JP3167142B2 - Method for producing vinyl chloride resin - Google Patents

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 (hereinafter abbreviated as PVC).
Improving the method of recovering unpolymerized monomers using a reflux condenser attached to the polymerization machine greatly improves polymerization productivity and greatly increases the cost of reusing recovered unpolymerized monomers. The present invention relates to a method for producing a vinyl chloride resin to be reduced.

[0002]

2. Description of the Related Art Conventionally, in the production of PVC, in order to increase polymerization productivity as much as possible by using a polymerization machine having a fixed capacity, a pre-polymerization method such as charging depolymerized or preheated polymerization water into the polymerization machine is used. Various measures have been studied and developed to shorten the time required for one cycle of batch polymerization, such as shortening the working time, shortening the polymerization reaction time by selecting the polymerization initiator, and omitting and simplifying the cleaning inside the polymerization machine using the scale adhesion prevention technology. It has been. As one of these methods, a method using a reflux condenser for the purpose of efficiently removing the heat of the polymerization reaction and shortening the polymerization reaction time is a well-known technique. The method conventionally used for the recovery of unpolymerized monomer in the production of PVC is to open the recovery valve of the polymerization machine, guide the gaseous monomer to the gas holder, and purify the monomer after compression liquefaction. Things. In this case, since the monomer is handled in a vaporized state, the recovery capacity is large, and the recovery speed needs to be suppressed so that the vaporized monomer does not entrap the resin in the polymerization machine and block the recovery pipe. Therefore, it takes a long time to collect. In addition, liquefaction and purification of the recovered unpolymerized monomer in a compressed state are disadvantageous because they require a large cost.

[0003]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention significantly shortens the time required for recovering unpolymerized monomers, and polymerizes the recovered unpolymerized monomers without liquefaction and purification. An object of the present invention is to provide a method for producing a vinyl chloride resin that can be used as a monomer for charging.

[0004]

Means for Solving the Problems The inventors of the present invention have made intensive studies to achieve the above object, and as a result, have collected liquefied unpolymerized monomer refluxed from a reflux condenser in a recovery tank. The present inventors have found that the above-mentioned object can be achieved by overcoming the drawbacks of the conventional recovery method in which a vaporized unpolymerized monomer is led to a gas holder, and have reached the present invention.

That is, the present invention relates to the polymerization of a vinyl chloride monomer alone or a mixture of a vinyl chloride monomer and another monomer copolymerizable therewith using a polymerization machine having a reflux condenser provided outside the apparatus. Wherein the liquefied unpolymerized monomer refluxed from the reflux condenser is recovered in a recovery tank attached to the outside of the polymerization machine when the polymerization is completed and the unpolymerized monomer is recovered. The subject of the present invention is a method for producing a base resin.

In the present invention, the timing and the rate of recovery of the liquefied unpolymerized monomer condensed by the reflux condenser are not particularly limited. However, the timing of the recovery is not limited to the quality of the product PVC [porosity (porosity). Porosity) and bulk specific gravity], and the recovery rate is appropriately determined on the condition that unpolymerized monomers rising from the polymerization reaction solution to the reflux condenser do not accompany the resin in the polymerization reaction solution. Just do it.

In the recovery of the unpolymerized monomer, not only the method of recovering the liquefied unpolymerized monomer from the reflux condenser into the recovery tank, but also this method and the method using the gas holder May be employed in combination with the conventional method of recovering wastewater. The liquefied unpolymerized monomer recovered in the recovery tank can be used without purification as a monomer for polymerization preparation, and is compressed and liquefied and purified as compared with the method of recovering vaporized unpolymerized monomer. Is unnecessary, which is advantageous in cost.

The present invention can be used in various polymerization methods such as suspension polymerization, microsuspension polymerization, emulsion polymerization, bulk polymerization, and solution polymerization, and the polymerization method is not particularly limited.

In the present invention, other monomers copolymerizable with the vinyl chloride monomer include olefins such as ethylene and propylene, vinyl esters such as vinyl acetate and vinyl stearate, methyl acrylate, and the like. Acrylic esters such as methyl methacrylate; esters and anhydrides of acids such as maleic acid or fumaric acid; nitrile compounds such as acrylonitrile; and vinylidene compounds such as vinylidene chloride.
Used in combination of more than one species.

