JPH05178909A - Inhibitor for preventing polymer scale deposition, polymerizer, and production of polymer using these - Google Patents

Abstract

(57) [Summary] [Structure] A polymer scale adhesion preventive agent for the polymerization of a monomer having an ethylenically unsaturated bond, which comprises (A) gelatin and (B) an alkali metal silicate. A polymerization vessel in which a coating film comprising the inhibitor is formed on the inner wall, and a scale prevention method using the polymerization vessel. [Effects] Adhesion of polymer scale can be effectively prevented, and a product polymer having a high whiteness of L value of 70 or more can be produced. Moreover, the polymer scale adhesion preventive agent of the present invention has no toxicity and is highly safe.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer scale anti-adhesion agent for polymerization of a monomer having an ethylenically unsaturated bond, a polymerization vessel, and a method for producing a polymer using the same.

[0002]

2. Description of the Related Art In a method for producing a polymer by polymerizing a monomer in a polymerization vessel, it is known that the polymer adheres to the inner wall surface of the polymerization vessel as a scale. If polymer scale adheres to the inner wall surface of the polymerization vessel, the yield of the polymer will decrease, the cooling capacity of the polymerization vessel will decrease, and the quality of the product polymer will deteriorate due to the adhered polymer scale peeling off and mixing into the product. And the like, and further disadvantageous in that much labor and time are required for removing the polymer scale. Moreover, since the polymer scale contains unreacted monomers, it can expose workers to physical damage.

Conventionally, in the polymerization of monomers having an ethylenically unsaturated bond, as a method for preventing the adhesion of the polymer scale to the inner wall surface of the polymerization vessel or the like, an appropriate substance is used as the polymer scale adhesion preventing agent. A method of applying to the inner wall surface is known. Examples of the substance suitable as the polymer scale anti-adhesion agent include a specific polar compound (Japanese Patent Publication
45-30343), dye or pigment (Japanese Patent Publication No. 45-30835)
No. 52-24953), aromatic amine compounds (JP-A-51)
No. 50887), a reaction product of a phenolic compound with an aromatic aldehyde, and the like (JP-A-55-54317).

[0004]

By the way, the vinyl chloride polymer obtained by the polymerization is required to have a high whiteness, for example, the lightness index in the color difference formula of Hunter described in JIS Z 8730 (1980). The value of L is required to be 70 or more. Conventional polymer scale anti-adhesive agents include dyes or pigments described in JP-B-45-30835 and JP-B-52-24953, aromatic amine compounds described in JP-A-51-50887, and JP-A-55. Many are colored, as represented by the reaction product of the phenolic compound and aromatic aldecht described in No. 54317. Presumably because of this, a colored polymer is obtained by carrying out suspension polymerization of vinyl chloride or the like in a polymerization vessel having a coating film made of these scale inhibitors. That is, for example, when the lightness index L is measured, a value of 65 or less is obtained, and coloring is confirmed. It is considered that this coloring occurs as a result of the components of the coating film being mixed into the polymerization system due to dissolution or peeling of the coating film. Improvements are also required to improve the quality of polymers.

Further, conventional polymer scale anti-adhesion agents are described in JP-B-45-30343, which are deleterious substances such as aniline, nitrobenzene and formaldehyde, which are exemplified as polar compounds in JP-B-45-30343. Many of them are toxic, as represented by those containing heavy metals such as chromium and lead, which are exemplified as the pigments. In addition, Japanese Patent Publication Sho 45
Among the dyes described in −30835 and Japanese Examined Patent Publication No. 52-24953, some may be carcinogenic. Therefore, when these substances are used, there is a safety problem for workers.

[0006]

The object of the present invention is to effectively prevent the adhesion of polymer scale, and to obtain a polymer having high whiteness because the polymer is not colored. Moreover, it is an object of the present invention to provide a polymer scale anti-adhesion agent and a method for preventing the adhesion of polymer scale, which has no toxicity or the like and has no safety or health concern. That is, the present invention, as for achieving the above object, (A) gelatin and (B) containing a silicate of an alkali metal, polymer scale deposition for the polymerization of a monomer having an ethylenically unsaturated bond Provide an inhibitor.

The present invention also provides a polymerization vessel for polymerizing a monomer having an ethylenically unsaturated bond, which has a coating film containing (A) gelatin and (B) an alkali metal silicate on the inner wall surface. I will provide a.

