JPS61233002A - Method for polymerizing vinyl based monomer - Google Patents

Abstract

PURPOSE:To prevent effectively the scale deposit on the inner surface of equipment, by applying a reaction product of a hydroxystyrene polymer with an oxidizing agent previously to the inner surface of the equipment in polymerizing a vinyl based monomer. CONSTITUTION:A vinyl based monomer, e.g. ethylene or acrylonitrile, is polymer ized in an aqueous medium, preferably at 30-80 deg.C temperature to give a hydroxystyrene polymer expressed by the formula (m is >2; n is 1-3), e.g. o-hydroxystyrene or 2,5-dihydroxystyrene, which is then reached with an oxidiz ing agent, e.g. chromic acid or lead tetraacetate, normally at 0-100 deg.C to afford a reaction product. The resultant reaction product is previously applied to the inner surface of a polymerizer, preferably at 0.01-10g/m<2> ratio by the spraying, rinsing methods, etc. EFFECT:The prolonged effect is obtained due to improved adhesion to metal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to an improved method for polymerizing vinyl monomers, and more specifically to a method for polymerizing vinyl monomers using an aqueous medium.
The present invention relates to a polymerization method for preventing the deposition of polymer scale on the inner surface of polymerization reaction equipment during suspension polymerization or emulsion polymerization of I/type monomers.

[Conventional technology]

When a vinyl monomer is polymerized in the presence of a dispersant or emulsifier and a polymerization initiator, the inner surface of the polymerization reactor, that is, the inner wall thereof,
Solid polymers called scale often adhere to stirring blades, baffle plates, condensers, etc.

This scale causes a decrease in heat transfer efficiency, a decrease in product yield, a decrease in quality due to the contamination of exfoliated scale into the product, a decrease in productivity due to the labor and time required for removing the scale, and This brings about many disadvantages, such as causing occupational safety and health problems.

In order to solve these problems, many methods have been proposed to prevent scale formation and its adhesion to the polymerization vessel.

For example, there are methods in which dyes, pigments, other polar organic compounds, inorganic acids and their salts, polyvalent metal salts, etc. are applied to the inner surface of the polymerization vessel or added to the aqueous medium, but these methods do not affect their effectiveness. They have various drawbacks, such as poor durability and deterioration of product properties.

As a method for improving these methods, a method has also been proposed in which a polymer compound having a functional group that prevents scale formation is coated on the inner surface of the polymerization vessel.

Conventionally, phenolic compounds (1) have been used as polymerization inhibitors, and many methods using them have been proposed.

For example, JP-A No. 55-16004 discloses a product in which a phenol aldehyde initial condensate is reacted with nitrophenols, and U.S. Pat. No. 4,080,173 discloses
Self-condensed polyhydric phenols and polyhydric naphthols, JP-A-55-54317, condensates of phenolic compounds and aromatic aldehydes, JP-A-55-102,610
In the publication, alginate propylene glycol ester,
[[No. 55-11209 discloses 2) IJ-containing polymers; JP-A No. 58-204006 discloses a reaction product of a drying oil or a semi-drying oil with a 7-Nol compound and, if necessary, an aldehyde, etc. A method of coating the inner surface of a polymerization vessel is disclosed.

[Problem that the invention seeks to solve]

However, these methods have many problems that need improvement, such as a decrease in the polymerization rate and problems with the sustainability of the descaling effect due to insufficient durability of the coating film.

As a result of intensive research aimed at solving these drawbacks, the present inventors have discovered that certain types of organic polymers are particularly effective in polymerizing vinyl monomers, and have completed the present invention.

[Means for solving problems]

That is, in the present invention, when a vinyl monomer is polymerized in an aqueous medium, a reaction product obtained by reacting an oxystyrene polymer represented by the following formula with an oxidizing agent is placed on the inside of the polymerization reactor in advance. Rather than coating, it is a method of polymerizing vinyl monomers that prevents scale adhesion on the inner surface of polymerization equipment.

The oxystyrene polymer used in the present invention is represented by the following formula and can be produced by polymerizing the oxystyrene shown below.

Oxystyrene compounds can be synthesized by various methods, but a typical example is monovalent oxystyrene.
Ohem, Ber 41, 567 (1908).

J, Ohsmloc, 51806 (1951), He
1v, Ohim.

The method described in Aata 2B, 722 (1945) and the like can be exemplified. Regarding oxystyrene with a valence of more than 2, J, Am, Ohem, So
a.

50, 2566 (1928), T. Am, Ohe.
For example, the method described in J. M., Soc 71°467 (1949) and the like can be exemplified.

