KR100398736B1 - Preparation method of straight vinyl chloride-based resin with excellent processability - Google Patents

Abstract

PURPOSE: A method for preparing a straight vinyl chloride-based resin and a vinyl chloride-based resin are provided, to improve processability by controlling the content of the part of a low degree of polymerization due to a polymerization temperature and a polymer part due to a crosslinking agent. CONSTITUTION: The method comprises the step of polymerizing a vinyl chloride monomer in the presence of a protective colloid aid, a polymerization initiator and a pH controller to prepare a vinyl chloride-based resin with making the content of a low degree of polymerization part having a middle degree of polymerization of 300 or less be 10-30 wt%, wherein a crosslinking agent is added at a time when the polymerization conversion rate of a vinyl chloride resin is 10-60 %. Preferably the crosslinking agent is diallyl phthalate, ally methacrylate or pentaerythritol triallyl ether; and the protective colloid aid is a vinyl alcohol-based resin having a degree of hydration of 40-90 wt% and a viscosity of 4% aqueous solution at a room temperature of 10-50 cps.

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 polymerization resin having a degree of polymerization of 300 or less.

Vinyl chloride-based resin is a resin having a wide range of applications from everyday life to industrial structural materials, ranging from wire and building pipe profiles, sheets, and flooring materials. Due to its advantages in terms of physical properties such as 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 processed compared to other resins. There is also a problem in that carbonization occurs during molding.

Much attention and effort has been paid to supplement the weak processability of vinyl chloride-based resins, and many processing aids and various additives have been developed to facilitate the processing of vinyl chloride-based resins. Vinyl chloride-based resin is molded into a product by extrusion, injection, or calendar processing together with various processing additives such as plasticizers and heat stabilizers.In this process, the product must be easily melted at the processing temperature of the resin to have excellent flowability of the resin. The productivity and work efficiency of the manufacturing process will increase. Molding processability of the 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 the vinyl chloride-based resin, and the gelability and melt flowability of the resin in the processing temperature range. It is known to receive. 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. Particularly, 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 the vinyl chloride resin has a great influence on the processability. 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 surface activity between the vinyl chloride monomers. Although this method is effective in the injection molding processing method of compounding and extruding vinyl chloride-based occasional, 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, in order to improve the molding processability of the vinyl chloride-based resin as in general resin processing, the melt flowability at the processing temperature should be excellent. In order to achieve this object, conventionally, the molding of the vinyl chloride-based resin is mainly performed in the product molding step. Various additives such as processing aids and lubricants for improving workability 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 producing 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 reaction of the molded product due to side reactions by various additives Along with the problem that causes a change in physical properties, 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 resin itself, and the structure of the particles known to greatly affect the apparent specific gravity and porosity, and the molding processability of the vinyl chloride resin. Many methods have been implemented to combine dispersants or to use low molecular weight dispersing agents to change the form.

In order to improve the processability of the resin itself in order to improve the processability during the molding process of the vinyl chloride resin, 0.1 to 30 methyl methacrylate resin having a methyl methacrylate content of 40% by weight or more during the polymerization of the vinyl chloride resin. Method of preparing by adding by weight% (US Pat. No. 4,668,740, Mitsubishi Rayon Co., Ltd.) and polymerization of bisphenol A-modified di- or di-methyl acrylate monomers continuously during the polymerization of vinyl chloride resin (US Patent No.4.458,061 to Kanegafuchi Co., Ltd., a low-molecular-weight vinyl chloride-based resin was prepared by adding a thiol- or dithiol-based chain transfer agent in one step of vinyl chloride-based resin polymerization, A vinyl chloride-based resin is prepared in a conventional manner by introducing a molecular weight vinyl chloride-based resin into a reactor together with a vinyl chloride-based monomer. Law (US Pat. 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 U.S. Patent of B. F Goodrich Co., Ltd., have a low intrinsic viscosity measured by the test method of ASTM1243 as low as 0.35 to 0.65 in order to improve the processability of vinyl chloride resin. By kneading with a vinyl chloride-based resin, a vinyl chloride-based resin kneading processing method having excellent mechanical properties and workability is described (US Patent No. 4,267,084, "Vinly Chlolide Polymer Blend Composition", 1979). In addition, the US patent of Mitsubishi Rayon Company Ltd. has a patent for 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 during a vinyl chloride-based resin polymerization reaction or a melting property of the resin to impart an activity during the processing of the vinyl chloride-based resin to improve the processability of the vinyl chloride-based resin. It can be summarized as a method of forming the low molecular weight portion to improve the. As a technical method for forming low-polymerization moieties for the purpose of improving the processability of vinyl chloride resins. Japanese Laid-Open Patent Publication No. 278,207 (1995) discloses a method of combining two kinds of initiators having different half-lives and a method of controlling the degree of polymerization distribution by changing the PVC polymerization temperature to form workability of the resin.

