JPH0146174B2 - - Google Patents

Description

[Detailed description of the invention]

In emulsion polymerization of unsaturated monomers such as acrylic esters and vinyl acetate, various nonionic or anionic surfactants have traditionally been used alone or in combination as emulsifiers, and in some cases, polyvinyl alcohol has been used as an emulsifier. Protective colloid agents such as PVA are used. The emulsion obtained by such a method is an adhesive,
Although it is extremely useful as a coating agent, fiber processing agent, etc., it has drawbacks such as poor storage stability, freeze-thaw stability, and dilution stability. As one of the countermeasures, it has been proposed to use a copolymer of an olefin sulfonate such as ethylene sulfonate or allyl sulfonate and vinyl acetate, or a saponified product thereof, as an emulsifier. As a result of their investigation, it was found that when such emulsifiers are used, the above-mentioned difficulties are significantly improved, but there is a problem in that it is difficult to obtain emulsions with high viscosity. In the case of a low-viscosity emulsion, if the emulsion is applied to a porous substrate such as paper or cloth, the emulsion will penetrate into the interior of the substrate and the yield on the surface of the substrate will decrease, so it will not be possible to achieve the desired coating film. This may cause problems such as physical properties not being fully exhibited. To avoid this, it is possible to add a thickener to the emulsion, but
Extreme care must be taken to avoid problems such as phase separation with the emulsion and destruction of the emulsion, which is not necessarily advantageous in practice, and there is a need for the development of an emulsifier that makes it possible to produce emulsions with high viscosity. However, as a result of intensive research to satisfy this request, the present inventors found that vinyl ester and the general formula CH ₂ = CR ₁ · CONH · R ₂ · SO ₃ M (herein,
R ₁ ; hydrogen, methyl group, R ₂ ; alkylene group, M;
Either the unsaturated monomer is emulsion polymerized in an aqueous medium using a copolymer with N-sulfoalkyl (meth)acrylamide represented by hydrogen or an alkali metal as an emulsifier, or the unsaturated monomer is polymerized in an aqueous medium. When the above-mentioned copolymer is added to an aqueous emulsion obtained by emulsion polymerization of When producing an emulsion, it is possible to produce a highly viscous aqueous emulsion, and the resulting emulsion has remarkable effects such as good performance in terms of storage stability, freeze-thaw stability, and dilution stability. The present invention was completed based on this discovery. That is, in the present invention, when an acrylic ester is emulsion polymerized using the above copolymer as an emulsifier, an emulsion with a higher viscosity is produced than when using a conventional olefin sulfonate/vinyl acetate copolymer or a saponified product thereof. At the same time, the resulting emulsion has excellent storage stability, freeze-thaw stability, dilution stability, etc., which is equivalent to or better than when using olefin sulfonate/vinyl acetate copolymer or its saponified product. The industrial utility of the present invention is very great because of the excellent performance. In the N-sulfoalkyl (meth)acrylamide in the copolymer component, the alkylene group (R ₂ ) may be an ethylene group, a propylene group, a butylene group, etc., and may be either linear or branched, but the stability of the amide bond is important. Those containing a branched alkylene group are preferred. Further, M is hydrogen or an alkali metal, but free sulfonic acid (M is hydrogen) may decompose vinyl esters during copolymerization, so an alkali metal such as sodium or potassium is usually preferable. Among such acrylamides, N-sulfoisobutylene acrylamide sodium salt is used in the present invention.

