JPH08127620A - Method for producing vinyl chloride polymer - Google Patents

Abstract

PURPOSE: To obtain a vinyl chloride-based (co)polymer usable as for food containers and packagings with good productivity without deteriorating electrical insulating properties by adding a specific defoaming agent to a vinyl chloride- based (co)polymer slurry and then feeding the resultant slurry to a monomer stripping column. CONSTITUTION: The suspension (co)polymerization of (A) (i) vinyl chloride or (ii) a mixture of the component (i) with a monomer copolymerizable with the component (i) is carried out in the presence of (B) an oil-soluble polymerization initiator and (C) a dispersion stabilizer in an aqueous medium. (D) A sorbitan ester of a fatty acid (e.g. sorbitan monolaurate) or (E) a glycerol ester of a fatty acid (e.g. glycerol monooleate) or both are then added to the resultant vinyl chloride-based (co)polymer slurry after the (co)polymerization and the obtained slurry is then fed to a monomer stripping column to afford the objective (co)polymer.

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 polymer, and more particularly to a method for continuously removing unreacted vinyl chloride monomer from a vinyl chloride polymer slurry after polymerization. The present invention relates to a method for producing a vinyl chloride-based polymer that can remove unreacted vinyl chloride-based monomers without lowering quality and productivity and can be used for wire coating, food container packaging, etc. is there.

[0002]

2. Description of the Related Art Conventionally, in the step of continuously removing or recovering unreacted vinyl chloride monomer from a vinyl chloride polymer slurry, JP-A-54-8693 and JP-A-56-22305 are used. In the publication, the slurry to be treated is introduced onto the perforated plate trays of the processing tower in which the perforated plate trays having the groove-shaped processing passages are divided by partition walls, and steam is injected from below through the pores of the perforated plate. A processing method to do so has been proposed. In this method, the vinyl chloride polymer slurry to be treated on the perforated plate tray is foamed by introducing (injecting) water vapor from below. For this reason, as a method for suppressing foaming, water vapor is jetted to the liquid surface from another jet nozzle installed above the liquid surface of the slurry in JP-A-6-107723, and hot water is jetted from the hot water jet ring to the lower surface of the shelf and the inner wall of the apparatus. Has been proposed.

Further, JP-A-53-114891 proposes the use of a polyether antifoaming agent as a means for suppressing foaming during suspension polymerization of vinyl chloride.

[0004]

In the above-mentioned methods, when applied to a method for producing a porous vinyl chloride polymer having improved workability in recent years and having less fish eyes, a plate made of a perforated plate is used. It is not possible to suppress foaming from the above treated vinyl chloride polymer slurry, and the vinyl chloride resin particles attached to the inner wall of the processing device along with the generated bubbles are exposed to high temperature steam for a long time and deteriorate, which Since it peels off from the inner wall and mixes into the vinyl chloride polymer slurry to cause foreign matter, the slurry supply amount must be reduced to operate, and the throughput per unit time is reduced to produce the product. It has caused a decline in sex.

Further, in the method using a polyether type antifoaming agent, it was not possible to suppress foaming in the monomer stripping tower. In addition, when these defoaming agents are applied to the process of continuously removing unreacted vinyl chloride-based monomer from the vinyl chloride-based polymer slurry after polymerization, the electrical insulation of the obtained product is lowered and the electric wire It could not be used for coating purposes. Furthermore, these antifoaming agents cannot be used for food container packaging because they do not meet the voluntary regulation standard (hereinafter referred to as PL standard) regarding vinyl chloride resin food containers and packaging (created by the PVC Food Sanitation Council). Is.

Therefore, an object of the present invention is to produce unreacted vinyl chloride-based polymer slurry in the step of producing a vinyl chloride-based polymer which is porous and has high plasticizer absorbency and good fisheye characteristics. In the step of continuously removing or recovering vinyl chloride-based monomer, suppressing foaming from the vinyl chloride-based polymer slurry to be treated, and not lowering the electrical insulation of the product (vinyl chloride resin) after drying, Another object of the present invention is to provide a method for producing a vinyl chloride polymer that can be used for food container packaging and the like.

[0007]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have carried out suspension polymerization in an aqueous medium to produce a vinyl chloride polymer (hereinafter referred to as PVC). In the method described above, by adding a specific defoaming agent to the vinyl chloride polymer slurry after polymerization and then supplying it to the monomer stripping tower, it is possible to obtain high-quality PVC without lowering productivity. The inventors have found the present invention and completed the present invention.

