JP2000281720A - Chlorinated vinyl chloride resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chlorinated vinyl chloride resin that has good thermal stability and especially, has less initial coloration. SOLUTION: A chlorinated vinyl chloride resin is produced by chlorinating a vinyl chloride resin wherein an ultraviolet and visible light absorbance and absorption value in a tetrahydrofuran solution containing 20 wt.% chlorinated vinyl chloride resin at 220 nm is not more than 0.4 in the case of the chlorinated vinyl chloride resin having a chlorine content in the range of not less than 60 wt.% to not more than 72 wt.% or wherein, in the case of the chlorinated vinyl chloride resin having a chlorine content in the range of not less than 63 wt.% to not more than 72 wt.%, a value of (an ultraviolet and visible absorbance and absorption value in the case of the chlorinated vinyl chloride resin having a chlorine content in the above-described range-0.4)/ (a chlorine content of the chlorinated vinyl chloride resin)-63.0} is in excess of 0 and is not more than 0.1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chlorinated vinyl chloride resin having excellent thermal stability and, in particular, little initial coloring.

[0002]

2. Description of the Related Art Chlorinated vinyl chloride resin (hereinafter referred to as CPV)
C) is generally a vinyl chloride resin (hereinafter referred to as PVC).
Chlorination). CPVC is expected to be used in a wide range of applications because it retains the advantages of PVC, such as flame retardancy and chemical resistance, and has the improved disadvantages of PVC, which is low in heat resistance. PVC has a major drawback in that it cannot be used at temperatures above 60-70 ° C because of its low heat distortion temperature, whereas CPVC has a heat-deformation temperature 20-40 ° C higher than PVC, which is a drawback of PVC. Heat resistance has been improved.

[0003] As described above, CPVC has a high heat distortion temperature. Therefore, when molding the CPVC, it must be heated to a high temperature and melted. However, C
Since PVC tends to be decomposed and colored when heated, the obtained CPVC molded product is colored, which makes it difficult to use it particularly for transparent applications and light-colored molded products.
Further, if the molding is performed at a relatively low temperature in order to suppress the coloring of the obtained CPVC molded article, the molded article is formed without being sufficiently gelled, so that the impact strength of the obtained CPVC molded article is deteriorated. The result will be. For these reasons, CPVC is used for a limited number of purposes, and has better thermal stability and less coloring during molding.
PVC is required.

[0004]

SUMMARY OF THE INVENTION The present invention provides a CPVC having good thermal stability and, in particular, little initial coloring.

[0005]

SUMMARY OF THE INVENTION The present invention considers that the initial coloration of a molded CPVC is due to thermal decomposition that originates from an irregular structure created during the chlorination reaction of the CPVC, When investigating the irregular structure and the initial coloration existing in the molecular structure of CPVC, the concentration of the molecular structure having an absorption at around 220 nm in an ultraviolet-visible absorptiometer (hereinafter, referred to as a UV meter), C
It has been found that there is a correlation between the initial coloring degree when PVC is molded. That is, the smaller the absorption around 220 nm (hereinafter referred to as UV absorption) in the UV meter, the lower the CPV
It was found that the degree of coloring (YI value) when C was molded was low, and the present invention was completed.

[0006] The first aspect of the present invention is a CPVC obtained by chlorinating PVC, wherein 220 wt% of a tetrahydrofuran (hereinafter referred to as THF) solution of 20% by weight of the CPVC is used.
m is 0.4 or less in CPVC having a chlorine content of 60% by weight or more and 72% by weight or less, or a chlorine content of 63% or less.
In a CPVC of not less than 72% by weight and not more than 72% by weight, the value of (UV absorption value of chlorine content in formula -0.4) / {(chlorine content of CPVC) -63.0} is more than 0 to 0.1. It is characterized by the following.

A second aspect of the present invention is characterized in that the CPVC according to the first aspect is chlorinated by ultraviolet irradiation.

A third aspect of the present invention is characterized in that the CPVC of the first aspect is chlorinated under heating and pressurization.

In a CPVC having a chlorine content of 60% by weight or more and 72% by weight or less, the UV absorption value is limited to 0.4 or less. It is necessary to keep it at 0.4 or less in order to obtain a CPVC with good initial coloring. Further, among them, in CPVC having a chlorine content of 63% by weight or more and 72% by weight or less, it is naturally effective to suppress UV absorption as much as possible to prevent the deterioration of initial coloring, but coloring is generally a problem. In order for the initial coloring to be at a level that can be used for molded products such as sheets and plates, the UV content for the chlorine content wt%
Absorption value is (UV absorption value of chlorine content in formula -0.4)
/ {(Chlorine content of CPVC) −63.0} is limited to more than 0 and not more than 0.1 (within the hatched region in FIG. 1).

[0010] CPVC is produced by chlorinating PVC as a raw material, but the PVC used in the present invention is not particularly limited. That is, PVC is produced by various polymerization methods such as a suspension polymerization method, an emulsion polymerization method, a solution polymerization method, and a bulk polymerization method, and any of them can be used as a raw material. Among them, those based on the suspension polymerization method are particularly preferred.

