KR19990010949A - Production method of vinyl chloride resin for paste processing excellent in heat discoloration property - Google Patents

Abstract

The alkali metal salt of alkyl sulfates or alkyl benzene sulfonates having 10 to 30 carbon atoms is added to the reactor in an amount of 0.5 to 2.0 parts by weight based on 100 parts by weight of a monomer mixture copolymerizable with vinyl chloride to copolymerize with an organic peroxide, a vinyl chloride monomer and a vinyl chloride monomer The amount of the vinyl chloride monomer and the comonomer mixture introduced into the reactor was increased to 0.5 parts by weight based on 100 parts by weight of the total amount of the vinyl chloride monomer and the comonomer mixture introduced into the reactor for the purpose of improving heat discoloration of the vinyl chloride resin for paste processing after injecting the comonomer or vinyl chloride based latex. To 10 parts by weight were charged into a reactor, and the mixture was heated to a predetermined polymerization temperature through a usual homogenization process. The resultant latex was subjected to ordinary spray drying to remove water to prepare a vinyl chloride resin for pure paste processing do.

Description

Production method of vinyl chloride resin for paste processing excellent in heat discoloration property

Vinyl chloride resin for paste processing is a general purpose resin which is widely used for everyday household goods and industrial use such as architectural flooring, wallpaper, artificial leather product, woven cloth, sheet, packaging and agricultural film. The paste vinyl chloride resin is usually mixed with a plasticizer to prepare a paste sol, and then the product is processed through a processing process in a temperature range significantly higher than the deterioration temperature of the resin. Due to the high processing temperature condition of the vinyl chloride resin for paste processing or the deterioration due to heat, light, moisture or the like depending on the environment in which the synthetic resin is used, hydrogen chloride in the resin component is released and an unsaturated bond structure is formed in the chain, There is a problem that a discoloration phenomenon occurs. Such a discoloration phenomenon is referred to as a heat discoloration phenomenon.

When the vinyl chloride resin is decomposed by heat, hydrogen chloride is generated, and the generated hydrogen chloride acts as a catalyst for promoting decomposition of the resin.

In order to solve these problems occurring during processing, a lot of efforts have been made. By dividing the structure and properties of the resin itself during the process of producing vinyl chloride resin for paste processing, the heat discoloration phenomenon And a method of using a stabilizer for suppressing the discoloration problem in the molding process.

A method of using a stabilizer in the molding process to suppress heat discoloration of a vinyl chloride resin is more preferable than a method of suppressing a heat discoloration phenomenon by changing the structure and properties of the resin in the vinyl chloride resin production step for paste processing Although the chemical composition of the stabilizer used in the process of forming is mainly composed of an organometallic compound, the use of the organometallic compound is often limited in relation to environmental problems, It can not be a preferable solution of the above. In addition, when a stabilizer is used in the process of molding to suppress the discoloration of the vinyl chloride resin for paste processing, there is an effect in a certain processing temperature range. However, when the stabilizer is not used at the heating temperature There may be a case where the phenomenon of discoloration of the heating proceeds more rapidly.

In order to suppress the discoloration of the vinyl chloride resin for paste processing due to various technical problems as described above, a method of improving the stability against heat discoloration of the vinyl chloride resin itself for paste processing and a suitable stabilizer There are many cases where two methods are used together.

The present invention relates to a method for suppressing discoloration of heat of a vinyl chloride resin itself in a step of manufacturing a vinyl chloride resin for paste processing, in order to solve the problem of heat discoloration occurring during processing of a vinyl chloride resin for paste processing.

US Pat. No. 5,319,028, assigned to Nippon Zeon Co., Ltd., as a prior art for suppressing the discoloration of the vinyl chloride resin itself for paste processing, discloses that methyl vinyl chloride resin for paste processing Discloses a method of improving the processing temperature and thermal stability of a product during paste processing by copolymerizing methyl methacrylate on the surface of a vinyl chloride resin latex by adding a methacrylate monomer, When suspension polymerization is carried out, polymethylmethacrylate on a bead or pellet having a molecular weight of 10,000 to 5,000,000 is homogenized together with vinyl chloride, water, a polymerization initiator and an emulsifier, thereby producing a vinyl chloride resin for paste processing excellent in viscosity stability And the like.