That is, the present invention is a method for producing a vinyl chloride polymer by carrying out suspension polymerization of a vinyl chloride monomer in an aqueous medium in the presence of an oil-soluble polymerization initiator and a dispersion stabilizer. The present invention relates to a method for producing a vinyl chloride polymer, which comprises adding a sorbitan fatty acid ester and / or a glycerin fatty acid ester to the vinyl chloride polymer slurry in (1) and then supplying the resulting mixture to a monomer stripping column.

The present invention will be described in detail below.

The vinyl chloride-based monomer used in the present invention includes the vinyl chloride monomer itself as described above and a mixture of copolymerizable monomers mainly containing the vinyl chloride monomer. Be done. Examples of the monomer copolymerizable with the vinyl chloride monomer include olefins such as ethylene and propylene, vinyl esters such as vinyl acetate and vinyl stearate, vinyl ethers such as ethyl vinyl ether and cetyl vinyl ether, and acryl. Examples thereof include acid esters, esters such as maleic acid and fumaric acid, or anhydrides thereof, aromatic vinyl compounds such as styrene, and acrylonitrile. The copolymerizable monomer can be used usually in a proportion of 20% by weight or less based on the vinyl chloride monomer.

The dispersion stabilizer used in the present invention may be a dispersion stabilizer conventionally known as a dispersion stabilizer, but is vinyl chloride which is porous and has a high plasticizer absorbability and good fish eye characteristics. In order to obtain a system polymer, it is usually preferable to use the following (A) and (B) together as a dispersant.

(A) One or more partially saponified polyvinyl alcohol (hereinafter referred to as PVA) having a saponification degree of 70 to 90 mol% and an average degree of polymerization of 1500 to 3000 and / or a methoxy substitution degree of 26 to 30% by weight, Hydroxypropyl methylcellulose having a hydroxypropoxy substitution degree of 4 to 15% by weight and a 2% by weight aqueous solution thereof having a viscosity at 20 ° C. of 5 to 4000 cps.

(B) One or more types of PVA having a saponification degree of 60 mol% or less and an average degree of polymerization of 100 to 1000.

Examples of the oil-soluble polymerization initiator used in the present invention include peroxycarbonate compounds such as diisopropylperoxydicarbonate, di-2-ethylhexylperoxydicarbonate and diethoxyethylperoxydicarbonate; t-butylperoxide. Peroxyester compounds such as oxyneodecanate and α-cumylperoxyneodecanate; peroxides such as acetylcyclohexylsulfonyl peroxide; azobis-2,
Examples thereof include azo compounds such as 4-dimethylvaleronitrile and azobis- (4-methoxy-2,4-dimethylvaleronitrile), hydrogen peroxide and the like. These can be used alone or in combination of two or more.

The method of polymerizing PVC in the present invention is not particularly limited and may be carried out under the conditions of known suspension polymerization. For example, the amount of the aqueous medium, the amount of the polymerization initiator, the polymerization temperature, and the like used per vinyl chloride-based monomer may be in the conventionally adopted range. Further, if necessary, a pH adjusting agent, a polymerization degree adjusting agent and the like may be used as long as they do not affect the effects of the present invention.

As the antifoaming agent used in the present invention, sorbitan fatty acid ester and glycerin fatty acid ester are used. Examples of the sorbitan fatty acid ester antifoaming agent include sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, sorbitan trioleate, and the like, and glycerin fatty acid ester antifoaming agent. Examples of the glycerin monooleate, glycerin monostearate, glycerin monolaurate, glycerin monocaprate, glycerin tricaplate, glycerin tripalmitate, glycerin dioleate, glycerin trioleate, glycerin distearate, glycerin tristearate, diester Examples thereof include glycerin stearate, diglycerin oleate, diglycerin laurate and the like. These antifoaming agents can be used alone or in combination of two or more. These sorbitan fatty acid ester and glycerin fatty acid ester are in conformity with the positive list of the PL standard, and even if they are used as an additive of vinyl chloride resin for applications such as food container packaging, they are components with no safety and health problems. The amount of the defoaming agent added is not particularly limited, but if it is small, the defoaming effect is weak, and if it is large, the quality is greatly affected. Therefore, it is preferable to use it in the range of 1 ppm to 1000 ppm per unit slurry.

