate polymers.
Examples thereof include dimethyl siloxane polymers and copolymers with monomers copolymerizable therewith. As the copolymerizable monomer, styrene, aromatic vinyl such as α-methylstyrene, alkyl methacrylate such as methyl methacrylate and ethyl methacrylate, methyl acrylate,
Examples thereof include alkyl acrylates having 1 to 3 carbon atoms such as ethyl acrylate, vinyl cyanide compounds such as acrylonitrile and methacrylonitrile.

As the monomer forming the hard polymer, styrene, aromatic vinyl such as α-methylstyrene, methacrylic acid alkyl ester such as methyl methacrylate, ethyl methacrylate and butyl methacrylate, vinyl such as acrylonitrile and methacrylonitrile. Cyan compounds, vinyl halides such as vinyl chloride and vinyl bromide, etc. may be mentioned. These monomers are used alone or in combination of two or more.

In carrying out the present invention, 0.05 to 0.5 parts by weight of a sulfate ester-based and / or sulfonic acid-based anionic surfactant is present in 100 parts by weight of the polymer in the polymer latex. It is necessary to.

Among the surfactants, examples of the sulfate ester type anionic surfactant include higher alcohol sulfate ester salts and polyoxyethylene alkyl sulfate ester salts, and examples of the sulfonic acid type anionic surfactants include alkyl groups. Examples thereof include sulfonate, alkylbenzene sulfonate, alkyl sulfosuccinate, alkyl diphenyl ether sulfonate and the like. The surfactant may be added before the polymerization, during the polymerization, or at any time after the polymerization.

The above surfactant is contained in an amount of 0.05 to 0.5 parts by weight based on 100 parts by weight of the polymer. When the content of the surfactant is less than 0.05 parts by weight, the action of maintaining the emulsified state by the surfactant becomes too weak with respect to the action of destroying the emulsified state by the acid, and the precipitation state of coagulated particles is stably controlled. Is difficult to obtain, and a granular polymer having a sharp particle size distribution cannot be obtained, which is not preferable. On the other hand, if the content exceeds 0.5 parts by weight, the surfactant maintains the emulsified state too strongly, and unless a large amount of acid is used, coagulation does not occur, which is not preferable.

The emulsion polymerization method of the copolymer of the present invention may be a commonly used method, and the initiator and other polymerization aids are not particularly limited, and may be those usually used.

The acid used as the coagulant in the first step is
Examples thereof include inorganic acids such as hydrochloric acid, sulfuric acid and phosphoric acid, and organic acids such as formic acid and acetic acid.

In the present invention, as the first stage coagulation, it is necessary to coagulate 40 to 80% by weight of the polymer in the latex. The amount of polymer coagulated here was obtained by comparing the coagulated slurry with Toyo Filter Paper No. 131 (3rd of JIS P3801)
The amount of uncoagulated polymer obtained by measuring the polymer concentration in the filtrate was calculated.

If the amount of the polymer coagulated is less than 40% by weight, many polymer latexes will coagulate in the state where the emulsion state breaking action is strong when the coagulation is completed, resulting in a powdery granular polymer having a sharp particle size distribution. It is difficult to obtain, which is not preferable. On the other hand, if it exceeds 80% by weight, the effect of destroying the emulsion state is too strong, and it is difficult to obtain a powdery polymer having a sharp particle size distribution.

The acid used in the first stage is p at the time of coagulation.
It is preferable to add H to the latex so that the following conditions are satisfied.

[0016]

[Equation 2]

(Where X is the number of parts by weight of a sulfate ester-based and / or sulfonic acid-based anionic surfactant with respect to 100 parts by weight of the polymer). It is not preferable because the action of maintaining the emulsified state by the activator becomes too strong and coagulation does not occur at all, or it takes a long time to coagulate.

The coagulant used in the second stage is the first
The above-mentioned acids used in the second stage and inorganic salts such as aluminum sulfate, magnesium sulfate, sodium chloride, calcium chloride, sodium sulfate and magnesium chloride, and organic salts such as sodium acetate and calcium acetate can be used, and these are used alone. Alternatively, they are mixed and used.