The oxystyrene polymer is produced by thermally polymerizing the oxystyrene monomer or by azoisobutyronitrile.

It can be produced by a polymerization method using a radical polymerization catalyst such as benzoyl peroxide and a cationic polymerization catalyst such as aluminum trichloride or boron trifluoride.

As a representative example, 7. Am.

Ohem, Soc, 71.402 (1949), aT
, Polym.

Sci., A4.1773 (1966), J. Pol.
ym, Sci.

A7, 2175 (1969) and the like can be exemplified.

The oxystyrene polymer thus obtained has a molecular weight of 2
The number range is about 500,000 to 30,000, preferably 1,000 to 10,000, which is well used for this purpose.

Specifically, oxystyrene polymers include 1 such as 0-oxystyrene, m-oxystyrene, and p-oxystyrene.
divalent oxystyrene polymers, 2,5-dioxystyrene, 2,4-dioxystyrene and other divalent oxystyrene polymers, 3,4.5-trioxystyrene, 2,4.5-dioxystyrene
- Pentavalent oxystyrene polymers such as trioxystyrene can be mentioned.

The oxystyrene polymer thus obtained was mixed with an oxidizing agent at 0°C.
A reaction product can be obtained by reacting at a temperature of -100°C.

The oxidizing agent used in the present invention is chromic acid.

Nishiacetic acid ship, halogenic acid, primary hypohalous acid, hydrogen peroxide,
Oxidizing agents commonly used in the oxidation reaction of heptanol compounds, such as organic peroxides and nitric acid, can be used. The amount of the oxidizing agent used is 1 mol N to 1 mol of the polyhydric phenolic compound.
It can be used in a range of 10 moles.

The reaction product obtained by reacting the oxystyrene polymer thus obtained with an oxidizing agent is used after being dissolved in a hydrocarbon solvent or aqueous alkaline solution.

This solution is applied by spraying, rinsing, or the like at a ratio of α01 g/m' to 1 (1/ff/(as polymer)) per square meter of the surface of the polymerization vessel to be used.

Polymerization of vinyl monomers using the present invention includes suspension polymerization,
Emulsion polymerization is employed. The dispersant used in this polymerization,
There are no particular restrictions on the emulsifier, initiator, etc., and commonly used ones can be used.

For example, dispersants and emulsifiers include partially saponified polyvinyl acetate, acrylic acid copolymers, Cell-Tase derivatives, gelatin, starch, and other protective colloidal compounds, or higher fatty acids and polyhydric alcohols. Anionic surfactants such as esters of , polyoxyethylene derivatives, metal salts of higher fatty acids, metal salts of alkylbenzenesulfonic acids, etc. are used.

Benzoyl peroxide is used as a polymerization initiator.

Organic peroxides such as lauroyl peroxide and dioctyl peroxydicarbonate, azo compounds such as azobisisodimethylvaleronitrile, and persulfates such as potassium persulfate and ammonium persulfate are used.

The vinyl monomers mentioned here are monomers having a vinyl group, such as olefins such as ethylene and propylene, vinyl halides such as vinyl chloride and vinylidene chloride, and vinyl esters such as vinyl acetate. , vinyl ethers such as ethyl vinyl ether, acrylic ethers such as methyl methacrylate, metal salts or esters such as maleic acid and hexamaric acid, aromatic vinyls such as styrene, dienes such as butadiene, polytetraprene, isoprene, etc. Examples include monomers such as acryl tetranitrile, etc.

The polymerization temperature used is a commonly used range of 50 to 80°C.

Although the present invention can be used to polymerize the above-mentioned vinyl monomers alone or a mixture of two or more vinyl monomers, it is particularly effective in polymerizing monomers mainly composed of vinyl chloride.

〔Effect of the invention〕

The present invention can significantly prevent scale adhesion, and has excellent adhesion to metals, so a sustained effect can be obtained.

〔Example〕

The present invention will be specifically explained below using Examples.

Reference example 1 Oxystyrene 200 synthesized by thermal decomposition of fumaru
9. Tetrahuman T: 17 > 500 ILl and azobisisobutyronitrile 29 were placed in a reaction vessel No. 11, the atmosphere was replaced with nitrogen, and the mixture was reacted at 60° C. for 15 hours.

The product was diluted with methanol and precipitated with a large excess of seaweed grains, and the precipitate was washed with water and dried under reduced pressure at 50°C. The molecular weight of the obtained oxystyrene polymer was 2,000.