The defoaming agent may be added at any time after the completion of the polymerization, for example, a polymerization can, a blowdown tank,
Examples include stages before feeding to an intermediate slurry tank or a monomer stripping column. The defoaming effect in the monomer stripping tower cannot be obtained by adding the defoaming agent at the time of charging each material before the start of the polymerization or during the polymerization.

The defoaming agent may be added as a stock solution, a solution of a solvent or water, or a dispersion, by batch addition to a polymerization vessel or a blowdown tank, or continuous addition to an intermediate pipe before feeding the monomer stripping tower. It may be a method.

The operating conditions of the monomer stripping tower are as follows:
It is not particularly limited as long as it is a condition sufficient to remove the residual monomer from the treated vinyl chloride polymer slurry, but the temperature of the treated vinyl chloride polymer slurry in the tower is usually such that removal of the residual monomer is efficient and 60 to 130 from the point that problems with the quality of the obtained vinyl chloride-based polymer are unlikely to occur.
℃ Preferably, the amount of water vapor is introduced from below into the column removal of residual monomers efficiently, vinyl treated chloride from the viewpoint of excellent economic standpoint polymer slurry 1 m ³ per 1 to 1
00 Kg / h is preferable.

[0020]

EXAMPLES The production method of the present invention will be described below based on Examples and Comparative Examples, but the present invention is not limited thereto.

The evaluations in Examples and Comparative Examples were measured by the following methods.

(Fish Eye) Vinyl Chloride Polymer 1
00 parts by weight, Trioctyl trimellitate 60 parts by weight,
After mixing 2 parts by weight of stabilizer and a small amount of ultramarine blue, 150 ° C
50 cm ^{2 of the} sheet obtained by kneading with a roll for 7 minutes
The number of fish eyes found inside was measured.

(Volume Specific Resistivity) Vinyl Chloride Polymer 1
A sheet obtained by mixing 00 parts by weight, 50 parts by weight of di-2-ethylhexyl phthalate and 4 parts by weight of a stabilizer and then kneading with a roll at 150 ° C. for 7 minutes is further heated at 170 ° C.
It was pressed for a minute to obtain a test piece of 70 mmφ. The measurement is a super insulation resistance tester (product of Advantest Corporation, trade name T
R8601) was used.

Example 1 1100 kg of deionized water was charged into a stainless steel polymerization vessel equipped with a stirrer having an internal volume of 2 cubic meters and a jacket, and then saponification degree was 80 mol% and average polymerization degree was 2600.
630 g of PVA was charged. Then, it was deaerated with a vacuum pump until the internal pressure of the polymerization container reached 60 Torr. After degassing, charge 900 kg of vinyl chloride monomer into a polymerization vessel,
Then PVA with a saponification degree of 45 mol% and an average degree of polymerization of 300
A solution prepared by dissolving 450 g of a solvent in which the weight ratio of water: methanol was 1: 1 was charged into a polymerization vessel. Next, as a polymerization initiator, t-butyl peroxyneodecanate 36 was used.
After charging 0 g, stirring was started, the temperature was further increased, and polymerization was carried out at a temperature of 57 ° C. 4 to raise the temperature to the specified polymerization temperature
It took 0 minutes. The reaction was stopped when the internal pressure dropped to 6.0 kg / cm ² G, and then unreacted vinyl chloride monomer was recovered in the polymerization vessel, and then sorbitan sesquiolate 5 was added.
0 g was added to obtain a vinyl chloride polymer slurry to be treated.

Next, the inner diameter is 700 mmφ and the tower length is 5,000.
Saturated steam is blown from the bottom of a stainless steel stripping tower (sieve tray, 5 stages) with a 0 mm observation window at 30 kg / h per 1 m ^{3 of} vinyl chloride polymer slurry to be treated, and vinyl chloride at 90 ° C. is treated from the top of the tower. The polymer slurry was fed. The amount of slurry supply was increased while visually confirming the foaming condition from the top and bottom viewing windows of the stripping tower.
^The maximum supply amount was 11.7 m ³ / h per ² times, and the residence time of the untreated vinyl chloride polymer slurry in the column was 7 minutes. The vinyl chloride polymer slurry after demonomerization was dried by a conventional method to obtain a product.

