JP2756995B2 - Method for producing vinyl chloride copolymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Object of the Invention (Field of Industrial Application) The present invention relates to a method for producing a vinyl chloride copolymer having good productivity and good reaction control.

(Prior art) Conventionally, a vinyl chloride copolymer for pastes is usually used in the same manner as in a vinyl chloride homopolymer for general pastes.
An emulsion polymerization method using a water-soluble polymerization initiator, or a mixture of a vinyl chloride monomer and a monomer copolymerizable therewith (hereinafter, this may be referred to as a "vinyl chloride-based monomer mixture"). A fine suspension polymerization method in which polymerization is carried out using a so-called oil-soluble polymerization initiator that dissolves in water, and after mechanically dispersing a vinyl chloride-based monomer mixture uniformly and finely in water (after homogenization treatment). It is manufactured by.

The vinyl chloride copolymer for pastes obtained by such a production method includes, for example, a plasticizer, a diluent, a stabilizer, and, depending on the application, a thermal decomposition type organic foaming agent and lowers the decomposition temperature of the foaming agent. A foaming aid called "kicker" and other additives are added and mixed or kneaded, and then gelled to produce a large amount to produce flooring materials, wall materials, ceiling covering materials, leather, sealing agents, etc. Used in

In particular, when used as a sealant for automobiles or as a rust-proof coating under a body, gelation and melting are fast due to low temperature and high speed of the construction, and mechanical properties after application ( Copolymers having good breaking strength and breaking elongation, particularly copolymers with vinyl acetate, have been awarded. In addition, since the vinyl chloride copolymer can be processed at low temperatures, the backing material of carpet tiles often used for floors equipped with OA equipment can be processed at low temperatures, so there is little damage to the fiber layer on the surface.
May be used.

Vinyl chloride copolymers used for these applications are:
As described above, it is often produced by a method exactly the same as the method for producing a vinyl chloride homopolymer, but the polymerization rate of the polymerization reaction (accordingly, the polymerization reaction time) varies,
The controllability of the particle diameter of the formed resin was poor, and no method that can be produced industrially advantageously was found. That is, in the conventional method for producing this kind of copolymer, the polymerization reaction rate is low and satisfactory productivity cannot be obtained, or conversely, only a polymer having an irregular particle size due to a runaway polymerization reaction or the like can be obtained. Alternatively, there are drawbacks such as a low polymerization yield and a low polymer yield.

(Problems of the Invention) An object of the present invention is to provide a method for producing a vinyl chloride copolymer having high productivity and good reaction controllability.

(B) Configuration of the Invention (Means for Solving the Problems) As a result of various studies for solving the above problems, the present inventors have found that the above-mentioned emulsion polymerization or micronization for producing a vinyl chloride-based copolymer is carried out. By continuously adding water-soluble transition metal salts to the suspension polymerization reaction system for a certain period of time during the polymerization reaction, the polymerization reaction speed can be increased, and abnormal polymerization reactions such as runaway reactions can be prevented. It has been found that a good quality copolymer can be produced in a high reaction yield in a long time, and the present invention has been completed.

That is, the method for producing a vinyl chloride-based copolymer of the present invention is a method in which a mixture of a vinyl chloride monomer and a monomer copolymerizable therewith is subjected to emulsion polymerization or fine suspension polymerization. This is a method characterized by continuously adding a water-soluble transition metal salt to the system for a certain period of time.

The “continuous addition” in the continuous addition of the water-soluble transition metal salt described in the present specification includes, in addition to the continuous addition in the ordinary sense, an addition in which intermittent addition is continuously repeated at short time intervals. Is also included.

Examples of the monomer to be copolymerized with the vinyl chloride monomer in the method for producing a vinyl chloride copolymer of the present invention include olefins such as ethylene, propylene, n-butene, vinyl acetate, vinyl propionate, and the like. Vinyl esters such as vinyl stearate, unsaturated acids such as acrylic acid, methacrylic acid, itaconic acid, alkyl esters of these unsaturated acids, methyl vinyl ether, ethyl vinyl ether, octyl vinyl ether, lauryl vinyl ether, etc. Such vinyl ethers, maleic acid, any unsaturated dibasic acids such as fumaric acid, acid anhydrides such as maleic anhydride, alkyl esters of these unsaturated dibasic acids,
Examples include various unsaturated nitrites, and mixtures of two or more of these various monomers. Among these monomers to be copolymerized, vinyl acetate has a modifying effect on a produced copolymer, compatibility with a vinyl chloride monomer, compatibility with a vinyl chloride resin, and a plasticizer for the produced copolymer. It is particularly preferable in terms of compatibility with the like. The copolymerization amount of these monomers to be copolymerized is 30% by weight or less of the copolymer, preferably 20% by weight.
% By weight or less.