100g of this polymer, 7809g of pure water. Charge 339 sodium hydroxide into a Mitsuro flask, and while stirring at room temperature, 13 mol% sodium hypochlorite aqueous solution 145
dripped with water. After stirring for 5 hours, hydrochloric acid was added to neutralize and precipitate the reaction product. After dehydration, washing with water, and drying, a reaction product was obtained.

Examples 1-5 Volume 1000I! Oxystyrene heavy metals were synthesized in a stainless steel polymerization vessel according to the method shown in Reference Example IK, oxidized with sodium hypochlorite to obtain a reaction product, and a 5% acetone solution thereof was spray-coated and dried.

At this time, the coating amount was α59/nl.

Vinyl chloride 20019 was added to this polymerization vessel. Pure water 400J9° Partially saponified polyvinyl acetate 1509. Azobisisodimethylvaleronitrile 609 was added and polymerization was carried out at 57° C. for 9 hours with stirring.

After the polymerization was completed, the amount of scale attached was measured, and the results shown in Table 1 were obtained.

Examples 6 to 10 A 4% acetone solution of the oxidation reaction product of the oxystyrene polymer used in Examples 1 to 5 was spray applied to a stainless steel polymerization vessel having a capacity of 10,007 F, and dried. The coating amount was α49/n/.

This polymerization vessel contained 190 kg of vinyl chloride and 10 J of vinyl acetate.
9. 9. Pure water 450. Partially saponified polyvinyl acetate 180
g, add azobisdimethylvaleronitrile 609 to 5
Polymerization was carried out at 7° C. for 10 hours with stirring.

After the polymerization was completed, the amount of scale attached was measured, and the results shown in Table 2 were obtained.

Examples 11 to 15 A 3% acetone solution of the oxidation reaction product of the oxystyrene polymer used in Examples 1 to 5 was spray applied to a stainless steel polymerization vessel with a volume of 1000/ml and dried. The amount of application is α
It was 39/-. This polymerization vessel was Kurota Plain 200J.
19. Polyoxystyrene tallow alkylpropylene diamine 8 to 9. Acetic acid 2 to 9. Alumina sol IJc9. sodium formaldehyde sulfoxylate) 0.04Ic
9. 200~ of pure water was added, and the polymerization was completed in 10 hours while adding 21 cg of t-butyl hydroperoxide [LO] at 40°C. After the polymerization was completed, the amount of scale attached was measured, and the results shown in Table 5 were obtained.

Comparative Examples A, B, 0 126 parts by weight of pyrogallol and formaldehyde (concentration 3
5%) was added to 2,000 parts by weight of a 50% by weight phosphoric acid aqueous solution and reacted at 60°C for 1 hour to obtain a water-insoluble solid. This solid was washed with water, dried, made into a 3% acetone solution, spray-coated, and dried. The coating amount at this time was Q, 497-.

Comparative example A is Examples 1 to 5, and comparative example B is Examples 6 to 10.
In Comparative Example 0, polymerization was performed under the same conditions as Examples 11 to 15. The results are shown in the table in comparison with Examples.

In all of the examples on the base, the number of effective batches was improved by significantly reducing the amount of scale deposited and improving the durability of the coating film compared to the comparative example.

11 The effective number of batches in the table refers to the number of effective batches, because the applied scale adhesion preventive agent peels off when slurry is stirred due to polymerization, so the scale adhesion preventive effect is lost, and the quality is adversely affected by foreign matter, such as two hues. No more cleaning work, ↓

Claims (5)

[Claims] (1) When polymerizing vinyl monomers in an aqueous medium,
There are ▲mathematical formulas, chemical formulas, tables, etc. shown by the following formulas▼(m>2, n=1~
3) A method for polymerizing vinyl monomers, which comprises applying a reaction product obtained by reacting an oxystyrene polymer with an oxidizing agent to the inner surface of a polymerization device in advance. (2) The polymerization method according to claim 1, wherein the vinyl monomer is vinyl chloride alone or a mixture of vinyl chloride and a monomer copolymerizable therewith. (3) The oxystyrene polymer is o-oxystyrene,
The polymerization method according to claim 1 or 2, wherein the polymer is a monovalent oxystyrene polymer such as m-oxystyrene or p-oxystyrene. (4) The polymerization method according to claim 1 or 2, wherein the oxystyrene polymer is a divalent oxystyrene polymer such as 2,5-dioxystyrene or 2,4-dioxystyrene. (5) Claim 1 or 2, wherein the oxystyrene polymer is a polymer of three oxystyrenes such as 3,4,5-trioxystyrene and 2,4,5-trioxystyrene. polymerization method.