JP2522731B2 - Method for preventing adhesion of polymer scale and polymer scale inhibitor used therefor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing adhesion of polymer scale in the polymerization of a monomer having an ethylenic double bond, and a polymer scale inhibitor used in the method.

[0002]

2. Description of the Related Art In a method for producing a polymer by polymerizing monomers in a polymerization vessel, it is known that the polymer adheres to the inner wall surface of the polymerization vessel as a scale. If the polymer scale adheres to the inner wall surface of the polymerization vessel, the yield of the polymer,
The cooling capacity of the polymerization vessel is deteriorated, the adhered polymer scale peels off and is mixed into the product, which leads to the deterioration of the quality of the product polymer.In addition, a great deal of labor and time are required to remove the polymer scale. The disadvantage of. In addition, since the polymer scale contains unreacted monomers, workers may be exposed to this and cause physical disability.

Heretofore, as a method for preventing the adhesion of polymer scale to the inner wall surface of a polymerization vessel in suspension polymerization or emulsion polymerization of a monomer having an ethylenic double bond, the following substances are exemplified by a scale inhibitor. Has been proposed. For example, a specific polar organic compound (Japanese Patent Publication Sho 45
-30343), dyes and pigments (JP-B-45-30835), aromatic amine compounds (JP-A-51-50887), reaction products of phenolic compounds with aromatic aldehydes (JP-A-55).
-54317). These methods can effectively prevent the adhesion of polymer scale in the polymerization of a vinyl halide monomer such as vinyl chloride or a monomer mixture mainly containing the monomer.

[0004]

The polymer scale anti-adhesive used in the above-mentioned conventional method is disclosed in Japanese Patent Publication No.
No. 30835 and Japanese Patent Publication No. 52-24953, dyes or pigments, aromatic amine compounds described in JP-A-51-50887 and phenolic compounds described in JP-A-55-54317 and aromatic aldehydes As represented by reaction products and the like, there are generally many colored products. As described above, these polymer scale adhesion preventive agents can effectively adhere to the polymer scale in the polymerization of a vinyl halide monomer such as vinyl chloride or a monomer mixture mainly containing the monomer. Although it can be prevented, if the coating of such a colored polymer scale anti-adhesion agent dissolves, thereby contaminating the product polymer, the product polymer is colored and the quality is significantly reduced. The problem that it ends up arises. Further, among the polar compounds described in JP-B-45-30343, deleterious substances such as alinine, nitrobenzene and formaldehyde, and among the pigments described in JP-B-45-30835, heavy metals such as chromium and lead are contained. Containing toxic substances, and also Japanese Patent Publication Nos. 45-30835 and 52-52
Some of the dyes described in 24953 may be carcinogenic. Therefore, when these compounds are used, a safety problem for workers occurs.

[0005]

Therefore, an object of the present invention is to provide a method for preventing adhesion of polymer scale, which can effectively prevent the adhesion of polymer scale and does not contaminate the product polymer. An object is to provide a polymer scale anti-adhesion agent used in this method. As a result of intensive studies, the inventors of the present invention have found that the above problems can be solved by forming a coating film made of a water-soluble basic polysaccharide on the inner wall surface of a polymerization vessel. That is, the present invention, as a solution to the above problems, in the polymerization of the monomer having an ethylenic double bond in the polymerization vessel, a method for preventing the adhesion of polymer scale, the inner wall surface of the polymerization vessel The present invention provides a method for preventing adhesion of polymer scale, which comprises performing the above-mentioned polymerization in a polymerization vessel in which a coating film of a water-soluble basic polysaccharide has been formed in advance. The present invention also provides a polymer scale inhibitor containing a water-soluble basic polysaccharide, which is used in the above method.

Water-soluble basic polysaccharides The water-soluble basic polysaccharides used in the method of the present invention include:
Examples include chitosan, water-soluble chitosan derivative, polygalactosamine, water-soluble polygalactosamine derivative, and water-soluble chitin.