Further, the present invention provides a method for producing a polymer, which comprises a step of polymerizing a monomer having an ethylenically unsaturated bond in a polymerization vessel having a coating film made of a polymer scale inhibitor on the inner wall surface. And a polymer scale inhibitor, which comprises (A) gelatin and (B) an alkali metal silicate.

According to the polymer scale adhesion preventive agent of the present invention, and the polymerization vessel and polymer production method using the same,
Not only is polymer scale effectively prevented, but a product polymer having a high whiteness with an L value of 70 or more can be produced. Moreover, the polymer scale anti-adhesion agent used has no toxicity and is highly safe, so there is no problem in terms of worker health and safety.

(A) Gelatin Gelatin is a kind of inducible protein obtained from collagen, and the triple helix structure of collagen is broken, that is, denatured (denatured collagen). Commercially available gelatin is glutamine, NH of the amide group of asparagine.
_{Although 2} is a mixture of blunt or covalently cleaved, such denatured collagen can also be used as the gelatin of the present invention. Also, JIS K 65
In 03, 1 to 5 types of gelatin classified by viscosity, jelly strength and the like measured under specified conditions are described, and any of these can be used. Gelatin can be obtained, for example, by pre-treating collagen with an acid or alkali and then heat-treating it. Collagen is generally water insoluble, while gelatin is water soluble.

(B) Alkali metal silicate Examples of the alkali metal silicate include lithium and
Alkali metal metasilicates such as sodium and potassium (M ₂ SiO ₃ ), orthosilicates (M ₄ SiO ₄ ), disilicates (M ₂ Si ₂ O ₅ ), trisilicates (M ₃ Si _3). O
₇ ), sesquisilicic acid (M ₄ Si ₃ O ₁₀ ), etc.
M represents an alkali metal such as lithium, sodium or potassium), and water glass. These can be used alone or in combination of two or more.

Other Components In addition to the components (A) and (B) described above, the polymer scale anti-adhesion agent of the present invention may contain, if necessary, a solvent, a cationic surfactant and a nonion. A surface active agent, an anionic surface active agent, etc. can be added. The polymer scale adhesion preventive agent of the present invention is, for example, formed as a coating film on the inner wall surface of the polymerization vessel or the like to prevent the scale from adhering to the inner wall surface of the polymerization vessel or the like. Normal,
When the coating film is formed on the inner wall surface of the polymerization vessel, it is used as a solution, that is, as a coating liquid.

Preparation of coating liquid The coating liquid as described above is prepared by dissolving the above-mentioned component (A) in hot water, cooling the solution to room temperature, and then adding the component (B) thereto. .. Examples of the solvent used for preparing such a coating liquid include water; methanol, ethanol, propanol, butanol, 2-butanol,
2-methyl-1-propanol, 2-methyl-2-propanol, 3-methyl-1-butanol, 2-methyl-
Alcohol solvents such as 2-butanol and 2-pentanol; Ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone; Ester solvents such as methyl formate, ethyl formate, methyl acetate and methyl acetoacetate; 4-
Ether-based solvents such as methyldioxolane and ethylene glycol diethyl ether; furans; aprotic solvents such as dimethylformamide, dimethylsulfoxide and acetonitrile. These are appropriately used alone or as a mixed solvent of two or more kinds.

The total concentration of the components (A) and (B) in the coating solution is the preferred coating amount described later, that is, per unit area.
It is not particularly limited as long as the total weight of the component (A) and the component (B) is obtained, but it is usually 0.005 to 10% by weight, preferably 0.
It is about 01 to 5% by weight. In addition, (A) component in the coating liquid
The content ratio of the component (B) is usually 0.1 to 1000 parts by weight, preferably 1 to 600 parts by weight, per 100 parts by weight of the component (A). If the amount of the component (B) is too large or too small as compared with the amount of the component (A), the effect of preventing the scale from adhering by using the components (A) and (B) together may not be obtained. The pH of the coating solution is not particularly limited. If necessary, an appropriate acid or alkali may be appropriately selected and used as the pH adjuster.

Formation of coating film To form a coating film on the inner wall surface of the polymerization vessel using the coating solution prepared as described above, first, the coating solution is applied to the inner wall surface of the polymerization vessel, and then, for example, at room temperature. After thoroughly drying in the temperature range from 1 to 100 ° C, further wash with water if necessary. By doing so, a coating film is formed on the inner wall surface of the polymerization vessel, so that adhesion of the polymer scale to the inner wall surface of the polymerization vessel is prevented.

