JPS60235807A - Production of vinyl chloride polymer - Google Patents

Abstract

PURPOSE:To produce a blending resin for PVC paste resins, comprising low- porosity single particles having a dense surface, by suspension-polymerizing a vinyl chloride monomer in the presence of a specified PVA and a hydrophilic nonionic surfactant as a suspension stabilizer. CONSTITUTION:In the suspension polymerization of vinyl chloride in the presence of a catalyst soluble in vinyl chloride monomer and a suspension stabilizer and, optionally, a pH-buffering agent; said suspension stabilizer comprises (A) PVA having an average degree of polymerization of 1000-2500, a degree of saponification of 60-85mol%, and a m.p. <= the polymerization temperature and (B) a hydrophilic nonionic surfactant (e.g., polyoxyethylene lauryl ether). It is suitable to use 0.1-2.0wt%, based on the monomer, component A and 0.1- 1.0wt%, based on the monomer, component B. Thus, a blending resin for PVC paste resins, which is used in conjunction with a PVC paste resin, and shows good flow when it is made into a plastisol (together with a plasticizer) and is excellent in the quality of a molding formed by heating this sol.

Description

Detailed Description of the Invention The present invention provides a polyvinyl chloride paste resin which has good fluidity when used together with a polyvinyl chloride paste resin and is made into a plastisol with a plasticizer, and which has excellent quality in the molded product obtained by heat molding this sol. The present invention relates to a method for producing a blending resin for vinyl paste resin.

PVC paste resin contains plasticizer, secondary plasticizer,
It is stirred and kneaded with diluents, stabilizers, low fillers, etc. to form a sol, and used in various finished products by methods such as coating, dipping, casting, and spraying. Therefore, fluidity is suitable for each molding method from the viewpoint of processability.

A sol with viscosity is required. In particular, in sol molding under high shear such as coating methods, a blending resin for paste resin is often used to reduce the viscosity of the sol.

In addition, for the purpose of matting the surface of a molded product, it is preferable to use single particles having an average grain size of 20 to 80 microns, low porosity, and a dense and smooth surface.

During this manufacture, special materials must be present in the polymerization system in order to obtain dense, spherical beads of polymer or copolymer with the desired particle size and distribution. The first important material is a suspending or dispersing agent with an average degree of polymerization of 1000-2500. Saponification degree 60-85
It is polyvinyl alcohol with a mole content of 1% and a cloud point below the polymerization temperature.

The suspending agents described above are only applicable to the present method in combination with nonionic surfactants as described below.

The suspending agent or dispersing agent is used in an amount in the range of about 11 to 2-0% by weight, preferably in the range of about α5 to 1.5%, based on the total amount of monomers charged. be done. The dispersant is
It can be added to the reaction system at any time before the start of the reaction. However, it is usually added to the reaction system as an aqueous solution prior to the addition of the monomers.

One of the most important aspects of this invention is the use of certain suitable surfactants in the polymerization of monomers. The surfactant used together with the above-mentioned polyvinyl alcohol is nonionic and hydrophilic, and has an HLB of 15 or more. Preferably, the surfactant has an HLE of 17 or more. The higher the HLB of the surfactant, the better, ie, the more easily the surfactant dissolves in water, the more desirable properties will be obtained.

The effectiveness of nonionic surfactants is related to the polarity of the molecule, ie the relationship between polar hydrophilic groups and nonpolar hydrophobic groups. The polarity of this nonionic surfactant is determined by the empirical numerical value called HLB, as described above.

The amount of surfactant used in the present invention ranges from about α05 to 1.0% by weight based on the total monomer charge.

If the measure is less than α05%, its effect will not be sufficient, and 1
．． If it is more than 0%, the sol viscosity lowering effect may be adversely affected. More than one surfactant can be used in combination as long as the combined HLB is not less than 15.

The surfactants used here have the effect of working with the aforementioned polyvinyl alcohol to form smaller, spherical particles with a narrow particle size distribution.

As mentioned above, nonionic surfactants with appropriate HLB include fatty acid esters of polyoxyethylene and aromatic esters of polyoxyethylene.

It is included in the categories of aliphatic and aromatic ethers of polyoxyethylene, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, block copolymers of polyoxyethylene and polyoxypropylene, and the like. Suitable surfactants include polyoxyethylene lauryl ether, oleyl ether.

Examples include octylphenyl ether, /nylphenyl ether, polyoxyethylene monostearate, palmitate, and oleate.

Surfactants can be added to the reaction system at any time prior to polymerization.

However, it is usually added before the addition of the monomers, and its form can either remain solid or be an aqueous solution.

The catalyst or initiator used in the present invention is soluble in the monomer. For example, azobisisobutyronitrile
Z 2/-azobis(2,4-dimethylvaleronitrile), tert-butylperoxybipacite, benzoyl peroxide, dioctylcyclohexylsulfonyl peroxide.

