JPH04108805A - Agent for preventing deposition of polymer scale and method for preventing deposition thereof - Google Patents

Abstract

PURPOSE:To provide the subject preventing agent containing a natural naphthoquinone pigment and a polysaccharide, etc., effective in preventing the deposition of polymer scale in the polymerization of a vinyl chloride monomer, causing little discoloration of produced polymer and giving a molded article having little fish-eye. CONSTITUTION:The objective preventing agent contains (A) a natural naphthoquinone pigment (preferably shikonin or naphthazarin) and (B) a polysaccharide (preferably amylose, amylopectin, oxidized starch, CMC, etc.) and/or a lignin (e.g. alcohol lignin). The agent is applied to the inner wall surface of a polymerizer.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention provides a polymer scale adhesion inhibitor for the polymerization of vinyl chloride monomer or a monomer mixture mainly composed of vinyl chloride, and a polymer scale adhesion prevention agent. Regarding prevention methods.

[Conventional technology]

BACKGROUND ART In a method of producing a polymer by polymerizing monomers in a polymerization vessel, there is a known problem that the polymer adheres as scale to the inner wall surface of the polymerization vessel.

When polymer scale adheres to the inner wall surface of the polymerization vessel, the yield of the polymer decreases, the cooling capacity of the polymerization vessel decreases, and the quality of the product polymer decreases due to the adhered polymer scale peeling off and contaminating the product. In addition, there are disadvantages such as a great deal of effort and time required to remove the polymer scale. Moreover, the polymer scale contains unreacted monomers, which can expose workers and cause physical injury.

Conventionally, in the polymerization of monomers having ethylenic double bonds, the method of preventing polymer scale from adhering to the inner wall surface of the polymerization vessel, etc. is to use a suitable substance as a polymer scale adhesion inhibitor. There is a known method of applying it to

Substances suitable as polymer scale adhesion inhibitors include:
For example, there are dyes and pigments described in Japanese Patent Publication No. 45-30835.

[Problem to be solved by the invention]

By the way, recently, molded products of vinyl chloride polymers, especially transparent sheets, bottles, etc., have been improved in terms of appearance and mechanical properties, such as degree of coloration, fish eyes, bulk specific gravity, gelation rate, initial coloration, and thermal stability. Demand from users for quality improvements in various physical properties such as properties is increasing. Therefore, it is desired to develop a polymer scale adhesion inhibitor that does not adversely affect the physical properties of the resulting polymer.

However, when the above dyes and pigments are used as polymer scale adhesion inhibitors, the following (i) and (ii)
), it has an adverse effect on the physical properties of the product polymer.

(i) Since the coating film made of the polymer scale adhesion inhibitor is easily dissolved, the resulting product polymer may be colored or its bulk specific gravity may be reduced.

(11) Due to the weak adhesion of the coating film to the inner wall surface of the polymerization vessel, the coating film peels off and partially disappears during polymerization, and scale adheres there, resulting in the resulting polymer being transferred to sheets, etc. When processed into molded products, it causes an increase in fins eye.

[Means to solve the problem]

The object of the present invention is to be able to always effectively prevent the adhesion of polymer scale in the polymerization or copolymerization of vinyl chloride or a monomer mixture mainly composed of vinyl chloride, and to have a significantly low degree of coloration. Another object of the present invention is to provide a polymer scale adhesion inhibitor and a method for preventing polymer scale adhesion, which can obtain a high-quality product polymer with very little fins in a molded article.

That is, the present invention achieves the above object by using a vinyl chloride monomer or vinyl chloride containing at least one member selected from the group consisting of (A) naphthoquinone natural pigments and CB) polysaccharides and lignins. A polymer scale anti-adhesion agent for polymerization of a monomer mixture based on the present invention is provided.

The present invention also provides a method for preventing the adhesion of polymer scale during polymerization of a vinyl chloride monomer or a monomer mixture mainly composed of vinyl chloride in a polymerization vessel, the method comprising: Provided is a method for preventing the adhesion of polymer scale, which comprises the step of carrying out the polymerization in a polymerization vessel in which a coating film containing both the components (^) and (B) is formed.

