JPS5946245B2 - Suspension polymerization method of vinyl chloride - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention deals with the treatment of vinyl chloride monomers (hereinafter referred to as VC
The present invention relates to a method for producing a vinyl chloride resin, which aims to reduce the amount of VCM (denoted as M) and the amount of VCM contained in a molded body formed using the resin.

Recently, concerns about the sanitary safety of VCM in vinyl chloride resin manufacturing plants have led to a decrease in VCM concentration in the working environment at vinyl chloride resin plants and molding processing plants, and an increase in the amount of VCM released from the plant to the atmosphere. It is considered an urgent need for hygiene to reduce the CM concentration contained in molded bodies.

Industrially, vinyl chloride resins are most often manufactured mainly by suspension polymerization, and conventionally, vinyl chloride resins are produced by suspension polymerization in an aqueous medium in the presence of an azobis-based or organic peroxide-based oil-soluble radical polymerization initiator. Water-soluble synthetic polymers such as partially saponified polyvinyl acetate, methylcellulose, hydroxymethylcellulose, polyvinylpyrrolidone, polyacrylic acid, vinylacetate-maleic acid copolymer, styrene-maleic acid copolymer, or gelatin, starch, etc. water-soluble natural polymer,
Alternatively, using poorly water-soluble inorganic substances such as MgCO3, MgSO4, and BasO4 alone or in combination as a suspension stabilizer, VC
Suspension polymerization of M is being carried out.

When using a conventional suspension stabilizer, a mixture of VCM or a vinyl monomer copolymerizable therewith with CM is added at a concentration of 50 to 70%.
Suspension polymerization is carried out at ℃, and when the polymer conversion rate is 80-90%, the unpolymerized VCM is removed from the polymerization can under the VCM gas pressure at that temperature and further under reduced pressure, and the polymerization is stopped by liquefaction recovery operation, followed by dehydration and drying. After obtaining vinyl chloride resin products.
However, the vinyl chloride resin in the slurry discharged from the polymerization can after collecting unpolymerized VCM contains 1000 ppm or more of VCM, and the vinyl chloride resin product obtained after dehydration and drying contains 100 ppm or more of VCM. This increases the concentration of VCM in the working environment of vinyl chloride resin manufacturing plants and molding plants, and as a result, CM remains in molded products such as blow bottles, sheets, and films. The present invention relates to a method for effectively solving these problems.

That is, when VCM or a mixture of VCM and a vinyl monomer copolymerizable with VCM is suspension polymerized in an aqueous medium at 50 to 70°C in the presence of an oil-soluble radical initiator, 0 as a suspension stabilizer is used. The specific viscosity of .01% by weight aqueous solution at 60°C is 0.
．． 0.005 to 1 or more water-soluble polymer particles in aqueous medium
0.0001 part and 0.1 to 0.01 part of a water-soluble polymer (B) having a surface tension of 55 dyne/CTn or less at 25°C in a 0.05% by weight aqueous solution to the aqueous medium.
The surface tension of a wt% aqueous solution at 30°C is 55 dyne.
/C7n or less low molecular weight nonionic surfactant (0 is VC
It is characterized in that 0.1 to 0.01 part of M is used in combination, and unpolymerized VCM is converted into VC at a polymer conversion rate of 80 to 90%.
By recovering the M gas pressure and further under reduced pressure, the VCM contained in the vinyl chloride resin in the slurry discharged from the polymerization can becomes 30 ppm or less, and the VCM contained in the vinyl chloride resin product obtained after dehydration and drying is reduced. This is a method that shows a remarkable effect of reducing the concentration to 1 ppm or less, and is an improved method of the previously filed invention (Japanese Patent Application No. 55227/1989).
In addition, this method does not allow the adhesion of polymeric substances, commonly known as scale, inside the polymerization can, which eliminates the need to work inside the can to remove scale, improving working conditions at vinyl chloride resin manufacturing plants. .

The suspension stabilizer used in the present invention is characterized by the combined use of substances classified into three types, and is a water-soluble polymer (5% ) does not require surface activity, and the surface tension of a 0.05% aqueous solution at 25°C is 55%.
dyne/CTn or higher, D-mannose, D-
Glucose, D-glucuronic acid, D-galactose, D
- Microbial polysaccharide with constituent sugars such as mannuronic acid and D-xylose, general formula X-(CH2CH2O)n-Y (wherein X, .Y are hydrogen, hydroxyl group, alkyl group,
A compound represented by a hydroxyalkyl group or a polypropylene oxide group (n is an integer of 20,000 or more), especially polyethylene oxide where X is a hydroxyl group and Y is hydrogen; a maleic anhydride-methyl vinyl ether copolymer; Examples include alginic acid, alginic acid sodium salt, and propylene glycol ester of alginic acid.

