JPS61283604A - After-treatment of chlorinated vinyl chloride resin - Google Patents

Abstract

PURPOSE:To obtain the titled resin which is not colored even when molten by heating, by mixing chlorinated vinyl chloride resin in a state of suspension in an aqueous medium with ethylene-diamine tetraacetic acid and separating the chlorinated vinyl chloride resin. CONSTITUTION:A chlorinated vinyl chloride resin (CPVC) prepared by chlorinating a vinyl chloride resin is suspended in an aqueous medium and mixed with ethylenediamine-tetraacetic acid (EDTA) and CPVC is separated from the aqueous medium. The amount of EDTA added is preferably about 500-10ppm based on the total weight of the aqueous suspension. EDTA may be added at an arbitrary time so far as it is added to the aqueous suspension from which hydrogen chloride as a by-product has been removed. It is preferable that the mixture is agitated at a temperature of 50-70 deg.C for 30-120min after the addition of EDTA.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for post-treatment of chlorinated vinyl chloride resins.

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 has improved the disadvantages of PVC, so
It is expected to have a wide range of uses. In detail, CPVC is PVC
It has excellent weather resistance, fire resistance, and chemical resistance. On the other hand, Pvc has a low heat distortion temperature, so it is 60~
It has the disadvantage that it cannot be used when the temperature exceeds 70'O. However, the heat distortion temperature of CPVC is 20 to 40°C higher than that of PVC, and therefore it has improved heat resistance of PVC. Therefore, CPVC is about to have a wider range of uses than PVC.

However, conventional CPVCs are unsuitable for new uses. Because conventional cpv
The reason c is because when this was heated for molding, the color changed from yellow to brown at the beginning of heating, and it could not become colorless and transparent. To be more specific, the newly opened applications require colorless and transparent materials, such as electronic component cases and display boards, but CPVC is used for molding.
When heated and melted, CPVC was already colored yellow and could not become colorless and transparent. Therefore, in order to find new uses, it was necessary to create CPVC that does not exhibit initial coloring when heated and melted, producing a colorless and transparent melt. This inventor stabilized CPVC, I also tried to obtain CPVC without any coloring.

In the case of PVC, the addition of certain compounds called stabilizers stabilizes PvC and reduces discoloration when heated and melted. Even if such a stabilizer for PVC is added to CPVC, CPVC is rarely stabilized.
No stabilization of pvc is obtained.

Therefore, although it is generally said that PVC and CPV (,!:) have similar properties to each other, a similar relationship does not hold when it comes to stabilization, and therefore, the stabilization effect must be confirmed individually. It has been found.

The inventors have found that ethylenediaminetetraacetic acid exhibits a significant effect in stabilizing CPVC when a special method of use is followed. Ethylenediaminetetraacetic acid (hereinafter referred to as E
DTA) is known as a PvC stabilizer. However, it is not known that EDTA helps stabilize CPVC. Therefore, the use of EDTA as a stabilizer for CPVC is novel in itself. The inventors have found an advantageous use of EDTA, not only as a stabilizer for CPVC, i.e. when the CPVC is still in aqueous suspension immediately after it has been manufactured. It has been confirmed that the usage method of adding the compound to an aqueous medium, stirring it, and then separating the aqueous medium is simple and brings about a remarkable effect. This method of use is significantly different from the conventional method of using stabilizers, which involves simply adding resin powder in a dry state. This invention was made based on such confirmation.

This invention involves mixing CPVC produced by chlorinating PvC with EDTA in a suspended state in an aqueous medium.
The present invention relates to a method for post-treatment of CPVC, which is characterized by separating CPVC from an aqueous medium.

EDTA is CHt N(CHt C00H)t
It is a colorless crystalline powder having the molecular formula CHt-N(CHt-COOH), and is a compound that is extremely slightly soluble in water. Since EDTA has the property of forming extremely stable water-soluble chelate compounds with many metals such as calcium and magnesium, it has been widely used for the analysis, separation, and removal of metals. In addition, EDTA is Pv
Although it was also used as a stabilizer for CPVC, it was not known as a stabilizer for CPVC.

Although this invention uses EDTA, the use of cpv
This is done under the conditions that always occur during the production of c. The condition is that CPVC is suspended in an aqueous medium. Specifically, CPVC is produced by chlorinating PVC, but the chlorination is carried out in the liquid phase, and when the chlorination reaction is completed, excess chlorine and by-product hydrogen chloride are removed, and only then can CPVC be produced. Separated. In order to remove chlorine and by-product hydrogen chloride, it is necessary to wash CPVC with water, so that CPVC is necessarily suspended in an aqueous medium during the washing process. EDTA is this AlJ! The use of EDTA in the present invention is extremely easy since it is sufficient to add it to an aqueous medium in a cloudy state and mix it with CPVC.

There is no particular limit to the amount of EDTA added, but it is preferably about 500 to 10 ppm based on the overall view of the aqueous suspension. In addition, the timing of adding EDTA is not limited to the above-mentioned case. When PvC is chlorinated in a state of FIF in an aqueous medium, immediately after removing chlorine and hydrogen chloride in the suspended state. EDTA may be added to this. In short, EDTA may be added at any time as long as the aqueous suspension is obtained after removing by-product hydrogen chloride. There is also no particular limitation on the temperature after adding EDTA. Preferably, the temperature is 30-1 at a temperature of 50-7.1.
Stir for 20 minutes.

After adding EDTA and mixing well, it is sufficient to separate the CPVC from the aqueous medium. Separation can be facilitated by passing. The obtained CPVC is dried as necessary to form a product.