Chitosan is a polysaccharide (poly-1,4-polysaccharide in which D-glucosamine is linearly linked by β-1,4 bond).
β-glucosamine), which is obtained by deacetylating chitin contained in the shells of crustaceans such as shrimp and crab. Recently, it is produced by culturing filamentous fungi and can be used like natural products. Chitosan is water-insoluble under neutral conditions but soluble in acidic aqueous solutions, so it is used under conditions of pH <7.

The following are examples of water-soluble chitosan derivatives used in the method of the present invention. (1) Chitosan salts of organic or inorganic acids. Specific examples thereof include acetic acid, glycolic acid, malic acid, citric acid, ascorbic acid and the like, and examples of the inorganic acid include hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid and the like. The deacetylation degree of chitosan is preferably 40 to 100%. (2) A water-soluble low molecular weight product obtained by decomposing chitosan, that is, a water-soluble glucosamine oligomer. Such a water-soluble glucosamine oligomer is preferably a 5- to 20-mer, and can be obtained by a usual molecular weight reduction method, such as a hydrochloric acid hydrolysis method (JP-A-61-21102), a nitrite decomposition method (JP-A-61-21102). 62-184002), chlorine decomposition method (JP-A-60-186504)
No.), a phosphoric acid decomposition method, an enzymatic or microbial decomposition method, or the like. (3) A water-soluble derivative by introducing a hydrophilic group into chitosan.
Specific examples of these include polyoxyethylene chitosan, polyoxypropylene chitosan, phosphorylated chitosan, N-glycidyltrimethylammonium chitosan, dihydropropyl chitosan and the like, which are listed in KAISHO 63-14714.

The polygalactosamine used in the method of the present invention is also insoluble in water under neutral conditions, but soluble under conditions where the pH is less than 7, and can be used. Polygalactosamine can be produced using the culture of filamentous fungi (1990.
2.20 Published by Gihodo Shuppan Co., Ltd., edited by Chitin Chitosan Study Group, “Applications of Chitin and Chitosan”, pp. 24-26).

Examples of the polygalactosamine derivative include the following. (1) An organic or inorganic acid salt of polygalactosamine. Specific examples thereof include salts of organic acids such as acetic acid and formic acid, and salts of inorganic acids such as hydrochloric acid and nitric acid. (2) A water-soluble low molecular weight product obtained by decomposing polygalactosamine, that is, a galactosamine oligomer. Such a water-soluble galactosamine oligomer is preferably a 5- to 20-mer, and can be obtained by, for example, an enzyme or microbial decomposition method.

Examples of the water-soluble chitin derivative used in the method of the present invention include the following. (1) Water-soluble N-obtained by degrading chitin to lower molecular weight
Acetylglucosamine oligomer. Such an oligomer is preferably a 5- to 20-mer, and can be obtained by a conventional method for depolymerizing, for example, a nitrite decomposition method, a formic acid decomposition method, a chlorine decomposition method (JP-A-60-186504), and an enzyme ( For example, chitinase) or a microbial decomposition method. (2) A derivative which is made water-soluble by introducing a hydrophilic group into chitin. Specific examples of these include polyoxyethylene chitin, polyoxypropylene chitin, phosphorylated chitin and dihydropropyl chitin, which are described in JP-A-63-14714.

Among the water-soluble basic polysaccharides described above, the most preferable one is 20% when an aqueous solution having a deacetylation degree of 65% or more, a chitosan concentration of 0.5% by weight and an acetic acid concentration of 0.5% by weight is measured by a B type viscometer. Organic and inorganic acid salts of chitosan with a viscosity of 30 cP or more at ℃, and a molecular weight of 10,000
These are organic acid salts and inorganic acid salts of polygalactosamine.

