JPH0225361B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for preventing polymer scale from adhering to the vessel walls, stirrer, etc. in a salting-out tank with which a butadiene-based polymer latex comes into contact when salting out. The above-mentioned polymer scale is formed when the latex becomes unstable and polymer particles adhere to the precipitator wall, stirrer, etc., or when the latex adhering area dries as it is, especially near the liquid surface of the latex. It is mostly formed on the vessel wall surface at the gas-liquid interface. Such polymer scale peels off from the attached part and mixes into the product, resulting in a disadvantage of lowering the quality of the product, and on the other hand, it only requires excessive labor and time to remove the attached scale. Moreover, since unreacted monomers are adsorbed in this polymer scale, there is a disadvantage that there is a risk of injury to the human body due to the monomers, which has become a very serious problem in recent years. The present invention was completed as a result of intensive research to solve the problem of polymer scale formation caused by butadiene polymer latex. It is characterized by applying a mixture of acid dye and basic dye or oil-soluble dye to 1 part silicic acid compound in a weight ratio of 0.01 to 10 on the vessel wall, stirrer, etc. in advance and drying it. The present invention relates to a method for preventing polymer scale adhesion. The present invention also provides a scale adhesion inhibitor for polymer latex (used to prevent scale adhesion formed by contact of polymer latex), which is made of a mixture of a dye and a silicate compound as a main ingredient. be. According to the present invention, the adhesion of scale based on butadiene polymer latex on the walls of the salting-out tank, the stirrer, etc. is significantly prevented, and this effect is due to the fact that the equipment is made of stainless steel, carbon steel, or glass lined. Regardless of whether it is manufactured by
It also has the advantage that it can be achieved without being affected by the type of butadiene polymer latex. The mechanism by which the adhesion of polymer scale is prevented by the present invention is probably due to the coating of the mixture of the mixed dye and silicic acid compound described above, which forms a coating film that is sufficiently adsorbed to the vessel wall, etc., and this coating film becomes latex. It is presumed that this is because it acts to prevent specific adsorption of any dissociated molecules or undissociated molecules present therein. Next, the content of the present invention will be explained in detail. The mixed dye used in the present invention is a mixture of an acidic dye and a basic dye or an oil-soluble dye, and specific examples of these dyes are as follows. Acidic dye CI acid yellow 7, 17, 23, 25, 40, 44,
72, 75, 98, 99, 114, 131, 141, CI acid orange 19, 45, 74, 85, 95, CI acid red 6, 32, 42, 52, 57, 75, 80, 94, 111, 114,
115, 118, 119, 130, 131, 133, 134, 145, 168,
180, 184, 194, 198, 217, 249, 303, CI Assisted Violet 34, 47, 48, CI Assisted Blue 15, 29, 43, 45, 54, 59, 80, 100, 102, 113,
120, 130, 140, 151, 154, 184, 187, 229, CI
Acid green 7, 12, 16, 20, 44, 57, CI
Acid Brown 39, 301, CI Acid Black 1, 2, 24, 26, 29, 31, 48, 52, 63, 131,
140, 155 etc. Basic dye CI Basic Yellow 11, 14, 19, 21, 28,
33, 34, 35, 36, CI Basic Orange 2,
14, 15, 21, 32, CI Basic Cred 13, 14,
18, 22, 23, 24, 29, 32, 35, 36, 37, 38, 39,
40, CI basic violet 7, 10, 15,
21, 25, 26, 27, CI basic blue 9, 24,
54, 58, 60, CI Basic Black 8, etc. Oil-soluble dye CI Solvent Yellow 2, 6, 14, 19, 21,
33, 61, CI Solvent Orange 1, 5, 6,
14, 37, 44, 45, CI Solvent Red 1, 3,
8, 23, 24, 25, 27, 30, 49, 81, 82, 83, 84,
100, 109, 121, CI Solvent Violet 1,
8, 13, 14, 21, 27, CI Solvent Blue 2,
11, 12, 25, 35, 36, 55, 73, CI Solvent Green 1, 3, CI Solvent Brown 3, 5,
20, 37, CI Solvent Black 3, 5, 7,
22, 23, 123, etc. In the present invention, a mixture of the above-mentioned dyes and a silicic acid compound are dissolved in a suitable solvent at a concentration of approximately 0.01 to 5% by weight to form a treatment liquid, and this treatment liquid (coating liquid) is applied to the vessel walls and pipes that the polymer latex comes into contact with. It is applied to walls and other contact areas and then dried at temperatures ranging from room temperature to about 100°C, or the area to be applied is heated in advance and applied to the heated surface. Examples of solvents for dissolving dyes include alcohol solvents, aliphatic hydrocarbon solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, ketone solvents, ester solvents, ether solvents, and water. For example, these solvents may be used alone or as a mixed solvent of two or more. The silicic acid compounds used with the above dyes include:
Colloidal silica, water-soluble silicic acids, or silicate compounds are included, and specific examples thereof are as follows. Colloidal silica, orthosilicic acid, metasilicic acid, mesodisilicic acid, mesotrisilicate, mesotetrasilicic acid, sodium metasilicate, potassium hydrogen disilicate,
Lithium orthosilicate, hexalithium orthodisilicate, water glass, 12-tungstosilicic acid, iso-
12-silicotungstic acid, 10-silicotungstic acid, 12-potassium silicotungstate, iso-12
- Potassium silicotungstate, 10-potassium silicotungstate, 12-sodium silicotungstate, iso-12-sodium silicotungstate, silicomolybdic acid, potassium silicomolybdate, sodium silicomolybdate, etc. These silicic acid compounds may be dissolved or dispersed in a small amount of water and mixed into the dye coating solution, and the mixing ratio of the silicic acid compounds in this case is 0.01 to 10 parts by weight to 1 part dye. Needed. The concentration of the coating liquid is generally desirably about 0.01 to 5%, particularly about 0.05 to 1%, taking into account coating workability and the like. The amount of application is the amount of application after drying.
The content may be set to 0.001 g/m ² or more. As a means of coating and drying, after coating, suitably heated air is blown onto the coated surface to dry it, or the inner wall of the salting-out tank and other parts that come into contact with the latex are preheated (40 to 100°C). Any method such as applying directly to the heated surface and drying may be used, but the coated surface may be thoroughly dried and then washed with water if necessary. In this manner, the inner wall and other areas in contact with the latex are coated with a coating solution of the above mixed dye and silicic acid compound, and then the butadiene polymer latex is charged and operations such as salting out are carried out. Further, salting out is carried out in a salting out tank equipped with a stirrer. Salting-out agents such as chlorides such as sodium chloride, calcium chloride, and magnesium chloride, sulfates such as sodium sulfate, magnesium sulfate, and aluminum sulfate, sulfuric acid, and some other nitrates or metal salts of organic acids are usually added to the latex. Water is added so that the solid content is 1.0 to 10.0% by weight based on the dry weight of the polymer, and the polymer concentration in the salting out slurry reel is 5 to 30%, and the process is carried out at a temperature of 70 to 100°C. be exposed. The method of the present invention is applied to removing residual monomers or salting out various latexes, and specific examples of this polymerized latex include styrene-butadiene rubber latex, carboxyl-modified styrene-butadiene-rubber latex, and butadiene rubber latex. Examples include rubber latex, acrylonitrile-butadiene rubber latex, chlorobrene latex, methacrylate-butadiene latex, butadiene-styrene-vinylpyridine latex, and ABS emulsion graft polymerization latex. Next, a specific example will be given. However, in the following description, only parts or parts by weight are shown. Example 1 60 parts of polybutadiene latex (solid content 60%)
, 0.4 parts of potassium persulfate, 3 parts of sodium laurate,
ABS made by mixing 0.1 part of sodium bicarbonate and 160 parts of water, adding 45 parts of styrene, 19 parts of acrylonitrile, and 0.2 parts of n-dodecyl mercaptan and polymerizing at 60°C.
The graft polymer latex was salted out as follows. First, a dye coating solution or a coating solution of a dye and a silicate compound is applied to the inner wall of a stainless steel salting-out tank with an internal volume of 100 and equipped with a stirrer and other parts that come in contact with the latex, and the coated surface is heated to 60°C. 15
After drying for a minute, it was washed with water. As the coating liquid, the first
A 0.1% by weight methanol solution of the dye or a mixture of dye and silicic acid compound shown in the table was used. Mix 1 part of a 15% aqueous solution of magnesium sulfate, which was adjusted to 5% with respect to the dry standard polymer in the latex during salting out, and 15 parts of water in the salting-out tank coated in this way. While heating and stirring at 95°C±2°C, 8 parts of the above latex was added dropwise over 10 minutes for salting out treatment. After removing the salted out product, the amount of scale adhesion was examined, and the results shown in Table 1 were obtained. Regarding the dyes in the table, CI Direct Orange 39 and CI Direct Blue 71 are direct dyes, and CI Fluorescent Brightening Agent 91 is a fluorescent whitening agent.

