JP2000212206A - Production of vinyl chloride polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a vinyl chloride polymer able to give a molding with reduced initial coloration, excellent in productivity, nonstickiness to a calender roll, and able to give a molding with few fish eyes by performing high-speed suspension polymerization in a large polymerizer under conditions in which a specified dispersion stabilizer is used and the ratio of heat removal with a reflux condenser is a specified or larger one. SOLUTION: The polymerization is performed within 6 hr in a polymerizer with an internal volume of 100 m3 or above under conditions in which the dispersion stabilizer used comprises 0.02-0.15 pt.wt., per 100 pts.wt. monomer, partially saponified PVA having a degree of saponification of 75-90 mol% and an average degree of polymerization of 1,500-3,000 and 0.005-0.05 pt.wt., per 100 pts.wt. monomer, hydroxypropylcellulose having a degree of hydroxypropylation of 5-25% and a viscosity of 10-80 cP (as measured in a 2 wt.% aqueous solution at 20 deg.C) and/or partially saponified PVA having a degree of saponification of 25-65 mol% and an average degree of polymerization of 200-1,000 and has a reduced yellowness YI' of 30 or below, and the rate of heat removal with a reflux condenser is 30% or above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a vinyl chloride polymer. More specifically, the present invention relates to a method for producing a vinyl chloride-based polymer which is excellent in the initial coloring property of a molded article, and which is excellent in productivity, roll adhesiveness in calender molding, fisheye properties of the molded article, and the like.

[0002]

2. Description of the Related Art Vinyl chloride polymers are used in various fields because of their excellent physical and mechanical properties. Extrusion molding, calender molding, injection molding and the like are generally used as a molding method of the vinyl chloride polymer. Among these, in calender molding applications, when forming sheets or films, depending on the compatibility of the vinyl chloride polymer and the compounding agent, stickiness with the roll may occur, resulting in uneven thickness or winding around the roll. There were problems such as a decrease in performance. Further, even if the vinyl chloride polymer is less likely to cause roll adhesion, a fisheye or poor color tone which impairs the appearance of the molded product is not suitable for calendar applications.

Further, in recent years, there has been a strong demand from processing users for a slightly inexpensive vinyl chloride polymer in order to reduce raw material costs, and a technology for producing an inexpensive vinyl chloride polymer while maintaining quality has been keenly desired. ing. For these reasons, calender molding users have been demanding the development of a vinyl chloride polymer that is inexpensive, has little roll stickiness, has good fisheye of the molded product, and has good initial coloring properties.

On the other hand, in the vinyl chloride polymer production industry, in order to provide a cheaper vinyl chloride polymer, a conventional low-capacity polymerizer is changed from a conventional low-capacity polymerizer to a large-sized polymerizer having a productivity of 100 m ³ or more. Switching is being considered. If the polymerization time is shortened by increasing the amount of initiator to increase production efficiency in such a large-scale polymerization reactor, the cooling capacity cannot catch up with the conventional jacket-type heat removal alone. Is used to remove excess heat of reaction.

[0005] However, when the heat removal amount of the reflux condenser is increased in order to enhance the production efficiency, a foaming phenomenon in which the polymer particles float as a cream layer above the suspension with the progress of polymerization is observed. In particular, the heat removal rate of the reflux condenser should be 30
% Or more, this foaming phenomenon becomes remarkable, and a large amount of scale adheres to the inside of the reflux condenser and the conduit, thereby reducing the heat removal capability of the reflux condenser and the quality of the molded product. And worsened the fisheye of the fish.

When a vinyl chloride polymer is produced by suspension polymerization, the dispersion stabilizer is incorporated into the polymer particles by grafting or adsorbing on the particle surface of the vinyl chloride polymer. Depending on the method of use of the agent, the initial coloring property of a vinyl chloride polymer may be greatly impaired. As described above, when high-speed polymerization is performed by using a large-sized polymerization vessel with the heat removal rate of the reflux condenser being 30% or more as described above, it is necessary to increase the amount of the polymerization initiator or to use a polymerization initiator having high activity. This is particularly noticeable. In addition, in order to achieve such high productivity, there is a certain restriction on the type and amount of the dispersion stabilizer, so that it is more difficult to solve the problem of the deterioration of the initial coloring property while maintaining the performance balance. It is.

In recent years, a closed mode polymerization method has been widely used for the purpose of further increasing productivity and reducing the burden on the environment. The polymerization in the closed mode refers to a polymerization method in which the manhole of the polymerization vessel is opened and the next preparation is performed without removing the scale in the polymerization vessel. That is, after the polymerization reaction is completed and the slurry is discharged, the vinyl chloride monomer remains in the gas phase inside the polymerization vessel without releasing to the atmosphere, that is, opening the manhole of the polymerization vessel, air, nitrogen, etc. Means performing the next polymerization without replacing the inside of the system with an inert gas. Without opening the inside of the polymerization vessel, the remaining polymer in the polymerization vessel can be removed only by simple washing with water to carry out the next polymerization operation, thereby avoiding the release of vinyl chloride monomer to the atmosphere and / or removing the vinyl chloride monomer in the apparatus. The operation of collecting can be streamlined,
Thereby, vinyl chloride polymerization can be rationalized. However, when the closed mode polymerization is employed, there is a problem that the initial coloring property of the molded article is more likely to be deteriorated. Closed mode polymerizations generally apply a scale anti-adhesion agent at the end of each batch. In particular,
After extracting the vinyl chloride polymer slurry from the polymerization vessel,
A step of applying a scale anti-adhesion agent, then washing with water to remove excess scale anti-adhesion agent, and then charging a monomer is performed. However, residual monomers and the like are adhered to the inner wall of the polymerization vessel after the slurry is extracted, and the anti-scale adhesion agent is often not applied well. Although the cause is not always clear, it is considered to be due to cissing due to residual monomers and the like. For this reason, the scale adhesion preventing agent is easily detached from the inner wall of the polymerization vessel, and mixes with the vinyl chloride polymer to cause deterioration of the initial coloring property.

