JPH10168122A - Production of chlorinated vinyl chloride resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject resin excellent in initial coloration resistance and thermal stability on the thermal molding treatment of the resin in good productivity by blowing chlorine gas small in an oxygen concentration into the aqueous suspension of a vinyl chloride resin, irradiating the suspension with a mercury lamp, and continuously removing the chlorine gas from the reactor during the chlorination reaction. SOLUTION: This method for producing a chlorinated vinyl chloride resin comprises suspending a vinyl chloride resin in an aqueous medium, blowing chlorine gas having an oxygen concentration of <=1000ppm, preferably <=200ppm, into the suspension, simultaneously irradiating the suspension with a mercury lamp, and removing the chloride gas in an amount of at least 0.005 time wt., preferably 0.01-5 time wt., that of the vinyl chloride resin from the reactor during the chlorination reaction, thus obtaining the objective resin having a chlorination degree of 60-73wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a chlorinated vinyl chloride resin, and more particularly, to a chlorinated vinyl chloride having high productivity and improved initial coloring property and thermal stability during heat molding. The present invention relates to a method for producing a resin.

[0002]

2. Description of the Related Art Chlorinated vinyl chloride resin (hereinafter referred to as CPV)
C) is produced by chlorinating a vinyl chloride resin (hereinafter referred to as PVC). CPVC is an improvement of the properties of PVC, while retaining the properties that are said to be the advantages of PVC. That is, CPVC retains the excellent weather resistance, fire resistance and chemical resistance of PVC. On the other hand, PVC has a drawback in that it has a low heat distortion temperature and cannot be used for hot water.
Has an advantage that its heat distortion temperature is higher than that of PVC by 20 to 40 ° C. and can be used for hot water. Therefore,
CPVC can be widely used in fields such as heat-resistant pipes, heat-resistant joints, heat-resistant valves, and heat-resistant industrial boards.

[0003] As described above, CPVC has a high heat distortion temperature. Therefore, in order to process and mold CPVC,
It must be heated and melted at a higher temperature than PVC.
However, CPVC has poor thermal stability, and has the disadvantage of decomposing and coloring when heated. Therefore, CPVC is inferior in initial coloring property in molding by heating to PVC.
In addition, there is a drawback that burning tends to occur during molding and processing, and the width of molding and processing is narrow. Therefore, a method for improving the initial coloring property and thermal stability of CPVC is desired.

Further, in a general method for producing CPVC in which PVC is blown with chlorine gas in an aqueous suspension and chlorinated under irradiation with a mercury lamp, the chlorination reaction time is long and productivity is poor. Therefore, in order to improve the productivity of CPVC,
There is a need for a production method that reduces the chlorination reaction time.

[0005] CPVC with excellent initial coloring and thermal stability
Have been proposed previously. For example, Japanese Patent Application Laid-Open No. 3-166205 proposes a method for producing CPVC by chlorinating PVC using a specific dispersing agent. Not. Further, the CPVC obtained by this method is not necessarily satisfactory in the improvement of the initial coloring property and the thermal stability.

Japanese Patent Application Laid-Open No. 4-198349 discloses that a composition obtained by blending a specific compounding agent with CPVC has a
Although it has been proposed to improve the initial colorability and thermal stability of VC, this method requires the use of a specific compounding agent and is not easy to implement. Further, the improvement of the initial coloring property and the thermal stability of the CPVC obtained by this method is not necessarily sufficient.

On the other hand, in the production method of CPVC, a method of increasing the productivity by shortening the chlorination reaction time has not yet been proposed.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing CPVC having good initial coloring property and thermal stability. Still further, the present invention provides a method for producing CPVC with high productivity by shortening the chlorination reaction time.

[0009]

Means for Solving the Problems The present inventors suspend PVC in an aqueous medium, blow chlorine gas into the suspension and irradiate it with a mercury lamp to chlorinate PVC to chlorinate it. In a method of producing 60 to 73% by weight of CPVC, the present inventors have conducted intensive studies with a particular focus on the oxygen concentration in chlorine gas. As a result, while controlling the oxygen concentration in chlorine gas used in the reaction, It has been found that by removing the chlorine gas, the initial coloring property and the thermal stability are improved, the chlorination reaction time is shortened, and the productivity is improved, and the present invention has been completed.

That is, in the present invention, PVC is suspended in an aqueous medium, chlorine gas is blown into the suspension and irradiated with a mercury lamp to chlorinate PVC to obtain a CPVC having a chlorination degree of 60 to 73% by weight. A chlorine gas having an oxygen concentration of 1000 ppm or less, and removing chlorine gas in the reactor at least 0.005 times the weight of PVC during chlorination. The contents are as follows.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION PVC in the present invention is a polymerization of a vinyl chloride monomer. As vinyl chloride monomers,
In addition to the vinyl chloride monomer, other monomers copolymerizable with the vinyl chloride monomer are included. The other monomers that can be copolymerized with the vinyl chloride monomer include monomers such as ethylene, propylene, vinyl acetate, allyl chloride, allyl glycidyl ether, acrylate, methacrylate, and vinyl ether. Are used alone or in combination of two or more kinds, and the amount of use is about 0 to 20 parts by weight per 100 parts by weight of the vinyl chloride monomer.