The evaluation results of the obtained vinyl chloride polymer are shown in Table 1.

Here, foaming in the monomer stripping tower was suppressed, the amount of slurry supplied could be increased, and the amount of slurry processed per unit time could be increased. Moreover, the obtained vinyl chloride polymer did not deteriorate the electrical insulation. The defoamer used conforms to the PL standard and can be used for applications such as food container packaging.

Example 2 A vinyl chloride polymer was produced in the same manner as in Example 1 except that 50 g of sorbitan monostearate was added to the vinyl chloride polymer slurry by an acetone solution.

The maximum amount of slurry to be supplied to the monomer stripping column, which has no problem in foaming, is 1 m ^{2 based on the} area of the perforated plate.
11.2 m ³ / h per hour, and the residence time of the untreated vinyl chloride polymer slurry in the tower was 7 minutes.

Table 1 shows the evaluation results of the obtained vinyl chloride polymer.

Here, foaming in the monomer stripping tower was suppressed, the amount of slurry supplied could be increased, and the amount of slurry processed per unit time could be increased. Moreover, the obtained vinyl chloride polymer did not deteriorate the electrical insulation. The defoamer used conforms to the PL standard and can be used for applications such as food container packaging.

Example 3 A vinyl chloride polymer was produced in the same manner as in Example 1 except that 50 g of glycerin monooleate was added to the vinyl chloride polymer slurry as an acetone solution.

The maximum amount of slurry to be supplied to the monomer stripping column, which has no problem in foaming, is 1 m ^{2 based on the} area of the perforated plate.
Per 10.9 m ³ / h, and the residence time of the untreated vinyl chloride polymer slurry in the tower was 7 minutes.

Table 1 shows the evaluation results of the obtained vinyl chloride polymer.

Here, foaming in the monomer stripping tower was suppressed, the amount of slurry supplied could be increased, and the amount of slurry processed per unit time could be increased. Moreover, the obtained vinyl chloride polymer did not deteriorate the electrical insulation. The defoamer used conforms to the PL standard and can be used for applications such as food container packaging.

Example 4 A vinyl chloride polymer was produced in the same manner as in Example 1 except that 40 g of sorbitan monooleate and 40 g of glycerin distearelate were added to a vinyl chloride polymer slurry by an acetone solution.

The maximum amount of slurry to be supplied to the monomer stripping column which has no problem in foaming is 1 m ^{2 based on the} area of the perforated plate.
11.2 m ³ / h per hour, and the residence time of the untreated vinyl chloride polymer slurry in the tower was 7 minutes.

The evaluation results of the obtained vinyl chloride polymer are shown in Table 2.

Here, foaming in the monomer stripping tower was suppressed, the amount of slurry supplied could be increased, and the amount of slurry processed per unit time could be increased. Moreover, the obtained vinyl chloride polymer did not deteriorate the electrical insulation. The defoamer used conforms to the PL standard and can be used for applications such as food container packaging.

Example 5 A vinyl chloride polymer was produced in the same manner as in Example 1 except that 30 g of sorbitan trioleate and 30 g of sorbitan tristearearate were added to a vinyl chloride polymer slurry by an acetone solution.

The maximum amount of slurry to be supplied to the monomer stripping column, which has no problem in foaming, is 1 m ^{2 based on the} area of the perforated plate.
Per 10.9 m ³ / h, and the residence time of the untreated vinyl chloride polymer slurry in the tower was 7 minutes.

The evaluation results of the obtained vinyl chloride polymer are shown in Table 2.

Here, foaming in the monomer stripping tower was suppressed, the amount of slurry supplied could be increased, and the amount of slurry processed per unit time could be increased. Moreover, the obtained vinyl chloride polymer did not deteriorate the electrical insulation. The defoamer used conforms to the PL standard and can be used for applications such as food container packaging.

Comparative Example 1 A vinyl chloride polymer was produced in the same manner as in Example 1 except that the antifoaming agent was not added to the vinyl chloride polymer slurry.

The maximum amount of slurry to be supplied to the monomer stripping column which has no problem in foaming is 1 m ^{2 based on the} area of the perforated plate.
It was 6.5 m ³ / h, and the residence time of the untreated vinyl chloride polymer slurry in the column was 12 minutes.