In the prior art for improving heat discoloration of a vinyl chloride resin for paste processing, methyl methacrylate is added to the late stage of the polymerization reaction in the production of a vinyl chloride resin for paste processing, and methyl methacrylate However, this method has a difficulty in the production process in which methyl methacrylate must be added to overcome the high reaction pressure of vinyl chloride. In addition, Japanese Patent Application Laid-Open (Kokai) discloses a polyurethane foam in the form of a bead or a pellet during the production of a vinyl chloride resin for paste processing, The present invention aims at improving the viscosity stability of a vinyl chloride resin for paste processing and thus has not satisfactorily solved the problems of the prior art.

The present invention relates to a process for producing a vinyl chloride resin for paste processing having an excellent heat discoloration inhibiting effect and a process for producing a vinyl chloride resin for paste processing by adding polymethyl methacrylate to the homogenization process during the production of the resin, And the effect is improved, leading to the present invention.

The contents of the present invention will be described in detail as follows.

First, 0.5 to 2.0 parts by weight of an alkali metal salt of an alkylsulfate or an alkylbenzenesulfonate having 10 to 30 carbon atoms is added to a reactor to 100 parts by weight of a monomer mixture copolymerizable with vinyl chloride to copolymerize with an organic peroxide, a vinyl chloride monomer and a vinyl chloride monomer After injection of a possible comonomer or vinyl chloride based core latex, polymethyl methacrylate is added to 100 parts by weight of the total amount of vinyl chloride monomer and comonomer mixture for the purpose of improving heat discoloration of the vinyl chloride resin for paste processing 0.5 part by weight to 10 parts by weight based on 100 parts by weight of the total amount of the latex, and the mixture is heated to a predetermined polymerization reaction temperature through a usual homogenization process and reacted. Then, the obtained latex is subjected to ordinary spray drying to remove water, .

In the present invention, a vinyl chloride resin is a resin polymer having a composition of 70% or more by weight of a vinyl chloride monomer in the resin composition as a whole, means a resin composed solely of a vinyl chloride monomer or a copolymer copolymerized with a monomer copolymerizable with a vinyl chloride monomer do. Monomers copolymerizable with the vinyl chloride monomer include vinyl acetate, acrylates, methacrylates, olefins of ethylene and propylene, and unsaturated fatty acids such as acrylic acid, methacrylic acid, itaconic acid and maleic acid, and anhydrides of these fatty acids And are widely used in conventional methods of copolymerizing vinyl chloride in general.

The amount of the alkylsulfate or alkylbenzenesulfonate alkali metal salt having 10 to 30 carbon atoms used as an emulsifier in the present invention is preferably 0.5 to 2.0 parts by weight based on the total amount of the monomers to be added and preferably about 1.0 part by weight or more, good. When the amount of the emulsifier is less than the above range, it is difficult to maintain the stability of the latex. When the amount of the emulsifier is excessively used, the recovery process of the residual emulsifier after polymerization is excessively delayed to lower the production efficiency.

In the present invention, the composition and amount of methyl polymethacrylate used for suppressing heat discoloration of the vinyl chloride resin for paste processing are as follows. The composition of the polymethyl methacrylate used in the present invention may be either a pure methyl methacrylate polymer or a methyl methacrylate copolymer. Examples of the monomers copolymerizable with methyl polymethacrylate effective for suppressing heat discoloration of the paste vinyl chloride resin include a copolymer having a unsaturated double bond, a copolymer having an epoxy group, a copolymer having a carboxyl group Retention, and steric retention with a hydroxyl group.

First, examples of the unsaturated double bond-containing copolymer having a unsaturated double bond include ethyl acrylate, ethyl methacrylate, n-propyl acrylate, n-propyl methacrylate, iso-propyl acrylate, iso-propyl methacrylate, Acrylate, isobutyl acrylate, iso-butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, lauryl acrylate, lauryl methacrylate, Stearyl acrylate, stearyl methacrylate, alpha methyl styrene, and the like;

Examples of a steric residue containing an epoxide group include glycidyl acrylate and glycidyl methacrylate;

Also, the copolymer residue containing a carboxyl group includes acrylic acid, methacrylic acid, itaconic acid, fumaric acid, and maleic acid;

Examples of the copolymer having a hydroxyl group include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl acrylate , And 2-hydroxybutyl methacrylate.

