JPS5812892B2 - Method for producing vinyl chloride polymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vinyl chloride polymer and/or a vinyl chloride copolymer (hereinafter abbreviated as PvC).

).

More particularly, it relates to the production of PVC with high bulk density suitable for extrusion processing.

It is well known that it is economically preferable to use PvC with a high bulk density to improve the productivity of PVC extrusion processing.

However, the bulk density (measured according to JIS K-6721) of PVC produced by conventional suspension polymerization methods and bulk polymerization methods at normal polymerization temperatures (40 to 60° C.).

) is 0.45 to 0.59 g/cm3, and this PVC
In order to improve the productivity of extrusion molding using this method, a great deal of effort is required, such as improving the molding machine, improving the additives, and improving the method of adding additives.

Conventional methods for producing PVC with high bulk density without requiring such labor include suspension polymerization using a special dispersant, suspension polymerization by adding vinyl chloride monomer during polymerization, Gas phase polymerization methods using PvC produced by conventional suspension polymerization methods and bulk polymerization methods as a base material are well known, and it is well known that the latter two are superior.

In the method of suspension polymerization by adding vinyl chloride monomer during polymerization (for example, Japanese Patent Application Laid-Open No. 50-97679), JIS K
The bulk density measured according to -6721 is 0. 62kg
/cm3 or less, and gas-phase polymerization using PVC produced by conventional suspension polymerization or bulk polymerization as a base material (for example, Japanese Patent Publication No. 30290/1983, Japanese Patent Application Laid-Open No. 47-1999)
59.6, JIS K-
Bulk density measured according to 6721 is 0.63 g/cm
3 or less.

Compared to the conventional suspension polymerization method and bulk polymerization method, the bulk density of PVC produced by these two methods is not particularly superior.

As a result of intensive research, the present inventors have produced PVC with even higher bulk density, which does not require any improvement to conventional molding methods and can be extruded better than known methods. He found a method and completed his research.

That is, the gist of the present invention is as follows.

1. A vinyl chloride monomer and/or a monomer copolymerizable with the vinyl chloride monomer (hereinafter abbreviated as VCM).

) using a radical polymerization initiator at a pressure lower than the saturated vapor pressure of vinyl chloride monomer at the polymerization temperature, fine PvC having cohesive properties due to emulsifiers is used as a base material, and A method for producing a vinyl chloride polymer and/or a vinyl chloride copolymer, characterized in that the polymerization is carried out in a polymerization machine equipped with a device that stirs the agglomerated state of polymer particles without breaking them during polymerization. be.

2. In the above method, the base material is preferably made of PVC with a particle size of 0.01 to 10 microns.

3. It is also preferred that the base material consists of PvC which is polymerized with the addition of an emulsifier.

4. Furthermore, in the method 3 above, it is preferable that PvC be produced by fine suspension polymerization.

5. Further, it is preferable that the radical polymerization initiator is added dissolved in the liquid vinyl chloride monomer, impregnated into the base material, and then the vinyl chloride monomer is evaporated.

The details will be explained below.

The fine base material containing an emulsifier used in the present invention is preferably produced by the manufacturing method shown below, and the base material is coagulated in an atmosphere of vinyl chloride monomer vapor due to the emulsifier contained. have sex.

Manufacturing methods include adding additives such as emulsifiers to PVC produced by normal suspension polymerization, bulk polymerization, emulsion polymerization, and gas phase polymerization to give it cohesive properties; There are methods of imparting cohesive properties through suspension polymerization, bulk polymerization, and emulsion polymerization.In order to carry out the present invention more efficiently, there is a method of adding an emulsifier and performing suspension polymerization, bulk polymerization, and emulsion polymerization. Preferred and more preferred is the microsuspension polymerization method carried out according to Patent No. 661096.

As the polymerization initiator used in these polymerizations, water-soluble and oil-soluble polymerization initiators suitable for each polymerization method can be used, but water-soluble polymerization initiators include potassium persulfate,
Examples of oil-soluble polymerization initiators such as ammonium persulfate and hydrogen peroxide include azobisisobutyronitrile and azobisdimethylvaleronitrile (hereinafter abbreviated as ABVN).
Azo compounds such as, diisopropyl peroxydicarbonate (hereinafter abbreviated as DIPC), organic peroxides such as lauroyl peroxide, t-butyl peroxypiparate, etc. Radical polymerization initiators commonly used in vinyl chloride polymerization. agent is used.

Examples of emulsifiers include anions such as fatty acid salts, higher alcohol sulfate ester salts, liquid fatty oil sulfate ester salts, fatty alcohol phosphates, sulfonates of dibasic fatty acid esters, fatty acid amide sulfonates, and argylaryl sulfonates. type surfactants, and nonionic surfactants such as polyoxyethylene alkyl ethers and holoxyethylene alkyl esters may be used alone or in combination of two or more types.

