JPS62277404A - Polymerization of vinyl monomer - Google Patents

Abstract

PURPOSE:To remarkably prevent the deposition of polymer scale on the inner wall of a polymerizer in the polymerization on a vinyl monomer in an aqueous medium and to improve the durability of coating layer of the polymerizer, by coating the inner wall of a polymerizer with a specific organic polymer prior to polymerization. CONSTITUTION:A vinyl monomer such as vinyl chloride or its mixture with other copolymerizable monomer is polymerized in an aqueous medium. In the above process, the inner wall of a polymerizer is coated with a reaction product of (A) a polymeic alcohol having hydroxyl group in the molecule (e.g. polyvinyl alsohol produced by saponifying polyvinyl acetate) with (B) a phenolic compound (e.g. pyrogallol, hydroxyhydroquinone, etc.) and, if necessary, an aldehyde compound (e.g. HCHO, benzaldehyde, etc.) prior to polymerization. The above reaction product can be produced usually by reacting the components in the presence of a Friedal-Crafts catalyst in nitrogen atmosphere at 100-200 deg.C for 1-7hr.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Industrial Field of Application] The present invention relates to an improved method for polymerizing vinyl monomers, and more specifically, the present invention relates to an improved 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 a polymerization reactor during suspension polymerization or emulsion polymerization of monomers.

[Prior Art] When a vinyl monomer is polymerized in the presence of a dispersant or emulsifier and a polymerization initiator, the inner surface of a 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.

Phenolic compounds have conventionally been used as polymerization inhibitors, and many methods using them have been proposed.

For example, JP-A-55-160004 discloses a product in which a phenol/aldehyde initial condensate is reacted with nitrophenols, and U.S. Pat. No. 4,080,173 describes a self-condensed polyhydric phenol and Naphthol, JP-A-55-54317, is a condensate of phenolic compound and aromatic aldehyde, JP-A-55-1028
No. 10 discloses alginate propylene glycol ester, JP-A-54-LCI889 discloses a nitrile-containing polymer, and JP-A-58-204006 discloses a drying oil or a semi-drying oil, a phenol compound and, if necessary, an aldehyde. A method is disclosed in which a reaction product, etc., is applied to the inner surface of a polymerization vessel.

[Problems to be solved by the invention] However, when these methods are used, for example, the polymerization rate decreases, and the durability of the scale adhesion prevention effect is questionable due to insufficient durability of the coating film. There are many points.

The inventors of the present invention have carried out intensive research to solve these drawbacks, and have found that when various organic polymers, especially vinyl monomers, are coated on the inside surface of a polymerization vessel and polymerized, scale increases. The present invention was completed after discovering that adhesion can be significantly prevented and the adhesion to metals is extremely excellent.

[Means for Solving the Problems] That is, the present invention involves polymerizing a vinyl monomer in an aqueous medium by combining a polymeric alcohol having a hydroxyl group in the molecule, a phenolic compound, and optionally an aldehyde. The present invention relates to a method for polymerizing vinyl-based monomers in which scale adhesion on the inner surface of the polymerization vessel is prevented by applying a reaction product with a compound to the inner surface of the polymerization vessel in advance.

Polymeric alcohols having hydroxyl groups in the molecule used in the present invention include polyvinyl alcohol (hereinafter abbreviated as PVA) obtained by completely or partially saponifying the acetate groups of polyvinyl acetate, ethylene, vinyl chloride, and vinyl acetate. saponified copolymers of polyhydric alcohols, polymers of acrylic acid esters of polyhydric alcohols, polyglycerin and cellulose and their derivatives, or polymers with epoxy groups in their molecules such as novolac-type epoxy resins or epoxy-modified liquid polybutadiene. Examples include compounds obtained by ring-opening the epoxy group of a molecular compound.

The phenolic compound is an aromatic compound having one or more phenolic 10i+ groups.

For example, monohydric phenols such as phenol and cresol;
resorcinol, catechol, hydroquinone.

Dihydric phenols such as bisphenol A, pyrogallol,
Examples include trihydric phenols such as hydroxyhydroquinone, and compounds having a substituent such as an alkyl group and a dicarboxylic acid group on the above-mentioned compounds.

