JPH0873510A - Method for producing vinyl chloride polymer - Google Patents

Abstract

(57) [Summary] [Structure] (a) A condensation product having a molecular weight of 400 to 50,000 obtained by condensing a quinone compound on the inner wall surface of the polymerization vessel,
And (b) at least one selected from the group consisting of water-soluble polymer compounds, inorganic colloids, and alkali metal silicates
An alkaline liquid containing seeds is applied to the inner wall surface and dried to form a scale-preventing coating film, and aqueous suspension polymerization of vinyl chloride or the like is carried out in the polymerization vessel. At that time, a specific t-butylperoxyneoheptanoate as an oil-soluble polymerization initiator and a solution state of a concentration of 0.1 mol / L in benzene were used, and the 10-hour half-life temperature was 44 to 55 ° C. Used in combination with a perester type peroxide other than t-butyl peroxy neoheptanoate. [Effect] It is possible to produce a vinyl chloride polymer having a low degree of polymerization, which is excellent in quality such as initial colorability, in a short polymerization time and while suppressing the adhesion of polymer scale in the polymerization vessel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a vinyl chloride-based polymer, and more particularly to a vinyl chloride-based polymer having a low degree of polymerization of 850 or less, which has high quality and prevents adhesion of polymer scale. The present invention also relates to a method for producing a vinyl chloride polymer, which is suitable for production.

[0002]

2. Description of the Related Art Vinyl chloride polymers are generally prepared by adding a vinyl chloride monomer or a mixture of vinyl monomers mainly containing vinyl chloride monomer in an aqueous medium to obtain an oil-soluble polymerization initiator, a dispersion stabilizer, and if necessary. It is produced by suspension polymerization using a chain transfer agent. The polymerization initiator used at this time has quality characteristics such as the heat generation pattern of the polymerization reaction, the polymerization time, the productivity, the polymer scale adhesion during the polymerization, the initial colorability of the polymer, and the thermal stability depending on the type. Have a great influence on.

In recent years, the polymerization time has been shortened for the purpose of improving the productivity of vinyl chloride polymers. As one method for shortening the polymerization time, it can be considered to increase the addition amount of the polymerization initiator. However, as the amount of the polymerization initiator added increases, there are problems that the quality of the polymer deteriorates, especially the initial colorability decreases, and the amount of polymer scale attached in the polymerization vessel increases. Especially when producing a vinyl chloride polymer with a low degree of polymerization of 850 or less, it is usually 58 ° C.
Although it is necessary to carry out the polymerization at the above temperature, conventionally used polymerization initiators, for example, di-3,5,5-trimethylhexanoyl peroxide, lauroyl peroxide, t-hexyl peroxypivalate, When t-amyl peroxypivalate or the like is used, there is a disadvantage that the quality of the polymer is lowered, especially the initial colorability is lowered, and scale is apt to adhere to the inside of the polymerization vessel.

By the way, in order to prevent adhesion of polymer scale in a polymerization vessel, dyes, pigments, water-soluble polymer compounds, nitrites, nitrogen-containing aromatic compounds, heterocyclic compounds, iodo compounds and pyrogallol have been conventionally used. Derivatives, phenolic compounds, aromatic amine compounds and the like have been applied to the inner surface of a polymerization vessel as a polymer scale adhesion preventing agent. However, in these conventional polymer scale anti-adhesion agents, the adhesion of the polymer scale in the polymerization vessel during the production of the vinyl chloride-based polymer having a low degree of polymerization, particularly the vapor phase part and the vapor phase-
Polymer scale adhesion at the liquid phase interface cannot be effectively suppressed.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art. The object of the present invention is to provide a vinyl chloride polymer having good quality such as initial colorability in a short polymerization time. Moreover, it is an object of the present invention to provide a manufacturing method capable of manufacturing while suppressing the adhesion of the polymer scale in the polymerization vessel.

[0006]

According to the present invention, in order to solve such a problem, a vinyl chloride monomer is provided in a polymerization vessel having a coating film for preventing polymer scale adhesion on the inner wall surface of the polymerization vessel. Alternatively, in a method for producing a vinyl chloride-based polymer, which comprises suspension-polymerizing a mixture of vinyl-based monomers mainly composed of the same in an aqueous medium using an oil-soluble polymerization initiator, the polymer scale adhesion prevention is performed. -Resistant coating has a molecular weight of 400-400 obtained by condensing (a) a quinone compound.
50000 condensation products, and (b) water-soluble polymer compounds,
The oil-soluble polymerization initiator is formed by applying an alkaline liquid containing at least one selected from the group consisting of inorganic colloids and alkali metal silicates to the inner wall surface and drying the same. , (A) t-butylperoxyneoheptanoate and (B) benzene in a solution state of a concentration of 0.1 mol / L, a 10-hour half-life temperature of 44 to
There is provided a method for producing a vinyl chloride-based polymer, which is characterized by comprising a component (A) having a temperature of 55 ° C. and a perester-based peroxide other than t-butylperoxyneoheptanoate.