When the pH of the slurry after the coagulated particles are completely precipitated is less than 2, it is preferable to adjust the pH to 2 to 4 with an alkali such as sodium hydroxide. If the obtained coagulated particles have weak shape retention and are easily broken, 50
It is preferable to heat-treat to -100 degreeC. After that, wash with water,
It is recovered as a granular polymer through a dehydration and drying process.

A typical apparatus used to carry out the present invention will be described with reference to FIG. The polymer latex is sent from the metering pump (1) and the acid is sent from the metering pump (2) to the first tank (5). The acid added to increase the recovery rate of the polymer is sent from the metering pump (3) to the second tank (6). Alkali as a pH adjusting agent for the slurry is sent from the metering pump (4) to the third tank (7). After the slurry is heat-treated in the fourth tank (8), it is further washed with water, dehydrated and dried, although not shown, to obtain a powdery polymer.

[0021]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. The examples were carried out using the apparatus shown in FIG.

Example 1 70 parts by weight of a styrene-butadiene elastic trunk polymer was polymerized with 15 parts by weight of styrene, 13.2 parts by weight of methyl methacrylate, and 1.8 parts by weight of ethyl acrylate to prepare a graft copolymer latex (solid content). Three
6%) was obtained. The average particle size of the obtained latex is 0.1.
Table 1 shows the types and amounts of the surfactants present in the latex.

The above latex and the acids of the types shown in Table 1 were
The pH and the amount of polymer (%) coagulated in the first tank were supplied so that the values shown in Table 1 were obtained. Acids of the types shown in Table 1 were supplied to the second tank so that the pH values were as shown in Table 1. Further, the alkalis of the types shown in Table 1 were supplied to the third tank so that the pH values were as shown in Table 1. The temperature of each tank was controlled to the values shown in Table 1. The slurry discharged from the fourth tank was washed with water, dehydrated and dried to obtain a granular polymer.

Various properties of the obtained powdery granular polymer were measured by the following methods. These measuring methods were commonly used in the following examples and comparative examples. The results are shown in Table 1.

Blocking resistance: The sample was filled in a powder adhesion measuring device (ED-2000CH type manufactured by Shimadzu Corporation),
After applying a constant load (0.2 Kg / cm ² ), a rupture test was performed, the maximum load at rupture was measured, and the tensile strength per unit area was obtained. Unit [g / cm ² ] Particle uniformity: The particle uniformity N is expressed by the following formula. N = D ₇₅ / D ₂₅ (wherein D ₇₅ is the particle diameter (μm) at 75% of the cumulative weight distribution curve or D ₂₅ is 25% of the cumulative weight distribution curve of the particle group.
Represents the particle size (μm). Examples 2 to 4 Example 1 except that the type of surfactant present in the latex, the pH of the first tank and the amount of polymer (%) coagulated were changed as shown in Table 1. A powdery polymer was obtained in the same manner. The evaluation results are shown in Table 1.

[0026]

[Table 1]

Example 5 The types and amounts of the surfactants present in the latex, the pH in the first tank and the amount of polymer coagulated (%), and the pH in the second tank are shown in Table 2. A powdery granular polymer was obtained in the same manner as in Example 1 except that the above was changed. The evaluation results are shown in Table 2.

[Examples 6 to 9] Except that the kind and amount of the surfactant present in the latex, the PH in the first tank and the amount (%) of the polymer coagulated were changed as shown in Table 2. Example 1
A powdery polymer was obtained in the same manner as in. The evaluation results are shown in Table 2.

[0029]

[Table 2]

Comparative Example 1 The same as Example 1 except that the pH of the first tank was changed as shown in Table 3 and the acid was not supplied to the second tank because the coagulation was completed in the first tank. To obtain a powdery polymer. The evaluation results are shown in Table 3.

[Comparative Example 2] A powdery polymer was obtained in the same manner as in Example 1 except that the pH in the first tank and the amount of polymer (%) coagulated were changed as shown in Table 3. The evaluation results are shown in Table 3.

