JPH01217008A - Photochlorination of polyvinyl chloride-based resin - Google Patents

Abstract

PURPOSE:To obtain a chlorinated polyvinyl chloride-based resin with uniform distribution of chlorine content, good in fluidity in its thermal processing, little in heat discoloration, by reaction of chlorine with a polyvinyl chloride-based resin under photoirradiation of specified condition. CONSTITUTION:The objective chlorinated polyvinyl chloride-based resin can be obtained by reaction of chlorine with a polyvinyl chloride-based resin (pref. with an average granular size of 10-500mun and porosity of 0.05-0.5cc/g) under such conditions as to alternately repeating photoshielding and photoirradiation. A preferable process is as follows: said porous granular polyvinyl chloride-based resin is suspended in chlorine-dissolved water and passed through a tubular reactor so that the mean passing time for said suspension at one photoirradiation part in said reactor is 10<-6>-10sec. and the means residence time at one photo-shielding part 50-1,000sec.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for photochlorinating polyvinyl chloride resin (hereinafter abbreviated as PVC), and more specifically relates to a method for photochlorinating polyvinyl chloride resin (hereinafter abbreviated as PVC). The present invention relates to a method of carrying out a chlorination reaction of pvC using light when producing pvC (abbreviated as cpvC).

[Conventional technology and problems]

CPVC, which is obtained by chlorinating PVC, has high heat resistance and other excellent properties, and is therefore widely used industrially.

As an industrial method for chlorinating PvC, solid Pv
It is common to carry out a heterogeneous reaction in which C particles are brought into contact with chlorine in a gas phase or in water. It is also possible to swell the ToC particles by adding chloroform or the like, or to perform a chlorination reaction by dissolving PVC in a solvent such as dichloroethane. However, methods using swelling agents and solvents are not common industrially because they are difficult to separate and remove and a small amount remains. It has good dispersion and temperature control and easy light irradiation.

This chlorination reaction is performed under light irradiation conditions.

When performing light irradiation, there is a method in which multiple light sources are immersed in a stirred tank reactor (Japanese Patent Publication No. 43-5890), a method in which a light irradiation part is provided in the external circulation flow path and light is irradiated from the outside (Japanese Patent Publication No. 43-5890). 46-17128) are being recommended. As a light source, visible light or ultraviolet light is used, such as a mercury lamp, a tungsten lamp, or a fluorescent lamp. Also, l per second
- Method using a light source that pulsates with 120 pulses (Unexamined Japanese Patent Publication No. 5
9-58007) is also known.

PvC chlorinated by such a method has weather resistance,
It is a general-purpose resin with excellent flame resistance and chemical resistance, and its heat distortion temperature is 20-50 degrees higher than that of raw material PVC1.
Since it can be used at high temperatures of 00°C or higher, it has many applications including pipes such as hot water supply piping and electrical products.

Although CPVC conventionally produced by the method described above has some excellent properties, it has drawbacks in thermal stability and processability. CPVC has a high glass transition temperature, so when forming it into sheets or pipes, it must be processed at a higher temperature than PvC.
VC is molded by extrusion molding, calender roll, hot press, injection molding, etc. depending on the type of molded product, but in any case, the fluidity of the molten polymer during processing poses a problem. If the fluidity is poor, air bubbles may remain during kneading, or the kneading may be insufficient and the finished product may be poor. Therefore, when processed at high temperatures to improve fluidity, a problem arises in that thermal coloring occurs in CPVC molded products. Especially in injection molding, etc., which have strict conditions,
In the case of CPVC, which has poor thermal stability, the resin may burn.

This thermal coloration is believed to be caused by thermal decomposition at high temperatures.

It is thought that the problems with the thermal stability and processability of CPVC are largely related to the non-uniformity of the chlorine content, which will be described later.

In other words, the glass transition temperature of CPVC increases as the chlorination rate increases, but if the chlorine content is significantly nonuniform, the chlorine content is significantly higher than the average value, and the glass transition temperature increases. Because it contains components that reach high temperatures, the fluidity of the molten polymer during processing becomes poor, resulting in poor finished molded products, and in order to improve fluidity, the processing temperature must be raised. In this case, problems such as thermal coloring as described above occur. In addition, if the chlorine content is significantly uneven, unreacted PVC may remain in the cpvC, which may cause thermal deterioration such as dehydrochloric acid reaction during high-temperature processing, resulting in coloration of the molded product and a decrease in strength. causing problems such as

The non-uniformity of the chlorine content in CPVC is that when chlorine dissolves in PVC particles and reacts with them, it occurs more quickly in the outer part of the particle than in the center of the particle, and in small particles than in large particles. This is caused by being chlorinated. That is, since the diffusion rate of chlorine in the PVC resin phase is extremely low, less chlorine is supplied to the center of the particle than to the outer part of the particle, resulting in a non-uniform distribution of reaction rates.

