JP2002097209A - Dispersion stabilizer for suspension polymerization of vinyl compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dispersion stabilizer for the suspension polymerization of a vinyl compound whereby the suspension polymerization stability is significantly excellent even in using a small amount and a vinyl polymer particle with high absorbing performance of plasticizer, a sharp particle size distribution, porous and a large bulk specific gravity can be produced by the polymerization of the vinyl compound. SOLUTION: The stabilizer comprises (A) a vinyl alcohol polymer having the ethylene unit content of 0.5 to 20 mol%, the saponification degree of 60 mol% or more and the polymerization degree of 600 or more and (B) the polymer having the saponification degree of 20 to 60 mol% and the polymerization degree of 100 to 600.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a dispersion stabilizer for suspension polymerization of vinyl compounds. More specifically, the present invention has an effect such that a small amount of the polymer scale adheres to the inner wall of the polymerization tank when used in a small amount, and the suspension polymerization stability is remarkably excellent. The present invention relates to a dispersion stabilizer for suspension polymerization of a vinyl compound, which has high absorption performance of an agent, has a sharp particle size distribution, is porous, and can produce vinyl polymer particles having a large bulk specific gravity.

[0002]

2. Description of the Related Art In the production of vinyl polymers such as vinyl chloride resins, industrially, a vinyl compound such as vinyl chloride is dispersed in an aqueous medium in the presence of a dispersion stabilizer to prepare an oil-soluble initiator. Is widely used by suspension polymerization in which polymerization is performed using In general, factors that control the quality of a vinyl polymer include a polymerization rate, a water-monomer ratio, a polymerization temperature, a type and amount of an initiator, a type of a polymerization tank, a stirring speed, and a type of a dispersion stabilizer. However, among these, the effect of the type of the dispersion stabilizer is very large.

The performance required of a dispersion stabilizer for suspension polymerization of vinyl compounds is as follows: (1) The suspension polymerization stability is remarkably excellent when a small amount is used, and the particle size distribution of the resulting vinyl polymer particles Work to sharpen as much as possible,
(2) To increase the rate of plasticizer absorption to facilitate processability, to facilitate removal of monomers such as vinyl chloride remaining in the polymer particles, and to prevent the formation of fish eyes and the like in molded articles. Has the function of making the polymer particles as uniform and as porous as possible, and (3) the function of forming polymer particles having a large bulk specific gravity.
(4) There is no scale attached to the polymerization tank and the like. Conventionally, as a dispersion stabilizer for suspension polymerization of a vinyl compound, cellulose derivatives such as methylcellulose and carboxymethylcellulose, as well as partially saponified polyvinyl alcohol and the like have been used alone or in appropriate combination. However, conventional dispersion stabilizers do not always fully satisfy the required performance described above.

Further, JP-A-54-127490, JP-A-1-95104, and JP-A-3-1403
03, JP-A-6-80709, JP-A-8-80709
In JP-A-259609 and the like, a dispersion stabilizer for suspension polymerization of a vinyl compound comprising a modified polyvinyl alcohol containing an ethylene unit has been proposed. JP 54
With respect to the dispersion stabilizer composed of ethylene-modified polyvinyl alcohol proposed in JP-A-127490, when a modified polyvinyl alcohol having a large ethylene unit content is used, the workability is poor due to poor water solubility of the dispersion stabilizer. In order to deteriorate or improve the solubility of the dispersion stabilizer, a water-organic solvent-based medium must be used, and when an organic solvent is used, the wastewater after suspension polymerization becomes a factor that has an adverse effect on the environment. , There was a problem. JP-A-1-951
In a dispersion stabilizer comprising an ethylene-modified polyvinyl alcohol having an ionic group in a side chain proposed in JP-A No. 04 and JP-A-3-140303, although water solubility is improved, suspension polymerization of vinyl chloride is carried out. There has been a problem that foam is sometimes easily formed and scale is easily attached to the polymerization tank. The dispersion stabilizer comprising ethylene-modified polyvinyl alcohol proposed in JP-A-6-80709 gives a relatively well-balanced vinyl chloride resin, but has a sharp plasticizer absorbency and sharp particle size distribution of the vinyl chloride resin. That is not always a satisfactory level. Further, the dispersion stabilizer proposed in JP-A-8-259609, which uses an ethylene-modified polyvinyl alcohol and a polyvinyl alcohol-based polymer in combination, is excellent in defoaming effect in a polymerization tank, and therefore, suspends vinyl chloride. Although the problem that scale adheres to the polymerization tank due to foaming during turbid polymerization is improved, the plasticizer absorbency and sharpness of the particle diameter distribution of the obtained vinyl chloride resin have not necessarily reached a sufficiently satisfactory level. Absent.

[0005]

SUMMARY OF THE INVENTION Under such circumstances, the present invention provides remarkably excellent suspension polymerization stability even when used in a small amount, and furthermore, the suspension polymerization of a vinyl compound causes absorption of a plasticizer. An object of the present invention is to provide a dispersion stabilizer for suspension polymerization of a vinyl compound, which has high performance, has a sharp particle size distribution and is porous, and can produce a vinyl polymer particle having a large bulk specific gravity. . Further, another object of the present invention is that the vinyl-based compound remaining in the vinyl-based polymer particles can be easily removed, the scattering of powder during handling is small, and the property of being able to penetrate into a molding machine is good. It is an object of the present invention to provide a dispersion stabilizer for suspension polymerization of a vinyl compound which can produce a vinyl polymer particle having the following.