Preferred Embodiment In a preferred embodiment of the present invention, tannins are used in combination with the water-soluble basic polysaccharide, whereby the polymer scale prevention effect is further improved. The tannins used include, for example, tannic acid, quintuple tannin, gallic tannin, smack tannin, tara tannin, baronia tannin, chestnut tannin, myrobalan tannin, oak tannin, dividivitannin, and argalovia tannin. Degradable tannins: condensed tannins such as Gambian tannin, quebracho tannin, mimosa tannin, mangrove tannin, hemlock tannin, sprue tannin, burmacattanin nin, oak bark tannin, oyster astringent tannin and the like. These may be used alone or in combination of two or more.
Among these, tannic acid, quintuple tannin, gallic tannin, kebracho tannin, mimosa tannin, oak bark tannin, and oyster astringent tannin are preferable. This tannin is usually 0.1% by weight per 100 parts by weight of the basic polysaccharide.
~ 1000 parts by weight, preferably 1 to 600 parts by weight.
If the amount of tannins used is too large or too small, the improvement of the polymer scale prevention effect by the combined use will be small.

Preparation of coating liquid To form a coating film by applying the polymer scale inhibitor used in the present invention to the inner wall surface of a polymerization vessel, etc., usually, it is dissolved in an appropriate solvent to form a solution (hereinafter referred to as a solution). , A coating solution), which is then applied to the inner wall surface and dried. The concentration of the water-soluble basic polysaccharide in the coating liquid, the total concentration of the water-soluble basic polysaccharide and tannins when tannins are used in combination is not particularly limited as long as the total coating amount described below can be obtained, Usually, 0.001 to 15% by weight is sufficient. Examples of the solvent used for preparing the coating liquid include water; methanol, ethanol, propanol, butanol, 2-
Butanol, 2-methyl-1-propanol, 2-methyl-2-propanol, 3-methyl-1-butanol, 2
-Methyl-2-butanol, 2-pentanol, and other alcoholic solvents; Acetone, methyl ethyl ketone, methyl isobutyl ketone, and other ketone solvents; Methyl formate, ethyl formate, methyl acetate, methyl acetoacetate, and other ester solvents; 4- Ether-based solvents such as methyldioxolane and ethylene glycol diethyl ether; furans; aprotic solvents such as dimethylformamide, dimethylsulfoxide, acetonitrile and the like can be used. These are appropriately used alone or as a mixed solvent of two or more kinds.

Further, to the scale preventive agent of the present invention, for example, a surfactant (chaotic, nonionic and anionic) and the like can be added as long as the scale preventing effect is not impaired. Further, an inorganic compound may be appropriately added if necessary, as long as the colorlessness and nontoxicity which are the objects of the present invention are not impaired and the scale preventing action is not impaired. As the inorganic compound, for example,
Silicic acids such as orthosilicic acid, metasilicic acid, mesosilicic acid, mesotrisilicic acid, mesotetrasilicic acid, sodium metasilicate, sodium orthosilicate, sodium disilicate, sodium tetrasilicate, sodium metasilicate, water glass, etc.,
Or silicates; alkaline earth metals such as calcium,
Metal compounds such as oxyacid salts, acetate salts, nitrate salts, hydroxides or halides of metals selected from zinc group metals such as zinc, aluminum metals such as aluminum, and platinum group metals such as platinum; ferric hydroxide It is an inorganic colloid such as colloid, silicic acid colloid, barium sulfate colloid, and aluminum hydroxide colloid. These colloids can be prepared, for example, by mechanical grinding, ultrasonic irradiation, electrical dispersion and chemical methods.

Formation of coating film The coating liquid is applied to the inner wall of the polymerization vessel, dried sufficiently, and further washed with water as necessary to form a coating film having a polymer scale adhesion preventing effect. In this case, the drying may be performed within a temperature range of room temperature to 100 ° C, for example. The coating solution is preferably applied to the portion other than the inner wall surface of the polymerization vessel as long as the monomer comes into contact during polymerization, for example, a stirring blade, a stirring shaft, a condenser, a header, a search coil, a bolt, a nut, and the like. It is better to apply it. More preferably, the coating liquid is applied to the portion where the polymer scale in the recovery system of the unreacted monomer may adhere, for example, the inner surface of the monomer distillation column, the condenser, the monomer storage tank, the valve and the like. The coating film thus formed can prevent the formation of the polymer scale even in these portions.

There is no particular limitation on the method of applying the coating liquid to the inner wall surface of the polymerization vessel. For example, a brush coating method, a spray coating method, a method of filling the polymerization vessel with the coating solution, and then withdrawing the coating solution can be used. No. 57-61001, No. 55-3628
No. 8, JP-B-56-501116, JP-B-56-501117, JP-A-59
The automatic coating method described in No. 11303 or the like can also be used.

