JPH1060008A - Polymerization of vinyl chloride - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a practical polymerization method exhibiting sufficient polymer deposition prevention effect in the homo- or copolymerization of vinyl chloride without exerting adverse effect on the polymerization time and the quality of the product, etc., and to provide a polymer deposition preventing agent to be used in the polymerization method. SOLUTION: A coating liquid containing a cocondensate produced by reacting a polyhydric phenol with a precondensate of a 2-naphthol and an aldehyde is applied to the surface of the inner wall of a polymerizer and a part of the polymerization equipment to be brought into contact with monomers during the polymerization process in the homopolymerization of vinyl chloride monomer or the copolymerization of the monomer with a copolymerizable monomer in an aqueous medium or in bulk state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved method for homo- or copolymerization of vinyl chloride, and more particularly, to the prevention of polymer adhesion to the inner wall of a polymerization tank and to a portion of an apparatus which is in contact with a monomer during a polymerization operation. The present invention relates to a method and a polymer adhesion inhibitor used therein.

[0002]

2. Description of the Related Art Polymerization of vinyl chloride alone or with a monomer copolymerizable therewith (hereinafter simply referred to as "polymerization")
During the polymerization, the polymer adheres to the parts of the equipment that the monomer comes into contact with during the polymerization operation, such as the inner wall of the polymerization tank, reflux condenser, stirring blade, baffle plate, and various attachment pipe connection parts. In addition, there is a problem that the polymer which has been adhered and then peeled off is mixed into a vinyl chloride homopolymer or copolymer (hereinafter referred to as [product]) to lower the quality. Therefore, after polymerization is completed, it is customary to wash the inside of the polymerization tank with high-pressure water each time and then polymerize again. In addition, the cost of the product is increased, or the quality of the product is lowered due to the incorporation of the polymer adhering to the wall into the product.

Therefore, there has been proposed a method for preventing a polymer from adhering by applying a coating liquid to the inner wall of a polymerization tank and other parts.

For example, Japanese Patent Publication No. 61-843 proposes a method of applying a co-condensate of resole and a nitrogen-containing compound, and Japanese Patent Publication No. 1-35233 proposes a method of applying a single condensate of 1-naphthol. Have been.

Also, Japanese Patent Publication No. Hei 1-31523, page 5, 9
The column, from line 13 to line 26, states that the condensate of 2-naphthol is insoluble in aqueous alkali solutions and has a poor polymer adhesion-preventing effect even when used after being dissolved in an organic solvent. .

[0006]

However, according to JP-B-61-843 and JP-B1-31523, a sufficient scale adhesion preventing effect cannot be obtained yet.
A more effective method is desired.

It is an object of the present invention to provide a practical polymerization method which exerts a sufficient polymer adhesion preventing effect upon homo- or copolymerization of vinyl chloride and does not adversely affect polymerization time, product quality, and the like.

[0008]

Means for Solving the Problems As a result of repeated studies, the present inventors have found that when vinyl chloride is polymerized, it is necessary to attach the polymerizer to the inner wall of the polymerization tank and other parts of the polymerization equipment and polymerization accessories that come into contact with the monomer during the polymerization operation. It has been found that if a certain kind of coating liquid is applied in advance, the adhesion of the polymer is greatly reduced, and the polymer adhered in a small amount can be easily removed by washing with water or the like, and the present invention described below has been achieved. That is,
The present invention includes the following inventions. When the vinyl chloride monomer is polymerized alone or together with a monomer copolymerizable therewith in an aqueous medium or in a bulk, the inner wall of the polymerization tank and the part of the device that comes into contact with the monomer during the polymerization operation are previously 2- A method for homopolymerizing or copolymerizing vinyl chloride, wherein a coating solution containing a cocondensate obtained by further reacting a polyhydric phenol with an initial condensate of a naphthol and an aldehyde is applied to the surface. A basic substance is added to the initial condensate obtained by reacting a 2-condensate of the coating solution with 2-naphthols and aldehydes in the presence of a strong acidic catalyst, and the pH is adjusted from 2 to 7, and then a polyhydric phenol is added. In addition, the method according to the above description, which is a modified co-condensate obtained by further reacting. The method according to claim, wherein the coating liquid is an aqueous alkaline solution of the cocondensate. A co-condensate obtained by further reacting a polyhydric phenol with an initial condensate of 2-naphthols and aldehydes. A basic substance is added to the initial condensate obtained by reacting the 2-condensate with a 2-naphthol and an aldehyde in the presence of a strongly acidic catalyst, the pH is adjusted from 2 to 7, and then a polyhydric phenol is added. A modified co-condensate as described which is obtained by reacting.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The polymerization to which the present invention can be applied includes not only homopolymerization of vinyl chloride but also monomers copolymerizable with vinyl chloride, for example, olefins such as ethylene and propylene, vinyl acetate, styrene and the like. For copolymerization with vinyl monomers, acrylonitrile, acrylic monomers such as acrylic acid esters, maleic acid, maleic acid esters, fumaric acid, dicarboxylic acid monomers such as fumaric acid esters, and acrylic rubbers. Can be applied effectively. These monomers to be copolymerized can be used within a range not exceeding 50% by weight based on vinyl chloride.

