KR100398738B1 - Process for the Production of the Partial Highly Heat Stable Vinyl Chloride Polymer - Google Patents

Abstract

PURPOSE: A method for preparing a vinyl chloride-based resin for straight processing prepared by suspension polymerization of a vinyl chloride monomer is provided, to improve thermal stability and to reduce the discoloration due to heating. CONSTITUTION: The method comprises the step of adding 0.3-10 parts by weight of a methyl methacrylate resin with a molecular weight of 20,000-100,000 at a time to 100 parts by weight of a monomer in the initial step of polymerization. Preferably the vinyl chloride monomer is suspension polymerized with a co-monomer, and the co-monomer is vinyl acetate, acrylates, methacrylates, an unsaturated fatty acid or a fatty acid anhydride. Preferably the polymerization is carried out in the presence of an alkyl sulfonate alkali metal salt emulsifier and/or a polymerization initiator selected from the group consisting of diacyl peroxides, peroxyesters, azo compounds and their mixtures.

Description

Process for the production of vinyl chloride resin for straight processing with excellent thermal stability {Process for the Production of the Partial Highly Heat Stable Vinyl Chloride Polymer}

The vinyl chloride resin for straight processing is a resin with a wide range of applications from everyday life to industrial structural materials, from electric wires and construction pipes, profiles, sheets, and floor materials. The vinyl chloride resin for straightening process is molded into the final product by extrusion, injection or calendering process at high temperature with plasticizer. The molding process is usually performed at a high temperature of the deterioration temperature range of the vinyl chloride resin for straightening process. have. Due to the high molding processing conditions close to the deterioration temperature range of the vinyl chloride resin for straight processing, vinyl chloride resin deteriorates during product molding, resulting in discoloration, thereby preventing the formation of the desired product. If the thermal stability is poor, there is a problem that can not increase the working speed due to high temperature work.

Due to the weak thermal stability of the vinyl chloride-based resin for straight processing has been made a lot of efforts to solve this problem in the process of forming the molding process. Thus, the present invention can be broadly divided into a method of preparing a vinyl chloride-based resin having excellent thermal stability and a method of adding a thermal stabilizer for suppressing filtration in the molding process of the vinyl chloride-based resin. Among the above two methods, the method of improving the thermal stability of the resin by appropriately adjusting the manufacturing process of the vinyl chloride-based resin for straight processing of the former is not easy to apply and implement due to the problems of the resin manufacturing economy and equipment, etc. The method of using an appropriate heat stabilizer to suppress the deterioration of the resin during the straightening process of the vinyl chloride-based resin molding process is relatively easy to implement, but the chemical structure of the heat stabilizers used in the work forming step is mainly composed of organometallic compounds. The use of organometallic compounds is often limited in relation to environmental problems, and thus cannot be a preferable solution to the problem of heat discoloration.

In addition, when the organometallic thermal stabilizer is used to improve the thermal stability of the vinyl chloride-based resin for straight processing, the effect is up to a certain temperature among the processing temperatures, but when it is heated for a long time in the above temperature range, the thermal stability decreases rapidly and the organic There is a problem that the discoloration of the product is more severe due to excessive coloring phenomenon caused by the metal-based stabilizer. Due to these various technical problems, in order to improve the thermal stability of the vinyl chloride-based resin for straight processing, a method of improving the thermal stability of the resin itself by appropriately adjusting the resin manufacturing process and using a suitable stabilizer in the molding processing step It is effective to use the method together.

The present invention relates to a method for improving the thermal stability of the resin itself by appropriately adjusting the manufacturing process of the vinyl chloride-based resin for straight processing in order to improve the thermal stability of the resin that causes problems during the molding process of the vinyl chloride-based resin for straight processing. .

In order to improve the thermal stability of the vinyl chloride-based resin for straight processing, the prior art of the method for improving the thermal stability of the vinyl chloride-based resin for paste processing is described in US Pat. No. 5,139,028. A method of surface copolymerization of vinyl chloride-based resin latex surface for paste processing with methyl methacrylate by addition of methyl methacrylate is described. US Patent No. 5,319,028 (1991) filed by Japan Zeon Co., Ltd. A method of preparing a vinyl chloride-based resin for paste processing having excellent viscosity stability by homogenizing a polymethyl methacrylate resin having a molecular weight of 10,000 to 5,000,000, or a polymethyl methacrylate resin having a molecular weight of 10,000 to 5,000,000, and initiating a polymerization reaction and an emulsifier. about It is describing.

