JPH0150242B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention produces a blending resin for polyvinyl chloride paste resin that is used together with polyvinyl chloride paste resin and has good plasticity and fluidity when made into plastisol, and has excellent quality of molded products obtained by heat molding this sol. It is related to the method. Polyvinyl chloride paste resin (hereinafter simply referred to as paste resin) is stirred and kneaded with plasticizers, secondary plasticizers, diluents, stabilizers, and other fillers to form a sol, which is then processed into a sol by dipping, slushing, rotation, and rotary screening. Alternatively, after molding by various methods such as spreading, the material is heated to gel. Therefore, for ease of molding during processing, the fluidity of the sol must be suitable for each molding method. Especially in sol molding under high shear such as spread coating,
Blending resin is often used together with paste resin to make the sol more fluid. Paste resins are generally produced by microsuspension or emulsion polymerization methods, with the former method having a polydisperse particle size distribution of 0.1μ to 3μ, and the latter method typically having a polydisperse particle size distribution of between 0.1μ and 3μ. It consists of a combination of particles with a monodisperse particle size distribution. On the other hand, blending resin, which is used as a sol fluidity improver, has a particle size larger than paste resin for that purpose, generally 20 to 80 μm.
It is desirable that the particles have an average particle size of It is used in most cases. However, in suspension polymerization, polymeric suspension stabilizers such as polyvinyl alcohol, cellulose derivatives, gelatin, etc. are generally used, so that these polymer films remain on the surface of polyvinyl chloride particles after polymerization. This film cannot be easily removed even by the dehydration and water washing treatments used in normal suspension polymerization methods, so when heat gelling plastisol containing blending resin, blending resin particles cannot be easily removed. As a result, the tensile strength and abrasion resistance of the product are impaired, which is inconvenient for applications that require particularly abrasion resistance, such as the top layer of flooring materials. Based on the above, the present inventors have conducted intensive studies to develop a blending resin that has a good effect of reducing the viscosity of plastisol and does not reduce the mechanical strength of the product, and as a result, has arrived at the present invention. That is, the present invention produces a polyvinyl chloride polymer by suspension polymerizing vinyl chloride or vinyl chloride and a monomer copolymerizable with vinyl chloride in an aqueous medium containing a polymeric suspension stabilizer using an oil-soluble catalyst. A method for producing a blending resin for polyvinyl chloride paste resin, which comprises adding an emulsifier to the polymerization system or to the obtained polymer after the start of polymerization. According to this method, it is possible to easily obtain a blending resin that has both good plastisol viscosity-lowering action and excellent mechanical strength of the product. The present invention will be explained in more detail. The monomers used for polymerization are vinyl chloride alone,
Or a mixture of vinyl chloride and a monomer that can be copolymerized with these, and the copolymerizable monomer is not particularly limited, but vinyl acetate,
Vinyl monomers such as vinyl propionate and styrene; acrylic acid, methacrylic acid and their esters; unsaturated dicarboxylic acids and their esters such as maleic acid, maleic esters, fumaric acid and fumaric esters; vinyl fluoride - Vinylidene halides other than chlorine such as vinyl bromide; vinylidene halides such as vinylidene chloride, vinylidene fluoride, and vinylidene bromide; other acrylonitrile,
All known monomers copolymerizable with vinyl chloride such as methacrylonitrile and vinyl ethers can be used. These monomers are subjected to suspension polymerization using a polymeric suspension stabilizer used in ordinary suspension polymerization of polyvinyl chloride. As a blending resin, as mentioned above, the particles are not porous but dense,
Although it is preferred to have a smooth surface, obtaining a polymer in such a form can be easily achieved by using commonly used suspension stabilizers. These suspension stabilizers include partially saponified polyvinyl alcohol, polyvinyl alcohol, methylcellulose, ethylcellulose, carboxymethylcellulose, hydroxyethylcellulose,
Cellulose derivatives such as hydroxypropylcellulose and hydroxypropylmethylcellulose; Proteins such as casein and gelatin; Copolymers of maleic anhydride and vinyl ethers and styrene;
Examples include pyrrolidone-based dispersants such as polyvinylpyrrolidone and copolymers of vinylpyrrolidone and vinyl acetate. These suspension stabilizers may be used alone, or may be used for particle size adjustment,
They may be used in combination for polymerization stabilization and other purposes. Depending on the type of suspension stabilizer, PH regulators may be added for polymerization stabilization or other purposes, higher alcohols, higher fatty acids, plasticizers, etc.
A crosslinking agent, a chain transfer agent, etc. can also be added to the polymerization system if necessary. The amount of suspension stabilizer used mainly depends on the particle size,
Settings can be made according to the conditions of each equipment using polymerization stability as a guideline, but the