The method of drying the surface in a wet state by applying the coating solution is not limited, either.
For example, the following method can be used. That is, after applying the coating liquid, a method of applying an appropriately heated hot air to the coating surface, or the inner wall surface of the polymerization vessel and the other surface to be coated with the coating liquid are preheated to, for example, 30 to 80 ° C., A method of directly applying the coating liquid to the heated surface can be used. And after drying the coated surface,
The coated surface is washed with water as needed.

The coating film thus obtained has a total coating amount of the basic polysaccharide or basic polysaccharide and tannins of usually 0.001 g / m ² or more, particularly 0.05 to ² g / m ² . Preferably there is. The coating operation may be performed for each batch of polymerization. However, the coating film formed once has considerable durability and maintains the action of preventing adhesion of the polymer scale. No need to do it.
Usually, the coating film may be formed in batches of 1 to 10 or more.

Polymerization As described above, after the inner wall of the polymerization vessel and, preferably, other portions where the monomers come into contact with each other during the polymerization are subjected to a coating treatment to form a coating film, they are usually kept in the polymerization vessel. Polymerization is carried out according to the method. That is, a monomer having an ethylenic double bond, and a polymerization medium used as necessary and a dispersing aid for dispersing the monomer are charged, and then polymerization is performed according to a conventional method. .
Examples of the monomer having an ethylenic double bond to which the method of the present invention is applied include vinyl halides such as vinyl chloride, vinyl acetate, vinyl esters such as vinyl propionate, acrylic acid, methacrylic acid, and the like. Ester or salt, maleic acid or fumaric acid, and their ester or anhydride, butadiene, chloroprene, diene monomers such as isoprene, aromatic vinyl compounds such as styrene, acrylonitrile, vinylidene halide, vinyl ether, etc. Is mentioned. Further, the type of polymerization to which the method of the present invention is applied is not particularly limited, and is effective in any of the polymerization types of suspension polymerization, emulsion polymerization, solution polymerization, bulk polymerization and gas phase polymerization, and particularly suspension. Suitable for polymerization in aqueous media such as polymerization and emulsion polymerization.

More specifically, in the case of suspension polymerization and emulsion polymerization, the polymerization is generally carried out, for example, by charging water and a dispersion aid in a polymerization vessel, then charging a polymerization initiator, and then, Exhaust the inside of the polymerization vessel from about 0.1 mmHg to about 760 mmHg
The pressure is reduced to, and the monomer is charged (the internal pressure of the polymerization vessel is usually 0.5 to
30 kg · cm ^-2 ), if necessary, by adding water, one or more of a dispersion aid and a polymerization initiator during the polymerization. The polymerization temperature is usually in the range of 30 to 150 ° C, for example, 30 to 80 ° C for vinyl chloride polymerization,
In the polymerization of styrene, the temperature may be 50 to 150 ° C. The polymerization is carried out when the internal pressure of the polymerization vessel has dropped to about 0 to 7 kg · cm ^-2 or when the difference between the temperature of the inlet and outlet of the cooling water of the jacket provided in the polymerization vessel has almost disappeared ( That is, it is determined that the process is completed when the heat generated by the polymerization reaction is eliminated. In this case, water is usually used in a proportion of about 100 to 500 parts by weight with respect to 100 parts by weight of the monomer, the dispersion aid is about 0.01 to 30 parts by weight, and the polymerization initiator is about 0.01 to 5 parts by weight. Used in proportion.

In the case of solution polymerization, an organic solvent such as toluene, xylene or pyridine is used as the polymerization medium instead of water. A dispersion aid is used as needed. Other conditions are generally the same as those for suspension polymerization and emulsion polymerization. In the case of bulk polymerization, after the inside of the polymerization vessel is evacuated to a pressure of about 0.01 mmHg to about 760 mmHg, monomers are charged and polymerization is carried out at -10 ° C to 250 ° C. The method of the present invention is effective regardless of the material such as the inner wall of the polymerization vessel,
For example, the present invention is also effective for a polymerization vessel made of stainless steel or other steel, a glass-lined polymerization vessel, and the like.