It is characterized in that it is effective in an amount of 0.005 to 0.0001 parts to be used in an aqueous medium. If the amount added is less than 0.0001 part, the effect of reducing CM remaining in the vinyl chloride resin is small, and even if it is added in excess of 0.005 part, the reducing effect is saturated, resulting in a cost disadvantage.

The surface tension of a 0.05% aqueous solution at 25°C is 55
Examples of the water-soluble polymer (B) having a dyr1e/CWL or lower are partially saponified polyvinyl acetate with a saponification degree of 82 mol% or less, methylcellulose, and especially hydroxypropoxy group-containing with a methoxy group content of 20% by weight or more. Methyl cellulose in an amount of 4% by weight or more, etc.

The amount used is 0.1 to 0.01 part based on the aqueous medium, and 0.
．． If it exceeds 1 part, the number of emulsion particles increases rapidly and the required suspended particle size cannot be obtained due to the large amount of fine powder, while if it is less than 0.01 part, suspension stability is lacking and the polymerization process becomes agglomerated during polymerization, making the polymerization operation impossible. The surface tension of a 0.1% aqueous solution at 30°C is 5
5d37ne/CT! Low molecular weight nonionic surfactants of 1 or less (0 is exemplified as HLB (HydrO
Nonionic surfactants with a philicllpOphilic balance) of 5 to 20 and an average molecular weight of 10,000 or less, such as polyoxyethylene alkyl ether (alkyl groups include oleyl, cetyl, stearyl, lauryl, dodecyl, etc.), polyoxyethylene Nonylphenyl ether, polyoxyethylene octylphenyl ether, mono- or diester of saturated or unsaturated fatty acid and polyethylene oxide, sorbitan alkyl ester, polyethylene oxide adduct of sorbitan alkyl ester, ethylene oxide-propylene oxide block, etc. Polymers, etc. are listed.

The amount of nonionic surfactant is 0.1 to 0.01 relative to VCM.
It is characterized by being a department. If it exceeds 0.1 part, it is not preferable because it causes discoloration of the molded product and scattering of slurry due to foaming during recovery of unpolymerized VCM.

If it is less than 0.01 part, no residual CM reducing effect is observed.

Note that any number of these three types may be used in combination. Examples of vinyl monomers that can be copolymerized with CM include known monomers such as vinyl acetate, maleic acid, itaconic acid, vinylidene chloride, ethylene, and propylene.

The oil-soluble radical initiators used in the present invention include azo compounds such as azobisisobutylnitrile and azobis2,4-dimethylvaleronitrile, lauroyl peroxide, t-butyl pivalate, di,2-ethylhexyl peroxydicarbonate, and diisopropyl peroxide. Known initiators include organic peroxides such as oxydicarbonate. Furthermore, in the suspension polymerization of the present invention, mercaptan, disulfide, trichloroethylene, etc. as polymerization degree regulators are added, and alcohols, saturated hydrocarbons, aromatics such as benzene, toluene, etc., DOP, epoxy soybean oil, etc. are added as additives. There is no hindrance to using drugs together. Suspension polymerization is carried out in the presence of the above-mentioned raw materials and additives, at a polymer conversion rate of 80-90%, and on the basis of the drop in pressure inside the can at the designed conversion rate, unpolymerized VCM is heated to atmospheric pressure at the gas pressure of VCM. The unpolymerized VCM remaining in the slurry is removed under reduced pressure at a temperature above the polymerization temperature using a vacuum pump, and is liquefied and recovered.

The suspension polymerization method of the present invention provides suspension polymer particles that enhance the recovery and removal efficiency.In the conventional suspension polymerization method, the VCM contained in the vinyl chloride resin in the slurry discharged from the polymerization can was 1000 ppm. However, according to the present invention, it becomes 30 ppm or less. Subsequently, the slurry discharged from the polymerization can is dehydrated and dried in a flash dryer, rotary dryer, or fluidized fluid dryer, abnormal particles are sieved, and the residual VCM in the resulting vinyl chloride resin product is In the legal case, it was 100 ppm or more, but in the case of the present invention, it was 1 ppm.
m or less.

