JP2001026620A - Preparation of vinyl chloride-based copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a preparing process for a vinyl chloride-vinyl ether copolymer having a relatively higher copolymerization ratio, for example 10 wt.% or more, of the vinyl ether by a suspension polymerization with the more stability and lower cost than those at a bulk polymerization process and a solution polymerization one. SOLUTION: A preparing process for a vinyl chloride-based copolymer, copolymerizing 80-20 mole % of a vinyl chloride monomer and 20-80 mole % of a vinyl ether monomer copolymerizable with the vinyl chloride monomer by a suspension polymerization, comprises an addition of a pH buffer so that the pH in the polymerization system may be maintained to be above 7 from the initial period of the polymerization to the ending time thereof along with an addition, divided or continuous, of a vinyl chloride monomer into the system preferably during the polymerization advance so that a monomer composition ratio in the polymerization may be maintained to be of the same one as is at a feed time in the initial period.

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-vinyl ether copolymer,
The present invention relates to a method for producing a vinyl chloride-vinyl ether copolymer having a higher vinyl ether copolymerization ratio than before.

[0002]

2. Description of the Related Art As a method for producing a vinyl chloride-vinyl ether copolymer, a bulk polymerization method (Polymer Chemistry, Vol. 17, N.
o. 184, p. 478-482 (1960)) and a solution polymerization method (Polymer Chemistry, Vol. 29, No. 323, pp. 168-172 (1972)). However, when attempting to industrially produce a vinyl chloride-vinyl ether copolymer, the bulk polymerization method requires heat removal during the polymerization, and the solution polymerization method requires man-hours in the purification step of the copolymer. This is disadvantageous in terms of cost. Therefore, it is preferable to produce by the suspension polymerization method most frequently used for industrial production of polyvinyl chloride, because the production process and the purification process can be simplified and the cost is advantageous.

[0003] With respect to the suspension polymerization method of vinyl chloride-vinyl ether, for example, Japanese Patent Laid-Open No. 2-243 discloses a resin material containing a vinyl chloride-vinyl ether copolymer as a main component.
No. 42 discloses this. Specifically, the publication discloses an example in which vinyl chloride and an alkyl vinyl ether are charged into an autoclave to carry out suspension polymerization, but the amount of vinyl ether copolymerized with vinyl chloride is 100%. It is described that if the amount exceeds 10 parts by weight with respect to the parts by weight, the strength and the transparency deteriorate, which is not preferable. Therefore, it is natural that the ratio of the alkyl vinyl ether exceeds 10 parts by weight. No polymerized vinyl chloride-vinyl ether copolymer is disclosed. That is, a method of industrially producing a vinyl chloride-vinyl ether copolymer having a relatively high copolymerization ratio of vinyl ether by suspension polymerization has not been reported so far.

[0004]

SUMMARY OF THE INVENTION The present inventors have studied to obtain a vinyl chloride-vinyl ether copolymer having a relatively high vinyl ether copolymerization ratio. In the suspension polymerization method, which is also conventionally known in the suspension polymerization method, the ratio of vinyl ether in the obtained copolymer is significantly lower than the charge ratio due to the difference in the monomer reactivity ratio between vinyl chloride and vinyl ether.
When an attempt is made to produce the copolymer having a high content of vinyl ether, it is not possible to obtain a copolymer having a stable particle size distribution due to formation of a coarse-grained product or a block-like polymer, and further, in the copolymer. Problems such as the composition distribution being broadened and the solubility in organic solvents being reduced were confirmed.

The present invention has been made to solve the problems found by the present inventors with respect to the above-mentioned vinyl chloride-vinyl ether copolymer, and an object of the present invention is to make the copolymerization ratio of vinyl ether, for example, 10% by weight. It is an object of the present invention to provide a method for producing a relatively high vinyl chloride-vinyl ether copolymer at a lower cost and more stably by a suspension polymerization method than a bulk polymerization method and a solution polymerization method. Another object of the present invention is to provide a method for producing a vinyl chloride-vinyl ether copolymer having good solubility in a solvent.
Still another object of the present invention is to provide a method for producing a vinyl chloride-vinyl ether copolymer having a high copolymerization ratio of vinyl ether and having good solubility in an organic solvent by a suspension polymerization method. Is to do.

