JPH09110907A - Production of high-bulk density polyvinyl chloride - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a production process of PVC by aq. suspension polymn. whereby PVC having a high bulk density and an excellent porosity giving finished goods with few fish-eyes is obtd. while discharging waste water contg. little suspended substances even when the reaction time is short. SOLUTION: Polyvinyl alcohol having a degree of polymn. of 200 or higher but lower than 1,500 and a degree of saponification of 97mol% or higher, polyvinyl alcohol having a degree of polymn. of 1,100 or higher and a degree of saponification of 70-85mol%, and hydroxypropyl methyl cellulose and/or hydroxypropyl cellulose having a surface tension of 0.1wt.% aq. soln. of 100dyn/cm or lower at 25 deg.C are used as the dispersant in the aq. suspension polymn. of vinyl chloride.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a PVC having a high bulk specific gravity, excellent porosity, and a small number of fisheyes as a processed product, which is obtained by the aqueous suspension polymerization method. The present invention relates to a method for producing polyvinyl chloride containing little suspended matter.

[0002]

2. Description of the Related Art Generally, polyvinyl chloride (hereinafter abbreviated as PVC) is a useful resin having excellent physical and mechanical properties and is widely used as a hard and soft material. As a molding method of PVC, calender molding, extrusion molding, injection molding and the like are generally used, but particularly in the case of hard extrusion molding, the bulk density is high (0.55 g / ml or more) from the viewpoint of increasing the extrusion amount. Development of PVC is desired.

When aqueous suspension polymerization of vinyl chloride is carried out, the bulk specific gravity is increased by adding a highly saponified polyvinyl alcohol having a small surface activity, a polyvinyl alcohol having a medium saponification degree and a cellulose derivative having a low surface tension as a dispersant. high,
P with excellent porosity and less processed fish eyes
It is known that VC can be obtained. (JP-A-57-7
However, in the above-mentioned conventional method, the amount of suspended matter was small in the wastewater generated when the four slurries formed by the aqueous suspension polymerization were separated into cake and water, but the productivity was improved and the production amount was increased. When a large amount of the dispersant used in the polymerization is used to cope with the above, the suspended solids in the wastewater increase, and a lot of labor must be spent on the wastewater treatment.

[0004]

The present invention, which has not been realized in the prior art, has a high bulk specific gravity and excellent porosity due to an aqueous suspension polymerization method, and therefore has less fish eyes in processed products, Moreover, it is an object of the present invention to provide a method for producing PVC in which the suspended matter in the waste water is small even if the reaction time is shortened.

[0005]

The present inventors have arrived at the present invention as a result of intensive studies to solve the above problems.

That is, the present invention uses (A) the degree of polymerization of 1500 as a dispersant when carrying out aqueous suspension polymerization of vinyl chloride.
Less than 200, saponification degree of 97 mol% or more, polyvinyl alcohol, (B) polymerization degree of 1100 or more, saponification degree of 70 to 85
Mol% polyvinyl alcohol and (C) 0.1% by weight
The surface tension of the aqueous solution at 25 ° C is 100 dyne / c
It is an object of the present invention to provide a method for producing polyvinyl chloride having a high bulk specific gravity, which is characterized by using hydroxypropylmethyl cellulose and / or hydroxypropyl cellulose having an m or less and having a small amount of suspended substances in waste water.

Further, in the above-mentioned production method of the present invention, the dispersant (A) is 25 to 70% by weight based on the total amount of the dispersant,
Dispersant (B) is 10 to 65% by weight, dispersant (C) is 1 to
It is to provide a method which is 30% by weight.