As described above, it is difficult to obtain good initial coloring properties by the polymerization method for realizing high productivity, and it is also difficult to obtain other properties such as roll adhesion in calendering and fish eye properties of molded articles. It has been particularly difficult to achieve excellent initial coloring characteristics while maintaining good characteristics.

[0009]

SUMMARY OF THE INVENTION In view of the above, the present invention relates to productivity, roll adhesion in calendering, fisheye characteristics of molded products, and initial coloring of molded products. It is an object of the present invention to provide a method for producing a vinyl chloride-based polymer which satisfies a high level requirement as currently required.

In particular, a polymerization vessel having an internal volume of 100 m ³ or more provided with a stirrer, a jacket, and a reflux condenser as described above is used, and the amount of heat removed by the reflux condenser during polymerization is 30 to the total amount of heat removed. % Or more, and a specific problem under severe polymerization conditions such as a polymerization time of 6 hours or less, and further, a specific problem associated with the closed mode polymerization described above.

[0011]

Means for Solving the Problems The inventors of the present invention have made intensive studies in order to solve the above-mentioned problems, and are constituted as follows.

A polymerization vessel having an internal volume of 100 m ³ or more provided with a stirrer, a jacket and a reflux condenser is used. The amount of heat removed by the reflux condenser during polymerization is set to 30% or more of the total heat removal, and the polymerization time is reduced. When a vinyl chloride monomer is subjected to suspension polymerization in an aqueous medium in the presence of an oil-soluble polymerization initiator under a polymerization condition of 6 hours or less, (A) a saponification degree of 75 to 90 is used as a dispersion stabilizer. Mol%, average polymerization degree 1500
-3000 partially-saponified polyvinyl alcohol in an amount of 0.02-0.15 per 100 parts by weight of the vinyl chloride monomer.
Parts by weight (B) hydroxypropyl methylcellulose and / or saponification wherein the degree of methoxy substitution is 15 to 40% by weight, the degree of hydroxypropoxy substitution is 5 to 25% by weight, and the viscosity of the 2% by weight aqueous solution at 20 ° C. is 10 to 80 cps. Of partially saponified polyvinyl alcohol having a degree of polymerization of 25 to 65 mol% and an average degree of polymerization of 200 to 1000
Using 0.005 to 0.05 parts by weight to 00 parts by weight, the converted yellowness YI ′ defined by the following formula (1) is used.
Is 30 or less, the method for producing a vinyl chloride polymer. _{YI '= α A YI A +} α B YI B ... (1) ( wherein, alpha _A, alpha and _B are, dispersion stabilizer to the total dispersion stabilizer (A), represents the weight content of (B), YI _A ,
Each YI _B is defined dispersion stabilizer in JIS K-7105 (A), it represents the yellowness index YI value of (B). )

The method for producing a vinyl chloride polymer according to claim 1, wherein the converted yellowness YI 'is 20 or less.

When the total amount of the dispersion stabilizer (A) and the dispersion stabilizer (B) is 0.0% with respect to 100 parts by weight of the vinyl chloride monomer.
The method for producing a vinyl chloride-based polymer according to or above, wherein the amount is 3 to 0.2 parts by weight, and the weight ratio of (A) / (B) is 0.5 to 4.

The method for producing a vinyl chloride polymer according to any one of claims 1 to 3, wherein the suspension polymerization is carried out in a closed mode after a scale adhesion inhibitor is applied to the inner wall of the polymerization vessel.

A lubricant consisting of at least one compound selected from the group consisting of polyolefins, paraffins and chlorinated hydrocarbons and having an average particle size of 300 μm or less is used in a slurry state at the beginning of polymerization, during polymerization, or after completion of polymerization. The method for producing a vinyl chloride polymer according to any one of claims 1 to 3, wherein 0.001 to 0.3 parts by weight of the vinyl chloride polymer is added to 100 parts by weight of the vinyl chloride monomer.

A vinyl chloride polymer produced by the method for producing a vinyl chloride polymer according to any one of the above.

According to the present invention described above, vinyl chloride exhibiting high-level properties in all of productivity, roll adhesiveness in calender molding, fisheye properties of molded articles, and initial coloring properties of molded articles. A polymer is obtained.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