The method for producing PVC used as a raw material is not limited at all. That is, the PVC used may be one produced by any of a suspension polymerization method, an emulsion polymerization method, a solution polymerization method, and a bulk polymerization method. Furthermore, in the suspension polymerization method, there is no limitation on the dispersant used.

Although the average degree of polymerization of PVC is not limited, the average degree of polymerization is 400 to 200 because the obtained CPVC is used for pipes, joints, valves, industrial plates, sheets and the like.
0 is preferred. If the average degree of polymerization is less than 400, the impact strength of the CPVC molded article is low, and if it exceeds 2,000, the melt viscosity of the CPVC tends to be high, making it difficult to process.

As the aqueous medium for suspending PVC, deionized water or distilled water may be used. P
After charging the VC and the aqueous medium into the reactor, or while charging, stirring with a stirrer to disperse the PVC in water,
Suspend C in water.

[0015] The resulting suspension may be sucked into the reactor using a vacuum pump and degassed to remove oxygen. After degassing, nitrogen may be passed through the reactor to further remove oxygen, and then the inside of the reactor may be sucked again by a vacuum pump to degas.

Next, chlorine gas having an oxygen concentration of 1000 ppm or less is blown into the reactor. Oxygen concentration in chlorine gas is 1
The method of reducing the concentration to 000 ppm or less is not particularly limited, but a simple method is to liquefy chlorine gas obtained by electrolysis of a saline solution to reduce the oxygen concentration to 1000 ppm or less excluding most of oxygen. In order to further enhance the effects of the present invention, it is desirable that the oxygen concentration in the chlorine gas be 200 ppm or less.
The method for reducing the oxygen concentration in the chlorine gas to 200 ppm or less is not particularly limited, but it can be easily obtained by liquefying the chlorine gas obtained by electrolysis of the saline at a liquefaction rate of 97% or less.
If the oxygen concentration in the chlorine gas exceeds 1000 ppm, the intended effects of the present invention cannot be achieved. There is no particular lower limit.

Simultaneously with or after blowing chlorine gas into the reactor, the suspension is irradiated with a high-pressure mercury lamp to chlorinate PVC. P due to ultraviolet light emitted from a high-pressure mercury lamp
The photochlorination of VC is not a special matter.
8-103507 and JP-A-64-6002. In the present invention, chlorine gas in the reactor is removed during chlorination of PVC. The removal of the chlorine gas may be performed once or intermittently during the chlorination reaction,
In order to further enhance the effect of the present invention, it is preferable to carry out continuously.

The amount of chlorine gas to be removed must be at least 0.005 times the weight of PVC, and is preferably 0.01 to 5 times.
5 times the amount. The amount of chlorine gas removed is 0.1% of the weight of PVC.
If the amount is less than 005 times, the intended effect of the present invention cannot be sufficiently obtained. On the other hand, when the amount exceeds 5 times, the treatment of the removed chlorine gas requires a large amount of equipment cost and operation cost, which is not preferable.

The chlorine gas may be removed by any method. For example, an orifice may be provided in a pipe above the reactor, and the chlorine gas may be removed therefrom. The removed chlorine gas may be returned to the chlorine gas line of the salt water electrolysis plant, or may be returned to the chlorine gas line of a facility for liquefying chlorine gas.

The pressure in the reactor during the chlorination reaction is from 0 to 1
It is preferably kg / cm ² gauge pressure. Reaction pressure is 0
If the pressure is less than kg / cm ² gauge, it is difficult to remove chlorine gas from the reactor of the present invention. If the pressure is more than 1 kg / cm ² gauge, the reactor and the mercury lamp need to have pressure resistance,
Not only is the equipment cost expensive, but also the operation is complicated, which is not preferable.

Furthermore, the pressure in the reactor is preferably substantially constant during the chlorination reaction. This means that if the pressure in the reactor fluctuates, the balance between the supply, consumption and removal of chlorine gas in the reactor fluctuates, making operation difficult and
This is because the desired effect of the present invention is reduced.

The temperature in the reactor during the chlorination reaction is not particularly limited, but, for example, the reaction starting temperature is 50 ° C. or less,
The temperature reaching the latter stage of the reaction is preferably 50 to 90 ° C. If the reaction temperature is too low, the chlorination reaction time will be prolonged and the productivity will decrease. On the other hand, if the reaction temperature is too high, the initial coloring and thermal stability of the obtained CPVC will be unfavorably deteriorated.

The chlorination reaction was stopped by measuring the concentration of hydrogen chloride in the reaction solution in the reactor.
Is measured, and when the CPVC reaches a predetermined chlorination degree of 60 to 73% by weight, the irradiation of the mercury lamp is stopped to stop the chlorination reaction. At the same time, nitrogen gas was introduced into the reactor to expel chlorine gas dissolved in the reaction solution.
Washing and drying are performed to obtain CPVC powder.