0.05 to 3 parts by weight are good, and 0.1 to 2 parts by weight give particularly favorable results. Resin suspension-polymerized using an oil-soluble catalyst in an aqueous medium using such a suspension stabilizer system does not have the effects necessary for blending resins, such as plastisol viscosity reduction, even after normal dehydration and drying. However, because the polymeric suspension stabilizer film remains on the surface of the particles, the mechanical strength of processed plastisol products, such as tensile strength and abrasion resistance, is poor. As a result of intensive studies to eliminate the adverse effects of the polymer film on the particle surface, the inventors of the present invention found that by using the above-mentioned suspension stabilizer, vinyl chloride or vinyl chloride and a monomer that can be copolymerized with vinyl chloride, When producing a polyvinyl chloride polymer by polymerizing a mixture of the above, adding an emulsifier after the start of polymerization improves the plasticity during heat processing without impairing the viscosity-lowering effect of plastisol produced by blending resin. It has been found that the melting of the blending resin can be dramatically improved. The melting performance of blending resins during processing can be improved by adding various emulsifiers to the resin before the polymerization starts, but in this case, the monomers are too finely dispersed due to the action of the emulsifiers and polymerization is delayed. The viscosity-lowering effect of plastisol is unsatisfactory due to loss of stability and poor density of polymer particles after polymerization.To improve this point, reducing the amount of emulsifier used can reduce the viscosity of plastisol. Melting due to the plasticity of the combined particles deteriorates, resulting in a blending resin of unsatisfactory quality. In the present invention, the emulsifier may be added at any time as long as it does not adversely affect the formation of particles as a blending resin, such as impairing the density of the polymer particles, and after the start of polymerization, that is, when adding the emulsifier to the slurry during polymerization, It can be added to the slurry after polymerization or the wet cake after dehydration. The slurry during polymerization here refers to the slurry after the time when vinyl chloride polymer formation begins to be observed in the slurry, but if an emulsifier is added too early after the start of polymerization, the density of the particles will increase. may damage the polymerization conversion rate based on the total amount of monomer used.
Addition of 10% or more, preferably 30% or more gives good results. Another method of addition is to mix an emulsifier in an aqueous solution or the like with a dried resin, but in either case it is necessary to have the emulsifier attached to the surface of the resin particles. Any emulsifier may be used in the present invention, such as dodecylbenzenesulfonic acid, dioctylsulfosuccinic acid, lauryl sulfate,
Anionic emulsifiers such as alkali metal salts or alkaline earth metal salts of higher fatty acids are preferably used (improves the mechanical strength of the product).
However, cationic emulsifiers such as alkyltrimethylammonium chloride, alkylamine acetate, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyethylene glycol fatty acid esters, etc.
Nonionic emulsifiers such as polyethylene glycol polypropylene glycol block copolymers, sorbitan fatty acid esters, and polyoxyethylene sorbitan fatty acid esters can also be used. These can be used alone or in combination of two or more. The amount of these emulsifiers used can be selected from 0.002 to 5 parts by weight, preferably from 0.01 to 2 parts by weight, per 100 parts by weight of the total monomer charge.
If it is less than 0.002 parts by weight, the effect will not be sufficient,
If the amount is more than 5 parts by weight, the sol viscosity lowering effect may be adversely affected, which is not preferable. The polymerization initiator used in the polymerization of the present invention is not particularly limited as long as it is an oil-soluble thermally decomposable radical generator, such as lauroyl peroxide, decanoyl peroxide, 3,5,5-trimethylhexanoyl Diacyl peroxide initiators such as peroxide; Perester initiators such as t-propyl peroxyacetate and t-butyl peroxy pivalate; Peroxy initiators such as diisopropyl peroxydicarbonate and 2-ethylhexyl peroxydicarbonate Dicarbonate initiators; azo initiators such as azobisisobutyronitrile and α,α'-azobis-2,4-dimethylvaleronitrile can be mentioned. The present invention will be further explained below using Examples, but the contents of the Examples are not intended to limit the scope of the present invention. Examples 1 to 6 30 kg of water was placed in an autoclave equipped with a 50 mm propeller stirring blade, and methyl cellulose (viscosity of 2% aqueous solution at 20°C) was added as a suspension stabilizer.
50cps) dissolve 30g. After adding 11 g of α,α'-azobis-2,4-dimethylvaleronitrile, the autoclave was sealed and the oxygen in the polymerization system was evacuated. After charging 12 kg of vinyl chloride monomer, stirring was started and the temperature was raised to 58°C to start the polymerization reaction. The type and timing of the emulsifier added are shown in Table 1, and 360 g of a 10% solution of the emulsifier was added. Polymerization was continued until the polymerization pressure decreased by 2 kg/cm ² from the initial polymerization pressure, and the resulting slurry was centrifugally dehydrated, and then the resin was left to dry at 60°C. The performance of the polymer obtained by the above method as a blending resin was evaluated as follows and is shown in Table 1. (Preparation of plastisol and measurement of plastisol viscosity) 30 g of blending resin and paste resin (Kanevinyl Paste PSH-680 manufactured by Kanebuchi Chemical Industry)
70g with 50g of dioctyl phthalate as a plasticizer,
Furthermore, after adding 3 g of Ba-Zn stabilizer, the mixture was stirred and dispersed using a propeller mixer, and defoamed to prepare plastisol. The viscosity of this sol was measured using a BM type viscometer 1 hour and 3 days after the sol was prepared. (Preparation of cast film and strength test) The plastisol obtained by the above method was coated on a glass plate and heated at 200° C. for 5 minutes to prepare a film with a thickness of about 0.25 mm and 1 mm. The tensile strength (using a 0.25 mm thick film) and abrasion resistance (using a 1 mm thick film) of this film were determined by JIS K-6723 and JIS K, respectively.
Measured according to -7204. Comparative Example 1 A resin was polymerized and evaluated in the same manner as in Example, but no emulsifier was added. Comparative Example 2 The difference from Example is that 36 g of sodium dodecylbenzenesulfonate was dissolved together with a suspension stabilizer, and no emulsifier was added after the start of polymerization. The other operations were the same as in the example. The results of the above examples and comparative examples are summarized in Table 1.

