JPS6353202B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a vinyl chloride polymer emulsion. More specifically, the present invention relates to a method for producing a vinyl chloride polymer emulsion that is substantially or completely free from the formation of aggregates and has excellent mechanical stability, storage stability, etc. Vinyl chloride polymers have moderate flexibility, excellent water resistance, chemical resistance, weather resistance, etc., and are also flame retardant, so these polymer emulsions can be used as vehicles for various paints, and on paper, metal, and cement surfaces. It is usefully used in a variety of applications, including as a coating material for textiles, as a reinforcing admixture for cement, and as a flame retardant for spinning dope. Conventionally, it has been known to use a polyvinyl alcohol derivative having a sulfonic group or a sulfuric acid group as a dispersion medium when producing a vinyl chloride polymer emulsion (for example, Japanese Patent Publication No. 50-29948, Japanese Patent Application Laid-open No. 14589/1989) ). According to the above method, it is possible to produce a vinyl chloride polymer emulsion that has good affinity with polyvinyl alcohol, but it may produce a significantly large amount of aggregates or coarse particles of about 1 μm or more, It has a serious drawback of poor storage stability. This drawback is particularly noticeable when copolymerizing vinyl chloride monomers with other ethylenically unsaturated monomers. In view of such circumstances, the present inventors have conducted intensive studies to overcome the above-mentioned drawbacks, and as a result, the present inventors have developed a method for polymerizing vinyl chloride monomers using a polyvinyl alcohol derivative having a sulfonic group or a sulfuric acid group as a dispersion medium. The present inventors have discovered that the presence of a specific inorganic salt in the polymerization system, and the combined use of a specific inorganic salt and a nonionic surfactant, are effective in eliminating the above drawbacks, leading to the present invention. That is, the present invention provides a method for combining vinyl chloride monomer alone or a mixture of vinyl chloride monomer and other ethylenically unsaturated monomer copolymerizable with polyvinyl alcohol having a sulfonic group or sulfuric acid group and a water-soluble In the production of a vinyl chloride polymer emulsion by polymerization in the presence of a catalyst, in the presence of at least one inorganic salt selected from alkali metal or ammonium sulfates, hydrochlorides, carbonates, bicarbonates, and phosphates. It is an object of the present invention to provide a method for producing a vinyl chloride polymer emulsion, which is characterized by the fact that it undergoes polymerization in a manner that extremely little formation of aggregates or coarse particles occurs, and which has excellent mechanical stability, storage stability, etc. The inorganic salt used in the method of the present invention is used to effectively suppress the formation of aggregates and to produce an emulsion with few coarse particles and excellent storage stability and mechanical stability. be. However, in the conventional polymerization using polyvinyl alcohol having a sulfone group or a sulfate group as a dispersion medium, it was unavoidable to produce an extremely large amount of aggregates and coarse particles, so such an effect was completely unexpected. That's true. Inorganic salts used in the method of the present invention include alkali metal or ammonium sulfates, hydrochlorides,
It is selected from carbonates, bicarbonates and phosphates. Examples of such inorganic salts include sodium sulfate, potassium sulfate, sodium chloride, potassium chloride, sodium carbonate, sodium bicarbonate, sodium phosphate, sodium hydrogen phosphate, ammonium sulfate, ammonium chloride, and the like. Particularly preferred is sodium sulfate. These inorganic salts can be used alone or in combination. The amount of inorganic salt added to the polymerization system varies depending on the type of monomer to be polymerized and its proportion, but it is usually 0.05 to 1% by weight, especially 0.15 to 1% by weight based on the total monomers charged.
Selected from a range of 0.8% by weight. If the amount added is less than 0.05% by weight, the effect of preventing the formation of aggregates and improving the mechanical stability and storage stability of the emulsion will be slight, while if it exceeds 1% by weight, coarse particles will increase and be formed. This is not preferable because the storage stability of the emulsion is reduced. The polyvinyl alcohol derivative having a sulfonic group or a sulfuric acid group used in carrying out the method of the present invention is used to provide a vinyl chloride polymer emulsion having excellent mechanical stability and storage stability. A polyvinyl alcohol derivative having a sulfone group or a sulfuric acid group refers to -SO ₃ M or - in the side chain.
