JPH07304808A - Production of vinyl chloride-based resin - Google Patents

Abstract

PURPOSE:To provide a method for producing a vinyl chloride-based resin by which particles having a high bulk specific gravity with few fish eyes are obtained. CONSTITUTION:The method for producing a vinyl chloride-based resin is to add a partially saponified polyvinyl acetate having 79-89 mol% degree of saponification and 1000-3500 average degree of polymerization and an 8-30C fatty acid, or the partially saponified polyvinyl acetate having 79-89 mol% degree of saponification and 1000-3500 average degree of polymerization and another having 60-73mol%, degree of saponification and 400-2000 average degree of polymerization and control the net agitating power to 2.1-4.5 kW/m<3> in a method for carrying out the suspension polymerization of a vinyl chloride-based monomer in the presence of an oil-soluble polymerization initiator in an aqueous medium, and producing the vinyl chloride resin.

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 vinyl chloride resin which has a high bulk specific gravity and is excellent in productivity and processability.

[0002]

2. Description of the Related Art Vinyl chloride resins are used in many applications as materials having excellent properties such as mechanical strength, weather resistance and chemical resistance. However, since there is a defect in workability, improvement thereof is desired.

It has been known that the processability of vinyl chloride resin is greatly influenced by the bulk specific gravity and particle size distribution of vinyl chloride resin particles. Especially, when the bulk specific gravity is improved, the chloride obtained by a single polymerization operation is obtained. Vinyl resin production increased,
Further, torque is easily applied to the extruder during the molding process, the amount of extrusion per unit time increases, and the processability is improved. Therefore, it is desired to manufacture a resin having a high bulk specific gravity.

The bulk specific gravity is determined by the size, shape and particle size distribution of the vinyl chloride resin particles and the packing rate of primary particles inside the vinyl chloride resin particles. As a method for increasing the bulk specific gravity by increasing the filling rate of the primary particles inside the vinyl chloride resin particles, for example, a method in which a monomer is post-added during polymerization is disclosed in JP-A-50-97679 and JP-A- No. 57-192411. However, in this method, although the filling rate of the primary particles is improved and the specific gravity is improved, the polymerization operation is complicated, and there is a problem that the fish eyes are increased and the gelation property and the physical properties of the molded product are deteriorated. .

As a method for obtaining a resin having a high bulk specific gravity by specifying the saponification degree, viscosity and amount of the dispersant,
For example, JP-A-62-101609 and JP-A-62.
JP-A-260803, a high-saponification degree polyvinyl acetate having a saponification degree of 85 to 90 mol% is used as a main dispersant, and a saponification degree of 6 is used.
A method for improving bulk specific gravity by using together polyvinyl acetate having a low saponification degree of 5 to 75 mol% or a saponification degree of 35 to 50 mol% is disclosed. However, according to these methods, the bulk specific gravity was improved, but an increase in fish eyes could not be avoided.

On the other hand, in JP-A-61-1141703, a saponification degree of 70 to 85 mol% and a high saponification degree of 85 mol% or more are used with polyvinyl acetate as a main dispersant. A method is disclosed in which polyvinyl acetate or the like having a high protective colloid property is used in combination. However, these methods did not sufficiently improve the bulk specific gravity.

[0007]

SUMMARY OF THE INVENTION In view of the above, it is an object of the present invention to provide a method for producing a vinyl chloride resin, which can obtain particles having a small number of fish eyes and a high bulk specific gravity.

[0008]

The gist of the present invention is a method for producing a vinyl chloride resin in which a vinyl chloride monomer is suspension-polymerized in an aqueous medium in the presence of an oil-soluble initiator. ˜89 mol%, partially saponified polyvinyl acetate having an average degree of polymerization of 1000 to 3500 and a fatty acid having 8 to 30 carbon atoms, and a net stirring power of 2.1 to 4.5 kW / m ³ to give a vinyl chloride resin. It is in the place of manufacturing.

The partially saponified polyvinyl acetate has a saponification degree of 79 to 89 mol%. If the saponification degree is less than 79 mol%, a vinyl chloride resin having a high bulk specific gravity cannot be obtained,
If it exceeds 9 mol%, the vinyl chloride resin becomes coarser particles as the protective colloid property deteriorates, so the content is limited to the above range. More preferably, it is 80 to 88 mol%.