Examples of the aldehyde compound include aliphatic aldehydes such as formaldehyde, paraformaldehyde, and acetaldehyde, and aromatic aldehydes such as benzaldehyde.

The method for producing the reaction product of a polymeric alcohol having a hydroxyl group in the molecule and a phenolic compound according to the present invention includes a method for producing a reaction product between a polymeric alcohol having a hydroxyl group in the molecule and a phenolic compound using a Friedel-Crafts type catalyst or a phenolic compound. 50-250°C under nitrogen atmosphere with acid catalyst, preferably 100-2
It is produced by reacting at 00°C for 5 minutes to 10 hours, preferably 1 to 7 hours. In addition, an aldehyde compound may be added and reacted as desired, but the method of adding an aldehyde compound and reacting at this time is as follows: (1)
A method of simultaneously reacting a polymeric alcohol with a hydroxyl group in the molecule with a phenolic compound and an aldehyde compound; (2) A method of reacting a polymeric alcohol with a hydroxyl group in the molecule with a phenolic compound, and then reacting it with an aldehyde compound. There is a method in which a compound is added and reacted, and (3) a method in which a phenolic compound and an aldehyde compound are reacted, and then a polymeric alcohol having a hydroxyl group in the molecule is reacted. The reaction can also be carried out by dissolving it in an inert solvent.

Friedel-Crafts type catalysts or acid catalysts include commonly used halides such as aluminum chloride, boron butoxide, zinc chloride, iron chloride, complex compounds thereof, inorganic acids such as hydrochloric acid and sulfuric acid, and para-toluenesulfonic acid. Organic acids such as can be used.

The polymeric alcohol having a hydroxyl group in the molecule and the phenolic compound should be used in an amount of 2 to 200 parts by weight, preferably 15 to 150 parts by weight, per 100 parts by weight of the phenolic compound. used. The aldehyde compound is preferably used in an amount of 0 to 2 moles per mole of the phenolic compound, preferably 0.5 to 1.5 moles.

If the amount of the polymeric alcohol having a hydroxyl group in the molecule relative to the phenolic compound is less than the above range, the reaction rate of the phenolic compound will decrease, which is economically disadvantageous. or,
On the other hand, if the amount is too large, the effect of preventing scale adhesion of the product will be reduced.

The use of an aldehyde compound increases the effect of preventing scale adhesion, but if the amount exceeds the above range, the solubility in a solvent or alkaline solution decreases.

Catalyst (0.0% per 100 parts by weight of bephenolic compound)
01 to 30 parts by weight, preferably 0.1 to 20 parts by weight. When the amount of the catalyst is less than the above range, the reactivity decreases, while when it increases, the solubility in a solvent or alkaline solution decreases.

The scale adhesion inhibitor obtained by the reaction in this manner is used after being dissolved in a hydrocarbon polar solvent or an alkaline solution. This solution was applied as a scale adhesion prevention agent to the surface of the target polymerization vessel at a rate of 0.01 g/rr?
It is applied by spraying, rinsing, etc. at a ratio of ~log/rri'.

The appropriate concentration of the solution is 1 to 10 parts by weight; if it is thinner than 1% by weight, the effect of preventing scale adhesion cannot be obtained;
If the amount exceeds 50%, it becomes difficult to apply by spraying or rinsing.

Polymerization of the vinyl monomer used in 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.

Examples of dispersants and emulsifiers include partially saponified polyvinyl acetate, acrylic acid copolymers, cellulose derivatives,
Anionic interfaces such as protective colloidal compounds such as gelatin and starch, esters of higher fatty acids and polyhydric alcohols, anionic surfactants such as polyoxyethylene derivatives, metal salts of higher fatty acids, and metal salts of alkylbenzenesulfonic acids. An activator or the like is used.

Benzoyl peroxide is used as a polymerization initiator.

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 esters such as methyl methacrylate, metal salts or esters such as maleic acid and fumaric acid, aromatic vinyls such as styrene, diene single-heads such as butadiene, chloroprene, isoprene, etc. Examples include acrylonitrile, acrylonitrile, etc.

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

[Example 7] The present invention will be specifically explained using Examples below, but the scope of the present invention is not limited thereby. Note that parts and percentages described below are in weight units.