That is, in the method for producing a vinyl chloride polymer of the present invention, suspension polymerization is carried out using a specific oil-soluble polymerization initiator in a polymerization vessel having a specific polymer scale adhesion preventive coating film. There is a new feature in the point. The details will be described below.

Polymer scale anti-adhesive coatings The scale anti-adhesive coatings used in the method of the present invention are:
Condensation product of quinone compound with a molecular weight of 400 to 50,000 on the inner wall surface
It is formed by applying and drying an alkaline liquid containing (a) and a water-soluble polymer compound (b).

The quinone compound used for preparing the condensation product (a) is, for example, a compound represented by the following general formulas (1) to (4).

Embedded image

Embedded image (In the formula, R ¹ is -H, -NH ₂ , -Cl, -Br, -OH, -NO.
_2, -COCH _3, -OCH _3, an alkyl group of -N (CH _{3) 2} or -C 1 to 3, R ² is -H, -NH _2, -OH,
-CH ₃ , -COOH or -SO ₃ H) Specifically, o-, m- and p-benzoquinone, oxy-p-benzoquinone, chloro-p-benzoquinone, bromo-p-benzoquinone, duroquinone, chloranil Etc. are illustrated.

[0010]

[Chemical 3]

[Chemical 4] (In the formula, R ¹ and R ² are as described above, and R ³ is-.
H, -Cl, -Br, -OH, -COCH 3, -OCH 3, -CH 3,
It is -COOH or -SO ₃ H) Specifically, 6-methyl-1,4-naphthoquinone, 2-methyl -
Examples include 1,4-naphthoquinone, lawson, juglone, plumbagin, α-naphthoquinone, β-naphthoquinone and the like.

Among the above quinone compounds, preferred are o- and p-benzoquinone, α-naphthoquinone, β-naphthoquinone and lawson. The quinone compound is
They may be used alone or in combination of two or more.

The condensation product (a) of the quinone compound needs to have a molecular weight in the range of 400 to 50,000, and preferably in the range of 600 to 20,000. When the molecular weight of the condensation product is less than 400, the effect of preventing polymer scale adhesion is low, and when it exceeds 50,000, the solubility of the condensation product in water and organic solvents is lowered, so that a uniform coating solution can be prepared. As a result, the resulting coating film is non-uniform, and as a result, the polymer scale adhesion preventing effect becomes low.

The condensation product (a) is produced, for example, by subjecting the above quinone compound to a condensation reaction in a suitable solvent, usually at 20 to 150 ° C. for 2 to 200 hours. At this time, in order to accelerate the condensation reaction, it is preferable to carry out the reaction in the presence of an alkaline compound. When the reaction is carried out in the presence of the alkaline compound, the quinone compound is usually added in an amount of 20 to 15
A condensation product having a desired molecular weight can be produced by reacting at 0 ° C. for 1 to 100 hours. In this case, the amount of the alkaline compound used is preferably 0.01 to 100 parts by weight, more preferably 0.1 to 10 parts by weight, based on 100 parts by weight of the quinone compound. Examples of the alkaline compound include hydroxides of alkali metals such as LiOH, NaOH and KOH.

Further, in the above condensation reaction, an oxidizing agent can be used if necessary. Examples of such oxidizing agents include elemental or molecular simple halogens such as iodine, bromine, chlorine, and fluorine; for example, oxyacids and oxygen acids of halogens such as iodic acid, periodic acid, potassium periodate, and sodium perchlorate. Salts; for example, inorganic peroxides such as hydrogen peroxide, sodium peroxide, potassium persulfate, ammonium persulfate; for example, peracetic acid, henzoyl peroxide, cumene hydroperoxide, perbenzoic acid, p
-Organic peroxides such as menthane hydroperoxide;
For example, chlorides and sulfates of metals selected from iron and copper such as ferrous chloride, ferric chloride, copper sulfate, cuprous chloride;
For example, α, α′-azobisisobutyronitrile, α,
Azo compounds such as α'-azobis-2,4-dimethylvaleronitrile; for example, nitrobenzene, o-, m- and p-oxynitrobenzene, o-, m- and p-nitroanisole, o-, m- and p. Examples thereof include aromatic nitro compounds such as -chloronitrobenzene, o-, m- and p-nitrobenzoic acid, o-, m- and p-nitrobenzenesulfonic acid.