Accordingly, according to the present invention, the amount of VCM exhausted in a vinyl chloride manufacturing factory will be reduced to 1/30 or less, and the amount of residual CM in the vinyl chloride resin product after drying will be reduced to 1/100 or less, and the amount of CM exhausted during the molding process will be reduced to 1/100 or less. This is an innovative suspension polymerization method that allows the amount of VCM to be reduced to 1/100 or less. The present invention is characterized by the combined use of all three types (B) (O), and the absence of any one type will result in disadvantages.
(The effect of reducing residual CM in the polymer obtained by combining 8 and (B) is smaller than that of the present invention, and the combination of (8) and (0) is more effective than the combination of (A) and (B). The effect is even smaller (4
) and (0) in combination lacks suspension stability.Examples will be shown for more specific explanation, but these are not intended to limit the scope of the present invention.

Example 4% by weight in a stainless steel polymerization machine of 120001
Absolute viscosity of aqueous solution at 20°C is 35 cps and 0.0
Partially saponified polyvinyl acetate 4007 with a surface tension of 51 dyne/CTL in a 5% aqueous solution and polyethylene oxide 307 with a specific viscosity of 0.2 at 60°C in a 0.01% aqueous solution and 307 in a 0.1% by weight aqueous solution at 30°C. 1000 kg of demineralized water in which 150 f of polyoxyethylene nonyl phenyl ether (molecular weight 1981) having a surface tension of 47.2 dyne/CfL and an HLB of 17.8 was dissolved.
After adding 1257 g of initiator di-2-ethylhexyl peroxydicarbonate and degassing with a vacuum pump, 500 kg of vinyl chloride monomer (VCM) was added and the internal temperature was 58°C.
The polymerization pressure is 1kg/Cd lower than the steady pressure during polymerization.
When the temperature decreased, unpolymerized VCM was collected, and the CM was further collected and removed under reduced pressure at a slurry temperature of 60°C for 30 minutes, and the slurry was discharged.

Subsequently, the slurry was dehydrated and dried in a fluidized bed at 55°C in a fluidized dryer.
After drying for 1 hour, a vinyl chloride resin having a moisture content of 0.3% was obtained.

Example 2 As a suspension stabilizer, partially saponified polyvinyl acetate 4007 described in Example 1 and methyl vinyl ether-maleic anhydride copolymer 5V having a specific viscosity of 1.2 at 60°C in a 0.01% by weight aqueous solution were used. 100 ml of demineralized water containing 50 t of polyoxyethylene nonyl phenyl ether as described in Example 1
0 kg was charged into a 20001 stainless steel polymerization can, and the other conditions were the same as in Example 1 to obtain a vinyl chloride resin.

Example 3 As a suspension stabilizer, a 2% by weight aqueous solution with a viscosity of 100 cps at 20°C and a methoxy group content of 21%,
1000 kg of demineralized water in which methylcellulose 350V with a hydroxypropoxy group content of 6.2%, polyethylene oxide 207 described in Example 1, and polyoxyethylene nonyl phenyl ether 507 described in Example 1 were dissolved.
was charged, 22'-azobis2,4-dimethylvalenitrile 1757 was added as an initiator, and the subsequent operations were carried out in the same manner as in Example 1 to obtain a vinyl chloride resin.

Example 4 Surface tension at 30°C of a 0.1% by weight aqueous solution of partially saponified polyvinyl acetate 400f described in Example 1 as a suspension stabilizer and methyl vinyl ether-maleic anhydride copolymer 57 described in Example 2. 47dyne/C7rL'('
1000 k9 of demineralized water in which 507 ethylene oxide propylene oxide block copolymer (molecular weight 2500) having an HLB of 6.0 (molecular weight 2500) was dissolved was charged, and the rest was carried out in the same manner as in Example 1 to obtain a vinyl chloride resin.

Example 5 Instead of polyoxyethylene nonyl phenyl ether 50f in Example 2, the surface tension of a 0.1% by weight aqueous solution at 30°C was 51.5 dyne/C7! After adding 507 liters of polyoxyethylene monostearate (molecular weight 2044), a vinyl chloride resin was obtained in accordance with Example 2.