The coating solution is preferably applied not only to the inner wall surface of the polymerization vessel, but also to other portions with which the monomer contacts during the polymerization, thereby forming a coating film. .. For example, it is better to form a coating film on the stirring blade, stirring shaft, baffle, condenser, header, search coil, bolt, nut, etc. by applying the above-mentioned coating liquid.
In particular, the stirring blade, stirring shaft and baffle should normally be coated with the coating solution to form a coating film. In order to form a coating film by applying the coating liquid to these portions, it may be carried out in the same manner as in the case of forming the coating film on the inner wall of the polymerization vessel.

More preferably, the coating liquid is a site other than the site where the monomer comes into contact during the polymerization, where polymer scale may be attached, for example, a device of a recovery system of unreacted monomer. It is preferable that the coating liquid is applied to the inner surface of the pipe and the like to form a coating film. More specifically, as such a part, a monomer distillation column, a condenser,
The inner surface of the monomer storage tank, valve, etc. may be mentioned. The coating film may be formed at these portions as in the case of forming the coating film on the inner wall of the polymerization vessel.

In this way, when a coating film is formed on the site where the monomer contacts during the polymerization and the site where the other polymer scale may adhere, the adhesion of the polymer scale to those sites. Is prevented. The method of applying the coating liquid to the inner wall surface of the polymerization vessel is not particularly limited, and for example,
Other methods include brush coating, spray coating, and the method of withdrawing after filling the polymerization vessel with the coating solution.
No. 61001, No. 55-36288, No. 56-501116, No. 56
It is also possible to use the automatic coating method described in JP-A-501117, JP-A-59-11303 and the like.

The method of drying the wet surface by applying the coating liquid is not limited, either.
For example, the following method can be used. That is, after applying the coating liquid, a method of applying a suitably heated warm 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 coating amount per unit area, that is, the total weight of the component (A) and the component (B) per unit area is usually
0.001 g / m ² or more, and particularly preferably 0.05 to 2 g / m ^2. The above coating operation may be performed every 1 to 10 or more batches of polymerization. The formed coating film has high durability,
The polymer scale does not always need to be carried out for each batch of polymerization, since the action of preventing adhesion of the polymer scale continues. For this reason,
Product polymer productivity is improved.

The polymer scale anti-adhesion agent of the present invention can also be added to the polymerization medium. In that case, for example, the coating liquid may be used for the coating treatment, and then a small amount of the polymer scale adhesion inhibitor in the same solution state as the coating liquid may be added to the polymerization medium. If you do this,
The scale prevention effect is improved as compared with the case where only the coating process is performed. When such a polymer scale anti-adhesion agent in a solution state is added to the polymerization medium, the amount added is in the range of 5 to 1000 ppm based on the total weight of the charged monomers having an ethylenically unsaturated bond. Just do it.

Polymerization As described above, a coating film is formed by applying a coating treatment to the inner wall of the polymerization vessel, and preferably to other portions where the monomer contacts during the polymerization, and then, in a usual manner in the polymerization vessel. Polymerize. That is, in addition to a monomer having an ethylenically unsaturated bond and a polymerization initiator (catalyst), if necessary, a polymerization medium such as water, and a suspending agent, a solid dispersant, a nonionic or anionic emulsifier, etc. A dispersant and the like are charged, and then polymerization is performed by a conventional method.

Examples of the monomer having an ethylenically unsaturated bond which is polymerized by applying the method of the present invention include vinyl halides such as vinyl chloride; vinyl esters such as vinyl acetate and vinyl propionate; acrylic acid. , Methacrylic acid, and their esters or salts; maleic acid,
Fumaric acid and esters or anhydrides thereof; diene monomers such as butadiene, chloroprene and isoprene; styrene, acrylonitrile, vinylidene halide, vinyl ether and the like. Further, the form of polymerization to which the method of the present invention is applied is not particularly limited, and is effective in any of the polymerization forms of suspension polymerization, emulsion polymerization, solution polymerization, bulk polymerization and gas phase polymerization, and particularly suspension. It is more suitable for polymerization in an aqueous medium such as polymerization and emulsion polymerization.