Whether CPVC gives a colorless and transparent molded product can be determined by measuring the length of time it takes to turn black when heated and melted, and the degree of coloration of the sheet obtained by heating and melting. can. In other words, it can be said that the longer it takes to blacken and the less the degree of coloration of the sheet, the more transparent and colorless the molded product will be. According to the method of this invention, the blackening time is improved to, for example, 100 minutes or more at 190° C., so it is considered that CPVC has been greatly improved. In addition, the degree of coloring is such that the difference ΔE from the standard white board is 50 or less, and the yellowness difference ΔN is 70 or less, so it can be said that the improvement has been significantly improved. With simple operations during the process of heating and melting, CPVC with less coloring can be produced.
can be easily obtained. In particular, since EDTA is a compound that is very slightly soluble in water, by adding and mixing EDTA into a suspension of CPVC in an aqueous medium, it is possible to uniformly and easily contact EDTA with CPVC.

EDTA is a compound that is extremely slightly soluble in water, so when CPVC is separated from an aqueous medium, it is thought that EDTA will be completely separated from CPVC along with the aqueous medium, but in reality, EDTA is This results in a sufficient effect on stabilizing CPVC. This means that
When EDTA is added to powdered CPVC, a stabilizing effect cannot be obtained unless a large amount of EDTA is used, but as in this invention, it is added in an aqueous suspension state and the aqueous medium is separated after mixing. The case seems all the more surprising due to the fact that a significant stabilizing effect can be obtained using only small amounts of EDTA. This is EDTAt in aqueous medium.
-CPVC,! This may be due to the fact that during contact, EDTA forms water-soluble complexes with heavy metal salts, thereby removing all of the heavy metal salts present in CPVC. In any case, the stabilization of CPVC by the method of this invention is remarkable.

Examples and comparative examples are given below to explain the details of the method of this invention and the reasons why the effects of the method of this invention are so obvious. In the following, parts simply mean parts by weight.

Example 1 In a jacketed glass-lined reactor, 100 parts of PVC with an average degree of polymerization of 700 and 500 parts of ion-exchanged water were mixed with 2 people, the contents were stirred, PvC was suspended in water, and nitrogen gas was blown into the reaction vessel. The oxygen in the vessel was replaced with nitrogen. Next, chlorine gas was pressurized into the reactor, and the PVC was chlorinated while being irradiated with ultraviolet rays at 50°C. In this way, the chlorination reaction was carried out for 8 hours with PVC suspended in an aqueous medium to obtain CPVC with a chlorine content of 65% by weight. After removing unreacted chlorine in this suspension by nitrogen gas replacement, 5 EDTA was added to the slurry from which hydrochloric acid was removed.
00 ppm was added thereto, and the mixture was stirred at 50° C. for 1 hour. Thereafter, this slurry was dried to obtain CPVC powder.

To 100 parts of the above cPVc, dioctyltin mercaptoacetate (TVS #8831 manufactured by Nitto Kasei Co., Ltd.) 2
1 part, 15 parts of acrylic processing aid (Metablen P-551 manufactured by Mitsubishi Rayon Co., Ltd.), 1 part of low molecular weight polyethylene (Hiwax 4202E manufactured by Mitsui Petrochemicals Co., Ltd.), and a reinforcing agent (Kureha BTA Seal N manufactured by Ou Chemical Co., Ltd.) ) and mixed, and this mixture was kneaded for 5 minutes at 180° C. using a 6-inch roll to obtain a roll sheet. This roll sea)
An aging test was conducted by placing the sheet in a gear open at t-190° C., and the blackening time until the sheet blackened was determined. Further, the rolled sheets were cut, laminated, and pressed at 180° C. for 10 minutes to obtain a pressed plate. This press plate was manufactured by Nippon Denshoku Kogyo (
Color difference ΔE and yellowness difference ΔN from a standard white board were measured using a color difference meter manufactured by Co., Ltd., to measure colorability. As a result, blackening time! 110 minutes, ΔE was 45, and ΔN was 67, indicating that it took a long time to blacken and that there was little coloring. Example 2 In Example 1, the amount of EDTA added was reduced. 300
A roll sheet and a press plate were obtained in exactly the same manner as in Example 1 except that the amount was changed to ppm. The n-pn blackening time 1 and colorability of the roll sheet and press plate were measured in exactly the same manner as in Example 1. The blackening time was 120 minutes, ΔE was 48, and ΔN was 65, indicating that the blackening time was long and the coloration was low.

Comparison f1 CPVC was obtained in exactly the same manner as in Example 1, except that EDTA was not used in Example 1.

Using this CPVC, roll sheets and press plates were obtained in exactly the same manner as in Example 1, and the blackening time and coloring properties were examined. The zero blackening time was 80 minutes, ΔE was 52, and ΔN was 7.
8, the blackening time was short and the colorability was large, making it difficult to form a colorless and transparent molded product.

Comparative Example 2 In the CPVC manufacturing process of Example 1, CPVC obtained without using EDTA was used (this is Comparative Example 1).
A roll sheet and a press plate were obtained in exactly the same manner as in Example 1, except that 500 ppm of EDTA was added to the powdered CPVC during the molding process. Using this mouthpiece and press plate, the blackening time and coloring properties were measured in exactly the same manner as in Example 1. The blackening time was 90 minutes, ΔE was 52, and ΔN was 71. Therefore, it was difficult to make a colorless and transparent molded product.

Claims (1)

[Claims] The method is characterized in that a chlorinated vinyl chloride resin produced by chlorinating a vinyl chloride resin is suspended in an aqueous medium and mixed with ethylenediaminetetraacetic acid, and then the chlorinated vinyl chloride is separated from the aqueous medium. A post-treatment method for chlorinated vinyl chloride resin.