JPH0542446B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing vinyl chloride resin, and more specifically, the present invention relates to a method for producing vinyl chloride resin, and more specifically, a vinyl chloride resin obtained by graft copolymerizing vinyl chloride onto an acrylic polymer latex having a stable particle size is produced by suspension polymerization. The present invention relates to a method of manufacturing the same. [Prior Art] Vinyl chloride resin has excellent physical and mechanical properties, and therefore has many uses such as hard, semi-hard, and soft. When vinyl chloride homopolymer is used for hard materials, it has the disadvantage of poor impact resistance and weather resistance. As a method for improving these drawbacks, there is a method of blending various elastomers with vinyl chloride homopolymer. According to this method, impact resistance can be improved, but it has the disadvantage of decreasing weather resistance and flexural modulus. Furthermore, vinyl chloride graft copolymers obtained by graft copolymerizing vinyl chloride onto acrylic polymers are known to have excellent impact resistance, weather resistance, and flexural modulus. One way to obtain this vinyl chloride graft copolymer is to graft copolymerize vinyl chloride onto acrylic rubber, but this method involves a step of cutting the rubber into small pieces, and then swelling the cut rubber with vinyl chloride. Requires a dissolving process,
Therefore, there is a problem in workability, so it is disadvantageous for industrial implementation. As a method for solving the above problem, there is a method in which vinyl chloride is graft copolymerized onto an acrylic polymer latex. This method improves workability, but since the polymerization method is suspension polymerization in the presence of an emulsifier contained in the acrylic polymer latex, it requires a large amount of dispersant. Variations in particle size tend to occur, making it impossible to obtain a product with stable particle size. [Problems to be Solved by the Invention] The present invention relates to an emulsion-suspension polymerization method, that is, a method in which an acrylic polymer latex obtained by emulsion polymerization is graft-copolymerized with vinyl chloride by a suspension polymerization method. , the purpose is to obtain a product with stable particle size. [Means for Solving the Problems] As a result of extensive research in order to achieve the above object, the present inventors coagulated an acrylic polymer latex in a graft copolymerization reaction tank, and then coagulated vinyl chloride. It has been discovered that a product with stable particle size can be obtained by adding the above particles and carrying out graft copolymerization using a suspension polymerization method, leading to the present invention. That is, in the present invention, when producing a graft copolymer by graft copolymerizing vinyl chloride onto an acrylic polymer, the acrylic polymer latex is placed in a graft copolymerization reaction tank according to the following conditions in the periodic table.
A vinyl chloride resin with stable particle size is produced by graft copolymerizing vinyl chloride using a suspension polymerization method after coagulating with one or more selected from the group consisting of metal salts and ammonium salts. This is the way to do it. The acrylic polymer latex used in the present invention is a copolymer latex mainly composed of alkyl acrylate and/or alkyl methacrylate, and containing other copolymerizable monomers as necessary. Examples of alkyl acrylate and alkyl methacrylate include methyl acrylate,
Ethyl acrylate, n-propyl acrylate, iso-butyl acrylate, n-butyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, n-decyl acrylate, n-dodecyl acrylate, lauryl acrylate and their methacrylates. can give. In addition, copolymerizable monomers include monofunctional monomers such as olefins such as ethylene, propylene, and hexene, aromatic vinyls such as styrene, α-methylstyrene, and vinyltoluene, and acrylonitrile and methacrylonitrile. Unsaturated nitriles, vinyl esters such as vinyl acetate and vinyl propionate, vinyl ethers such as butyl vinyl ether and lauryl vinyl ether, polyfunctional monomers such as ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate,
Acrylates of mono- or polyalkylene glycols such as ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, 1,3-propylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate Alternatively, di- or triallyl compounds such as methacrylates, diallyl phthalate, diallyl maleate, diallyl fumarate, diallyl succinate, and triallyl isocyanurate, and divinyl compounds such as divinylbenzene and butadiene may be mentioned. The alkyl acrylate, alkyl methacrylate, and copolymerizable monomers may be used alone or in combination of two or more to obtain a latex. The amount of acrylic polymer latex added is also determined depending on the intended use of the final product. The acrylic polymer latex used in the present invention is obtained by emulsion polymerization, and the average particle size of the latex is preferably about 0.01 to 10 μm. To obtain an acrylic polymer latex by a general emulsion polymerization method, for example, pure water, an anionic emulsifier,
A water-soluble polymerization initiator is charged, the air inside the can is removed, then monomers copolymerizable with alkyl acrylate and/or alkyl methacrylate are charged, and after emulsification, the inside of the can is heated with a jacket to initiate the reaction. Let it start. The reaction is exothermic;
Control the internal temperature from the jacket as necessary. After the reaction is completed, unreacted monomers are removed from the can to obtain an acrylic polymer latex. The method of charging into the polymerization reactor is not limited.
Further, if necessary, a latex particle size adjusting agent, a catalyst decomposition accelerator, etc. may be added to control the reaction. The acrylic polymer latex is made by the above method.