In the present invention, the method of chlorinating PVC is not particularly limited. For example, chlorination may be performed in any of a suspended state, a solution state, and a solid state. At this time, chlorination can be promoted by heating, irradiating ultraviolet rays, or adding a peroxide as a catalyst.

If the chlorine content of the above-mentioned CPVC is too low, the heat resistance becomes insufficient, and if it is too high, the moldability decreases.
0 wt% or more and 72 wt% or less.

In particular, in order to obtain a CPVC having a low UV absorption value and a good initial coloring, for example, an oxygen content of 10 to 10 is preferred.
Using 100 ppm of chlorine, a method of chlorinating at a reaction temperature of 110 to 135 ° C. or removing oxygen in a reaction vessel, introducing chlorine, and adding 5 to 50 ppm of hydrogen peroxide in a reaction process, There is a method of chlorination at a temperature of 100 to 140 ° C., and the like.

In particular, a method is preferred in which the oxygen concentration in the reaction vessel is as low as possible and the chlorination is carried out at a high temperature of 100 to 140 ° C. without irradiation with ultraviolet rays. In addition, even in the chlorination reaction method of irradiating ultraviolet rays, it is preferable to end the reaction in a relatively short time, or to minimize the amount of oxygen and oxygen dissolved in chlorine in the reaction vessel. It is effective in lowering the UV absorption value.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to examples, but the present invention is not limited to only these examples.

(Example 1) The inner volume that can be sealed is 300 m
1 container of 50 kg of raw material PVC and 175 k of deionized water
g, and after sufficiently stirring, the internal pressure is
The internal air is sucked until the pressure becomes 0.07 MPa, and then nitrogen gas is injected thereinto.
After sucking to 0.07MPa and removing oxygen, 10p
Internal pressure of 0.4MPa chlorine gas containing pm oxygen
And a chlorination reaction was performed at a temperature of 110 ° C. From 1 hour after the start of the introduction of chlorine to 30 minutes before the end of the chlorination reaction, a fixed amount of 100 ppm aqueous hydrogen peroxide was continuously added to accelerate the chlorination reaction. However, the amount and rate of hydrogen peroxide were adjusted so that the concentration became 10 ppm with respect to the raw material PVC. After performing a chlorination reaction until the target chlorine content was reached, the generated hydrochloric acid and residual chlorine were removed, followed by dehydration and drying to obtain the target CPVC. UV absorption was measured by the following method using the obtained CPVC, and molded under the following mixing conditions.
The I value was measured.

(Examples 2 to 7, Comparative Examples 1 to 7) Example 1
The reaction was carried out under the same conditions as the chlorination reaction method shown in
At this time, the oxygen concentration in the chlorine gas used and the reaction temperature were changed to prepare CPVC having different UV absorption values. UV absorption was measured by the following method using the obtained CPVC,
Molding was performed under the following mixing conditions, and the YI value was measured.

(UV measurement method) 10 g of 2 g of CPVC
Weigh accurately into a volumetric flask, add THF and add CPV
After dissolving C, THF is further added up to the marked line. This solution was put into a quartz cell for UV measurement, and was made by Hitachi (U-3).
300) The sample was set on a UV measuring instrument, and the absorbance at 220 nm was measured.

(Initial coloring) 100 parts by weight of CPVC, 2.0 parts by weight of a malate tin-based stabilizer, 0.5 parts by weight of a processing aid,
100 g of the compound comprising 10 parts by weight of MBS was kneaded with a 6-inch variable speed roll at a roll temperature of 200 ° C. for 3 minutes to prepare a roll sheet. This roll sheet was press-formed at a temperature of 200 ° C. under the conditions of preheating for 4 minutes and pressurization (150 kg / cm ² ) for 5 minutes, and the yellowness (YI value) of the obtained pressed plate was obtained.
Was measured.

As the raw material PVC for CPVC used in the examples and comparative examples, PVC having an average degree of polymerization of 1000 obtained by suspension polymerization was used.

[0021]

[Table 1]

[0022]

The present invention provides a CPVC having a low initial coloring property and good heat stability at the time of molding by reducing the UV absorption value at 220 nm of the CPVC.

[Brief description of the drawings]

FIG. 1 shows the chlorine content (% by weight) and U of CPVC of the present invention.
5 is a graph showing a relationship with a V absorption value (in a hatched region).

Claims (3)

[Claims] 1. A chlorinated vinyl chloride resin obtained by chlorinating a vinyl chloride resin, wherein a 20% by weight solution of the chlorinated vinyl chloride resin in a tetrahydrofuran solution has an ultraviolet-visible absorption value at 220 nm and a chlorine content of 60% by weight
In a chlorinated vinyl chloride resin having a chlorine content of 63% by weight or more and 72% by weight or less in a chlorinated vinyl chloride resin having a chlorine content of UV-visible absorbance absorption value -0.4) /
｛(Chlorine content of chlorinated vinyl chloride resin) -63.
A chlorinated vinyl chloride resin wherein the value of 0 ° is more than 0 and 0.1 or less. 2. The chlorinated vinyl chloride resin according to claim 1, wherein the chlorinated vinyl chloride resin is chlorinated by ultraviolet irradiation. 3. The chlorinated vinyl chloride resin according to claim 1, which is chlorinated under heat and pressure.