The average degree of polymerization of the partially saponified polyvinyl acetate is 1000 to 3500. Average degree of polymerization is 1000
If it is less than 3, the viscosity and interfacial tension of the reaction mixture solution cannot be obtained, so that the vinyl chloride resin becomes coarse particles, and a vinyl chloride resin having a high bulk specific gravity cannot be obtained. If it exceeds 3500, the solubility in water is low and the dispersion is low. Since the vinyl chloride resin having a sharp particle size distribution cannot be obtained due to its low ability, it is limited to the above range. More preferably, it is 1500 to 3000.

The fatty acid has 8 to 30 carbon atoms. When the carbon number is less than 8, the fatty acid has a water-soluble property and is not distributed to the oil layer during the polymerization, so that the gelation promoting effect is not exhibited, and when the carbon number exceeds 30, the melting point of the fatty acid becomes high and the molding is performed. Sometimes the gelation promotion effect is not exerted, so
It is limited to the above range. More preferably, it is 11-25. The amount of the fatty acid added is preferably 300 ppm to 20000 ppm with respect to the vinyl chloride monomer. If the addition amount is less than 300 ppm, the gelation promoting effect cannot be obtained,
If it exceeds 000 ppm, it takes a long time to gel.

The net stirring power during the polymerization is 2.1-4.
It is 5 kW / m ³ . Here, the net stirring power is 1 m of the content liquid during polymerization, which does not include the loss in the speed reduction mechanism section or the shaft sealing section.
It is the stirring power per ³ . Net stirring power is 2.1kW
If it is less than / m ³ , fish eyes increase and coarse particles of the vinyl chloride resin are caused, and since the particle shape deviates from the spherical shape, a vinyl chloride resin having a high bulk density cannot be obtained,
If it exceeds 4.5 kW / m ³ , a vinyl chloride resin having a sharp particle size distribution cannot be obtained, and the filling rate of the primary particles inside the particles becomes low, so that a vinyl chloride resin having a high bulk specific gravity cannot be obtained. Is limited to the above range. More preferably, it is 2.3 to 3.5 kW / m ³ .

The oil-soluble polymerization initiator used in the present invention is
It may be one commonly used in the polymerization of vinyl chloride resins, for example, organic peroxides such as benzoyl peroxide, lauroyl peroxide, 2-ethylhexyl peroxydicarbonate; azobisisobutylnitrile, azobisisovaleronitrile. And the like, and one or more of them are used. Of these, organic peroxides are more preferable.

In the present invention, a monomer copolymerizable with vinyl chloride can be used as the copolymerization component.
These are not particularly limited, and examples thereof include alkyl vinyl esters such as vinyl acetate; α-such as ethylene and propylene.
Mono-olefins; vinylidene chloride, styrene and the like can be mentioned.

In the present invention, the method for charging deionized water, vinyl chloride monomer, and optionally vinyl monomer other than vinyl chloride, etc. to the reaction system, and the olefin degassing method may be the same as conventional methods. A polymerization regulator, a chain transfer agent, an antistatic agent, a crosslinking agent, a stabilizer, a filler, an anti-scale agent, etc. may be added depending on the polymerization conditions.

The shape and structure of the polymerization vessel (pressure resistant autoclave) may be those conventionally used and are not particularly limited. The stirring blade may be a commonly used one such as a Faudler, paddle, or turbine, and the combination with the baffle plate is not particularly limited.

The present invention 2 is a method for producing a vinyl chloride resin in which a vinyl chloride monomer is suspension-polymerized in an aqueous medium in the presence of an oil-soluble initiator, wherein the saponification degree is 79 to 89 mol%,
Partially saponified polyvinyl acetate having an average degree of polymerization of 1000 to 3500, a degree of saponification of 60 to 73 mol%, and an average degree of polymerization of 400.
It is a method for producing a vinyl chloride resin by adding 2,000 to 2,000 partially saponified polyvinyl acetate and setting the net stirring power to 2.1 to 4.5 kW / m ³ .

The degree of saponification of the partially saponified polyvinyl acetate is 60 to 73 mol%. When the saponification degree is less than 60 mol%, the dispersant has a large oil solubility, and not only the solubility in water is low, but also the dispersibility is low, resulting in no effect.
If it exceeds 3 mol%, the formation of fish eyes is promoted, and the gelling property and workability and moldability are deteriorated, so the content is limited to the above range. It is more preferably 65 to 72 mol%. The average degree of polymerization of the partially saponified polyvinyl acetate is 400 to 20.
00. If it is less than 400, the viscosity and interfacial tension of the reaction mixture solution cannot be obtained, so that the vinyl chloride resin becomes coarse particles, and the vinyl chloride resin having a high bulk specific gravity cannot be obtained.
If it exceeds 00, the solubility in water is low and the dispersibility is low, so that a vinyl chloride resin having a sharp particle size distribution cannot be obtained. Therefore, it is limited to the above range. More preferably 60
It is 0-1700.

