JPH04296301A - Dispersion stabilizer for suspension polymerization - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dispersion stabilizer for suspension polymerization comprising a polymer having a polyvinyl alcohol polymer in its side chain. The dispersion stabilizer is used as a dispersion stabilizer during suspension polymerization of vinyl monomers.

0002

BACKGROUND OF THE INVENTION Suspension polymerization is widely used as an industrial method for producing polymers. The quality of the polymer obtained by this polymerization method is influenced by the polymerization rate, water-monomer ratio, polymerization temperature, type and amount of initiator, type of polymerization phase, stirring speed, type and amount of dispersion stabilizer, etc. In particular, it is known that the type of dispersion stabilizer has a very large influence on the moldability and thermal stability of the resulting polymer. Among these, the requirements for dispersion stabilizers for suspension polymerization of vinyl chloride monomers are particularly strict: ■ They must exhibit high dispersion power when used in small amounts, and have the ability to make the particle size distribution of the resulting polymer particles as sharp as possible. (1) It has the ability to make polymer particles uniform and porous, and (2) it has the ability to create polymer particles with a high filling specific gravity. Conventionally, in order to meet these demands, cellulose derivatives such as methylcellulose and carboxymethylcellulose, or various partially saponified polyvinyl alcohol-based polymers have been used alone or in combination, but these dispersion stabilizers are based on vinyl chloride-based polymer particles. They have problems such as low ability to make porosity, slow plasticizer absorption rate, and difficulty in removing residual vinyl chloride monomer.

0003

Problems to be Solved by the Invention The present invention has sufficient dispersion stabilizing ability and can be used as a dispersion stabilizer for suspension polymerization of various vinyl monomers, and is particularly suitable for suspension polymerization of vinyl chloride monomers. The object of the present invention is to provide a dispersion stabilizer for turbid polymerization.

0004

[Means for Solving the Problems] As a result of intensive studies aimed at solving the above problems, the present inventors have found that a dispersion stabilizer for suspension polymerization consisting of a polymer having a polyvinyl alcohol polymer in its side chain is The present invention was completed based on the discovery that the present invention has excellent dispersion stability, and that when applied particularly to vinyl chloride monomers, polymer particles with a sharp particle size distribution, porosity, and high packing density can be obtained.

The polymer which is the dispersion stabilizer for suspension polymerization of the present invention has a vinyl alcohol content of 50 mol% or more and a number average degree of polymerization of 3 to 500. This is the polymer [A] having the following properties. Here, the structure of the main chain of the polymer [A] and the structure of the part connecting the side chain and the main chain are not particularly limited, and include vinyl type polymers and condensation type polymers. Specific examples of these polymers include homopolymers or copolymers of macromonomers having a polyvinyl alcohol polymer in the side chain, monopolymers of polyvinyl ester polymer macromonomers, or homopolymers of polyvinyl ether polymer macromonomers. Polymers obtained by solvolysis or hydrolysis of polymers or copolymers are useful, and polymers with vinyl-type structures such as methacrylic esters, acrylic esters, methacrylamide, acrylamide, and styrene are preferred. used.

The polyvinyl alcohol polymer [I] constituting the side chain of the polymer [A] has a water solubility of the polymer [A],
Affects water dispersibility and dispersion stabilization ability. From the viewpoint of water solubility, water dispersibility, and dispersion stabilization ability, the vinyl alcohol content must be 50 mol% or more, and 70% by mole or more.
It is preferably mol% or more. The number average degree of polymerization of the polyvinyl alcohol polymer [I] affects the dispersion stabilizing ability and the properties of the obtained polymer particles, and needs to be 3 to 500, preferably 10 to 300, and more preferably 10 to 300. Preferably it is 10-200. Polyvinyl alcohol polymer [
If the degree of polymerization of [I] is too low, the dispersion stabilizing ability will decrease, and if it is too high, the properties as a polyvinyl alcohol polymer will be too strongly expressed, which is not preferable. The content of units containing polymer [I] in polymer [A] affects water solubility, water dispersibility, and dispersion stabilization ability, and is 10 to 100% by weight,
Preferably it is 15 to 100% by weight, and if the content of units containing polymer [I] is too low, the desired performance may not be obtained. Units other than vinyl alcohol units constituting the polymer [I] can be contained in an amount of less than 50 mol% depending on the purpose.