[0006]

The present inventors have conducted intensive studies and found that the ethylene unit content was 0.5 to 20 mol%, the saponification degree was 60 mol% or more, and the polymerization degree was 600 or more. A dispersion stabilizer for suspension polymerization of a vinyl compound comprising a vinyl alcohol polymer (A) and a vinyl alcohol polymer (B) having a degree of saponification of 20 to 60 mol% and a degree of polymerization of 100 to 600 is the above problem. Have been found to be effective in achieving the above, and the present invention has been completed.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The content of the ethylene unit of the vinyl alcohol polymer (A) used in the present invention is 0.5 to 20 mol%, preferably 0.5 to 10 mol%, more preferably 1 to 10 mol%. And more preferably 1.5
８8 mol%. When the content of the ethylene unit is less than 0.5 mol%, the scale adheres to the polymerization tank during suspension polymerization of the vinyl compound, and when the content exceeds 20 mol%, the vinyl alcohol compound is used. The water solubility of the polymer decreases, and the handleability deteriorates. The degree of saponification of the vinyl alcohol polymer (A) is at least 60 mol%, preferably from 65 to 95 mol%, more preferably from 70 to 9 mol%.
0 mol%. If the degree of saponification is less than 60 mol%, the water solubility of the vinyl alcohol-based polymer decreases, and the handleability deteriorates. The degree of polymerization of the vinyl alcohol polymer (A) is 600 or more, preferably 600
8000, more preferably 650-3500. When the polymerization degree of the vinyl alcohol-based polymer is less than 600, the polymerization stability is lowered when the vinyl-based compound is subjected to suspension polymerization.

The degree of saponification of the vinyl alcohol polymer (B) used in the present invention is from 20 to 60 mol%, preferably from 25 to 60 mol%, and more preferably from 30 to 55 mol%. When the degree of saponification is out of the range of 20 to 60 mol%, the particle size distribution of the vinyl polymer particles obtained by suspension polymerization of the vinyl compound becomes wide. The polymerization degree of the vinyl alcohol polymer (B) is 10
0 to 600, preferably 150 to 550,
More preferably, it is 200 to 550. Polymerization degree is 10
If it is less than 0, the polymerization stability is deteriorated when the vinyl compound is subjected to suspension polymerization, and if it is more than 600, the plasticizer absorption of the vinyl polymer obtained by the suspension polymerization of the vinyl compound. Worsens.

The difference between the degree of saponification of the vinyl alcohol polymer (A) and the vinyl alcohol polymer (B) is not less than 15 mol% and / or the difference between the degrees of polymerization is not less than 20%.
It is preferably 0 or more.

In the dispersion stabilizer for suspension polymerization of the present invention,
There is no particular limitation in the strict meaning of the ratio of the vinyl alcohol-based polymer (A) and the vinyl alcohol-based polymer (B), but usually, the weight ratio of the component (A) / the component (B) is 95/5 to 5/5. 20/80, preferably 95/5
３０30/70, more preferably 95/5 to 50
/ 50. The weight ratio of component (A) / component (B) is 95
When the ratio exceeds / 5, the plasticizer absorption performance of the vinyl polymer obtained by suspension polymerization of the vinyl compound tends to deteriorate, and the particle size distribution tends to be wide. In addition, when the vinyl compound is subjected to suspension polymerization, the polymerization stability may be reduced.

In the present invention, the amount of the dispersion stabilizer for suspension polymerization is not particularly limited.
The amount is preferably 0.01 to 5 parts by weight relative to 0 parts by weight, and 0.1 to 5 parts by weight.
02 to 2 parts by weight is more preferable, and 0.02 to 1 part by weight is further preferable. When the amount is less than 0.01 part by weight, the polymerization stability tends to decrease when the vinyl compound is subjected to suspension polymerization. When the amount exceeds 5 parts by weight, the waste liquid after the suspension polymerization becomes cloudy, There is a tendency for the chemical oxygen demand (COD) to be high.

The vinyl alcohol polymer (B) used in the present invention is water-insoluble or water-dispersible, into which ionic groups such as sulfonic acid groups, amino groups, ammonium groups, carboxyl groups and cationic groups are introduced. By doing so, self-emulsifying properties can be imparted. When the ionic group is not introduced, the water solubility or water dispersibility of the vinyl alcohol polymer (B) is reduced, and the handleability may be deteriorated.

The vinyl alcohol polymer (A) used in the present invention can be improved in water solubility by introducing an ionic group such as an ammonium group, a carboxyl group, a sulfonic acid group and an amino group. Alternatively, a nonionic group or a (long chain) alkyl group may be introduced. The vinyl alcohol polymer (A) is 5 to 100
It is preferably water-soluble in water at a temperature of 10 ° C, preferably 10-90 ° C.

Here, the degree of saponification of a vinyl alcohol polymer into which an ionic group, a nonionic group or a (long chain) alkyl group has been introduced is determined from the ratio of the vinyl ester group to the vinyl alcohol group. It does not include the degree of saponification such as a functional group, a nonionic group or a (long chain) alkyl group.

In the present invention, the method for producing the vinyl alcohol-based polymer (A) is not particularly limited, and a vinyl ester-based polymer (A) may be prepared according to a conventionally known method, for example, a method described in JP-A-8-259609. Mers,
Ethylene and, if necessary, a monomer having an ionic group are copolymerized, and the obtained copolymer is saponified by a conventional method, or a vinyl ester in the presence of a thiol compound such as thiolacetic acid or mercaptopropionic acid. It can also be obtained by a terminal modification method in which a system monomer and ethylene are copolymerized and saponified.

The method for producing the vinyl alcohol polymer (B) is also not particularly limited, and a vinyl ester monomer and, if necessary, a monomer having an ionic group may be used according to a conventionally known method. Copolymerization, saponification of the resulting copolymer by a conventional method, or polymerization of a vinyl ester monomer in the presence of a thiol compound such as thiolacetic acid or mercaptopropionic acid, and a terminal modification method of saponifying it. Can also be obtained by

As a method for copolymerizing ethylene with a vinyl ester monomer, conventionally known methods such as a solution polymerization method, a bulk polymerization method, a suspension polymerization method, and an emulsion polymerization method can be applied.
As the polymerization initiator, an azo-based initiator, a peroxide-based initiator, a redox-based initiator, and the like are appropriately selected depending on the polymerization method. As the saponification reaction, alcoholysis and hydrolysis using a conventionally known alkali catalyst or acid catalyst can be applied. Among them, a saponification reaction using methanol as a solvent and using a NaOH catalyst is simple and most preferable.

The vinyl ester monomers include, for example, vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate,
Examples thereof include vinyl versatate, vinyl caproate, vinyl caprylate, vinyl laurate, vinyl palmitate, vinyl stearate, vinyl oleate, and vinyl benzoate, with vinyl acetate being most preferred.

