JPS6143608A - Preparation of vinyl chloride resin - Google Patents

Abstract

PURPOSE:To obtain vinyl chloride resin having stabilized particle size, by coagulating an acrylic polymer latex in a reaction tank with a metal salt, etc., adding vinyl chloride thereto, and graft copolymerizing the vinyl chloride with the latex by suspension polymerization. CONSTITUTION:One or more of a metal salt of Groups I -III in the periodic table, e.g. sodium chloride, and ammonium salt, e.g. ammonium chloride, as a coagulating agent in adequete amounts are added to an acrylic polymer latex, obtained by emulsion polymerization, and having preferably 0.01-10mu average particle diameter and 10-30wt% concentration to coagulate the latex. Vinyl chloride and if necessary a dispersing agent, e.g. hydroxypropyl methyl cellulsoe, etc. are added thereto, and the graft copolymerization is carried out using preferably a radical polymerization initiator, e.g. 2,2'-azobis-2,4-dimethylvaleronitrile, by the suspension polymerization method to give the aimed resin.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing vinyl chloride resin, and more specifically, to a vinyl chloride resin produced by graft copolymerizing vinyl chloride onto an acrylic polymer latex having a stable particle size. This invention relates to a method for producing resin by suspension polymerization.

[Conventional technology]

Vinyl chloride resin has excellent physical and mechanical properties, so it has many uses including hard, semi-hard, and soft.

If vinyl chloride homopolymer is used for hardness, i't
It has the disadvantage of being inferior in WI 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.

In addition, vinyl chloride graft copolymer obtained by graft copolymerizing vinyl chloride to acrylic polymer has impact resistance,
It is known for its weather resistance and flexural modulus.

As a method for obtaining this vinyl chloride graft copolymer, there is a method of graft copolymerizing vinyl chloride to acrylic rubber, but this method involves a step of cutting the rubber into small pieces,
Furthermore, a step of swelling or dissolving the cut rubber in vinyl chloride is required, which poses a problem in workability.
It is disadvantageous for industrial implementation.

As a method for solving the above problem, there is a method of graft copolymerizing vinyl chloride 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, and Variations in particle size tend to occur, making it impossible to obtain a product with stable particle size.

[Problem that the invention seeks to solve]

The present invention aims to obtain a product with stable particle size in an emulsion-suspension polymerization method, that is, in a method in which an acrylic polymer latex obtained by emulsion polymerization is graft-copolymerized with vinyl chloride by a suspension polymerization method. purpose.

[Failure to solve the problem]

As a result of extensive research in order to achieve the above object, the present inventors coagulated acrylic polymer latex in a graft copolymerization reaction tank, then added vinyl chloride,
It has been discovered that a product with stable particle size can be obtained by 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 prepared in a graft copolymerization reaction tank in accordance with 1, II, and 1 of the periodic table. A vinyl chloride resin with stable particle size is obtained by coagulating it with one or more selected from the group consisting of metal salts and ammonium salts, and then graft copolymerizing vinyl chloride by a suspension polymerization method. This is a method of manufacturing.

The acrylic polymer latex used in the present invention is a copolymer latex mainly composed of alkyl acrylate and/or alkyl methacrylate, and optionally containing other copolymerizable monomers.

Examples of the alkyl acrylate and alkyl methacrylate include methyl acrylate, ethyl acrylate, n-propyl acrylate, 1so-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.

Examples of copolymerizable heptamers include monofunctional monomers such as olefins such as ethylene, propylene, and hexene, aromatic vinyls such as styrene, α-methylstyrene, and vinyltoluene, and acrylonitrile and methacrylate trile. Vinyl esters such as unsaturated nitriles, vinyl acetate, vinyl propionate, etc. Vinyl ethers such as L 7' tyl vinyl ether and lauryl vinyl ether,
Examples of polyfunctional monomers include ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, ethylene glycol, dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate,
1.5-propylene glycol dimethacrylate), 1.
Acrylates or methacrylates of mono- or polyalkylene glycols such as 3-butylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate, diallyl phthalate, diallyl maleate,
Examples include di- or triallyl compounds such as diallyl fumarate, diallyl succinate, and triallyl isocyanurate, and divinyl compounds such as divinylbenzene and buta-diene.