The polymerization vessel used in the present invention is a stirred vessel.
100m with a machine, jacket and reflux condenser
^ThreeAbove, preferably 120m^ThreeAbove, more preferably 15
0m ^ThreeThe above is a polymerization vessel. Internal volume is 100m^ThreeLess than heavy
The heat sink can be removed by the usual external jacket cooling method.
And does not necessarily require a reflux condenser. Also, the contents
Product 100m^ThreeLess than the polymerization unit, the production per batch
Because of the small volume, it is necessary to have many
Need to be one. For this reason, the polymerization equipment becomes complicated and
There are cost issues such as increased capital investment. Also this
In a large-capacity polymerization reactor like this, the heat removal amount of the reflux condenser is increased.
If compared to conventional jacket type polymerization reactors,
Polymerization time can be shortened, which could not be achieved so far
High-speed, high-productivity polymerization is possible. Heat removal rate of reflux condenser
30% or more, preferably 40% or less of the total
It is more preferably at least 50%. Heat removal ratio is 30
%, Polymerization time cannot be reduced due to heat removal problems.
Therefore, the production efficiency is undesirably reduced. Return
If the heat removal ratio of the flow condenser is less than 30%, the foaming phenomenon is too large.
The present invention is not always necessary because it does not
do not do. On the other hand, if the heat removal ratio is 30% or more, the polymerization time
Can be shortened, especially by setting it to 40% or more.
Polymerization time can be greatly reduced, improving production efficiency
It is planned.

The dispersion stabilizer (A) used in the present invention has a degree of saponification of 75 to 90 mol%, preferably 75 mol%.
~ 88 mol%, more preferably 75 ~ 85 mol%, and the average degree of polymerization is 1500 ~ 3000, preferably 170
0 to 3000, more preferably 1700 to 2800, a partially saponified polyvinyl alcohol, and 0.02 to 0.15 parts by weight based on 100 parts by weight of the vinyl chloride monomer,
Preferably 0.02 to 0.13 parts by weight, more preferably 0.02 to 0.12 parts by weight.

Here, the saponification degree of the dispersion stabilizer (A) is 7
When the polymerization degree is less than 5 mol% or the average degree of polymerization is less than 1500, the polymerization stability is poor. When the heat removal rate of polymerization of the reflux condenser is 30% or more, the foaming phenomenon during the polymerization becomes particularly severe, so that the reflux There are problems such as increased scale adhesion to the condenser. Further, even in the forming process, roll adhesion on a calendar becomes remarkable, which is not preferable. On the other hand, when the degree of saponification is 90 mol% or the average degree of polymerization exceeds 3,000, it is not preferable because there are problems such as a broad particle size distribution of the obtained vinyl chloride-based polymer and deterioration of fish eyes. . In addition, the amount used is 0.02
If the amount is less than 0.1 part by weight, the polymerization stability is poor, and if the amount exceeds 0.15 part by weight, the obtained vinyl chloride polymer becomes finer, and not only becomes difficult to handle powder, but also the fish eye of the molded product becomes poor. It is not preferable because it deteriorates.

As the dispersion stabilizer (B) used in the present invention, hydroxypropyl methylcellulose and / or partially saponified polyvinyl alcohol is used. Hydroxypropyl methylcellulose has a degree of methoxy substitution of 15 to 40% by weight, preferably 20 to 35% by weight, more preferably 25 to 30% by weight, and a degree of hydroxypropoxy substitution of 5 to 25% by weight, preferably 5
-20% by weight, more preferably 5-15% by weight,
Further, the viscosity at 20 ° C. of the 2% by weight aqueous solution is 1%.
It is 0 to 80 cps, preferably 20 to 75 cps, more preferably 30 to 70 cps. The partially saponified polyvinyl alcohol has a degree of saponification of 25 to 65 mol%, preferably 28 to 55 mol%, more preferably 30 to 50 mol%, and an average degree of polymerization of 200 to 1000, preferably 200 to 900. And more preferably 200 to 800. The dispersion stabilizer (B) comprising these components is added in an amount of 0.005 to 0.0 with respect to 100 parts by weight of the vinyl chloride monomer.
5 parts by weight, preferably 0.01 to 0.045 parts by weight, more preferably 0.01 to 0.04 parts by weight.

Here, when the methoxy substitution degree, hydroxypropoxy substitution degree and aqueous solution viscosity of the hydroxypropylmethylcellulose of the dispersion stabilizer (B) are out of the above ranges, the polymerization stability is poor and the polymerization heat removal ratio of the reflux condenser is poor. 3
If it is 0% or more, the foaming phenomenon during polymerization becomes intense, causing problems such as increased scale adhesion to the reflux condenser. In addition, the fish eye of the molded product is also deteriorated. Further, the degree of saponification of the partially saponified polyvinyl alcohol of the dispersion stabilizer (B) is less than 25 mol%, or the average degree of polymerization is 2%.
If it is less than 00, the obtained particles are undesirably coarse and roll adhesion on a calendar becomes remarkable. On the other hand, if the degree of saponification exceeds 65 mol% or if the average degree of polymerization exceeds 1,000, fish eyes of the molded article deteriorate, which is not preferable. In addition, the amount used is 0.
When the amount is less than 005 parts by weight, there is no effect of improving fish eyes. When the amount exceeds 0.05 parts by weight, when the polymerization heat removal ratio of the reflux condenser is set to 30% or more, the foaming phenomenon particularly during polymerization becomes severe, It is not preferable because scale adhesion to the condenser increases. Further, since the obtained vinyl chloride polymer is also finely divided, powder handling becomes difficult, which is not preferable.

The total amount of the dispersion stabilizer (A) and the dispersion stabilizer (B) used in the present invention is 100% of the vinyl chloride monomer.
0.03 to 0.2 part by weight, preferably 0.04 to 0.18 part by weight, more preferably 0.04 to 0.1 part by weight based on part by weight.
0.15 parts by weight are used. Further, the weight ratio of the dispersion stabilizer (A) / (B) used in the present invention is 0.5-4, preferably 0.6-3.5, more preferably 0.6-3.

