JPS5964607A - Production of vinyl chloride resin - Google Patents

Abstract

PURPOSE:To obtain porous PVC of a low vinyl chloride monomer content, by using a specified compound in suspension-polymerizing a vinyl chloride monomer in an aqueous medium by using a specified suspending agent. CONSTITUTION:In the production of PVC by polymerizing a vinyl chloride monomer or its mixture with a copolymerizable monomer in an aqueous solvent by using an oil-soluble initiator (A) of the formula (wherein R1 and R2 are alkyl), and a suspending agent comprising partially saponified PVA (average degree of polymerization of 500-2,500, degree of saponification of 65-85mol%, and viscosity in a 4% aqueous solution at 20 deg.C <=50cP) and/or a water-soluble cellulose ester (average degree of polymerization of 70-300 and viscosity in a 2% aqueous solution at 20 deg.C <=500cp); a chlorine-containing ethylenic hydrocarbon as an unsaturated chlorohydrocarbon compound and/or an SH group-, OH group- or COOH group-containing sulfur compound are used together with a nitrogen compound comprising an NH4 group-containing ammonium salt.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for suspension polymerizing vinyl chloride alone or a mixture thereof with other vinyl monomers copolymerizable with it in an aqueous medium. In combination with this, the amount of vinyl chloride monomer (hereinafter abbreviated as VOM) contained in the porous vinyl chloride resin is reduced and stabilizer,
Improved absorption of plasticizer and residual VayO in molded products
The present invention relates to a method for obtaining vinyl chloride resin for the purpose of reducing the amount of vinyl chloride resin.

Recently, there have been reports that VCM can cause liver damage as an effect on the human body, and VCM concentration has decreased in the working environment at vinyl chloride resin manufacturing plants and molding plants, and VCM remains in molded products. A decrease in vCM concentration is sought;
It is considered an urgent sanitary necessity.

Conventionally, vinyl chloride monomers or vinyl chloride monomers and monomer mixtures copolymerizable with them have been mainly produced by suspension polymerization, using organic peroxide-based or azo-based oil-soluble radicals. When carrying out suspension polymerization in an aqueous medium in the presence of an initiator, the suspending agent may be a water-soluble material such as 9-partly saponified polyvinyl alcohol, methyl cellulose, hydroxymethyl cellulose, methyl vinyl ether maleic anhydride copolymer, starch, or gelatin. Polymeric substances are used.

Vinyl chloride monomer and mixture copolymerizable with vinyl chloride monomer 1j Polymerized at 50 to 70°C. After completion of one polymerization, the polymer slurry is heated under reduced pressure with stirring, dehydrated, and dried. We are obtaining vinyl chloride resin products. but.

The residual VOM of polyvinyl chloride resin in the slurry after the unreacted 70M removal step is 10 o o ppm or more1.
Moreover, the product polyvinyl chloride resin after dehydration and drying has residual VCM of 1100 pp or more. This not only worsens the working environment during the polymerization process and molding process, but also causes VOM to remain in the molded product, which is unfavorable from a sanitary standpoint. Vinyl chloride resin or vinyl chloride-based copolymers produced by suspension polymerization are widely used as paste resins for various moldings in the hard and soft fields. It is required to have excellent properties, low fishy eyes, and low residual VCM.

These tendencies lead to a resin with a low degree of polymerization that is easy to process. The degree of polymerization is determined by the polymerization temperature, and as the polymerization temperature increases, the degree of polymerization decreases.

Furthermore, as the polymerization temperature increases, the proportion of non-porous transparent spheres increases.

The amount of residual VCyO depends on the drying conditions of the molded resin and the blending conditions of the composition, but it varies depending on the particle structure of the polymer (9).
affected. In other words, the resin with a microporous particle structure and a lower proportion of transparent spheres is easier to remove residual VCM.

Making the particles porous is an important issue.

An example of a method for solving the above-mentioned problems is as follows.

Tokuko Showa 5, which adopted the method of using sulfur-containing compounds in combination
5-13515. There are methods such as those described in %Kōsho 49-[1746, and various other methods have also been proposed.
Some effects have been recognized. However, these known methods not only have insufficient vCM removal effects (difficult to obtain satisfactory porosity due to drawbacks such as granulation properties during 9-polymerization). .

The present invention solves the above-mentioned drawbacks by suspension polymerizing a vinyl chloride resin or a copolymer resin mainly composed of vinyl chloride, which is porous, has a small amount of residual VOM, less fish eyes, and has excellent thermal stability. The present invention provides a manufacturing method.

Specifically, in the present invention, a specific oil-soluble initiator and suspending agent are used when vinyl chloride or a mixture of vinyl chloride and a monomer copolymerizable with vinyl chloride is suspended.