(A phthoquinone) The naphthoquinone natural pigment which is the component (A) of the polymer scale adhesion inhibitor of the present invention is 6-methyl-14-
Naphthoquinone, 2-methyl-1,4-naphthoquinone, Lawsone, Nigerone, Plumbagin, Alcannin, Equituchrome A, Subinochrome A, Vitamin 1, Vitamin 2, Naphthazarin, 2,3-Dihydroxynaphthazarin, 2-Methylnaphtha Zarin, 2-hydroxynaphthazarin, 2-hydroxy-3-methylnaphthazarin,
2-Hydroxy-3-ethylnaphthazarin, 2-hydroxy-3-acetylnaphthazarin, 2,7-dimethylnaphthazarin, alkanna, shikonin, acetylshikonin, isobutylshikonin, β, β'-dimethylacrylshikonin , β-hydroxyisowarelshikonin, teracrylshikonin, and derivatives thereof.

These can be used alone or in combination of two or more, and the combination is selected as appropriate.

Among these naphthoquinone-based natural pigments, particularly preferred are shikonins such as shikonin, acetylshikonin, isobutylshikonin, β, β'-dimethylacrylshikonin, β-hydroxyisowallershikonin, and teracrylshikonin, and naphthazarin, 2 .3-Dihydroxynaphthazarin, 2-methylnaphthazarin, 2-hydroxynaphthazarin, 2-hydroxy-3-methylnaphthazarin, 2-hydroxy-3-ethylnaphthazarin, 2-
These are naphthazarins such as hydroxy-3 acetylnaphthazarin and 2,7-dimethylnaphthazarin. These shikonins and naphthazarins can be obtained by extracting the roots of purple roots (purple roots) with an organic solvent.

Component (B) of the polymer scale adhesion inhibitor of the present invention is at least one component selected from the group consisting of polysaccharides and lignins.

Polymer class Ii includes starches and their derivatives such as amylose, amylopectin, dextrin, oxidized starch, acetyl starch, nitrostarch, methyl starch, and carboxymethyl starch; pectin, pectic acid, protopectin, pectinic acid, alginic acid, laminarin, Hydroxyl group-containing vegetable mucilage polysaccharides such as fucoidin and carrageenan; hydroxyl group-containing animal mucilage polysaccharides such as hyaluronic acid, chondroitin sulfate, heparin, keratosulfate, chitin, caronin sulfate, and rimakoitin sulfate; methylcellulose, ethylcellulose, and carboxylic acid; Methyl cellulose, glycol cellulose, benzyl cellulose, cyanoethyl cellulose, methylene ether of cellulose, triphenyl methyl cellulose, formyl cellulose, cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate,
Cellulose derivatives such as cellulose sulfonate ester, cellulose carbamate ester, nitrocellulose, cellulose phosphate, and cellulose xanthate; hemicelluloses such as xylan, mannan, arabogalaccum, galactan, and arapan; and the like.

Examples of lignins include alcohol lignin, dioxane lignin, phenolic lignin, hydrotropic lignin, mercaptrignin, thioglycolic acid lignin, lignin sulfonic acid, alkali lignin, thioalkali lignin, acid lignin, copper oxide-ammonia lignin, and periodic acid lignin. Examples include.

These polysaccharides and lignins can be used alone or in combination of two or more.

Among these, particularly preferred are amylose, amylopectin, oxidized starch, acetyl starch, carboxymethyl starch, pectic acid, alginic acid, chitin,
These are galactan, methylcellulose, cellulose phosphate, and carboxymethylcellulose.

The polymer scale adhesion inhibitor of the present invention includes the above (A)
, (B) In addition to both components, a solvent is included as necessary.

In addition, this polymer scale anti-adhesion agent contains various anionic, cationic, and amphoteric hydrophilic polymer compounds, surfactants, amine compounds, phenol group-containing compounds, and quinone-based compounds in order to enhance the scale prevention effect. Compounds etc. can also be added.