The polymerization method to which the present invention can be applied includes aqueous suspension polymerization, aqueous emulsion polymerization of vinyl chloride monomer or a monomer copolymerizable therewith, and vinyl chloride monomer or vinyl chloride monomer. It can be effectively applied to so-called bulk polymerization using a copolymerizable monomer itself as a polymerization medium under each condition.

The cocondensate used in the present invention is a cocondensate obtained by previously reacting a polyhydric phenol with an initial condensate of a 2-naphthol and an aldehyde. The 2-naphthols used in the present invention include:
Any 2-naphthols can be used without limitation and can be used by mixing, but 2-naphthol and 2,3-dihydroxynaphthalene are particularly preferable.

As the aldehyde, an organic compound having a CHO group can be used, for example, formaldehyde, acetaldehyde, benzaldehyde and the like, and these can be used alone or in combination.

Examples of the polyhydric phenol include resorcin, hydroquinone, pyrogallol, and hydroxyhydroquinone, and pyrogallol is particularly preferred.

[0014] In the present invention, first, 2-
A precondensate of naphthols and aldehydes is synthesized. The amount of the strongly acidic catalyst is preferably 0.02 to 0.5 mol, more preferably 0.05 to 0.3 mol, based on 1.0 mol of 2-naphthols. In this case, aldehydes are used in excess of 2-naphthols. 2
Aldehydes are:
1.1 to 3.0 mol is preferable, and more preferably,
It is in the range of 1.2 to 2.0 moles. The reaction is generally 60
Performed at ~ 90 ° C for 1-6 hours.

Examples of the strong acidic catalyst include sulfuric acid, hydrochloric acid, p-toluenesulfonic acid and hydrates thereof, preferably hydrochloric acid, p-toluenesulfonic acid and hydrates thereof.

Next, a basic substance is added to the synthesized initial condensate to adjust the pH to 2 to 7, preferably 3 to 5. pH2
If the pH is less than 7, the next reaction proceeds to a high degree, the molecular weight of the co-condensate increases, and the viscosity of the coating solution may become high, making application difficult. Conversely, if the pH exceeds 7, the next reaction hardly proceeds, and the molecular weight is reduced. If the coating liquid is applied too low, the coating liquid flows from the surface to be applied, making it difficult to form a coating film, which is not preferable. Examples of the basic substance used at this time include sodium hydroxide and potassium hydroxide.

Next, a polyhydric phenol is added to the pH-adjusted initial condensate, and the mixture is reacted at a reaction temperature of 60 to 90 ° C. for 1 to 6 hours. The amount of the polyhydric phenol is preferably 0.1 to 0.6 mol, more preferably 0.2 to 0.4 mol, per 1 mol of the 2-naphthol.

The molecular weight of the final reaction product is an important factor. According to the experimental results, a good polymer adhesion preventing effect is obtained at a molecular weight of 300-5000, preferably 400-30.
Obtained when in the range of 00.

