JPH11349767A - Chlorinated vinyl chloride-based resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject vinyl chloride-based resin excellent in heat resistance and heat stability and having good thermoformability by chlorinating a mixture of two or more kinds of vinyl chloride-based resins having average polymerization degree within a specific range and different in average polymerization degree. SOLUTION: This vinyl chloride-based resin is obtained by chlorinating a mixture of two or more kinds of vinyl chloride-based resins (PVC) having <800, preferably >=450 and <750 average polymerization degree and different in average polymerization degree. PVC having >=400 and <800 average polymerization degree among PVCs used for mixing is used as the PVC and PVC are mixed so that the difference between the lowest average polymerization degree and the highest polymerization degree is 100-400 and PVC whose distribution curve of polymerization degree has >=2 peaks is preferably chlorinated. Average chlorine content of the resin is preferably 60-72 wt.%. When PVC is chlorinated, it is preferable that hydrogen peroxide in an amount of 5-100 ppm based on PVC is added to a reactor and chlorination reaction of the resin is preferably carried out at 90-140 deg.C.

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 heat resistance, good thermoformability and excellent thermal stability.

[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 retains flame-retardant and chemical-resistant properties, which are said to be advantages of PVC, and
C is expected to be used in a wide range of applications because it has improved the low heat resistance temperature which is said to be a disadvantage of C. On the other hand, PVC has a major drawback that it cannot be used at temperatures of 60 to 70 ° C. or higher because of its low heat deformation temperature. On the other hand, the heat deformation temperature of CPVC is higher by 20 to 40 ° C. than that of PVC, and the heat resistance, which is a drawback of PVC, is improved.

[0003] The heat resistance of CPVC increases as its chlorine content increases. However, as the chlorine content increases, the viscosity of CPVC at the time of melting increases, and the molding process becomes more difficult. In addition, ordinary CPVC has poor thermal qualitative properties and tends to undergo thermal degradation when heated to high temperatures, and is decomposed and colored. If molding is performed at a low temperature in order to reduce coloring, CPVC does not melt sufficiently, resulting in a molded article with insufficient gelation, so that physical properties are not sufficiently exhibited and appearance is poor. Will be. This tendency is stronger as the chlorine content of CPVC increases.

[0004] For this reason, CPVC is used for extruding, injection molding, calendar molding, press molding, and blow molding.
In a thermoforming method through a melting and plasticizing step, a material having an average chlorine content of less than 68% by weight is generally used. Although CPVC having an average chlorine content of 68% by weight or more has already been developed, it cannot be used for the thermoforming method for the above-mentioned reason, and is mostly limited to uses dissolved in a solvent.

CPV having an average chlorine content of 68% by weight or more
C has high heat resistance, but at the same time, has a high melt viscosity, and thermoforming requires molding at a high temperature of 210 ° C. or higher. However, when thermoforming is performed at a high temperature of 210 ° C. or more, there are problems in that the molded product is colored, decomposed or burnt.

Therefore, when molded at a relatively low temperature of 180 to 200 ° C., as in the case of CPVC having an average chlorine content of less than 68% by weight, the coloring is small and no burns are produced, but the molding is not sufficiently melted. As a result, the gelation is insufficient, and the physical properties of the molded article are deteriorated and the appearance of the molded article is deteriorated. For these reasons, the molding temperature of CPVC is limited, and its use range is narrowed.

[0007] As a method of obtaining a good molded product even when molding CPVC having a high chlorine content at a relatively low temperature, a method of adding a processing aid such as an acrylic resin has been attempted. In this case, there are problems such as a decrease in heat resistance, which is an important property of CPVC having a high chlorine content, and an increase in cost due to the use of an additive.

[0008] Therefore, in order to obtain a good molded product even when thermoforming at a relatively low temperature while maintaining high heat resistance, which is a major feature of CPVC, the melt viscosity with respect to the chlorine content is higher than that of conventional CPVC. Therefore, there has been a demand for a CPVC which has a low thermal stability and has good thermal stability which is less susceptible to thermal deterioration due to thermoforming.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has excellent properties of PVC.
While maintaining the excellent heat resistance of CPVC, its melt viscosity is lowered to improve processability, and furthermore, it is made to have better thermal stability than conventional CPVC. It is an object of the present invention to provide a CPVC capable of obtaining a good molded body with no deterioration in appearance and little coloring.