[0006]

In order to achieve the above-mentioned object, the present invention according to claim 1 comprises a vinyl chloride monomer 80
When a mole% to 20 mole% of a vinyl ether monomer copolymerizable with a vinyl chloride monomer is copolymerized with a mole ratio of 20 to 80 mole% by a suspension polymerization method, from the initial stage to the end of the polymerization, Provided is a method for producing a vinyl chloride copolymer in which a pH buffer is added so as to maintain the pH at 7 or more.

[0007] The present invention according to claim 2 provides a method for producing a vinyl chloride monomer comprising from 80 mol% to 20 mol%, and 20 mol% of a vinyl ether monomer copolymerizable with the vinyl chloride monomer.
To 80 mol% by the suspension polymerization method, during the progress of the polymerization, the vinyl chloride monomer was added to the polymerization system so that the monomer composition ratio in the polymerization system maintained the monomer composition ratio at the time of initial charging. And a method for producing a vinyl chloride-based copolymer according to claim 1, wherein the method is divided addition or continuous addition.

[0008] The present invention according to claim 3 is characterized in that the vinyl chloride monomer is 75 mol% to 25 mol%, and the vinylether monomer copolymerizable with the vinyl chloride monomer is 25 mol%.
2 to 75 mol% by a suspension polymerization method.
Or a method for producing a vinyl chloride copolymer according to item 2.

Hereinafter, the present invention will be described in more detail. Note that the description limited to any one of claims 1 to 3 is clearly stated to that effect, and when simply described as the present invention, it is not limited to each claim.

The type of the vinyl ether monomer to be copolymerized with vinyl chloride in the above polymerization system in the present invention is not particularly limited as long as it has copolymerizability with vinyl chloride. Specifically, for example, methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i
alkyl vinyl ethers such as so-propyl vinyl ether, n-butyl vinyl ether and iso-butyl vinyl ether; alkenyl vinyl ethers such as allyl vinyl ether; cyclohexyl vinyl ether; 4-n-
Cycloalkyl vinyl ethers such as butylcyclohexyl vinyl ether; substituted phenyl vinyl ethers such as phenyl vinyl ether and 2-methyl-5-isopropylphenyl vinyl ether; haloalkyl vinyl ethers such as 1-chloroethyl vinyl ether and 3-chloropropyl vinyl ether; 1-hydroxyethyl vinyl ether; No.

The composition ratio of the vinyl ether monomer to be copolymerized with vinyl chloride must be changed depending on the content and type of vinyl ethers in the copolymer to be obtained. The composition ratio is 80 mol% of vinyl chloride. ~
20 mol% to 80 mol% of vinyl ether with respect to 20 mol%. When the charged composition ratio of vinyl ether is less than 20 mol%, the vinyl ether content in the obtained copolymer is greatly reduced, and when it is more than 80 mol%, the production rate of the copolymer is reduced, and the productivity is deteriorated. It is limited to the above range. More preferably, the content of vinyl ether monomer is 25 mol% to 75 mol% with respect to 75 mol% to 25 mol% of vinyl chloride.

The vinyl chloride-vinyl ether copolymer in the present invention is produced by a suspension polymerization method, and uses a dispersant and an oil-soluble polymerization initiator which are generally used for suspension polymerization of a polyvinyl chloride copolymer. Can be.

As a specific method of the suspension polymerization in the present invention according to the first aspect, for example, a reaction vessel equipped with a stirrer and a jacket is charged with pure water, the vinyl ether monomer, a pH buffer, a dispersant, and an oil. After charging a predetermined amount of the soluble polymerization initiator, vinyl chloride monomer is charged, and the inside of the reaction vessel is heated to a required temperature by a jacket to start the polymerization, and the copolymerization of vinyl chloride and vinyl ether is performed for a predetermined time. There is a method of performing.