As the polymerization initiator used in the present invention, an oil-soluble initiator or a water-soluble initiator usually used in polymerization of vinyl chloride is used. As the oil-soluble initiator,
For example, lauroyl peroxide, 3,5,5-trimethylhexanoyl peroxide, t-butylperoxypivalate, t-butylperoxyneodecanate,
Organic peroxides such as diisopropylperoxydicarbonate, di-2-ethylhexylperoxydicarbonate and acetylcyclohexylsulfonyl peroxide and α, α′-azobisisobutyronitrile and α, α′-azobis2, An azo compound such as 4-dimethylvaleronitrile is used, and these are used alone or in combination of two or more. Examples of the water-soluble initiator include ammonium persulfate, potassium persulfate, hydrogen peroxide and the like, which are appropriately selected according to the polymerization method.

The suspending agent used in the suspension polymerization in the present invention may be a known suspending agent, for example, partially saponified polyvinyl alcohol, vinyl acetate-maleic anhydride copolymer, styrene-maleic anhydride copolymer, Examples thereof include polyvinylpyrrolidone, gelatin, starch, methylcellulose, and hydroxypropylcellulose, and these are used alone or in combination of two or more. The emulsifier used in microsuspension polymerization or emulsion polymerization may be a known emulsifier, for example, anionic surfactants such as sodium alkyl sulfate, sodium alkylbenzene sulfonate, sodium α-olefin sulfonate, and sodium fatty acid, and polyoxygen. Nonionic surfactants such as ethylene alkyl ether, polyoxyethylene alkyl phenol ether, (polyoxy) sorbitan fatty acid ester and the like can be mentioned, and these can be used alone or in combination of two or more. In the present invention, a molecular weight modifier can be used if necessary. Further, the polymerization initiator, suspending agent, emulsifier, molecular weight modifier and the like used in the polymerization reaction may be added to the polymerization reaction system all at once, or may be added separately during the polymerization reaction. The polymerization reaction temperature in the present invention is usually from 40 to 75 ° C, but is not particularly limited.

[0012]

The present invention will now be described in more detail with reference to Examples and Comparative Examples, but these are not intended to limit the present invention. In the following, the physical properties were evaluated according to the following methods; Particle size distribution: The sieve shaking method was used. Bulk specific gravity: According to JIS K6721. Porosity: Using a mercury intrusion porosimeter (model 5-7118) manufactured by AMINCO USA, the absolute pressure is 31 to
P between 1011 psi (0.17-5.8 μm diameter)
The porosity was determined by measuring the volume of mercury injected per 100 g of VC. Fish Eye: PVC 100 parts by weight, plasticizer PN2
50 [manufactured by Adeka Argus Co .; (adipic acid-based polyester; molecular weight: about 2,000)] 45 parts by weight, tribasic lead sulfate 3 parts by weight, stearic acid 0.5 parts by weight, titanium dioxide 0.4 parts by weight, and carbon black 0 2 parts by weight and allowed to stand for at least 3 hours, then kneaded with an 8-inch roll at 150 ° C. (sheet thickness: 0.2 mm), 5 minutes, 7 minutes, 9
The sheet was cut out at each minute, and the result was indicated by the number of transparent particles in the sheet 5 cm × 5 cm. Initial colorability: PVC 100 parts by weight, tin stabilizer TVS #
N-2000-C (manufactured by Nitto Kasei Co., Ltd.) 2 parts by weight and lubricant VLTN-4 (manufactured by Kawaken Fine Chemical Co., Ltd.)
After mixing 0.5 parts by weight, 165 ° C. with an 8-inch roll
The mixture was kneaded for 5 minutes to form a sheet having a thickness of 1 mm, and a 5 mm-thick press plate (pressing condition: 170 ° C. for 15 minutes) was prepared from the sheet, and the initial coloring property was evaluated. Thermal stability: A sheet similar to that prepared for the evaluation of the initial coloring property was prepared, placed in a gear oven at 200 ° C., taken out every 15 minutes, and the time until blackening was measured.