However, in view of the technical methods proposed above to improve the processability of vinyl chloride-based resins, the method of adding an additive having high activity during processing during polymerization may have side effects such as adverse reactions due to side reaction between reactants and additives such as vinyl chloride-based monomers. 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 characteristics 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 because a change in the reaction temperature is rapidly changed to 10 ° C. or more, and a chain transfer agent is added during the polymerization. In the case of the method, there is a hassle to undergo a two-step polymerization process, and the kneading method with the low-polymerization resin has a disadvantage in that workability is lowered due to uneven melting of the resin particles in actual application.

According to the present invention, a small amount of crosslinking agent by polymerization temperature and a polymer portion by crosslinking agent are added by adding a small amount of crosslinking agent at the time of polymerization reaction during the production of vinyl chloride resin, that is, when the polymerization conversion rate of vinyl chloride resin is 10 to 60%. It relates to a method for producing a vinyl chloride-based resin excellent in processability by controlling the.

The present invention is 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. The present invention provides a method for producing a vinyl chloride resin, wherein the crosslinking agent is collectively added when the polymerization conversion rate of the vinyl chloride resin is 10 to 60%.

The present invention also provides a vinyl chloride resin containing 10 to 30% by weight of a low polymerization degree portion of a polymerization degree of 300 or less, characterized in that the crosslinking agent is prepared at a time when the polymerization conversion rate is 10 to 60%.

In the method of the present invention, 0.05 to 2.0 parts by weight of a protective colloid preparation and 0.03 to 0.2 parts of an organic peroxide or sulfate-based polymerization initiator are first added to 100 parts by weight of a copolymer of water and a vinyl chloride monomer or a comonomer mixture copolymerizable with vinyl chloride monomer. 0.01-1.0 parts by weight of the hydrogen ion concentration regulator in the weight part 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-based resin is a resin polymer having a content of vinyl chloride monomer of 70% by weight or more in the total composition of the resin, and means a polymer copolymerized with a resin made of vinyl chloride monomer or a monomer copolymerizable with vinyl chloride monomer. do.

Monomers copolymerizable with vinyl chloride monomers include vinyl acetate, acrylates, methacrylates, olefins such as ethylene 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-based 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. Vinyl alcohol-based resins, or polymers of propyl hydroxy cellulose or unsaturated organic acids 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 propyl hydroxide, may be used. More specifically, acrylic acid polymer and methacryl Acid polymers, itaconic acid polymers, fumaric acid polymers, maleic acid polymers, succinic acid polymers, or gelatin can be used, and these can be used alone or in combination of two or more thereof. The addition amount is appropriate to use 0.05 to 2.0 parts by weight with respect to 100 parts by weight of the total monomer input, more preferably at 1.0 parts by weight level is effective. If the added amount is less than the above range with respect to the total input monomers, 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 reaction catalyst of the present invention include organic peroxides, specifically, dicumyl peroxides such as dicumyl peroxide, dipentyl peroxide di-3,5,5-trimethyl hexanoyl peroxide and dilauroyl peroxide. Oxides, peroxydicarbonates such as diisopropyl peroxydicarbonate, di-sec-butylperoxydicarbonate, di-2-ethylhexyl peroxydicarbonate, or t, -butylperoxy pivalate, t-butylperoxy Peroxy esters such as nadecanoate, azo compounds such as azobis-2,4-dimethylvaleronitrile, and sulfates such as potassium, persulfate and ammonium persulfate, and these alone or in combination of two or more thereof It can be used by. The amount of use is determined by factors such as manufacturing process, productivity, quality, etc. Generally, the total amount of initiator can be used in an amount of 0.03 to 0.2 parts by weight, most preferably 0.05. To 0.12 parts by weight based on 100 parts by weight of the total monomer input. The use of wealth 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 specifically added in the middle of the polymerization reaction in order to improve the processability of the vinyl chloride resin in the present invention include diallyl phthalate, allyl methacrylate, pentaerythritol triallyl ether as the allyl compound. For the purpose of controlling the content and distribution properties of the high degree of polymerization, it is possible to use not only the above-mentioned crosslinking agents alone but also two or more kinds of mixtures. It is preferable that the range of addition amount is 1000-10,000 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 in an amount of 1,000 ppm or less which is less than or equal to the above range, the effect of improving the workability is weak and the effect is not exerted during molding processing of the resin. When 10,000 ppm or more is added, the problem of delaying the polymerization reaction time and the deterioration of workability of the resin occur.