The polymerization temperature in the above suspension polymerization method is not particularly limited, but is preferably in the range of 40 ° C. to 80 ° C. where the temperature can be easily controlled in industrial production. The type of the pH buffer is not particularly limited as long as it can maintain the pH of the system at 7 or more. Normally, in the polymerization of vinyl chloride, the generation of unsaturated bonds on the main chain causes elimination of hydrogen chloride and shifts the pH in the system to an acidic side. When the pH is lower than 7, the hydrolysis of the coexisting vinyl ether is promoted, the vinyl ether content of the obtained copolymer is reduced, and the polymerization system is also unstable, so that a copolymer having a stable particle size distribution is obtained. Disappears. Therefore, it is necessary to maintain the pH in the system at 7 or more.

Examples of the pH buffer include Sor
Ensen's buffer, Clark-Lub's buffer,
Kolthoff buffer, Michaelis buffer, Gomori buffer, Bates-Bower Tris buffer, and the like.
It is prepared to be maintained at 7 or more. Further, the amount of the pH buffer added depends on the buffer capacity of the pH buffer.
Further, they may be added all at once in the early stage of the polymerization, or may be added as needed during the polymerization reaction.

The dispersing agent used in the above suspension polymerization is added in order to keep the oil droplet diameter in the polymerization system at an appropriate level, and is not particularly limited as long as it is generally used for suspension polymerization of a polyvinyl chloride polymer. It is not something to be done. Examples of the dispersant include poly (meth) acrylate, (meth) acrylate-alkyl acrylate copolymer, methyl cellulose,
Ethyl cellulose, hydroxypropyl methylcellulose, polyethylene glycol, polyvinyl acetate and partially saponified products thereof, gelatin, polyvinylpyrrolidone, starch, maleic anhydride-styrene copolymer and the like, and these can be used alone or in combination of two or more kinds it can.

Among the above oil-soluble polymerization initiators, a radical polymerization initiator is preferably used because it is advantageous for vinyl chloride copolymerization. Examples thereof include lauroyl peroxide, t-butylperoxypivalate, and diisopropyl peroxide. Organic peroxides such as peroxydicarbonate, dioctyl peroxycarbonate, t-butyl peroxyneodeanoate, α-cumylperoxyneodecanate, 2,2-azobisisobutyronitrile, 2,2 And azo compounds such as -azobis-2,4-dimethylvaleronitrile. The amount of the oil-soluble polymerization initiator to be used is generally set so that the polymerization time is about 2 to 20 hours.

In the above suspension polymerization method, an antioxidant may be added as necessary. Since the copolymerization of vinyl chloride and vinyl ether is an exothermic reaction, it is possible to control the temperature in the reaction vessel, that is, the polymerization temperature by changing the jacket temperature. After completion of the reaction, unreacted vinyl chloride is removed to form a slurry, and the slurry is dehydrated and dried to produce a vinyl chloride-vinyl ether copolymer.

As a specific method of the above-mentioned suspension polymerization in the case of the present invention described in claim 2, first, as in the case of the above-mentioned claim 1, for example, a reaction vessel equipped with a stirrer and a jacket may be used. After charging predetermined amounts of pure water, the above-mentioned vinyl ether monomer, pH buffer, dispersant, and oil-soluble polymerization initiator, vinyl chloride monomer is charged, and the inside of the reaction vessel is heated to a required temperature by a jacket to start polymerization. Let it. These conditions are the same as in the case of the present invention described in claim 1, and
Of course, there is nothing different.

After the polymerization is started, in the case of the present invention according to the second aspect, the vinyl chloride monomer is dividedly added or continuously added, and cooling is usually performed when the polymerization conversion of the vinyl ether monomer reaches 80%. To complete the polymerization. The divided addition or continuous addition of the vinyl chloride monomer in the above suspension polymerization method preferably starts after the polymerization conversion of the vinyl ether monomer has reached 1 to 10% by weight, and 70% or more of the total charged vinyl ether monomer is polymerized. Continue until you do.

The amount of the vinyl chloride monomer added depends on the polymerization conversion of the vinyl ether monomer at the time of addition.
The composition ratio between the vinyl chloride monomer and the vinyl ether monomer in the polymerization system is determined so as to maintain the initial charge composition ratio.

[0022]

The present invention will be described in more detail with reference to Examples and Comparative Examples. Note that the present invention is not limited to the following embodiments. The powder properties of the vinyl chloride-vinyl ether copolymer were evaluated by the following methods.

