KR19990066358A - Process for producing straight vinyl chloride-based resin excellent in processability - Google Patents

Abstract

The present invention provides a method for producing a vinyl chloride-based resin having excellent processability by controlling the content of a low-polymerization portion and a polymer portion by a crosslinking agent by adding a small amount of crosslinking agent in the middle of the polymerization reaction during the production of vinyl chloride-based resin. It is about.

Specific examples of the crosslinking agent to be added in the middle of the polymerization reaction characteristically in order to improve the processability of the vinyl chloride resin in the present invention include allyl phthalate, allyl methacrylate, pentaerythritol triallyl ether. In order to control the content and distribution properties of the high degree of polymerization, the use of two or more kinds of crosslinking agents as well as the above-mentioned crosslinking agents is possible. The amount of addition is preferably in the range of 1000-10000 ppm.

Description

Process for producing straight vinyl chloride-based resin excellent in processability

The present invention relates to a method for producing a vinyl chloride resin.

The present invention particularly relates to a method for forming a content of 10 to 30% by weight of a low degree of polymerization resin having a degree of polymerization of 300 or less.

Vinyl chloride-based resins have a wide range of applications from everyday life to industrial structural materials, ranging from electric wires and construction pipes, profiles, sheets, and floorings. Due to the advantages of high mechanical strength and chemical stability of vinyl chloride-based resins and the ability to exhibit various physical properties by various processing molding methods, its use is diverse and carbonization during processing molding compared to other resins. There is also a problem that occurs.

Much attention and effort has been paid to supplement the weak processability of vinyl chloride resins, and many processing aids and various additives have been developed to facilitate the processing of vinyl chloride resins. Vinyl chloride-based resin is molded into a product by extrusion, injection, or calender processing together with various processing additives such as plasticizers and heat stabilizers. The productivity and work efficiency of the process will increase. Molding processability of vinyl chloride-based resin is an important factor affecting product productivity and workability, which is mainly influenced by the apparent specific gravity and porosity of vinyl chloride-based resin, gelation in the processing temperature range and melt flowability of the resin. have. As described above, the processability of the vinyl chloride-based resin is known to be related to the structure and shape of the resin particles, and in particular, the porosity of the particles affecting the mixing process of the plasticizer and the liquid additives added during the processing of the vinyl chloride-based resin. It is known that it has a large influence on the workability of vinyl chloride resin. In order to improve the porosity of the vinyl chloride-based resin, conventionally, two or more kinds of suspension stabilizers having a large difference in water solubility in suspension polymerization of the vinyl chloride-based resin are combined, or a high molecular weight suspension stabilizer and a low molecular weight emulsifier are combined. There have been many attempts to improve the porosity by controlling the form and structure of the vinyl chloride particles by controlling the interfacial activity between the vinyl chloride monomer. Although this method is effective in the injection molding processing method of compounding and extruding vinyl chloride resin, it is often not effective in molding methods such as calendar processing and press working.

Ultimately, the molding processability of the vinyl chloride-based resin is easily melted at a given processing temperature so that the flowability of the vinyl chloride-based resin can be easily manufactured. That is, as in general resin processing, in order to improve the molding processability of vinyl chloride-based resin, the melt flowability at the processing temperature should be excellent. Various additives, such as processing aids and lubricants, for improving, have been widely used in combination with vinyl chloride resins. Accordingly, much effort has been devoted to the development and blending technology of various additives for improving the molding processability of vinyl chloride resins, and has been widely applied to various industrial fields for manufacturing products using vinyl chloride resins. In the conventional vinyl chloride-based resin processing step using an additive to improve the processability has the advantage that can be easily applied according to each processing situation, while the undesirable physical properties of the molded product due to side reactions by various additives Along with the problem that causes a change, there is a burden of using expensive additives and there is a limit of the effect. In order to solve this problem, much efforts have been made to improve the molding processability of the vinyl chloride-based resin itself, so that the structure and shape of the particles are known to greatly affect the apparent specific gravity and porosity and the molding processability of the vinyl chloride-based resin. Many methods have been implemented to combine dispersants or to use low molecular weight dispersing aids in order to change.