In the present invention, the monomer having an ionic group used for introducing an ionic group into the vinyl alcohol-based polymer, if necessary, is not particularly limited. For example, ethylene sulfonic acid, Sulfonic acid-containing monomers such as (meth) allylsulfonic acid, sulfoalkylmalate, sulfoalkyl (meth) acrylate, acrylamido-2-methylpropanesulfonic acid and salts thereof; N- (1,1-dimethyl-3-) Dimethylaminopropyl) (meth) acrylamide, N- (1,1-dimethyl-3-dimethylaminobutyl) (meth) acrylamide, N-vinylimidazole, 2-methyl-N-vinylimidazole, vinyl-3-dimethylaminopropyl Ether, vinyl-2-dimethylaminoethyl ether,
Amino or ammonium group-containing monomers such as allyl-3-dimethylaminopropyl ether, allyldimethylamine and methallyldimethylamine; carboxyl groups such as crotonic acid, maleic acid, fumaric acid, itaconic acid and (meth) acrylic acid Contained monomers and the like.

In the present invention, the vinyl alcohol-based polymer (A) and the vinyl alcohol-based polymer (B) may contain other monomer units as long as the gist of the present invention is not impaired. Examples of the comonomer that can be used include α- such as propylene, n-butene, and isobutylene.
Olefins; acrylic acid and its salts; methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, 2-acrylic acid
Acrylic esters such as ethylhexyl, dodecyl acrylate and octadecyl acrylate; methacrylic acid and its salts; methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, methacrylic acid Methacrylic esters such as i-butyl, t-butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, octadecyl methacrylate; acrylamide; N-methylacrylamide, N-ethylacrylamide, N, N-dimethylacrylamide, Acetone acrylamide, acrylamidopropanesulfonic acid and its salts, acrylamidopropyldimethylamine and its salts or quaternary salts, N-methylolacrylamide and its derivatives Which acrylamide derivative; methacrylamide; N-methyl methacrylamide, N-ethyl methacrylamide, methacrylamidopropanesulfonic acid and its salt, methacrylamidopropyldimethylamine and its salt or quaternary salt thereof, N-methylol methacrylamide and its derivative Methacrylamide derivatives; vinyl ethers such as 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, stearyl vinyl ether; acrylonitrile, methacrylic acid Nitriles such as lonitrile; vinyl halides such as vinyl chloride and vinyl fluoride; vinylidene chloride, Halogenated vinylidenes such as vinylidene halide; allyl compounds such as allyl acetate and allyl chloride; unsaturated dicarboxylic acids such as maleic acid, itaconic acid and fumaric acid and salts or esters thereof; vinylsilyl compounds such as vinyltrimethoxysilane; And isopropenyl.

In the present invention, the vinyl alcohol-based polymer (A) and the vinyl alcohol-based polymer (B) are usually dissolved or dispersed separately or in a mixture in an aqueous medium, and the suspension of the vinyl compound is added. Used for turbid polymerization.

As the dispersion stabilizer for suspension polymerization of the present invention, a heat-treated vinyl alcohol polymer (A) is used, whereby the stability during suspension polymerization is further improved. The condition of the heat treatment is not particularly limited, but is usually 0.5 to 100 ° C. in an oxygen, air or nitrogen atmosphere at a temperature of 100 to 200 ° C.
It is preferable to heat for 20 hours. Temperature during heat treatment is 1
If the temperature is lower than 00 ° C., the effect of improving the stability during suspension polymerization by heat treatment may not be sufficiently exhibited, and if it is higher than 200 ° C., the dispersion stabilizer for suspension polymerization may be colored. At this time, in order to suppress the coloring of the dispersion stabilizer for suspension polymerization due to the heat treatment, the vinyl alcohol-based polymer (A) is added before the heat treatment.
Is preferably washed with a solvent such as methanol.

In the dispersion stabilizer for suspension polymerization of the present invention,
When a heat-treated vinyl alcohol polymer (A) is used, the suspension polymerization stability is remarkably excellent when used in a small amount, and the coloring is suppressed when the polymer obtained by the suspension polymerization is processed. Therefore, the vinyl alcohol-based polymer (A) has a pKa at 25 ° C. of 3.5 to 3.5.
It preferably contains 5.5 acid and / or its metal salt (C). There is no particular limitation on the type of acid that can be used, and specific examples thereof include acetic acid (pKa 4.7).
6), propionic acid (pKa 4.87), butyric acid (pKa
4.63), octanoic acid (pKa 4.89), adipic acid (pKa 5.03), benzoic acid (pKa 4.00),
Formic acid (pKa 3.55), valeric acid (pKa 4.63),
Heptanoic acid (pKa 4.66), lactic acid (pKa 3.6)
6), phenylacetic acid (pKa 4.10), isobutyric acid (p
Ka4.63), cyclohexanecarboxylic acid (pKa)
4.70). Acids which can be particularly preferably used in terms of the effect to be exhibited are acetic acid, propionic acid and lactic acid. The metal salt of the above-mentioned acid is not particularly limited, but usually, a metal salt composed of the above-mentioned acid and an alkali metal such as sodium and potassium is used, and sodium acetate is particularly preferably used.

The above-mentioned acid and / or its metal salt (C)
Is preferably 0.05 to 2 parts by weight, more preferably 0.1 to 1.7 parts by weight, and still more preferably 0.1 to 1.7 parts by weight, based on 100 parts by weight of the vinyl alcohol polymer (A).
2 to 1.5 parts by weight. Acid and / or metal salt thereof (C) for vinyl alcohol polymer (A)
If the content is less than 0.05 parts by weight, the effect of improving the stability during suspension polymerization by heat treatment will be reduced. If it exceeds 2 parts by weight, the dispersion stabilizer for suspension polymerization will be colored during heat treatment, When the polymer obtained by the turbid polymerization is processed, the polymer is undesirably colored.

Next, a method for suspension polymerization of a vinyl compound using the dispersion stabilizer for suspension polymerization of the present invention will be described.