[0010]

According to the first aspect of the present invention, there is provided a CPVC obtained by chlorinating PVC.
C is a mixture of two or more types of PVC having different average polymerization degrees, each having an average polymerization degree of less than 800.

The invention according to claim 2 is a CPVC obtained by chlorinating PVC, wherein the average degree of polymerization of the PVC is 4%.
It is characterized in that a mixture of two or more kinds of PVCs having different average polymerization degrees is used so that it is 50 or more and less than 750.

The third aspect of the present invention is a CPVC obtained by chlorinating PVC, which has an average chlorine content of 60 to 7%.
2% by weight.

[0013] The invention according to claim 4 is a CPVC obtained by chlorinating PVC, wherein the average degree of polymerization of the PVC used for mixing is 400 or more and less than 800, and the maximum degree of average polymerization of each PVC is less than 400. The difference from the minimum is 100 ~
400.

[0014] According to a fifth aspect of the present invention, in the production of CPVC, PVC is used as a raw material in a chlorination process.
ppm of hydrogen peroxide was added to the reactor, and 90 to 14 ppm was added.
The chlorination reaction is performed at a temperature of 0 ° C.

[0015] The invention according to claim 5 provides the obtained CPV.
C is for thermoforming.

The present invention has found that the degree of polymerization distribution of the raw material PVC before chlorination affects the melt viscosity of CPVC after chlorination. That is, PV having a normal polymerization degree distribution
The average degree of polymerization is the same as that of CPVC obtained by chlorinating C, but a PVC obtained by mixing two or more PVCs having different average degrees of polymerization to broaden the degree of polymerization distribution is obtained by chlorinating PVC.
Found that the melt viscosity was reduced without lowering the heat resistance, and as a result, the moldability was improved and a good thermoformed product was obtained.

That is, the conventional CPVC raw materials usually include PVC having a polymerization degree distribution curve having only one peak.
Has been used. On the other hand, two or more PVCs having different average polymerization degrees are mixed, and among the PVCs used in this case,
CPVC obtained by chlorinating the mixture having a difference in average polymerization degree between the lowest average polymerization degree and the highest average polymerization degree being 100 to 400, the polymerization degree distribution curve Has a single peak and the same average degree of polymerization than the CPVC obtained by chlorinating PVC,
The melt viscosity at the time of thermoforming decreases, and as a result, thermoforming is facilitated, and the physical properties and appearance of the obtained molded body are improved.

In particular, of the PVC used for mixing, PVC having an average degree of polymerization of 400 or more and less than 800 is used, and the difference between the average degree of polymerization and the one having the highest degree of polymerization is different. PVC which is mixed so as to have a polymerization degree distribution curve having two or more peaks.
CPVC obtained by chlorinating is more favorable in thermoformability, and is more preferable.

The average degree of polymerization of the PVC used for mixing in the present invention is limited to 400 or more and less than 800. When PVC having an average degree of polymerization of less than 400 is used for mixing, the resulting CP
The drop in the impact resistance of VC becomes remarkably large, and when a PVC having an average degree of polymerization of 800 or more is used for mixing, the melt viscosity is remarkably increased. Is reduced, so that it is limited to the above range.

The raw material PVC for the CPVC of the present invention has an average polymerization degree of 450 or more and less than 750, so that the mixing P
It is preferable to adjust the average degree of polymerization of VC. If the average degree of polymerization is less than 450, adhesion to a mold during thermoforming is strong, and burrs and burns are liable to occur, and the appearance of the molded article tends to be poor. Large and unsuitable for practical use. When the average degree of polymerization is 750 or more, the melt viscosity is too high and is not suitable for calendering or injection molding, which greatly affects the melt viscosity during molding.

In the present invention, the polymerization degree distribution curve is 2
As a method for obtaining a wide distribution of CPVC having two or more peaks, two or more types of PVCs having different average polymerization degrees are used in advance.
Can be obtained by chlorinating a PVC mixed with, or by separately chlorinating two or more PVCs having different average degrees of polymerization and then mixing to obtain a CPVC. It may be.