(Synthesis Example 1) In a 1 liter 4 flask equipped with a stirrer, a thermometer and a condenser, 20
P whose viscosity in 4% aqueous solution at °C is 4-6 Cps
70 parts of VA, 100 parts of pyrogallol, and 12 parts by weight of p-toluenesulfonic acid were charged, and a reaction was carried out at 190° C. for 5 hours under a nitrogen atmosphere. After the reaction was completed, the reaction product was washed with pure water cooled to about 0°C.

After washing, dehydration, and drying, a blackish brown reaction product soluble in methanol, acetone, and alkali was obtained.

(Synthesis Example 2) A reaction product was obtained in the same manner as in Synthesis Example 1 except that hydroxyhydroquinone was used instead of pyrogallol.

(Synthesis Example 3) A reaction product was obtained in the same manner as in Synthesis Example 1 except that resorcinol was used instead of pyrogallol.

(Synthesis Example 4) Instead of PVA used in Synthesis Example 1, PVA with a saponification degree of 3
0 to 40 mol%, methanol/water (methanol/water-
A reaction product was obtained in the same manner except that PVA whose solution had a viscosity of 9 to 13 cps at 20° C. when dissolved 10% in a mixed solvent (1/1 weight ratio) was used.

(Synthesis Example 5) In the same manner as Synthesis Example 1, 70 parts of PVA used in Synthesis Example 1, 100 parts of pyrogallol, and 12 parts by weight of p-toluenesulfonic acid were placed in a 1 liter 4-ton flask equipped with a stirrer, thermometer, and condenser. and heated to 190℃ under nitrogen atmosphere.
After reacting for 3 hours, the mixture was cooled, 50 parts of 35% formaldehyde was added, and the reaction was further carried out under reflux for 2 hours. The reaction temperature was controlled by refluxing the water in the system. Then, a reaction product was obtained in the same manner as in Synthesis Example 1.

(Synthesis Example 6) In the same manner as in Synthesis Example 1, 1 liter of pyrogallol was added to a 1 liter 4-bottle flask equipped with a stirrer, thermometer and condenser.
00 parts, 35% concentration formaldehyde 50 parts, 50%
Pour 2000 parts of phosphoric acid and react at 60°C for 1 hour.
A reddish-purple precipitate was obtained.

100 parts of the precipitate obtained by dehydrating and drying this, 70 parts of PVA used in Synthesis Example 1, and 12 parts by weight of p-toluenesulfonic acid were charged into the same flask, and heated at 190°C under a nitrogen atmosphere for 50 minutes.
After carrying out the reaction for a period of time, a reaction product was obtained in the same manner as in Synthesis Example 1.

(Synthesis Example 7) Similarly to Synthesis Example 1, 70 parts of PVA used in Synthesis Example 1, 100 parts of pyrogallol, 50 parts of 35% formaldehyde, 6 parts of oxalic acid dihydrate was charged, and the reaction was carried out for 5 hours under a nitrogen atmosphere. The reaction temperature was controlled by refluxing the water in the system. After the reaction was completed, a reaction product was obtained in the same manner as in Synthesis Example 1.

(Synthesis Example 8) In the same manner as in Synthesis Example 1, 1 liter of pyrogallol was added to a 1 liter 4-bottle flask equipped with a stirrer, thermometer and condenser.
An aqueous solution containing 26 parts and 85 parts of 35% formaldehyde was added to 2000 parts of a 50 wt% aqueous solution of phosphoric acid.
The reaction was carried out at 0°C for 1 hour to obtain a water-insoluble solid.

(Comparative Example 1) 200 ml of vinyl chloride was placed in a stainless steel polymerization vessel with an internal volume of 1.
kg, pure water 400 kg, partially saponified polyvinyl acetate 15
0 kg and 60 g of azobisdimethylvaleronitrile were 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.

(Comparative Example 2) The product obtained by the method of Synthesis Example 8 was made into a 3% acetone solution, sprayed onto the inner surface of the polymerization vessel used in Comparative Example 1, and dried. The amount of coating at this time was 0.4 g/go.

When a polymerization reaction was carried out in the same manner as in Comparative Example 1 using this polymerization vessel, the amount of scale deposited was as shown in Table 1.