In order to improve the processability of the resin itself in order to improve the processability during the molding process of vinyl chloride resin, 0.1 to 30 weight of methyl methacrylate resin having a methyl methacrylate content of 40% by weight or more during the polymerization of vinyl chloride resin. Method of adding by adding% (US Pat. No. 4,668,740, Mitsubishi Rayon Co., Ltd.) and polymerizing di-acrylate or di-methyl acrylate monomer modified with bisphenol A while continuously adding the vinyl chloride resin during polymerization (US Patent No. 4,458,061, Kanegachichi Co., Ltd., a low-molecular-weight vinyl chloride-based resin prepared in step 1 by adding a thiol- or dithiol-based chain transfer agent in a step of polymerizing vinyl chloride-based resin, and Method of preparing a vinyl chloride-based resin in a conventional manner by adding a vinyl chloride-based resin to the reactor together with a vinyl chloride-based monomer ( National Patent No. 4,267,084, Tokuyama Soda, 1979; J of Appl.Polym.Sci.Vol. 51, p.555-561, p.749-753, p.755-759, p.1161-1169, 1994 Tokuyama Soda Co. Ltd.) and the like, and in the U.S. patent of BF Goodrich, the vinyl chloride resin having a low Inherent Viscosity of 0.35 to 0.65 measured by the test method of ASTM1243 in order to improve the processability of the vinyl chloride resin. And a vinyl chloride resin kneading processing method excellent in mechanical properties and processability by kneading and processing (US Patent No. 4,267,084, "Vinly Chloride Polymer Blend Composition", 1979). In addition, the US patent of Mitsubishi Rayon Company Ltd. claims a PVC polymerization composition having a low polymerization degree PVC content of 300 to 700 of 5 wt% or more and a high polymerization degree portion of 700 or more polymerization degrees (US Pat. No. 4,668,740 Vinyl) Chloride Resin Composition 1987).

As described above, the prior arts provide a method of adding an additive to the vinyl chloride resin during the polymerization reaction or melting characteristics of the resin to impart activity during the processing of the vinyl chloride resin for the purpose of improving the processability of the vinyl chloride resin. It can be summarized as a method of forming low molecular weight portions to improve. As a technical method for forming low-polymerization moieties for the purpose of improving the processability of vinyl chloride-based resins, Japanese Laid-Open Patent 278,207 (1995) of Sam Hwa Chemical Co., Ltd. changed the temperature of PVC polymerization reaction and two kinds of initiator combinations with different half-lives. The method of adjusting the degree of polymerization distribution characteristic to form workability of the resin is described.

However, the technical methods proposed above to improve the processability of the vinyl chloride-based resin, the method of adding an active additive during the polymerization during the polymerization process is a side effect of severe colorability due to the side reaction between the reactants and additives such as vinyl chloride monomer Depending on the chemicals added together, there is a disadvantage in that the selection of processing additives such as stabilizers used in the processing step is limited. As a method of minimizing such side effects, it is preferable to adjust the content of the low-polymerization portion of the polymerization degree characteristic of the vinyl chloride-based resin to balance the processing and mechanical properties. As a prior art method of controlling the content of the low degree of polymerization, a method of changing the reaction temperature in the vinyl chloride resin polymerization reaction, adding a chain transfer agent in the polymerization, or kneading with the low degree of polymerization vinyl chloride resin has been proposed. . Looking at these prior arts, in the case of a method of changing the polymerization temperature, it is difficult to control the reaction temperature during the polymerization process by changing the reaction temperature drastically by 10 ° C. or more, and adding a chain transfer agent during the polymerization. In the case of the method has a hassle to go through a two-step polymerization process, and the kneading method with a low polymerization resin has a disadvantage in that workability is lowered due to non-uniform melting of the resin particles in the practical application.

The present invention provides a method for producing a vinyl chloride-based resin having excellent processability by controlling the content of a low-polymerization portion and a polymer portion by a crosslinking agent by adding a small amount of crosslinking agent in the middle of the polymerization reaction during the production of vinyl chloride-based resin. It is about.

In the method of the present invention, 0.05 to 2.0 parts by weight of the protective colloid preparation and 0.03 to 0.2 of the organic peroxide or sulfate-based polymerization initiator are first added to 100 parts by weight of the copolymer of water and a vinyl chloride monomer or a comonomer mixture copolymerizable with vinyl chloride monomer. 0.01 parts by weight to 1.0 parts by weight of the hydrogen ion concentration regulator in the polymerization reaction phase is added to the reactor and reacted while adjusting the polymerization reaction temperature by the method proposed in the present invention to obtain a vinyl chloride resin slurry. The obtained vinyl chloride resin slurry is removed by water through a normal fluidized bed drying process to prepare a vinyl chloride resin having excellent processability.

