JPS6026402B2 - Suspension polymerization method of vinyl monomers - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for suspension polymerization of vinyl monomers that has excellent polymerization stability and very little adhesion of the polymer to the inner wall of a polymerization tank.

Suspension polymerization dispersants used in the suspension polymerization method of vinyl monomers include water-soluble polymeric substances and water scale-soluble inorganic or organic metal salts.

As elutriation-soluble inorganic salts, clay pigments such as kaolin and talc, calcium phosphate, calcium carbonate, and the like have been known for a long time. Since the COD burden on wastewater is small and tertiary treatment is easy, it has recently been frequently implemented industrially. As water-soluble inorganic salts, phosphate metal salts (especially calcium salts are used) are widely used and are typical inorganic dispersants.

The suspension polymerization method using metal phosphate salts has extremely poor reproducibility and requires a large amount of dispersant to obtain a stable suspension system (a large amount of dispersant will inevitably affect the product polymer). It has drawbacks such as an extremely narrow range of operation and a very narrow range of operation. In addition, in the suspension polymerization method of vinyl monomers, which uses dispersants regardless of whether they are inorganic or polymeric, the polymer adheres to the inner wall of the polymerization tank, and polymerization cannot be completed without removing the adhered substances. If the process continues, the deposits will grow, causing various adverse effects such as a decrease in the cooling rate due to a decrease in the heat transfer coefficient, and a decrease in the quality of the product polymer. Therefore, in reality, it is necessary to remove these deposits, resulting in a significant drop in productivity, and since it is impossible to completely remove them, this poses serious problems such as a decline in product quality. There is. In order to solve these drawbacks, the combined use of various surfactants and water-soluble inorganic salts has been proposed, but this is still far from satisfactory.

The present invention completely overcomes the above-mentioned drawbacks as a result of intensive studies on suspension polymerization formulations of vinyl monomers with excellent polymerization stability using water-soluble metal phosphates as dispersants. The present invention was completed by discovering a suspension polymerization method that has excellent polymerization stability and reproducibility over a wide range of conditions and that causes very little polymer adhesion to the inner wall of the polymerization tank.

That is, the present invention involves suspending at least one polymerizable vinyl monomer and a mixture of the monomer and a polymeric substance that is soluble in a single star, with an inorganic compound totally soluble in water. When performing aqueous suspension polymerization as a dispersant, the general formula (in the formula,
R is an alkyl or aralkyl group having 8 to 30 carbon atoms, A is day, Na or K, n is 5 to 50, m is an integer of 1 to 3), This is a suspension polymerization method of vinyl monomers dissolved in 0.0001 to 0.5% by weight of the monomer.

When the above-mentioned surfactant (1) used in combination is dissolved in the monomer, better results are obtained than in the aqueous phase in terms of polymerization stability, polymer adhesion to the pot, etc.

The vinyl monomer used in the present invention may be of any type as long as it has a vinyl group. In this case, homopolymerization of one type of monomer, copolymerization of two or more types of monomers, graft polymerization in the coexistence of natural rubber or synthetic rubber, etc. can be carried out without any problem. Examples of these vinyl monomers include styrene, acrylonitrile, methyl acrylate, and methyl methacrylate. As the dispersant, any phosphate salt that is sparingly soluble in water can be used. Examples include calcium hydrogen phosphate, calcium phosphate, magnesium hydrogen phosphate, magnesium phosphate, and similar iron salts, aluminum salts, zinc salts, and the like. Surfactant used in the present invention (1
) are shown in Table 1.

(The above R, n, and m may be a mixture of multiple types)
In addition to the above-mentioned surfactant (1), other types of surfactants can also be used in combination.

As the initiator, a transparent radical initiator, that is, a peroxide type, hydroperoxide type, or azobis type initiator, is used.

Examples include lauroyl peroxide, benzoyl peroxide, tertiary butyl hydroperoxide, and azobisisobutyronitrile. These can be used alone or in combination. Furthermore, chain transfer agents, plasticizers, discoloration inhibitors, etc. can also be used in combination.

When the suspension polymerization method of the present invention is used, polymerization stability and reproducibility are excellent, and adhesion of the polymer to the inner wall of the polymerization tank is extremely small, resulting in marked improvement in productivity and operability.