A general polymerization method will be specifically described below by taking the cases of suspension polymerization and emulsion polymerization as examples. First, water and a dispersant are charged into a polymerization vessel, and then a polymerization initiator is charged. Next, evacuate the inside of the polymerization vessel to 0.1 ~ 760 mm
After reducing the pressure to Hg, charge the monomer (at this time, the internal pressure of the polymerization vessel is usually 0.5 to 30 kgf / cm ² · G), and then 30
Polymerize at reaction temperature of ~ 150 ° C. During the polymerization, one or more kinds of water, a dispersant and a polymerization initiator are added, if necessary. Further, the reaction temperature during the polymerization depends on the type of monomer to be polymerized, for example, in the case of vinyl chloride polymerization is carried out at 30 ~ 80 ℃, in the case of styrene polymerization 50 ~ 150 ℃. Polymerize with. Polymerization has almost no difference between the inlet temperature and the outlet temperature of the cooling water that flows in and out when the internal pressure of the polymerization vessel drops to 0 to 7 kgf / cm ² · G or into the jacket equipped around the polymerization vessel. When the temperature rises (that is, when the heat generated by the polymerization reaction disappears),
It is judged to have been completed. Water, a dispersant, and a polymerization initiator charged at the time of polymerization are usually 20 to 500 parts by weight of water, 0.01 to 30 parts by weight of a dispersant, and 0.01 to 5 parts by weight of a polymerization initiator with respect to 100 parts by weight of a monomer. It is a department.

In the case of solution polymerization, an organic solvent such as toluene, xylene or pyridine is used as a polymerization medium instead of water. A dispersant is used as needed. Other polymerization conditions are generally the same as those for suspension polymerization and emulsion polymerization.

In the case of bulk polymerization, the inside of the polymerization vessel is
After evacuating to a pressure of 0.01 to 760 mmHg, a monomer and a polymerization initiator are charged in the polymerization vessel, and polymerization is carried out at a reaction temperature of -10 ° C to 250 ° C. For example, in the case of vinyl chloride polymerization
It is carried out at 30 to 80 ° C and in the case of styrene polymerization at 50 to 150 ° C. When the polymerization is carried out by applying the method for preventing adhesion of the polymer scale of the present invention, the adhesion of the polymer scale can be prevented regardless of the material such as the inner wall surface of the polymerization vessel. The adhesion of polymer scale can be prevented even when the polymerization is carried out in a steel-made polymerization vessel, a glass-lined polymerization vessel or 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 initiators such as menthane hydroperoxide; partially saponified polyvinyl alcohol, polyacrylic acid, copolymers of vinyl acetate and maleic anhydride, cellulose derivatives such as hydroxypropylmethyl cellulose, and natural or synthetic polymer compounds such as gelatin. Suspending agents; solid dispersants such as calcium phosphate and hydroxyapatite; nonionic emulsifiers such as sorbitan monolaurate, sorbitan trioleate and polyoxyethylene alkyl ethers; sodium alkylbenzenesulfonates such as sodium lauryl sulfate and sodium dodecylbenzenesulfonate; dioctyl. Anionic emulsifiers such as sodium sulfosuccinate; fillers such as calcium carbonate and titanium oxide; tribasic lead sulfate, calcium stearate, dibutyltin dilaurate Stabilizers such as dioctyltin methylcaptide; lubricants such as rice wax, stearic acid and cetyl alcohol; plasticizers such as DOP and DBP; mercaptans such as t-dodecyl mercaptan; chain transfer agents such as trichloroethylene; and pH adjusters. Even in existing polymerization systems, the process of the present invention can effectively prevent polymer scale deposition.

[0027]

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples. In addition, in each of the following tables, the experimental numbers marked with * are comparative examples, and the other experimental numbers are examples of the present invention. In the following examples, the gelatin shown in Table 1 was used.

[0028]

[Table 1]

Example 1 Polymerization was carried out in the following manner using a stainless steel polymerization vessel equipped with a stirrer and having an internal volume of 1000 liters. In each experiment, first, the component (A) and the component (B) were dissolved in a solvent so that the total concentration as shown in Table 2 was obtained to prepare a coating solution. These coating solutions were applied to the inner wall of the polymerization vessel, the stirring shaft, the stirring blades, and other portions where the monomers come into contact with each other during the polymerization. However, the experiment
No. 101 to 103 do not apply the coating liquid, or (A)
It is a comparative example in which a coating liquid containing only one of the component and the component (B) was applied. Types of (A) gelatin and (B) alkali metal silicate in the coating solution used in each experiment, total concentration and weight ratio of (A) + (B) in the coating solution
Table 2 shows (A) / (B) and the type of solvent used.