[Formula] is particularly preferably used. Examples of the vinyl ester include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl valerate, vinyl caproate, vinyl versatate, etc., and vinyl acetate is preferably used. The ratio of each component is not particularly limited and any ratio can be selected, but N-sulfoalkyl (meth)acrylamide is 1 to 20 mol%, preferably 3 to 20 mol%, vinyl ester is 80 to 99 mol%, Preferably
A range of 80 to 97 mol% is suitable. The ratio of N-sulfoalkyl (meth)acrylamide is 1 mol%
If it is less than 20 mol %, it is difficult to obtain the effect of the present application, and on the other hand, if it is more than 20 mol %, a good emulsion cannot be produced. In producing the above copolymer, N-sulfoalkyl (meth)acrylamide and vinyl ester are copolymerized in an alcohol solvent. Alcohols include methanol, ethanol,
Lower alcohols such as propanol are commonly used. These alcohols may contain a small amount of water. There are no particular restrictions on the method of charging monomers during polymerization, and any method such as batch charging, split charging, continuous charging, etc. can be adopted, but N
- From the viewpoint of the copolymerization ratio of sulfoalkyl (meth)acrylamide and vinyl ester, the vinyl ester is first dissolved in an alcohol solvent, and the above (meth)acrylamide is added dropwise to polymerize to obtain a copolymer with a uniform composition. It is easy to obtain and advantageous. In the copolymerization, known radical polymerization catalysts such as azobisisobutyronitrile, acetyl peroxide, benzoyl peroxide, and lauroyl peroxide are used. The polymerization temperature is preferably about 50°C to the boiling point. In addition, in carrying out such polymerization, other unsaturated monomers that can be copolymerized with these monomers other than the above two components, such as styrene, alkyl vinyl ether, (meth)acrylamide, ethylene, propylene, α-hexene, etc. , olefins such as α-octene, unsaturated acids such as (meth)acrylic acid, crotonic acid, (anhydrous) maleic acid, fumaric acid, itaconic acid, and their alkyl esters, alkali salts, (meth)
It is also possible to include substituted alkyl esters of acrylic acid such as 2-hydroxyethyl, dimethylaminoethyl, glycidyl, and tetrahydrofurfuryl in an amount of about 10 mol % or less. Among the copolymers described above, vinyl acetate-N-sulfoisobutylene acrylamide copolymer sodium salt is preferably used in the present invention, but among such copolymers, those with a high degree of polymerization, that is, their intrinsic viscosity [η ] is 0.4 dl/g or more [However, the vinyl acetate component of the copolymer is completely saponified, and the vinyl alcohol-N-sulfoisobutylene acrylamide copolymer sodium salt is dissolved in a 0.1 N aqueous sodium hydroxide solution at 30°C. The effect is particularly remarkable when using a copolymer of the following. Such a high polymerization degree sulfonic acid group-containing vinyl ester polymer has never been produced before. For example, this is due to a decrease in the degree of polymerization during copolymerization of olefin sulfonates and vinyl esters, or because a medium with sufficient dissolution ability for the monomer has not been found. In order to produce it, the amount of sulfonic acid groups introduced would have to be significantly reduced, and the modification effect of the vinyl ester polymer would not be achieved at all.On the other hand, in order to achieve the modification effect, the amount of sulfonic acid groups introduced would have to be increased. This is because the degree of polymerization would drop markedly, making it impossible to obtain a product that could be put to practical use, and it was actually very difficult to produce a copolymer with the performance of the present invention. On the other hand, N-sulfoisobutylene acrylamide sodium salt, vinyl acetate, and vinyl acetate-N-sulfoisobutylene acrylamide copolymer sodium salt used in the present invention all exhibit good solubility in alcohol solvents such as methanol. The above-mentioned copolymers can be produced very easily industrially, and copolymers with a high degree of polymerization can be easily obtained by simply adjusting the amount of solvent used. When carrying out