In the suspension polymerization of a vinyl compound in an aqueous medium using the dispersion stabilizer for suspension polymerization of the present invention, the temperature of the aqueous medium is not particularly limited. Warm water of at least ℃ is also preferably used. The aqueous medium can consist of pure water as well as aqueous solutions containing various additional components or aqueous media containing other organic solvents. When the aqueous medium is charged into the polymerization reaction system, the supply amount may be any amount that can sufficiently heat the polymerization reaction system. Further, in order to enhance the heat removal efficiency, a polymerization vessel equipped with a reflux condenser is also preferably used.

The dispersion stabilizer for suspension polymerization of the present invention may be used alone, but polyvinyl alcohol, methylcellulose, hydroxyethylcellulose, hydroxyethylcellulose, and the like usually used when suspension-polymerizing a vinyl compound in an aqueous medium are used. Water-soluble polymers such as water-soluble cellulose ethers such as propylcellulose and hydroxypropylmethylcellulose, and gelatin; oil-soluble emulsifiers such as sorbitan monolaurate, sorbitan trioleate, glycerin tristearate, and ethylene oxide propylene oxide block copolymer; polyoxyethylene sorbitan mono Laurate, polyoxyethylene glycerin oleate,
A water-soluble emulsifier such as sodium laurate may be used in combination. The amount added is not particularly limited, but is preferably 0.01 to 1.0 part by weight per 100 parts by weight of the vinyl compound.

Other various additives can be added as needed. Examples of the additives include polymerization regulators such as acetaldehyde, butyraldehyde, trichloroethylene, perchloroethylene, and mercaptans, and polymerization inhibitors such as phenol compounds, sulfur compounds, and N-oxide compounds. It is also optional to add a pH adjuster, a scale inhibitor, a crosslinking agent, and the like,
A plurality of the above additives may be used in combination. On the other hand, as the polymerization initiator, those conventionally used for the polymerization of vinyl compounds such as vinyl chloride can be used. For example, diisopropyl peroxydicarbonate, di-
Percarbonate compounds such as 2-ethylhexyl peroxydicarbonate and diethoxyethyl peroxydicarbonate; t-butyl peroxyneodecanate;
Perester compounds such as α-cumylperoxyneodecanate and t-butylperoxydecanoate; acetylcyclohexylsulfonyl peroxide, 2,4,4-
Peroxides such as trimethylpentyl-2-peroxyphenoxyacetate; 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis ( 4-methoxy-2,
Azo compounds such as 4-dimethylvaleronitrile) and the like, and further, potassium persulfate, ammonium persulfate, hydrogen peroxide and the like can be used in combination.

The vinyl compounds to which the dispersion stabilizer for suspension polymerization of the present invention can be applied include, for example, vinyl chloride, vinylidene chloride, alkyl vinyl ether, maleic anhydride, acrylonitrile, itaconic acid, styrene and the like. Vinyl esters such as vinyl acetate and vinyl propionate, methyl (meth) acrylate, (meth)
Examples thereof include (meth) acrylates such as ethyl acrylate and α-olefins such as ethylene, propylene, isobutene and isoprene. Representative of these vinyl compounds is vinyl chloride. Vinyl chloride is used alone, or a mixture of vinyl chloride as a main component and other monomers (at least 50% by weight of vinyl chloride) is used. can do. Examples of the comonomer to be copolymerized with vinyl chloride include vinyl esters such as vinyl acetate and vinyl propionate; (meth) acrylates such as methyl (meth) acrylate and ethyl (meth) acrylate; ethylene and propylene. Α-olefins, maleic anhydride, acrylonitrile, itaconic acid, styrene, vinylidene chloride, vinyl ether and the like.

In the suspension polymerization of a vinyl compound using the dispersion stabilizer for suspension polymerization of the present invention, the charge ratio of each component, the polymerization temperature and the like are conventionally determined by the suspension polymerization of a vinyl compound such as vinyl chloride. What is necessary is just to determine according to the employ | adopted conditions. Further, there is no limitation on the order and ratio of the vinyl compound, the polymerization initiator, the dispersion stabilizer, the aqueous medium and other additives. Further, a method in which warm water is used as the aqueous medium and the vinyl compound is heated before the vinyl compound is charged into the polymerization vessel is also preferably used.

[0031]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. In the following examples, “%” and “parts” are “% by weight” unless otherwise specified.
And "parts by weight". In the following, polyvinyl alcohol is referred to as PVA and polyvinyl acetate is referred to as PVA.
c, The vinyl alcohol-based polymer may be abbreviated as a PVA-based polymer.

(Analysis of PVA Polymer) (1) Measurement of Degree of Polymerization The degree of polymerization of the PVA polymer was measured according to JIS K6726. (2) Measurement of Degree of Saponification The degree of saponification of the PVA-based polymer was measured according to JIS K6726. (3) Determination of acid metal salts Capillary tube type isotachophoresis analyzer manufactured by Shimadzu Corporation (I
Using P-3A), sodium acetate contained in the PVA-based polymer was quantified by electrophoretic analysis. (4) Colorability at the time of heat treatment After heat treatment of the PVA-based polymer at 150 ° C. for 2 hours in an air atmosphere, the degree of coloring of the PVA-based polymer is visually observed.
Evaluation was made according to the following criteria. ：: no change △: slightly yellowish ×: reddish brown

(Polymerization of Vinyl Chloride Monomer and Evaluation of Characteristics of Obtained Vinyl Chloride Polymer) (1) Particle Size Distribution The particle size distribution was measured by dry sieve analysis using a metal mesh based on Tyler mesh. did. (2) Bulk specific gravity The bulk specific gravity of the vinyl chloride polymer was measured according to JIS K6721. (3) CPA (Cold Plasticizer Absorption) According to the method described in ASTM-D3367-75, 2
The absorption amount of dioctyl phthalate at 3 ° C. was measured. (4) Scale Adhesion After the polymer slurry was taken out of the polymerization tank, the state of scale adhesion in the polymerization tank was visually observed and evaluated according to the following criteria. ：: Almost no adhesion of polymer scale △: White polymer scale can be confirmed on the inner wall of the polymerization tank ×: Many white polymer scale can be confirmed on the inner wall of the polymerization tank (5) Colorability at the time of heat treatment Vinyl chloride After heat-treating the polymer at 140 ° C. for 10 minutes in an air atmosphere, the degree of coloring of the vinyl chloride polymer was visually observed and evaluated according to the following criteria. ：: No change △: Slight yellow color ×: Yellow color