As the solvent used for the above condensation reaction,
For example, it is preferable to use an organic solvent such as alcohols, ketones, and esters, and among them, an organic solvent miscible with water is used. Examples of the organic solvent miscible with water include alcohols such as methanol, ethanol and propanol; ketones such as acetone and methyl ethyl ketone; and esters such as methyl acetate and ethyl acetate. Alcohols are preferred. It is also possible to use a mixed solvent of the above-mentioned water-miscible organic solvent and water.

[0016] (b) a water-soluble polymer compound such as coating solution, in addition to the condensation product (a), selected from more (b) a water-soluble polymer compound, an inorganic colloid and the group consisting of alkali metal silicates At least one of As a result, the effect of preventing scale adhesion of the obtained coating film is further improved.

Water-soluble polymer compound: Examples of the water-soluble polymer compound include amphoteric polymer compounds such as gelatin and casein; anionic polymer compounds such as polyacrylic acid, polystyrene sulfonic acid, carboxymethyl cellulose and alginic acid; polyvinyl. Examples thereof include cationic nitrogen-containing polymer compounds such as pyrrolidone and polyacrylamide; hydroxyl group-containing polymer compounds such as polyvinyl alcohol, hydroxyethyl cellulose, hydroxypropyl cellulose and pectin. Among the water-soluble polymer compounds, preferred are gelatin, casein, polyacrylic acid, carboxymethyl cellulose, polyvinylpyrrolidone and pectin.

Inorganic colloid: Inorganic colloid is, for example,
It is a particle colloid produced by a dispersion method using water as a dispersion medium or an aggregation method, and the size of the colloid particles is 1 to 500 m.
is μ. Specific examples of the inorganic colloid include colloids of oxides and hydroxides of metals selected from aluminum, thorium, titanium, zirconium, antimony, tin, iron, tungstic acid, vanadium pentoxide, gold and silver. Examples thereof include colloid, silver iodide sol, selenium, sulfur, silica and the like. Preferred among these are colloids of oxides or hydroxides of metals selected from aluminum, titanium, zirconium, tin and iron, and colloidal silica.

Alkali metal silicates: Examples of alkali metal silicates include alkali metal metasilicates (M ₂ SiO ₃ ) such as lithium, sodium and potassium.
Orthosilicate (M ₄ SiO ₄ ), Disilicate (M ₂ Si ₂ O
₃ ), trisilicate (M ₃ Si ₃ O ₇ ), sesquisilicic acid (
M ₄ Si ₃ O ₁₀ ), etc. (where M is lithium, sodium,
Indicates an alkali metal such as potassium. ), As well as water glass.

Each of the water-soluble polymer compound, the inorganic colloid and the alkali metal silicate may be used alone or in combination of two or more.

These components (b) are the above condensation products.
(a) It is usually 0.01 to 10 parts by weight, preferably 0.05 to 5 parts by weight, per 1 part by weight. Preferably, the water-soluble polymer compound is used in combination with at least one of the inorganic colloid and the alkali metal vinyl silicate.
That is, it is preferable to use at least a combination of a water-soluble polymer compound and an inorganic colloid, or a combination of a water-soluble polymer compound and an alkali metal silicate.

When the water-soluble polymer compound and the inorganic colloid are used in combination, it is preferable to use 5 to 3000 parts by weight of the inorganic colloid per 100 parts by weight of the water-soluble polymer compound, and further 50 to 1000 parts by weight. Partial use is preferred.
When used in combination with a water-soluble polymer compound and an alkali metal silicate, it is preferable to use 5 to 3000 parts by weight of an alkali metal silicate per 100 parts by weight of the water-soluble polymer compound. It is preferable to use 50 to 1000 parts by weight.

Coating Solution The coating solution used for forming the polymer scale anti-adhesion coating film is prepared by adding the following solvent to the solution containing the condensation product obtained as a result of the above condensation reaction, if necessary, and adjusting the pH. If is not alkaline, it is prepared by adjusting to alkaline. In addition, the coating liquid is, for example, after the condensation product-containing liquid is poured into cold water to precipitate the condensation product, the precipitate is filtered off, and the dried product is added with the following solvent, followed by It may be prepared by adjusting the pH to be alkaline.