Monoolefin monomers such as vinyl acetate, vinylidene chloride, and acrylonitrile are used as monomers copolymerizable with vinyl chloride monomers.

In addition, saturated aliphatic compounds, higher alcohols,
Stabilizers and the like may be used as additives.

As the polymerization temperature, a commonly used 40 to 70°C is employed.

Further, the particle size of the base material used in the present invention is 0.01 to
10μ is preferred.

It is well known that when the particle size is less than 0.01 μm, the bulk density is extremely low and industrial handling is difficult, and when the particle size exceeds 10 μm, it becomes difficult to impart cohesiveness to the particles.

Next, we will discuss a method of polymerizing PVC using the above-mentioned base material used in the present invention at a polymerization pressure lower than the saturated vapor pressure of vinyl chloride monomer at the polymerization temperature (usually referred to as a gas phase polymerization method). explain.

The polymerization pressure (expressed in Pp) is as well known (for example, Japanese Patent Publication No. 46-30290, Japanese Patent Publication No. 47-596).
, Japanese Patent Publication No. 48-14666, etc.), the pressure is lower than the saturated vapor pressure (represented by P8) of vinyl chloride monomer at the polymerization temperature, and the ratio of the pressures (represented by Pr, Pr = P, /P
, 0.45<P<1 is used.

The polymerization temperature may be any temperature normally used for polymerizing vinyl chloride, and 40 to 70°C is employed.

The polymerization time is preferably between 1 and 12 hours and can be selected as appropriate.

The polymerization initiator used is an oil-soluble radical polymerization initiator that is commonly used for vinyl chloride polymerization, such as azo compounds such as azobisisobutyronitrile and ABVN, and organic peroxides such as DIPC and lauroyl peroxide. .

The above-mentioned methods of adding the polymerization initiator include a method of directly adding the polymerization initiator, a method of dissolving the polymerization initiator in liquid vinyl chloride monomer and adding it, and then evaporating only the vinyl chloride monomer. A solvent that is inert to the base material (
A method is adopted in which the polymerization initiator is diluted and added to liquid vinyl chloride monomer (for example, methanol, cyclohexane, etc.) and then only the solvent is removed. A method is adopted in which only the vinyl monomer is evaporated.

It is well known that the method of diluting and adding a polymerization initiator to a commonly used solvent that is inert to potash-based substances and then removing only the solvent is undesirable from economical and environmental standpoints.

In addition, the method of directly adding a polymerization initiator requires special measures to uniformly disperse the polymerization initiator in the base material, and in particular, powdered polymerization initiators (e.g., lauroyl peroxide, bis-4, Tert-butyl, cyclohexyl, peroxydicarbonate, etc.) are difficult to uniformly disperse. I don't like it.

The type of polymerization apparatus has a device (for example, a double helical band blade, a double helical cone blade, a helical screw blade, etc.) that stirs the agglomerated state of cohesive polymer particles without breaking them during polymerization. A type of polymerization machine is adopted.

The present invention can also be carried out in a gas flow polymerization machine having a similar stirring device.

Further, the operation format may be either a batch reaction or a continuous reaction.

Compared to conventional methods, the PVC produced by the present invention has
P with high bulk density that enables extrusion molding with high productivity
The fact that it is vC is as shown in Table 1.

The present invention will be explained below based on Examples.

Example 1 (1) Production of base material A base material was produced by a fine suspension polymerization method according to Patent No. 661096.

That is, 100 liters of vinyl chloride was placed in a 50 liter pressure-resistant stainless steel reactor.
200 parts of pure water, 0.03 parts of ABVN and dodecylbenzenesulfone as an emulsifier} o. After containing 6 parts and 0.6 parts of cetanol and replacing the air with nitrogen gas,
This was dispersed and homogenized by passing it through a colloid mill for 2 hours.

The system was heated to 58°C and stirred at 50 rpm/min.
Polymerization was carried out for 1 hour.

(2) Gas phase polymerization method 100 parts of liquid vinyl chloride, 0.2 parts of DIPC, and 50 parts of the above base material were placed in a stainless steel polymerization machine with an internal volume of 1 liter equipped with double helical band blades, and DI was carried out while stirring gently.
PC was impregnated into the base material, and liquid vinyl chloride was removed by vaporization.

After degassing this with a vacuum pump, the temperature of the system was raised and maintained at 62°C, and the vapor pressure was 7. 1 kg/cmG of vinyl chloride vapor was introduced into the polymerization machine through a connecting pipe, and the polymerization pressure was increased to 7.5 kg/cmG. 1
The polymerization was carried out by maintaining the weight at kg/cm2G during the polymerization.