According to the above-mentioned method, PVC has a high bulk specific gravity and excellent porosity, so that the processed product has few fish eyes, and moreover, even if the reaction time is shortened, there is little PVC in the waste water generated in the manufacturing process. It has become possible to provide a manufacturing method of.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the method of the present invention, (A) the degree of polymerization is less than 1500 to 200 and the degree of saponification is 97 mol% to 1.
Polyvinyl alcohol having a high saponification degree of 00 mol% is used for increasing the bulk specific gravity. The degree of polymerization of the polyvinyl alcohol used is preferably less than 1500 to 200,
1300 to 300 are more preferable, 1000 to 400
Is particularly preferable, and 800 to 400 is most preferable. When the degree of polymerization is 1500 or more, the amount of suspended matter generated in the waste water generated when the slurry obtained by the aqueous suspension polymerization is separated into a cake and water increases, which is not desirable from the viewpoint of wastewater treatment labor. Since the porosity of the obtained polyvinyl chloride powder is lost, the amount of residual monomer in the slurry after demomerization of the polymerization slurry also increases. When the amount of residual monomer in the slurry after demonomerization increases, the amount of residual monomer in the PVC powder after drying increases,
In order to reduce it, the drying process becomes complicated and labor and cost increase, which is not preferable.

The amount of the dispersant used is 25 to the total amount of the dispersant.
It is preferably 70% by weight, more preferably 25 to 60% by weight, particularly preferably 30 to 55% by weight. If the amount is less than 25% by weight, high bulk specific gravity PVC cannot be obtained,
When the content is more than 10% by weight, the porosity of the obtained PVC is reduced and the fisheye of the processed product is deteriorated. Further, in a severe case, coarse particles are generated and it cannot be used as a normal PVC powder. The dispersant (B) used in the present invention has a degree of polymerization of 1100 or more, preferably 1100 to 40.
00, particularly preferably 1500 to 3000, and having a saponification degree of 70 to 85 mol%, a polyvinyl alcohol having a medium saponification degree is
The amount of the dispersant is preferably 10 to 65% by weight, more preferably 20 to 60% by weight, and particularly preferably 30 to 60% by weight. If the amount is less than 10% by weight, coarsening of PVC occurs, and if it exceeds 65% by weight, high bulk specific gravity PVC cannot be obtained.

Next, the dispersant (C) used in the present invention is hydroxypropylmethyl cellulose and / or hydroxypropyl cellulose, and the surface tension of a 0.1 wt% aqueous solution at 25 ° C. is 100 dyne / cm or less. Those of -60 dyne / cm are particularly preferable. The amount of this dispersant used is 1 to 30% by weight of the total amount of the dispersant.
Is more preferable, 1 to 25% by weight is more preferable, and 2 to 20% by weight is particularly preferable. If the amount is less than 1% by weight, the fish eyes of the processed product increase, and if it exceeds 30% by weight, the particle size distribution becomes wide, which is not preferable.

In the method of the present invention, the amount of the total dispersant used is usually 0.02 to 100 parts by weight of vinyl chloride.
A range of 0.2 parts by weight is suitable.

[0013] The method of the present invention can be used a known polymerization vessel and equipment is effective in improving the productivity, the volume of the polymerization vessel is preferably 20～350M ^3, more preferably 40~250m ^3, 50~ 200 m ³ is particularly preferred. A large-sized polymerization vessel is preferable from the viewpoint of construction cost and operation cost, but when the polymerization vessel volume exceeds 350 m ³ , the internal surface area of the polymerization vessel becomes small with respect to the polymerization vessel volume, and the heat removal efficiency decreases, which is not realistic.

A reflux condenser is preferably used for heat removal of the polymerizer with a volume of more than 50 m ³ . Known reflux condensers, for example, Japanese Patent Publication No. 61-
What is described in the claims of 17841 and each example is illustrated.

When the reaction time is shortened, the amount of the catalyst used in the polymerization must be increased, and the particle size of the PVC obtained becomes large when the amount of the catalyst is increased. The amount had to be increased. Then, increasing the amount of the dispersant causes a problem because suspended solids in the wastewater generated in the PVC manufacturing process increase.
Since the dispersant system according to the invention has a lower amount of suspended matter in the waste water, it is particularly effective to use the dispersant system according to the invention when the reaction time is shortened.

In the suspension polymerization of the present invention, water is used as a medium, but the ratio of water to vinyl chloride monomer (water / vinyl chloride monomer weight ratio) is preferably 0.8.
˜1.5, more preferably 0.85 to 1.2, and particularly preferably 0.9 to 1.1.

The method of the present invention can be applied to polymerization of vinyl chloride, copolymerization containing vinyl chloride as a main component, and graft polymerization.