By making the coating solution alkaline,
The solubility of the condensation product (a) in a solvent is improved. Therefore, since the coating solution becomes a uniform solution, the coating film obtained is also uniform, and the polymer scale adhesion preventing effect is improved.

The pH of the coating solution is preferably in the range of 7.5 to 13.5, and particularly preferably in the range of pH 8.0 to 13.5. Examples of the alkaline compound used for pH adjustment include LiOH, NaOH, KO
Examples thereof include alkali metal compounds such as H, Na ₂ CO ₃ , Na ₂ HPO ₄ , and NH ₄ OH and ammonia compounds, for example, organic amine compounds such as ethylenediamine, monoethanolamine, diethanolamine and triethanolamine.

Examples of the solvent used for preparing the polymer scale anti-adhesion agent of the present invention include water; methanol, ethanol, propanol, butanol, 2-butanol, 2-methyl-1-propanol, 2-methyl-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, ethyl acetate and methyl acetoacetate; 4- Examples include ether solvents such as methyldioxolane and ethylene glycol diethyl ether; furans; aprotic solvents such as dimethylformamide, dimethylsulfoxide, and acetonitrile. These solvents are appropriately used alone or as a mixed solvent of two or more kinds.

Among the above-mentioned solvents, preferred are water and a mixed solvent of water and an organic solvent miscible with water.
Examples of the organic solvent which is miscible with water among the above organic solvents include alcohol solvents such as methanol, ethanol and propanol; ketone solvents such as acetone and methyl ethyl ketone; ester solvents such as methyl acetate and ethyl acetate. Is mentioned. When using a mixed solvent of water and a water-miscible organic solvent, the content of the organic solvent shall be such that there is no danger of ignition, explosion, etc. and there is no safety problem in handling such as toxicity. Is preferred, and specifically, the organic solvent is preferably 50% by weight or less, and further 3
It is preferably 0% by weight or less.

The concentration of the condensation product in the alkaline solution is not particularly limited as long as the total coating amount described below can be obtained, but is usually about 0.001 to 5% by weight, preferably 0.1.
It is about 0 to 1% by weight.

Formation of coating film The coating solution obtained as described above is applied to at least the inner wall surface of the polymerization vessel and dried to form a coating film. Drying is sufficiently carried out, for example, in a temperature range from room temperature to 100 ° C., and further, if necessary, washing with water. The coating film thus formed effectively prevents the scale from adhering.

The polymer scale anti-adhesion coating film is preferably formed not only on the inner wall surface of the polymerization vessel, but also on other portions where the monomer contacts during the polymerization. For example, a stirring blade, a stirring shaft, a baffle, a condenser, a header, a search coil, a bolt, a nut and the like can be mentioned.

The method of applying the coating liquid to the inner wall surface of the polymerization vessel is not particularly limited, and examples thereof include brush coating, spray coating, and a method of withdrawing after filling the polymerization vessel with the polymer scale adhesion preventive agent. , And others, JP-A-57-6
It is also possible to use the automatic coating methods described in JP-A Nos. 1001 and 55-36288, JP-A-56-501116, JP-A-56-501117, JP-A-59-11303 and the like.

The method of drying the wet surface after applying the coating solution is not limited, and the following method can be used, for example. That is, after applying the polymer scale anti-adhesive agent, a method of applying an appropriately heated hot air to the application surface, or the inner wall surface of the polymerization vessel and the other surface to which the polymer scale anti-adhesive agent is applied are preliminarily set to, for example, 30
It is possible to use a method in which the polymer scale adhesion preventing agent is directly applied to the heated surface by heating to -80 ° C. After drying the coated surface, the coated surface is washed with water as needed.

The coating film thus obtained has a total coating amount after drying of usually 0.001 to 5 g / m ² , especially
It is preferably 0.05 to ² g / m ² . The above coating operation may be performed for each batch of 1 to 10 or more batches. Since the formed coating film has high durability and the action of preventing the polymer scale from adhering continues, it is not always necessary to perform it for each batch of polymerization, so that the productivity is improved.

