JPH054403B2 - - Google Patents

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
It is made by chlorinating PVC). CPVC is
It is expected to have a wide range of uses as it has the good properties of PVC and has improved the drawbacks of PVC. Specifically, like PVC, CPVC has excellent weather resistance, fire resistance, and chemical resistance. Moreover, PVC is
It has been said that it cannot be used at temperatures above 60-70℃ due to its low heat distortion temperature, and this has been considered a drawback.
CPVC has a heat distortion temperature 20-40°C higher than PVC, and was therefore evaluated as having improved heat resistance over PVC. Therefore, CPVC is about to have a wider range of uses than PVC.

However, conventional CPVC was not suitable for the new applications being developed. The reason for this is that when conventional CPVC was molded for such uses, the CPVC was already colored from yellow to brown at the beginning of heating, and could not become colorless and transparent. Specifically, the application is for things that require colorless transparency, such as electronic component cases and display boards, but when CPVC is heated to be molded, some of the CPVC already decomposes when it begins to melt. It was colored yellow 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 CPVC that does not exhibit initial coloration when heated and melted, and forms a colorless and transparent melt.

According to literature, Special Publication No. 43-18553 is
An improvement to the PVC chlorination process is proposed. According to the proposal, suspending PVC in an aqueous medium in the presence of a hydrochloromethylene compound and further chlorinating the PVC in the presence of an acrylic acid polymer improves the chlorination process. be. According to this proposal, it is possible to obtain CPVC that has no 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 it is easy to cause various troubles due to the swelling of PVC. Since the removal of the agent is required, the disadvantage is that the operation becomes complicated. Therefore, the inventor attempted to eliminate the initial coloring of CPVC using an even simpler method.

This inventor prevents the initial coloring of CPVC,
Extensive research was conducted on the method of making CPVC into a colorless and transparent melt. As a result, the above-mentioned special public
Among the acrylic acid polymers described in Publication No. 18553, specific ones, namely polyacrylic acid,
By selecting polymethacrylic acid or a copolymer of acrylic acid and methacrylic acid and adding it together with a water-soluble cellulose derivative to an aqueous medium during the suspension polymerization of vinyl chloride, the resulting When PVC is further chlorinated to become CPVC,
It was found that CPVC became stable to heat and produced a colorless and transparent melt without initial coloration upon heating. 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. Polymerize vinyl chloride in the presence of
The present invention relates to a method for producing a chlorinated vinyl chloride resin, which is characterized by chlorinating the vinyl chloride resin obtained in this way.

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. In addition, the PVC obtained in this way can be chlorinated.
It is also known to make CPVC. Therefore, this invention involves 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 to obtain CPVC. It can be said that there is a method.
Although it is natural that substances added to the aqueous medium during the polymerization process affect the properties of the polymer, it is not clear that the effect extends even after chlorination and improves the thermal stability of CPVC. , a completely unexpected effect.

Furthermore, polyacrylic acid, polymethacrylic acid, or a copolymer of acrylic acid and methacrylic acid (hereinafter collectively referred to as acrylic)
are all water-soluble, and water-soluble cellulose derivatives (hereinafter referred to as derivatives) are also selected and used, so even if such materials are added to an aqueous medium, the polymerization reaction or By washing with water, which is always performed after the chlorination reaction, all
It is thought that it will be removed from PVC or CPVC. Therefore, it is considered that adding acrylic or a derivative during polymerization is unlikely to help stabilize the chlorinated vinyl chloride resin. However, the fact is completely contrary to this, and it is quite surprising that adding acrylic and derivatives to the aqueous medium during suspension polymerization has the effect of thermally stabilizing CPVC.

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 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 acid in an organic solvent, adding a polymerization initiator thereto, and performing a common solution polymerization method. As the polymerization initiator, for example, benzoyl peroxide can be used. It is preferable to use acrylic having a molecular weight in the range of 5,000 to 600,000.

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 hydroxymethylcellulose, hydroxyethylcellulose, and hydroxypropylcellulose. In addition, carboxymethylcellulose and methylcellulose can also be used as the cellulose. All 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. That's because acrylics are not among what are generally considered dispersants. Also, since acrylic is not in the form of an ester or salt, but in the form of an acid itself, it is not thought that the acid form would aid in dispersion.

In this invention, the derivative is used in a ratio of 0.01 to 0.5 parts with respect to 100 parts by weight of the monomer to be polymerized,
Further, acrylic is used in a proportion of 0.01 to 0.5 parts. Among these, preferred is a range of 0.03 to 0.2 parts of the derivative and a range of 0.03 to 0.3 parts 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 100
It is usually used in an amount of 0.02 to 0.2 parts by weight.
These catalysts and methods of using them are all well known, and the present invention relates to the use of the catalysts.
We will use what is known as is.

Except for vinyl chloride, all of the materials used in the polymerization process of this invention are liquid or solid at room 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 the air inside the autoclave is removed by vacuum suction.
Thereafter, a predetermined amount of vinyl chloride is injected under pressure to initiate polymerization. Thereafter, the temperature inside the autoclave is raised while stirring well, and 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 olefins such as ethylene or propylene, other vinyl monomers such as vinyl acetate and vinyl stearate, and acrylic acid monomers such as methyl acrylate and 2-ethylhexyl acrylate. This invention can be used when copolymerizing vinylidene chloride with vinylidene chloride or vinylidene 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. . In addition, the PVC obtained by the method of this invention does not differ in appearance from conventional PVC.