It is a polyvinyl alcohol having OSO ₃ M (M represents sodium, potassium atom or ammonium). Such polyvinyl alcohol derivatives having a sulfonic group or a sulfuric acid group include, for example, polymerizable α, β-unsaturated sulfonic acids such as vinyl sulfonic acid, allyl sulfonic acid, styrene sulfonic acid, or salts thereof and vinyl acetate. It is produced by a method such as saponification and neutralization after polymerization, or sulfonation or sulfate esterification of polyvinyl alcohol and then neutralization with alkali. Usually the content of sulfonic or sulfate groups is 0.5
~10 mol% polyvinyl alcohol derivative is used. The amount of the polyvinyl alcohol derivative having a sulfonic group or sulfuric acid group varies depending on the type of monomer to be polymerized, the type and amount of the inorganic salt to be added, etc., but it is usually 0.5 to 5% based on the total monomers charged. weight%
In particular, it may be used in an amount of 1 to 4% by weight. Furthermore, when carrying out the method of the present invention, in addition to the use of the above-mentioned inorganic salt, the presence of a nonionic surfactant in the polymerization system can more effectively prevent the formation of aggregates and prevent the emulsion from forming. It is more preferable because it improves the mechanical stability, storage stability, and chemical stability of. Such nonionic surfactants have a hydrophilic-lipophilic balance (hereinafter referred to as HLB) of 15.5.
~18.5 polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl ether,
Examples include polyoxyethylene fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene-polyoxypropylene block copolymer, etc., and these can be used alone or in combination. Among these, nonionic surfactants with HLB16-18 are particularly preferably used. The HLB of the nonionic surfactant used is
When the HLB is less than 15.5, the effect of preventing the formation of aggregates and the improvement in the storage stability of the emulsion cannot be achieved, and when the HLB exceeds 18.5, the mechanical stability of the emulsion decreases, which is not preferable. The amount of nonionic surfactant added to the polymerization system is 0.5 to 5% by weight, especially 1 to 5% by weight based on the total monomers charged.
It is in the range of 3% by weight. If the amount added is less than 0.5% by weight, the effect of preventing the formation of aggregates will be lost, while if it exceeds 5% by weight, the resulting emulsion will foam violently and the water resistance of the film will decrease, which is not preferable. The monomers used in carrying out the method of the present invention are:
It is selected from vinyl chloride monomers or mixtures of vinyl chloride monomers and other ethylenically unsaturated monomers copolymerizable with vinyl chloride monomers. Other ethylenically unsaturated monomers that can be copolymerized with vinyl chloride include alkyl esters of α,β-unsaturated carboxylic acids, fatty acid vinyl esters, aromatic vinyl, acrylamide and its derivatives, acrylonitrile and its derivatives, and chloride. Examples include halogenated vinyl other than vinyl, olefin, and the like. By the way, when using vinyl chloride-based polymer emulsions for applications that require film-forming properties such as paints, coating agents for paper and metal, admixtures for cement, and anti-slip coatings for cement, it is necessary to from 30 to 70% by weight, preferably from 40 to 65% by weight, and at least one selected from alkyl esters of α,β-unsaturated carboxylic acids (excluding methyl methacrylate) and fatty acid vinyl esters.
It is desirable to form a copolymer emulsion containing 70 to 30% by weight of the seed monomer, preferably 60 to 35% by weight. If the proportion of vinyl chloride monomer exceeds 70% by weight, the film will become hard and brittle, and the film forming properties of the emulsion will be poor, while if it is less than 30% by weight, the film will have poor water resistance and chemical resistance. It became like this,
This makes it unsuitable for the above-mentioned applications. Examples of the alkyl esters of the above α,β-unsaturated carboxylic acids (excluding methyl methacrylate) include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, octyl acrylate, and lauryl acrylate. Acrylic acid alkyl esters having 1 to 16 carbon atoms, especially 4 to 12 alkyl groups, such as; ethyl methacrylate, propyl methacrylate,
Methacrylic acid alkyl esters having 1 to 16 carbon atoms, especially 4 to 12 alkyl groups, such as butyl methacrylate, hexyl methacrylate, octyl methacrylate, lauryl methacrylate; dimethyl maleate, diethyl maleate, dibutyl maleate, Dioctyl maleate, dilauryl maleate, etc. having 1 to 16 carbon atoms, especially 4 to 16 carbon atoms
Maleic acid dialkyl ester having 12 alkyl groups; having an alkyl group of 1 to 16 carbon atoms, especially 4 to 12 carbon atoms, such as dimethyl fumarate, diethyl fumarate, dibutyl fumarate, dioctyl fumarate, dilauryl fumarate, etc. Dialkyl fumarate; 1 to 16 carbon atoms, especially 4 carbon atoms, such as diethyl itaconate, dibutyl itaconate, dihexyl itaconate, dioctyl itaconate, dilauryl itaconate, etc.