Polymerization Initiator In the oil-soluble polymerization initiator used in the method of the present invention, t-butylperoxyneoheptanoate is used as one of the initiators (A). The other initiator of the oil-soluble polymerization initiator
(B) has a 10-hour half-life temperature (hereinafter simply referred to as 10-hour half-life temperature) in a benzene solution having a concentration of 0.1 mol / L.
It is a perester type peroxide other than the above t-butylperoxyneoheptanoate (A) having a temperature range of 44 to 55 ° C, preferably 44 to 50 ° C. When the 10-hour half-life temperature of this initiator (B) is less than 44 ° C, in the polymerization of a low polymerization degree vinyl chloride monomer which is usually carried out at a polymerization temperature of 58 ° C or higher,
The amount of heat generated at the beginning of the polymerization becomes large, making it difficult to properly remove heat from the polymerization vessel. Further, if the one having a 10-hour half-life temperature of more than 55 ° C. is used, it is not economical because it is necessary to add a large amount of a polymerization initiator, and the initial coloring property of the obtained vinyl chloride polymer is apt to be lowered. In some cases, the quality of the polymer obtained may deteriorate.

Specific examples of such an initiator (B) include:
t-hexyl peroxy neodecanoate (10-hour half-life half-life temperature: 44.7 ° C, 10-hour half-life temperature is also shown in parentheses below), t-butylperoxy neodecanoate (46.5 ° C), Examples thereof include t-hexyl peroxy neohexanoate (49.7 ° C.) and t-butyl peroxy neohexanoate (52.1 ° C.). Among these, especially t-butyl peroxy neodecanoate, t-
Hexyl peroxy neohexanoate, t-hexyl peroxy neodecanoate and t-butyl peroxy neohexanoate are preferably used, and particularly t-butyl peroxy neodecanoate is preferably used. These may be used alone or in combination of two or more.

It is known that the 10-hour half-life temperature of an initiator composed of an organic peroxide is generally determined as follows. A benzene solution having a peroxide concentration of 0.1 mol / L is placed in a sealed container, kept at a certain temperature for thermal decomposition, and the change in the peroxide concentration with time is measured. Since this decomposition reaction can be approximately regarded as a first-order reaction, the following relationship holds. dx / dt = k (ax) ln [a / (ax)] = kt (In the formula, x: concentration of peroxide, a: initial concentration of peroxide, k: decomposition rate constant, t : Time) Since the half-life t _1/2 is the time when x = a / 2 in the formula, the following relational expression: kt _1/2 = ln2 is established. With the change in the concentration of peroxide measured above,
Since the constant k is obtained from the equation, the half-life t _1/2 is obtained from the equation.

The mixing ratio of the initiator (A) and the initiator (B) is preferably (A) / (B) = 1/9 to 9/1 by weight ratio, and particularly 1 /
It is preferably in the range of 5 to 5/1. (A) / (B) <
When it is 1/9, the initial colorability is deteriorated and the amount of scale adhesion is increased. Further, since the heat generation is excessive and becomes excessive in the initial stage of the polymerization where the conversion rate of the polymerization is 3 to 30%, the heat removal ability of the polymerization apparatus becomes insufficient, and it may be difficult to keep the polymerization temperature constant. It becomes difficult to obtain a PVC having a polymerization degree. On the other hand, when (A) / (B)> 9/1, the initial colorability deteriorates and the amount of scale adhesion increases. Also peroxide
The total amount of (A) and peroxide (B) added is 10 total amount of charged monomers.
Normally, 0.02 to 0.12 parts by weight is preferable with respect to 0 parts by weight,
Further, the range of 0.04 to 0.1 part by weight, particularly 0.05 to 0.1 part by weight is preferable. If this amount is too large, the exothermic weight at the initial stage of polymerization will be large, and it will be difficult to appropriately remove heat from the polymerization vessel, and the initial colorability of the resulting polymer may be deteriorated. The quality of the obtained polymer is also unfavorable. If this amount is too small, it is difficult to shorten the polymerization time.

The method of charging the polymerization initiator into the polymerization vessel is not particularly limited, and any conventionally known method can be used. For example, it may be diluted with a solvent and charged as a solution, or dispersed in water. Alternatively, it may be prepared as an emulsion or a suspension. Further, the polymerization initiator may be charged together with water and / or the suspending agent, or may be charged after the water and / or the suspending agent have been charged, or the monomer may be charged into the polymerization vessel with a pump.

Polymerization Other conditions in the method for producing the vinyl chloride polymer of the present invention (for example, a method for charging an aqueous medium, a monomer, a dispersion aid, etc. to a polymerization vessel, a charging ratio, etc.) are usually an aqueous medium. It may be the same as the suspension polymerization of vinyl chloride and the like.