Example 1 (Production of PVA-based polymer) 38.1 kg of vinyl acetate and 21.8 kg of methanol were placed in a 100-L pressure reactor equipped with a stirrer, a nitrogen inlet, an ethylene inlet and an initiator inlet.
Was heated to 60 ° C., and then the system was purged with nitrogen by bubbling nitrogen for 30 minutes. Then, the reaction tank pressure was 0.1
Ethylene was introduced and charged to be 0 MPa. 2,2′-azobis (4-methoxy-2,4-
A solution of dimethylvaleronitrile) in methanol was prepared at a concentration of 2.8 g / L, followed by bubbling with nitrogen gas and purging with nitrogen. After adjusting the inside temperature of the reaction vessel to 60 ° C., 32 mL of the above-described initiator solution was injected to initiate polymerization. During the polymerization, ethylene was introduced to maintain the reactor pressure at 0.10 MPa and the polymerization temperature at 60 ° C., and the above-mentioned initiator solution was continuously added at 102 mL / hr. After 5 hours, when the conversion reached 50%, the mixture was cooled to stop the polymerization. After the reaction vessel was opened to remove ethylene, nitrogen gas was bubbled through to completely remove ethylene. Next, unreacted vinyl acetate monomer was removed under reduced pressure to obtain a methanol solution of a PVAc polymer. A NaOH methanol solution (10% concentration) was added to the solution adjusted to 30% so that the alkali molar ratio (moles of NaOH / moles of vinyl ester units in the PVAc polymer) was 0.006. Saponified. After the saponification reaction, the solid content of the reaction solution is pulverized, centrifuged, and dried at 60 ° C. under reduced pressure.
A VA polymer was obtained. The degree of saponification of the PVA-based polymer was measured in accordance with JIS K6726 of a conventional method, and was found to be 85 mol%.

After the polymerization, the unreacted vinyl acetate monomer was removed, and a methanol solution of the PVAc polymer obtained was poured into n-hexane to precipitate the PVAc polymer, and the recovered PVAc polymer was washed with acetone. Reprecipitation purification in 3
After repeated, drying was performed at 60 ° C. under reduced pressure to obtain a purified PVAc polymer. The ethylene unit content of the PVAc-based polymer determined by proton NMR measurement was 2 mol%. Further, after saponifying the methanol solution of the above-mentioned PVAc polymer at an alkali molar ratio of 0.2, Soxhlet extraction with methanol was performed for 3 days, followed by drying to obtain P
A purified product of the VA polymer was obtained. The average degree of polymerization of the PVA-based polymer was 1000 according to a conventional method measured according to JIS K6726. By the above operation, the polymerization degree is 100
0, P having a degree of saponification of 85 mol% and an ethylene content of 2 mol%
A VA polymer (A) was obtained. Hereinafter, this is referred to as PVA-based polymer (A-1).

The degree of polymerization of the polymer obtained by the above operation is changed by changing the weight ratio of methanol to a monomer such as vinyl acetate in the polymerization operation, and the pressure of ethylene in the reaction vessel is changed. Thus, the ethylene content of the polymer can be changed, and the saponification degree of the polymer can be changed by changing the alkali molar ratio in the saponification operation. In the above operation, ethylene was not used at the time of polymerization, and the weight ratio of monomer / methanol was changed.
By changing the alkali molar ratio during saponification, a PVA-based polymer (B) having a degree of polymerization of 250 and a degree of saponification of 40 mol% was obtained. Hereinafter, this is referred to as PVA-based polymer (B-1).

(Polymerization of Vinyl Chloride) In a glass-lined autoclave, 40 parts of deionized water in which a dispersion stabilizer shown in Table 1 was dissolved and 0.04 part of a 70% toluene solution of diisopropyl peroxydicarbonate were charged.
After the inside of the autoclave was degassed until the pressure became 0.0067 MPa to remove oxygen, 30 parts of a vinyl chloride monomer was charged, and the temperature was raised to 57 ° C. with stirring to carry out polymerization. At the start of the polymerization, the pressure in the autoclave was 0.83 MPa, but when the pressure reached 0.49 MPa 6 hours after the start of the polymerization, the polymerization was stopped, and the unreacted vinyl chloride monomer was purged.
The contents were taken out and dehydrated and dried. The polymerization yield of the vinyl chloride polymer was 85%, and the average degree of polymerization was 1,050. The polymerizability and properties of the vinyl chloride polymer were evaluated by the methods described above. Table 2 shows the evaluation results.

Examples 2 and 3 (Polymerization of vinyl chloride) In Example 1, the PVA polymer (A-1) was used as the PVA polymer (A), and the PVA polymer (B) was used as the PVA polymer (B). B-1) was used as the dispersion stabilizer, and as shown in Table 1, the amount of the PVA-based polymer (A) used and the weight ratio (A) of the PVA-based polymer (A) to the PVA-based polymer (B) Example 1 except that () / (B) was changed.
The suspension polymerization of vinyl chloride was carried out in the same manner as described above to evaluate the polymerizability and the properties of the vinyl chloride polymer.
Table 2 shows the evaluation results.

Examples 4 and 5 (Production of PVA-based polymer) In Example 1, the weight ratio of monomer / methanol and the pressure of ethylene in the reactor were changed during polymerization, and the alkali molar ratio was changed during saponification. Thus, a PVA-based polymer (A) having a degree of polymerization of 1700, a degree of saponification of 88 mol%, and an ethylene content of 5 mol% was obtained. Hereinafter, this is referred to as PVA-based polymer (A-2).