Examples include dialkyl itaconic acid esters having ~12 alkyl groups. Examples of fatty acid vinyl esters include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl laurate, vinyl caproate, vinyl stearate, vinyl palmitate, vinyl versatate, etc. having 1 to 16 carbon atoms, especially 1 to 4 carbon atoms. Examples include vinyl esters of fatty acids having . Particularly preferably 30 to 70% by weight of vinyl chloride monomer;
Alkyl esters of α,β-unsaturated carboxylic acids 50
~25% by weight and fatty acid vinyl ester 20-3% by weight. As the water-soluble catalyst used in carrying out the method of the present invention, all catalysts used in the polymerization of vinyl chloride can be used, and more specifically, hydrogen peroxide, potassium persulfate, ammonium persulfate, etc. and, for example, sodium bisulfite, sodium thiosulfate,
A combination system with a suitable reducing agent such as sodium pyrosulfite or Rongarit can be used. The amount of catalyst used is approximately
0.003-2% by weight is commonly used. In carrying out the method of the present invention, the monomers can be added all at once, in portions, or continuously. Particularly when alkyl esters of acrylic acid or methacrylic acid are used as a comonomer, it is desirable to add them in portions or continuously to form a copolymer with a uniform composition. In carrying out the process of the invention, the polymerization generally ranges from about 30 to
It is carried out in a temperature range of 80℃. The vinyl chloride polymer emulsion produced in this way is substantially or completely free of aggregates and has excellent mechanical stability and storage stability, so it can be used as spinning dope, paint vehicle, paper, metal, etc. It is useful for applications such as coating agents, cement admixtures, and anti-slip coatings for cement. When applying to these uses, plasticizers,
Coating aids, pigments, fillers, cement, etc. can be added in arbitrary amounts as needed. According to the method of the present invention as detailed above, in polymerization using polyvinyl alcohol having a sulfonic group or a sulfuric acid group as a dispersion medium, formation of aggregates can be prevented, and mechanical stability, storage stability, A vinyl chloride polymer emulsion with excellent chemical stability can be produced. In particular, in the copolymerization of vinyl chloride monomers and ethylenically unsaturated monomers, the formation of aggregates and coarse particles is remarkable, but the method of the present invention exhibits remarkable effects in such copolymerization systems. do. Hereinafter, the method of the present invention will be explained in more detail with reference to Examples, but the method of the present invention is not limited thereto. The physical properties of the emulsion and film were measured by the following method. Solid content concentration: Method 4.2 of JIS K6828-1964. Average particle size: Electron microscopy Mechanical stability: The emulsion was stirred with a Hamilton Beach mixer at 13,000 rpm for 30 minutes, and the resulting aggregates were separately dried on a 100-mesh wire mesh, and expressed as weight % based on the resin content. If the entire emulsion coagulated and solidified within 30 minutes, the time until then was shown. Storage stability: When the emulsion was left at 50°C for 2 weeks, the sediment was collected, dried, and expressed as weight % based on the resin content. Chemical stability: Mix and stir 20% by weight/resin of aluminum sulfate in an emulsion prepared by adding ion-exchanged water to a solid concentration of 5%, let stand for 1 hour, and dry the aggregate separately on a 100-mesh wire mesh. It is expressed in weight % based on the resin content. Water resistance: The weight increase rate of the film obtained by drying at 20°C was immersed in water at 20°C for 7 days. Alkali resistance: The film obtained by drying at 20℃
It is expressed as the weight increase rate of the film when immersed in a 10% caustic soda aqueous solution at ℃ for 7 days. Example 1 100 ml of ion-exchanged water in an autoclave,
15g potassium persulfate, sodium hydrogen phosphate
After charging 120 g of a polyvinyl alcohol derivative having a degree of saponification of 98 mol % and containing 2 mol % of sodium sulfonate, it was degassed, and then 30 kg of vinyl chloride monomer was charged. Next, while stirring, the mixture was heated to 65°C and polymerized for 6 hours. After the polymerization was completed, the contents were filtered through a 100-mesh wire gauze, and the proportion of aggregates and the physical properties of the resulting emulsion were measured. The results are shown in Table 1. For comparison, polymerization was carried out in exactly the same manner as above except that anhydrous sodium sulfate was not used. The results are also shown in Table 1.