In the present invention, the average chlorine content of CPVC is preferably from 60 to 72% by weight. Particularly in a high chlorination region having an average chlorine content of 67% by weight or more, the effect of reducing the melt viscosity and improving the thermoformability is great. CPVC having an average chlorine content of less than 60% by weight has a sufficiently low melt viscosity to obtain a good molded article without further lowering the melt viscosity by widening the polymerization degree distribution width.
The above range is preferable for CPVC having an average chlorine content of more than 72% by weight because physical properties such as impact resistance are greatly reduced and are not suitable for practical use.

In the present invention, the method for producing PVC used as a raw material for CPVC is not particularly limited.
Examples thereof include a suspension polymerization method, an emulsion polymerization method, and a bulk polymerization method. Among them, a method based on the suspension polymerization method is preferable. The reason is that PVC obtained by the suspension polymerization method is obtained as porous fine particles. As for the particle diameter of PVC, 95% by weight or more of the whole PVC is 75 to 5%.
Preferably, the particle size is 00 μm. The reason is,
When fine particles of less than 75 μm and coarse particles of more than 500 μm increase, when thermoforming the obtained CPVC,
The reason for this is that the composition tends to vary, which causes thermal deterioration during heating, causing the molded product to be colored, and making it impossible to obtain a good molded product.

In the present invention, PVC used as a raw material for CPVC may be a homopolymer of vinyl chloride or a copolymer of vinyl chloride and another monomer. Other monomers, for example, vinylidene chloride, ethylene,
Examples include propylene, acrylonitrile, vinyl acetate, and methacrylic acid ester.

In the present invention, regardless of the method of chlorinating the PVC, which is generally known, the melt viscosity is low and the processability is improved while maintaining the excellent heat resistance of CPVC. CPVC is obtained. However, in practice, there has been a problem that coloring of the molded article becomes strong due to decomposition due to heat history during processing.

In order to improve the thermal stability of CPVC, a chlorination reaction was carried out by the method disclosed in JP-A-6-228226. Improved stability,
As a result, good workability, good appearance, and little coloring CP
It has been found that a VC molded body can be obtained.

That is, a method of suspending PVC in an aqueous medium in a sealable container, blowing nitrogen into the container to remove oxygen in the container, and introducing chlorine into the container to chlorinate PVC. In the chlorination process, 5 to PVC
100 ppm of hydrogen peroxide was added to the container,
Chlorinate PVC at a temperature of １４０140 ° C.

The hydrogen peroxide may be added before the introduction of chlorine as long as oxygen is removed from the container.
It may be after the introduction of chlorine. Alternatively, it may be near the end of the chlorination reaction of PVC.

The hydrogen peroxide may be added in the form of pure hydrogen peroxide, but is preferably added in the form of a solution. Particularly, it is preferable to add in the form of an aqueous solution. The amount of hydrogen peroxide to be added is preferably 5 to 100 ppm based on PVC. If the content is 5 ppm or less, the chlorination of PVC is not performed smoothly, and the thermal stability of the obtained CPVC is not improved. If the content is 100 ppm or more, the thermal stability of the obtained CPVC deteriorates.

Since the added hydrogen peroxide is gradually consumed in the course of the chlorination reaction, it is preferable that the addition of the hydrogen peroxide is not carried out at once but is carried out little by little over a long period of time. 30 minutes to one hour after the introduction of chlorine, the addition of hydrogen peroxide was started, and 3 hours at the end of the chlorination reaction.
More preferably, the addition of hydrogen peroxide is completed from 0 minutes to 1 hour before.

The chlorination reaction is 100 to 140
C. is preferred. If the temperature is lower than 100 ° C., the chlorination reaction rate is slow, and a long time is required for the chlorination. If the temperature exceeds 140 ° C., the chlorination and the dehydrochlorination reaction take place, and the obtained CPVC becomes colored.

In the present invention, PVC is suspended in an aqueous medium in a sealable container. The hermetically sealable container is preferably a glass-lined pressure-resistant container provided with a stirrer and a heating and cooling jacket. An appropriate amount of deionized water is put into the container, and then an appropriate amount of PVC powder is put into the container, and the inside of the container is stirred to disperse the PVC in the water and suspend the PVC in the water.