[0019]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

Example 1 50 kg of deionized water and partially saponified polyvinyl acetate (saponification degree 82%, average degree of polymerization 2200) were added to a reaction vessel having an internal volume of 100 L (pressure autoclave) at 500 ppm with respect to vinyl chloride monomer. Then, 1000 ppm of stearic acid was added to the vinyl chloride monomer, and 500 ppm of t-butylperoxy neodecanoate was added to the vinyl chloride monomer. After degassing the inside of the reaction vessel to 45 mmHg, 33 kg of vinyl chloride monomer was charged. The content was agitated while controlling the net agitation power to 2.2 kW / m ³ . The polymerization temperature was 57 ° C., and this temperature was maintained until the completion of the polymerization. The reaction was terminated when the polymerization conversion rate reached 90%, the unreacted monomer in the reaction vessel was recovered, and then the polymer was taken out of the system in a slurry form and dehydrated and dried. The following tests were conducted on the obtained vinyl chloride resin.

Bulk specific gravity was measured according to JIS K 6721, and the results are shown in Table 1. Particle size distribution In accordance with JIS Z 8801, 60, 100, 20
It was sieved using a 0 mesh sieve and the passing amount (% by weight) was calculated. The results are shown in Table 1. Fish eye 50 g of vinyl chloride resin obtained, 10 g of adipic acid polyester plasticizer, anthraquinone blue pigment 0.2
5 g, barium-zinc-based liquid stabilizer 0.3 g, organic epoxy-based stabilizer 0.5 g, and barium-zinc-based powdery stabilizer 0.1 g were mixed and kneaded on a roll at a surface temperature of 160 ° C. for 7 minutes. A sheet having a thickness of 0.7 mm was pulled out.
10 cm of this sheet, shining light from the back side of this sheet
The number of glass bead particles (fish eyes) observed in an area of × 10 cm was determined. The results are shown in Table 1. Processability (gelation performance) Montane ester (WAX OP, manufactured by Hoechst) as a lubricant for 100 parts by weight of the vinyl chloride resin.
0.5 parts by weight, dibutyltin mercapto (J
2 parts by weight of F-10B (manufactured by Sankyo Machine Gosei Co., Ltd.) were heated to 120 ° C. with a super mixer (manufactured by Mitsui Miike Co., Ltd.) and mixed 4
Cooled to 0 ° C. 60 g of the resin taken out was put into a plastomill (manufactured by Toyo Seiki Co., Ltd.), the rotation speed was 50 rpm, and the temperature was raised from the input temperature of 120 ° C. at a rate of 5 ° C./min to 200 ° C. for gelation time and maximum torque. It was measured. A resin with a short gelling time and a low maximum torque was defined as having good workability (gelling performance).

Example 2, Comparative Examples 2 to 7 Vinyl chloride resin was obtained in the same manner as in Example 1 except that the dispersant, fatty acid and net stirring power shown in Table 1 were used.
The test was conducted and the results are shown in Table 1.

Example 3 50 kg of deionized water and partially saponified polyvinyl acetate (saponification degree 89%, average degree of polymerization 1500) were added to a reaction vessel having an internal volume of 100 L (pressure autoclave) at 500 ppm with respect to vinyl chloride monomer. , Lauric acid was added to the vinyl chloride monomer at 2000 ppm, and t-butylperoxy neodecanoate was added to the vinyl chloride monomer at 500 ppm. After degassing the inside of the reaction vessel to 45 mmHg, 33 kg of vinyl chloride monomer was charged. Net stirring power is 3.
The contents were stirred while controlling at 0 kW / m ³ . The polymerization temperature was 57 ° C., and this temperature was maintained until the completion of the polymerization. The reaction was terminated when the polymerization conversion rate reached 90%, the unreacted monomer in the reaction vessel was recovered, and then the polymer was taken out of the system in a slurry form and dehydrated and dried. The test described in Example 1 was performed on the obtained vinyl chloride resin, and the results are shown in Table 1.