The polymer scale adhesion prevention agent of the present invention prevents scale adhesion to the inner wall surface of the polymerization vessel by being formed as a coating film on the inner wall surface of the polymerization vessel.

Usually, when forming the coating film on the inner wall surface of a polymerization vessel, it is used in the form of a solution, that is, as a coating liquid.

The above-mentioned coating liquid manufactured by Nobuoka Mushuku consists of the above-mentioned (A) component and (B)
Prepared by adding the ingredients to the appropriate solvent.

Examples of the solvent used for preparing such a coating solution include water; methanol, ethanol, propatool, butanol, 2-butanol, 2-methyl-1-propatool, 2-methyl-2-propatool, 3 -methyl-1-
Alcohol solvents such as butanol, 2-methyl-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. Ether solvents such as 4-methyldioxolane and ethylene glycol diethyl ether; Furans; aprotic solvents such as dimethylformamide, dimethyl sulfoxide and acetonitrile. These solvents may be used alone or as a mixed solvent of two or more.

The total concentration of components (A) and (B) in the coating liquid is not particularly limited as long as the coating amount per unit area described below can be obtained, but it is usually 0.001 to 20% by weight, preferably 0.001 to 20% by weight. It is about 0.005 to 5% by weight. In addition, (
The content ratio of component A) and component (B) is usually 0.1 to 5,000 parts by weight, preferably 1 to 1,000 parts by weight of component (B) per 100 parts by weight of component (A). If component (B) is too much or too little compared to component (A), (A)
If component (B) is used in combination, there is a possibility that the effect of preventing scale adhesion may not be obtained.

Moreover, the pH of the coating liquid is not particularly limited. If necessary, a pHII adjuster can be added. Examples of pH adjusting agents include sulfuric acid, phosphoric acid, acetic acid, oxalic acid, lactic acid, p-)luenesulfonic acid, phytic acid, thioglycolic acid, glycolic acid, sodium hydroxide, potassium hydroxide, aqueous ammonia, and ethylenediamine. listed and used as appropriate.

To form a coating film on the inner wall surface of the polymerization vessel using the coating liquid prepared as described above, first, apply the coating liquid to the inner wall surface of the polymerization vessel, and then, for example, heat from room temperature. After sufficiently drying at a temperature of up to 100°C, further washing with water is performed as necessary. In this way, since a coating film is formed on the inner wall surface of the polymerization vessel, adhesion of polymer scale to the inner wall surface of the polymerization vessel is prevented.

Further, it is preferable that the coating liquid is applied not only to the inner wall surface of the polymerization vessel but also to other parts that come into contact with the monomer during polymerization, thereby forming a coating film.

For example, it is preferable to form a coating film on stirring blades, stirring shafts, baffles, condensers, headers, search coils, bolts, nuts, etc. by applying the coating liquid. In particular, stirring blades,
Usually, a coating film should be formed on the stirring shaft and the baffle by applying the coating solution. To form a coating film by applying a coating liquid to these parts, it is possible to perform the same process as in the case of forming a coating film on the inner wall of the polymerization vessel.

More preferably, the coating liquid is applied to areas where polymer scale may adhere even to areas other than those that come into contact with monomers during polymerization, such as equipment and piping of an unreacted monomer recovery system. It is preferable to apply the coating liquid to the inner surface to form a coating film.

More specifically, such sites include the inner surfaces of monomer distillation columns, condensers, monomer storage tanks, valves, and the like. The coating film may be formed at these locations in the same manner as in the case of forming the coating film on the inner wall of the polymerization vessel.

In this way, by forming a coating film on areas that come into contact with monomers during polymerization and other areas where polymer scale may adhere, the adhesion of polymer scale to those areas is prevented. Ru.

The method of applying the coating liquid to the inner wall surface of the polymerization vessel is not particularly limited, and includes, for example, brush coating, spray coating, and a method of filling the polymerization vessel with the coating liquid and then drawing it out.
Others: JP-A-57-61001, JP-A No. 55-3628
No. 8, Special Publication No. 56-501116, No. 5650111
It is also possible to use the automatic coating method described in No. 7, JP-A-59-11303, and the like.