Pr at this time is 0.75. After 2 hours, the valve of the communication pipe was closed, the vinyl chloride vapor in the polymerization machine was discharged, and the polymerization was stopped.

The bulk density of the PVC obtained after polymerization is 0.71 g/cm3 (
Measured according to JIS K-6721.

), and as shown in Table 1, PvC has a superior bulk density compared to PvC produced by conventional polymerization methods.

Example 2 (1) Production of base material Same as Example 1.

(2) Method of gas phase polymerization The amount of DIPC is 0.4 parts, the polymerization temperature is 58°C, and the polymerization pressure is 6.5 kg/cm2G (this results in Pr=0.78).

) and the polymerization time was changed to 1.5 hours, and the same polymerization as in Example 1 was carried out.

The bulk density of the PvC obtained after polymerization was 0.70 g/cm3.

Example 3 (1) Production of base material Same as Example 1, but polymerization was carried out at a polymerization temperature of 45°C.

(2) Method of gas phase polymerization Using 50 parts of the above base material, the polymerization temperature was 58°C, and the polymerization pressure was 6.5%. Polymerization was carried out in the same manner as in Example 1 except that the weight was 5 kg/cm2G and the polymerization time was changed to 3 hours.

The bulk density of the PVC obtained after polymerization was 0.70 g/cm3.

Example 4 (1) Production of base material Same as Example 1, but the emulsifier was changed from dodecylbenzenesulfonate to alkyl sulfate, and polymerization was carried out at a polymerization temperature of 52°C.

(2) Method of gas phase polymerization Polymerization was carried out in the same manner as in Example 3 using 50 parts of the above base material.

The bulk density of the PVC obtained after polymerization was 0.77 g/cm3.

Next, a known gas phase polymerization method (for example, Japanese Patent Publication No. 46-30
290, JP-A-47-596, JP-A-48-14666
Comparative examples using PVC made by the usual suspension polymerization method and PVC made by the bulk polymerization method used as the base materials are shown below.

Comparative example 1 (1) Production of base material It was manufactured by a known suspension polymerization method.

That is, 200 kg of liquid vinyl chloride, 450 kg of pure water, 180 g of partially saponified polyvinyl acetate, and 50 g of ABVN were placed in a stainless steel polymerization machine with a capacity of 1 m 3 and polymerized at a polymerization temperature of 58° C. to a polymerization yield of 80%.

(2) Method of gas phase polymerization Polymerization was carried out in the same manner as in Example 1 using 50 parts of the above base material and setting the polymerization time to 4 hours.

The bulk density of the PVC obtained after polymerization was 0.62 t/cri.

Comparative example 2 (1) Production of base material This is the same as Comparative Example 1.

(2) Method of gas phase polymerization Polymerization was carried out in the same manner as in Example 1 using 50 parts of the above base material.

The bulk density of the PvC obtained after polymerization was 0.56 g/cm3.

Comparative Example 3 (1) Production of base material Same as Comparative Example 1, but polymerization was stopped when the polymerization yield was 30%.

(2) Method of gas phase polymerization Polymerization was carried out in the same manner as in Comparative Example 1 using 30 parts of the above base material and 0.1 part of DIPC.

The bulk density of the PVC obtained after polymerization is o. 45f//cri
It was t.

Comparative Example 4 (1) Bulk polymerized polyvinyl chloride manufactured by Rhone Poulenc (trade name GB-11150) having a production average degree of polymerization of 965 as a base material was used.

(2) Method of gas phase polymerization Polymerization was carried out in the same manner as in Example 3 using 50 parts of the above base material.

The bulk density of PVC obtained after polymerization is 0.63? /cWL.

Example 5 (1) Production of base material The same procedure as in Example 1 was carried out, except that 10 parts of vinyl acetate was further added for polymerization.

It is a copolymer of vinyl chloride and vinyl acetate.

(2) Method of gas phase polymerization Polymerization was carried out in the same manner as in Example 3, using 50 parts of the above base material and setting the polymerization time to 2 hours.

The bulk density of the PVC obtained after polymerization was 0.70 g/cm3.

Table 2 summarizes the above results.

From Table 2, PvC obtained by gas phase polymerization using a PvC having a particle size of 0.01 to 10μ and having cohesive properties in a vinyl chloride vapor atmosphere produced by a fine suspension polymerization method as a base material. It is clear that the bulk density of PvC is high and excellent, and even if the particle size exceeds 10μ and the non-agglomerating PvC is used as a base material in a gas phase polymerization in a vinyl chloride vapor atmosphere, it has a particularly excellent bulk density. It can be seen that the density of PVC cannot be obtained.

Comparative Example 5 (1) Production of base material Same as Example 1, except that no emulsifier was used, and 0.3 parts of methyl cellulose was used as a dispersant for polymerization, and then classified.