In the study of the present inventors, the reaction of the initial condensate of 2-naphthols and aldehydes under acidic conditions is complicated, and the molecular structure of the condensate cannot be determined. According to NMR analysis, some methylol groups were detected together with the methylene groups. The reactivity under alkaline conditions was extremely lower than under acidic conditions.

In the cocondensate of the initial condensate and the polyhydric phenol, a methylene group was detected and no methylol group was detected by NMR analysis.

In the present invention, it is desirable to carry out the reaction in the presence of a general solvent. Examples of the solvent include, but are not limited to, benzene, toluene, diethylene glycol, dioxane, methyl isobutyl ketone, and the like.

Although the rationale for preventing the adhesion of the polymer by applying the coating solution containing the co-condensate of the present invention to the inner wall of a polymerization tank of vinyl chloride or the like is not clear, it is probably that the side chain of the co-condensate is It is considered that the located hydroxyl group has a radical scavenging effect and prevents polymerization of vinyl chloride on the inner wall surface of the polymerization tank.

In carrying out the present invention, the coating solution is an aqueous alkali solution, and the concentration of the coating agent is 0.05 to 5.0 wt%, preferably 0.1 to 2.0 w%.
It is dissolved in an aqueous solution of sodium hydroxide so as to be t%.

Usually, the coating solution is used as an alkaline aqueous solution, but a solution dissolved in an organic solvent can also be used. However, the use of an alkaline aqueous solution makes it unnecessary to collect the solvent from the viewpoint of safety. Is preferred.

In the method of the present invention, it is necessary to apply the coating solution to the inner wall surface of the polymerization tank under the above conditions. The application method is not particularly limited, and for example, the application can be carried out by brush application of a coating liquid or by a general method such as spraying, rinsing, or an ejector method. The surface to be coated may be dry or wet with water, and is not particularly limited. The coating amount is usually 0.001 per coating surface as a coating agent.
5 to 5.0 g / m ² is sufficient, preferably 0.05 g / m ^2.
It is in the range of 1 to 3.0 g / m ² .

After applying the coating liquid, the surface to be coated may or may not be washed with water, but it is preferable to wash and remove the excess coating agent from the viewpoint of preventing the influence on the polymerization reaction or mixing into the product. preferable.

The above-mentioned coating solution may be applied before the start of polymerization in each batch, or may be applied every several batches. As a result, after each batch, polymerization can be continuously carried out only by simple washing with water.

[0028]

The present invention will be described more specifically with reference to the following examples. Production Example 1 (Synthesis of co-condensate of 2-naphthol and pyrogallol) In a 1-liter three-necked flask equipped with a reflux condenser, 37.5 g (0.260 mol) of 2-naphthol and dioxane 200
ml, 37% by weight formalin 31.7 g (0.391 mol), palladium toluenesulfonic acid monohydrate 2.94 g
(0.0155 mol) and heated to 80 ° C. Further, the reaction was carried out for 2 hours while maintaining this temperature. Thereafter, the temperature was lowered to 40 ° C., and the pH was adjusted to 4 by adding a 5.2% aqueous sodium hydroxide solution. Thereafter, 9.85 g (0.0782 mol) of pyrogallol was added and dissolved, and the temperature was raised to 80 ° C.

Further, the reaction was carried out for 3 hours while maintaining this temperature. Then, after cooling down and sampling partly,
A 26% aqueous sodium hydroxide solution was charged. The weight-average molecular weight (hereinafter abbreviated as [Mw]) of the obtained reaction product is as follows:
It was found to be 544 by a gel permeation chromatograph (hereinafter abbreviated as [GPC]) method.

Production Example 2 (Synthesis of a single condensate of 1-naphthol) 7.5 g (0.0521 mol) of 1-naphthol and 40 m of dioxane were placed in a 200 ml three-necked flask equipped with a reflux condenser.
1, 3.44 g (0.0781 mol) of paraacetaldehyde, 0.297 g of paratoluenesulfonic acid monohydrate
(0.00156 mol) and heated to 80 ° C. Further, the reaction was carried out for 4 hours while maintaining this temperature.
Thereafter, the temperature was lowered. The Mw of the obtained reaction product was found to be 489 by GPC measurement. This reaction product was insoluble in the aqueous alkali solution.