This will be explained below using examples. Example 1 Using the reaction vessel (Material: SUB-32), 3 parts of acrylonitrile (same parts by weight and below) and 70 parts of styrene were thoroughly mixed, and 0. 0.003 parts, azobisisobutyronitrile 0.2 parts, and tertiary dodecyl mercaptan 0.4 parts are dissolved.

After thoroughly dispersing 1.0 part of calcium phosphate in 10 parts of water, add the above monomer solution and heat at 80°C while keeping the light on.
Polymerizes over time. Thereafter, the mixture was reacted for 1 hour at 10 mm, cooled, and the polymer beads were taken out. Dilute hydrochloric acid was added to dissolve and remove the dispersant, followed by dehydration, washing, and drying to obtain bead-shaped polymers. A spherical polymer with good suspension stability and uniform particle size was obtained. In addition, on the inner wall of the polymerization vessel, only a small amount of polymer was observed near the liquid surface, and almost no polymer was observed on other parts. Comparative Example 1 Suspension polymerization was carried out using the same charging composition and the same polymerization procedure as in Example 1, except that Gafac GB520 was not used.

The polymerization system became unstable and coalesced midway. Comparative example 2 0 sodium lauryl sulfate instead of GafacGB520
．． Example 1 except that 0.003 parts was used after being dissolved in the aqueous phase.
I did the same thing.

Although the polymer was obtained in piece form, the beads were agglomerated because the polymerization system was unstable. Moreover, the furnace solution after polymerization was cloudy and an emulsion polymer was produced. The polymer was thickly adhered to the entire inner wall of the polymerization pot. Comparative Example 3 The same procedure as Example 1 was carried out except that 0.003 part of dioctyl sulfosuccinate was used instead of GafacGB520.

Since the polymerization system was unstable, the beads obtained were agglomerated. Further, the polymer was thickly adhered to the entire inner wall of the polymerization pot. Comparative Example 4 The same procedure as in Example 1 was carried out, except that 0.003 part of sodium laurylbenzenesulfonate was dissolved in the aqueous phase instead of OafacGB520.

Spherical beads were obtained, but the furnace solution became slightly cloudy and an emulsion polymer was produced. Further, the polymer was adhered to the entire inner wall of the polymerization vessel in a streamlined manner. Example 2 The same operation as in Example 1 was performed except that 0.003 part of OafacPE960 was dissolved in the monomer temperature mixture and used instead of GafacGB520.

A normal spherical polymer was obtained, and no emulsion polymer was formed. In addition, there was very little polymer adhesion to the inner wall of the polymerization tank, which was only near the liquid surface. Example 3 The same procedure as in Example 1 was carried out, except that 0.003 part of OafacRS710 was dissolved in the single body mixture and used instead of GafacGB520.

A normal polymer was obtained, and the amount of polymer adhering to the inner wall of the polymer was very small, with only a small amount adhering near the liquid surface. Comparative Example 5 Polymerization was carried out in the same manner as in Example 1, except that 0.05 part of polyvinyl alcohol (average degree of polymerization 170u, degree of saponification 80%) was used instead of 1 part of calcium phosphate.

A normal polymer was obtained, and the furnace solution after polymerization was also transparent and no emulsion polymer was observed. However, the polymer was adhered to the entire wall of the polymerization plant. Comparative example 6 Calcium phosphate 1. Polymerization was carried out in the same manner as in Example 1, except that 0.2 g of carboxydimethyl cellulose was used instead of the polymer.

A normal polymer was obtained, and the furnace solution after polymerization was also clear and no emulsion polymer was observed. However, a film of polymer was adhered to the entire inner wall of the polymerization tank. Comparative Example 7 Same formulation as Example 1 except that 0.005 part of Emulgen 420 (manufactured by Kao Soap Co., Ltd., polyoxyethylene oleyl ether, HLB=136) was used instead of GafacGB5200.00 Moribe. Polymerized with

Claims (1)

[Claims] 1. At least one polymerizable vinyl monomer, or a mixture of the monomer and a polymer substance soluble in the monomer, is an inorganic compound that is sparingly soluble in water. When performing aqueous suspension polymerization as a suspension dispersant, there are general formulas ▲ mathematical formulas, chemical formulas, tables, etc. 0.0001 to 0.5% by weight of a phosphate ester type nonionic surfactant (n is 5 to 50, m is an integer of 1 to 3) based on the monomer.
Suspension polymerization of vinyl monomers used by dissolving them in monomers.