Examples of such units include the following units. i.e. ethylene, propylene, 1-
Olefins such as butene and isobutene, vinyl esters such as vinyl acetate, vinyl formate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl versatate, vinyl laurate, vinyl stearate, vinyl benzoate, acrylic acid, its salts, methyl acrylate;
Ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-acrylate
-Acrylic acid esters such as butyl, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, octadecyl acrylate, methacrylic acid and its salts, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, methacrylate Methacrylic acid esters such as i-propyl acid, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, acrylamide, N-methylacrylamide, N-ethylacrylamide, N,N
- acrylamide derivatives such as dimethylacrylamide, diacetone acrylamide, acrylamide propane sulfonic acid and its salts, acrylamide propyl dimethylamine and its salts or its quaternary salts, N-methylolacrylamide and its derivatives, methacrylamide, N-methylmethacrylamide, Methacrylamide derivatives such as N-ethylmethacrylamide, methacrylamidepropanesulfonic acid and its salts, methacrylamidepropyldimethylamine and its salts or its quaternary salts, N-methylolacrylamide and its derivatives, methyl vinyl ether, ethyl vinyl ether, n- Propyl vinyl ether, i-propyl vinyl ether, n-
Butyl vinyl ether, i-butyl vinyl ether, t
- Vinyl ethers such as butyl vinyl ether, dodecyl vinyl ether, stearyl vinyl ether, nitriles such as acrylonitrile, methacrylonitrile, vinyl halides such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, allyl acetate, allyl chloride, etc. maleic acid and its salts or its esters, itaconic acid and its salts or its esters, vinyl silyl compounds such as vinyltrimethoxysilane, etc.

Preferred examples of the polymer [A] of the present invention include homopolymers or copolymers of polyvinyl alcohol polymer macromonomers. When the polymer [A] is a copolymer, structural units other than those containing the polymer [I] may be used depending on the purpose of adjusting the hydrophilicity or hydrophobicity of the polymer [A], imparting ionicity, etc. selected. There are no particular restrictions on the type and amount of the structural unit as long as it falls within the above range, and examples include the following units. That is, olefins such as ethylene, propylene, 1-butene, isobutene, methyl acrylate, methacrylic acid and its salts, methyl methacrylate, ethyl methacrylate,
n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate,
t-Butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, 2-hydroxyethyl methacrylate, 2-dimethylaminoethyl methacrylate and its salts or quaternary salts thereof, 2-diethylaminoethyl methacrylate and its salt or its quaternary salt, methacrylic acid (2-hydroxy)
Methacrylic acid esters such as dimethylaminopropyl and 3-trimethoxysilylpropyl methacrylate, styrene, p-methylstyrene, α-methylstyrene, chloromethylstyrene, p-styrenesulfonic acid and its salts, p-hydroxystyrene and its Styrene derivatives, acrylamide, N-methylacrylamide, N
- Acrylamide derivatives such as ethyl acrylamide, N,N-dimethylacrylamide, diacetone acrylamide, acrylamide propanesulfonic acid and its salts, acrylamide propyldimethylamine and its salts or its quaternary salts, N-methylolacrylamide and its derivatives, methacrylamide , N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamide propanesulfonic acid and its salts, methacrylamide propyldimethylamine and its salts or quaternary thereof, N-methylolmethacrylamide and its derivatives, etc., methacrylamide derivatives, N -vinylpyrrolidone, methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n
-butyl vinyl ether, i-butyl vinyl ether,
t-butyl vinyl ether, dodecyl vinyl ether,
Vinyl ethers such as stearyl vinyl ether, nitriles such as acrylonitrile and methacrylonitrile, vinyl halides such as vinyl chloride, vinylidene chloride, vinyl fluoride, and vinylidene fluoride, allyl compounds such as allyl acetate, allyl chloride, and allyl alcohol; Maleic anhydride, maleic acid and its salts or its esters, fumaric acid and its salts or its esters, itaconic acid and its salts or its esters, etc., isopropenyl acetate,
Examples include N-vinylimidazole. Further, structural units other than these include macromonomers such as polyoxyalkylene, polyoxyalkylene phosphate, polystyrene, polymethyl methacrylate, and polysiloxane.

The polymer [A] constituting the dispersion stabilizer for suspension polymerization of the present invention can be synthesized by several methods, including synthesis by homopolymerization or copolymerization of a polyvinyl alcohol polymer macromonomer, or synthesis by polyacetic acid polymerization. A method of hydrolyzing a homopolymer or copolymer of a polyvinyl ester polymer macromonomer such as a vinyl polymer macromonomer is preferred in terms of controlling the composition and structure of the polymer [A]. There is no particular restriction on the structure of the polyvinyl alcohol polymer macromonomer or polyvinyl acetate polymer macromonomer, and methacrylic acid amide, acryl amide, acrylamide, etc., whose unsaturated double bond structure has excellent radical polymerizability, Those having a methacrylic ester and styrene structure are preferably used, and macromonomers having a methacrylic amide, acryl amide and methacrylic ester structure are particularly preferably used. The polymerization and subsequent solvolysis or hydrolysis of the macromonomer is carried out in conventional manner.

