JPH0629292B2 - Manufacturing method of vinyl chloride resin - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a vinyl chloride resin. More specifically, a vinyl chloride resin capable of producing a vinyl chloride resin having various desirable properties such as a vinyl chloride polymer obtained by emulsion polymerization in a preferred form such as a polymer obtained by suspension polymerization. The present invention relates to a manufacturing method of.

"Prior Art" A vinyl chloride polymer produced by an emulsion polymerization method has fine polymer particles and excellent processability. On the other hand, when a vinyl chloride polymer is produced by the suspension polymerization method, the particles produced are coarse, so dehydration after the completion of the polymerization reaction,
Washing and drying are easy, and the resulting polymer has excellent thermal stability, electrical properties, transparency, weather resistance, etc., and is easy to handle during processing.

A method for producing a vinyl chloride resin having preferable properties such as a vinyl chloride polymer obtained by this emulsion polymerization in a preferred form such as a polymer obtained by suspension polymerization is disclosed in, for example, JP-B-45-30842. It is publicly known as described in the publication. This method produces 5 to 90% of the total polymer to be finally obtained by the emulsion polymerization method,
Then, water, a suspending agent and an oil-soluble polymerization initiator are added to the reaction system to cause the rest of the polymerization to be produced by the suspension polymerization method.

"Problems to be solved by the invention" This method, the coarse particles by-produced in the latex obtained by the emulsion polymerization method as it is, and because it does not control the latex agglomerated particles at the stage of the latex, Subsequently, the particle size distribution of the vinyl chloride resin produced by suspension polymerization is not wide and constant, and its swing range is large, which causes the so-called lumps in the molded product to cause fish eyes and can be put to practical use. It was often not. Further, during suspension polymerization, adhesion of polymer scale to the can wall was remarkable.

“Means for Solving Problems” The present inventors make full use of the advantages of the above-mentioned conventional technology,
That is, a vinyl chloride resin having preferable properties such as a vinyl chloride polymer obtained by emulsion polymerization,
Diligent research to develop a method for producing a vinyl chloride resin that has a sharp particle size distribution, can be obtained in a preferred form like a polymer obtained by suspension polymerization, has less adhesion to the can wall, and has easy particle size control. did.

As a result, while removing coarse particles from the emulsion-polymerized latex obtained using the fatty acid ammonium as an emulsifier, after adjusting the hydrogen ion concentration (pH), vinyl chloride or vinyl chloride in the presence of the latex and a single amount copolymerizable therewith The inventors have found that the object of the present invention can be achieved by suspension polymerization of a mixture with the body, and have completed the present invention.

That is, the gist of the present invention is to produce a vinyl chloride polymer latex by an emulsion polymerization method using a fatty acid ammonium as an emulsifier or a fine suspension polymerization method when producing a vinyl chloride resin, and to produce a vinyl chloride polymer latex of 60 mesh or more. The particles are removed and the hydrogen ion concentration (pH) is adjusted to a range of 8.5 to 10, and in the presence of this latex, suspension polymerization of vinyl chloride or a mixture of vinyl chloride and a monomer copolymerizable therewith is carried out. It is a method for producing a vinyl chloride resin, which is characterized by that.

The present invention is described in detail below.

Monomers to which the method of the present invention can be applied include vinyl chloride alone and a combination of vinyl chloride and one or more vinyl-based monomers copolymerizable with vinyl chloride. Examples of the vinyl-based monomer here include vinyl acetate, styrene,
Acrylonitrile, acrylic acid ester, methacrylic acid ester, ethylene and other oil-soluble monomers; acrylic acid, methacrylic acid, maleic acid, crotonic acid and other water-soluble monomers; sodium acrylate, sodium fumarate, calcium acrylate, etc. Inorganic salts of vinyl monomers of Further, as the above-mentioned monomer, a vinyl-based monomer having a polyfunctional group copolymerizable with vinyl chloride, such as divinylbenzene, diallyl phthalate, diallyl malate or the like can be applied. The vinyl-based monomer having these polyfunctional groups provides a polymer having a crosslinked structure.