On the other hand, cpvC chlorinated using a solvent or a swelling agent has a relatively uniform chlorine content. According to the observation results by NMR method regarding the bonding state of chlorine in CPVC, compared to CPVC by solution method, CPVC by water suspension method or gas phase method is
It has been reported that chlorine is unevenly distributed in c.

R, A, et at,: Macromole
cules, Vol. 18. No, 6+p, 1
257-1265 (1985)), this is thought to be due to the fact that the diffusion rate of chlorine is higher in the solution or swollen resin phase than in the solid resin phase.

When swelling with chloroform, do not use a swelling agent.c
It has been reported that compared to PVC, the thermal dehydrochlorination reaction rate is slower and the mechanical properties of molded products are superior (
Ajroldi, G, et al, H^dv.

Che+m, Scr,, N99. p, 119437
(1971)).

However, chlorinated CPVC using a solvent or swelling agent
It is not easy to separate and remove the solvent and swelling agent, and they remain in the CPVC of the product, which limits their use and is not preferred.

[Problem that the invention seeks to solve]

The present inventors focused on the points mentioned above, and discovered that chlorine is r'
The following points were clarified as a result of quantitative research on the rate of dissolution in VC particles and diffusion transport and the rate of consumption by photoreaction.

Diffusion of chlorine in the PVC resin phase is extremely slow;
Since the chemical reaction rate of chlorination by light irradiation of c is relatively high, reaction conditions such as the conventional method of immersing a number of light sources in a stirred tank reactor (Japanese Patent Publication No. 43-5890) are recommended. Below, diffusion of chlorine in the resin phase will dominate the overall rate. Therefore, the vicinity of the outer surface of the resin phase reacts quickly with dissolved chlorine, but the interior of the resin phase does not react quickly, and the chlorination reaction rate, that is, the chlorine content becomes non-uniform.

Based on these findings, the present inventors conducted intensive research on a method for producing CPVC that has a more uniform chlorine content and superior physical properties than conventional methods without using solvents or swelling agents, and as a result, the present invention was developed. Completed the invention.

[Means for solving problems]

That is, the present invention is directed to a method for photochlorinating PVC, which is characterized in that in producing CPVC by reacting PVC and chlorine under light irradiation, light blocking and light irradiation are alternately repeated. It is something.

According to this method, chlorine is dissolved in the resin phase while light is blocked to stop the chemical reaction, and then light is irradiated to cause the chlorine dissolved in the resin phase to react. The chlorination reaction rate can be made more uniform than in the case of irradiation. In this case, the amount of chlorine physically dissolved and retained in the polymer resin phase is significantly smaller than the amount of chlorine consumed in the chlorination reaction of PVC, so the operations of light blocking and light irradiation are repeated alternately. . By studying the principles of this operation, that is, understanding the chlorine dissolution into the polymer resin phase and the photochlorination rate, it is possible to select preferable conditions for the light blocking and light irradiation times in the present invention.

Among the conventional methods, the method of providing a light irradiation part in the external circulation flow path and irradiating light from the outside (Japanese Patent Publication No. 46-17128) is mainly aimed at improving the structure of the light irradiation device. The chlorination reaction brought about by the present invention is caused by supplying chlorine to dissolving and diffusing chlorine at the same time as the photoreaction, and not ensuring sufficient residence time for dissolving and diffusing chlorine in the light-blocking part. The effect of equalizing the rate cannot be obtained. Among the conventional methods, a method using a light source that pulsates at l-120 pulses per second (Japanese Patent Laid-Open No. 59-5800
In case 7), the light interruption time per pulse is short and the contribution to the dissolution and diffusion of chlorine is extremely small, so that the effect of uniformizing the chlorination reaction rate brought about by the present invention cannot be obtained.