【table】

[Table] Example 2 75 parts of 1,3-butadiene monomer, 25 parts of styrene
180 parts of water, 4.5 parts of sodium dodecylbenzenesulfonate, 0.6 parts of stearic acid, 0.5 parts of t-dodecyl mercaptan, 0.3 parts of potassium chloride, 0.1 parts of sodium pyrophosphate, 0.1 parts of ferrous sulfate, and 0.35 parts of hydrogen peroxide. The styrene-butidiene rubber latex, which was added and weighed at 30°C, was salted out as follows. First, a 0.5% by weight solution of a mixture of a dye and a silicate compound (with water as a solvent and A mixture of methyl alcohol (80/20 weight ratio) was applied, dried at 50°C for 30 minutes, and then washed with water. Into the salting-out tank coated in this way, 15 parts of a salting-out agent aqueous solution adjusted so that the amount of calcium chloride was 7% by weight based on the dry weight of the polymer in the latex was heated and stirred at 90°C. While doing so, 12 parts of styrene-butadiene rubber latex was added dropwise over 20 minutes for salting out treatment. This operation is considered to be one batch, and after removing the salted-out material, the same salting-out is performed continuously, and the number of times salting-out can be performed without the amount of scale adhesion exceeding 1 g/m ² (number of scale prevention times) is determined. As a result, the results shown in Table 2 were obtained. In addition, among the dyes in the table, CI Direct Violet 90 and CI Direct Brown 170
is a direct dye.

【table】

【table】

Claims (1)

[Scope of Claims] 1. When salting out a butadiene-based polymer latex, the vessel walls, stirrer, etc. in the salting-out tank with which the butadiene-based polymer latex comes into contact are preliminarily coated with an acidic dye and a basic silicic acid compound in a weight ratio of 1 to 1. A method for preventing polymer scale adhesion, which comprises applying and drying a mixture of a dye or a mixed dye with an oil-soluble dye at a ratio of 0.01 to 10. 2 A mixture of the silicic acid compound and a mixed dye of an acidic dye and a basic dye or an oil-soluble dye is applied at a concentration of 0.01 to 5% by weight and an amount of 0.001 g/m ² or more after drying. A method for preventing polymer scale adhesion according to claim 1.