JPS61283603A - Production of chlorinated vinyl chloride resin - Google Patents

Abstract

PURPOSE:To obtain the titled resin which is not colored during heat molding and can give a transparent molding, by polymerizing vinyl chloride in an aqueous medium in the presence of a specified copolymer, a water-soluble cellulose derivative, and an oil-soluble polymerization catalyst and chlorinating the product. CONSTITUTION:Vinyl chloride is dispersed in an aqueous medium. To this aqueous dispersion, polyacrylic acid, polymethacrylic acid or a copolymer of acrylic acid with methacrylic acid is added together with a water-soluble cellulose derivative, and the vinyl chloride is polymerized in the presence of an oil-soluble polymerization catalyst. The vinyl chloride resin obtained in this way is chlorinated. The acryls added in polymerization are preferably those obtained by polymerizing (meth)acrylic acid and having a MW of 5,000-600,000. It is preferable that 0.03-0.2pt.wt. water-soluble cellulose derivative and 0.03-0.3pt.wt. acryl are used per 100pts.wt. monomer to be polymerized.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a chlorinated vinyl chloride resin. An object of the present invention is to produce a chlorinated vinyl chloride resin that remains colorless and gives a transparent molded product when heated for molding.

Chlorinated vinyl chloride resin (hereinafter referred to as CPVC) is vinyl chloride resin (hereinafter referred to as PvC)
It is made by chlorinating. CPVC has the good characteristics of PvC, and is expected to have a wide range of uses as it improves the shortcomings of PvC ◇To be more specific, CPVC has excellent weather resistance, fire resistance, and chemical resistance, just like PvC. There is. Furthermore, PVC cannot be used at temperatures above 60-70°C due to its low heat distortion temperature, which has been considered a drawback, but CPVC has a heat distortion temperature that is 20-40°C higher than PVC. Therefore, it was evaluated as having improved heat resistance of PvC. Therefore, CPVC is about to have wider applications than PvC.

However, conventional CPVC was not suitable for the new applications being developed. The reason is that when conventional CPVC is molded for such applications, the CPVC already turns from yellow to brown in the early stages of heating.
This is because it could not be colorless and transparent. To be more specific, the application is for things that require colorless transparency such as electronic component cases and display boards, but CP
When VC was heated in an attempt to mold it, the CPVC was already partially decomposed and colored yellow when it began to melt, and could not become colorless and transparent. Therefore, as mentioned above, it could not be used for applications requiring colorlessness. Therefore, in order to find new uses, it was necessary to create a CPVC that is free from initial coloring and forms a colorless and transparent melt when melted by heating.

According to the literature, Japanese Patent Publication No. 43-18553 states that Pv
We propose an improvement to the C chlorination process. According to the proposal, suspending PvC in an aqueous medium in the presence of a hydrochloromethylene compound and further chlorinating PvC in the presence of an acrylic acid polymer improves the chlorination process. be.

With this proposal, it is possible to obtain a CPVC which does not have any initial coloration and gives a colorless and transparent melt.

However, the above proposal requires a special chlorine-containing swelling agent such as a hydrochloromethylene compound, so it is not easy to implement, and the swelling of PvC tends to cause various troubles. Since the swelling agent must be removed, there is a drawback that the operation becomes complicated. Therefore, this inventor attempted to eliminate the initial coloring of CPVC using an even simpler method. This inventor conducted extensive research on a method to prevent the initial coloring of CPVC and to make CPVC a colorless and transparent melt. I did it. As a result, among the acrylic acid polymers described in the above-mentioned Japanese Patent Publication No. 43-18553, specific ones, namely polyacrylic acid, polymethacrylic acid, or copolymers of acrylic acid and methacrylic acid, were Furthermore, if this is added together with a water-soluble cellulose derivative to an aqueous medium during the suspension polymerization of vinyl chloride, the PvC thus obtained is further chlorinated to form cp.
It was found that when VC was used, CPVC became stable against heat, and there was no initial coloration upon heating, producing a colorless and transparent melt. This invention was made based on such knowledge.