Here, the sum of (A) and (B) is 0.03
When the amount is less than the weight part, the polymerization stability is deteriorated and the particles may be coarsened. On the other hand, when the amount exceeds 0.2 parts by weight, when the heat removal rate of polymerization of the reflux condenser is set to 30% or more, foaming to the reflux condenser during polymerization is particularly severe, and scale adheres to the reflux condenser. In addition, the fish eye of the molded product may be deteriorated. Further, since the obtained vinyl chloride polymer is also finely divided, powder handling may be difficult. or,
When the weight ratio of (A) / (B) is less than 0.5, when the heat removal ratio of polymerization of the reflux condenser is set to 30% or more, the foaming phenomenon particularly during polymerization is reduced and the polymerization stability is reduced. There is. Further, the particles may become coarse. Also, (A) /
When the weight ratio of (B) exceeds 4, the fish eye of the molded article may be deteriorated.

The converted stable yellowness YI ′ used in the present invention is defined by the following formula, and its value is 30 or less. _{YI '= α A YI A +} α B YI B (1) ( wherein, α _A, α _B of the dispersion stabilizer to the total dispersion stabilizer (A), represents the weight content of (B), YI _A is JIS
It shows the yellowness YI value of the dispersion stabilizers (A) and (B) defined in K-7105. If YI ′ exceeds 30, the initial coloring property of the resulting vinyl chloride polymer deteriorates, which is not preferred. In particular, when used for applications requiring transparency, a higher level of initial coloring property is required. Therefore, YI ′ is preferably 20 or less, more preferably 1 or less.
0 or less.

In order to lower the YI 'value of the dispersion stabilizer, it is effective to lower the yellowness of the partially saponified polyvinyl alcohol. As a method for this, for example, a method of dissolving polyvinyl alcohol in water and then performing filtration using activated carbon or the like can be used.
Also, after acetylation of the hydroxyl group of polyvinyl alcohol, hydrogen is blown in an organic solvent such as alcohol, hydrogenation of the double bond portion is performed, and then hydrolysis is performed to generate a hydroxyl group.
In some cases, this method is effective. Further, a method of removing a low molecular weight portion of polyvinyl alcohol may be employed. Each of the above methods is not necessarily effective for all types of polyvinyl alcohol, and it is appropriate to select an optimal method according to the type of polyvinyl alcohol.

In the present invention, in order to improve the vinyl chloride polymer so as to be suitable for calendering at a high temperature where further improvement in roll adhesion is required, a group consisting of polyolefin, paraffin, and chlorinated hydrocarbon is used. Has an average particle size of at least one compound selected from
It is preferable to add 0.001 to 0.3 parts by weight of a lubricant having a size of 00 μm or less based on 100 parts by weight of the vinyl chloride monomer at the beginning of polymerization, during polymerization, or after completion of polymerization. The average particle size of the lubricant is 300 μm or less, preferably 200 μm
m, more preferably 100 μm or less. 300
If it exceeds μm, there is a problem in the uniformity of dispersion of the lubricant particles,
This is not preferable because the effect of suppressing the occurrence of roll sticking on the calendar is greatly reduced. The lower limit of the particle size is not particularly limited, but is, for example, 0.1 μm or more. The amount of the lubricant added is preferably 0.002 to 0.2 parts by weight, more preferably 0.003 to 0.15 parts by weight.

Examples of the polyolefin used in the present invention include known polyolefins, for example, polyethylene wax, polypropylene wax, and the like. From the viewpoint of the effect of improving roll adhesiveness, those having a low molecular weight belonging to the category of wax are preferable, and particularly those having low molecular weight are preferable. Polyethylene wax is particularly preferred. As the paraffin and the chlorinated hydrocarbon, known paraffins and chlorinated hydrocarbons added to a vinyl chloride resin are used, and examples thereof include natural paraffin having a melting point of 50 ° C. or higher, 2-chloronaphthalene, and the like. .

The timing of adding the above lubricant is not particularly limited. For example, at the beginning of polymerization, during polymerization, in the state of slurry after recovery of unreacted vinyl chloride monomer, in the state of wet cake after dewatering the slurry, For example, when the powder is in a powder state after the wet cake is dried. Among these, especially when the lubricant is added at the beginning of polymerization, during the polymerization, or in the slurry state after the polymerization is completed, the effect of improving the roll adhesion is large, and the same effect of improving the roll adhesion can be obtained by adding a small amount compared with other addition times. Can be Therefore, when the above lubricant is added at this time, the amount of the
0.001 to 0.3 part by weight, preferably 0.002 to 0.15 part by weight, more preferably 0.001 part by weight with respect to part by weight.
A sufficient improvement effect can be obtained with 3 to 0.1 parts by weight.

Here, the initial stage of the polymerization in the present invention means from the time when the aqueous medium, the vinyl chloride-based monomer, etc. are charged to the polymerization vessel to before the polymerization is substantially started, that is, the polymerization conversion rate is less than 1% by weight. It means until the time. The term “during polymerization” refers to a period from a polymerization conversion of 1% by weight to a time before the unreacted vinyl chloride monomer at the time of completion of the polymerization is recovered. Furthermore, the state of the slurry state after the completion of the polymerization refers to a period from the time when the unreacted vinyl chloride monomer is recovered at the time when the polymerization is completed to the time when the discharged slurry is subjected to centrifugal dehydration.