Oil-soluble catalysts or free radical initiators with low aqueous solution such as tert-butyl peroxyneodecanate, acetylcyclohexylsulfonyl peroxide. The catalyst or initiator selected in the present invention is used in an amount ranging from about α01 to α5% by weight, based on the total monomer charge. Catalysts or initiators can be added to the reaction system at any time as long as the reaction system is maintained below the decomposition temperature of the particular catalyst. However, in the present invention, the catalyst or initiator is added as the last added component before raising the reaction system to a predetermined temperature. The temperature of the reaction in the present invention is typically in the range of 50 to 70°C. Particularly satisfactory results are obtained when the reaction temperature is in the range 50-60°C.

The reaction time is usually 6 to 12 hours, and the reaction system is stirred throughout the reaction time. Agitation is usually constant during the reaction cycle, but may be varied if necessary. It is clear that the combination of polyvinyl alcohol with a cloud point below the polymerization temperature and a hydrophilic surfactant used in the present invention produces particles of vinyl chloride resin that are spherical and have no porosity. Since the polyvinyl alcohol used in the present invention precipitates in the polymerization system at the polymerization temperature and exists as fine particles, it seems to act independently of the hydrophilic surfactant. Hydrophilic surfactants are
Stirring determines the size of the monomer droplets and the size of the vinyl chloride resin produced, which contributes to reducing the porosity of the particles. If the HLB of the surfactant is less than 15, a portion of the surfactant will dissolve in the monomer layer and proceed to the polymer/monomer interface inside the polymer during the polymer formation process, resulting in -
It prevents the fusion of secondary particles and gives porosity.

In general, polyvinyl alcohol becomes precipitated fine particles at the polymerization temperature, and has the same effect as an inorganic dispersant to prevent coalescence and aggregation of dispersed vinyl chloride resin particles due to mutual stirring shear.

When the degree of saponification of polyvinyl alcohol exceeds 85 mo1%, the cloud point exceeds the polymerization temperature and exists as an aqueous solution during the reaction. Therefore, they exist in the same region as the hydrophilic surfactant, canceling out their individual effects and destabilizing the inside of the polymerized thread.

The present invention will be explained below using Examples, but the contents of the Examples are not intended to limit the scope of the present invention.

Example 1 Pure water was poured into an autoclave equipped with stirring blades at 30°C and 9°C. Average degree of polymerization: 2000. Saponification degree 75
Polyvinyl alcohol 100 with mo1% and cloud point of 40℃
An aqueous solution of 9 dissolved in 5 pure water, 109. in polyoxyethylene lauryl ether/. α, α/-Azobisu2.
After adding 10 g of 4-dimethylvaleronitrile, the autoclave was sealed and oxygen from the polymerization system was evacuated. After adding vinyl chloride monomer 9:20 to this, stirring was started, the temperature was raised to 65° C., and the polymerization reaction was started. Polymerization was stopped when the autoclave internal pressure decreased to 7.5 IC9/d.

The polymer slurry was removed from the reactor, washed with water and dried in the usual manner.

Examples 2 to 5 Polymers were obtained in the same manner as in Example 1, except that the surfactants shown in Table 1 were used in place of polyoxyethylene lauryl ether.

Comparative Example 1 A polymer was produced by polymerization in the same manner as in Example, but no emulsifier was added.

Comparative Example 2 A polymer was obtained in the same manner as in Example 1, except that polyoxyethylene nonylphenyl ether was used instead of polyoxyethylene lauryl ether.

The physical property values shown in Table 1 were evaluated by the following method.

1) Average particle size Measured by Coulter counter in water.

Regarding operation and equipment, by T. A11on @par
"Ticle 5ize Measurement" 1st
Chapter 3, 2nd edition (1975), Ghapman and
Published by Hall, London;

2) Intraparticle porosity 31 The particles are dispersed in n-butyl alcohol, and immediately after that, the sample is exposed to transmitted light and observed with an optical microscope. Particles with internal pores reflect transmitted light diffusely and are observed as black particles.

The number of pores was determined based on the ratio of the number of black particles to the total number of particles.

6) Sol viscosity blender resin 31. After adding Dioctyl 7 Talate 509 as a plasticizer to Base Resin 709, the mixture was stirred and dispersed using a mixer and defoamed to prepare plastisol.

The paste resin has a sol viscosity of 9660 cps consisting of 100 parts by weight of the paste resin and 50 parts by weight of dioctyl phthalate.
I used the one from The measurement was carried out using a Brookfield viscometer at a constant temperature of 23° C. on a spindle rotating 20 times per minute.

Claims (4)

[Claims] (1) A suspension stabilizer in a process for producing polymers and copolymers of vinyl chloride by suspension polymerization in the presence of a vinyl chloride monomer soluble catalyst and one or more suspension stabilizers, optionally a pH-al buffer. As, the average degree of polymerization is 1000-2500. Saponification degree 60-85mol
%, the 4j point is below the polymerization temperature, and a hydrophilic anionic surfactant is used. (2) The method according to claim (1), wherein the amount of polyvinyl alcohol added is α1 to 2.0% by weight of the monomers used. (3) The method according to claim (1), wherein the amount of nonionic surfactant added is Q,01 to 1.0% by weight of the monomers used. (4) The method according to claim (1), wherein the nonionic surfactant has an HLB of 15 or more.