The polymerization is usually carried out at 40 to 70 ° C., and is not particularly limited as long as it is within this temperature range. Average degree of polymerization 8
When producing a vinyl chloride-based copolymer having a low degree of polymerization of 50 or less, the polymerization is preferably carried out at 58 ° C. or higher, more preferably 59 to 68 ° C.

As the monomer, in addition to vinyl chloride alone, a mixture containing vinyl chloride as a main component and another monomer copolymerizable therewith (usually 50% by weight or more of vinyl chloride) may be used. It is possible (hereinafter, vinyl chloride or a monomer mixture containing vinyl chloride is referred to as a vinyl chloride-based monomer). As the monomer copolymerizable with vinyl chloride, ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1
-Heptene, 1-octene, 1-nonene, 1-decene,
1-undecene, 1-dodecene, 1-tridecene, 1-
Α-Olefin such as tetradecene; acrylic acid such as acrylic acid, methyl acrylate, ethyl acrylate or its ester; methacrylic acid such as methacrylic acid, methyl methacrylate or its ester; maleic acid or its ester; vinyl acetate, propionic acid Examples thereof include vinyl esters such as vinyl; vinyl ethers such as lauryl vinyl ether and isobutyl vinyl ether; maleic anhydride; acrylonitrile; styrene; vinylidene chloride; and other monomers copolymerizable with vinyl chloride. These are used alone or in combination of two or more.

The dispersant may be any of those usually used for suspension polymerization of vinyl chloride monomers in an aqueous medium. Examples of the dispersant include water-soluble cellulose ethers such as methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose and hydroxypropyl methyl cellulose; water-soluble or oil-soluble partially saponified polyvinyl alcohols; acrylic acid polymers; Molecule; sorbitan monolaurate,
Examples thereof include oil-soluble emulsifiers such as sorbitan trioleate, glycerin tristearate and ethylene oxide propylene oxide block copolymers; water-soluble emulsifiers such as polyoxyethylene sorbitan monolaurate, polyoxyethylene glycerin oleate and sodium laurate. These are used alone or in combination of two or more.

Deionized water is usually used as the aqueous medium. Further, in this polymerization system, if necessary, a polymerization regulator, a chain transfer agent, and a pH that are appropriately used for vinyl chloride-based polymerization.
Regulator, gelation improver, antistatic agent, crosslinking agent, stabilizer,
Addition of fillers, antioxidants, buffers, scale inhibitors, etc. is also optional.

[0044]

EXAMPLES Hereinafter, the present invention will be specifically described by showing Examples and Comparative Examples, but the present invention is not limited to the following Examples.

Example 1 First, the polymer scale adhesion preventive agent (I) of the present invention was produced as follows. To a reactor having an internal volume of 2 L equipped with a reflux condenser, a mixed solvent of methanol (450 g) and water (450 g) was added, and then α-naphthoquinone as a quinone compound 1
00 g and 10 g of sodium hydroxide were added. Next, the temperature in the reactor is raised to 65 ° C., and the mixture in the reactor is heated to 65 ° C.
After reacting for 10 hours, it was cooled to room temperature. Thus, a solution of the condensation product (a) was obtained.

The condensation product (a) obtained above had a molecular weight of 3000 as measured by the following method. -Measurement of molecular weight It was measured by gel permeation chromatography (GPC). The molecular weight is represented by polystyrene equivalent number average molecular weight. The measurement conditions are shown below. Column: Guard column Product name slim-pack GPC-800DP, Shimadzu analytical column Product name slim-pack GPC-803D, 802D, Shimadzu mobile phase: 10mM LiBr / DMF Flow rate: 1.0 mL / min Detector: RI temperature 60 ° C Condensation product (a) obtained above, gelatin (b), 5 to 7
mμ Snowtex CXS-9 (c) and water / methanol = 7/3 (weight ratio) as a solvent, (a) / (b) / (c)
= 1/1/1 (weight ratio), and prepared so that the total concentration of (a) + (b) + (c) would be 0.5%, and the solution was adjusted with NaOH.
The polymer scale adhesion inhibitor (I) was prepared by adjusting the pH to 11.0.

