JPH0576965B2 - - Google Patents

Description

[Detailed description of the invention]

"Industrial Application Field" The present invention relates to a method for producing vinyl chloride resin. More specifically, vinyl chloride resins having desirable properties such as vinyl chloride polymers obtained by emulsion polymerization can be produced in preferred forms such as polymers obtained by suspension polymerization. The present invention relates to a method for producing vinyl chloride resin. "Prior Art" Vinyl chloride polymers produced by emulsion polymerization have fine polymer particles and excellent processability. On the other hand, when producing vinyl chloride polymers by suspension polymerization, the particles produced are coarse, so dehydration, washing, drying, etc. after the polymerization reaction is easy, and the thermal stability of the obtained polymer is It has excellent electrical properties, transparency, weather resistance, etc., and is easy to handle during processing. Attempts have been made to produce vinyl chloride resins having desirable properties such as vinyl chloride polymers obtained by emulsion polymerization in a desirable form such as polymers obtained by suspension polymerization. It is publicly known as described in Publication No. 45-30834. This method uses 5 to 90% of the total amount of polymer to be finally obtained.
% by emulsion polymerization method, then water, a suspending agent and an oil-soluble polymerization initiator are added to the reaction system, and the remaining polymerization is produced by suspension polymerization method. "Problems to be Solved by the Invention" This method leaves coarse particles as by-products in the latex obtained by emulsion polymerization as they are, and does not control latex agglomerated particles at the latex stage. Next, the particle size distribution of the vinyl chloride resin produced by suspension polymerization is widely inconsistent and has a large variation, which causes so-called lumps and hard eyes to occur in the molded product, making it difficult to put it into practical use. There were many things I didn't get. Furthermore, during suspension polymerization, polymer scale was significantly attached to the can wall. "Means for Solving the Problems" The present inventors have made use of the advantages of the above-mentioned prior art, in other words, to produce vinyl chloride having various desirable properties such as vinyl chloride polymers obtained by emulsion polymerization. A method for producing a vinyl chloride resin that can be obtained in a preferred form such as a polymer obtained by suspension polymerization, has less adhesion to can walls, is easy to control particle size, and has a sharp particle size distribution. We conducted extensive research to develop this. As a result, when carrying out suspension polymerization, by pre-existing an electrolyte in the reaction system and adding a vinyl chloride polymer latex from which coarse particles have been removed, which has been separately produced by an emulsion polymerization method or a fine suspension polymerization method, the present invention can be carried out. The inventors discovered that the object could be achieved and completed the present invention. That is, the gist of the present invention is to produce a vinyl chloride resin by suspension polymerizing vinyl chloride or a mixture of vinyl chloride and a monomer copolymerizable therewith in an aqueous medium in the presence of an oil-soluble polymerization initiator. In the method, an electrolyte is present in the suspension polymerization reaction system, and a vinyl chloride polymer latex produced separately by an emulsion polymerization method or a fine suspension polymerization method is obtained by removing coarse particles of 60 mesh or more. A method for producing a vinyl chloride resin, characterized by adding the following: The present invention will be explained in detail below. Monomers to which the method of the present invention can be applied include vinyl chloride alone, and combinations of vinyl chloride and one or more vinyl monomers that can be copolymerized with vinyl chloride. Examples of vinyl monomers mentioned here include vinyl acetate, styrene, acrylonitrile,
Oil-soluble monomers such as acrylic acid ester, methacrylic acid ester, ethylene; water-soluble monomers such as acrylic acid, methacrylic acid, maleic acid, crotonic acid; vinyl such as sodium acrylate, sodium fumarate, calcium acrylate, etc. Examples include inorganic salts of monomers. Moreover, as the above-mentioned monomer, a vinyl monomer having a polyfunctional group copolymerizable with vinyl chloride, such as divinylbenzene, diallyl phthalate, diallyl maleate, etc., can be used. These vinyl monomers having polyfunctional groups yield polymers having a crosslinked structure. In order to effectively achieve the present invention, it is first necessary to carry out emulsion polymerization or microsuspension polymerization. Vinyl chloride alone or vinyl chloride and each desired monomer selected from the above monomer group, as well as water, an emulsifier, a water-soluble initiator or an oil-soluble initiator, and optionally a PH regulator are added to a reactor. After replacing with inert gas, polymerization is carried out. As the emulsifier that can be used in the emulsion polymerization, water-soluble emulsifiers are suitable, and anionic emulsifiers are particularly good.