The method of adding the lubricant used in the present invention is not particularly limited.
A method in which the lubricant is emulsified in water or dissolved in an organic solvent is added at once, dividedly added, continuously added, or sprayed.

In the present invention, a commonly used suspension polymerization method can be applied as it is, for example, specifically, the following method is used.

Deionized water, a dispersion stabilizer, and a polymerization initiator are charged into a pressure-resistant polymerization reactor provided with a stirrer, an outer jacket and a reflux condenser, and the pressure is reduced. Next, a vinyl chloride-based monomer is injected under pressure, and the polymerization is started by heating while stirring the inside of the polymerization vessel. The polymerization conditions at that time are, for example, a polymerization temperature of 20 to 90 ° C. and a polymerization time of 1 to 6 hours. After completion of the polymerization, the unreacted vinyl chloride-based monomer is recovered, and the slurry is taken out and dehydrated and dried to obtain a vinyl chloride-based polymer.

The polymerization initiator used in the present invention may be any one generally used as a polymerization initiator in a suspension polymerization method. Examples of the polymerization initiator include tert-butylperoxyneodecanoate and tert-hexylperoxyneo. Decanoate, tert-hexylperoxypivalate, tert-butylperoxypivalate, α-cumylperoxyneodecanoate, tert-hexylperoxyneohexanoate, α, α′-bis (neodecanoyl Peroxy) diisopropylbenzene, 1,
1,3,3-tetramethylbutyl peroxy neodecanoate, 1-cyclohexyl-1-methylethyl peroxy neodecanoate, tert-hexyl peroxyglycolate, 1,1-dimethyl-3-hydroxybutyl peroxy Perester compounds such as oxyneodecanoate; diisopropyl peroxydicarbonate, di-2
-Ethylhexyl peroxydicarbonate, di-2-
Percarbonate compounds such as ethoxyethylperoxydicarbonate and dimethoxyisopropylperoxydicarbonate; peroxide compounds such as benzoyl peroxide, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide and acetylcyclohexyl peroxide; 2,2 Examples include azo compounds such as' -azobisisobutyronitrile and 2,2'-azobis-2,4-dimethylvaleronitrile, which can be used alone or in combination of two or more.

In the present invention, when the present invention is carried out, a vinyl monomer copolymerizable with a vinyl chloride monomer or a polymer graft polymerizable with a vinyl chloride monomer is added as necessary. And may be polymerized.

In the present invention, the vinyl chloride monomer is
A vinyl chloride monomer or a mixture of a vinyl monomer and a vinyl monomer copolymerizable therewith.

Examples of the vinyl monomer copolymerizable with the vinyl chloride monomer include vinyl esters such as vinyl acetate, vinyl propionate, vinyl caproate, vinyl laurate and vinyl stearate; ethylene, propylene, Olefins such as isobutylene; alkyl or aryl vinyl ethers such as isobutyl vinyl ether, phenyl vinyl ether and octyl vinyl ether; halogenated olefins such as vinylidene chloride, vinyl fluoride, allyl chloride and vinyl bromide; ethyl acrylate, n
-Butyl acrylate, n-butyl methacrylate, 2
-Ethylhexyl acrylate, 2-ethylhexyl methacrylate, acrylic acid or methacrylic acid esters such as stearyl methacrylate; acrylic acid, methacrylic acid, crotonic acid, acrylonitrile, maleic anhydride, and acrylic derivatives such as itaconic anhydride; These can be used alone or in combination of two or more.

Examples of the polymer which can be graft-copolymerized with a vinyl chloride monomer include ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer, chlorinated polyethylene, polyurethane, and polybutadiene-styrene. -Methyl methacrylate copolymer (MB
S), polybutadiene-acrylonitrile- (α-methyl) styrene copolymer (ABS), polybutyl acrylate, butyl rubber, polystyrene, styrene-butadiene copolymer, cross-linked acrylic rubber, and the like. It can be used in combination of the above.

In addition to the dispersion stabilizer used in the present invention, other dispersion stabilizers may be used without any problem as long as the effects of the present invention are not impaired. Soluble partially saponified polyvinyl alcohol; water-soluble cellulose such as methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose; acrylic acid polymer;
Water-soluble polymers such as methyl vinyl ether-maleic anhydride copolymer, styrene-maleic anhydride copolymer, and gelatin; oils such as sorbitan monolaurate, sorbitan monostearate, glycerin monostearate, and ethylene oxide propylene oxide block copolymer Soluble emulsifier, polyoxyethylene sorbitan monolaurate, polyoxyethylene glycerin oleate,
Water-soluble emulsifiers such as sodium laurate,
These can be used alone or in combination of two or more.

In the present invention, the vinyl chloride polymer is
A substance mainly composed of a polymer obtained by polymerizing a vinyl chloride monomer or a mixture of a vinyl monomer copolymerizable with a vinyl chloride monomer, and a lubricant, a gelling improver as appropriate. Further, additives such as a pH adjuster, a chain transfer agent, an antistatic agent, a cross-linking agent, a defoaming agent, a stabilizer, a filler, an antioxidant, and a scale adhesion inhibitor may be added. These can be added at the beginning of polymerization, during polymerization, or after polymerization.