The vinyl chloride resin for straight processing is very different from the manufacturing method of vinyl chloride resin for paste processing using a low molecular weight emulsifier using a high molecular weight suspension stabilizer in manufacturing, and the particle size of the final product is also different from that of the vinyl chloride resin for straight processing. In this case, particles having a thickness of 100 to 200 µm are obtained, and the vinyl chloride resin for paste processing has a difference in that fine latex particles of 0.1 to 3 µm are finally obtained.

Proposed advanced technique to improve the thermal stability of vinyl chloride resin for paste processing. Methyl methacrylate is added to the final paste processing vinyl chloride resin latex by adding methyl methacrylate at the end of the polymerization reaction. Although a method of surface copolymerizing a rate has been proposed, this method has difficulty in performing a process in that a high reaction pressure of vinyl chloride monomer must be overcome and methyl methacrylate must be added to the reactor. In addition, the method proposed in U.S. Patent No. 5,319,028 is to inject bead or pellet-like polymethyl methacrylate resin into the manufacturing process of the vinyl chloride resin for paste processing to finally improve the stability over time of the viscosity of the vinyl chloride resin for paste processing It is aimed at.

The present invention relates to a method of adding a polymethyl methacrylate resin in the initial stage of the polymerization reaction during the manufacturing process of the vinyl chloride-based resin for straight processing with excellent heat stability during product molding processing and less heat discoloration phenomenon.

The details of the present invention are as follows.

First, 0.05 to 2.0 parts by weight of the protective colloid preparation, 0.03 to 0.2 parts by weight of the polymerization reaction initiator of the organic peroxide or sulfate system, based on 100 parts by weight of the comonomer mixture copolymerizable with water and vinyl chloride monomer or vinyl chloride monomer in the reactor 0.01 to 1.0 parts by weight of the hydrogen ion concentration regulator in the reaction phase, 0.02 to 5.0 parts by weight of methyl methacrylate resin is added to the reactor in order to improve the thermal stability of the vinyl chloride resin for straight processing, the reactor is maintained in a vacuum and vinyl chloride Alternatively, a comonomer copolymerizable with vinyl chloride is added to the reactor, and then heated and maintained at a predetermined polymerization reaction temperature. The vinyl chloride resin slurry for straight processing is removed through normal fluidized bed drying process to remove water. To prepare.

In the present invention, the vinyl chloride-based resin is a resin polymer having a composition of a vinyl chloride monomer of 70% or more by weight in the total composition of the resin, and a polymer copolymerized with a resin composed solely of vinyl chloride monomer or a copolymerizable monomer of vinyl chloride monomer. it means. Monomers copolymerizable with vinyl chloride monomers include vinyl acetate, acrylates, methacrylates, olefins such as 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 the like are widely used in conventional methods of copolymerizing vinyl chloride.

In the present invention, the protective colloid preparation used to stably maintain the process for producing a vinyl chloride resin for straight processing and to obtain stable particles has a degree of hydration of 40 to 90% by weight and a viscosity of 4% aqueous solution measured at room temperature of 10 to 50. vinyl alcohol-based resin of cps or a cellulose group having a hydroxy group of 3 to 20% by weight, and a cellulose derivative having a viscosity of 10 to 30,000 cps of a 2% aqueous solution measured at room temperature, more specifically methyl cellulose or propyl hydroxy cellulose; Or polymers of unsaturated organic acids, more specifically acrylic acid polymers, methacrylic acid polymers, itaconic acid polymers, fumaric acid polymers, maleic acid polymers, succinic acid polymers; Or gelatin may be used and mixed use thereof alone or in combination of two or more thereof is possible. The addition amount of the protective colloid preparation is appropriate to use 0.05 to 2.0 parts by weight relative to the total input monomer, more preferably at 1.0 parts by weight. When the amount of the protective colloid preparation is less than the above range for the total charged monomers, there are disadvantages in reducing the production efficiency due to the delay of the residual monomer recovery process after polymerization and remaining in the resin to reduce the transparency of the molded product.