In order to effectively achieve the present invention, it is first necessary to carry out emulsion polymerization or fine suspension polymerization. A desired monomer selected from vinyl chloride alone or vinyl chloride and the above monomer group, respectively, and water, a fatty acid ammonium as an emulsifier and a water-soluble initiator or an oil-soluble initiator are placed in a reactor,
Polymerization is carried out after replacement with an inert gas.

The emulsifier used in the emulsion polymerization needs to be fatty acid ammonium and is usually used at pH 10 or higher. The amount of emulsifier is preferably 2.0 parts by weight or less per 100 parts by weight of the monomer.

Further, as the water-soluble initiator, hydrogen peroxide, potassium persulfate, ammonium persulfate or the like is used. As the oil-soluble polymerization initiator, an initiator that generates a free radical such as benzoyl peroxide, lauroyl peroxide, and di-tert-butyl peroxide is used. Furthermore, an oxidation-reduction system (redox) initiator can also be used.

After polymerizing up to 80% or more by the emulsion polymerization method or the fine suspension polymerization method by the above method, the coarse particles of 60 mesh or more are removed from the obtained latex, and the mixture is heated and degassed to adjust the pH.
Control to 8.5-10. As a method for adjusting the pH, there are a method of deammonification by heating, a method of acid treatment and the like. Among them, the method of acid treatment is most preferable.

Part or all of the latex and vinyl chloride alone or each of vinyl chloride and a desired monomer selected from the above-mentioned monomer group, and water, a suspending agent and an oil-soluble polymerization initiator are placed in a reactor, After replacement with an inert gas, suspension polymerization is carried out.

In the suspension polymerization, generally used suspending agents can be used, and examples thereof include various saponified products of polyvinyl acetate (polyvinyl alcohol), various water-soluble cellulose derivatives, maleic acid copolymers, gelatin, and the like. These may be used alone or in combination of two or more.
Further, these suspending agents may be used in combination with a kind of surfactant. As the oil-soluble polymerization initiator, an initiator that generates a free radical such as benzoyl peroxide, lauroyl peroxide, di-tert-butyl peroxide, and 2,2′-azobisisobutylnitrile is used. Further, the particle size can be controlled by the amounts of the suspending agent and water at this time. That is, the larger the amount of suspending agent and water, the smaller the particle size.

As described above, the method of the present invention is characterized by combining the emulsion polymerization method or the fine suspension polymerization method and the suspension polymerization method, but the polymerization conditions of the emulsion polymerization method and the suspension polymerization method may be arbitrarily changed. You can For example, the polymerization temperature may be different, or the polymerization degree of the polymer obtained by the emulsion polymerization method and the polymerization degree of the polymer obtained by the suspension polymerization method may be different. It is also possible to continue the polymerization while adding monomers stepwise or continuously to the reaction system during the polymerization by both polymerization methods. In the case of producing a copolymer, the polymerization by emulsion polymerization method and the suspension polymerization method may be carried out by combining different monomer compositions.

"Action" The polymer obtained by the method of the present invention is different from a simple mixture of fine particles produced by an emulsion polymerization method or a fine suspension polymerization method and coarse particles produced by a suspension polymerization method. It also has various characteristics.

In the method of the present invention, when the polymerization is carried out by an emulsion polymerization method using ammonium fatty acid as an emulsifier, fine particles having an ordinary diameter of 2 microns or less are obtained according to an ordinary reaction mechanism. Similarly, fine suspension polymerization yields fine particles of 2 microns or less. By adjusting the pH of the latex containing the fine particles, the action of the fatty acid ammonium as an emulsifier is eliminated and the latex is aggregated. The polymer produced in the subsequent suspension polymerization step wraps the aggregated particles,
The size is 20-500 microns (average particle size about 150 microns) as obtained by suspension polymerization. Therefore, after the reaction is completed, salting out like a usual emulsion polymerization method is not required,
And dehydration, washing and drying can be easily carried out as in the usual suspension polymerization method.