The raw material resin that can be chlorinated according to the present invention is particulate PVC obtained by various known methods such as bulk polymerization, emulsion polymerization, and suspension polymerization. The raw material PvC has a composition such as a homopolymer of vinyl chloride or a copolymer with ethylene, and various degrees of polymerization can be used.As a light source for irradiating the reaction system, from ultraviolet to Light with wavelengths in the visible range can be used, such as a water lamp. The photochlorination reaction of the present invention can be applied to a gas phase method in which the raw material PVC is brought into contact with chlorine gas, and also to a water suspension method in which the raw material PVC is suspended in water in which chlorine is dissolved.

The most important feature of the present invention is that light blocking and light irradiation are alternately repeated for the reaction system. Specific methods for implementing this include a method of repeatedly turning the light source lamp on and off, a method of repeatedly moving the lamp using a filter or light shielding plate that blocks the light, a method of repeatedly moving the position of the lamp, a method of using a flow-through method, etc. There is a method in which resin particles are passed through an external circulation reactor and light is irradiated at one or more locations in the device.

According to the present invention, for example, the average particle diameter is 10 μm to 500 μm.
Porosity 0.05 cc/g ~0.5 cc/
When photochlorinating the PVC raw material (g) according to the present invention, it is preferable that the light irradiation time per time is 10-" seconds to 10 seconds.
If it is shorter than 6 seconds, the time required for excitation of radicals in the photochlorination reaction, which is said to proceed by a radical chain mechanism, will not be reached, and if it is longer than 10 seconds, it will be close to a state of continuous light irradiation, and the present invention The desired uniformity of the chlorination reaction rate cannot be achieved sufficiently, and in this case, the light blocking time per time is 50 seconds to 1000 seconds.
If the light blocking time per time is preferably seconds, the uniformity of the chlorination reaction rate will be insufficient, and if it is too long, time will be wasted and productivity will decrease.

In addition, the average particle diameter is 10 μm to 500 μm and the porosity is 0.
05cc/g to 0.5cc/g of raw material PVC is suspended in chlorine-dissolved water and passed through a tubular reactor, and a light irradiation part is provided in the flow path to perform photochlorination. ,
The light source lamp is kept on continuously, and the average i! It is preferable that the Il elapsed time is 10-h seconds to 10 seconds, and the average residence time at one light-blocking part is 50 seconds to 1000 seconds. The container is a tubular container through which a predetermined reaction is performed while a reaction fluid is passed through the container.

In addition, in the present invention, the average particle diameter is CoulLarEl
electronics, Inc.
uller-counter, modelTaz
Measured by J.

The porosity was measured by mercury intrusion method, and the measuring device was Mi
crometrics In5trusent, Co
PoreSizer 9300J manufactured by RP, Inc. was used.

An embodiment will be described in more detail regarding the case where the raw material PVC is suspended in chlorine water and photochlorinated in a tubular reactor.

There is a method in which the chlorination reaction is completed by repeating light blocking and light irradiation while the suspension of raw material PVC passes from the inlet to the outlet of the flow path of the tubular reactor, but there are other methods in which the flow path is closed. A loop is provided, and the a-liquid is continuously passed through the flow path.
There is also a way to circulate it.

In the latter case, a stirring tank can be provided in the middle of the circulation channel. In this case, multiple circulation F
Two channels can also be provided. For the circulation of the suspension, a method of forced circulation using a pump, a method of natural W1 ringing using the gas lift effect of chlorine bubbles, etc. can be used. It is preferable that the light irradiation part has a structure in which light is irradiated from an external light source through a light-transmitting material such as glass or quartz glass to the flow path excluding the stirring tank.There is a light shielding structure before and after the light irradiation part. provide a portion. Chlorine can be supplied to the circulation path section of the reactor or to the stirring tank, or can be supplied from multiple locations.

[Action/Effect]

The CP and VC manufactured by the present invention have a uniform chlorination reaction rate, that is, a distribution of chlorine content, compared to those manufactured by a continuous light irradiation method, and flow during thermal processing. It has desirable qualities such as good properties and little heat discoloration. These characteristics of CPVC are well expressed in the glass transition temperature range determined by differential scanning calorimetry (hereinafter referred to as DSC), as shown in Examples and Comparative Examples below. Chlorine content 65 manufactured by light irradiation method
The glass transition point of wtχ CPVC is from 110℃ to 170℃.
C., whereas the glass transition temperature of CPVC of the same chlorine content produced by the present invention is in a narrow range of 120.degree. C. to 130.degree. Also 1,
Comparing the thermal stability at around 180°C, the CPVC produced by the present invention has a slower dehydrochlorination reaction rate than the CPVC produced by continuous light irradiation. , TGA),
The CPVC produced by the present invention undergoes weight loss due to thermal decomposition at a higher temperature than that produced by continuous light irradiation.