[0024]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples, which do not limit the present invention in any way. In the following description, "part" or "%"
Unless otherwise specified, "parts by weight" or "% by weight" respectively
Represents Incidentally, the thermal stability test in Examples and Comparative Examples,
The method of measuring the color difference b value of the press plate is as follows.

(A) Thermal Stability Test A roll sheet piece cut to 50 × 40 mm was taken out every 10 to 15 minutes in a 195 ° C. gear oven, and the degree of blackening was visually observed. Time required for blackening (blackening time:
Minutes).

(B) Initial coloring property Color difference meter (Σ80 COLOR MEASU manufactured by Nippon Denshoku Industries Co., Ltd.)
RING SYSTEM), the b value (yellowness) of the pressed plate was measured.

Examples 1 to 14 and Comparative Examples 1 to 5 As PVC, an average degree of polymerization of 70 produced by a suspension polymerization method was used.
A powder with an average particle size of 160 microns at 0 was used. In a reactor, put 15 kg of the above PVC powder and 35 kg of deionized water,
After sufficiently stirring, the internal air was sucked by a vacuum pump, and the internal pressure was maintained at -0.6 kg / cm ² G for 10 minutes. Then
After further removing oxygen in the reactor through nitrogen gas,
Suction was again applied with a vacuum pump, and the above pressure was maintained for 10 minutes to remove oxygen in the reactor. Next, chlorine gas having various oxygen concentrations was supplied to the reactor, and the inside of the reactor was replaced with chlorine gas for 10 minutes, and then irradiated with a high-pressure mercury lamp to perform a chlorination reaction.

During the chlorination reaction, the internal pressure was adjusted with chlorine gas, and at the same time, chlorine gas was removed from the orifice installed in the piping above the reactor. As shown in Table 1, removal of chlorine gas was performed continuously, intermittently, or once. In Comparative Examples 4 and 5, chlorine gas was not removed. The reaction pressure was adjusted during the reaction and 0.2 kg as shown in Table 1.
/ Cm ² G, and between 0 and 0.2 kg / cm ² G. A predetermined amount of chlorine gas was removed by adjusting the hole diameter of the orifice.

The chlorination reaction temperature is 35 ° C. at the start of the reaction,
During the reaction, the reaction was carried out at 70 ° C in Examples 1 to 10 and Comparative Examples 1 to 4, and at 60 ° C in Examples 11 to 14 and Comparative Example 5. The degree of chlorination was calculated from the concentration of hydrogen chloride in the reactor, and when the chlorine content reached a predetermined amount, irradiation of the mercury lamp was stopped and supply of chlorine gas was stopped. At the same time, the reactor was cooled and the residual chlorine gas was removed with nitrogen gas to terminate the chlorination reaction. The obtained product was washed with deionized water, dried and dried to obtain a white powder of CPVC.

(Physical Properties Test of CPVC) Examples 1 to 14,
The following formulations were prepared using the CPVC obtained in Comparative Examples 1 to 5. CPVC 100 parts MBS (Kanebuchi Chemical Industry Co., Ltd. product name: Kaneace B31) 10 parts Tin-based stabilizer (octyltin-mercapto) 2 parts Stearic acid 1 part Paraffin wax 0.7 parts The mixture was kneaded with a roll at 190 ° C. for 3 minutes. The obtained roll sheet is 50 mm long,
It was cut to a width of 40 mm and subjected to a thermal stability test. Further, the roll sheets obtained separately were stacked and pressed at 195 ° C. to form a pressed plate having a thickness of 3 mm, and the b value (yellowness) was measured with a color difference meter. Table 1 shows the obtained results.

[0031]

[Table 1]

As is clear from Table 1, it can be seen that the CPVC obtained by the production method of the present invention has excellent initial coloring properties and thermal stability, a short chlorination reaction time, and high productivity.

[0033]

As described above, according to the present invention, the CPVC
In addition to improving the initial coloring property and thermal stability during heat molding, the reaction time to reach a predetermined chlorination degree is shortened,
Productivity is greatly increased.

Claims (6)

[Claims] 1. A vinyl chloride resin is suspended in an aqueous medium, chlorine gas is blown into the suspension, and a mercury lamp is irradiated thereon.
When chlorinating a vinyl chloride resin to produce a chlorinated vinyl chloride resin having a chlorination degree of 60 to 73% by weight, a chlorine gas having an oxygen concentration of 1000 ppm or less is used, and a chlorine gas in the reactor is used during the chlorination. A method for producing a chlorinated vinyl chloride resin, wherein chlorine gas is removed at least in an amount of 0.005 times the weight of the vinyl chloride resin. 2. The method according to claim 1, wherein chlorine gas having an oxygen concentration of 200 ppm or less is used. 3. The production method according to claim 1, wherein chlorine gas in the reactor is continuously removed. 4. The method according to claim 1, wherein the chlorine gas is removed in an amount of 0.01 to 5 times the weight of the vinyl chloride resin during the chlorination reaction.
4. The production method according to any one of 3. 5. The pressure in the reactor during the chlorination reaction is 0 to 1
The production method according to claim 1, wherein the pressure is kg / cm ² gauge pressure. 6. The method according to claim 5, wherein the pressure in the reactor during the chlorination reaction is substantially constant.