In the present invention, the vinyl chloride resin is a resin polymer having a composition of vinyl chloride monomer of 70% or more by weight in the total composition of the resin, and a polymer copolymerized with a resin composed of vinyl chloride monomer or a monomer copolymerizable with vinyl chloride monomer. it means. Monomers copolymerizable with vinyl chloride monomers include vinyl acetate, acrylates, methacrylates, olefins such as ethylene and propylene, unsaturated fatty acids such as acrylic acid, methacrylic acid, itaconic acid and maleic acid, and anhydrides of these fatty acids. In general, they are widely used in the conventional method 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 at room temperature of 10 to 50 cps. A vinyl alcohol-based resin or a polymer of cellulose or unsaturated organic acid having a viscosity of 10 to 30,000 cps in a 2% aqueous solution measured at room temperature with 3 to 20% by weight of a propyl group hydroxide may be used. More specifically, an acrylic acid polymer and a methacrylic acid polymer , Itaconic acid polymers, fumaric acid polymers, maleic acid polymers, succinic acid polymers, or gelatin can be used, and their use alone or in combination of two or more thereof is possible. The addition amount is appropriate to use 0.05 to 2.0 parts by weight based on 100 parts by weight of the total input monomer, and more preferably at 1.0 parts by weight. If the added amount is less than the above range for the total input monomer, it is difficult to maintain the stability of the resin manufacturing process, and when used in excess, the transparency of the molded product due to the decrease in the production efficiency due to the delay of the residual monomer recovery process after polymerization and the residual in the final resin There is a disadvantage of lowering.

Catalysts usable as the polymerization catalyst of the present invention include organic peroxides, specifically, dicumyl peroxide, dipentyl peroxide, di-3,5,5-trimethyl hexanoyl peroxide, dilauroyl peroxide, and the like. Diacyl peroxides, peroxydicarbonates such as diisopropyl peroxydicarbonate, di-sec-butyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, or t-butyl peroxy pivalate, t-butyl peroxide Peroxy esters such as oxy nedecanoate and azobis-2,4-dimethylvaleronitrile include sulfates such as azo compounds, potassium persulfate and ammonium persulfate, and these may be used alone or in combination of two or more thereof. It is possible to use. The amount of use 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 based on 100 parts by weight of the total monomer input, most preferably 0.05 to 0.12 parts by weight. This is preferred. When the amount of the initiator is less than the proper amount, the reaction time is delayed and the productivity is lowered. When the amount of the initiator is used more than the proper amount, the initiator is not completely consumed during the polymerization process and remains in the final resin product to reduce the thermal stability and color quality of the resin.

Specific examples of the crosslinking agent to be added in the middle of the polymerization reaction characteristically in order to improve the processability of the vinyl chloride resin in the present invention include allyl phthalate, allyl methacrylate, pentaerythritol triallyl ether. In order to control the content and distribution properties of the high degree of polymerization, the use of two or more kinds of crosslinking agents as well as the above-mentioned crosslinking agents is possible. The amount of addition is preferably in the range of 1000-10000 ppm. In order to improve the processability of the vinyl chloride-based resin proposed in the present invention, when the above-mentioned crosslinking agents are added at 1000 ppm or less which is less than or equal to the above range, the effect of improving the processability is weak and the effect is not expressed during molding of the resin. When it adds more than 10000 ppm or more, the problem of delaying a polymerization reaction time and the problem of resin processability falling arises.

After a certain period of time, the auxiliary raw materials described above are added in a batch to maintain the predetermined polymerization reaction temperature, and then the reaction is stopped when the predetermined conversion rate is reached.

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 industrial purposes is 30 to 80 ℃. The slurry obtained after completion of the polymerization reaction is dried in a fluidized bed dryer under normal conditions to produce a vinyl chloride resin for final straight working.

As a result of measuring the fusion time and the extrusion amount of the final vinyl chloride resin obtained by the above method as a measure of processability, it was confirmed that the processability and the extrusion amount of the vinyl chloride resin were significantly improved.

Although the following Examples and Comparative Examples are shown to specifically illustrate the present invention, the present invention is not limited to these examples.

Example 1

Deionized water, 400 l, 2- ethylhexyl peroxydicarbonate 100 gr, dilauryl peroxide 13 gr, moisture content of 80% and a bulk input to a 4% aqueous solution of polyvinyl alcohol 200 gr a viscosity of 30 cps at room temperature of the reactor After the addition of vacuum, 300 l of vinyl chloride was added, the polymerization temperature was raised to 58 ° C., and the reaction proceeded. After 40% conversion, 450 gr of diallylphthalate was added to continue the reaction. It is dried in a fluidized bed drier to obtain a vinyl chloride resin.

Example 2

Deionized water, 400 l, 2- ethylhexyl peroxydicarbonate 100 gr, dilauryl peroxide 13 gr, moisture content of 80% and a bulk input to a 4% aqueous solution of polyvinyl alcohol 200 gr a viscosity of 30 cps at room temperature of the reactor After the addition of vacuum, 300 l of vinyl chloride was added, the polymerization temperature was raised to 58 ° C., and the reaction was continued. After 40% conversion, 450 g of allyl methacrylate was added to continue the reaction. In the method of drying in a fluidized bed dryer to obtain a vinyl chloride resin.