〔Example〕

The present invention will be further explained by showing examples and comparative examples below, but the present invention is not limited by these in any way.

Example 1 Polymerization degree of 600 and average particle size of 1 obtained by suspension polymerization
PVC particles of 20 μm and a porosity of 0.1 cc/g were placed in the first
The sample was placed in a quartz glass sample dish (2) of the reaction apparatus shown in the figure and charged into a quartz glass reaction tube (1). Reaction tube (1
), chlorine gas was introduced from the chlorine supply port (7), and υF was discharged from the chlorine discharge port (8). Turn on the mercury lamp (6), and install a movable light shielding plate (5) between the mercury lamp (6) and the sample dish (2) in the reaction tube (1) to block the light for 200 seconds each time. Then, remove the light shielding plate (5) and place it on the sample (5).
A one-step operation was performed in which light was irradiated for seconds.

In this way, photochlorination of PvC was performed, kl: 14
The change in weight of the sample was automatically measured by detecting the elongation of the spring (3) suspending the plate (2) with a displacement detector (4).

When the weight of the sample became 1.25 times the weight of the charged PVC, the light irradiation and the flow of chlorine gas were stopped to terminate the reaction, and CPVC chlorinated in the gas phase was obtained.

Comparative Example 1 The same PVC particles as in Example 1 were chlorinated in the same manner as in Example 1, except that the light shielding plate (5) was not used. That is, CPVC was obtained by continuously irradiating the sample with the mercury lamp (6) without blocking the light.

Regarding the CPVC obtained by the methods of Example 1 and Comparative Example 1, DSC,...! : The effects of the present invention were evaluated by comparing thermal properties by TGA. In DSC, the sample is approximately 5 mg.
The temperature increase rate was set at 10° C./min. T.G.
In A, the sample was approximately 10 mg, and the heating rate was 5°C/v.
*Measured as in.

The DSC measurement results are shown in Figure 2. In FIG. 2, the results of the sample of Example 1 are shown by curve a, the results of the sample of Comparative Example 1 are shown by curve 2, and the results of raw material PVC for comparative explanation are shown by curve C. In the figure, as the temperature rises for each sample, the Haese line moves upward and the specific heat changes, and this allows the range of the glass transition point to be observed. Chlorinated Example 1 (curve a) and Comparative Example 1
The glass transition point of the sample (curve b) is the raw material pv
c < The temperature is higher than that of curve C).

Comparative example 1 (curve b), the glass transition temperature of test II was 1
The glass transition temperature of the sample of Example I (curve a) was 120°C.
It is observed in a relatively narrow range from 140℃ to 140℃. This is interpreted to indicate that the chlorination reaction rate of Sample i4 of Comparative Example 1 is widely distributed, whereas the chlorination reaction rate of the sample of Example 1 is relatively uniform. can.

The TGA measurement results for the samples of Example 1 and Comparative Example 1 are shown as curves d and e in FIG. 3, respectively. When all samples are heated to M temperature, thermal decomposition reactions such as dehydrochlorination occur, and the weight decreases to a constant weight again. Compared to the sample of Example 1 (curve d), this thermal decomposition reaction was
The sample of Comparative Example 1 (curve e) is observed from a lower temperature, and the temperature at which the weight decreases by half is 2 for the former (curve d).
97°C, whereas the latter (curve e) is 282°
It is C. From this, it can be seen that the sample of Example 1 is more stable in thermal processing etc. than the sample of Comparative Example 1.

Example 2 The same PVC particles as in Example 1 were charged into the stirring tank <A) of the apparatus shown in FIG. 4 and dispersed in water. After setting the temperature of this suspension to 50°C, chlorine supply to the stirring tank (A) was started, and a 20 cm long glass light irradiation section (D) provided in the external circulation channel (C) was heated. After lighting the high-pressure mercury lamp (J), open the flow path switching cock F, use the pump (B) to take out the suspension into the external Wi circulation path (C), and transfer the suspension to the external Wi circulation path (C).
It was allowed to flow at a linear velocity of /Sec. The suspension taken out from the stirring tank (A) and passed through the light irradiation part (D) was introduced into the fil↑ tank (E), and chlorine was supplied in a light-shielded state.