As the polymerization initiator used in the production method of the present invention,
For example, water-soluble peroxides such as persulfates (sodium salts, potassium salts, ammonium salts, etc.), hydrogen peroxide and the like, these persulfates and water-soluble peroxides, and sodium sulfite, ammonium sulfite, sodium hydrogen sulfite, ascorbin Acid, water-soluble redox initiator comprising a reducing agent such as formaldehyde sodium sulfoxylate, azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile, lauroyl peroxide, t-butyl peroxypivalate, etc. Monomer-soluble (oil-soluble) initiators,
And an initiator comprising a combination of these monomer-soluble initiators and the above-mentioned reducing agent for a redox initiator.

As the emulsifier used in the production method of the present invention, for example, alkali metal sulfates of higher alcohols, ammonium salts thereof, alkali metal salts of alkylbenzenesulfonic acid, ammonium salts, alkali metal salts of higher fatty acids,
An emulsifier such as the same ammonium salt may be used. One of these emulsifiers may be used, or two or more thereof may be used in combination. The amount of the emulsifier used is 0.1 to 3.0% by weight, preferably 0.3 to 1.0% by weight, based on the vinyl chloride monomer mixture.

The water-soluble transition metal salt used in the production method of the present invention is preferably a metal whose metal element belongs to Group Ib or Group VIII of the periodic table, and more preferably a metal belonging to column 4 of the periodic table. Are preferred. Preferred specific examples of the water-soluble transition metal salts that can be used include, for example, cupric chloride, ferric sulfate, and nickel nitrate. The amount of the water-soluble transition metal salt added is the total amount of the metal added to the amount of the charged monomer.
It is 0.05 to 100 ppm by weight, preferably 0.1 to 50 ppm by weight.
If the addition amount is too small, a sufficient reaction control effect cannot be obtained, and if it is too large, the hue and thermal stability of the final product of the obtained copolymer may be impaired.

The addition of the water-soluble transition metal salt in the production method of the present invention is a method of continuously adding the water-soluble transition metal salt to the polymerization reaction system for a certain period during the polymerization reaction. This is a method in which the addition is continuously performed until the reaction exceeds about 80% immediately after the start of the polymerization reaction, or until the liquid chloride and vinyl monomer disappear.

Further, in the production method of the present invention, a part of the water-soluble transition metal salts, at any time before the start of polymerization, for example, water,
It can be added all at once or before or after the monomer is charged, or simultaneously with or after the emulsifier, polymerization initiator or other polymerization aids. As described above, by adding a part of the water-soluble transition metal salts before the start of the polymerization, the reactivity at the initial stage of the polymerization can be increased, and the polymerization reaction can be smoothly started. However, also in this case, of course, the rest (main part) of the water-soluble transition metal salt is continuously added to the reaction system during the polymerization reaction for a certain period.

Since the addition amount of the water-soluble transition metal salt in the present invention is very small, it is preferable to add the water-soluble transition metal salt in the form of an aqueous solution in which it is dissolved in water, in order to uniformly distribute the salt in the reaction system. Further, a method of mixing and adding with other polymerization aids and the like which are continuously added to the reaction system can also be used as long as the water-soluble transition metal salts and the aids do not react to form a precipitate or the like.

In the present invention, the reason why the addition of the water-soluble transition metal salt provides a reaction control effect such as the promotion of the polymerization reaction is not necessarily clear, but the efficiency of radical generation by redox, and the trace amount contained in the copolymerized monomer are not clear. It is presumed that this is due to the elimination of the adverse effects of the polymerization inhibitor. The reason why the continuous addition is particularly effective is that, for example, in the case of simultaneous addition at the beginning, these salts are consumed by radicals at the beginning of the reaction, or the oligomer generated during the polymerization reaction is The transition metal is surrounded and inactivated as if it is coordinated, but it is presumed that such adverse effects could be eliminated by continuous addition.

When producing the vinyl chloride copolymer of the present invention, various auxiliaries, modifiers and the like used in the production of general vinyl chloride polymers for pastes can be used (added).

Further, the vinyl chloride copolymer obtained by the production method of the present invention is particularly suitable as a resin for paste. That is, the vinyl chloride copolymer is added with a plasticizer, a stabilizer, and other various additives (for example, an antioxidant, an ultraviolet absorber, a filler, an antistatic agent, a colorant,
Release agent) is advantageously used as a plastisol or organosol.