Suspension polymerization using the dispersion stabilizer for suspension polymerization of the present invention is usually carried out by dissolving or dispersing the dispersion stabilizer in an aqueous medium, dispersing monomers with an initiator dissolved therein, or dispersing the monomers in which the initiator has been dissolved. This is done by charging the polymer, dispersing it, and adding an initiator. Since the amount of dispersion stabilizer greatly affects the quality of the obtained polymer, it is usually 0.005 to 1
% by weight, preferably in the range of 0.01 to 0.5% by weight. In addition, cellulose derivatives, partially saponified polyvinyl alcohol polymers, and low-molecular-weight surfactants that have been conventionally used as dispersion stabilizers may be used in combination with the dispersion stabilizer of the present invention within the range that does not impair the effects of the present invention. There is nothing I can do. The initiator used for suspension polymerization is usually an oil-soluble initiator, such as peroxides such as benzoyl peroxide and lauroyl peroxide, and peroxycarbonates such as di-n-propyl peroxydicarbonate and diisopropyl peroxydicarbonate. 2,2'-Azobisisobutyronitrile, 2
, 2'-azobis-2,4-dimethylvaleronitrile and the like are used. The polymerization temperature is appropriately set depending on the type of monomer to be polymerized and the initiator used, but is usually in the range of 5 to 100°C. Suspension polymerization using the dispersion stabilizer of the present invention can be used for the homopolymerization or copolymerization of any radically polymerizable monomer, but especially vinyl chloride, vinylidene chloride, styrene and its derivatives, methacrylic acid It is particularly effective in the suspension polymerization of methacrylic esters and acrylic esters such as methyl and methyl acrylate, and vinyl esters such as vinyl acetate.

[0011]

[Examples] The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to these in any way. In addition, "parts" and "%" in the examples refer to "parts by weight" and "% by weight," respectively, unless otherwise specified.
” represents.

Reference Example 1 Synthesis of polyvinyl acetate macromonomer Polyvinyl acetate 60 having a number average degree of polymerization of 31 and having a 2-hydroxythio group at one end was placed in a reactor equipped with a stirrer, a reflux condenser and a dropping funnel. 1 part, 40 parts of toluene and 4.16 parts of pyridine were added, and the mixture was thoroughly stirred at room temperature. While stirring the reactor at room temperature, 5.50 parts of methacrylic acid chloride distilled just before and 10 parts of dehydrated toluene were thoroughly mixed and then uniformly added dropwise over 1 hour using a dropping funnel. After the dropwise addition was completed, stirring was continued for an additional 3 hours at room temperature. Next, 1.70 parts of methanol was added and stirred for 1 hour, and then toluene, methanol, etc. were distilled off under reduced pressure at 40°C while adding 400 parts of toluene in 4 portions to form a white precipitate. By filtering off the material, a 53.2% toluene solution of the polymer was obtained. A portion of this toluene solution was poured into n-hexane to recover the polymer, purified by reprecipitation twice with acetone-hexane, and then dried under reduced pressure at 40°C. When this purified polymer was measured by proton NMR using CDCl3 as a solvent, it was found to be a polyvinyl acetate macromonomer with a number average degree of polymerization of 31 and having a methacrylate ester structure at one end. Subsequently, toluene was distilled off under reduced pressure, and methanol was added and distilled off repeatedly to remove toluene, thereby obtaining a 60.3% methanol solution of polyvinyl acetate macromonomer.

Reference Example 2 100 parts of the methanol solution (concentration 60.3%) of the polyvinyl acetate macromonomer obtained in Reference Example 1 was placed in a reactor equipped with a stirrer, a reflux condenser, a nitrogen introduction tube, and a thermometer. The mixture was prepared and replaced with nitrogen by bubbling nitrogen gas at room temperature. The temperature of the reactor was started to rise, and when the internal temperature reached 60°C, an initiator solution in which 0.24 parts of 2,2-azobisisobutyronitrile was dissolved in 20 parts of methanol and the atmosphere was replaced with nitrogen was added to carry out polymerization. started. After continuing the polymerization under stirring for 20 hours,
The polymerization was stopped by cooling, and then 60.3 parts of methanol was added, and the temperature was adjusted to 40°C. 10% of sodium hydroxide
Add 28 parts of methanol solution, perform methanol decomposition reaction, and after the system gels, pulverize and add 50 parts of methanol.
The mixture was left at room temperature for 24 hours to complete the reaction. Subsequently, 30 parts of methyl acetate and 5 parts of water were added, heated at 50°C for 1 hour, and purified by Soxhlet washing with methanol to form a polyvinyl alcohol polymer [I] with a number average degree of polymerization of 31 in the side chain. A polymer (referred to as polymer [A]-1) having the following properties was obtained. The polymer is a homopolymer of polyvinyl alcohol macromonomer, and H1-NM in d6-DMSO solution
From the R measurement, the vinyl alcohol content of the polyvinyl alcohol polymer portion was 99.0 mol%.