It is possible to manufacture up to a concentration of 50wt%, but due to manufacturing
For handling purposes, a concentration of 10 to 30 wt% is advantageous. Coagulants for the acrylic polymer latex used in the present invention include metal salts and ammonium salts of groups 1 and 2 of the periodic table. Examples include sodium chloride, sodium nitrate, sodium acetate, sodium sulfate, sodium phosphate, potassium chloride, potassium nitrate, potassium acetate, potassium sulfate, potassium phosphate, calcium chloride, calcium nitrate, calcium acetate, calcium sulfate, calcium phosphate, chloride. Magnesium, magnesium nitrate, magnesium acetate, magnesium sulfate,
Metal salts such as magnesium phosphate, aluminum chloride, aluminum nitrate, aluminum acetate, aluminum sulfate, aluminum phosphate, ammonium chloride, ammonium nitrate, ammonium acetate,
Examples include ammonium salts such as ammonium sulfate and ammonium phosphate. It is desirable to use the coagulant in an optimum amount that can stably carry out suspension polymerization without impeding the effect of the dispersant used. If the pH of the suspension decreases, it may be neutralized with a basic substance such as sodium hydroxide, calcium hydroxide, or aqueous ammonia to prevent the effect of the dispersant from decreasing. do not have. When carrying out an aqueous suspension polymerization method, the amount of water used is 1 to 5 times, preferably 1 to 3 times, the total amount of the acrylic polymer as the backbone polymer and the vinyl chloride monomer. To obtain a graft copolymer resin by the suspension polymerization method of the present invention, for example, pure water, a coagulant, a radical polymerization initiator, and, if necessary, a degree of polymerization regulator are placed in a jacketed polymerization reactor, and the mixture is stirred. An acrylic polymer latex is placed at the bottom and allowed to solidify, then the air inside the can is removed, a dispersant such as hydroxypropyl methyl cellulose is added, and then vinyl chloride is charged, along with other vinyl compounds as necessary. . Then heat the inside of the can with a jacket,
Start graft copolymerization. Graft copolymerization is an exothermic reaction, and the internal temperature is controlled by the jacket as necessary. After the reaction is completed, unreacted vinyl chloride is removed into the can to obtain a slurry of graft copolymer resin. The slurry is dehydrated and dried in a conventional manner to obtain a graft copolymer resin. In carrying out the present invention, it is advantageous to carry out the graft copolymerization by a radical polymerization method, and the radical polymerization initiators used for this purpose include lauroyl peroxide, tert-butyl peroxypivalate, diisopropyl peroxydi carbonate, organic peroxides such as dioctyl peroxydicarbonate, 2,2'-azobisisobutyronitrile, 2,2'-azobis-2,
Examples include oil-soluble polymerization initiators such as azo compounds such as 4-dimethylvaleronitrile, and water-soluble polymerization initiators such as potassium persulfate and ammonium persulfate. The amount of these polymerization initiators used is
The amount is preferably 0.005 to 1.0 parts by weight per 100 parts by weight. Dispersants include methylcellulose, ethylcellulose, hydroxypropylmethylcellulose, hydroxyethylcellulose, polyvinyl alcohol and partially saponified products thereof, gelatin, polyvinylpyrrolidone, starch, maleic anhydride.
Examples include styrene copolymers, which may be used alone or in combination. The amount added is 0.01 to 1.0 parts by weight per 100 parts by weight of vinyl chloride. Furthermore, in the present invention, a chain transfer agent used in conventional methods for polymerizing vinyl monomers may be added in an amount of 0.001 to 10 parts by weight per 100 parts by weight of vinyl chloride. The graft copolymer resin obtained by the method of the present invention has a stable average particle size of 90 to 120 μm and is very easy to handle during processing. The graft copolymer resin obtained by the method of the present invention contains the usual stabilizers, lubricants, processing aids, antioxidants, fillers, ultraviolet absorbers, pigments, etc. used in the molding process of vinyl chloride resin. As a result, it can be subjected to normal molding processing, and is suitably used for building materials etc. by taking advantage of its excellent impact resistance and weather resistance. [Example] Hereinafter, the present invention will be specifically explained with reference to Examples. Reference Example 1 (Manufacturing example of acrylic latex) 2000 kg of deionized water, 7.0 kg of anionic emulsifier, 0.7 kg of ammonium persulfate, and 700 kg of n-butyl acrylate were placed in a polymerization machine with an internal volume of 5 m ³ equipped with a stirring blade.
After adding 35 kg of 1,3-butylene glycol dimethacrylate and replacing the internal air with nitrogen, the
Polymerization was carried out at °C. Fifteen hours after the start of polymerization, the internal temperature began to rise rapidly, so heat was removed through a jacket and a backflow condenser, and the reaction was continued for another 10 hours, then the polymerization reaction was stopped. The concentration of the obtained latex was 25%, and the average particle size was 0.07 μm. Example 1 In a polymerization machine with an internal volume of 7 m ³ equipped with a stirring blade, 2700 kg of deionized water, 1.5 kg of NaCl, 1.0 kg of partially saponified polyvinyl alcohol, 1.0 kg of methyl cellulose,
After adding 0.45 kg of 2,2'-azobisisobutyronitrile and removing the air inside with a vacuum pump,
840 kg of acrylic polymer latex (solid content 210 kg) with the composition shown in the table at a concentration of 25% was charged under stirring.