The content is preferably 2.0 parts by weight or less per 100 parts by weight. Further, as the water-soluble polymerization initiator, hydrogen peroxide, potassium persulfate, ammonium persulfate, etc. are used. As the oil-soluble polymerization initiator, an initiator that generates free radicals such as benzoyl peroxide, lauroyl peroxide, di-tertiary butyl peroxide, etc. is used. Additionally, oxidation-reduction (redox) initiators can also be used. After polymerizing to 80% or more by emulsion polymerization or fine suspension polymerization using the above method, coarse particles of 60 mesh or more are removed from the resulting latex. Next, vinyl chloride alone or vinyl chloride and each of the desired monomers selected from the monomer group mentioned above, water, a suspending agent, an oil-soluble polymerization initiator, and an electrolyte are placed in a reactor, and the atmosphere is replaced with an inert gas. After carrying out these steps, the vinyl chloride polymer latex described above is added continuously or intermittently to the suspension polymerization reaction system to carry out suspension polymerization. Generally used suspending agents can be used for suspension polymerization, such as various saponified products of polyvinyl acetate (polyvinyl alcohol), various water-soluble cellulose derivatives, maleic acid copolymers, gelatin, etc. These can be used alone or in combination of two or more. Furthermore, these suspending agents and certain surfactants can also be used in combination. Further, the particle size can be controlled by adjusting the amount of suspending agent and water at this time. That is, as the amount of suspending agent and water increases, the particle size becomes smaller. As the oil-soluble polymerization initiator, those mentioned above can be used. Furthermore, water-soluble salts can be used as the electrolyte added to coagulate the added latex. These salts are on the periodic table,
The salts, type and quantity are selected according to the quality objective of the resin to be produced. The type and amount of salts are determined by preliminary studies, but they must be at least in an amount that will allow the added latex to coagulate during the polymerization period. Examples of these salts include hydrochloric acid, sulfuric acid, calcium chloride, calcium acetate, aluminum chloride, magnesium chloride, and the like. It is desirable that the addition of the vinyl chloride polymer latex be completed when the reaction rate of suspension polymerization is within 30%. As mentioned above, the method of the present invention is characterized by a combination of emulsion polymerization method or fine suspension polymerization method and suspension polymerization method, but the polymerization conditions for each of emulsion polymerization method and suspension polymerization method can be changed arbitrarily. . For example, the polymerization temperature may be different, and the degree of polymerization of a polymer obtained by emulsion polymerization may be different from that of a polymer obtained by suspension polymerization. Further, during the polymerization by both polymerization methods, the polymerization can be continued while adding monomers to the reaction system stepwise or continuously. Furthermore, when producing a copolymer, emulsion polymerization and suspension polymerization may be carried out using combinations of different monomer compositions. "Operation" The polymer obtained by the method of the present invention is different from a mere mixture of fine particles produced by emulsion polymerization method or fine suspension polymerization method and coarse particles produced by suspension polymerization method. It also has the favorable characteristics brought about by the polymerization method. First, when polymerization is carried out by the emulsion polymerization method, fine particles of 2 microns or less are obtained according to the usual reaction mechanism of emulsion polymerization. Similarly, fine particles of 2 microns or less can be obtained using the fine suspension polymerization method. When these fine particles are added to a suspension polymerization reaction system containing an electrolyte, the fine particles aggregate together, and the polymer produced in the suspension polymerization process wraps them and has a diameter of 20 to 500 microns ( The average particle size is approximately 150 microns).
Therefore, after completion of the reaction, salting out as in conventional emulsion polymerization is not required, and dehydration, washing and drying can be easily carried out as in conventional suspension polymerization. "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 1000c.c. vinyl chloride 500g sodium lauryl sulfate 0.5g potassium persulfate 0.3g sodium bisulfite 0.3g sodium bicarbonate 0.4g were added to an autoclave with a capacity of 3 and equipped with a stirrer, and after replacing with nitrogen, the mixture was heated at 200 rpm.
After emulsion polymerization was carried out at 58° C. for 5 hours with stirring, unreacted vinyl chloride was separated by degassing. The polymerization rate of the initially charged monomer was 90%, and the latex had a particle size of 0.2 microns and a solid content of 30%. This latex contains coarse particles, so
I spent time in Metshiyu. Next, add 1400 g of water, 700 g of vinyl chloride monomer, 40 g of 2% polyvinyl alcohol solution, 2.1 g of lauroyl peroxide, and 10 g of calcium acetate to the stainless steel autoclave equipped with a stirrer in Step 3, and when the internal temperature reaches 58°C, add 400 g of the aforementioned latex at once. Time suspension polymerization was carried out. After the polymerization reaction was completed, the dechlorinated vinyl monomer was washed, dehydrated and dried to obtain a polyvinyl chloride resin. The total amount of polyvinyl chloride at this time was 700 g. There was almost no amount of adhesion in the stainless steel autoclave. The average degree of polymerization of the obtained polyvinyl chloride was 1050, the average particle size was 150μ, and the particle size distribution was as shown in Table 1 below.