What is added to the polymerization system can be used without any restrictions. That is, for example, t-butyl peroxy neodecanoate, bis (2-ethylhexyl) peroxydicarbonate, 3,5,5-trimethylhexanoyl peroxide, α-cumylperoxy neodecanoate, cumene hydroper Oxide, cyclohexanone peroxide, t-butyl peroxypivalate, bis (2-ethoxyethyl) peroxy dicarbonate, benzoyl peroxide, lauroyl peroxide, 2,4-dichlorobenzoyl peroxide, diisopropyl peroxydicarbonate,
α, α'-azobisisobutyronitrile, α, α'-azobis-2,4-dimethylvaleronitrile, potassium peroxodisulfate, ammonium peroxodisulfate, p-
Polymerization catalysts such as menthane hydroperoxide; partial oxides of polyvinyl acetate, polyacrylic acid, copolymers of vinyl acetate and maleic anhydride, cellulose derivatives such as hydroxypropylmethyl cellulose, natural or synthetic polymer compounds such as gelatin, etc. Suspension agents; solid dispersants such as calcium phosphate and hydroxyapatite; nonionic emulsifiers such as sorbitan monolaurate, sorbitan trioleate and polyoxyethylene alkyl ethers;
Anionic emulsifiers such as sodium alkylbenzene sulfonate such as sodium lauryl sulfate and sodium dodecylbenzene sulfonate, sodium dioctyl sulfosuccinate; fillers such as calcium carbonate and titanium oxide;
Stabilizers such as tribasic lead sulfate, calcium stearate, dibutyltin dilaurate and dioctyltin methylcaptide; lubricants such as rice wax, stearic acid and cetyl alcohol; plasticizers such as DOP and DBP; chain transfer agents such as trichloroethylene and mercaptans. The method of the present invention can effectively prevent the adhesion of polymer scale even in a polymerization system in which a pH adjuster or the like is present.

The above-mentioned polymer scale inhibitor used in the present invention may be used for forming a coating film on the inner wall surface of the polymerization vessel or may be directly added to the polymerization system. With this, the effect of preventing the adhesion of the polymer scale can be expected. In this case, the addition amount of the polymerization inhibitor is appropriately about 10 ppm to 1000 ppm based on the total weight of the charged monomers. Care should be taken not to affect the quality of the product polymer, such as fisheye, bulk specific gravity, and particle size distribution.

[0025]

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples. In each of the following tables, an experiment number marked with * is a comparative example, and other experiment numbers are examples.

Example 1 Polymerization was carried out as follows using a stainless steel polymerization vessel equipped with a stirrer and having an internal volume of 1000 liters. In each experiment,
As shown in Table 2, a water-soluble basic polysaccharide or a water-soluble basic polysaccharide and tannins was dissolved in a solvent to a concentration shown in Table 2 to prepare a coating solution. Then, this coating solution is applied to the inner wall of the above-mentioned stainless steel polymerization vessel equipped with a stirrer, a stirrer shaft, a stirrer and other portions where the monomer comes into contact, and heated at 60 ° C. for 15 minutes to dry, thereby forming a coating film , Washed with water. However, in Experiment No. 101 of the comparative example, the coating liquid was not applied at all. Table 2 shows (A) water-soluble basic polysaccharides and (B) tannins used in each experiment, the total concentration thereof, the use ratio (A) / (B) [weight ratio] of these components, and the solvent. Next, in a polymerization vessel having a coating film formed by applying a coating treatment in this way, 400 kg of water, 200 kg of vinyl chloride,
Partially saponified polyvinyl alcohol 250g, hydroxypropyl methylcellulose 25g and diisopropyl peroxydicarbonate 75g were charged and stirred at 57 ° C.
It was polymerized for 6 hours. After completion of the polymerization, the amount of polymer scale attached to the inner wall surface of the polymerization vessel was measured. Further, the degree of coloring of the polymer obtained in each experiment was measured by the following method.