The polymerization time in the present invention is within 6 hours,
Preferably, it is 1 to 6 hours, more preferably, 1 to 4 hours. By doing so, it is possible to realize the production of a vinyl chloride polymer having high productivity. Here, the polymerization time is the time from the point when the polymerization raw materials are charged and the internal temperature reaches a predetermined temperature by raising the temperature, to the point when the pressure in the polymerization vessel drops 2.0 kg / cm ² from the initial pressure. Is the polymerization time. In addition, even if it is a polymerization method in which the polymerization is terminated at a time when the decrease in the internal pressure is smaller than 2.0 kg / cm ² , the decrease in the internal pressure is reduced within 6 hours when the polymerization is continued under normal conditions. Polymerization of 2.0 kg / cm ² is included in the scope of the present invention. Such polymerization is substantially the same as the polymerization method of the present invention in which the polymerization end time is defined as above within 6 hours after the above-described polymerization end time. Because it is different.

As the reflux condenser attached to the polymerization vessel used in the method of the present invention, a known condenser can be used, and the method of controlling the reflux condenser is controlled so that the heat removal rate of the reflux condenser is 30% or more of the polymerization heat removal amount. Then, there is no particular limitation, and a known method, a method described in a document, or the like is applied. (For example, Saeki, Nagami, eds .: New Polymer Manufacturing Process (issued by the Industrial Research Institute), page 158, Table 6.5)

In the present invention, the stirrer of the polymerization vessel is not particularly limited, and a baffle may be used if desired. Examples of the stirrer include a turbine blade, a fan turbine blade, a Faudler blade, and a blue margin blade which are usually used for polymerization of a vinyl chloride monomer, and baffles include a finger type, a cylindrical type, a D type, and a loop type. You.

The scale adhesion preventive in the present invention can be applied by a known method by a known method. Preferably, it is performed prior to the polymerization of each batch, but it is not always necessary to apply it before charging each polymerization batch. As specific examples of the scale adhesion inhibitor, for example, a condensate of a compound having a phenolic hydroxyl group can be used, particularly a self-condensate of a compound having a phenolic hydroxyl group, a condensate of a compound having a phenolic hydroxyl group, and a modified product thereof. Is mentioned.

The scale adhesion inhibitor preferably used in the method of the present invention is a resol type initial condensate obtained by reacting a phenol and an aldehyde in the presence of a basic catalyst, more preferably Modified products modified with various modifying agents. Examples of phenols include, for example, monovalent phenols such as phenol, cresol, and ethylphenol, divalent phenols such as resorcinol and hydroquinone, bisphenols such as bisphenol A, and substituted products thereof. Alternatively, two or more kinds can be used in combination. Examples of the aldehydes include organic compounds having a CHO group such as formaldehyde, acetaldehyde, furfural, propionaldehyde, butyraldehyde, acrolein, crotonaldehyde, benzaldehyde, phenylacetaldehyde, 3-phenylpropionaldehyde, and 2-phenylpropionaldehyde. These can be used alone or in combination of two or more, and formaldehyde and acetaldehyde are particularly preferred. In addition, the above-mentioned condensates of phenols and aldehydes further include hindered phenols,
Those obtained by condensing at least one modifier selected from a nitrogen-containing compound and a polyhydric phenol in the presence of an acidic catalyst, particularly a strongly acidic catalyst, are also preferably used. The hindered phenol used in this case means a monovalent or divalent hindered phenol, and examples thereof include o-sec-butylphenol (OSBP) and 2-t-butylhydroquinone.

In the production method of the present invention, the initial stage of polymerization,
During or after polymerization, other gelling improvers, pH adjusters, chain transfer agents, antistatic agents, crosslinkers, defoamers, stabilizers, fillers, antioxidants, etc. are used as polymerization additives. May be.

[0049]

EXAMPLES Hereinafter, the production method of the present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited thereto. In the examples and comparative examples, the following methods were used to evaluate the yellowness of the dispersion stabilizer, the observation of the state of adhesion of the scale to the reflux condenser, the measurement of the average particle size, the initial coloring property, the fish eye, and the roll adhesiveness. In addition, the number of parts in Examples shows the number of parts by weight with respect to the vinyl chloride monomer unless otherwise specified.

(Yellowness of Dispersion Stabilizer) The dispersion stabilizer was put into a measurement cell in a powder state, and measured in accordance with JIS K-7105. A photoelectric colorimeter (MODEL1001DP manufactured by Nippon Denshoku Industries Co., Ltd.) was used as a measuring instrument. The larger the YI, the stronger the yellowness and the more colored.

(Observation of Scale Adhesion on Reflux Condenser)
After completion of the polymerization, the slurry in the polymerization vessel was discharged, and then the interior of the polymerization vessel was washed with water, and the state of scale adhesion in the reflux condenser was visually observed according to the following criteria.

○ (Almost no scale adhesion) △ (Small amount of scale adhesion) × (Many scale adhesion) (Average particle size) The sieve analysis using a JIS standard wire net was determined to be 50% passage diameter.

(Initial Colorability) Vinyl Chloride Polymer 100
3 parts by weight of a dibutyltin malate-based stabilizer and 0.2 parts by weight of a fatty acid ester-based lubricant are blended with respect to parts by weight,
150 g of the compound was kneaded with a 6-inch roll at a roll surface temperature of 150 ° C. for 5 minutes to obtain a 1 mm-thick sheet compact. Subsequently, the sheet compacts were laminated, and a 5 mm press compact was obtained by 180 ° C. press under the conditions of preheating for 15 minutes, forming pressure of 50 kg / cm 2 and press time of 20 minutes.
The initial colorability was determined by measuring the yellow value (YI) of the molded product with a color difference meter. The smaller the value of YI, the better the initial coloring property. A photoelectric colorimeter (MODEL1001DP manufactured by Nippon Denshoku Industries Co., Ltd.) was used as a measuring instrument.