[Table] Next, 3 parts by weight of dibutyltin malate was added to 100 parts by weight of this polyvinyl chloride, and after kneading with heated rolls, the thermal stability was tested in a gear oven at 180°C. The polymer obtained in this example was colored pale yellow in 90 minutes, and the degree of coloration was slightly inferior to that of a polymer produced by a commercially available suspension polymerization method, but it was comparable to a polymer produced by a commercially available emulsion method that was similarly colored in 40 minutes. showed much better thermal stability in comparison. Furthermore, when the gelation time of the same formulation as above was measured using a Brabender plastograph at 170°C, it was 80 seconds, which was compared to the average degree of polymerization of 1050 obtained by a commercially available suspension polymerization method. The gelation time of the polymer was 150 seconds. This result shows that the processability of the polymer obtained according to the present invention is far superior to that of the polymer obtained by suspension polymerization. Comparative Example 1 As a comparative example, suspension polymerization was carried out without using an electrolyte. Add 1400 g of water, 700 g of vinyl chloride monomer, 40 g of 2% polyvinyl alcohol solution, and 2.1 g of lauroyl peroxide to the stirrer-equipped autoclave in Step 3. After the internal temperature reached 58°C, add 400 g of the latex passed through the 100 mesh obtained in Example 1.
was added all at once, and suspension polymerization was carried out for 8 hours. After the polymerization reaction was completed, there was a lot of adhesion inside the autoclave, and the wastewater became cloudy, and the amount of polyvinyl chloride resin in the wastewater was 20%.
It was hot at g. The amount of polyvinyl chloride resin obtained was 600 g, the average particle size was very coarse, 300 μm, and the particle size distribution was wide as shown in Table 1' below.

[Table] As shown above, unless an electrolyte is used, the wastewater becomes cloudy and good polyvinyl chloride resin cannot be obtained. Example 2 1400 g of water, 700 g of vinyl chloride monomer, 40 g of 2% methyl cellulose solution, 2.1 g of lauroyl peroxide, and 10 g of calcium acetate were added to the stainless steel autoclave with a stirrer in Example 2. After the internal temperature reached 58°C, a latex was obtained in the same manner as in Example 1. Add 400g at once,
Suspension polymerization was carried out for 8 hours. After the polymerization reaction was completed, the dechlorinated vinyl monomer was washed, dehydrated and dried to obtain a polyvinyl chloride resin. There was almost no amount of adhesion on the stainless steel autoclave. The average degree of polymerization of the obtained polyvinyl chloride was 1050, and the average particle size was 150μ.
The particle size distribution was as shown in Table 2 below.

[Table] Next, as in Example 1, this vinyl chloride resin 100
After adding 3 parts by weight of dibutyltin malate to the parts by weight and kneading with a heating roll, the thermal stability was tested in a gear oven at 180°C. As a result, the polymer obtained in this example turned pale yellow in 85 minutes. It was colored, and the degree of coloration was almost the same as that of a commercially available suspension polymerization method, and it showed much better thermal stability in 40 minutes than a similarly colored commercially available emulsification polymer. In addition, when the gelation time of the same formulation as above was measured using a Brabender plastograph at 170°C, it was 75 seconds, compared to a polymer with an average degree of polymerization of 1050 obtained by a commercially available suspension polymerization method. The gelation time was 150 seconds. This result shows that the processability of the polymer obtained according to the present invention is far superior to that of the polymer obtained by suspension polymerization. Example 3 1400 g of water, 700 g of vinyl chloride monomer, 40 g of 2% polyvinyl alcohol solution, 2.1 g of lauroyl peroxide, and 10 g of calcium acetate were added to the stainless steel autoclave equipped with a stirrer in step 3, and after the internal temperature reached 58°C, the same procedure as in Example 1 was obtained. 400 g of latex was added over 1 hour, and suspension polymerization was carried out for 8 hours. After the polymerization reaction was completed, the dechlorinated vinyl monomer was washed, dehydrated and dried to obtain a polyvinyl chloride resin. At this time, the total amount of polyvinyl chloride resin was 700 g. There was almost no amount of adhesion on the stainless steel autoclave. The average degree of polymerization of the obtained polyvinyl chloride resin was 1050, the average particle size was 150μ, and the particle size distribution was as shown in Table 3 below.