This invention involves dispersing vinyl chloride in an aqueous medium, adding a water-soluble cellulose derivative along with polyacrylic acid, polymethacrylic acid, or a copolymer of acrylic acid and methacrylic acid to the aqueous medium, and dispersing the oil-soluble polymerization catalyst. The present invention relates to a method for producing a chlorinated vinyl chloride resin, which is characterized by polymerizing vinyl chloride in the presence of and chlorinating the vinyl chloride resin thus obtained.

Dispersing vinyl chloride in an aqueous medium and polymerizing the vinyl chloride in the presence of an oil-soluble catalyst to make PvC is known as suspension polymerization of vinyl chloride.

It is also known to chlorinate the PVC thus obtained to produce CPVC. Therefore, this invention provides a method for obtaining CPVC by adding a polymer or copolymer of acrylic acid or methacrylic acid to an aqueous medium during suspension polymerization of PVC, and chlorinating the PVC thus obtained. I can say that. Although it is natural that substances added to the aqueous medium during the polymerization process affect the properties of the polymer, it is unlikely that the effect will extend even after chlorination and improve the thermal stability of CPVC. , a completely unexpected effect.

Furthermore, polyacrylic acid/acid, polymethacrylic acid, or a copolymer of acrylic acid and methacrylic acid (hereinafter referred to as
All of these (collectively called acrylics) are water-soluble, and cellulose derivatives (hereinafter referred to as derivatives) are also water-soluble, so they cannot be added to an aqueous medium. Even if acrylic or derivatives are added during polymerization, it is thought that they will be removed from PvC or CPVC by the water washing operation that is always performed after the polymerization reaction or chlorination reaction. Therefore, even if acrylic or derivatives are added during polymerization, It is thought that this is unlikely to be useful for stabilizing chlorinated vinyl chloride resins. However, the fact is completely contrary to this, and the addition of acrylic and derivatives to the aqueous medium during suspension polymerization has the effect of thermally stabilizing CPVC, which is considered completely unexpected.

The most important feature of this invention is what is added to the aqueous medium during polymerization. One of them is acrylic. Acrylic is a polymer obtained by polymerizing acrylic acid or methacrylic acid. In this case, the monomer m is not an ester but an acid itself. Polymerization can be carried out by various methods. For example, it can be easily obtained by dissolving acrylic alcohol in an organic solvent, adding a polymerization initiator to the solution, and carrying out an ordinary solution polymerization method. As the polymerization initiator, for example, benzoyl peroxide can be used. Acrylic has a molecular weight of 5,000~
Preferably, a value within the range of 600,000 is used.

In this invention, another thing added to the aqueous medium is a derivative. The derivative is a known dispersant used in the suspension polymerization process of vinyl chloride. The derivative is, for example, hydroxyalkylated cellulose obtained by adding alkylene oxide to cellulose, such as hydroxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose. In addition, examples of cellulose include carboxymethyl cellulose,
Methylcellulose can also be used. Many of the derivatives are water-soluble.

The derivative, as mentioned above, is one of the known dispersants used in suspension polymerization of vinyl chloride.

However, the derivatives have never been used as dispersants with acrylics. This is because acrylic is not included in what is generally considered a dispersant. Furthermore, since acrylic is not in the form of an ester or salt, but in the form of an acid itself, it is unlikely that the acid form would aid in dispersion.

In the present invention, the derivative is used in an amount of 0.01 to 0.5 part, and the acrylic is used in an amount of 0.01 to 0.5 part, based on 100 parts by weight of the monomer to be polymerized. Among these, preferred is a range of 0.03 to 0.2 part of the derivative and a range of O, Oa part to 0.3 part of the acrylic.

As mentioned above, this invention method can be said to be a method characterized by adding acrylic together with a specific dispersant into an aqueous medium in the suspension polymerization method of vinyl chloride. Therefore, the suspension polymerization of vinyl chloride will be briefly explained below.

In suspension polymerization, an oil-soluble polymerization catalyst is used.

The oil-soluble polymerization catalyst refers to a polymerization catalyst that is soluble in hydrocarbons such as benzene. Such catalysts include, for example, peroxides such as benzoyl peroxide, lauroyl peroxide, azobisisobutyronitrile, dialkyl peroxydicarbonates, and the like. As the catalyst, the above catalysts may be used alone, or two or more catalysts may be used in combination. The amount is vinyl chloride 1
It is usually used in an amount of 0.02 to 0.02 parts by weight.