Further, the method of drying the surface that is wet due to the application of the coating liquid is not limited, and for example, the following method can be used.

That is, after applying the coating liquid, a method in which appropriately heated hot air is applied to the coating surface, or a method in which the inner wall surface of the polymerization vessel and other surfaces to which the coating liquid is to be applied are heated to, for example, 30 to 80°C in advance. , a method of directly applying a coating liquid to the heated surface, etc. can be used. After the coated surface is dried, the coated surface is washed with water if necessary.

The coating film thus obtained has a coating amount per unit area of usually 0.001 g/M or more, particularly 0.05 to
2g/n? It is preferable that

The above coating operation may be performed every time one to ten batches of polymerization are carried out. Since the formed coating film has high durability and the effect of preventing the adhesion of polymer scale continues, it is not necessary to carry out the process every time one batch of polymerization is carried out. Therefore, the productivity of the product polymer is improved.

After forming a coating film by coating the inner wall of the polymerization vessel and preferably other areas that will come into contact with the monomer during polymerization as described above, polymerization is carried out in the polymerization vessel by a conventional method. I do. That is, in addition to the monomer and polymerization initiator (catalyst), if necessary, a polymerization medium such as water, and a suspending agent,
A dispersant such as a solid dispersant, a nonionic emulsifier, an anionic emulsifier, etc. is charged, and then polymerization is carried out by a conventional method.

The monomer to be polymerized by applying the method of the present invention is a vinyl chloride monomer or a mixture of a vinyl chloride monomer and a monomer copolymerizable with vinyl chloride. Examples of monomers copolymerizable with vinyl chloride include vinyl esters such as vinyl acetate and vinyl propionate; acrylic acid, methacrylic acid, and esters or salts thereof; maleic acid, fumaric acid, and esters or salts thereof; Anhydrides; examples include styrene, acrylonitrile, vinylidene halides, and vinyl ethers.

Furthermore, although the type of polymerization to which the method of the present invention is applied is not particularly limited, suspension polymerization, particularly suspension polymerization of a polymerization system containing partially saponified polyvinyl alcohol and/or fully saponified polyvinyl alcohol as a dispersant, is particularly preferred. Shows effective scale prevention effect.

Hereinafter, the boat-based polymerization method will be specifically explained using suspension polymerization as an example.

First, water and a dispersant are charged into a polymerization vessel, and then a polymerization initiator is charged. Next, the inside of the polymerization vessel was evacuated and 0.1 to 7
After reducing the pressure to 60 mmHg, charge the monomer (at this time, the internal pressure of the polymerization vessel is usually 0.5 to 30 kgf/cJ-G
) and then polymerized at 30-80°C. During polymerization, one or more of water, a dispersant, and a polymerization initiator are added as necessary. Polymerization occurs when the internal pressure of the polymerization vessel drops to 0 to 7 kgf/cIlI-G, or when the difference between the inlet temperature and outlet temperature of the cooling water flowing into and out of the jacket installed around the polymerization vessel almost disappears. (i.e., when the heat generated by the polymerization reaction has disappeared),
It is considered complete. The water, dispersant, and polymerization initiator charged during polymerization are usually 20 to 500 parts by weight of water, 0.01 to 30 parts by weight of dispersant, and 0.00 parts by weight of polymerization initiator per 100 parts by weight of monomer. 01 to 5 parts by weight.
゛When polymerization is carried out by applying the polymer scale adhesion prevention method of the present invention, it is possible to prevent polymer scale adhesion regardless of the material of the inner wall surface of the polymerization vessel. The adhesion of polymer scale can also be prevented when polymerization is carried out in other steel polymerization vessels, glass-lined polymerization vessels, etc.