Examples of the plasticizer include di-n-butyl phthalate, di-n-octyl phthalate, di-2-ethylhexyl phthalate, diisooctyl phthalate, diisononyl phthalate, diisodecyl phthalate, octyl decyl phthalate, and butyl benzyl phthalate Phthalic acid plasticizers such as di-2-ethylhexyl isophthalate, phthalic acid esters of higher alcohols having about 11 to 13 carbon atoms, di-n-octyl-n-decyl trimellitate, and tri-mellitate
2-ethylhexyl, triisodecyl trimellitate,
Trimellitic acid plasticizers such as tri-n-octyl trimellitate, di-2-ethylhexyl adipate, di-n-decyl adipate, diisodecyl adipate, di-2-ethylhexyl azelate, dibutyl sebacate,
Fatty acid ester plasticizers such as di-2-ethylhexyl sebacate, phosphate plasticizers such as tributyl phosphate, tri-2-ethylhexyl phosphate, 2-ethylhexyl diphenyl phosphate and tricresyl phosphate, epoxidation Epoxy plasticizers such as soybean oil, epoxidized linseed oil, epoxidized tall oil fatty acid-2-ethylhexyl, and liquid epoxy resorcinol. One type of these plasticizers may be used, or two or more types may be used in combination.

Examples of the stabilizer include known lead-based, barium-zinc-based, calcium-zinc-based, and magnesium-based.
Zinc-based, calcium-barium-based, cadmium-barium-based, barium-zinc-tin-based, cadmium-barium-zinc-based, organic tin-based, and other various stabilizers can be used. The amount of these stabilizers is 0.1 to 5.0 parts by weight, preferably 0.15 to 3.0 parts by weight, based on 100 parts by weight of the paste resin.

(Examples, etc.) Hereinafter, the seed polymer preparation, examples and comparative examples will be described in more detail. "%" Described in these examples is based on weight.

Seed Polymer Preparation Example 1 A 200 kg polymerization tank equipped with a stirrer was charged with 90 kg of temperature 54.
C., deionized water, 10 g potassium persulfate, and 50 g sodium pyrosulfite were added and stirred for about 20 minutes to dissolve.
Next, the pressure in the polymerization tank was reduced to −610 mm Hg, and the temperature was maintained at 55 ° C. for 50 minutes.

Next, 60 kg of vinyl chloride monomer was charged into the polymerization tank,
The temperature in the tank was raised to 50 ° C. Fifteen minutes after the monomer was charged, a 0.2% aqueous potassium persulfate solution which had been previously dissolved was gradually added at a rate of about 10 cc / min. The reaction is performed while controlling the addition rate of the potassium solution, and when the polymerization rate reaches about 15%,
The addition of the separately dissolved aqueous sodium lauryl sulfate solution was started, and the aqueous solution was added at a rate of about 80 cc / 10 minutes until the added amount of sodium lauryl sulfate reached 360 g. The reaction was stopped when the pressure in the tank dropped 2.0 kg / cm ² from the saturation pressure of the vinyl chloride monomer at 50 ° C., and the unreacted monomer was recovered to obtain a polymer latex.

The obtained latex was monodispersed particles having a particle size of about 0.48 μm, and the stability of the latex was good.

Example 1 80 k of water was used for deionization in a polymerization tank having a capacity of 200 with a stirrer.
g, 4.5 kg of the seed polymer latex obtained in Preparation Example 1 above
(Solid content), 70 g of sodium pyrosulfite, and 0.03
After degassing after charging 150 g of a 2% aqueous cupric chloride solution, 16.5 kg of vinyl chloride monomer and vinyl acetate monomer
4.0 kg was charged and the temperature was raised to 50 ° C. Thereafter, a total amount of 15 g of a 0.1% aqueous solution of ammonium persulfate 10 was initially added at a rate of 10 cc / min for 15 minutes, and then added continuously while controlling the addition rate so as to maintain a constant polymerization rate. . Simultaneously with the start of the addition of the aqueous solution of ammonium persulfate, the continuous addition of a solution of 1 g of ferric chloride (hexahydrate) in water at a rate of 15 cc / min was started. From the time the polymerization rate reaches 10% to the end of the polymerization, a total of 0.5 kg of a 10% aqueous solution of sodium lauryl sulfate at a rate of about 0.7 / hr as sodium lauryl sulfate and a rate of 7 kg / hr of a vinyl chloride monomer are used. , A total of 35 kg were continuously added. The point at which the pressure in the reaction vessel dropped 1.0 kg / cm ² from the saturation pressure of the vinyl chloride monomer at 50 ° C. was determined as the completion point of the polymerization. 7 hours 20 from the start of heating up to the completion of polymerization
Minutes. After completion of the polymerization, unreacted monomers were recovered, and a latex having an average particle size of 0.80 μ was obtained with a reaction yield of 84%.

Comparative Example 1 Polymerization was carried out in the same manner as in Example 1 except that cupric chloride and ferric chloride were not used at all. In this case, the polymerization reaction was extremely slow, and the internal pressure of the reaction tank did not decrease even after 12 hours from the start of the reaction. The average particle size of the obtained latex was as small as 0.65 μ and the reaction rate was as low as 66%.