<PH in system at the end of polymerization> After the polymerization reaction is completed, an appropriate amount of a slurry containing a vinyl chloride-vinyl ether copolymer is collected from the polymerization tank, and the collected slurry is filtered. The pH was measured using a commercially available pH meter.

<Polymerization degree> The polymerization degree of the vinyl chloride-vinyl ether copolymer is determined in accordance with JIS K6721.
It was measured.

<Vinyl Ether Content in Copolymer> The chlorine content of the vinyl chloride-vinyl ether copolymer (C1
%) Was measured in accordance with JIS K7229, and the vinyl ether content in the copolymer was calculated from the result according to the following formula. Vinyl ether content (% by weight) = (1-C1 / 56.
73) x 100

<Particle Size Distribution> The particle size distribution of the vinyl chloride-vinyl ether copolymer was measured according to JIS Z8801.

<Amount of Insoluble Particles> 15 g of the obtained resin and 60 g of toluene were placed in a sealed 200 ml wide-necked flask, and stirred for 10 hours with a bottle roller to obtain a 2020% by weight resin solution. Equipment (Rion,
Solution 1 using a particle counter KL-01)
Insoluble particles of 10 μm or more in 0 ml were measured.

Examples 1 to 5 and Comparative Examples 1 to 3 (Preparation of vinyl chloride-vinyl ether copolymer) In a polymerization vessel equipped with a stirrer and a jacket, pure water, vinyl ether monomer, pH A buffer, a 3% aqueous solution of partially saponified polyvinyl acetate, t-butyl peroxy neodecanoate and α-cumyl peroxy neodecanoate are added all at once, and then the air inside the polymerization reactor is discharged by a vacuum pump. Then, after vinyl chloride was charged under stirring conditions, copolymerization was started at a polymerization temperature of 50 ° C to 78 ° C by controlling the jacket temperature. The copolymerization reaction was performed for about 4 to 9 hours, and then cooled to stop the reaction.

After the reaction is stopped, the unreacted vinyl chloride monomer is removed, and the vinyl chloride is dehydrated and dried.
A vinyl ether copolymer was obtained. It should be noted that, from the viewpoint of the drying efficiency and the handleability of the resin, it is desirable that the 100-mesh passing (pass) rate of the obtained resin is 50% or more. Table 1 shows some of the powder characteristics of the vinyl chloride-vinyl ether copolymer based on the above evaluation method.

[0030]

[Table 1]

As is clear from Table 1, in Examples 1 to 5, the pH in the system at the end of the polymerization was 7 or more, and the pH in the polymerization system was 7 or more from the beginning of the polymerization to the end of the polymerization. It was confirmed that it had been maintained. In Examples 1 to 5, the alkyl vinyl ether content in the copolymer was higher than in Comparative Examples 1 to 3, and in Example 5, the charged composition was 20 mol%, which was higher than Comparative Examples 1 to 3. Although low, the content in the copolymer is maintained higher than the comparative example. Further, the particle size distributions of Examples 1 to 5 are shown in Comparative Example 1.
As compared with Nos. 1 to 3, it is in a good state, and it can be seen that a coarse-grained product or a block-like polymer is not generated.

Examples 6 to 9 and Comparative Examples 4 to 6 (Preparation of vinyl chloride-vinyl ether copolymer) Pure water, vinyl ether monomer, pH buffer, partial ketone were placed in a polymerization vessel equipped with a stirrer and a jacket. 3% aqueous solution of hydrogenated polyvinyl acetate, t-butyl peroxy neodecanoate, α
-Cumyl peroxy neodecanoate is charged all at once, then the air in the polymerization vessel is exhausted with a vacuum pump, and vinyl chloride monomer is charged under stirring conditions so as to have the monomer composition ratio shown in Table 2. The polymerization was started at a polymerization temperature of 57 ° C. by controlling the jacket temperature.