Production Example 3 (Synthesis of phenolic resole) In a 300 ml three-necked flask equipped with a reflux condenser, 37.5 g (0.399 mol) of 1-naphthol, 48.5 g (0.599 mol) of 37% by weight formalin, 0.638 g (0.016 mol) of sodium hydroxide was charged, and the temperature was raised to 85 ° C. Further, the reaction was carried out for 2 hours and 40 minutes while maintaining this temperature.

After cooling to 40 ° C., 1.5 g of 0-secondary-butylphenol (0.
01 mol), 7.67 g (0.
040 mol) and dissolved, and then heated to 75 ° C. The reaction was continued while maintaining this temperature. When the temperature reached 1000 cP using a B-type viscometer, the temperature was lowered and 2
A 6% aqueous sodium hydroxide solution was charged. The Mw of the obtained reaction product was found to be 1,430 by GPC measurement.

Preparation Example 1 of Coating Solution The reaction product obtained in Preparation Example 1 and partially sampled was diluted with methanol to prepare a methanol solution having a coating agent concentration of 0.05%.

Preparation Example 2 of Coating Solution The alkaline aqueous solution obtained in Preparation Example 1 was diluted with water to give a coating agent concentration of 0.3% and a sodium hydroxide concentration of 0.1%.
It was adjusted to 1%.

Preparation Example 3 of Coating Solution The reaction product obtained in Production Example 2 was diluted with methanol,
It was prepared so as to be a methanol solution having a coating agent concentration of 0.05%.

Preparation Example 4 of Coating Liquid The alkaline aqueous solution obtained in Production Example 3 was diluted with water to prepare a coating agent concentration of 1.0% and a sodium hydroxide concentration of 0.2%.

Example 1 After removing the air inside a polymerization reactor having a reflux condenser with an internal volume of 840 liters by a vacuum pump, a vinyl chloride monomer was adjusted so that the internal pressure of the polymerization reactor became 0.1 kg / cm ² · G. Then, warm water was circulated through the jacket to adjust the wall temperature of the polymerization tank to 60 ° C. Thereafter, 1 liter of the coating liquid of Preparation Example 2 of the above-described coating liquid was sprayed onto the inner wall of the polymerization reaction tank and applied.
The inside of the polymerization reaction tank was sufficiently washed with water. Next, 26 liters of deionized water were charged, and then a saponification degree of 80 mol was used as a dispersant.
%, Polyvinyl alcohol having a polymerization degree of 2,000
7 parts by weight (parts by weight based on 100 parts by weight of vinyl chloride monomer, the same applies hereinafter), saponification degree 70 mol%, polymerization degree 700
Was charged, and then 229 kg of vinyl chloride monomer was charged. As a polymerization initiator, 167 g of a water emulsion of dioctyl peroxycarbonate having a purity of 60% by weight and 64 g of a water emulsion of α-cumyl peroxyneodecanate having a purity of 50% by weight were pumped.

The reaction temperature was raised to 57.8 ° C. to start the polymerization reaction. After 4 hours and 30 minutes, an aqueous suspension of a phenolic antioxidant was charged by a pump, the slurry was discharged from the polymerization tank, the monomer was removed through a demonomerization step, dewatered, and dried to obtain a PVC resin. I got After discharging the PVC slurry, the polymerization tank is washed with water without opening the upper mirror (the upper lid of the polymerization reaction tank, the same applies hereinafter), and the raw material of the next batch is charged without applying the coating liquid, and the second polymerization is performed. went. Thereafter, the polymerization was continuously performed for the third time and the fourth time, and the
Polymerization was performed up to the batch. After completion of 10 batches, the adhered polymer in the polymerization machine was recovered, dried, and weighed. The results are shown in Table 1.

Comparative Example 1 Preparation Example 2 of Coating Solution
Polymerization was carried out in the same manner as in Example 1 except that the polymerization was changed to. The results are shown in Table 1.

Example 2 Using a 7 liter internal volume polymerization reactor, the coating solution of Preparation Example 1 was coated on the inner wall of the polymerization reactor.
ml was sprayed and applied.