This production method is characterized by simultaneously using a specific unsaturated chlorinated hydrocarbon compound and/or a specific sulfur-containing compound and a specific nitrogen-containing compound. In this application, a specific nitrogen-containing compound consisting of an ammonium salt having a NH group and a chlorine-containing ethylene hydrocarbon having two carbon atoms and/or a specific sulfur-containing compound having a mercapto group and a hydroxyl group or a carboxyl group are added as a chain transfer agent. It is distinctive in that it is used as a

Among the suspending agents used in the present invention, partially saponified polyvinyl alcohol may be used alone or in combination with a water-soluble cellulose ester.

Partially saponified polyvinyl alcohol has an average degree of polymerization of 500.
~2500. Preferably 600 to 240 [1° degree of saponification 65 to 85 molar, viscosity at 20° C. of a 4 ml aqueous solution measured with a Hepler viscometer is preferably 5 flcp or less, preferably 4
OCT) The following are used.

In addition, the water-soluble cellulose ester used has an average polymerization degree of 7.
0~500. Preferably, 100-250° is measured using an Ubbelohde viscometer at 20°C of a 2% aqueous solution.
o Cp or less, preferably 20 to 400 cp is suitable. The suspending agent is used alone or in combination with partially saponified polyvinyl alcohol or a water-soluble ester, and the total amount used is 0.05 to 0.20 parts by weight, preferably 0.04 to 0.20 parts by weight.
012 parts by weight.

If a suspending agent that deviates from the above-mentioned specified numerical values is used, the powder properties of the produced vinyl chloride resin will be poor and it will often completely solidify in one polymerization tank, which is not preferable.

Also, as an oil-soluble radical initiator, acetylcyclohexane sulfonyl peroxide is used.

Inbutyryl peroxide, 2,2-azobis(4-
methoxy-2,4-dimethyl, valeronitrile), cumyl peroxyneodecanate, diisopropyl peroxydicarbonate, Nuri (4e c-octyl peroxydicarbonate, \-
3-methoxybutyl peroxine carbonate, G2
-Ethylhexyl peroxydicarbonate, di-2ethyneethylperoxydicarbonate, di-methoxyisopropyl peroxydicarbonate, t-butylperoxyneodecanate, t-hexylperoxyneodecanate, 2. Examples include 2'-azobis-(2,4-dimethylvaleronitrile), t-butylbaroxypiparate, t-hexylveroxybiparate, and lauryl peroxide.

In order to achieve the object of the present invention, among the above initiators, the general formula is limited to those represented by 1 R, -0-0-0-R2 (wherein R, , R7 are alkyl groups). They can be used alone or in combination of two or more.

The amount used is 001 to 02 parts by weight, preferably 003 to 010 parts by weight, per 100 parts by weight of vinyl chloride monomer.
Parts by weight. Furthermore, as the unsaturated chlorinated hydrocarbon compound (B) of the chain transfer agent used in combination, a chlorine-containing ethylene hydrocarbon having 2 carbon atoms and/or a sulfur-containing compound having a mercapto group and a hydroxyl group or a carboxyl group (a ) is used together with a nitrogen-containing compound (D) consisting of an ammonium salt having an IJH group, and these compounds are those listed in Table 2.

The amount used is based on the oil-soluble radical initiator.

(A)/(B)/(T)) = 1/1o~20/
0.4~1(A)/(a)/(Di=1/
o1~0510.1~0,5(Al/(c>+
(El)/(D)=1/5~1010.2~07
The weight ratio range is .

If polymerization is carried out outside the range of this ratio condition, the granulation properties will become unstable, coarse particles will be generated at zero, the desired average degree of polymerization will not be obtained, and the porous vinyl chloride resin which is the object of the present invention Otherwise, it is unsuitable because a copolymer resin cannot be obtained with it. It also includes cases where a vinyl monomer copolymerizable with vinyl is contained within 20 parts by weight. Examples of such vinyl monomers include α-olefins such as ethylene and propylene.Me Vinegar! l['-
x Vinyl esters such as vinyl thearate, vinyl ethers such as methyl vinyl ether and cetyl vinyl ether, unsaturated fatty acids including acrylic acid, methacrylic acid and esters thereof, vinyl bromide, vinyl fluoride, etc. Examples include vinyl halides other than vinyl chloride, aromatic vinyl maleic acids such as styrene and α-styrene, fumaric acid and anhydrides, acrylonitrile, and vinylidene chloride.

The present invention specifies a specific saturated chlorinated hydrocarbon (B) and/or a specific sulfur-containing compound (C) as an initiator (A) during suspension polymerization in an aqueous medium using a specific suspending agent. It is characterized in that it is used in combination with the nitrogen-containing compound (D).

Subsequently, the slurry was dehydrated using a centrifugal separation method, and then dried using a hot air drying method to obtain vinyl chloride resin.

Using this, each characteristic value was measured. The results are as shown in Table 5, and all were satisfactory.

Comparative Example 1 (actual@jlF15-6) In Example 1.

Except for the specific nitrogen-containing compound, other similar polymerization and operations were performed to obtain a vinyl chloride resin. The resin thus obtained was as shown in Table 3.