Polymer scale anti-adhesion agent (I) prepared as described above in a stainless steel polymerization vessel having an internal volume of 2.1 m ^3.
Was applied to the inner wall of the polymerization vessel, the stirring shaft, the stirring blade and other portions where the monomer comes into contact during the polymerization, and dried by heating at 40 ° C. for 15 minutes to form a coating film, and then the inside of the polymerization vessel was washed with water.

Next, an aqueous solution of 880 kg of deionized water, 210 g of partially saponified polyvinyl alcohol and 140 g of hydroxypropylmethyl cellulose was charged into the polymerization vessel. 50 inside
After deaeration to mmHg, 700 kg of a vinyl chloride monomer was charged, and while stirring, the polymerization initiator shown in Table 1 was further injected with a pump, and at the same time the temperature was started to start the polymerization.

The polymerization reaction was carried out while maintaining the polymerization temperature at 63 ° C., the polymerization was stopped when the internal pressure of the polymerization vessel dropped to 7.5 kg / cm ² G, and the unreacted monomer was recovered and The combined product was taken out of the container in a slurry form, dehydrated and dried to obtain a polymer.

Comparative Example 1 As a polymer scale adhesion inhibitor (II) of Comparative Example, CI was used.
Direct Blue 1 (10g), CI Basic Blue 12
(2 g) was dissolved in 2000 mL of ion-exchanged water, and 17 g of phytic acid was further added to prepare an aqueous solution to obtain a polymer scale adhesion inhibitor (II). This polymer scale anti-adhesion agent (II) was applied to the inside of the polymerization vessel in the same manner as in Example 1, and the mixture was heated at 50 ° C.
After heating and drying for a minute to form a coating film, the inside of the polymerization vessel was washed with water. Next, except that the polymerization initiators shown in Table 1 were used,
The vinyl chloride monomer was polymerized in the same manner as in Example 1 to obtain a polymer.

Comparative Example 2 Polymerization was carried out in the same manner as in Comparative Example 1 except that the polymerization initiators shown in Table 1 were used.

Comparative Example 3 Polymerization was carried out in the same manner as in Comparative Example 1 except that the scale inhibitors shown in Table 2 were used.

Comparative Example 4 Polymerization was carried out in the same manner as in Example 1 except that the polymerization initiators shown in Table 2 were used.

Comparative Example 5 Polymerization was carried out in the same manner as in Example 1 except that the polymerization initiator in Example 1 was changed to that shown in Table 2 to obtain a polymer. In addition, the heat removal capacity of the polymerization apparatus was insufficient for the amount of heat of polymerization reaction generated during the polymerization, and the polymerization temperature could not be maintained at 63 ° C., so that the internal temperature temporarily increased by about 3 ° C.

Example 2 In the same manner as in Example 1, a coating film of the polymer scale adhesion inhibitor (I) was formed in the polymerization vessel, and the inside of the polymerization vessel was washed with water.
870 kg deionized water and partially saponified polyvinyl alcohol 3
An aqueous solution of 03 g and 240 g of hydroxypropylmethyl cellulose was charged into the polymerization vessel. After degassing the inside of the vessel to 50 mmHg, 730 kg of vinyl chloride monomer was charged and the polymerization initiator shown in Table 3 was injected with a pump while stirring, and at the same time the temperature was started to initiate the polymerization. After 1 hour from the start of the temperature rise, 204 g of 2-mercaptoethanol as a polymerization degree adjusting agent was injected under pressure. The polymerization reaction is carried out while maintaining the polymerization temperature at 62 ° C, the polymerization is stopped when the internal pressure of the polymerization vessel reaches 7.2 kg / cm ² G, the unreacted monomer is recovered, and the obtained polymer is slurried. The product was taken out of the vessel in the form of a sheet, dehydrated and dried to obtain a polymer.

Example 3 Polymerization was carried out in the same manner as in Example 2 except that the polymerization initiator shown in Table 3 was used.

Comparative Example 6 A polymer scale adhesion inhibitor (II) was used in place of the polymer scale adhesion inhibitor (I) in Example 2, and a coating film was formed in the polymerization vessel in the same manner as in Comparative Example 1. After forming, the inside of the vessel was washed with water, and the polymerization initiator was changed as shown in Table 3 except that
Polymerization was performed in the same manner as in Example 2 to obtain a polymer.

Comparative Example 7 In Example 2, except that the coating film was formed in the polymerization vessel in the same manner as in Comparative Example 1 and then the inside of the vessel was washed with water, and the polymerization initiator was as shown in Table 4. Polymerization was performed in the same manner as in 2 to obtain a polymer.