"Examples" Next, embodiments of the present invention will be described in detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

Example 1 Water 1000 cc Vinyl chloride 5.00 g Ammonyl myristate 0.3 g (added as an aqueous solution of 5 mol times excess as ammonia) 0.3 g potassium persulfate 0.3 g Sodium bisulfite 0.3 g were added to a 3 liter capacity autoclave with a stirrer and replaced with nitrogen After carrying out, emulsion polymerization was carried out at 58 ° C. for 5 hours under stirring at 200 rpm, and then unreacted vinyl chloride was separated by degassing operation. The polymerization rate of the initially charged monomer is 90%, the particle size is 0.2 micron and the solid content is 30.
% Lattex. Since coarse particles were contained in this latex, it was 100 mesh.

After heating the latex to 60 ° C and adjusting the pH to 8.5 with hydrochloric acid, the latex was controlled at 30 ° C to obtain a solid content of 2
It was diluted with water to 5% and 30 ml of 2% aqueous polyvinyl alcohol solution was added. The particle size at this time was an average of 100 μm as measured by the centrifugal sedimentation method.

Subsequently, using this latex, 300 g of water, 1000 g of latex, 300 g of vinyl chloride monomer 300 g, 2% solution of polyvinyl alcohol, 10 g of lauroyl peroxide were added to 3 liters of a stainless steel autoclave equipped with a stirrer, and suspension polymerization was carried out at 58 ° C. for 8 hours. After completion of the polymerization reaction, a polyvinyl chloride resin was obtained by washing with vinyl chloride, washing, dehydrating and drying. At this time, the total amount of polyvinyl chloride was 500 g.

There was almost no adhesion of the stainless steel autoclave. The average degree of polymerization of the obtained polyvinyl chloride was 1050, the average particle size was 150 μ, and the particle size distribution was as shown in Table 1 below.

Next, 3 parts by weight of dibutyl tin malate was added to 100 parts by weight of this polyvinyl chloride, and the mixture was kneaded with a heating roll, then 180
As a result of testing the thermal stability in a gear oven at 0 ° C., the polymer obtained in this example was colored light yellow in 100 minutes, and its coloring degree was almost the same as that of the polymer prepared by the commercial suspension polymerization method. ,
It showed much better thermal stability at 40 minutes than the similarly colored polymer by the commercial emulsification method.

The gelation time of the same composition as above was measured by Brabender Plastograph at 170 ° C. and found to be 80 seconds, which was compared with that of a polymer having an average degree of polymerization of 1050 obtained by the suspension polymerization method. The gel time was 150 seconds. This result indicates that the processability of the polymer obtained in the present invention is far superior to that of the polymer obtained by the suspension polymerization method.

Comparative Example 1 As a comparative example, suspension polymerization was carried out without adjusting the hydrogen ion concentration (pH).

After passing the latex obtained in Example 1 through 100 mesh, it was diluted with water to a solid content of 25% without adjusting the pH,
30 ml of 2% aqueous polyvinyl alcohol solution was added, and using the latex, water 300 g latex 1000 g vinyl chloride monomer 300 g polyvinyl alcohol 2% liquid 10 g lauroyl peroxide 2.1 g were added to a 3 l stainless steel autoclave equipped with a stirrer, and the mixture was heated at 58 ° C. for 8 hours. Suspension polymerization was carried out for an hour. After the completion of the polymerization reaction, many substances were attached inside the autoclave, and the wastewater became cloudy, and the amount of polyvinyl chloride resin in the wastewater was 30 g. The obtained product polyvinyl chloride resin amount was 400 g, and the average particle size was 300 μ, which was very coarse.

The particle size distribution is shown in Table 1'below.