[Table] From Table 1, it can be seen that the method of the present invention produces significantly less aggregates than the conventionally known method, and also has fewer coarse particles, so it has improved storage stability and mechanical stability. it is obvious. Example 2 100 ml of ion-exchanged water in an autoclave,
Potassium persulfate 60g, anhydrous sodium sulfate 120g,
Saponification degree 98 mol% containing 600 g of polyoxyethylene nonyl phenyl ether of HLB of the type shown in Table 2 and 2 mol% of sodium sulfonate
Since 600 g of polyvinyl alcohol derivative was charged, it was degassed, and then 30 kg of vinyl chloride monomer was charged. Next, the mixture was heated to 50° C. while stirring, and polymerization was carried out for 14 hours. After the polymerization was completed, the contents were filtered through a 100-mesh wire gauze, and the proportion of aggregates and the physical properties of the resulting emulsion were measured. The results are shown in Table 2.

[Table] From Table 2, the amount of aggregates formed can be significantly suppressed by using polyvinyl alcohol having a sulfone group or sulfate group as an emulsifier together with a nonionic surfactant having a specific HLB. Moreover, it is clear that mechanical stability and storage stability can be significantly improved. Example 3 100 autoclave, ion exchange water 35,
Potassium persulfate 175g, anhydrous sodium sulfate 140g
and a polyvinyl alcohol derivative with a saponification degree of 98 mol% containing 2 mol% of sodium sulfonate.
I loaded 1.4Kg. After deaerating the autocube, 15.7 kg of vinyl chloride and 3.5 kg of vinyl acetate were removed.
I loaded Kg. Heat to 50°C with stirring. At the same time as heating started, 2-ethylhexyl acrylate was supplied at a rate of 1.6 kg/hour for 10 hours.
Polymerization was carried out for 14 hours. After the polymerization was completed, the contents were filtered through a 100-mesh wire gauze, and the proportion of aggregates and the physical properties of the resulting emulsion were measured. For comparison, polymerization was performed in the same manner as above except that anhydrous sodium sulfate was not used (Comparative Example 2), and polymerization was performed in the same manner as above except that 1.4 kg of sodium dodecy-4benzenesulfonate was used instead of the polyvinyl alcohol derivative. Polymerization (Comparative Example 3) was carried out. The above results are shown in Table 3.