100 parts by weight of polymer, 1 part by weight of TS-101 stabilizer (manufactured by Akishima Chemical Co., Ltd.) and C-100J (manufactured by Katsuta Kako Co., Ltd.)
After kneading 0.5 parts by weight and 50 parts by weight of plasticizer DOP for 5 minutes at 160 ° C using a two-roll mill, the thickness is 1 mm.
Was formed into a sheet. Next, this sheet is 4 cm x 4 cm x
Put in a mold of 1.5 cm (thickness), 160 ℃, 65-70 kg / cm ²
A sample for measurement was prepared by heating and press molding with. For this measurement sample, the lightness index L in the Hunter color difference formula described in JIS Z8730 (1980) was determined, and the larger the L value, the higher the whiteness.

The L value was determined as follows. JIS Z
According to the description of 8722, using standard light C, photoelectric colorimeter (Nippon Denshoku Industries Co., Ltd. Z-1001DP type colorimetric color difference meter),
The stimulus value Y of the XYZ color system was determined by the stimulus value direct reading method. The geometric conditions for illumination and light reception are JIS Z 8722.
The condition d described in Section 4.3.1 is adopted. Next, JIS
L was determined by the formula described in Z 8730 (1980): L = 10Y ^1/2 . The closer the L value is to 100, the higher the whiteness and the lower the degree of coloring. Table 2 shows the results. Each chitosan used has the viscosity and the degree of deacetylation shown in Table 1, and the supplier is also described.

[0029]

[Table 1]

[0030]

[Table 2]

Example 2 In each experiment, first, as shown in Table 3, water-soluble basic polysaccharides, or water-soluble basic polysaccharides and tannins were dissolved in a solvent under the conditions shown in Table 3 and applied. A liquid was prepared. Then, in the same manner as in Example 1, this coating solution was applied to the inner wall of a stainless steel polymerization vessel equipped with a stirrer and having an internal volume of 20 liters to form a coating film. In the polymerization vessel thus formed with the coating film, 9 kg of water, 225 g of sodium dodecylbenzenesulfonate, 12 g of t-dodecyl mercaptan, and 13 g of potassium persulfate were charged, and after nitrogen substitution, styrene was added.
1.3 kg and 3.8 kg of butadiene were charged and then polymerized at 50 ° C. for 20 hours while stirring. After the completion of the polymerization, the amount of polymer scale adhered on the inner wall surface of the weight was examined. The results are shown in Table 3.

[0032]

[Table 3]

[0033]

EFFECTS OF THE INVENTION According to the present invention, it is possible to effectively prevent the adhesion of polymer scale, and it is possible to produce a product polymer having a high whiteness with an L value of 70 or more.
Moreover, the scale inhibitor used has no toxicity or the like and is highly safe, so that there is no problem in terms of safety and health of workers. Furthermore, according to the present invention, regardless of various conditions of the polymerization such as the type of the monomer and the polymerization initiator used, the polymerization mode, the material of the inner wall of the polymerization vessel, etc., the adhesion of the polymer scale is effectively prevented. can do. That is, for example, even in emulsion polymerization in which it is difficult to prevent adhesion of the polymer scale, even in the case where a stainless steel polymerization vessel to which the polymer scale is easily attached is used, or potassium oxysulfate having strong oxidizing power is used as a polymerization initiator. When used as a polymer, the adhesion of the polymer scale can be effectively prevented. Therefore, when the polymerization is carried out by applying the present invention, it is not necessary to carry out the polymer scale removal work for each polymerization, thereby improving the productivity and producing a high quality product polymer without coloring. Can be produced.

Claims (2)

(57) [Claims] 1. A method for preventing adhesion of polymer scale in the polymerization of a monomer having an ethylenic double bond in a polymerization vessel, which comprises coating a water-soluble basic polysaccharide on the inner wall surface of the polymerization vessel in advance. A method for preventing adhesion of polymer scale, which comprises performing the above polymerization in a polymerization vessel in which a film is formed. 2. A polymer scale inhibitor used for the polymerization of a monomer having an ethylenic double bond, which contains a water-soluble basic polysaccharide.