The comonomer exemplified above can be used in an amount of 1 to 50 parts by weight based on the whole composition of methyl methacrylate.

To suppress heat discoloration of the vinyl chloride resin for paste processing, the amount of the methyl methacrylate polymer having the composition within the above range used in the present invention is preferably 0.5 to 10 parts by weight based on 100 parts by weight of the total charged monomers. In addition, the charging method may be carried out batchwise at the initial stage of the polymerization reaction or continuously with the progress of the polymerization reaction, but a method of batch addition at the beginning of the reaction is more preferable.

Catalysts which can be used in the micro suspension polymerization or in the core microsuspension polymerization of the present invention include organic peroxides. As a concrete example of organic peroxide catalysts

Diacyl peroxides such as dipentylperoxide, di-3, 5, 5-trimethylhexanoyl peroxide, and diaryl peroxide;

Peroxydicarbonates such as diisopropyl peroxydicarbonate, di-2-ethyl peroxydicarbonate, and di-2-ethylhexyl peroxydicarbonate;

Peroxyesters such as tertiary butyl peroxypivalate and tertiary butyl peroxy neodecanoate;

Azo compounds such as azobisisobutyronitrile, azobis 2-methylbutyronitrile and azobis-2, 4-dimethylvaleronitrile;

And sulfates such as potassium persulfate and ammonium persulfate.

These organic peroxides can be used singly or in combination of two or more kinds.

The amount of the initiator used is determined by factors such as the manufacturing process, productivity, quality, etc. Generally, 0.5 to 2.0 parts by weight of an initiator may be used per 100 parts by weight of the total charged monomers, and most preferably 0.8 to 1.5 parts by weight . When the initiator is used in an excessively small amount, the reaction time is delayed to deteriorate the productivity. When the amount of the initiator is excessively used, the initiator is not completely consumed during the polymerization and remains in the final resin product, thereby deteriorating the thermal stability and color quality of the resin.

The additives described above are added to a homogenization reactor together with deionized water, homogenized, and then transferred to a polymerization reactor for micro suspension polymerization or cardiac microsuspension polymerization.

In general, the degree of polymerization of vinyl chloride resin is determined by the polymerization reaction temperature. Since the degree of polymerization of the resin greatly affects the processing conditions and physical properties of the product, a suitable reaction temperature should be selected. The general polymerization temperature of the vinyl chloride resin produced for commercial purposes is 30 to 80 캜. The latex obtained after completion of the polymerization reaction is dried and pulverized according to a conventional method to finally produce a paste-form vinyl chloride resin in powder form.

A paste was prepared from the final vinyl chloride resin obtained by the above method to prepare a sheet. The sheet was allowed to stand at 200 占 폚 for 3 minutes, and the degree of discoloration of heat was measured with a colorimeter. As a result, the vinyl chloride resin prepared by the method of the present invention It was confirmed that the effect of suppressing heat discoloration was improved.

The following examples and comparative examples are given to illustrate the present invention in detail but the present invention is not limited to these examples.

Example 1

3 kg of lauryl sulfate sodium salt, 1.5 kg of a straight chain aliphatic higher alcohol having 12 to 16 carbon atoms, 300 gr of 2-ethylhexyl peroxydicarbonate, 120 gr of dilauryl peroxide, 3 kg of polymethyl acrylate and 400 l of deionized water were charged into the reactor After vacuuming, 400 l of vinyl chloride and 3 kg of polymethyl acrylate were added and homogenized. The reaction temperature was raised to 50 ° C to perform micro suspension polymerization. The latex thus obtained is spray-dried by a conventional method to obtain a powdery paste-form vinyl chloride resin.

Example 2

70 kg of vinyl chloride latex having a solid content ratio of 45% and different particle diameters, 1 kg of sodium dodecylbenzenesulfonate, 3 kg of polymethyl methacrylate and 400 L of deionized water were charged into a reactor, 400 L of vinyl monomer is added, homogenized, and then the reaction temperature is raised to 50 캜 to perform the core microsuspension polymerization. The latex thus obtained is spray-dried by a conventional method to obtain a vinyl chloride resin.