In the present invention, the PVC obtained as described above is used.
Remove oxygen from container with suspension. For this purpose, it is preferable that the inside of the container is first suctioned and deaerated using a vacuum pump. Suction is performed until the pressure in the container reaches, for example, a pressure of about 20 mmHg of mercury added to the vapor pressure of water at that time, and the first degassing is performed by maintaining this pressure for several minutes. Then, after nitrogen is injected into the container and left for a while, suction and deaeration is again performed by a vacuum pump to remove oxygen. This operation is repeated to reduce the amount of oxygen in the container to 100 ppm or less.

As described above, after removing oxygen in the container, chlorine is introduced into the container to chlorinate PVC. Pure chlorine is preferably introduced at that time, but commercially available chlorine may be used as it is. Commercial chlorine is 1000p
Although it contains oxygen of pm or more, in the present invention, such chlorine can be used as it is for chlorination of PVC.
In chlorination, hydrogen peroxide is added as described above and heated to maintain the above high temperature.

In the present invention, the pressure during the chlorination reaction is not particularly limited.
It is preferable to perform the reaction in a range in which a pressure of ~ 5.0 kg / cm ² is applied. If the pressure is low, the supply of chlorine will be insufficient, and the chlorination reaction will not proceed smoothly. If the pressure is high, the cost of the pressure-resistant container will increase, which is not advantageous.

[0036]

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

(Examples 1 to 10, Comparative Examples 1 to 10) A chain transfer agent and PVC whose average degree of polymerization was adjusted by changing the polymerization temperature were polymerized by a suspension polymerization method, and the average degree of polymerization was 400 to 800. Several types of PVC having different average degrees of polymerization in the range of less than were prepared. As shown in Tables 1 and 2, the obtained PVC was subjected to an average polymerization degree of each raw material PVC,
Mixing ratio, the average polymerization degree of the mixed PVC are chlorinated in a water suspension system under irradiation with a mercury lamp, and the average chlorine content reaches the values shown in 66.5% by weight and 68.5% by weight. Reacted. After removing hydrochloric acid and residual chlorine generated thereafter, dehydration and drying were performed to obtain CPVC. The molding processability (melt viscosity,
(Heat resistance, workability). Table 1 shows the results.
It is shown in FIG.

(Examples 11 to 22) PVC in which the average degree of polymerization was adjusted by changing the chain transfer agent and the polymerization temperature
Are polymerized by a suspension polymerization method, and several kinds of P having different average polymerization degrees are in the range of 400 to less than 800.
VC was produced. As shown in Table 3, the average degree of polymerization of each raw material PVC, the mixing ratio, and the
VC having an average degree of polymerization was chlorinated in a water suspension under irradiation with a mercury lamp, and reacted until the average chlorine content reached the values shown in 66.5% by weight and 68.5% by weight. After removing hydrochloric acid and residual chlorine generated thereafter, dehydration and drying were performed to obtain CPVC. Using the obtained CPVC, molding processability (melt viscosity, heat resistance, processability) was evaluated with the following composition. Table 3 shows the results.

The same raw material PVC as described above was used. As a chlorination method, about 10 ppm of hydrogen peroxide was added to PVC in the chlorination process without irradiation with a mercury lamp.
Using CPVC having an average chlorine content of 66.5% by weight and 68.5% by weight chlorinated at a temperature of 00 ° C., the following formula was evaluated for moldability and heat stability. Table 3 shows the results.

CPVC for evaluating the above moldability
Is 100 parts by weight of CPVC, 10 parts by weight of methyl methacrylate / butadiene / styrene copolymer resin, 0.5 parts by weight of methyl methacrylate resin, 2.0 parts by weight of dibutyltin maleate, and 0.5 parts by weight of butyl stearate. Was used.

[Melt Viscosity] Using a Koka type flow tester (manufactured by Shimadzu Corporation), CPVC was measured at 200 ° C. for 1 mm.
The measurement was performed under a load of 100 kg / cm ² using a dice having a length of φ × 1 mm. As a sample, a sheet was prepared by kneading the above composition with two 6-inch rolls at 200 ° C. for 2 minutes, and the sheet was cut into a size of about 5 mm × 5 mm. The melt viscosity (η) was determined by the following equation. Melt viscosity (η) = πPD ⁴ / 8LQ [where P = measurement pressure (dyne / cm ² ), D = die hole diameter (mm), L = die length (mm), Q = flow rate (cm ³⁾ / Sec). ]

[Heat resistance (flexible temperature)] After laminating the above sheets and preheating at 195 ° C for 3 minutes, the pressure was 150 kg / c.
A press plate processed to a thickness of 1 mm by press molding at m ² for 2 minutes was obtained. A test piece is cut out from this plate, and JIS K
The test method was based on the 6.545 softening temperature (softening temperature) test method for 6745 “hard vinyl chloride plate”.