After the reaction for a certain period of time, the above-mentioned auxiliary raw materials are collectively added to the reaction while maintaining the predetermined polymerization reaction temperature, and 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 reaction 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.

The general polymerization temperature of vinyl chloride resin produced for industrial purposes is 30-80 degreeC. 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

400 l of deionized water, 100 gr of 2-ethylhexyl peroxydicarbonate, 13 gr of dilauryl peroxide, 200 gr of polyvinyl alcohol having a viscosity of 30% at 4% aqueous solution at 80% hydration in a reactor After adding vacuum, 300 l of vinyl chloride was added and the polymerization temperature was raised to 58 ° C. to proceed with the reaction. When the conversion was over 40%, 450 gr of diallyl phthalate was added to continue the reaction. It is dried in a fluidized bed drier in a conventional manner to obtain a vinyl chloride resin.

Example 2

400 l of deionized water, 100 gr of 2-ethylhexyl peroxydicarbonate, 13 gr of dilauryl peroxide, 200 gr of polyvinyl alcohol having a viscosity of 30% at 4% aqueous solution at 80% hydration in a reactor After adding vacuum, 300 l of vinyl chloride was added, the polymerization temperature was raised to 58 ° C., and the reaction was continued. After 40% of conversion, allyl methacrylate 450 gr was added to continue the reaction. Is dried in a fluidized bed dryer in a conventional manner to obtain a vinyl chloride resin.

Example 3

400 l of deionized water, 100 gr of 2-ethylhexyl peroxydicarbonate, 13 gr of dilauryl peroxide, 200 gr of polyvinyl alcohol having a viscosity of 30% at 4% aqueous solution at 80% hydration in a reactor After adding vacuum, 300 l of vinyl chloride was added, the polymerization temperature was raised to 58 ° C., and the reaction was continued. When the conversion rate was 40%, 450 gr of pentaerythritol triallyl ether was added to continue the reaction. The slurry is dried in a fluidized bed dryer in a conventional manner to obtain a vinyl chloride resin.

Comparative Example 1

400 l of deionized water, 100 gr of 2-ethylhexyl peroxydicarbonate, 13 gr of dilauryl peroxide, and 200 gr of polyvinyl alcohol having a viscosity of 30 cps at 80% hydration and a 4% aqueous solution at room temperature After the addition and vacuum, 300 l of vinyl chloride was added and the polymerization temperature was raised to 58 ° C. to proceed with the reaction. When the conversion rate was 40%, 150 gr of diallyl phthalate was added to continue the reaction. It is dried in a fluidized bed drier in a conventional manner to obtain a vinyl chloride resin.

Comparative Example 2

400 l of deionized water, 100 gr of 2-ethylhexyl peroxydicarbonate, 13 gr of dilauryl peroxide, 200 gr of polyvinyl alcohol having a viscosity of 30% at 4% aqueous solution at 80% hydration in a reactor After adding a vacuum, 300 l of vinyl chloride was added, the polymerization temperature was raised to 58 ° C., and the reaction was continued. When the conversion rate was 40%, 300 gr of diallyl phthalate was added to continue the reaction. It is dried in a fluidized bed drier in a conventional manner to obtain a vinyl chloride resin.

Comparative Example 3

400 l of deionized water, 100 gr of 2-ethylhexyl peroxydicarbonate, 13 gr of dilauryl peroxide, 200 gr of polyvinyl alcohol having a viscosity of 30% at 4% aqueous solution at 80% hydration in a reactor After adding 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, 650 gr of diallyl phthalate was added to continue the reaction. In the method of drying in a fluidized bed dryer to obtain a vinyl chloride resin.

Comparative Example 4

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

TABLE 1

Measurement results of basic resin properties and processability

(continue)

By using the method of the present invention, the processability of the vinyl chloride-based resin is improved, and the amount of extrusion per unit time is remarkably improved, thereby increasing productivity.

Claims (5)

In 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 the 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 vinyl chloride resin is 10 to 60%, The manufacturing method of vinyl chloride resin characterized by the above-mentioned. The process according to claim 1, wherein diallyl phthalate, allyl methacrylate, pentaerythritol triallyl ether are used as the crosslinking agent to be added. The method of using a vinyl alcohol-based resin according to claim 1, wherein the protective colloid is used to prepare a vinyl alcohol resin having a degree of hydration of 40 to 90 wt% and a viscosity of 4% aqueous solution at 10 to 50 cps at room temperature. The method according to claim 1, wherein the protective colloid is prepared using 3-20 wt% of propyl hydroxide and 10-30,000 cps of a 2% aqueous solution at room temperature. 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 crosslinking agent is added at a time when the polymerization conversion rate is 10 to 60%.