Comparative Example 1 50 kg of deionized water and partially saponified polyvinyl acetate (saponification degree 82%, average degree of polymerization 2200) were placed in a reaction vessel having an internal volume of 100 L (pressure autoclave) at 500 ppm with respect to vinyl chloride monomer. , Propionic acid was added to the vinyl chloride monomer at 1000 ppm, and t-butylperoxy neodecanoate was added to the vinyl chloride monomer at 500 ppm. After degassing the inside of the reaction vessel to 45 mmHg, 33 kg of vinyl chloride monomer was charged. The content was agitated while controlling the net agitation power to 2.2 kW / m ³ . The polymerization temperature was 57 ° C., and this temperature was maintained until the completion of the polymerization. The reaction was terminated when the polymerization conversion rate reached 90%, the unreacted monomer in the reaction vessel was recovered, and then the polymer was taken out of the system in a slurry form and dehydrated and dried. The test described in Example 1 was performed on the obtained vinyl chloride resin, and the results are shown in Table 1.

[0025]

[Table 1]

Example 4 50 kg of deionized water and partially saponified polyvinyl acetate (saponification degree: 82 mol%, average degree of polymerization: 2200) were placed in a reaction vessel having an internal volume of 100 L (pressure-resistant autoclave) with respect to a vinyl chloride monomer. 300 ppm, partially saponified polyvinyl acetate (saponification degree 68 mol%, average degree of polymerization 800) to vinyl chloride monomer 200 ppm, t-butyl peroxyneodecanoate to vinyl chloride monomer 500p
pm was added. After degassing the inside of the reaction vessel to 45 mmHg, 33 kg of vinyl chloride monomer was charged. The content was agitated while controlling the net agitation power to 2.2 kW / m ³ . The polymerization temperature was 57 ° C., and this temperature was maintained until the completion of the polymerization.
The reaction was terminated when the polymerization conversion rate reached 90%, the unreacted monomer in the reaction vessel was recovered, and then the polymer was taken out of the system in a slurry form and dehydrated and dried. The vinyl chloride resin thus obtained was tested in the same manner as in Example 1, and the results are shown in Table 2.

Comparative Example 8 50 kg of deionized water and partially saponified polyvinyl acetate (saponification degree: 82 mol%, average degree of polymerization: 2200) were added to a vinyl chloride monomer in a reaction vessel (pressure-resistant autoclave) having an internal volume of 100 L. 300 ppm, partially saponified polyvinyl acetate (saponification degree 55 mol%, average degree of polymerization 800) to vinyl chloride monomer 200 ppm, t-butyl peroxyneodecanoate to vinyl chloride monomer 500p
pm was added. After degassing the inside of the reaction vessel to 45 mmHg, 33 kg of vinyl chloride monomer was charged. The content was agitated while controlling the net agitation power to 2.2 kW / m ³ . The polymerization temperature was 57 ° C., and this temperature was maintained until the completion of the polymerization.
The reaction was terminated when the polymerization conversion rate reached 90%, the unreacted monomer in the reaction vessel was recovered, and then the polymer was taken out of the system in a slurry form and dehydrated and dried. The vinyl chloride resin thus obtained was tested in the same manner as in Example 1, and the results are shown in Table 2.

Example 5, Comparative Examples 9 to 15 Table 2 shows the degree of saponification, the degree of polymerization and the amount of addition of the partially saponified polyvinyl acetate and the partially saponified polyvinyl acetate used as the dispersant, and the net stirring power. A vinyl chloride resin was prepared in the same manner as in Example 4 except that the indicated ones were used. The vinyl chloride resin thus obtained was tested in the same manner as in Example 1, and the results are shown in Table 2.

[0029]

[Table 2]

[0030]

Since the method of the present invention is as described above,
It is possible to provide a vinyl chloride resin having a high bulk specific gravity, a sharp particle size distribution, and excellent workability.

Claims (2)

[Claims] 1. A method for producing a vinyl chloride resin in which a vinyl chloride monomer is suspension-polymerized in an aqueous medium in the presence of an oil-soluble initiator, wherein a saponification degree is 79 to 89 mol% and an average polymerization degree is 1000 to 3500 partially saponified polyvinyl acetate and fatty acid having 8 to 30 carbon atoms were added, and the net stirring power was 2.1.
~ 4.5 kW / m ^{3 A} method for producing a vinyl chloride resin. 2. A method for producing a vinyl chloride resin, which comprises suspension-polymerizing a vinyl chloride monomer in an aqueous medium in the presence of an oil-soluble initiator, wherein the saponification degree is 79 to 89 mol%, and the average degree of polymerization is 1000 to Partially saponified polyvinyl acetate of 3500 and saponification degree of 60 to 73 mol%, average degree of polymerization of 400 to 2000
4. The method for producing a vinyl chloride-based resin, comprising adding the partially saponified polyvinyl acetate described in 1. above and adjusting the net stirring power to 2.1 to 4.5 kW / m ³ .