The acrylic polymer latex was solidified. Thereafter, 1290 kg of vinyl chloride was charged and polymerization was carried out at 60°C. 11 hours after the start of polymerization, the internal pressure of the polymerization machine increased.
When the weight decreased to 6.5 Kg/cm ² , the polymerization reaction was stopped. After removing unreacted vinyl chloride monomer,
When the slurry was dehydrated and dried using a conventional method, 1250 kg of white powder particles were obtained. The average particle size of this white powder was 113 μm, and the particle size distribution was also narrow and stable. Example-2 A polymerization machine with an internal volume of 7 m ³ equipped with a stirring blade was charged with 2700 kg of deionized water, 0.9 kg of Al ₂ (SO ₄ ) ₃ , 0.75 kg of partially saponified polyvinyl alcohol, and methyl cellulose.
0.75Kg, 2,2'-azobisisobutyronitrile
After adding 0.075 kg of 2,2'-azobis-2,4-dimethylvaleronitrile and 0.24 kg of 2,2'-azobis-2,4-dimethylvaleronitrile and removing the air inside with a vacuum pump, the concentration of the composition shown in Table 1 was 15.
% acrylic polymer latex 600Kg (solid content
90Kg) was charged under stirring and allowed to solidify. Thereafter, 1410 kg of vinyl chloride was charged and polymerization was carried out at 57°C. 10 hours after the start of polymerization, the internal pressure of the polymerization machine was 6.5.
The polymerization reaction was stopped when the amount decreased to Kg/cm ² . After removing unreacted vinyl chloride, the slurry was dehydrated and dried using a conventional method, and 1200 particles of white powder were obtained.
Kg was obtained. The average particle size of this white powder was 108 μm, and the particle size distribution was also narrow and stable. Comparative Example 1 Polymerization was carried out in the same manner as in Example-1, except that 2.25 kg of partially saponified polyvinyl alcohol and 2.25 kg of methyl cellulose were added, and NaCl was not charged, to produce 1100 kg of white powder particles. Obtained. The average particle size of this white powder is as large as 255 μm.
Moreover, the particle size distribution was wide. Comparative Example 2 Polymerization was carried out in the same manner as in Comparative Example 1, except that 2.325 kg of partially saponified polyvinyl alcohol and 2.325 kg of methyl cellulose were used in Comparative Example 1 to obtain 1220 kg of white powder particles. The average particle size of this white powder was 76 μm, and the particle size distribution was wide. Comparative Example 3 In Example-2, 1.95Kg of partially saponified polyvinyl alcohol and 1.95Kg of methyl cellulose
Polymerization was carried out in the same manner as in Example 2, except that Al ₂ (SO ₄ ) ₃ was not charged, and 1190 kg of white powder particles were obtained. The average particle size of this white powder was 189 μm, and the particle size distribution was wide. Comparative Example 4 In Comparative Example-3, 2.025 kg of partially saponified polyvinyl alcohol and 2.025 kg of methyl cellulose were used.
Polymerization was carried out in the same manner as in Comparative Example 3, except that 1200 kg of white powder particles were obtained. The average particle size of this white powder was 80 μm, and the particle size distribution was wide. The results of the above Examples and Comparative Examples are summarized in Table 1. The particle size distribution is determined by stacking JIS standard sieves in the order of 60, 80, 100, 150, 200, 270 mesh and a saucer from the top, placing 50g of sample on the top sieve, and placing it on a sieve shaker for 15 minutes. After applying vibration, the proportion of resin present on each sieve and saucer was determined and expressed in weight %. In addition, the average particle size is determined by plotting the cumulative total of the remaining percentage of each mesh on the horizontal axis of the regularity probability table and the mesh opening (μm) of each mesh on the vertical axis.
The cumulative total is expressed in 50% eye opening (μm).

〔Effect of the invention〕

In the method of the present invention, since the acrylic polymer latex is coagulated once, the particle size distribution of the obtained vinyl chloride graft copolymer particles is sharp, and the average particle size is also sufficiently large.
In good condition. On the other hand, when solidification is not performed, a large amount of dispersant is required, and as seen in the comparative example, even a slight difference in the dispersant causes extreme changes in the particle size distribution and average particle diameter.

Claims (1)

[Claims] 1. When producing a graft copolymer by graft copolymerizing vinyl chloride onto an acrylic polymer, the acrylic polymer latex is mixed with metal salts of groups 1 and 2 of the periodic table in a reaction tank in which the graft copolymerization is carried out. 1 selected from the group consisting of ammonium salts
A method for producing a vinyl chloride resin, which comprises coagulating it with at least one salt, and then graft copolymerizing vinyl chloride by a suspension polymerization method.