[Comparative Example 3] A powdery polymer was obtained in the same manner as in Example 5 except that the pH in the first tank and the amount of polymer (%) coagulated were changed as shown in Table 3. The evaluation results are shown in Table 3.

[Comparative Examples 4 to 6] Examples except that the amount of the surfactant present in the latex, the pH of the first tank and the amount of polymer (%) coagulated were changed as shown in Table 3. A powdery polymer was obtained in the same manner as in 1. The evaluation results are shown in Table 3.

[0034]

[Table 3]

[Examples 10 and 11] Example 1 except that the kind of acid supplied to the first tank, the pH of the first tank and the amount of polymer (%) coagulated were changed as shown in Table 4. A powdery polymer was obtained in the same manner. The evaluation results are shown in Table 4.

[0036]

[Table 4]

Example 12 Methyl methacrylate 85
% And butyl acrylate 15% were emulsion polymerized to obtain a copolymer latex (solid content 28%). The obtained latex has an average particle size of 0.105 μm and a pH of 8.0,
The type and amount of surfactant present in the latex is shown in Table 5
As shown in.

The above-mentioned latex and the types of acids shown in Table 5 were
The pH and the amount (%) of the polymer coagulated in the first tank were supplied so that the values were as shown in Table 5. Acids of the types shown in Table 5 were supplied to the second tank so that the pH values were as shown in Table 5. In the third tank, alkali was not supplied, and only the temperature was maintained and the coagulated slurry was supplied to four tanks. The slurry discharged from the fourth tank was washed with water, dehydrated and dried to obtain a granular polymer. The evaluation results are shown in Table 5.

[Examples 13 and 14] A powdery polymer was obtained in the same manner as in Example 12 except that the pH and the amount (%) of polymer coagulated in the first tank were changed as shown in Table 5. .. The evaluation results are shown in Table 5.

[Comparative Examples 7 and 8] A powdery polymer was obtained in the same manner as in Example 12 except that the pH and the amount (%) of the polymer coagulated in the first tank were changed as shown in Table 5. .. The evaluation results are shown in Table 5.

[Comparative Example 9] Example 12 except that the amount of the surfactant present in the latex, the pH in the first tank and the amount of polymer (%) coagulated were changed as shown in Table 5. A powdery polymer was obtained in the same manner. The evaluation results are shown in Table 5.

[0042]

[Table 5]

[0043]

EFFECTS OF THE INVENTION According to the method of the present invention, by controlling the amount of precipitation of a polymer latex containing a specific amount of a surfactant at the time of coagulation, the fluidity of the powder is good and the amount of fine powder is small. Further, a powdery granular polymer having a sharp particle size distribution can be easily obtained, and the handling property of the powder can be improved.

[Brief description of drawings]

FIG. 1 is an example of a device used in the present invention.

[Explanation of symbols]

 1, 2, 3, 4 Metering pump 5 1st tank 6 2nd tank 7 3rd tank 8 4th tank

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hironari Inada 20-1 Miyuki-cho, Otake-shi, Hiroshima Mitsubishi Rayon Co., Ltd. Central Research Laboratory (72) Inventor Masaki Sugihara 20-1 Miyuki-cho, Otake-shi, Hiroshima Mitsubishi Central Research Laboratory, Rayon Co., Ltd. (72) Wataru Hatano 20-1 Miyukicho, Otake City, Hiroshima Prefecture Mitsubishi Rayon Co., Ltd. Central Research Center

Claims (2)

[Claims] 1. A sulfuric acid ester-based and / or sulfonic acid-based anionic surfactant is added in an amount of 0.05 to 100 parts by weight of the polymer.
The polymer latex containing 0.5 to 0.5 parts by weight is coagulated by adding 40 to 80% by weight of the polymer in the latex with an acid, and then adding an acid or a salt for coagulation. A method for producing a powdery polymer. 2. The method for producing a powdery polymer according to claim 1, wherein the first stage coagulation is carried out within the following pH range. [Equation 1] (In the formula, X is the number of parts by weight of the sulfate ester-based and / or sulfonic acid-based anionic surfactant with respect to 100 parts by weight of the polymer)