Thereafter, methanol was purged with nitrogen gas. Next, 3 liters of deionized water were charged, and then 0.05 parts by weight of polyvinyl alcohol having a degree of saponification of 80 mol% and a degree of polymerization of 2000 and 0.10 parts by weight of polyvinyl alcohol having a degree of saponification of 70 mol% and 700 were charged as dispersants. After the introduction, the air inside the polymerization tank was removed by a vacuum pump.

Thereafter, 1200 g of vinyl chloride, 0.970 g of a water emulsion of dioctyl peroxydicarbonate having a purity of 60% by weight as a polymerization initiator and 0.95 g of a purity of 5% were used.
0.372 g of a 0% by weight aqueous emulsion of α-cumylperoxyneodecanate was charged. The reaction temperature was 57.
The temperature was raised to 8 ° C. to initiate polymerization. After 4 hours and 40 minutes, the reaction was completed. After that, unreacted monomers were recovered, and after discharging the polymer, the inner surface of the polymerization reactor was rinsed with water.

Next, the next batch of raw materials was charged without applying the coating liquid, and the second polymerization was carried out. Thereafter, the polymerization was continuously performed for the third and fourth times, and the polymerization was continuously repeated 10 times. After completion of 10 batches, the adhered polymer in the polymerization machine was recovered, dried, and weighed. Table 1 shows the results.

Comparative Example 2 Preparation Example 1 of Coating Solution
The polymerization was carried out in the same manner as in Example 2 except that The results are shown in Table 1.

Test Methods Tests and measurement methods for the polymers obtained in the above Examples and Comparative Examples are as follows.

Average degree of polymerization: JIS K-6721 Apparent specific gravity: JIS K-6721 Fish eye: A mixture of a polymer and a predetermined amount of a plasticizer, a heat stabilizer and the like is kneaded at 150 ° C. for 5 minutes, and has a thickness of 0.3.
Create a mm sheet. After 10cm x 10cm
The number of spots existing in the area is counted visually. Porosity: By mercury intrusion method.

[0047]

[Table 1]

[0048]

According to the conventional method, after the homopolymerization or copolymerization of vinyl chloride is carried out, a large amount of polymer adheres to the polymerization machine. To remove the polymer, high-pressure water washing is performed after every several batches. Had to do. However, by carrying out the method of the present invention, the adhesion of the polymer is extremely reduced, and the polymer can be dropped off only by performing simple water washing, and it is sufficient to perform high pressure water washing once every several tens of batches. became. Moreover, there is no adverse effect on the polymerization rate or the product.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasuyuki Hatakeyama 1-6-6 Takasago, Takaishi-shi, Osaka Prefecture Inside Mitsui Toatsu Chemical Co., Ltd. (72) Inventor Tadashi 1-6-6 Takasago, Takaishi-shi, Osaka Mitsui Toatsu Chemical Inside the company

Claims (5)

[Claims] In the polymerization of a vinyl chloride monomer, alone or together with a monomer copolymerizable therewith, in an aqueous medium or in a bulk, the inner wall of a polymerization tank and a portion of an apparatus which comes into contact with the monomer during a polymerization operation. Coating a coating solution containing a co-condensate obtained by further reacting a polyhydric phenol with an initial condensate of a 2-naphthol and an aldehyde on the surface, Copolymerization method. 2. A basic substance is added to an initial condensate obtained by reacting a 2-condensate of the coating solution with 2-naphthols and aldehydes in the presence of a strong acid catalyst, and a pH of 2 to 7 is added.
2. The method according to claim 1, wherein the modified cocondensate is obtained by adding a polyhydric phenol and then reacting the mixture. 3. The method according to claim 1, wherein the coating liquid is an aqueous alkaline solution of the co-condensate. 4. A co-condensate obtained by further reacting a polyhydric phenol with an initial condensate of a 2-naphthol and an aldehyde. 5. A basic substance is added to an initial condensate obtained by reacting a 2-naphthol and an aldehyde with the co-condensate in the presence of a strongly acidic catalyst, and the pH is adjusted to 2 to 7 to obtain a polyhydric phenol. 5. The modified co-condensate according to claim 4, wherein the co-condensate is obtained by adding a compound and further reacting.