(Fisheye) Vinyl chloride polymer 1
A sheet obtained by mixing 40 parts by weight of di-2-ethylhexyl phthalate, 3 parts by weight of a Ca-Zn composite metal soap stabilizer, and a small amount of ultramarine blue with 00 parts by weight, and kneading with a roll at 160 ° C. for 3 minutes. The number of fish eyes observed in 50 cm 2 was counted.

(Roll Adhesion) Vinyl Chloride Polymer 10
4 parts by weight of a dibutyltin malate-based stabilizer and 1.5 parts by weight of a fatty acid ester-based lubricant were added to 0 parts by weight. This composition was kneaded with two 8-inch rolls having a surface temperature of 185 ° C. on a roll and kneaded for 5 minutes, and the sheet was taken out. Then, the same operation was repeated five times to evaluate the ease of peeling of the sheet. Evaluation criteria of calendering processability ○ No sticking (peeling without problems) △ Slight sticking (easy peeling) × large sticking (slightly peeling) XX sticking severe (hard to peeling) Example 1 A stirrer with an internal volume of 120 m ³ , Deionized water is added to a stainless steel polymerization vessel equipped with an outer jacket and a reflux condenser.
000 kg, the dispersion stabilizer (A) and the dispersion stabilizer (B) shown in Table 1 were charged, and 18 kg of tert-hexylperoxypivalate was added thereto, and the pressure was reduced. Dispersion stabilizer (A)
Is obtained by dissolving a commercially available polyvinyl alcohol (yellowness of about 70) in water, and filtering it with activated carbon to a yellowness of 35.

Next, 36000 kg of vinyl chloride monomer
And heated to 67 ° C. through hot water in the jacket while stirring the inside of the polymerization vessel, polymerization was started while maintaining this temperature, cooling water was passed through the reflux condenser, and the load was adjusted while refluxing. Polymerization proceeded when the heat removal ratio of the condenser was 40% of the polymerization calorific value. When the pressure in the polymerization reactor dropped 2.0 kg / cm ² from the pressure in the steady state of the polymerization reaction, the unreacted vinyl chloride monomer was recovered. The polymerization time was 4 hours.

When the slurry was taken out of the polymerization vessel and dehydrated and dried, a vinyl chloride polymer was obtained at a polymerization conversion of 85%. Table 1 shows the evaluation results of the obtained vinyl chloride polymers. The obtained vinyl chloride polymer has high production efficiency,
It was excellent in initial coloring property, fish eye and roll adhesiveness. The scale adhesion condition in the reflux condenser was good.

Example 2 A vinyl chloride polymer was produced in the same manner as in Example 1 except that the type of the dispersion stabilizer was changed. The dispersion stabilizer (A) is obtained by dissolving commercially available polyvinyl alcohol in water,
The yellowness was adjusted to 5 by activated carbon filtration.

The slurry was taken out of the polymerization vessel and dehydrated and dried to obtain a vinyl chloride polymer at a polymerization conversion of 85%. Table 1 shows the evaluation results of the obtained vinyl chloride polymers. The obtained vinyl chloride polymer has high production efficiency,
It was excellent in initial coloring property, fish eye and roll adhesiveness. The scale adhesion condition in the reflux condenser was good.

Example 3 The same procedure as in Example 2 was carried out except that the lubricant shown in Table 1 was converted into an emulsified aqueous solution (aqueous lubricant emulsified solution concentration of 30% by weight) was added to the polymerization system at a polymerization conversion rate of 30% by weight. Was performed. The polymerization time was 4 hours.

The slurry was taken out of the polymerization vessel and dehydrated and dried to obtain a vinyl chloride polymer at a polymerization conversion of 85%.

Table 1 shows the evaluation results of the vinyl chloride polymer. The obtained vinyl chloride polymer has high production efficiency,
It was excellent in initial coloring property, fish eye and roll adhesiveness. The scale adhesion condition in the reflux condenser was good.

Example 4 The same polymerization as in Example 1 was continuously carried out in a closed mode for 80 batches. Before the start of the polymerization, a scale adhesion inhibitor was sprayed on the inner wall of the polymerization vessel and applied, followed by sufficient washing.

After discharging the slurry of the last batch and washing the inside of the polymerization machine with water, the vinyl chloride monomer remaining in the polymerization machine was recovered in the same manner as in Example 1, and the vinyl chloride monomer remaining in the polymerization machine was recovered. The body was recovered and the inside of the polymerization vessel was replaced with air to open a manhole. The average conversion was 83%. Table 1 shows the experimental results. The physical property values are those of the last batch.

Comparative Example 1 Example 1 was repeated except that the dispersion stabilizers shown in Table 2 were used.
The same operation as described above was performed. The polymerization time was 4 hours. The dispersion stabilizer (B) is the same as that used in Example 1.

When the slurry was taken out of the polymerization vessel and dehydrated and dried, a vinyl chloride polymer was obtained at a polymerization conversion of 85%.

Table 2 shows the evaluation results of the obtained vinyl chloride polymer. The obtained vinyl chloride polymer had high production efficiency and excellent fisheye and roll adhesiveness, but had poor initial coloring properties.