Catalysts usable as the polymerization reaction catalyst of the present invention include organic peroxides, specifically diacyl peroxides such as dipentyl peroxide, di-3,5,5-trimethine hexa-noyl peroxide, dilauroyl peroxide, and the like. Peroxydicarbonates such as diisopropyl peroxydicarbonate, di-sec-butylperoxydicarbonate, di-2-ethylhexyl peroxydicarbonate, or tert-butylperoxy pivalate, tert-butylperoxyidecanoate Peroxy esters such as azobisisobutyronitrile, azobis-2-methylbutyronitrile, azo compounds such as azobis-2,4-dimethylbareronitrile, sulfates such as potassium percellate and ammonium percellate Are available and may be used alone or in combination of two or more. The amount of use is a factor that is determined by factors such as manufacturing process, productivity, and quality. Generally, the total amount of initiator can be used in an amount of 0.03 to 0.2 parts by weight with respect to the total amount of monomer 100, most preferably 0.05 to 0.12 parts by weight. Do. When the amount of the initiator is less than the above range, the reaction time is delayed and the productivity is lowered. When the amount of the initiator is used more than the above range, the initiator is not completely consumed during the polymerization process and remains in the final resin product to degrade the thermal stability and color quality of the resin. .

In the present invention, the composition and the amount of methyl methacrylate polymer resin which are used characteristically to improve the thermal stability of the vinyl chloride resin for straight processing are as follows. The composition of the methyl methacrylate synthesis index characteristically used in the present invention can be the use of a pure polymer of methyl methacrylate or a methyl methacrylate copolymer. Examples of methyl methacrylate and copolymerization-related monomers that are effective in improving heat discoloration of paste vinyl chloride resins include co-monomers having unsaturated double bonds, such as n-propyl acrylate, n-propyl methacrylate, and iso-propyl. Acrylate, iso-propylmethacrylate, sec-butyl acrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, lauryl acrylate, lauryl methacrylate, stearyl acrylate, stearyl meta Comonomers containing acrylate and alpha methyl styrene and containing epoxy groups include glycidyl acrylate and glycidyl methacrylate, and comonomers containing carboxyl groups include acrylic acid, methacrylic acid, itaconic acid, fumaric acid and maleic acid hydroxyl groups. Examples of comonomers containing 2-hydroxy ethyl acrylate and 2-hydroxy ethyl meta Acrylate, 2-hydroxy ethyl acrylate, 2-hydroxy butyl acrylate, 2-hydroxy butyl methacrylate. The comonomers exemplified above can be used up to 1 to 50 parts by weight of the total composition of the methyl methacrylate copolymer. In order to improve the thermal stability of the vinyl chloride resin for straight processing, the appropriate molecular weight of the methyl methacrylate polymer of the composition used in the present invention is a polymer having a molecular weight of 20,000 to 100,000 measured on the basis of the styrene polymer molecular weight measurement standard resin. Is effective. It is preferable that addition amount is 0.02-1.0 weight part with respect to 100 weight part of total injected monomers. In addition, although the addition method may be carried out collectively in the initial stage of a polymerization reaction, or it may carry out continuously together with progress of a polymerization reaction, the method of batch-injecting at the beginning of reaction is more preferable.

The above subsidiary materials are added to the reactor together with deionized water, and vacuum is applied. A comonomer copolymerizable with vinyl chloride or vinyl chloride is added and heated to carry out suspension polymerization.

Generally, the degree of polymerization of vinyl chloride-based resin is determined by the polymerization temperature, and the degree of polymerization of vinyl chloride-based resin is a factor that greatly affects the processing conditions and the physical properties of the product. Therefore, an appropriate polymerization temperature should be selected.

The general polymerization temperature of vinyl chloride-based resin produced for commercial purposes is 30 to 80 ℃. The slurry obtained after the completion of the polymerization reaction is dried in a fluidized bed dryer under normal conditions to finally produce a vinyl chloride resin for straight processing.

The sheet was prepared from the final vinyl chloride-based resin obtained by the above method, was heated in a gear oven at 200.degree. C. and measured for the time when discoloration occurred. The vinyl chloride-based resin for straight working prepared by the method of the present invention was thermally stable. It was confirmed that this was improved.

The present invention shows the following examples and comparative examples in order to explain in detail, but the present invention is not limited to these examples.