Comparative Example 8 A polymer scale anti-adhesion agent (II) was used in place of the polymer scale anti-adhesion agent (I) in Example 2, and a coating film was formed in the polymerization vessel in the same manner as in Comparative Example 1. After the formation, the inside of the vessel was washed with water, and the polymerization initiator was changed as shown in Table 4, except that
Polymerization was performed in the same manner as in Example 2 to obtain a polymer.

The quality of each polymer thus obtained was evaluated by the following method. The results are shown in Tables 1 to 4. -Average degree of polymerization: measured according to JIS K-6721. Bulk specific gravity: measured according to JIS K-6721. -Particle size distribution: In accordance with JIS Z-8801, each of sieves # 60, # 100 and # 200 was used for sieving, and the residual amount and the passing amount (% by weight) were measured.・ Initial colorability: 100 parts by weight of the obtained polymer was mixed with 1 part by weight of tin lauryl acid, 0.5 part by weight of a cadmium stabilizer and 50 parts by weight of dioctyl phthalate, and the mixture was mixed with a two-roll mill at 160 ° C. for 5 minutes. After kneading, it was formed into a sheet having a thickness of 0.8 mm. Next, cut and stack this sheet,
Put in a 4cm × 4cm × 1.5cm mold, 160 ℃, 65-70kgf /
A sample was prepared by heating and pressing at cm ² . The sample sheet was visually observed to evaluate the initial colorability according to the following criteria. A: It has a light yellow color and is good. B: Strong yellowish color and defective. -Polymer scale adhesion: After repeating 10 batches of polymerization by each production method, the inside of each polymerization vessel was observed to evaluate the degree of adhesion of polymer scale. The abbreviations of the polymerization initiators in the table are shown below. BPNp: t-butylperoxyneoheptanoate (10-hour half-life temperature: 50 ° C.) BPD: t-butylperoxyneodecanoate (same: 46.
5 ° C) HPV: t-hexyl peroxypivalate (the same: 53.2
℃) THP: di-3,5,5-trimethylhexanoyl peroxide (the same: 59.5 ℃)

[0061]

[Table 1]

[0062]

[Table 2]

[0063]

[Table 3]

[0064]

[Table 4]

From Tables 1 to 4, the vinyl chloride polymers having a relatively low degree of polymerization obtained by the method of the present invention have good bulk density, particle size distribution and initial colorability even if the polymerization time is shortened. Met. It was also found that this production method suppresses the adhesion of polymer scale in the gas phase part and the liquid phase part in the polymerization vessel.

[0066]

According to the production method of the present invention, a vinyl chloride polymer having a low degree of polymerization and having good quality such as initial colorability can be attached in a short polymerization time and on a polymer scale in a polymerization vessel. It is possible to manufacture while suppressing. Therefore,
Productivity is significantly improved. In particular, the adhesion of polymer scale in the gas phase and near the interface in the polymerization vessel, which was difficult in the past, is more reliably suppressed, and the frequency of polymer scale removal work in the polymerization vessel is drastically reduced. It is possible to continuously use the same.

Claims (3)

[Claims] 1. A vinyl chloride monomer or a mixture of vinyl-based monomers mainly composed of the vinyl chloride monomer is oil-soluble in an aqueous medium in a polymerization vessel having a coating film for preventing polymer scale adhesion on the inner wall surface of the polymerization vessel. In the method for producing a vinyl chloride polymer, which comprises suspension polymerization using a polymerization initiator, the polymer scale adhesion preventive coating film (a) has a molecular weight of 400 obtained by condensing a quinone compound. ~ 5000
Applying an alkaline liquid containing the condensation product of No. 0 and (b) at least one selected from the group consisting of water-soluble polymer compounds, inorganic colloids and alkali metal silicates to the inner wall surface and drying. And the oil-soluble polymerization initiator is (A) t-butylperoxyneoheptanoate and (B) benzene in a solution having a concentration of 0.1 mol / L for 10 hours. A process for producing a vinyl chloride polymer, which comprises a perester-based peroxide other than the component (A) t-butylperoxyneoheptanoate having an initial temperature of 44 to 55 ° C. 2. The production method according to claim 1, wherein the suspension polymerization is performed at a temperature of 58 ° C. or higher. 3. The production method according to claim 1, wherein the component (B) described in claim 1 is t-hexylperoxy neodecanoate, t-butylperoxy neodecanoate, A method which is t-hexyl peroxy neohexanoate or t-butyl peroxy neohexanoate.