Example 3

Deionized water, 400 l, 2- ethylhexyl peroxydicarbonate 100 gr, dilauryl peroxide 13 gr, moisture content of 80% and a bulk input to a 4% aqueous solution of polyvinyl alcohol 200 gr a viscosity of 30 cps at room temperature of the reactor After adding vacuum and adding 300 l of vinyl chloride, the polymerization temperature was raised to 58 ° C., and the reaction was continued. After 40% of conversion, Pentacrythriol triallyl ether 450 gr was added to continue the reaction. Drying in a fluidized bed drier in a conventional manner yields a vinyl chloride resin.

Comparative Example 1

Deionized water, 400 l, 2- ethylhexyl peroxydicarbonate 100 gr, dilauryl peroxide 13 gr, moisture content of 80% and a bulk input to a 4% aqueous solution of polyvinyl alcohol 200 gr a viscosity of 30 cps at room temperature of the reactor After the addition of vacuum, 300 l of vinyl chloride was added, the polymerization temperature was raised to 58 ° C., and the reaction was carried out. After 40% conversion, 150 gr of diallylphthalate was added to continue the reaction. It is dried in a fluidized bed drier to obtain a vinyl chloride resin.

Comparative Example 2

Deionized water, 400 l, 2- ethylhexyl peroxydicarbonate 100 gr, dilauryl peroxide 13 gr, moisture content of 80% and a bulk input to a 4% aqueous solution of polyvinyl alcohol 200 gr a viscosity of 30 cps at room temperature of the reactor After the addition of vacuum, 300 l of vinyl chloride was added, the polymerization temperature was raised to 58 ° C., and the reaction was continued. After 40% conversion, 300 gr of diallylphthalate was added to continue the reaction. It is dried in a fluidized bed dryer by the method to obtain a vinyl chloride resin.

Comparative Example 3

Deionized water, 400 l, 2- ethylhexyl peroxydicarbonate 100 gr, dilauryl peroxide 13 gr, moisture content of 80% and a bulk input to a 4% aqueous solution of polyvinyl alcohol 200 gr a viscosity of 30 cps at room temperature of the reactor After the addition of vacuum, 300 l of vinyl chloride was added, the polymerization temperature was raised to 58 ° C., and the reaction was carried out. After 40% of conversion, diallylphalate 650 gr was added to continue the reaction. It is dried in a fluidized bed drier to obtain a vinyl chloride resin.

Comparative Example 4

Deionized water, 400 l, 2- ethylhexyl peroxydicarbonate 100 gr, dilauryl peroxide 13 gr, moisture content of 80% and a bulk input to a 4% aqueous solution of polyvinyl alcohol 200 gr a viscosity of 30 cps at room temperature of the reactor After adding vacuum and adding 300 l of vinyl chloride, the polymerization temperature was raised to 52 ° C., and the reaction was continued. After 40% conversion, the slurry obtained was dried in a fluidized bed dryer in a conventional manner to obtain a vinyl chloride resin. Get

Measurement results of basic resin properties and processability Metric unit Example 1 Example 2 Example 3 Apparent specific polymerization degree Average particle size thermal stability g / ccμmmin 0.4931,320 137 70 0.481,300 145 65 0.481,280 160 63 Reaction time Hr 7.3 8 8.5 Extrusion quantity extrusion TQ g / minNm- Good 36.05,800 Normal 36.55,500Normal

(continue)

Metric unit Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Apparent specific polymerization degree Average particle size thermal stability g / ccμmmin 0.4591,080 132 55 0.4711,170 143 63 0.4621,680 132 60 0.4581,380 155 70 Reaction time Hr 6.5 7.3 7.5 9.1

Use of the method of the present invention improves the processability of the vinyl chloride-based resin and significantly increases the amount of extrusion per unit time, thereby increasing productivity.

Claims (5)

A method of polymerizing a vinyl chloride monomer in the presence of a protective colloid preparation, a polymerization initiator, and a hydrogen ion concentration regulator to form a content of a low polymerization degree portion of a polymerization degree of 300 or less in a polymerization degree distribution characteristic of a vinyl chloride resin at 10 to 30% by weight. A crosslinking agent is collectively added when the polymerization conversion rate of a vinyl chloride resin is 10 to 60%, The manufacturing method of a vinyl chloride resin characterized by the above-mentioned. The method of claim 1, Method to use diallyl phthalate, allyl methacrylate, pentaerythritol triallyl ether as a crosslinking agent added. The method of claim 1, A method of using a vinyl alcohol-based resin having a hydration degree of 40 to 90% by weight and a viscosity of 10 to 50 cps at room temperature as a protective colloid preparation. The method of claim 1, A method of using propyl cellulose, wherein the propyl hydroxide is 3 to 20% by weight and the viscosity of a 2% aqueous solution at room temperature is 10 to 30,000 cps as a protective colloid preparation. In the vinyl chloride resin, A vinyl chloride resin containing 10 to 30% by weight of a low polymerization degree portion of a degree of polymerization of 300 or less, characterized in that the polymerization conversion rate is 10 to 60% to produce a cross-linking agent in a batch.