Table 3 shows the evaluation results of the obtained vinyl chloride polymer.

In this case, since the foaming in the monomer stripping column is severe and the slurry supply amount cannot be increased, the production amount per unit time was low.

Comparative Example 2 A vinyl chloride polymer slurry was mixed with a polyether antifoaming agent (Daiichi Kogyo Seiyaku Co., Ltd., trade name Antifloss F-24).
4) A vinyl chloride polymer was produced in the same manner as in Example 1 except that 50 g was added.

The maximum amount of slurry to be supplied to the monomer stripping column, which has no problem in foaming, is 1 m ^{2 based on the} area of the perforated plate.
Per 11.7 m ³ / h, and the residence time of the untreated vinyl chloride polymer slurry in the tower was 7 minutes.

Table 3 shows the evaluation results of the obtained vinyl chloride polymer.

The obtained vinyl chloride polymer had a low specific volume resistivity and was not suitable for applications requiring electrical insulation.

Comparative Example 3 Same as Example 1 except that 50 g of a fatty acid WAX antifoaming agent (San Nopco Ltd., trade name Nopco JMY: content of polyether type component 40%) was added to a vinyl chloride polymer slurry. A vinyl chloride polymer was produced by the method described in 1.

The maximum amount of slurry to be supplied to the monomer stripping column, which has no problem in foaming, is 1 m ^{2 based on the} area of the perforated plate.
Per 10.9 m ³ / h, and the residence time of the untreated vinyl chloride polymer slurry in the tower was 7 minutes.

Table 3 shows the evaluation results of the obtained vinyl chloride polymer.

The obtained vinyl chloride polymer had a low volume resistivity and was not suitable for applications requiring electrical insulation.

Comparative Example 4 1100 kg of deionized water was charged into a stainless steel polymerization container equipped with a stirrer and a jacket having an internal volume of 2 cubic meters, and then saponification degree was 80 mol% and average polymerization degree was 2600.
630 g of PVA was charged. Then, it was deaerated with a vacuum pump until the internal pressure of the polymerization container reached 60 Torr. After degassing, charge 900 kg of vinyl chloride monomer into a polymerization vessel,
Then PVA with a saponification degree of 45 mol% and an average degree of polymerization of 300
A solution prepared by dissolving 450 g of a solvent in which the weight ratio of water: methanol was 1: 1 was charged into a polymerization vessel. Next, as a polymerization initiator, t-butyl peroxyneodecanate 36 was used.
0 g and 50 g of sorbitan sesquioleate as an antifoaming agent were charged, and then stirring was started to further raise the temperature to a temperature of 5
Polymerization was carried out at 7 ° C. It took 40 minutes to raise the temperature to the predetermined polymerization temperature. When the internal pressure dropped to 6.0 kg / cm ² G, the reaction was stopped, and then unreacted vinyl chloride monomer was recovered in the polymerization vessel to obtain a vinyl chloride polymer slurry to be treated. Regarding the subsequent operation, the maximum slurry supply amount to the monomer stripping column having no problem in foaming according to Example 1 was 6.2 m ³ / m ² per 1 m ^{2 on} a perforated plate area basis.
and the residence time of the untreated vinyl chloride polymer slurry in the tower was 12 minutes.

Table 3 shows the evaluation results of the obtained vinyl chloride polymer.

In this case, since the foaming in the monomer stripping tower is severe and the slurry supply amount cannot be increased, the production amount per unit time is low.

[0059]

[Table 1]

[0060]

[Table 2]

[0061]

[Table 3]

[0062]

Industrial Applicability According to the method of the present invention, a PVC which can be used for food container packaging and the like without lowering the electrical insulation property can be obtained with high productivity, and the industrial value of the present invention is extremely large. .

Claims (1)

[Claims] 1. A mixture of vinyl chloride or a monomer copolymerizable with vinyl chloride (hereinafter referred to as vinyl chloride monomer).
In the method for producing a vinyl chloride polymer by carrying out suspension polymerization in an aqueous medium in the presence of an oil-soluble polymerization initiator and a dispersion stabilizer, sorbitan fatty acid ester and / or a vinyl chloride polymer slurry after polymerization is prepared. A method for producing a vinyl chloride polymer, which comprises adding a glycerin fatty acid ester and then supplying it to a monomer stripping column.