(Examples 1 to 7) Each of the products obtained by the methods of Synthesis Examples 1 to 7 was made into a 3% acetone solution, sprayed onto the inner surface of the polymerization vessel used in Comparative Example 1, and dried.

The coating amount at this time was 0.4 g/rri'.

Using this polymerization vessel, a polymerization reaction was carried out in the same manner as in Comparative Example 1, and the scale adhesion amounts were as shown in Table 1.

(Comparative Example 3) In the same polymerization vessel as used in Example 1, 190k vinyl chloride was added.
g, 1 kg of vinyl acetate, 450 kg of pure water, 180 g of partially saponified polyvinyl acetate, and 60 g of azobisdimethylvaleronitrile were added, and polymerization was carried out at 60° C. with stirring for 10 hours.

After the polymerization was completed, the polymerization vessel was washed with water under a pressure of 5 atm, and the amount of scale attached was measured. Table 2 shows the results.

(Comparative Example 4) The product obtained by the method of Synthesis Example 8 was made into a 3% acetone solution, sprayed onto the inner surface of the polymerization vessel used in Comparative Example 3, and dried. The amount of coating at this time was 0.4 g/go.

When a polymerization reaction was carried out in the same manner as in Comparative Example 3 using this polymerization vessel, the amount of scale deposited was as shown in Table 2.

(Examples 8 to 14) Each of the products obtained by the methods of Synthesis Examples 1 to 7 was made into a 3% acetone solution, sprayed onto the inner surface of the polymerization vessel used in Comparative Example 3, and dried.

The coating amount at this time was 0.4 g/rrf'.

Using this polymerization vessel, a polymerization reaction was carried out in the same manner as in Comparative Example 3, and the scale adhesion amounts were as shown in Table 2.

(Comparative Example 5) In the same polymerization vessel as used in Example 1, chlorobrene 200
kg, polyoxyethylene tallow alkylpropylene diamine 8) cg, acetic acid 2 kg, alumina sol 1 dan, sodium formaldehyde sulfoxylate 0.04 kg
Then, 200 kg of pure water was added, and the polymerization was completed in 10 hours at 40° C. while adding 0.02 kg of t-butyl hydroperoxide.

After polymerization, the polymerization vessel was washed with water under a pressure of 5 atm, and scale adhesion was determined by Mj. Table 3 shows the results.

(Comparative Example 6) The product obtained by the method of Synthesis Example 8 was made into a 3% acetone solution, sprayed onto the inner surface of the polymerization vessel used in Comparative Example 5, and dried. The amount of coating at this time was 0.4 g/I.

When a polymerization reaction was carried out in the same manner as in Comparative Example 5 using this polymerization vessel, the results regarding scale adhesion were shown in Table 3.

(Examples 15 to 21) Each of the products obtained by the methods of Synthesis Examples 1 to 7 was made into a 3% acetone solution, sprayed onto the inner surface of the polymerization vessel used in Comparative Example 5, and dried.

The coating values at this time were 0 and 4 g/d, respectively.

Using this polymerization vessel, a polymerization reaction was carried out in the same manner as in Comparative Example 5, and the scale adhesion amounts were as shown in Table 3.

Table 1 Table 2 Table 3 *1 The effective number of batches in the table refers to the fact that the scale adhesion prevention effect is lost because the applied scale adhesion preventive agent peels off due to slurry stirring due to polymerization, or that the quality of foreign matter, color, etc. It means the number of batches that can be effectively used until it becomes practically impossible to continue polymerization without washing due to adverse effects.

[Effects of the Invention] As explained above, the present invention significantly reduces the amount of scale deposited and improves the durability of the coating film, thereby improving the number of effective batches.

Claims (1)

[Scope of Claims] 1) When a vinyl monomer is polymerized in an aqueous medium, a reaction product of a polymeric alcohol having a hydroxyl group in the molecule, a phenolic compound, and optionally an aldehyde compound, A method for polymerizing vinyl monomers, which is characterized by coating the inner surface of a polymerization vessel 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 polymerization method according to claim 1, wherein the polymeric alcohol having a hydroxyl group in the molecule is polyvinyl alcohol obtained by saponifying polyvinyl acetate. 4) The polymerization method according to claim 1, wherein the phenolic compound is pyrogallol and/or hydroxyhydroquinone.