Comparative Example 2 Ferric chloride (1 g) was added all at once before starting the addition of the aqueous solution of ammonium persulfate, and otherwise the polymerization reaction was carried out in the same manner as in Example 1. Observation from the state of generation of reaction heat revealed that the polymerization reaction was extremely active at the beginning of the polymerization, but the reaction rate was reduced when the conversion exceeded 50%, and finally the same as in Example 1. Although a reaction yield of the order was obtained, it took 10 hours and 30 minutes to complete the reaction. The average particle size of the produced latex was as extremely small as 0.59 μm, and the particle size distribution was large and irregular. This is probably because a large amount of fine particles were generated due to rapid polymerization in the early stage of the reaction.

Seed polymer preparation example 2 100 kg of ion-exchanged water, 600 g of lauroyl peroxide, 400 g of sodium lauryl sulfate and 200 g of lauryl alcohol were added to a premixing tank having a capacity of 200 equipped with a stirrer.
Next, the premixing tank was degassed, 60 kg of vinyl chloride monomer was added, and the mixture was maintained at 35 ° C. with stirring. After stirring uniformly, the mixture was transferred to a reaction vessel having a capacity of 200 and equipped with a stirrer that had been degassed in advance while dispersing to a desired droplet diameter (about 0.6 μ) using an emulsifier (homogenizer). .

After the transfer of the dispersion was completed, the temperature of the reactor was raised to 50 ° C., and polymerization was carried out by a known method. The average diameter of the polymer particles (seed polymer particles) in the obtained latex is 0.56μ.
Met.

Example 2 80 k of deionized water was added to a polymerization tank having a volume of 200 equipped with a stirrer.
g, 5 kg of the seed polymer latex obtained in Preparation Example 2 above
(In terms of solids), 200 g of 0.05% cobaltic nitrate aqueous solution,
After degassing after charging 20 g of sodium hydrogencarbonate, charging 20 kg of vinyl chloride monomer and 5 kg of vinyl acetate monomer, 4
After the temperature was raised to 7 ° C, a 0.5% aqueous solution of sodium formaldehyde sulfoxylate, which had been dissolved in advance, was continuously added little by little to initiate polymerization. Simultaneously with the start of the addition of the aqueous sodium formaldehyde sulfoxylate solution, a total of 5 0.02% ferric chloride aqueous solution was added.
Continuous addition was started at a rate of 15 cc / min. The addition amount of the aqueous sodium formaldehyde sulfoxylate solution was adjusted so that the reaction was performed at a constant reaction rate. When the polymerization reaction rate reaches about 7-8%, the total amount
Start adding 35 kg of vinyl chloride monomer at a rate of 8 kg / hr,
Further, from the time when the polymerization rate reached 10% to the end of the polymerization, about 8% aqueous solution (total 5) of sodium dodecylbenzenesulfonate separately prepared as an emulsifier was added to 1
/ hr was continuously added. When the pressure in the polymerization tank dropped 1.5 kg / cm ² from the saturation pressure of vinyl chloride at 47 ° C., the polymerization was stopped, and unreacted monomers were recovered. The time required for the polymerization reaction was 7 hours and 50 minutes, the average particle size of the obtained latex was 1.2 μm, and the stability of the latex was good. The reaction yield was 80%.

Comparative Example 3 A polymerization reaction was started in the same manner as in Example 2 except that no cobalt nitrate and ferric chloride were used. In this case, as in Comparative Example 1, the reaction was not completed even after 12 hours from the start of the polymerization, and the reaction was terminated at this point. The average particle diameter of the obtained latex is 0.79
μ, and the reaction yield was 56%.

As is clear from the comparison between the examples and the comparative examples, by continuously adding the water-soluble transition metal salts, the polymerization reaction is effectively controlled, and the particle size is improved at a high polymerization rate (in a short time). Was produced in a high reaction yield.

(C) Effects of the Invention According to the production method of the present invention, a vinyl chloride copolymer having stable quality can be easily produced with high productivity and high reaction yield.

Claims (5)

(57) [Claims] 1. A method for emulsion polymerization or fine suspension polymerization of a mixture of a vinyl chloride monomer and a monomer copolymerizable therewith, wherein a water-soluble transition metal salt is continuously added to the reaction system during the polymerization for a certain period of time. A method for producing a vinyl chloride-based copolymer, characterized in that it is added selectively. 2. The method according to claim 1, wherein a part of the water-soluble transition metal salts is added before starting the polymerization. 3. The method according to claim 1, wherein the transition metal is a metal selected from Group Ib and Group VIII metals. 4. The method according to claim 1, wherein the transition metal is a metal in the fourth column of the periodic table. 5. The method according to any one of claims 1 to 4, wherein the monomer copolymerizable with vinyl chloride is vinyl acetate.