After discharging the suspension in the stirring tank (A), operate the flow path switching cocks (F, G, H, I) to transfer the suspension in the stirring tank (E) to the outside by the same operation as above. Circulation channel (C
), pass it through the light irradiation part (D), and put it in the stirring tank (
A) was introduced.

The chlorine content of CPVC, which can be measured by observing the amount of hydrochloric acid by-produced as a result of the chlorination reaction by repeating such flow path switching one after another, is 63-
When tχ was reached, the high pressure mercury lamp (J) was turned off to stop the reaction.

Comparative Example 2 PvC was photochlorinated using the same stirring tank as in Example 2. That is, the same PVC particles as in Example 1 were placed in a glass stirring tank, dispersed in water, and chlorine gas was supplied.

At this time, a high-pressure mercury lamp was installed immediately outside the stirring tank, and the PVC particle suspension was continuously irradiated with light through the glass wall of the stirring tank to effect a reaction. Chlorine content of cpvc is 63w
When tχ was reached, the high-pressure mercury lamp was turned off to stop the reaction.

The CPVC obtained by the method of Example 2 and Comparative Example 2 was subjected to DSC and TG in the same manner as in Example 1 and Comparative Example 1.
A was conducted to compare the thermal properties and evaluate the effects of the present invention.

According to the DSC measurement results, the glass transition temperature of the sample of Comparative Example 2 appears to range from 100°C to 160°C, but the glass transition temperature of the sample of Example 2 is 110°C.
It is observed in a relatively narrow range from 140℃ to 140℃. This can be interpreted to indicate that the chlorination reaction rate of the sample of Comparative Example 2 is widely distributed, whereas the chlorination reaction rate of the sample of Example 2 is relatively uniform. .

According to the TGA measurement results, the thermal decomposition reaction occurred in Example 2.
The sample of Comparative Example 2 is observed at a lower temperature than the sample of Example 2, and the temperature at which the weight decreases by half due to thermal decomposition reactions such as dehydrochlorination is 290°C for the sample of Example 2. The sample of Example 2 was at 280°C. From this,
It can be seen that the sample of Example 2 is more stable in thermal processing etc. than the sample of Comparative Example 2.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of the device used in Example 1, Figure 2 is the DS
C chart, FIG. 3 is a TGA chart, and FIG. 4 is a schematic diagram of the apparatus used in Example 2. In Fig. 1, 1: reaction tube, 2: sample plate, 3 spring, 4: displacement detector, 5: light shielding plate, 6: mercury lamp, 7: chlorine supply port, 8:
In Figure 4 of the chlorine outlet, A: PA stirring tank, B: pump, C: circulation flow path, D: light irradiation section, E: Pil, stirring tank, F: wave path switching cock, c: 'tin path switching cock. , H: Two channel switching cock, I: Channel switching cock, J
: Mercury lamp, K: Chlorine supply port, L: Chlorine discharge port, M: Light shielding plate Patent applicant Kanekabuchi Chemical Industry Co., Ltd.

Claims (1)

[Claims] 1. In producing a chlorinated polyvinyl chloride resin by reacting a polyvinyl chloride resin and chlorine under irradiation with light,
A method for photochlorinating polyvinyl chloride resin, which is characterized by alternately repeating light blocking and light irradiation. 2. Using porous particulate polyvinyl chloride resin with an average particle diameter of 10 μm to 500 μm and a porosity of 0.05 cc/g to 0.5 cc/g as a raw material, each light irradiation time was 10 The method according to claim 1, wherein the light interruption time is 6 seconds to 10 seconds, and the light interruption time per time is 50 seconds to 1000 seconds. 3. The method according to claim 1, wherein the polyvinyl chloride-based resin particles are suspended in water in which chlorine is dissolved and allowed to flow through a tubular reactor, and a light irradiation portion is provided in the flow path to carry out photochlorination. 4. Polyvinyl chloride resin in the form of porous particles with an average particle size of 10 μm to 500 μm and a porosity of 0.05 cc/g to 0.5 cc/g is suspended in chlorine-dissolved water and subjected to a tube reaction. The average passage time for the particle suspension to pass through one light-irradiated part of the reactor is 10^-^6
4. The method according to claim 3, wherein the average residence time at one light blocking portion is 50 seconds to 1000 seconds.