Comparative Example 2 Example 1 except that the dispersion stabilizers shown in Table 2 were used.
The same operation as described above was performed. The polymerization time was 4 hours. The dispersion stabilizer (A) has a reduced yellowness due to activated carbon filtration.

The slurry was taken out of the polymerization vessel and dehydrated and dried. As a result, a vinyl chloride polymer was obtained at a polymerization conversion of 85%.

Table 2 shows the evaluation results of the obtained vinyl chloride polymer. The obtained vinyl chloride polymer had high production efficiency and was excellent in initial coloring property and roll adhesiveness, but had poor fisheye. Also, the particle size tends to be coarse, and the powder characteristics were not satisfied. However, the scale adhesion condition in the reflux condenser was good.

Comparative Example 3 Example 1 except that the dispersion stabilizers shown in Table 2 were used.
The same operation as described above was performed. The polymerization time was 4 hours. The dispersion stabilizer (A) has a reduced yellowness due to activated carbon filtration.

The slurry was taken out of the polymerization vessel and dehydrated and dried to obtain a vinyl chloride polymer at a polymerization conversion of 85%.

Table 2 shows the evaluation results of the obtained vinyl chloride polymer. The obtained vinyl chloride polymer had high production efficiency and excellent initial coloring properties, but had poor fisheye and roll adhesiveness. Also, the particle size tends to be coarse, and the powder characteristics were not satisfied. Further, when the inside of the reflux condenser was observed, a small amount of film scale was formed on the wall surface.

[0074]

[Table 1]

[0075]

[Table 2]

[0076]

As described above, according to the present invention,
In suspension polymerization, YI ′ is set to 30 or less, and a dispersion stabilizer having specific properties is used, so that productivity, roll adhesiveness in calendering processing, fisheye characteristics of molded articles, and molding With regard to the initial colorability of the product, it is possible to produce a vinyl chloride-based polymer exhibiting a high level of properties in any case.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08K 5/03 C08K 5/03 C08L 27/06 C08L 27/06 // (C08L 27/06 23:02) F-term (reference) 4J002 AE032 AE052 BB032 BB122 BD041 BD051 BD061 BD071 BD081 BD091 EB156 FD010 FD020 FD030 FD100 FD140 FD172 FD176 4J011 AA05 AB03 DA03 DB05 EB04 EB08 EC04 JA07 JA10 JB03 A07 BA03 AC02Q AC03P AC04Q AC22Q AC23Q AC37Q AE02Q AE06Q AE09Q AG02Q AG04Q AJ01Q AJ02Q AK31Q AK32Q AL03Q AL04Q AL05Q AM02Q BC43Q CA01 CA04 DA43 DA61 FA03 FA21 FA47

Claims (6)

[Claims] 1. A polymerization apparatus having an internal volume of 100 m ³ or more provided with a stirrer, a jacket and a reflux condenser is used. The amount of heat removed by the reflux condenser during polymerization is set to 30% or more of the total heat removal. When the vinyl chloride monomer is subjected to suspension polymerization in an aqueous medium in the presence of an oil-soluble polymerization initiator under a polymerization condition of 6 hours or less, (A) a saponification degree of 75 ~ 90 mol%, average polymerization degree 1500
-3000 partially-saponified polyvinyl alcohol in an amount of 0.02-0.15 per 100 parts by weight of the vinyl chloride monomer.
Parts by weight (B) hydroxypropyl methylcellulose and / or saponification wherein the degree of methoxy substitution is 15 to 40% by weight, the degree of hydroxypropoxy substitution is 5 to 25% by weight, and the viscosity of the 2% by weight aqueous solution at 20 ° C. is 10 to 80 cps. Of partially saponified polyvinyl alcohol having a degree of polymerization of 25 to 65 mol% and an average degree of polymerization of 200 to 1000
Using 0.005 to 0.05 parts by weight to 00 parts by weight, the converted yellowness YI ′ defined by the following formula (1) is used.
Is 30 or less, the method for producing a vinyl chloride polymer. _{YI '= α A YI A +} α B YI B ... (1) ( wherein, alpha _A, alpha and _B are, dispersion stabilizer to the total dispersion stabilizer (A), represents the weight content of (B), YI _A ,
Each YI _B is defined dispersion stabilizer in JIS K-7105 (A), it represents the yellowness index YI value of (B). ) 2. The method for producing a vinyl chloride polymer according to claim 1, wherein the reduced yellowness YI ′ is 20 or less. 3. The total of the dispersion stabilizer (A) and the dispersion stabilizer (B) is 0.0% based on 100 parts by weight of the vinyl chloride monomer.
The method for producing a vinyl chloride polymer according to claim 1 or 2, wherein the amount is 3 to 0.2 parts by weight, and the weight ratio of (A) / (B) is 0.5 to 4. 4. The process for producing a vinyl chloride polymer according to claim 1, wherein the suspension polymerization is carried out in a closed mode after applying a scale adhesion inhibitor to the inner wall of the polymerization vessel. Method. 5. A lubricant comprising at least one compound selected from the group consisting of polyolefins, paraffins, and chlorinated hydrocarbons and having an average particle size of 300 μm or less, at the beginning of polymerization, during polymerization, or after completion of polymerization. 5. The method for producing a vinyl chloride-based polymer according to claim 1, wherein 0.001 to 0.3 parts by weight is added to 100 parts by weight of the vinyl chloride-based monomer in a slurry state. Method. 6. A vinyl chloride polymer produced by the method for producing a vinyl chloride polymer according to claim 1.