Then, 400 kg of water, 200 kg of vinyl chloride, 250 g of partially saponified polyvinyl alcohol, 25 g of hydroxypropylmethylcellulose and 25 g of bis (2-ethylhexyl) were placed in the polymerization vessel where the coating film was formed by the coating treatment as described above. 75 g of peroxydicarbonate was charged and polymerized at 57 ° C. for 6 hours while stirring. After the polymerization was completed, the amount of polymer scale attached to the inner wall of the polymerization vessel was measured. Also, each experiment
The whiteness of the polymer obtained in No. was measured by the following method. 100 parts by weight of polymer, tin stabilizer TS-101 (trade name,
Akishima Chemical Co., Ltd.) 1 part by weight and cadmium stabilizer C-10
0.5 parts by weight of 0J (trade name, manufactured by Katsuta Kako Co., Ltd.) and 50 parts by weight of plasticizer DOP at 5 ° C. at 160 ° C. using a two roll mill
After kneading for a minute, a sheet having a thickness of 1 mm was formed. next,
This sheet was put in a 4 cm × 4 cm × 1.5 cm (thickness) mold and heated and pressed at 160 ° C. and 65 to 70 kgf / cm ² to prepare a measurement sample. Regarding this measurement sample, JIS Z 87
The lightness index L in the Hunter color difference formula described in 30 (1980) was determined, and the larger the L value, the higher the whiteness.

The L value was determined as follows. JIS Z 8722
The standard value C, photoelectric colorimeter (Z-1001DP type colorimetric color difference meter manufactured by Nippon Denshoku Industries Co., Ltd.) was used to determine the stimulus value Y of the XYZ color system by the stimulus value direct reading method. The geometric conditions for illumination and reception are JIS Z 8722 4.
The condition d described in Section 3.1 was adopted. Next, JIS Z 8730 (1
980), L was determined by the formula: L = 10Y ^1/2 . The results are shown in Table 2.

[0032]

[Table 2]

Example 2 (A) Gelatin and (B) Type of alkali metal silicate used in a stainless steel polymerization vessel equipped with a stirrer having an internal volume of 20 liters, total concentration and weight of (A) + (B) Ratio (A) / (B)
, And the coating liquid was used in the same manner as in Example 1 except that the type of solvent used was as shown in Table 3. However, Experiment Nos. 201 to 203 are comparative examples in which the coating liquid was not applied or the coating liquid containing only one of the component (A) and the component (B) was used. Next, in the polymerization vessel thus coated, water 9
kg, sodium dodecylbenzenesulfonate 225 g, t
-Charging 12 g of dodecyl mercaptan and 13 g of potassium peroxodisulfate and purging with nitrogen gas, styrene 1.3
kg and 3.8 kg of butadiene were charged and polymerized at 50 ° C. for 20 hours. After the completion of the polymerization, the amount of polymer scale attached on the inner wall surface of the polymerization vessel was measured. The results are shown in Table 3.

[0034]

[Table 3]

[0035]

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 of L value of 70 or more.
Moreover, the polymer scale anti-adhesion agent of the present invention has no toxicity or the like and is highly safe, so that there is no problem in terms of worker health and safety. Further, according to the present invention, the adhesion of polymer scale is effectively prevented regardless of the 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. can do.

[Procedure amendment]

[Submission date] October 28, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction content]

Other Components The polymer scale anti-adhesion agent of the present invention includes the above-mentioned (A),
In addition to both components (B), if necessary, a solvent, a cationic surfactant, a nonionic surfactant, an anionic surfactant, etc. can be added. The polymer scale adhesion preventive agent of the present invention is, for example, formed as a coating film on the inner wall surface of the polymerization vessel or the like to prevent the scale from adhering to the inner wall surface of the polymerization vessel or the like. Usually, when the coating film is formed on the inner wall surface of the polymerization vessel, it is used in a solution state, that is, as a coating liquid.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0028

[Correction method] Change

[Correction content]

[0028]

[Table 1]

Claims (3)

[Claims] 1. A polymer scale anti-adhesion agent for the polymerization of a monomer having an ethylenically unsaturated bond, which comprises (A) gelatin and (B) an alkali metal silicate. 2. A polymerization vessel for polymerizing a monomer having an ethylenically unsaturated bond, having a coating film containing (A) gelatin and (B) an alkali metal silicate on the inner wall surface. 3. A monomer having an ethylenically unsaturated bond,
In the method for producing a polymer having a step of polymerizing in a polymerization vessel having a coating film made of a polymer scale inhibitor on the inner wall surface, the polymer scale inhibitor is (A) gelatin and (B) an alkali metal A method for producing, characterized in that it contains a silicate.