Example 1 A polymerization machine 1 having an internal volume of 1.7 m ³ provided with a reflux condenser 2 having a heat transfer area of 5 m ² as shown in FIG. 1 was charged with 120 parts by weight (660 kg) of deionized water and partially saponified polyvinyl. Alcohol 0.0
7 parts by weight were dissolved and charged, and 0.015 parts by weight of t-butyl peroxyneodecanate and 3,3 as a polymerization initiator were added.
5,5-trimethylhexanoyl peroxide 0.0
After adding 2 parts by weight, the inside of the polymerization machine was degassed, and 100 parts by weight (550 kg) of the purified vinyl chloride monomer was charged. The temperature was immediately raised to start the polymerization at a polymerization temperature of 67.5 ° C., and when the polymerization conversion reached 3%, the reflux condenser was operated. The polymerization reaction proceeds, and the pressure inside the polymerization machine becomes a steady pressure (1
When the cooling water inlet valve of the reflux condenser is fully opened at the time when the pressure falls by 0.5 kg / cm ² from 0.5 kg / cm ² G), the reflux condenser is adjusted while controlling the supply rate so that the resin in the polymerization reaction solution is not entrained. To the unreacted monomer, and the liquefied monomer is collected in the recovery tank 3
Led to. After recovering the unpolymerized monomer by this method until the pressure in the polymerization machine reaches 6 kg / cm ² G, the recovery method is switched to a method of recovering the vaporized unpolymerized monomer to the gas holder, and the resin is not accompanied. The recovery was performed while adjusting the recovery speed until the pressure in the polymerization machine became normal pressure. At this time, the time required for the recovery was a total of 20 minutes.

Example 2 Recovery was carried out in the same manner as in Example 1 except that the liquefied monomer was recovered in a recovery tank until the pressure in the can of the polymerization machine reached 4 kg / cm ² G. At this time, the time required for the collection was 30 minutes in total.

Example 3 Purified monomer 8 was used as a vinyl chloride monomer for polymerization.
P was prepared in the same manner as in Example 1 except that 5 parts by weight and 15 parts by weight of the monomer recovered in the recovery tank in Examples 1 and 2 were used.
VC was obtained.

Comparative Example 1 Polymerization was carried out in the same manner as in Example 1, and the unpolymerized monomer was vaporized over the entire period from the time when the pressure in the polymerization machine dropped from the steady pressure by 0.5 kg / cm ² to normal pressure. And collected in a gas holder. The required collection time at this time was 45 minutes.
Table 1 shows the physical property evaluation results of the PVCs obtained in Example 3 and Comparative Example 1. From Table 1, the physical properties of the PVC of Example 3 in which the unpolymerized monomer recovered in the liquefied state was used as a monomer for polymerization preparation without purification was not inferior to the physical properties of the PVC of Comparative Example 1. You can see that.

[0017]

[Table 1]

[0018]

According to the present invention, the time required for recovering the unpolymerized monomer can be greatly reduced, so that the polymerization productivity can be greatly improved. In addition, the liquefied unpolymerized monomer recovered according to the present invention can be used without purification as a monomer for polymerization preparation, and thus the present invention is also advantageous in terms of cost.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing one example of a polymerization apparatus used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Polymerizer 2 Reflux condenser 3 Recovery tank 4 Pump 5 Vaporized unpolymerized monomer recovery line

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C08F 6/10 C08F 14/06

Claims (3)

(57) [Claims] In a polymerization of a vinyl chloride monomer alone or a mixture of another monomer copolymerizable therewith with a vinyl chloride monomer using a polymerization machine provided with a reflux condenser outside the apparatus, the polymerization is carried out. When recovering the unpolymerized monomer which has been completed, the liquefied unpolymerized monomer refluxed from the reflux condenser is recovered in a recovery tank attached outside the polymerization machine. Production method. 2. The method according to claim 1, wherein the vaporized unpolymerized monomer is collected in a gas holder provided outside the polymerization machine at an arbitrary time after the start of the recovery of the liquefied unpolymerized monomer. Item 10. The production method according to Item 1. 3. The process according to claim 1, wherein the liquefied unpolymerized monomer recovered in the recovery tank is used as a monomer for polymerization without purification.