The particle size of this base material was in the range of 5 to 10 microns.

(2) Method of gas phase polymerization Polymerization was carried out in the same manner as in Example 3 using 50 parts of the above base material and setting the polymerization time to 2 hours.

The bulk density of the PvC obtained after polymerization is 0.25 g/cm3, and even if the particle size is 0.01 to 10 μ, it can be polymerized in a gas phase using a non-cohesive base material in a vinyl chloride vapor atmosphere. It turns out that PVC with excellent bulk density cannot be obtained.

Example 6 (1) Production of base material Manufactured by emulsion polymerization method.

In other words, in the 201 polymerization machine, 8. 210 g of a vinyl chloride polymer weighing 4 kg and having a particle size of 0.3 μm, and 2.1 g of ammonium peroxide were stored, and the polymerization machine was depressurized and replaced with nitrogen.

Subsequently, 7 kg of liquid vinyl chloride was added, and the temperature was raised to 50°C to start polymerization.

Further, during the polymerization, 427 times of sodium laurate was continuously added until the polymerization yield increased from 10% to 70%.

When the polymerization pressure reached 5 kg/cm2G, the polymerization was stopped and unreacted vinyl chloride was recovered.

(2) Method of gas phase polymerization Polymerization was carried out in the same manner as in Example 3, using 50 parts of the above base material and setting the polymerization time to 4 hours.

The bulk density of the PvC obtained after polymerization is 0.67 g/cm3.

According to this example, when vinyl chloride is vapor-phase polymerized using a base material produced by an emulsion polymerization method and having a particle size of 0.01 to 10μ and having cohesive properties in vinyl chloride vapor, an excellent bulk density is obtained. It can be seen that PVC can be obtained.

Comparative example 6 (1) Production of base material Same as Example 6.

(2) Method of gas phase polymerization A normal fluidized bed made of a stainless steel tube with an inner diameter of 5 cm and a length of 60 cm equipped with a mantle and without any mechanical stirring device is impregnated with 0.2 part of DIPC. 50 g of base material was contained and degassed with a vacuum pump.

Thereafter, the temperature of the system was raised and maintained at 58°C, and the vapor pressure was 7. 1k
Vinyl chloride vapor of g/cmG was introduced from below, and the base material was polymerized for 4 hours while flowing.

The bulk density of the PVC obtained after polymerization was 0.60 g/cm3.

Coagulates in vinyl chloride vapor and has a particle size of 0.0
When the above base material having a diameter of 1 to 10μ is fluidized in a fluidized bed,
Some of the particles agglomerate, and the diameter distribution of the agglomerated particles is remarkable in the higher direction of the fluidized bed, resulting in a decrease in the PV obtained by polymerization.
It was found that the bulk density of C did not increase.

Comparative example 7 (1) Production of base material Same as Example 6.

(2) Method of gas phase polymerization According to the method shown in Example 5 of Japanese Patent Publication No. 48-14666,
The above base substance 507 and 0.5 part of finely powdered bis-4-tert-butyl-cyclohexyl peroxydicarbonate are thoroughly mixed to form a stainless steel polymer with an inner volume of 1 liter and equipped with double helical band blades. It was accommodated in the aircraft.

After degassing this with a vacuum pump, the same polymerization as in Example 3 was carried out.

The bulk density of the PVC obtained after polymerization was 0.54 g/cm3.

Thus, it can be seen that the effects of the present invention cannot be improved if the polymerization initiator is non-uniformly dispersed in the base material.

Claims (1)

[Claims] 1. Vinyl chloride monomer and/or vinyl chloride monomer and a monomer copolymerizable therewith are treated with radicals at a polymerization pressure lower than the saturated vapor pressure of vinyl chloride monomer at the polymerization temperature. When performing polymerization using a polymerization initiator, fine vinyl chloride polymers and/or vinyl chloride copolymers with cohesive properties are used as base materials by emulsifiers, and the agglomerated state of polymer particles having cohesive properties is controlled during polymerization. 1. A method for producing a vinyl chloride polymer, characterized in that polymerization is carried out in a polymerization machine equipped with a device for stirring without breaking the polymer. 2. The manufacturing method according to claim 1, wherein the particle size of the base material is in the range of 0.01 to 10 μm. 3. The manufacturing method according to claim 1, wherein the base material is obtained by polymerizing in the presence of an emulsifier. 4. The manufacturing method according to claim 3, wherein the base material is manufactured by a fine suspension polymerization method. 5. The manufacturing method according to claim 1, wherein the radical polymerization initiator is added dissolved in liquid vinyl chloride monomer, impregnated into the base material, and then the vinyl chloride monomer is evaporated.