These catalysts and methods of using them are all well known, and the present invention uses what is known as is as far as the use of the catalyst is concerned.

With the exception of vinyl chloride, all of the materials used in the polymerization process of this invention are liquids or solids at normal temperature and pressure. Only vinyl chloride is a gas at normal temperature and pressure, so when carrying out this invention, first put water in an autoclave, then add the above-mentioned acrylic, derivative, and oil-soluble polymerization catalyst, and stir well. Make an aqueous medium.

After that, the autoclave is sealed, and then the air inside the autoclave is removed by vacuum suction, and then vinyl chloride is added to a predetermined amount to initiate polymerization. Thereafter, the temperature inside the autoclave is raised while stirring well, and the polymerization is continued in this state. This is the process of obtaining PVC.

The monomer to be polymerized in this invention is vinyl chloride. This invention is applicable not only to the polymerization of vinyl chloride alone, but also to the copolymerization of vinyl chloride and other monomers, and to the polymerization of vinyl chloride into other polymers or copolymers that do not contain vinyl chloride. It can also be used for graft polymerization.

For example, other monomers include α-olefins such as ethylene or propylene, other vinyl monomers such as vinyl acetate and vinyl stearate, and acrylic monomers such as methyl acrylate and 2-ethylhexyl acrylate. !
This invention can be used when using I-based monomers or vinylidene chloride and copolymerizing them with vinyl chloride. Furthermore, the present invention can also be used when vinyl chloride is graft-polymerized to ethylene vinyl acetate copolymer, ethylene propylene copolymer, or ethylene ethyl acrylate copolymer.

In this invention, as mentioned above, acrylic and derivatives are added to an aqueous medium to polymerize vinyl chloride in suspension, but the polymerization reaction process is not particularly different from conventional methods. . Moreover, the PvC obtained by the method of this invention does not differ from the conventional one in appearance.

In this invention, the PvC obtained as described above is roughly chlorinated. Chlorination can be carried out by various conventionally known methods. That is, there are known methods for chlorinating PvC in a gas phase or liquid phase, especially in an aqueous medium or an organic solvent, but the chlorination step in this invention can be carried out by any of these methods. good. In addition, the chlorination process can be carried out in the same way as before. ◇The CPVC obtained in this way has different chlorine contents depending on the degree of chlorination, but this invention method can reduce the amount of chlorine content. Of those that can be used, preferred are those having a chlorine content of 60 to 70% by weight.

The CPVC obtained by the method of this invention does not differ outwardly from conventional CPVC; however, the thermal stability of the CPVC obtained by this invention is considerably improved over conventional CPVC. That is, when CPVC is heated and melted, the resulting melt is less colored in the inventive melt than in the conventional one.

Less coloration of the melt would be of great benefit to CPVC. This is because less coloration means that the resin does not undergo unpleasant discoloration even when heated for long periods of time, which is an improvement on what was considered to be the biggest drawback of CPVC. . That is,
Until now, CPVC was not easy to mold because it was easily colored when heated, which had hindered its use in various fields, but once improvements were made to reduce this coloring, CPVC became beautiful. This is because it becomes possible to easily produce colored or colorless and transparent molded bodies, opening up new uses in various fields. Therefore, it can be said that the method of this invention brings about remarkable effects in this respect. In particular, when the CPVC obtained by the method of this invention is added with a sulfur-containing dialkyltin compound, the thermal stability between - The browning time and blackening time are increased.

EXAMPLES Below, the present invention will be explained in detail with reference to Examples and Comparative Examples, and the remarkable effects of the present invention will be illustrated by examples. In the following, parts simply mean parts by weight.