(Polymerization of vinyl chloride)
As the PVA-based polymer (A), a PVA-based polymer (A-
2) PVA-based polymer (B) as PVA-based polymer (B)
-1) as a dispersion stabilizer, and PVA as shown in Table 1.
Used amount of PVA-based polymer (A) and PVA-based polymer (A)
A suspension polymerization of vinyl chloride was carried out in the same manner as in Example 1 except that the weight ratio (A) / (B) of the polymer and the PVA-based polymer (B) was changed. Was evaluated. Table 2 shows the evaluation results.

Example 6 (Production of PVA-based polymer) In Example 1, the weight ratio of monomer / methanol and the pressure of ethylene in the reactor were changed during polymerization, and the alkali molar ratio was changed during saponification. A PVA polymer (A) having a degree of polymerization of 700, a degree of saponification of 70 mol%, and an ethylene content of 1.5 mol% was obtained. Hereinafter, this is referred to as PVA-based polymer (A-3). In addition, ethylene was not used at the time of polymerization, and the weight ratio of monomer / methanol was changed.
00, a PVA-based polymer (B) having a saponification degree of 55 mol% was obtained. Hereinafter, this is referred to as PVA-based polymer (B-2).

(Polymerization of Vinyl Chloride) In Example 1,
As the PVA-based polymer (A), a PVA-based polymer (A-
3) PVA-based polymer (B) as PVA-based polymer (B)
-2) as a dispersion stabilizer, and as shown in Table 1, PVA
Weight ratio of polymer (A) to PVA polymer (B) (A)
A suspension polymerization of vinyl chloride was carried out in the same manner as in Example 1 except that / (B) was changed, and the polymerizability and the properties of the vinyl chloride polymer were evaluated. Table 2 shows the evaluation results.

Example 7 (Production of a PVA-based polymer containing a carboxyl group in the side chain) 21.0 kg of vinyl acetate was placed in a 100 L reaction tank equipped with a stirrer, a nitrogen inlet, a reflux condenser and an additive inlet.
After charging 38.9 kg of methanol and raising the temperature to 60 ° C., the system was purged with nitrogen by bubbling nitrogen for 30 minutes. A 10% concentration solution of itaconic acid dissolved in methanol as a comonomer was prepared, and the atmosphere was replaced with nitrogen by bubbling with nitrogen gas. Adjust the temperature inside the reactor to 60 ° C,
After adding 9.4 g of itaconic acid, 50 g of 2,2'-azobis (isobutyronitrile) was added to initiate polymerization. During the polymerization, the polymerization temperature was maintained at 60 ° C., and a 10% methanol solution of itaconic acid was continuously added at 600 mL / hr. After 5 hours, when the conversion reached 65%, the system was cooled to stop the polymerization. Next, unreacted vinyl acetate monomer was removed under reduced pressure to obtain a methanol solution of a PVAc polymer. An alkali molar ratio (NaO) was added to the solution adjusted to 30%.
A NaOH methanol solution (10% concentration) was added so that the molar number of H / the molar number of vinyl ester units in the PVAc-based polymer) was 0.002, followed by saponification. After the saponification reaction, the solid content in the reaction solution was pulverized, then subjected to centrifugal elimination, and dried under reduced pressure at 60 ° C. to obtain a PVA-based polymer. The P
The degree of saponification of the VA polymer was 40 mol% as measured according to JIS K6726 in a conventional manner.

After polymerization, a methanol solution of a PVAc polymer obtained by removing unreacted vinyl acetate monomer was poured into n-hexane to precipitate the PVAc polymer, and the recovered PVAc polymer was washed with acetone. Reprecipitation purification in 3
After repeated, drying was performed at 60 ° C. under reduced pressure to obtain a purified PVAc polymer. The content of itaconic acid units determined by proton NMR measurement of the PVAc polymer was 1 mol%. Further, after saponifying the methanol solution of the above-mentioned PVAc polymer at an alkali molar ratio of 0.2, Soxhlet extraction with methanol was performed for 3 days, followed by drying to obtain P
A purified product of the VA polymer was obtained. The average degree of polymerization of the PVA-based polymer was 400 when measured according to JIS K6726 of a conventional method.

By the above operation, the degree of polymerization was 400 and the degree of saponification was 4
At 0 mol%, a PVA polymer (B) containing a carboxyl group as an ionic group in the side chain was obtained. Hereinafter, this is referred to as an ion-modified PVA-based polymer (B-3).

(Polymerization of Vinyl Chloride)
As the PVA-based polymer (A), a PVA-based polymer (A-
2), except that the ion-modified PVA-based polymer (B-3) was used as the dispersion stabilizer as the PVA-based polymer (B), and the weight ratio (A) / (B) was changed as shown in Table 1. The suspension polymerization of vinyl chloride was carried out in the same manner as in Example 1 to evaluate the polymerizability and the properties of the vinyl chloride polymer. Table 2 shows the evaluation results.

Example 8 (Production of a PVA-based polymer containing a carboxyl group at a terminal) Vinyl acetate 49.7 k was placed in a 100 L reaction tank equipped with a stirrer, a nitrogen inlet, an additive inlet, and an initiator inlet.
g of methanol and 12.3 kg of methanol, the temperature was raised to 60 ° C., and the system was purged with nitrogen for 30 minutes by nitrogen bubbling. A 10% concentration solution of 3-mercaptopropionic acid (hereinafter, referred to as 3-MPA) dissolved in methanol as a chain transfer agent was prepared, and nitrogen was replaced by bubbling with nitrogen gas. After adjusting the internal temperature of the reaction vessel to 60 ° C. and adding 4.2 g of 3-MPA, 20 g of 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile) was added to initiate polymerization. . During the polymerization, the polymerization temperature was maintained at 60 ° C., and a 10% methanol solution of 3-MPA was continuously added at 230 mL / hr. After 4 hours, when the conversion reached 65%, the system was cooled to stop the polymerization. Then, unreacted vinyl acetate monomer was removed under reduced pressure, and PVA was removed.
A methanol solution of the c-based polymer was obtained. An alkali molar ratio (moles of NaOH / PVAc) was added to the solution adjusted to 30%.
(Moles of vinyl ester units in the system polymer) is 0.00
2 NaOH methanol solution (10% concentration)
And saponified. After the saponification reaction, the solid content in the reaction solution was pulverized, then subjected to centrifugal elimination, and dried under reduced pressure at 60 ° C. to obtain a PVA-based polymer. The degree of saponification of the PVA-based polymer was 40 mol% as measured according to a conventional method JIS K6726.