The monomer copolymerized with vinyl chloride is not particularly limited as long as it is a monomer usually used for copolymerization of vinyl chloride. For example, vinyl acetate, vinyl caproate, vinyl laurate, vinyl starate, and the like vinyl. Olefins such as esters, ethylene, propylene, butene and isobutylene, vinyl ethers such as isobutyl vinyl ether, octyl vinyl ether, dodecyl vinyl ether and phenyl vinyl ether,
Halogenated olefins such as vinylidene chloride, vinyl fluoride, propylene chloride, vinyl bromide, etc., acrylates such as ethyl acrylate, n-butyl acrylate, n-butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, stearyl acrylate, etc. Examples thereof include acrylic acid, methacrylic acid, acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconic anhydride, acrylonitrile, and methacrylonitrile. These may be used alone or with respect to vinyl chloride. It is preferably used in an amount of 15% by weight or less.

The graft polymerization can be carried out by a known graft polymerization method in which vinyl chloride is graft-polymerized to the polymer, and the above-mentioned polymer used in this case is, for example, ethylene-vinyl acetate copolymer (EVA), Examples thereof include ethylene-ethyl acrylate copolymer, chlorinated polyethylene, polyurethane, butadiene-styrene-methyl methacrylate (MBS), polybutyl acrylate, butyl rubber, polystyrene, and styrene-butadiene copolymer.

In the present invention, a known oil-soluble radical catalyst can be used as a polymerization catalyst. For example, diisopropyl peroxydicarbonate, dioctyl peroxydicarbonate, dilauryl peroxydicarbonate,
Dimyristyl peroxydicarbonate, dicetyl peroxydicarbonate, ditertiarybutyl peroxydicarbonate, di (ethoxyethyl) peroxydicarbonate, di (methoxyisopropyl) peroxydicarbonate, di (3methoxybutyl) peroxy Dicarbonate, di (3methoxy3-methylbutyl) peroxydicarbonate, di (butoxyethyl) peroxydicarbonate, di (2isopropoxyethyl) peroxydicarbonate, di (2isopropoxyethyl) peroxydicarbonate, di Benzyl peroxydicarbonate, dicyclohexyl peroxydicarbonate,
Percarbonate such as ditertiary butyl cyclohexyl peroxy dicarbonate, tert-butyl peroxy neodecaneate, amyl peroxy neodecaneate, tertiary-octyl peroxy neodecaneate, α-cumylperoxy neodecaneate, 2, 4,
4-trimethylpentyl peroxy 2 neodecanoate,
Tertiary butyl peroxypivalate, amyl peroxypivalate, tert-octyl peroxypivalate, α-cumyl peroxypivalate, perhexyl oxalate, ditertiary butyl peroxy oxalate, acetylcyclohexyl sulfonyl peroxide Peresters such as 1,1,3,3, terolamethylbutylperoxyphenoxyacetate, lauroyl peroxide, diisobutyl peroxide,
Diacyl peroxide such as 2 ethylhexanoyl peroxide, 3,5,5 trimethylhexanoyl peroxide, 2,2 ′ azobisisobutyronitrile,
2,2 'asobis-2,4 dimethylvaleronitrile,
An azo compound such as 2,2 ′ asobis-4methoxy-2,4dimethylvaleronitrile can be exemplified.

Further, water-soluble peroxides such as potassium persulfate and ammonium persulfate, 2,2'-azobis (2-aminodipropane) hydrochloride, 2,2'-azobis (N, N'-dimethyleneisobutyl) Water-soluble azo compounds such as amidine) hydrochloride can also be used as a polymerization catalyst.

It is preferable to use a combination of two or more kinds of catalysts having different 10-hour half-lives in order to make the polymerization reaction rate uniform.

In the present invention, the temperature of the polymerization reaction is 40 to
The range of 70 ° C. is preferable, and the polymerization time is preferably 3 to 12 hours, more preferably 3 to less than 7 hours, and particularly preferably 3 to 6 hours. When the polymerization time exceeds 12 hours, it is not desirable from the viewpoint of productivity improvement, and when it is less than 3 hours, it is necessary to increase the catalyst amount. In that case, the heat generation amount exceeding the heat removal capacity of the polymerization reactor is required. If it occurs, the control of the polymerization temperature becomes unstable.