In this invention, obtained as described above
Further chlorinate the PVC. Chlorination can be carried out by various conventionally known methods. That is, it is known that PVC can be chlorinated in a gas phase or a liquid phase, particularly in an aqueous medium or an organic solvent, but the chlorination process in this invention can be carried out by any of these methods. good. Further, the chlorination step can be carried out in the same manner as conventionally. The CPVC obtained in this way has different chlorine contents depending on the degree of chlorination.
Any of these can be used in the method of this invention. Among these, the preferred one is one with a chlorine content of 60 to 70.
% by weight.

The CPVC obtained by the method of this invention does not differ from conventional CPVC in appearance. 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 molten material according to the present invention than in the conventional CPVC.

Less coloration of the melt is a major benefit for CPVC. This is because less coloration means that the resin will not undergo unpleasant discoloration even when heated for long periods of time.
This is because it improves what was considered to be the biggest drawback of CPVC. That is, until now CPVC
CPVC is not easy to mold because it tends to discolor when heated, and this has hindered its use in various fields until now. However, once improvements were made to reduce this discoloration, CPVC could be colored beautifully. This is because colorless and transparent molded bodies can be easily produced, opening up new applications in various fields. Therefore, it can be said that the method of this invention brings about a remarkable effect in this respect.

In particular, CPVC obtained by the method of this invention
When a sulfur-containing dialkyltin compound is added to this, the thermal stability becomes even better and the browning time and blackening time are extended.

EXAMPLES Below, examples and comparative examples will be given to explain the details of this invention, and also to demonstrate the remarkable effects of this invention. In the following, parts simply mean parts by weight.

Example 1 Ion exchanged water in a stainless steel autoclave
To this water were added 0.1 part of polyacrylic acid (average degree of polymerization approximately 5000), 0.1 part of hydroxypropyl methyl cellulose (Metrose 90SH-100 manufactured by Shin-Etsu Chemical Co., Ltd.) as a dispersant, and t as a polymerization catalyst. After adding 0.03 part of -butyl peroxypivalate and stirring well, the air in the autoclave was removed by vacuum suction. Then, 100 parts of vinyl chloride monomer was press-fitted into the autoclave.
The temperature was raised to 68°C while stirring, and suspension polymerization was carried out at this temperature. Thus, when 65 parts of 100 parts of vinyl chloride monomer are polymerized and converted to PVC,
The reaction was stopped, residual vinyl chloride monomer was removed, and the resulting solid resin was filtered to obtain PVC.

Put this PVC into a glass-lined reactor,
Further, ion-exchanged water was added to make the PVC to water ratio 1:5. After purging the inside of the reactor with nitrogen gas, chlorine gas was introduced into the container, and a chlorination reaction was performed by irradiating it with ultraviolet rays at 50°C. As a result of carrying out the chlorination reaction for 8 hours, CPVC with a degree of chlorination of 65% was obtained. After replacing the chlorine gas remaining in the container with nitrogen gas, remove the by-product hydrochloric acid and dry it.
Got CPVC.

To 100 parts of this CPVC, 2 parts of dioctyltin mercaptoacetate (manufactured by Nitto Kasei Co., Ltd. TVS #8831),
Adding 1.5 parts of acrylic processing aid (Metablen P-551 manufactured by Mitsubishi Rayon Co., Ltd.), 1.0 part of low molecular weight polyethylene (Hiwatux 4202E manufactured by Mitsui Petrochemicals Co., Ltd.), and 5 parts of a reinforcing agent (Kureha BTAN manufactured by Kureha Chemical Co., Ltd.), a 6-inch Using a roll, the mixture was kneaded at 180°C for 5 minutes to obtain a rolled sheet. This rolled sheet was cut, laminated and pressed at 180℃ for 10 minutes.
A pressed plate was obtained. 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 color difference meter manufactured by Nippon Denshoku Kogyo Co., Ltd. The result is △E is 46, △N
was 59, indicating that there was little coloring and good thermal stability.

Example 2 PVC was obtained in exactly the same manner as in Example 1, except that 0.1 part of polymethacrylic acid (average degree of polymerization of about 7000) was used instead of polyacrylic acid. Further, this PVC was treated in exactly the same manner as in Example 1 to obtain CPVC. A pressed plate was obtained from this CPVC in exactly the same manner as in Example 1. This press plate is colorless and transparent,
ΔE was 44 and ΔN was 58, indicating that there was little coloring 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 methylcellulose was increased to 1.5 parts, and PVC was further added. CPVC was obtained by chlorination. This CPVC was treated in exactly the same manner as in Example 1 to obtain a pressed plate. This press board is already slightly colored yellow, △E
was 48, and △N was 74.

Comparative Example 2 The same procedure as in Example 1 was carried out except that the amount of polyacrylic acid used was increased to 0.15 parts and 0.15 parts of sorbitan monostearate was used instead of hydroxypropyl methyl cellulose. I got PVC, CPVC, and even prels board. This press plate was slightly colored and had a ΔE of 56 and a ΔN of 79.

Comparative Example 3 PVC was obtained in exactly the same manner as in Example 1, except that polyvinyl alcohol (saponification degree 72%) was used instead of hydroxypropyl methylcellulose.
CPVC was obtained, and a pressed plate was also obtained. This press plate was colored and had a ΔE of 58 and a ΔN of 83.

Claims (1)

[Claims] 1 Disperse vinyl chloride in an aqueous medium, and add polyacrylic acid, polymethacrylic acid, or a copolymer of acrylic acid and methacrylic acid to the aqueous medium,
A method for producing a chlorinated vinyl chloride resin, which comprises adding a water-soluble cellulose derivative, polymerizing vinyl chloride in the presence of an oil-soluble polymerization catalyst, and chlorinating the vinyl chloride resin thus obtained.