After the polymerization, the unreacted vinyl acetate monomer was removed, and a methanol solution of the PVAc polymer obtained was poured into n-hexane to precipitate the PVAc polymer, and the recovered PVAc polymer was washed with acetone. Reprecipitation purification in 3
After repeated, drying was performed at 60 ° C. under reduced pressure to obtain a purified PVAc polymer. Further, after saponifying the methanol solution of the above-mentioned PVAc polymer at an alkali molar ratio of 0.2, Soxhlet extraction with methanol was carried out for 3 days, followed by drying to obtain a purified PVA polymer. The average degree of polymerization of the PVA-based polymer was 350 in accordance with a standard method of JIS K6726.

By the above operation, the degree of polymerization was 350 and the degree of saponification was 4
At 0 mol%, a PVA-based polymer (B) containing a carboxyl group as an ionic group at the terminal was obtained. Hereinafter, this is referred to as a terminal ion-modified PVA-based polymer (B-4).

(Polymerization of Vinyl Chloride)
As the PVA-based polymer (A), a PVA-based polymer (A-
3) as a PVA-based polymer (B), terminal ion-modified PV
Example 1 except that the A-based polymer (B-4) was used as a dispersion stabilizer and the weight ratio (A) / (B) was changed as shown in Table 1.
The suspension polymerization of vinyl chloride was carried out in the same manner as described above to evaluate the polymerizability and the properties of the vinyl chloride polymer.
Table 2 shows the evaluation results.

Comparative Example 1 (Production of PVA-based polymer) In Example 1, the polymerization was changed so that ethylene was not used, and a PVA-based polymer having a polymerization degree of 1000 and a saponification degree of 85 mol% was obtained. Hereinafter, this is referred to as PVA-based polymer (a-1).

(Polymerization of vinyl chloride)
Instead of the PVA-based polymer (A), the PVA-based polymer (a-
1) As a PVA-based polymer (B), a PVA-based polymer (B
A suspension polymerization of vinyl chloride was carried out in the same manner as in Example 1 except that -1) was used as a dispersion stabilizer, and the polymerizability was evaluated. Since the obtained vinyl chloride polymer was blocked in the reaction tank, its properties were not evaluated. Table 2 shows the evaluation results.

Comparative Example 2 (Polymerization of Vinyl Chloride) In Example 1, PVA polymer (A-1) was used as the PVA polymer (A) as a dispersion stabilizer, and PVA polymer (B) was used. Otherwise, suspension polymerization of vinyl chloride was carried out in the same manner as in Example 1 to evaluate the polymerizability and the properties of the vinyl chloride polymer. Table 2 shows the evaluation results.

Comparative Example 3 (Production of PVA-based polymer) In Example 1, the polymerization ratio was changed by changing the weight ratio of monomer / methanol and changing the alkali molar ratio during saponification without using ethylene during the polymerization. 17
A PVA polymer having a saponification degree of 88 mol% was obtained. Hereinafter, this is referred to as PVA-based polymer (a-2).

(Polymerization of Vinyl Chloride)
Instead of the PVA-based polymer (A), the PVA-based polymer (a-
2) PVA-based polymer (B) as PVA-based polymer (B)
-1) was used as the dispersion stabilizer, and as shown in Table 1, the weight ratio (A) / (B) {here, the weight ratio (a-2) / (B-
1) Except that｝ was changed, the same procedure as in Example 1 was carried out to carry out suspension polymerization of vinyl chloride, and to evaluate the polymerizability and the properties of the vinyl chloride polymer. Table 2 shows the evaluation results.

Comparative Example 4 (Production of PVA-based polymer) In Example 1, the polymerization ratio was changed by changing the monomer / methanol weight ratio and changing the alkali molar ratio during saponification without using ethylene during the polymerization. 70
Thus, a PVA polymer having a saponification degree of 70 mol% was obtained. Hereinafter, this is referred to as PVA-based polymer (a-3).

(Polymerization of Vinyl Chloride)
Instead of the PVA-based polymer (A), the PVA-based polymer (a-
3) PVA-based polymer (B) as PVA-based polymer (B)
-2) was used as the dispersion stabilizer, and as shown in Table 1, the weight ratio (A) / (B) {here, the weight ratio (a-3) / (B-
2) Suspension polymerization of vinyl chloride was carried out in the same manner as in Example 1 except that｝ was changed, and the polymerizability was evaluated. Because the obtained vinyl chloride polymer was blocked in the reaction tank,
The properties were not evaluated. Table 2 shows the evaluation results.

[0058]

[Table 1]

[0059]

[Table 2]

Example 9 (Production of PVA-based polymer)
After the saponification reaction of the PVA-based polymer, the obtained PVA-based polymer is
The same operation as in Example 1 was performed except that the polymer was washed at 25 ° C. with 30 times the amount of PVA-based polymer on a weight basis, dried at 60 ° C. under reduced pressure, and then heat-treated at 150 ° C. for 2 hours in air. Thus, a PVA polymer (A) having a degree of polymerization of 1,000, a degree of saponification of 85 mol%, and an ethylene content of 2 mol% was obtained. Hereinafter, this is referred to as PVA-based polymer (A-4). PVA
When the system polymer (A-4) was analyzed by an electrophoresis method, the content of sodium acetate per 100 parts by weight of the PVA polymer was 0.7 part by weight. No coloring was observed in the heat-treated PVA-based polymer (A-4).

(Polymerization of Vinyl Chloride) In a glass-lined autoclave, 40 parts of deionized water in which a PVA polymer shown in Table 3 was dissolved and 0.016 part of a 70% toluene solution of diisopropyl peroxydicarbonate were charged. After the inside of the autoclave was degassed until the pressure became 0.0067 MPa to remove oxygen, 30 parts of a vinyl chloride monomer was charged, and the temperature was raised to 65 ° C. with stirring to carry out polymerization. At the start of the polymerization, the pressure in the autoclave was 1.08 MPa, but when the pressure reached 0.44 MPa 6 hours after the start of the polymerization, the polymerization was stopped, the unreacted vinyl chloride monomer was purged, and the content was purged. It was taken out and dehydrated and dried. The scale adhesion and the colorability of the vinyl chloride polymer during heat treatment were evaluated by the above-described methods. Table 3 shows the evaluation results.