emulsion polymerization of unsaturated monomers using the copolymer obtained by the above method as an emulsifier, the unsaturated monomers are temporarily or continuously added in the presence of water, an emulsifier, and a polymerization catalyst. Any conventional emulsion polymerization method can be carried out, such as adding the polymer to the liquid, heating, and stirring. The amount of emulsifier used varies somewhat depending on the type of emulsifier, the resin content of the emulsion required, etc., but is usually selected from a range of about 1 to 8% by weight based on the entire emulsion polymerization reaction system. As a polymerization catalyst, potassium persulfate, ammonium persulfate, etc. are used alone or in combination with acidic sodium sulfite, and hydrogen peroxide-tartaric acid, hydrogen peroxide-iron salt, hydrogen peroxide-ascorbic acid-
Iron salts, hydrogen peroxide - Rongarit, hydrogen peroxide -
Redox catalysts such as Rongarit iron salts are used. In addition, although the above-mentioned copolymers alone can produce the remarkable effects described above, they can also be used with polyoxyethylene-alkyl ether type, polyoxyethylene-alkylphenol type, polyoxyethylene-polyhydric alcohol ester type, and polyhydric alcohol. Esters with fatty acids, nonionic activators such as oxyethylene/oxypropylene block polymers, various PVA and PVA derivatives known as emulsifiers and protective colloids, higher alcohol sulfates, higher fatty acid alkali salts, polyoxyethylene Anionic activators such as alkyl phenol ether sulfates, alkylbenzene sulfonates, naphthalene sulfonate formalin condensates, alkyl diphenyl ether sulfonates, dialkyl sulfosuccinates, higher alcohol phosphate ester salts, etc. can also be used in combination. . In particular, such surfactants can be used alone or in combination, but in the present invention, the emulsion produced has significantly less coagulum and coarse particles than when the above copolymer is used alone, and In practical terms, it is advantageous to use the copolymer and a surfactant in combination because it exhibits more remarkable performance in terms of fluidity. When using the above copolymer and surfactant together, the mixing ratio is copolymer/surfactant = 20/1 to 1/20.
(weight ratio) is appropriate. These do not necessarily need to be used in a mixed manner, and any method such as using one component at the beginning of polymerization and adding other components during the polymerization is possible. Furthermore, plasticizers such as phthalate esters and phosphate esters, and PH regulators such as sodium carbonate, sodium acetate, and sodium phosphate may also be used in combination. Examples of unsaturated monomers to be subjected to emulsion polymerization include ethylenically unsaturated monomers and butadiene monomers. Examples of the ethylenically unsaturated monomer include vinyl acetate, acrylic ester, methacrylic ester, vinyl chloride, vinylidene chloride, acrylonitrile, styrene, ethylene, etc., and homopolymerization or copolymerization of these monomers can be carried out. In particular, when acrylic monomers such as acrylic esters or methacrylic esters are homopolymerized or copolymerized, an emulsion with particularly good mechanical stability, storage stability, pigment miscibility, etc. can be obtained. Therefore, emulsion polymerization of acrylic monomers can be carried out suitably. As a butadiene monomer, butadiene-1,
There are 3,2-methylbutadiene-1,3,2,3-dimethylbutadiene-1,3,2-chlorobutadiene-1,3, etc., and these are used alone or in combination with ethylenically unsaturated monomers. . Among these, butadiene-1,3 and styrene, butadiene-1,3 and styrene and (meth)acrylic acid, butadiene-1,3 and acrylonitrile, butadiene-1,3 and acrylonitrile and styrene, butadiene-1,3 and Preference is given to carrying out the polymerization with combinations of acrylonitrile and (meth)acrylic acid esters, butadiene-1,3 and methyl methacrylate, butadiene-1,3, methyl methacrylate and (meth)acrylic acid. Furthermore, in the present invention, unsaturated monomers are produced by emulsion polymerization of unsaturated monomers in an aqueous medium using various nonionic or anionic surfactants as emulsifiers, singly or in combination, or using