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 acrylic polymer latex by a general emulsion polymerization method, for example, pure water, an anionic emulsifier, and a water-soluble polymerization initiator are charged into a polymerization reactor with a jacket, and the air inside the can is excluded. Next, monomers copolymerizable with alkyl acrylate and/or alkyl methacrylate are charged, and after emulsification, the inside of the can is heated by a jacket to start the reaction. The reaction is exothermic, and the internal temperature is controlled using a 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 approximately 50 w by the above method.
Although it is possible to produce it up to a concentration of 10 to 30 wt%, it is advantageous in terms of production and handling.

Coagulants for the acrylic polymer latex used in the present invention include metal salts and ammonium salts of groups 1, 2, 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,
Metal salts such as calcium nitrate, calcium acetate, calcium sulfate, calcium phosphate, magnesium chloride, magnesium nitrate, magnesium acetate, magnesium sulfate, magnesium phosphate, aluminum chloride, aluminum nitrate, aluminum acetate, aluminum sulfate, aluminum phosphate, ammonium chloride, Examples include ammonium salts such as ammonium nitrate, ammonium acetate, 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. .

When carrying out an aqueous suspension polymerization method, the amount of water used is 1 to 5 times, preferably 1 to 6 times, the total amount of the acrylic copolymer 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. The acrylic polymer latex is charged and allowed to solidify, then the air in the can is removed, a dispersant such as hydroxyclovir methylcellulose is added, and then vinyl chloride is charged, along with other vinyl compounds if necessary. Thereafter, the material is heated using a jacket to initiate graft copolymerization. Graft copolymerization is an exothermic reaction, and the internal temperature of the jacket is controlled as necessary. After the reaction is complete, unreacted vinyl chloride is removed from the can,
A slurry-like graft copolymer resin is obtained. 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 peroxybipartate, diisopropyl peroxide. Organic peroxides such as oxydicarbonate and dioctyl peroxydicarbonate, 2.2
'-Azopisisoputilonitrino 2.2-Azobis-2,4-dimethylvaleronitrile and other oil-soluble polymerization initiators of azo compounds, and water-soluble polymerization initiators such as potassium persulfate and ammonium persulfate. .

The amount of these polymerization initiators used is per 100 parts by weight of vinyl chloride! The amount is preferably 70.005 to 10 parts by weight.

Dispersants include methylcellulose, ethylcellulose, hydroxyclopylmethylcellulose, hydroxyethylcellulose, polyvinyl alcohol and partially saponified products thereof, gelatin, polyvinylpyrrolidone, starch,
Examples include maleic anhydride-styrene copolymers, which may be used alone or in combination. The amount added is 1 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 90.001 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, and
By incorporating processing aids, antioxidants, fillers, ultraviolet absorbers, pigments, etc., ordinary molding processes can be performed, and its excellent impact resistance and weather resistance can be used for building materials, etc. It is suitably used for.

〔Example〕

Hereinafter, the present invention will be specifically explained with reference to Examples.