Comparative Example 5 (Production of PVA-based polymer)
After the saponification reaction of the PVA-based polymer, the obtained PVA-based polymer is
Analyze by electrophoresis until the sodium acetate content per 100 parts by weight of the PVA-based polymer becomes 0.02 parts by weight. Repeat the washing operation with
After drying under reduced pressure at 150 ° C., the same operation as in Example 1 was carried out except that heat treatment was performed at 150 ° C. for 2 hours in air.
0, P having a degree of saponification of 85 mol% and an ethylene content of 2 mol%
A VA polymer (A) was obtained. Hereinafter, this is referred to as PVA-based polymer (A-5). When the PVA-based polymer (A-5) was analyzed by an electrophoresis method, the PVA-based polymer (A-5) was analyzed.
The content of sodium acetate per 0 parts by weight was 0.02 parts by weight. No coloring was observed in the heat-treated PVA-based polymer (A-5).

(Polymerization of Vinyl Chloride)
The suspension polymerization of vinyl chloride was carried out in the same manner as in Example 9 except that the PVA-based polymer (A-5) was used instead of the PVA-based polymer (A-4), and the scale adhesion and vinyl chloride were obtained. The colorability of the polymer during heat treatment was evaluated. Table 3 shows the evaluation results.

Comparative Example 6 (Production of PVA-based polymer)
PVAc adjusted to 30% during the saponification reaction of the polymer
The methanol solution of the polymer is mixed with an alkali molar ratio (NaO
A methanol solution of NaOH (10% concentration) was added so that the molar number of H / the molar number of vinyl ester units in the PVAc polymer became 0.006, and further, 0.3 kg of sodium acetate was added to saponify. After drying under reduced pressure at 60 ° C., the obtained PVA-based polymer was heat-treated at 150 ° C. for 2 hours in air, and operated in the same manner as in Example 1 to obtain a polymerization degree of 1000, a saponification degree of 85 mol%, and ethylene. A PVA-based polymer (A) having a content of 2 mol% was obtained. Hereinafter, this is referred to as PVA
This is referred to as a polymer (A-6). PVA-based polymer (A-
When 6) was analyzed by an electrophoresis method, the content of sodium acetate per 100 parts by weight of the PVA-based polymer was 2.5 parts by weight. In addition, the heat-treated PV
The A-based polymer (A-6) was colored red-brown.

(Polymerization of Vinyl Chloride)
Suspension polymerization of vinyl chloride was carried out in the same manner as in Example 9 except that the PVA-based polymer (A-6) was used instead of the PVA-based polymer (A-4) to obtain scale adhesion and vinyl chloride. The colorability of the polymer during heat treatment was evaluated. Table 3 shows the evaluation results.

[0066]

[Table 3]

[0067]

EFFECT OF THE INVENTION The dispersion stabilizer for suspension polymerization of vinyl compounds of the present invention is remarkably excellent in suspension polymerization stability when used in a small amount, and is used for the suspension polymerization of vinyl compounds. By doing so, the polymer particles have a sharp particle size distribution, have less scattering during handling, have good penetration into molding machines, etc., have a high plasticizer absorption rate and are excellent in processability, and polymer particles. It is possible to produce a vinyl polymer with characteristics such as easy removal of monomers remaining in the inside, low fisheye in the molded article due to the porous nature of the polymer particles, and high bulk specific gravity. Its industrial reputation is extremely high because it can be done.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J002 BD031 BE021 BE022 BE031 BE032 EG026 EG076 4J011 AA08 EA06 JA06 JA07

Claims (9)

[Claims] 1. An ethylene unit content of 0.5 to 20 mol%, a saponification degree of 60 mol% or more, and a polymerization degree of 600
A dispersion stabilizer for suspension polymerization of a vinyl compound comprising the above vinyl alcohol polymer (A) and a vinyl alcohol polymer (B) having a saponification degree of 20 to 60 mol% and a polymerization degree of 100 to 600. 2. The method according to claim 1, wherein the difference in the degree of saponification between the vinyl alcohol-based polymer (A) and the vinyl alcohol-based polymer (B) is 15 mol% or more and / or the difference in the degree of polymerization is 200 or more. A dispersion stabilizer for suspension polymerization of vinyl compounds. 3. A method according to claim 1, wherein the vinyl alcohol polymer (A) and the vinyl alcohol polymer (B) are the components (A) / (B)
The dispersion stabilizer for suspension polymerization according to claim 1, wherein the component is contained in a weight ratio of 95/5 to 20/80. 4. The suspension according to claim 1, wherein the vinyl alcohol polymer (B) is a water-soluble or water-dispersible polymer having a sulfonic acid group, an amino group, an ammonium group, a carboxyl group or a cationic group. Dispersion stabilizer for polymerization. 5. The method according to claim 1, wherein the vinyl alcohol polymer (A) is heat-treated at 100 to 200 ° C. for 0.5 to 20 hours in an atmosphere of oxygen, air or nitrogen. A dispersion stabilizer for suspension polymerization. 6. A vinyl alcohol polymer (A) 100
Acid having a pKa of 3.5 to 5.5 and / or
The dispersion stabilizer for suspension polymerization according to claim 5, wherein the metal salt (C) is contained in an amount of 0.05 to 2 parts by weight. 7. The dispersion for suspension polymerization according to claim 1, wherein the amount of the dispersion stabilizer for suspension polymerization is 0.01 to 5 parts by weight based on 100 parts by weight of the vinyl compound. Stabilizer. 8. The dispersion stabilizer for suspension polymerization according to claim 1, wherein the vinyl compound is vinyl chloride. 9. A suspension polymerization method for a vinyl compound, which is carried out in the presence of the dispersion stabilizer for suspension polymerization according to claim 1.