In the present invention, the polymerization time means the time from when the internal temperature of the polymerization vessel is raised until the reaction is stopped.

Since the dispersant system of the present invention has a characteristic peculiar to the dispersant system of the present invention that the amount of suspended solids in the waste water is small even when the reaction time is short, the reaction time can be shortened, and particularly the reflux can be performed. The use of the condenser has an excellent effect that the reaction time can be shortened even in a large-sized polymerization vessel.

In the method of the present invention, in order to improve productivity, it is necessary to apply a wall adhesion preventive agent to the wall surface of the polymerization vessel or the like in contact with the vinyl chloride monomer to reduce the cleaning frequency. The material can be applied by a known method. The coating is preferably carried out before charging the raw materials, but it is not necessary to apply it for each polymerization. As the wall adhesion preventing agent, those known as a vinyl chloride wall adhesion preventing agent can be used. For example, a condensate of a compound having a phenolic hydroxyl group can be used, and a self-condensate of a compound having a phenolic hydroxyl group, a condensate of a compound having a phenolic hydroxyl group, and modified products thereof are particularly preferable. For example, as the wall adhesion preventing agent, those described in the claims of JP-B-6-62709 and each of the examples can be preferably used.

In the present invention, it is free to use other dispersion aids and additives as long as the object of the present invention is not impaired. As such, alcohols, fatty acids, esters, buffers and the like can be mentioned.

According to the method of the present invention, PVC having a high bulk specific gravity and excellent porosity can be obtained from the viewpoint of the fish eye of the processed product, and it is possible to obtain a PVC of good quality without coarse particles, and Even if the reaction time is shortened, the amount of suspended solids in the wastewater is small, so the wastewater treatment effort is small,
Its industrial significance is great. The PVC obtained by the method of the present invention is particularly suitable for hard extrusion molding, and has an advantage that the extrusion amount is high because of its high bulk specific gravity.

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The parts in the following description are parts by weight. The physical properties were measured as follows.

(1) Suspended substance amount in waste water Measured according to JIS K0120.

(2) Residual Monomer in Slurry First, 100 ml of acetone containing 1% by weight of t-butylcatechol (polymerization inhibitor) was put into a 300 ml Erlenmeyer flask exactly, and 30 to 50 g of polyvinyl chloride slurry was added thereto. Add the sample rapidly and plug tightly to obtain the accurate sample weight from the difference in mass before and after. Next, this Erlenmeyer flask containing PVC slurry and acetone is immersed for 1 hour to extract the vinyl chloride monomer into the liquid layer, and then vinyl chloride is quantified using a gas chromatograph with a hydrogen flame detector. The obtained measured vinyl chloride monomer concentration was divided by the slurry concentration and converted into a unit weight of resin.

(3) Bulk Specific Gravity According to JIS K6721 (4) Plasticizer Absorption (Porosity) 5 g of resin was precisely weighed and taken into a glass filter having a roughness of G-2, and about 10 ml of plasticizer DOP was added. And mix well. Thereafter, free DOP is separated and removed by a centrifuge with a rotation speed of 5000 rpm, and the remaining weight is measured to determine the DOP absorption amount of the resin. The unit is represented by the DOP absorption amount (phr) per 100 parts of the resin.

(5) Fish Eyes The following composition was mixed well, 8 inches in diameter, two rolls were heated to 145 ° C. and kneaded for 5 minutes, and the sheet was taken out from the roll gap of 0.3 mm. After that, length 15 x width 1
Count the number of fish eyes present on the 0 cm sheet. Resin 100 g DOP 60 g Ca-Zn-based stabilizer 1 g carbon 0.5 g (6) Productivity In the cycle time of batch polymerization, miscellaneous times other than polymerization time (raw material charging time, slurry discharge time, etc.) are 2.
5 hours, polymerization chamber inner volume 1 m ³ , PV per month
It was shown as the production amount (ton) of C.

Example 1 Internal volume 120 m^Three Polymerization with a reflux condenser installed
Apply an anti-sticking agent to the inner wall of the reactor by spraying and polymerize
The inside of the reactor was thoroughly washed with water. Then 40 tons of deionized water
n, as a dispersant (A) polymerization degree 700 (4% by weight water-soluble
Solution, viscosity at 20 ° C. 5 cps), saponification degree 98 mol%
Livinyl alcohol 0.05 parts (vinyl chloride monomer 1
(Weight to 00 parts, the same applies below)
Polyvinyl alcohol with a saponification degree of 80 mol% 0.045
Part and (C) 0.1 wt% aqueous solution has a surface tension of 48 d.
hydroxypropylmethylcellulose of yne / cm
After charging 0.005 parts, the air inside the polymerization reactor is
Excluded by vacuum pump. Then vinyl chloride monomer
-40 tons, as a polymerization catalyst (1) 60% by weight in purity
Di-2-ethylhexyl peroxydicarbonate water
Maruzon 452ppm (based on the weight of vinyl chloride monomer)
And the net weight of catalyst, the same applies hereinafter), and (2) purity of 50
Amount of Cumyl Peroxyneodecanoate Water Emulsion
226 ppm was pumped in. Reaction temperature is 57 ℃
The polymerization reaction was started to 8.8 kg / cm. ^Two Heavy with G
When the combined reaction was carried out, the reaction was started 4.5 hours after the temperature started to rise.
Pressure in the reaction tank is 6 kg / cm^Two Fell to G. Therefore
0 kg / cm of unreacted monomer at 75 ° C ^Two Until G
The vinyl chloride slurry collected and obtained is a slurry tank.
Was transferred to. The PVC yield was 85%. at the time
And the concentration of residual vinyl chloride monomer in the PVC slurry is
It was 14000 ppm. Poke this PVC slurry
Feed vinyl chloride monomer to stripping tower
Diffusing PVC slurry and countercurrent contact with steam
Vinyl chloride mono in PVC slurry by touch
Stripped the mar. Filter this PVC slurry
It was dehydrated and the filter cake was dried. Generated by filtration
The amount of suspended solids in the discharged wastewater was 41 mg / l. S
Residual unreacted vinyl chloride in the PVC slurry after tripping
When the amount of the nil monomer was measured, it was 48 ppm.
Was. The bulk specific gravity of the obtained PVC is 0.56 g / ml,
Plasticizer absorption (porosity) is 20 phr and particle size distribution is 60
All the mash has no coarse particles and fine powder of 200 mesh
Only 1%. There are only two fish eyes
Was. The results are shown in Table 1.

Example 2 Instead of the dispersant (A) used in Example 1, the degree of polymerization was 13
00 (4 wt% aqueous solution, viscosity at 20 ° C. 14 cps),
Example 1 was repeated except that 0.05 part of polyvinyl alcohol having a saponification degree of 98 mol% was used. PVC obtained
Had a bulk specific gravity of 0.56 g / ml and the amount of suspended solids in the wastewater was 71 mg / ml. Plasticizer absorbency (porosity) is 2
At 0 phr, the particle size distribution was all 60 mesh and no coarse particles, and only 2% of fine powder passed 200 mesh. The number of fish eyes was one. The results are shown in Table 1.

Comparative Example 1 Instead of the dispersant (A) used in Example 1, a polymerization degree of 20 was used.
00 (4% by weight aqueous solution, viscosity at 20 ° C. 54 cps) 0.05 part of polyvinyl alcohol having a saponification degree of 98 mol% was used in the same manner as in Example 1 except that the amount of suspended matter in the waste water was 390 mg / I became a lot. The results are shown in Table 1.

Comparative Example 2 Instead of the dispersant (A) used in Example 1, a polymerization degree of 20 was used.
00 (4 wt% aqueous solution, viscosity 44 cps at 20 ° C.),
The procedure of Example 1 was repeated except that 0.05 part of polyvinyl alcohol having a saponification degree of 88 mol% was used, but the amount of suspended matter in the waste water increased to 430 mg / l. The results are shown in Table 1.

Comparative Example 3 The amount of the dispersant used in Example 1 was (A) 0.085 part,
(B) The same procedure as in Example 1 was carried out except that the content was 0.01 part, but the PVC particles were very large, and normal PVC which could be evaluated as PVC powder was not obtained. The results are shown in Table 2.