[Workability] 1) Sheet surface properties The above composition was rolled at 200 ° C. × 2 using two 6-inch rolls.
The surface of the sheet prepared by kneading for minutes was observed with the naked eye.
Those at the intermediate level were marked with “△”. 2) Around the bank The state (around the bank) of the sheet wound around the roll during the sheet production was visually observed, and evaluated in order from good to “good”, “Δ”, and “x”. 3) Adhesive When taking out the sheet, "○" indicates that the sheet and the roll surface are easily peeled off, "X" indicates that the sheet is sticky and hardly peeled off.
Those with slight adhesion were marked with "△".

[Thermal Stability] 1) Aging Thermal Stability A test piece of about 4 cm × 4 cm was cut out from the above sheet.
These were put in a gear oven at 200 ° C. and taken out every 10 minutes, and the aging heat stability was shown by the time (minutes) until the sheet turned black. 2) Initial Colorability The above sheets were laminated, preheated at 195 ° C. for 4 minutes, and then press-molded at a pressure of 150 kg / cm ² for 5 minutes to obtain a pressed plate having a thickness of 3 mm. The yellowness of the press plate was measured using a color difference meter and indicated by a ΔYI value.

The average degree of polymerization of PVC and the average chlorine content of CPVC were determined by the following methods. (Average degree of polymerization of PVC) Measured according to 3.1 specific viscosity of JIS K 6721 "Testing method for vinyl chloride resin",
The average degree of polymerization was calculated. (Average chlorine content of CPVC) JIS K 7229
It was measured according to the oxygen flask combustion method of "Method for Quantifying Chlorine in Chlorine-Containing Resin", and the average chlorine content in the resin was shown by weight%.

[0046]

[Table 1]

[0047]

[Table 2]

[0048]

[Table 3]

[0049]

As described above, the CPVC of the present invention can be used as a raw material for PV.
The average degree of polymerization of C is 450 or more and less than 750, and the average degree of polymerization is 400 or more and 8
When two or more kinds of PVC less than 00 are mixed and used, by using the PVC mixed so that the difference between the lowest polymerization degree and the highest polymerization degree becomes 100 to 400 among the PVCs used for the mixing, Even at the same average polymerization degree, the melt viscosity is lower than that of CPVC obtained by using unmixed PVC as a raw material, and as a result, thermoformability is improved and a good molded product is obtained. Further, as a chlorination reaction method of the PVC, the thermal stability of CPVC is improved by adding 5 to 100 ppm of hydrogen peroxide to PVC during the chlorination process and performing the chlorination reaction at a temperature of 90 to 140 ° C. . As a result, a good molded product with improved thermoformability and less coloring can be obtained.

Claims (6)

[Claims] Claims: 1. A chlorinated vinyl chloride resin obtained by chlorinating a vinyl chloride resin, wherein the vinyl chloride resin comprises two kinds of vinyl chloride resins having an average degree of polymerization of less than 800. A chlorinated vinyl chloride resin characterized by being a mixture of the above. 2. The vinyl chloride resin has an average degree of polymerization of 450.
The chlorinated vinyl chloride resin according to claim 1, wherein a mixture of two or more kinds of vinyl chloride resins having different average polymerization degrees is used so as to be less than 750. 3. The chlorinated vinyl chloride resin according to claim 1, wherein the average chlorine content is 60 to 72% by weight. 4. The average degree of polymerization of the vinyl chloride resin used for mixing is 400 or more and less than 800, and the difference between the maximum and minimum of the average degree of polymerization of each vinyl chloride resin is 100 to 400. The chlorinated vinyl chloride resin according to any one of 1 to 3. 5. When producing a chlorinated vinyl chloride resin,
During the chlorination process, 5-10
0 ppm of hydrogen peroxide is added into the reaction vessel, and 90 to 1
The chlorinated vinyl chloride resin according to claim 1, wherein the chlorination reaction is performed at a temperature of 40C. 6. The chlorinated vinyl chloride resin according to claim 1, which is for thermoforming.