None of them gave satisfactory results.

Comparative Example 2 (Experiment & 7-8) In Example 1.

A vinyl chloride resin was obtained by excluding a specific unsaturated chlorinated hydrocarbon and a specific sulfur-containing compound, setting the polymerization temperature to 67°C, and performing other similar polymerization and operations. The resins thus obtained were as shown in Table 3, but none of them gave satisfactory results.

Comparative Example 3 (Experiments A9-10) In Example 1.

The initiator was changed to di-2-ethylhexyl peroxydicarbonate, and other similar polymerization and operations were performed to obtain a cyclized vinyl resin.

The resins thus obtained were as shown in Table 6, but no satisfactory results were obtained with any of them.

Example 2 (Experiment 11-12), Comparative Example 4 (Experiment 513)
~18) Contents ff2.5? ? SooKg of vinyl chloride monomer, 1000Kg of pure water, initiator and L"i (, 50Kg of t-butyl peroxyvivalate) were placed in a stainless steel polymerization vessel.
0 g, A4 (Table 2) specific sulfur-containing compound 250S'
, A 11 (Table 2) Specific nitrogen-containing compounds 1502
The types of partially saponified polyvinyl alcohol and methylcellulose were changed and the reaction was carried out at a polymerization temperature of 60°C.

The results are as shown in Table 4, saponified tJE of partially saponified polyvinyl alcohol [60-85 mol.

A satisfactory value could not be obtained unless the viscosity of the aqueous solution of methylcellulose at 20°C was 500 cp or less.

Table 4 Comparative Example 5 (Experiment A, 19-22) In a stainless steel polymerization vessel with an internal volume of 25 cm, 500 Kp of vinyl chloride monomer, 1000 Kg of pure water, 300-1000 Kg of t-butyl peroxyvivalate as an initiator, A
5 Partially saponified polyvinyl alcohol 250 (Table 1)
? , A 7 (Table 1) methylcellulose 250v
Under these conditions, a specific unsaturated chlorinated hydrocarbon, a specific sulfur-containing compound, and a specific nitrogen-containing compound were added in the proportions shown in Table 5, and a polymerization reaction was carried out at 60°C.

As shown in Table 5, satisfactory values were not obtained.

Table 5 Example 5 (Experiment A, 25-25) 45 kg of vinyl chloride monomer was placed in a stainless steel polymerization vessel with an internal volume of 25 kg.

50% of monomer such as propylene, ethylene, vinyl acetate, etc. and 1010n0 of pure water. As an initiator, t-butylbaroxypivale = +500f, Table 2.Specific sulfur-containing compound of 4゜4 250y, Table 2. Specific nitrogen-containing compounds 15
Prepare 02.

The reaction was carried out at a polymerization temperature of 60°C, and the same procedure as in Example 1 was followed thereafter. As shown in Table 6, the polymerization results were satisfactory in all cases.
Polymerization was carried out using the polymerization conditions of Example 6 except for the specific nitrogen-containing compound shown in Table 2.

As shown in Table 6, the results were not satisfactory in any case.

Claims (1)

[Scope of Claims] 1) Vinyl chloride monomer alone or a mixture of vinyl chloride monomer and a monomer copolymerizable with it is prepared in an aqueous medium with the general formula R, -C-0-0-R2 (in the formula An oil-soluble radical initiator (R, , R2 represents an alkyl group)
A) as a suspending agent, average degree of polymerization: 500 to 250
0. Saponification degree 65-85 morti. Partially saponified polyvinyl alcohol whose viscosity at 20°C of the 4th aqueous solution is 50 cp or less/or an average degree of polymerization of 70 to 500, and the viscosity of the 2nd aqueous solution at 20°C of 50 cp or less
A water-soluble cellulose ester having a molecular weight of 0 cp or less is used, and at that time, a chlorine-containing ethylene hydrocarbon having 2 carbon atoms and/or a tahamerkabuto group and a hydroxyl group or a carboxyl group are used as the unsaturated chlorinated hydrocarbon compound (B). A method for producing a vinyl chloride resin, characterized in that a nitrogen-containing compound (D) consisting of an ammonium salt having an NH4 group is used in combination with the sulfur-containing compound (C). 2) The amount of oil-soluble radical initiator (A) used is 0.03 to 0.10 parts by weight based on the vinyl chloride single cap, unsaturated chlorinated hydrocarbon compound (B), sulfur-containing compound (0) and/or Or the amount of the nitrogen-containing compound (D) is the oil-soluble radical initiator (
For A). (A)/(B)/(D)=1/1o~2o/u, a
~1(A)/(c)/(D) = 1/o, 1
~0.510.1~05(A)/(B)+(0)
The method for producing a vinyl chloride resin according to claim 1, wherein the vinyl chloride resin is used in a weight ratio range of / (1)) = 1/5 to 1010.2 to 0.07.