[Table] As shown in the examples, it can be seen that the addition of an emulsifier after the start of polymerization significantly improves both the tensile strength and abrasion resistance of the film without increasing the viscosity of the plastisol compared to the comparative example. . Comparison of the drawings (electron micrographs A and B) reveals that this is because the melting state of the blending resin was improved during heating of the plastisol. That is, FIG. 1 shows a film of the resin of Example 1, in which the blending resin particles are completely melted and there is no boundary with the paste resin, whereas FIG. Resin particles remain unmelted.

[Brief explanation of drawings]

The drawings are scanning electron micrographs (300x magnification) of the fractured surface of the film after the tensile test, in which FIG. 1 shows the film from the resin of Example 1 and FIG. 2 shows the film from the resin of Comparative Example 1.

Claims (1)

[Claims] 1. Suspension polymerization of vinyl chloride or a mixture of vinyl chloride and a monomer copolymerizable with vinyl chloride in an aqueous medium containing a polymeric suspension stabilizer using an oil-soluble catalyst, A method for producing a blending resin for polyvinyl chloride paste resin, which comprises adding an emulsifier to the polymerization system or to the obtained polymer after the start of polymerization. . 2 Claim 1 in which the amount of emulsifier added is 0.002 to 5 parts by weight per 100 parts by weight of the total monomer charge
Manufacturing method described in section. 3. The manufacturing method according to claim 1, wherein the emulsifier is added at a polymerization conversion rate of 10% or more. 4. The manufacturing method according to claim 1, wherein an emulsifier is added to the slurry after polymerization. 5. The manufacturing method according to claim 1, wherein the emulsifier is made into an aqueous solution and added to the dehydrated resin. 6. The manufacturing method according to claim 1, wherein the emulsifier is made into an aqueous solution and added to the dry resin.