Comparative Example 1 Partially saponified polyvinyl acetate 40 from the suspension stabilizer of Example 1
The same operation as in Example 1 was performed except for 07.

Comparative Example 2 The same operation as in Example 1 was carried out except that polyoxyethylene nonyl phenyl ether was removed from the suspension stabilizer in Example 1.

Comparative Example 3 Partially saponified polyvinyl acetate 40 from the suspension stabilizer of Example 2
The same operation as in Example 2 was performed except for 07.

Comparative Example 4 The same operation as in Example 2 was carried out except that polyoxyethylene nonyl phenyl ether was removed from the suspension stabilizer in Example 2.

Comparative Example 5 The same operation as in Example 3 was carried out except that polyoxyethylene nonyl phenyl ether was removed from the suspension stabilizer of Example 3.

Comparative Example 6 The same operation as in Example 1 was carried out except that polyethylene oxide and polyoxyethylene nonyl phenyl ether were removed from the suspension stabilizer of Example 1.

Table 1 shows the CM concentration contained in the vinyl chloride resin in the waste slurry obtained according to Examples 1 to 5 and Comparative Examples 1 to 6, and the concentration contained in the dried vinyl chloride resin product.

Claims (1)

[Claims] 1. When vinyl chloride alone or a mixture with other vinyl monomers copolymerizable with vinyl chloride is subjected to suspension polymerization in an aqueous medium at 500 to 70°C using an oil-soluble radical initiator, As a suspension stabilizer, a water-soluble polymer (A) having a specific viscosity of 0.1 or more at 60°C in a 0.01% by weight aqueous solution and 0.05% by weight
The surface tension of an aqueous solution at 25°C is 55 dyne/cm
A vinyl chloride suspension characterized by using together the following water-soluble polymer (B) and 0.1% by weight of a low molecular weight nonionic surfactant (C) having a surface tension of 55 dyne/cm or less at 30°C. Turbidity polymerization method. 2. The polymerization method according to claim 1, wherein the water-soluble polymer (A) is a microbial polysaccharide. 3 Microbial polysaccharides include D-mannose, D-glucose,
The polymerization method according to claim 2, wherein D-glucuronic acid, D-galactose, D-mannuronic acid, D-xyrose, or a mixture thereof. 4 The water-soluble polymer (A) has the general formula: 2. The polymerization method according to claim 1, wherein the compound is a compound represented by (an integer). 5. The polymerization method according to claim 4, wherein X is a hydroxy group and Y is hydrogen. 6. The polymerization method according to claim 1, wherein the water-soluble polymer (A) is a copolymer of maleic anhydride-methyl vinyl ether. 7. The polymerization method according to claim 1, wherein the water-soluble polymer (A) is alginic acid, alginic acid sodium salt, or propylene glycol ester of alginic acid. 8. The polymerization method according to claim 1, wherein the water-soluble polymer (B) is partially saponified polyvinyl acetate of 82 mol% or less. 9. The polymerization method according to claim 1, wherein the water-soluble polymer (B) is methylcellulose. 10. The polymerization method according to claim 9, wherein the methyl cellulose has a methoxy group content of 20% by weight or more and a hydroxypropoxy group content of 4% by weight or more. 11 Low molecular weight nonionic surfactant (C) has HLB5~
20. The polymerization method according to claim 1, wherein the weight average molecular weight is 10,000 or less. 12. The polymerization method according to claim 1, wherein the low molecular weight nonionic surfactant (C) is polyoxyethylene alkyl ether. 13. The polymerization method according to claim 12, wherein the alkyl group is an oleyl group, cetyl group, stearyl group, lauryl group or dodecyl group. 14 Low molecular weight nonionic surfactant (C) is polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, mono or diester of saturated or unsaturated fatty acid and polyethylene oxide, sorbitan alkyl ester or polyethylene oxide addition of sorbitan alkyl ester The polymerization method according to claim 1, wherein at least one type is selected from the group consisting of ethylene oxide and ethylene oxide-propylene oxide block copolymers. 15 Water-soluble polymer (A) is 0.005 to aqueous medium
0.0001 part, water-soluble polymer (B) is 0 in the aqueous medium
．． 1 to 0.01 part, low molecular weight nonionic surfactant (C)
2. The polymerization method according to claim 1, wherein is used in an amount of 0.1 to 0.01 part based on the vinyl chloride monomer.