Reference Examples 3 to 8 Number average polymerization degree 60 to 1 synthesized by the same method as Reference Example 1
A homopolymer or copolymer of a polyvinyl acetate-based macromonomer obtained by polymerizing the polyvinyl acetate-based macromonomer No. 12 in the same manner as in Reference Example 2 was prepared according to the method shown in Reference Example 2. , polymers having various polyvinyl alcohol-based polymers in their side chains by solvolysis ([
A]-2 to [A]-7) were obtained. The results are shown in Table 1.

[Table 1]

Examples 1 to 4 A predetermined amount of the polymer obtained in the above reference example was weighed into a reactor equipped with a stirrer, a reflux condenser, a nitrogen introduction tube, and a thermometer.
100 parts of distilled water was added, and the mixture was heated and stirred at 90°C to dissolve. The mixture was cooled to room temperature under nitrogen gas flow, and 50 parts of a monomer containing a predetermined amount of a polymerization initiator was added and heated to initiate suspension polymerization. After the polymerization was completed, the resulting polymer was cooled to room temperature, filtered, washed thoroughly with water, and then dehydrated and dried. The polymerization recipe and results are summarized in Table 2.

Comparative Examples 1 and 2 Except for using PVA-217 (manufactured by Kuraray Co., Ltd., polymerization degree 1700, saponification degree 88 mol%) as a polymerization stabilizer,
Emulsion polymerization was carried out in the same manner as in Example 1 or 3. The polymerization recipe and results are summarized in Table 2.

[Table 2]

Examples 5 to 8 In a glass-lined pressure-resistant reaction vessel equipped with a stirrer, a nitrogen inlet tube, and a thermometer, 40 parts of deionized water, a predetermined amount of a 2% aqueous solution of a polymer, and a solution of diisopropyl peroxydicarbonate were added. 0.009 part of 50% toluene solution was charged. After degassing the inside of the autoclave to 50 mmHg, 30 parts of vinyl chloride monomer was charged, and 5 parts of vinyl chloride monomer was added while stirring.
Polymerization was carried out by raising the temperature to 7°C. After polymerization for 7 hours, the polymerization was stopped by cooling, and after purging unreacted monomers, the contents were taken out and dehydrated and dried to obtain a polymer. Table 3 shows the polymerization conditions and properties of the polyvinyl chloride obtained. The physical properties of polyvinyl chloride were evaluated by the following method. (1) Particle size distribution: Measured by dry sieve analysis using a wire gauze based on Tyler mesh. (2) Filling specific gravity: Measured according to JIS K6721-1959. (3) Plasticizer absorber: Using a planetary mixer connected to a plastograph, put 100 parts of vinyl chloride resin and 50 parts of dioctyl phthalate into a container kept at 80°C, and knead at each hour while stirring. Record the torque and indicate the kneading time at the point where the kneading torque decreased. (4) Residual vinyl chloride monomer: A certain amount of vinyl chloride resin was dissolved in tetrahydrofuran, and the vinyl chloride monomer content in the vinyl chloride resin was determined by gas chromatography.

Comparative Example 3 Except for using PVA-420 (manufactured by Kuraray Co., Ltd., polymerization degree 2000, saponification degree 80 mol%) as a dispersion stabilizer,
Polymerization was carried out in the same manner as in Example 5. The polymerization conditions and results are summarized in Table 3.

[Table 3]

[0019]

Effects of the Invention The dispersion stabilizer for suspension polymerization of the present invention can be used as a dispersion stabilizer for suspension polymerization of various monomers due to the diversity of its structure and composition. This is clearer than the example.

Claims (2)

[Claims] 1. A dispersion stabilizer for suspension polymerization comprising a polymer having a polyvinyl alcohol polymer having a vinyl alcohol content of 50 mol % or more and a number average degree of polymerization of 3 to 500 in its side chain. [Claim 2] A polymer having a polyvinyl alcohol polymer in a side chain having a vinyl alcohol content of 50 mol% or more and a number average degree of polymerization of 3 to 500 has a macromonomer unit composed of a polyvinyl alcohol polymer. The dispersion stabilizer for suspension polymerization according to claim 1, which is a polymer.