various water-soluble protective colloids. By adding the above-mentioned copolymer to an aqueous emulsion, an extremely high viscosity emulsion can be obtained, similar to the aqueous emulsion produced using the copolymer as an emulsifier. Moreover, the emulsion has significantly improved storage stability, freeze-thaw stability, dilution stability, etc. In addition, when producing an emulsion using the emulsifier of the present invention by a post-emulsification method, the emulsifier is dissolved in water, and a solution or molten resin is added dropwise to the solution and stirred, or the emulsifier is dissolved in water and the resin is added dropwise to the solution or molten resin and stirred. The aqueous emulsifier solution may be added dropwise to the solution and stirred. There is no particular need for heating etc. to make an emulsion, but if necessary
All you have to do is heat it to about 45-85℃. There are no particular limitations on the substances that can be emulsified; epoxy resins, urethane resins,
Urea-formalin initial condensate, phenol-formaldehyde initial condensate, alkyd resin, ketene dimer, rosin, silicone resin, wax,
Examples include polypropylene, polyethylene, asphalt, and the like. If necessary, a nonionic activator such as a polyoxyethylene-alkyl ether type, a polyoxyethylene-alkylphenol type, a polyhydric alcohol ester type, or a cationic activator such as a higher alkyl amine salt may be used together with the resin. , any of the various surfactants used during emulsion polymerization as described above can be used. It is also possible to mix these active agents into the object to be emulsified. Furthermore, plasticizers such as phthalate esters and phosphate esters, and PH regulators such as sodium carbonate, sodium acetate, and sodium phosphate may also be used in combination. It is also possible to add a water-soluble polymer substance to the emulsion thus obtained for purposes such as thickening. The amount added is usually in the range of 5 to 500% in terms of solid content based on the emulsion. Such water-soluble polymer substances include PVA, starch,
Examples include CMC, hydroxymethylcellulose, methylcellulose, casein, etc., and these can be mixed in any form such as an aqueous solution or powder. In addition, a crosslinking agent, a waterproofing agent, a pigment, a dispersant, an antifoaming agent, and an oil agent may be appropriately mixed into the emulsion as required. Emulsions obtained using the emulsifier of the present invention are useful as paper processing agents, adhesives, paints, fiber processing agents, cosmetics, materials for civil engineering and construction, and the like. Hereinafter, the emulsifier of the present invention will be explained in more detail by giving examples. In the examples, "parts" and "%" are based on weight unless otherwise specified. Example 1 N-sulfoisobutylene acrylamide sodium salt/vinyl acetate copolymer (molar ratio 5/95, [ 4.0% of η〕0.91)
150 parts of an aqueous solution and 5 parts of a 10% aqueous solution of dibasic sodium phosphate as a pH adjuster were added, and the internal temperature was raised to 65° C. while rotating at a speed of 200 rpm. Next, 9 parts of butyl acrylate and 1.25 parts of a 4% aqueous solution of potassium persulfate.
to start emulsion polymerization. Initial polymerization was carried out for 35 minutes, and then 81 parts of butyl acrylate was continuously added dropwise over 4 hours while adjusting the internal temperature of the polymerization vessel to 70°C, and 5 parts of a 4% aqueous solution of potassium persulfate was added twice. The mixture was divided into portions and emulsion polymerization was continued. The internal temperature was kept at 75°C and the aging reaction was carried out for 1 hour, and then the remaining monomer was expelled to obtain an emulsion of butyl polyacrylate. Table 1 shows the measurement results of various properties of this emulsion. As a control example, a nonionic surfactant (manufactured by NOF Corporation, Nitsusan Nonion P-230, polyoxyethylene alkyl ether [PO-(C ₂ H ₄ O-) nH, but R; C ₁₆ H ₃₃ ,
n = 8 to 15]) 2.7 g and anionic surfactant (manufactured by Nippon Oil & Fats Co., Ltd., Nitsusan Tracks H-45,
Sodium polyoxyethylene alkyl phenyl ether sulfate [