[Table] Next, as in Example 1, this polyvinyl chloride 100
After adding 3 parts by weight of dibutyltin malate to the parts by weight and kneading with a heating roll, the thermal stability was tested in a gear oven at 180°C. The polymer obtained in this example turned light yellow in 90 minutes. Although the degree of coloration was slightly inferior to that of the commercially available suspension polymerization method, it showed much better thermal stability in 40 minutes than the commercially available emulsion-based polymer, which was similarly colored. In addition, when the gelation time of the same formulation as above was measured using a Brabender plastograph at 170°C, it was 80 seconds, compared to a polymer with an average degree of polymerization of 1050 obtained by a commercially available suspension polymerization method. The gelation time was 150 seconds. This result shows that the processability of the polymers obtained according to the present invention is far superior to that of polymers obtained by suspension polymerization. Example 4 1000 c.c. of water, 9 g of lauroyl peroxide, 6 g of sodium lauryl sulfate, and 3 g of lauryl alcohol were added to a 3-volume autoclave with a stirrer, then the autoclave was degassed, 600 g of vinyl chloride was added, and the temperature was maintained at 35°C while stirring. did. After stirring uniformly, the mixture was dispersed into a desired droplet size using an emulsifier and transferred to a 3-equipped autoclave equipped with a stirrer, which had been previously degassed. After the transfer of the dispersion liquid was completed, the temperature of the reaction tank was raised to 58°C, and fine suspension polymerization was performed. Solid content 32 with particle size 0.4 micron
% latex. Since this latex contained coarse particles, it was used at 100 mesh. Next, 1400 g of water, 700 g of vinyl chloride monomer, 40 g of 2% polyvinyl alcohol solution, 2.1 g of lauroyl peroxide, and 10 g of calcium acetate were added to the stainless steel autoclave equipped with a stirrer in Step 3. After the internal temperature reached 58°C, 400 g of the latex described above was added at once. Suspension polymerization was carried out for 8 hours. After the polymerization reaction was completed, the dechlorinated vinyl monomer was washed, dehydrated and dried to obtain a polyvinyl chloride resin. The total amount of polyvinyl chloride resin at this time was 700 g. There was almost no amount of adhesion on the stainless steel autoclave. The average degree of polymerization of the obtained polyvinyl chloride was 1050, the average particle size was 150μ, and the particle size distribution was as shown in Table 4 below.

[Table] Next, 3 parts by weight of dibutyltin malate was added to 100 parts by weight of this polyvinyl chloride resin, and after kneading with heated rolls, the thermal stability was tested in a gear oven at 180°C. The polymer obtained in this example was colored pale yellow in 90 minutes, and the degree of coloration was slightly inferior to that of a polymer produced by a commercially available suspension polymerization method, but it was comparable to a polymer produced by a commercially available emulsion method that was similarly colored in 40 minutes. showed much better thermal stability in comparison. In addition, when the gelation of the same formulation as above was measured at 170℃ using a Brabender plastograph,
In comparison, the gelation time of a polymer with an average degree of polymerization of 1050 obtained by a commercially available suspension polymerization method was 150 seconds. This result shows that the processability of the polymer obtained according to the present invention is far superior to that of the polymer obtained by suspension polymerization. "Effects" 1 In the conventional technology, the particle size distribution was not constant and varied over a wide range, but with the present invention, the particle size distribution becomes sharp and can be easily controlled. 2. In the conventional technology, the deposition of polymer scale during suspension polymerization was significant, but in the present invention, it was reduced. 3. The thermal stability of the polymer obtained by the present invention is as good as that of a polymer obtained by a conventional suspension polymerization method. 4. The processability and gelation properties of the polymer obtained in the present invention are as good as those obtained by conventional emulsion polymerization methods.

Claims (1)

[Claims] 1. Vinyl chloride resin is obtained by suspension polymerizing vinyl chloride or a mixture of vinyl chloride and a monomer copolymerizable therewith in an aqueous medium in the presence of an oil-soluble polymerization initiator. In the manufacturing method, an electrolyte is present in the suspension polymerization reaction system, and coarse particles of 60 mesh or more are removed from the vinyl chloride polymer latex that is separately manufactured by an emulsion polymerization method or a fine suspension polymerization method. 1. A method for producing vinyl chloride resin, which comprises adding a polyvinyl chloride resin. 2. The method for producing a vinyl chloride resin according to claim 1, wherein the vinyl chloride polymer latex is added continuously or intermittently.