Those added to the polymerization system can be used without any restrictions. That is, for example, t-butylperoxyneodecanoate, bis(2-ethylhexyl)peroxydicarbonate, 3,5°5-trimethylhexanoyl peroxide, α-cumylperoxyneodecanoate, cumene hydroperoxide. , cyclohexanone peroxide, t-butyl peroxypivalate, bis(2-ethoxyethyl) peroxydicarbonate,
Benzoyl peroxide, lauroyl peroxide, 2.4-dichlorobenzoyl peroxide, diisopropyl peroxydicarbonate, α,α'-azobisisobutyronitrile, α,α'-azobis-2.4-
dimethylvaleronitrile, potassium beroxonisulfate,
Polymerization initiators such as ammonium peroxodisulfate and p-menthane hydroperoxide; partially saponified polyvinyl alcohol, completely saponified polyvinyl alcohol, polyacrylic acid, copolymer of vinyl acetate and maleic anhydride,
Suspending agents such as cellulose derivatives such as hydroxypropyl methylcellulose, natural or synthetic polymer compounds such as gelatin; Solid dispersing agents such as calcium phosphate and hydroxyapatite; Nonions such as sorbitan monolaurate, sorbitan triolate, and polyoxyethylene alkyl ether Emulsifiers; anionic emulsifiers such as sodium alkylbenzenesulfonate such as sodium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium dioctylsulfosuccinate; fillers such as calcium carbonate and titanium oxide; -basic lead sulfate, calcium stearate, dibutyltin Stabilizers such as dilaurate and dioctyltin mercaptan; lubricants such as rice wax, stearic acid, and cetyl alcohol; emollients such as DOP and DBP; mercaptans such as t-dodecyl mercaptan;
Even in a polymerization system in which a chain transfer agent such as trichlorethylene is present, the method of the present invention can effectively prevent the deposition of polymer scale.

〔Example〕

Hereinafter, the present invention will be explained in detail by giving Examples and Comparative Examples. In addition, experiment N marked with * in Table 1 below
o is a comparative example, and the other experiment numbers are examples of the present invention.

Polymerization was carried out in the following manner using a stainless steel polymerization vessel equipped with a stirrer and having an internal volume of 100 p.

In each experiment, component (A) (naphthoquinone natural pigment) and component (B) (hydroxyl group-containing polymer compound) were first dissolved in a solvent to a total concentration as shown in Table 1, and then the pH Measure p and if necessary
Each coating solution was prepared by adding an HMIJ conditioner. Next, this coating liquid is applied to the inner wall of the polymerization vessel, the stirring shaft, stirring blades, and other parts that come into contact with the monomer during polymerization.
After heating and drying at 0°C for 10 minutes to form a coating film, it was washed with water.

However, experiment No. 101 is a comparative example in which no coating liquid was applied, and experiment No. 102.103 is a comparative example in which a coating liquid containing only either component (A) or component (B) was applied. be. Also, experiment No. 108.116
is a comparative example in which azine-based synthetic dye C,1 and Acid Black 2 were used as (^) components.

Component (A) and (
B) Types of components, weight ratio (A)/(B) of components (A) and (B) in the coating solution, type of solvent used, total concentration of (A) + (B) in the coating solution , the type of pH adjuster added, and the pH of the coating solution are shown in Table 1.

Thereafter, 400 kg of water, 200 kg of vinyl chloride, 250 g of partially saponified polyvinyl alcohol, 25 g of hydroxypropyl methylcellulose, and 75 g of diisopropyl peroxydicarbonate were charged into the polymerization vessel in which the coating film was formed by the coating process, and the mixture was stirred. Nakara 5
Polymerization was carried out at 7°C for 6 hours.

After the polymerization was completed, the amount of polymer scale adhering to the inner wall of the polymerization vessel (polymer scale adhesion amount) was measured.

Moreover, the whiteness of the polymer obtained in each experiment No. was measured by the following method.