Reference Example 1 (Production example of acrylic latex) In a polymerization machine with an internal volume of 5 d equipped with a stirring blade, 200 Ky of deionized water and 7.0 Ky of anionic emulsifier were added. o Kg, ammonium persulfate 0
．． 7 Kg+, n-phthyl acrylate 700 Kf,
1.3-Butylene glycol dimethacrylate 35K
After p was added and the air inside was replaced with nitrogen, polymerization was carried out at 60°C. Fifteen hours after the start of polymerization, the internal temperature began to rise rapidly, so heat was removed through the jacket and 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 Deionized water was poured into a polymerization machine with an internal volume of 7 and equipped with stirring blades.
700 Kf, NaC11.5Kf, partially saponified polyvinyl alcohol 1. OK, methyl cellulose 1
．． 0 to 9.2,2'-Azobisisobutyronitrile OA
After adding 5 kg and removing the air inside with a vacuum pump,
Gu (solid content: 210%) was charged into acrylic polymer latex 840 having a composition shown in Table 1 and having a concentration of 25%, and the acrylic polymer latex was coagulated. Thereafter, vinyl chloride 1,29oK7 was charged and polymerization was carried out at 60°C. Eleven hours after the start of polymerization, the internal pressure of the polymerization machine reached 6.
Since the value decreased to 5 Ky/c++ft, the polymerization reaction was completely stopped. After removing unreacted vinyl chloride salt, the slurry was dehydrated and dried using a conventional method, and white powder particles 12 were obtained.
50~ was obtained. The average particle size of this white powder is 113
The particle size distribution was narrow and stable in μm.

Example-2 Deionized water was poured into a polymerization machine with an internal volume of 7 and equipped with a stirring blade.
700 Kg, At2 (804) 30.9 Kg, partially saponified polyvinyl alcohol 075 Kg, methyl cellulose ays Kg, 2. i-azobisisobutyronitrile 0.075Ky, 2,2'-azobis-2
, 024 Kg of 4-dimethylvaleronitrile was added, and after removing the air inside with a vacuum pump, 600 Ky of acrylic polymer latex with a concentration of 15 Ky and the composition shown in Table 1 was added.
(solid content 90 to 9) was charged under stirring and allowed to solidify.

Thereafter, 1a1'aKg of vinyl chloride was charged, and polymerization was carried out at 57°C. Ten hours after the start of polymerization, the internal pressure of the polymerization machine decreased to 6.5 kg/crlt, so the polymerization reaction was stopped. After removing unreacted vinyl chloride, the slurry was dehydrated and dried using a conventional method, resulting in white powder particles 12.
DOKp 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 In Example-1, polyvinyl alcohol partially saponified product 225Kf1 methyl cellulose 225Kf increased, N
In the same manner as in Example-1 except that act was not charged,
Polymerization was carried out to obtain 1100 kg of white powder particles.

The average particle size of this white powder was as large as 255 μm, and its particle size distribution was also wide.

Comparative Example-2 In Comparative Example-1, partially saponified polyvinyl alcohol 2.525 Kf,) # O-, l: '1
．． Polymerization was carried out in the same manner as in Comparative Example 1, except that the weight was changed to 525 Kg, and white powder particles of 1220 Kp were obtained.

The average particle size of this white powder was 76 μm, and the particle size distribution was wide.

Comparative Example-5 In Example-2, polyvinyl alcohol partially chlorinated product was 1.95 Kp and methyl cellulose was 1.95 Kp.
Polymerization was carried out in the same manner as in Example 2, except that a2(S04)3 was not charged, and white powder particles of 1190 mm 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, the partially saponified polyvinyl alcohol was 2.025Ky, the methyl cellulose was 2.0sK
Polymerization was carried out in the same manner as in Comparative Example 5, except that r was changed, and white powder particles of 1200 Kf 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). In addition, the particle size distribution is 60.80 from the top of the J Engineering S standard sieve.
．． 100.150.200.270 Stack the mesh and the saucer in that order, put 50 tons of sample on the top sieve, give it vibration with a sieve shaker for 15 minutes, and then place the sample on each sieve and saucer. The proportion of resin was determined and expressed in weight percent. In addition, the average particle size is determined by the cumulative total of the residual ratio of each mesh on the horizontal axis of the normal probability table, and the opening of each mesh (μ) on the vertical axis.
m) is plotted, and the cumulative total is expressed as the aperture (μm) of 50%.

〔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 thick, and the average particle size is also large enough. Yes, it is good.

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, in the reaction tank in which the acrylic polymer latex is graft copolymerized, groups I, II, and III of the periodic table are After coagulating with one or more salts selected from the group consisting of metal salts and ammonium salts,
A method for producing a vinyl chloride resin, which comprises graft copolymerizing vinyl chloride by a suspension polymerization method.