Example 1

Deionized Water 400 , 200 gr of 2-ethylhexyl peroxy dicarbonate, 13 gr of dilauryl peroxide, 80 gr of hydration and 30 cps of a 4% aqueous solution at room temperature with a viscosity of 30 gr, a styrene polymer molecular weight measurement standard sample. 150 g of polymethyl methacrylate resin having a weight average molecular weight of 60,000 measured as a reference was added to the reactor in a batch, and after vacuuming, vinyl chloride monomer 400 Was injected and the reaction temperature was raised to 58 ° C. to carry out suspension polymerization. The slurry obtained in this way is fluidized-bed drying by a conventional method, and a vinyl chloride resin for straight processing is obtained.

Comparative Example 1

Deionized Water 400 , 200 gr of 2-ethylhexyl peroxy dicarbonate, 13 gr of dilauryl peroxide, 80 gr of hydration, and 200 gr of polyvinyl alcohol having a viscosity of 4% aqueous solution at room temperature in a reactor were put into a reactor and vacuumed. Vinyl chloride monomer 400 The reaction temperature was heated up to 58 degreeC, and suspension polymerization is performed. The slurry obtained in this way is fluidized-bed drying by a conventional method, and a vinyl chloride resin for straight processing is obtained.

Comparative Example 2

Deionized Water 400 , 100 gr of 2-ethylhexyl peroxy dicarbonate, 13 gr of lauryl peroxide, 200 gr of polyvinyl alcohol having a water solubility of 80% and a viscosity of 30% at 4% aqueous solution at room temperature, and a styrene polymer molecular weight measurement standard sample. 150 g of polymetal methacrylate resin having a weight average molecular weight of 150,000 measured as a reference was added to the reactor in a batch, and after vacuuming, vinyl chloride monomer 400 The reaction temperature was heated up to 58 degreeC, and suspension polymerization is performed. The slurry obtained in this way is fluidized-bed drying by a conventional method, and a vinyl chloride resin for straight processing is obtained.

<Thermal stability evaluation>

1) Evaluation Sample Preparation

end. combination

30 weight part of dioctylphthalate and 1 weight part of heat stabilizers are added with respect to the produced vinyl chloride resin 100 for straight processing, and it mix | blends at 100 degreeC.

I. Sheet manufacturing

The sheet-formed resin of the above item is roll-milled at 190 degreeC, and the sheet | seat of thickness 0.5mm is manufactured.

2) thermal stability measurement

The prepared sheet is stopped in a gear oven at 200 ° C. and then carbonized by heat to measure the time at which discoloration occurs.

Claims (8)

In the suspension polymerization of vinyl chloride monomer to prepare a vinyl chloride resin, A method for producing a vinyl chloride resin for straight processing excellent in thermal stability, wherein 0.3 to 10 parts by weight of a methyl methacrylate resin having a molecular weight of 20,000 to 100,000 is collectively added to 100 parts by weight of a monomer at the initial stage of the polymerization reaction. The method of claim 1, A process for producing a vinyl chloride resin for straight processing with excellent thermal stability, characterized by suspending polymerization reaction of a comonomer copolymerizable with a vinyl chloride monomer with a vinyl chloride monomer. The method of claim 1, The methyl methacrylate resin is a copolymer of methyl methacrylate is a method of producing a vinyl chloride resin for straight processing excellent in thermal stability. The method of claim 1, Alkylsulfonate alkali metal salt emulsifiers are sodium undecylsulfonate, sodido dedecylsulfonate, sodip palmityl sulfonate, sony stealaryl sulfonate, sodium heptadecyl sulfonate, or sodida arsidyl sulfonate. A method for producing a vinyl chloride resin for straight processing, which has excellent thermal stability. The method of claim 1, A process for producing a vinyl chloride resin for straight processing having excellent thermal stability, using diacyl peroxides, peroxy esters, azo compounds, sulfates, or a mixture thereof as a polymerization reaction initiator. The method of claim 1, The comonomer is vinyl acetate, acrylates, methacrylates, unsaturated fatty acids, or fatty acid anhydride, The manufacturing method of the vinyl chloride resin for straight processing excellent in the thermal stability characterized by the above-mentioned. The method according to claim 1 or 2, A method for producing a vinyl chloride resin for straight processing excellent in thermal stability, comprising using 0.05 to 2.0 parts by weight of a protective colloid preparation based on 100 parts by weight of a monomer. According to claim 7, A method for producing a vinyl chloride resin for straight processing having excellent thermal stability, wherein the protective colloid preparation is selected from the group consisting of vinyl alcohol resin, cellulose derivative, organic acid polymer, and gelatin.