Example 1 Put 170 parts of ion-exchanged water into a stainless steel autoclave, and add polyacrylic acid (average degree of polymerization: 5000) to this water.
) and 0.1 part of hydroxypropyl methylcellulose (Metrose 90SH-1 manufactured by Shin-Etsu Chemical Co., Ltd.) as a dispersant.
After processing 0.1 part of 00) and adding 0.08 part of t-butyl peroxypivalate as a polymerization catalyst and stirring well, the air in the autoclave was removed by vacuum suction. Thereafter, 100 parts of vinyl chloride monomer was pressurized into the autoclave, and the temperature was raised to 68°C while stirring.
Suspension polymerization was carried out at this temperature. When 65 parts of the 100 parts of vinyl chloride monomer were polymerized and converted to PvC, the reaction was stopped and the remaining vinyl chloride monomer was removed.
The obtained solid resin was filtered to obtain PVC.

This PVC was placed in a glass-lined reactor, and ion-exchanged water was added to give a PvC to water ratio of 1:5. After replacing the inside of the reactor with nitrogen gas, chlorine gas was introduced into the container, and ultraviolet rays were irradiated at 50° C. to perform a chlorination reaction. After 8 hours of chlorination reaction, the degree of chlorination was 65%.
of CPVC was obtained. After replacing the chlorine gas remaining in the container with nitrogen gas, the by-produced hydrochloric acid was removed and dried to obtain CPVC.

To this cpvcl 0os, 2 parts of dioctyltin mercapto 7sef-) (manufactured by Nitto Kasei Co., Ltd. TVS #8831),
Acrylic processing aid (Mitsubishi Rayon Co., Ltd. Metaprene P
-551), 1.0 part of low-molecular polyethylene (Highwax 4202E manufactured by Mitsui Petrochemicals Co., Ltd.), and 5 parts of a reinforcing agent (Kureha BTAIN manufactured by Ou Chemical Co., Ltd.) were added. A roll sheet was obtained by mixing for a minute.

This rolled sheet was cut, laminated and pressed at 180° C. for 10 minutes to obtain a pressed plate. This pressed plate was almost colorless and transparent. Regarding this pressed plate, the color difference ΔE and the yellowness difference ΔN from the standard plate were measured using a 0 color difference meter manufactured by Nippon Denshoku Kogyo Co., Ltd. The results showed that ΔE was 46 and ΔN was 59, indicating that there was little coloring and good thermal stability.

Example 2 Example 1 except that 0.1 part of polymethacrylic acid (average degree of polymerization 7000) was used instead of polyacrylic acid.
PvC was obtained in exactly the same manner. Furthermore, CPVC was obtained using this PVC in exactly the same manner as in Example 1. This cpvc
A pressed plate was obtained in exactly the same manner as in Example 1. This press plate was colorless and transparent, had a ΔE of 44 and a ΔN of 58, and was found to have little coloration and good thermal stability.

Comparative Example 1 PVC was obtained in exactly the same manner as in Example 1, except that polyacrylic acid was not used and the amount of hydroxypropyl methyl cellulose was increased to 15 parts, and PvC was further added. After chlorination, CPVC was obtained. This CPVC was treated in exactly the same manner as in Example 1 to obtain a pressed plate. This press plate was already slightly colored yellow, and had a ΔE of 48 and a ΔN of 74.

Comparative Example 2 Example 1 except that the amount of polyacrylic acid used was increased to 0.15 parts and 0.15 parts of turubitan monostearate was used instead of hydroxypropyl methyl cellulose. In exactly the same way as 1, P
vC, CPVC, and a press plate were obtained. This press plate was slightly colored and had a ΔE of 56 and a ΔN of 79.

Comparative Example 8 In Example 1, polyvinyl alcohol (saponification degree 72%) was used instead of hydroxypropyl methylcellulose.
PVC was obtained in exactly the same manner as in Example 1, except that CPVC was used, and CPVC was obtained from this, and a press plate was further obtained. This press plate is colored and has a ΔE of 58 and a Δ
N was 88.

Claims (1)

[Claims] Vinyl chloride is dispersed in an aqueous medium, a water-soluble cellulose derivative is added together with polyacrylic acid, polymethacrylic acid, or a copolymer of acrylic acid and methacrylic acid to the aqueous medium, and the mixture is heated in the presence of an oil-soluble polymerization catalyst. A method for producing a chlorinated vinyl chloride resin, which comprises polymerizing vinyl chloride and chlorinating the vinyl chloride resin thus obtained.