Comparative Example 4 The amount of the dispersant used in Example 1 was 0.01 part (A),
(B) The same procedure as in Example 1 was carried out except that the content was 0.085 parts, but the bulk specific gravity of the obtained PVC was low. The results are shown in Table 2.

Comparative Example 5 The amount of the dispersant used in Example 1 was 0.03 part (A),
The same procedure as in Example 1 was carried out except that (B) 0.03 part and (C) 0.04 part were used, but the bulk specific gravity of the obtained PVC was low. The results are shown in Table 2.

Comparative Example 6 The amount of the dispersant used in Example 1 was (A) 0.05 part,
The same procedure as in Example 1 was carried out except that (B) 0.05 part and (C) 0 part were used, but the porosity of the obtained PVC was lost and fish eyes increased. The results are shown in Table 2.

Example 3 A polymerization vessel equipped with a back-flow condenser having an internal volume of 7 m ³ was used. Deionized water was 2.1 tons, vinyl chloride monomer was 2.1 tons, and the amount of the dispersant used in Example 1 was (A). ) 0.05 part, (B) 0.045 part, (C) 0.0
05 parts, catalyst (1) 350ppm, catalyst (2) 175p
Polymerization was performed in the same manner as in Example 1 except that pm was used. 5.5 hours after the temperature starts to rise, the pressure in the reaction tank is 6 kg.
/ Cm ² G. The results are shown in Table 3.

Comparative Example 7 Example except that 0.05 part of polyvinyl alcohol having a polymerization degree of 2000 (4 wt% aqueous solution, viscosity at 20 ° C. of 54 cps) and a saponification degree of 98 mol% was used in place of the dispersant (A). Same as No. 3, but the amount of suspended solids in the wastewater is 181m
It increased to g / l. The results are shown in Table 3.

Example 4 As a dispersant (C), the surface tension of a 0.1% by weight aqueous solution was 4
8 dyne / cm hydroxypropyl cellulose
005 parts, catalyst (1) 350 ppm, catalyst (2) 175
Polymerization was performed in the same manner as in Example 1 except that ppm was used.
5.5 hours after the temperature was started, the pressure in the reaction tank was 6k.
It decreased to g / cm ² G. The results are shown in Table 4.

[0045]

[Table 1]

[0046]

[Table 2]

[0047]

[Table 3]

[0048]

[Table 4]

[0049]

EFFECTS OF THE INVENTION According to the method of the present invention, PVC having a high bulk specific gravity and excellent porosity can be obtained in terms of the fish eye of the processed product and can be obtained without coarse particles and with excellent quality. Moreover, even if the reaction time is shortened, the amount of suspended solids in the wastewater is small, and thus the wastewater treatment labor is small, which is of great industrial significance. The PVC obtained by the method of the present invention is particularly suitable for hard extrusion molding, and has an advantage that the extrusion amount is high because of its high bulk specific gravity.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideaki Takahara 1-6 Takasago, Takaishi-shi, Osaka Prefecture Mitsui Toatsu Kagaku Co., Ltd. (72) Yoshitaka Hanno 1-6 Takasago, Takaishi-shi, Osaka Mitsui Toatsu Kagaku Within the corporation

Claims (2)

[Claims] 1. When carrying out aqueous suspension polymerization of vinyl chloride,
As a dispersant, (A) a polyvinyl alcohol having a degree of polymerization of less than 1500 to 200 and a saponification degree of 97 mol% or more, (B) a polyvinyl alcohol having a degree of polymerization of 1100 or more and a saponification degree of 70 to 85 mol%, and (C) 0.1 weight. % Aqueous solution having a surface tension of 100 dyne / cm or less at 25 ° C. of hydroxypropylmethylcellulose and / or hydroxypropylcellulose, and a method for producing polyvinyl chloride with high bulk density, characterized in that the amount of suspended matter in wastewater is small . 2. Dispersant (A) is 2 relative to the total amount of dispersant.
Claims 1 to 5 to 70% by weight, dispersant (B) to 10 to 65% by weight, and dispersant (C) to 1 to 30% by weight.
The method described in the section.