Example 3

3 kg of sodium lauryl sulfate, 1.5 kg of linear aliphatic higher alcohols having 12 to 16 carbon atoms, 300 gr of 2-ethylhexyl peroxydicarbonate, 120 gr of perryour peroxide, 3 kg of polymethyl acrylate and 400 l of deionized water were fed into the reactor And 3 kg of a copolymer resin having a weight ratio of methyl methacrylate and glycidyl methacrylate of 90:10 was introduced into 400 l of a vinyl chloride monomer and homogenized. The reaction temperature was raised to 50 ° C to prepare a micro suspension polymerization . The latex thus obtained is spray-dried by a conventional method to obtain a powdery paste-form vinyl chloride resin.

Example 4

70 kg of vinyl chloride latex having a solid content ratio of 45% and different particle sizes, 2 kg of core type vinyl chloride latex, 1 kg of sodium dodecylbenzenesulfonate, a weight ratio of methyl acrylate and glycidyl methacrylate of 90:10 3 kg of copolymer resin and 400 L of deionized water were charged into the reactor and vacuumed. Then, 400 L of vinyl chloride monomer was added thereto, and homogenized. The reaction temperature was raised to 50 ° C. to perform the microsuspension suspension polymerization. The latex thus obtained is spray-dried by a conventional method to obtain a vinyl chloride resin.

Comparative Example 1

In Example 1, the vinyl chloride resin was obtained in the same manner as in Example 1 except that polymethylmethacrylate was not added during the polymerization of the vinyl chloride resin.

Comparative Example 2

In Example 2, the vinyl chloride resin was obtained in the same manner as in Example 2 except that polymethylmethacrylate was not added during the polymerization of the vinyl chloride resin.

Evaluation of heat discoloration

(1) Evaluation sample preparation

1. Manufacture of paste sol

100 parts of dioctyl phthalate 60

And 1 part by weight of a heat stabilizer were added, and the paste sol was mixed with a high-

After manufacturing, air bubbles in the paste sol are removed.

2. Sheet manufacture

The paste sol prepared by the method of 1 was coated to a thickness of 0.54 mm,

.

(2) Measurement of heat discoloration property

The prepared sheet was allowed to stand at a high temperature of 200 DEG C for 3 minutes, and then the yellowness degree was measured using a colorimeter to measure the yellowness degree.

Results of measurement of discoloration of heat

Physical property measurement item Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Heat discoloration [Yellowness] 3.3 3.8 4.5 5.1 6.8 7.2 Transparency [%] 86.7 92.3 85.8 91.4 86.1 90.2 Polymerization reaction time [hour] 9.5 9.5 9.0 9.0 10.0 10.3 Solid content ratio of the final latex [%] 49.2 49.5 50.4 50.7 48.0 48.3

Claims (9)

Characterized in that 0.5 to 10 parts by weight of polymethyl methacrylate is added to 100 parts by weight of the monomer at the initial stage of the polymerization in the micro suspension polymerization of the vinyl chloride monomer, Gt; The method according to claim 1, wherein the co-monomer copolymerizable with the vinyl chloride monomer is subjected to a fine suspension polymerization reaction together with the vinyl chloride monomer. The method according to claim 1 or 2, wherein the vinyl chloride monomer is polymerized by a micro suspension polymerization method. The method according to claim 1 or 2, wherein the vinyl chloride monomer is polymerized by a core seed fine suspension polymerization method. The method according to claim 1, wherein the methyl methacrylate polymer is copolymerized with a comonomer selected from the group consisting of a comonomer having an unsaturated double bond, a comonomer having an epoxy group, a comonomer having a carboxyl group and a comonomer containing a hydroxyl group Chain method. 6. The method of claim 5 wherein the comonomer composition is from 1 to 50 weight percent of the total composition of the methyl methacrylate polymer. The method according to claim 5 or 6, wherein the composition ratio of the comonomer is 10% by weight or less. The method according to claim 5 or 6, wherein the comonomer is a comonomer having an epoxy group. The method according to claim 8, wherein the monomer having an epoxy group is selected from glycidyl acrylate and glycidyl methacrylate.