Example 2 Water 1000cc Lauroyl peroxide 9g Ammonium myristate 6g Lauryl alcohol 3g was added to a 3L capacity autoclave with a stirrer, then the autoclave was degassed and vinyl chloride 6 was added.
00 g was added and kept at 35 ° C. with stirring. After uniformly stirring, the mixture was transferred to a 3 l autoclave with a stirrer, which had been degassed in advance while dispersing to a desired droplet size using an emulsifier. After the transfer of the dispersion liquid was completed, the temperature of the reaction tank was raised to 58 ° C. to carry out fine suspension polymerization. Product is particle size
The latex was 0.4 micron and 32% solids. Since coarse particles were contained in this latex, 100 mesh was used. The latex was heated to 60 ° C., adjusted to pH 8.5 to 10 with hydrochloric acid, diluted with water to a solid content of 25%, 32 ml of a 2% polyvinyl alcohol aqueous solution was added, and the stirring was separately prepared under the temperature condition of 30 ° C. 50 with a machined container
Hydrochloric acid was gradually added with stirring at 0 rpm to adjust the pH to 8.9 and to aggregate. The particle size distribution of this agglomerate was 100 when measured by a centrifugal sedimentation method and a particle size distribution analyzer.
It was micron.

Subsequently, using this latex, 300 g of water, 1000 g of agglomerated lattex, 300 g of vinyl chloride monomer, 300 g of polyvinyl alcohol 2% solution, 10 g of lauroyl peroxide were added to a 3-liter stainless steel autoclave equipped with a stirrer, and suspension polymerization was carried out at 58 ° C. for 8 hours. After completion of the polymerization reaction, a polyvinyl chloride resin was obtained by washing with vinyl chloride, washing, dehydrating and drying. At this time, the total amount of polyvinyl chloride resin was 500 g. There was almost no adhesion of the stainless steel autoclave. The obtained polyvinyl chloride has an average degree of polymerization of 1050 and an average particle size of 150 μm.
Met.

The following particle size distribution is shown in Table 2 as in Example 1.

Next, in the same manner as in Example 1, 3 parts by weight of dibutyltin malate was added to 100 parts by weight of this polyvinyl chloride, the mixture was kneaded with a heating roll, and then the thermal stability was tested in a gear oven at 180 ° C. The polymer obtained in 1. was colored light yellow in 100 minutes, and the degree of coloring was almost the same as that of the polymer prepared by the suspension polymerization method on the market. And showed much better thermal stability.

Further, the gelation time of the same composition as above was measured by Brabender Plastograph at 170 ° C. and found to be 85 seconds. The gelation time of a polymer having an average degree of polymerization of 1050 obtained by a commercially available suspension polymerization method was compared. The gel time was 150 seconds. This result indicates that the processability of the polymer obtained in the present invention is far superior to that of the polymer obtained by the suspension polymerization method.

“Effect” 1 In the conventional technique, the particle size distribution was not constant and was wide, but according to the present invention, the particle size distribution became sharp,
Easy to control.

2 The thermal stability of the polymer obtained in the present invention is as excellent as that of the polymer obtained by the usual suspension polymerization method,
It is far superior to the polymer obtained by the usual emulsion polymerization method.

3 Further, the polymer obtained by the present invention has the same excellent processability and gelation property as those obtained by the usual emulsion polymerization method, and is superior to the polymer obtained by the usual suspension polymerization method. It has much better processability and gelation properties.

Claims (1)

[Claims] 1. In producing a vinyl chloride resin, a vinyl chloride polymer latex is produced by an emulsion polymerization method or a fine suspension polymerization method using a fatty acid ammonium as an emulsifier, and coarse particles of 60 mesh or more are removed. The method is characterized in that the hydrogen ion concentration (pH) is adjusted to a range of 8.5 to 10 and suspension polymerization of vinyl chloride or a mixture of vinyl chloride and a monomer copolymerizable therewith in the presence of this latex is carried out. Manufacturing method of vinyl chloride resin.