After the start of the polymerization, when the polymerization conversion of vinyl ether reaches 1 to 10%, the divisional addition of vinyl chloride monomer is started, and when the polymerization conversion of vinyl ether reaches 80%, it is cooled and the polymerization reaction is started. Stopped. After the termination of the polymerization reaction, unreacted vinyl chloride monomer was removed, followed by dehydration drying to obtain a vinyl chloride-vinyl ether copolymer. All the obtained vinyl chloride-vinyl ether copolymers were in the form of powder. Based on the above evaluation method,
Table 2 shows some of the powder characteristics of the vinyl chloride-vinyl ether copolymer. In the table, the vinyl chloride-vinyl ether copolymer is abbreviated as a vinyl chloride copolymer. The particle sizes of the copolymers obtained in Examples 6 to 9 were all good.

[0034]

[Table 2]

[0035]

According to the first aspect of the present invention, there is provided a method for producing a vinyl chloride-based copolymer, wherein the vinyl chloride monomer is 80 to 20 mol%, and the vinyl ether monomer copolymerizable with the vinyl chloride monomer is 20 mol%. To 80 mol% by the suspension polymerization method, from the beginning of the polymerization to the end of the polymerization, the pH in the polymerization system should be maintained at 7 or more.
According to the present invention, since a buffering agent is added, the copolymerization ratio of vinyl ether is, for example, 10% by weight or more, a relatively high vinyl chloride-vinyl ether copolymer having a good particle size distribution. Can be produced more stably at a lower cost than the bulk polymerization method and the solution polymerization method.

According to a second aspect of the present invention, there is provided a method for producing a vinyl chloride copolymer according to the present invention, wherein the vinyl chloride monomer and the vinyl ether monomer in the specific ratio are copolymerized by a suspension polymerization method under the conditions described in the first aspect. During the polymerization, during the progress of the polymerization, the vinyl chloride monomer is added in a divided or continuous manner in the polymerization system so that the monomer composition ratio in the polymerization system maintains the monomer composition ratio at the time of the initial charge. According to the vinyl chloride-vinyl ether copolymer having a high copolymerization ratio of vinyl ether, a copolymer having good solubility in an organic solvent can be obtained more stably at a lower cost than the bulk polymerization method and the solution polymerization method. Can be manufactured.

The method for producing a vinyl chloride-based copolymer according to the third aspect of the present invention is a method for producing a vinyl chloride-based copolymer comprising:
The vinyl chloride copolymer according to claim 1 or 2, wherein 25 to 75 mol% of a vinyl ether monomer copolymerizable with the vinyl chloride monomer is copolymerized by a suspension polymerization method. Because it is a manufacturing method of coalescence,
According to the present invention, in addition to the above, a vinyl chloride-vinyl ether copolymer having a higher vinyl ether copolymerization ratio and a good particle size can be produced with higher productivity. As described above, the vinyl chloride-vinyl ether copolymer produced by the present invention has a high ratio of vinyl ether, has a good particle size distribution, and can exhibit good solubility in an organic solvent. It is suitably used for applications such as ink vehicles.

Continued on the front page F-term (reference) 4J011 JB05 JB09 JB14 4J100 AC03P AE02Q AE03Q AE04Q AE06Q AE09Q AE10Q AE13Q AE35Q BC04Q BC43Q FA21 FA27 FA37

Claims (3)

[Claims] (1) When copolymerizing 80 mol% to 20 mol% of a vinyl chloride monomer and 20 mol% to 80 mol% of a vinyl ether monomer copolymerizable with a vinyl chloride monomer by a suspension polymerization method, from the beginning of polymerization. A method for producing a vinyl chloride copolymer, comprising adding a pH buffer so as to maintain the pH in the polymerization system at 7 or more until the completion of the polymerization. 2. The polymerization progresses when 80 mol% to 20 mol% of a vinyl chloride monomer and 20 mol% to 80 mol% of a vinyl ether monomer copolymerizable with the vinyl chloride monomer are copolymerized by a suspension polymerization method. 2. The vinyl chloride according to claim 1, wherein the vinyl chloride monomer is dividedly or continuously added into the polymerization system such that the monomer composition ratio in the polymerization system maintains the monomer composition ratio at the time of initial charging. A method for producing a copolymer. 3. A method according to claim 1, wherein 75 mol% to 25 mol% of a vinyl chloride monomer and 25 mol% to 75 mol% of a vinyl ether monomer copolymerizable with the vinyl chloride monomer are copolymerized by a suspension polymerization method. Item 3. The method for producing a vinyl chloride copolymer according to Item 1 or 2.