[Formula] However, R = C _8-9 alkyl group, n < 6]) was used in combination with 0.8 g (Control Example 1), allylsulfonic acid sodium salt/vinyl acetate copolymer pair (molar ratio 3/97 [ η〕
The results of an experiment conducted in the same manner as in Example 1 except that 0.25) was used (Control Example 2) are also shown.

【table】

[Table] Example 2 Emulsion polymerization of various ethylenically unsaturated monomers was carried out according to Example 1 using emulsifiers as shown in Table 2. The results are shown in Table 2.

[Table] Example 3 A 5.7% aqueous solution of N-sulfoisobutylene acrylamide sodium salt/vinyl acetate copolymer (molar ratio 10/90, [η] 1.13) was added to the polymerization vessel of Example 1.
10 parts of a 10% aqueous solution of dibasic sodium phosphate as a PH regulator, and while rotating at a speed of 200 rpm.
The internal temperature was raised to 70°C. Next, butyl acrylate 6
1 part, 6 parts of styrene, and 3.1 parts of a 4% aqueous solution of potassium persulfate were added to start emulsion polymerization. Initial polymerization was carried out for 30 minutes, and then, while adjusting the internal temperature to 75°C, 53 parts of butyl acrylate and 53 parts of styrene were continuously added dropwise over a period of 4 hours.
% aqueous solution was added in two portions to continue emulsion polymerization. The internal temperature was maintained at 75°C and the aging reaction was carried out for 1.5 hours to obtain a butyl acrylate/styrene copolymer emulsion. The properties of this emulsion are shown in Table 3. Examples 4 to 6 In addition to the N-sulfoisobutylene acrylamide sodium salt/vinyl acetate copolymer of Example 3, 5 parts of the nonionic surfactant Nonipol 400 (manufactured by Sanyo Chemical Industries, Ltd., polyoxyethylene noniphenyl ether) was used in combination. (Example 4), the anionic surfactant eleminol was added to the copolymer of Example 3.
5 parts of MON-2 (manufactured by Sanyo Chemical Industries, Ltd., sodium alkyl diphenyl ether sulfonate) was used in combination (Example 5). 5 parts of the anionic surfactant Lebenol WZ (manufactured by Kao Soap Co., Ltd., polyoxyethylene lauryl ether) (manufactured by Kao Soap Co., Ltd., polyoxyethylene alkyl phenol ether sodium sulfate)
The same method as in Example 3 was carried out, except that 1.25 parts was used in combination (Example 6). The properties of the emulsion obtained are shown in Table 3. Example 7 An experiment was carried out in accordance with Example 6 except that N-sulfoisobutylene acrylamide sodium salt/vinyl acetate copolymer (molar ratio 25/75, [η] 1.05) was used. The results are also shown in Table 3.

【table】

【table】

Claims (1)

[Claims] 1. Vinyl ester and the general formula CH ₂ =CR ₁ .
Copolymer with N-sulfoalkyl (meth)acrylamide represented by CONH・R ₂・SO ₃ M (here, R ₁ : hydrogen, methyl group, R ₂ : alkylene group, M: hydrogen, alkali metal) An emulsifier for producing high viscosity aqueous emulsions. 2. The emulsifier according to claim 1, wherein the copolymer is vinyl acetate-N-sulfoisobutylene acrylamide copolymer sodium salt. 3 Intrinsic viscosity [η] is 0.4 dl/g or more (however, the vinyl acetate component is completely saponified to form vinyl alcohol-N-sulfoisobutylene acrylamide copolymer sodium salt, and the product is dissolved in a 0.1 N aqueous sodium hydroxide solution at 30°C. The emulsifier according to claim 2, which is a vinyl acetate-N-sulfoisobutylene acrylamide copolymer sodium salt of 4 (A) Vinyl ester and general formula CH ₂ = CR ₁・
Copolymer with N-sulfoalkyl (meth)acrylamide represented by CONH・R ₂・SO ₃ M (where R ₁ represents hydrogen, methyl group, R ₂ represents alkylene group, M represents hydrogen or alkali metal) and (B) a nonionic and/or anionic surfactant, an emulsifier for producing a high viscosity aqueous emulsion.