100 parts by weight of polymer, 1 part by weight of stabilizer TS-101 (manufactured by Akishima Kagaku Co., Ltd.) and 0 parts by weight of C-100J (manufactured by Katsuta Kako Co., Ltd.)
．． After kneading 5 parts by weight and 50 parts by weight of the plasticizer DOP at 160°C for 5 minutes using a two-roll mill, the mixture was formed into a sheet having a thickness of 1 mm. Next, divide this sheet into 4
A measurement sample was prepared by placing it in a mold of cmX 4 cmXl and 5 cm (thickness), and heating and press-molding it at 160° C. and 165 to 70 kg f.i.ci. For this measurement sample, the brightness index according to Hunter's color difference formula described in JIS Z8730 (1980) was determined, and it was evaluated that the larger the L value, the higher the whiteness.

The L value was determined as follows.

■ In accordance with the description of JIS Z 8722, a standard light C1 photoelectric colorimeter (Z-1001 manufactured by Nippon Denshoku Kogyo Co., Ltd.) was used.
X
The stimulus value Y of the YZ color system was determined. Condition d described in section 4.3.1 of JIS Z 8722 was adopted as the geometric conditions for illumination and light reception.

(2) Next, L was determined using the formula described in JIS Z 8730 (1980): L = 10Y''2.

Furthermore, the fish eyes when the polymers obtained in each experiment No. were molded into sheets were measured by the following method.

100 parts by weight of polymer, 50 parts by weight of DOP, 1 part by weight of dibutyltin dilaurate, 1 part by weight of cetyl alcohol, 0.25 parts by weight of titanium oxide, 0.05 parts by weight of carbon black.
After kneading the mixture prepared in the proportions of parts by weight at 150"C for 7 minutes using a 6-inch roll, the mixture was mixed to a thickness of 0.2 mm.
The number of fish eyes contained per sheet 100c111 obtained was determined by a light transmission method.

The results of each measurement are shown in Table 1.

Also, experiment No. 101, 108.116.104.
105.109.111.

Regarding the polymer obtained in 114, 119, 120,
The bulk specific gravity was measured according to the description in section 3.3 of JISK 6721 using a bulk specific gravity measuring device (manufactured by Kuramochi Scientific Instruments Manufacturing Co., Ltd.; Kasa Specific Gravity Meter). The results are shown in Table 2.

Table 2 [Effects of the Invention] According to the present invention, it is possible to always effectively prevent the deposition of polymer scale in the polymerization or copolymerization of vinyl chloride or a monomer mixture mainly composed of vinyl chloride. The coating film formed using the polymer scale adhesion inhibitor of the present invention does not peel off or dissolve in the polymerization system. Therefore, when the present invention is applied, there is no fear that the product polymer will be colored, and as a result, high whiteness with an L value of 70 or more can be obtained, and the molded product has significantly less fins eye. Moreover, a high-quality product polymer with no decrease in bulk specific gravity can be produced.

Furthermore, according to the present invention, the adhesion of polymer scale can be effectively prevented regardless of the polymerization conditions such as the type of monomer and polymerization initiator used, the polymerization type, and the material of the inner wall of the polymerization vessel. can do. In particular, in suspension polymerization, no matter which polymerization vessel is used, such as a stainless steel polymerization vessel or a glass-lined polymerization vessel, or even when a polymerization initiator with strong oxidizing power is used, the polymer scale adhesion can be more effectively prevented.

Therefore, when polymerization is carried out by applying the present invention,
It is not necessary to remove polymer scale after each polymerization, which improves productivity and allows production of high-quality product polymers.

Claims (2)

[Claims] (1) For the polymerization of a vinyl chloride monomer or a monomer mixture mainly composed of vinyl chloride, containing (A) a naphthoquinone natural pigment and (B) at least one selected from the group consisting of polysaccharides and lignins. polymer scale adhesion inhibitor. (2) A method for preventing the adhesion of polymer scale during polymerization of a vinyl chloride monomer or a monomer mixture mainly composed of vinyl chloride in a polymerization vessel, in which (A) Adhesion of polymer scale by performing the polymerization in a polymerization vessel in which a coating film containing at least one selected from the group consisting of naphthoquinone-based natural pigments and (B) polysaccharides and lignins is formed. How to prevent it.