[Table] Table 3 shows that the method of the present invention significantly suppresses the amount of aggregates produced compared to conventionally known methods, and also improves mechanical stability, storage stability, and chemical stability. It is clear that the film produced from the emulsion has excellent water resistance and alkali resistance. Example 4 In Example 3, polyvinyl alcohol with a saponification degree of 98 mol% containing a nonionic surfactant of the type and amount shown in Table 4 and 2 mol% of sodium sulfonate in the amount shown in Table 4 as an emulsifier. Polymerization was carried out in the same manner as in Example 3 except that the derivative was used. The results are shown in Table 4.

[Table] Example 5 Experiment No. 12 except that in the method of Example 4, Experiment No. 10, the type and amount of inorganic salt shown in Table 5 was used.
Polymerization was carried out in the same manner. The results are shown in Table 5.

[Table] Example 6 35 ion-exchanged water, 175 g of potassium persulfate, 175 g of anhydrous sodium sulfate in a 100 autoclave,
Polyoxyethylene nonyl ether with HLB17.2
700 g and 875 g of a polyvinyl alcohol derivative having a degree of saponification of 98 mol % and containing 2 mol % sodium sulfonate were charged. Next, after degassing the inside of the autoclave, monomers of the type and amount shown in Table 6 were charged and heated to 50° C. with stirring. Also※
The monomer indicated by the mark is approximately 10
It was added continuously over time. Autoclave internal pressure is 0.3
When the temperature reached Kg/cm ² G, the temperature was raised to 70°C and further 1
After polymerization for an hour, it was discarded. Thereafter, physical properties were measured in the same manner as in Example 1. The results are shown in Table 6. In addition, the monomer ( )
The numerical value indicates the supply ratio (wt%).

【table】

[Table] From Tables 4, 5, and 6, the method of the present invention can significantly suppress the amount of aggregates produced, and has excellent mechanical stability, chemical stability, and storage stability. It is clear that a highly concentrated emulsion is obtained. In particular, vinyl chloride monomer 30-70% by weight, α, β
- alkyl esters of unsaturated carboxylic acids (provided that
At least one monomer selected from (excluding methyl methacrylate) and fatty acid vinyl esters70
It is clear that in the case of copolymer emulsions of up to 30% by weight, the process of the present invention exhibits remarkable effects and provides films with excellent water and alkali resistance.

Claims (1)

[Scope of Claims] 1 Vinyl chloride monomer alone or a mixture of vinyl chloride monomer and other ethylenically unsaturated monomers copolymerizable therewith with polyvinyl alcohol having a sulfonic group or sulfuric acid group and a water-soluble At least one inorganic salt selected from alkali metal or ammonium sulfates, hydrochlorides, carbonates, bicarbonates, and phosphates is polymerized in the presence of a neutral catalyst to produce a vinyl chloride polymer emulsion. 1. A method for producing a vinyl chloride polymer emulsion, the method comprising carrying out polymerization in the presence of a vinyl chloride polymer. 2 The amount of inorganic salt added is based on the total monomer content.
The method for producing a vinyl chloride polymer emulsion according to claim 1, characterized in that the amount is 0.05 to 1% by weight. 3 alkali metal or ammonium sulfates,
The polymerization is carried out in the presence of at least one inorganic salt selected from hydrochloride, carbonate, bicarbonate and phosphate and a nonionic surfactant having a hydrophilic-lipophilic balance of 15.5 to 18.5. A method for producing a vinyl chloride polymer emulsion according to claim 1. 4 A vinyl chloride polymer is obtained by polymerizing a mixture of vinyl chloride monomer and other ethylenically unsaturated monomers copolymerizable with it in the presence of polyvinyl alcohol having a sulfonic group or sulfuric acid group and a water-soluble catalyst. In producing the emulsion, 30 to 70% by weight of vinyl chloride monomer and at least one monomer selected from alkyl esters of α/β-unsaturated carboxylic acids (excluding methyl methacrylate) and fatty acid vinyl esters are used. mixture with 70-30% by weight of alkali metal or ammonium sulfates,
The vinyl chloride polymer emulsion according to claim 1, wherein the polymerization is carried out in the presence of at least one inorganic salt selected from hydrochloride, carbonate, bicarbonate, and phosphate. manufacturing method. 5 The amount of inorganic salt added is based on the total monomer content.
5. The method for producing a vinyl chloride copolymer emulsion according to claim 4, characterized in that the amount is 0.05 to 1% by weight. 6 alkali metal or ammonium sulfates,
Polymerization is carried out in the presence of at least one inorganic salt selected from hydrochloride, carbonate, bicarbonate, and phosphate and a nonionic surfactant having a hydrophilic group/lipophilic group balance of 15.5 to 18.5. A method for producing a vinyl chloride copolymer emulsion according to claim 4, characterized in that: