JPH0324254B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a dispersant comprising a crosslinked amphoteric copolymer. For more details, please refer to cosmetics, cosmetics, pharmaceuticals,
Thickeners and dispersants used in the preparation of emulsions and suspensions, especially cross-linked amphoteric agents that can stably disperse water-insoluble solid particles such as pigments, emulsifiers, water-insoluble bactericides, pearling agents, and abrasives. This invention relates to a dispersant made of a copolymer. Hitherto, various polymer electrolytes have been proposed as thickening/dispersing agents, but none have been necessarily satisfactory. For example, cross-linked polyacrylic acid is a typical example, but when used as a thickening/dispersing agent, if the system is acidic or soluble salts coexist, the viscosity decreases significantly and dispersion performance also decreases. On the other hand, in an attempt to obtain a dispersant that is effective over a wide pH range, Japanese Patent Publication No. 54-3783 proposes an amphoteric copolymer (uncrosslinked). However, the amphoteric copolymers shown therein were not necessarily fully satisfactory in systems where soluble salts were present. Therefore, the present inventors discovered that even in a wide PH range,
As a result of intensive research to obtain a polymer electrolyte that exhibits excellent thickening and dispersing effects even in systems where soluble salts coexist, we found that 45 to 55 mol% of acidic vinyl monomer or its salt and basic vinyl monomer body or its salt 45-55 mol% and crosslinkable monomer 0.05-1 mol%
By copolymerizing a mixed monomer consisting of The present invention was completed by discovering that it is possible to produce a crosslinked amphoteric copolymer that can be dispersed. The acidic vinyl monomer according to the present invention is a compound having an acidic group such as a carboxyl group or a sulfonic acid group and a polymerizable vinyl group in one molecule, such as acrylic acid, methacrylic acid, itaconic acid, etc. , maleic anhydride, 2-acrylamide-2
- Methylpropanesulfonic acid, styrenesulfonic acid, vinylsulfonic acid, allylsulfonic acid, methallylsulfonic acid, etc. can be mentioned. Also,
Examples of these salts include sodium salts, potassium salts, ammonium salts, and the like. The basic vinyl monomer according to the present invention is a compound having a basic group such as a primary amino group, a secondary amino group, a tertiary amino group, and a polymerizable vinyl group in one molecule, and For example, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, dimethylaminopropyl methacrylamide, dimethylaminopropylacrylamide, 2-vinylpyridine, 4
-vinylpyridine, dimethylallylamine, diallylmethylamine and the like. or,
Examples of their salts, ie, quaternized products, include hydrides, methylated products, ethylated products, and compounds in which the counter anion is a chlorine ion, bromide ion, hydroxyl ion, methyl sulfate group, etc. The molar ratio of the acidic vinyl monomer to the basic vinyl monomer is 45/55 to 55/45. If the blending ratio is outside the range of 45/55 to 55/45, the resulting crosslinked amphoteric copolymer will not have sufficient compatibility with water and will not have dispersion performance. The crosslinkable monomer according to the present invention is a compound having two or more functional groups capable of reacting with a vinyl group, an acid or a base in one molecule, such as methylenebisacrylamide, methylenebismethacrylamide, butane Diol diacrylate, butanediol dimethacrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, polypropylene glycol diacrylate, polypropylene glycol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate , allyl acrylate, allyl methacrylate, glycidyl acrylate, glycidyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, diacryloxyethyl phosphate, dimethacryloxyethyl phosphate, triallyl cyanurate, triallyl isocyanurate, Examples include divinylbenzene, diallyl maleate, polyallylsucrose, and the like. The amount of crosslinking monomer used is based on the total monomers.
It is 0.05 to 1 mol%. If you use too little,
The produced copolymer does not have a sufficiently satisfactory dispersing ability, and if the amount is too large, the produced copolymer does not dissolve or swell in water, making it unsuitable as a dispersant. The copolymerization reaction can be carried out by conventionally known methods, such as bulk polymerization, aqueous solution polymerization, reversed-phase suspension polymerization, and precipitation polymerization, at a reaction temperature of 20 to
The polymerization is smoothly carried out at 120°C, preferably from 35 to 80°C, in the presence of a radical polymerization initiator. As a radical polymerization initiator, sodium persulfate, potassium persulfate, ammonium persulfate, benzoyl peroxide, hydrogen peroxide, sodium peracetate,
Cumene hydroperacid, azobisisobutylnitrile, etc. are used. The amount of the radical polymerization initiator to be used varies depending on its type, but is generally preferably about 0.01 to 5% by weight based on the total monomers. In carrying out the present invention, in addition to the acidic vinyl monomer and the basic vinyl monomer, any other vinyl monomer copolymerizable with the acidic vinyl monomer and the basic vinyl monomer may be used. Although it can be copolymerized as a third component, it is necessary to suppress it to 60 mol% or less based on the total monomers. These vinyl monomers are monovinyl compounds that can be polymerized with a radical polymerization initiator, and include, for example, acrylic esters such as methyl acrylate and ethyl acrylate; methacrylic esters such as methyl methacrylate and ethyl methacrylate; Examples include styrene, styrene compounds such as a-methylstyrene, acrylamide, methacrylamide, vinyl ether, and vinyl acetate. The dispersant made of the crosslinked amphoteric copolymer of the present invention is
The viscosity of its 2% by weight solution (1 molar saline) (25
°C) is in the range of 500 to 10,000 centipoise, and stabilizes water-insoluble solid particles such as pigments, emulsifiers, water-insoluble bactericides, pearling agents, and abrasives, regardless of system pH and the presence or absence of soluble salts. It has the ability to be dispersed. In particular, those having the above-mentioned viscosity of 1000 centipoise or more are excellent dispersants. Such excellent effects have not been seen in conventionally known dispersants, and we aim to produce polymeric substances that exhibit high dispersion effects at any pH and in the presence of any soluble salts. This invention was made possible for the first time. EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to these Examples. Example 1 A glass ampoule with a capacity of 100 ml was replaced with nitrogen, and 15
℃ or below, add 50 g of water and acrylic acid to this ampoule.
7.2 g (0.1 mol), dimethylaminoethyl methacrylate 15.7 g (0.1 mol), methylenebisacrylamide 0.03 g (0.2 mmol), and potassium persulfate 0.03 g were placed in the tube and the tube was sealed. The sealed ampoule is immersed in a constant temperature bath at 70°C, and polymerization is carried out for 7 hours with occasional shaking. The entire polymerization system becomes a gel, which is poured into ethanol (1), stirred with a homomixer, pulverized, filtered and dried to obtain 22 g of crosslinked amphoteric copolymer in the form of a white powder (yield: 96%). The obtained crosslinked amphoteric copolymer was dissolved in 1M saline to make a 2% by weight solution, and the solution was measured using a B-type viscometer (1r.pm, 25% by weight).
The viscosity was measured using The viscosity was 3200 centipoise. The viscosities in the following Examples and Comparative Examples are all values determined by the above method. Comparative Example 1 The same operation as in Example 1 was performed except that methylenebisacrylamide, which is a crosslinkable monomer, was not used. White powder amphoteric copolymer (non-crosslinked) 22g (96
%) was obtained. The viscosity of the 2% by weight solution (1M saline) was 60 centipoise. Example 2 2-acrylamide as acidic vinyl monomer
The same operation as in Example 1 was carried out except that 20.7 g (0.1 mol) of 2-methylpropanesulfonic acid and 18.5 g (0.1 mol) of diethylaminoethyl methacrylate were used as the basic vinyl monomer, and 37 g (yield) of the crosslinked copolymer was obtained. 95%). The viscosity was 2300 centipoise. Comparative Example 2 The same operation as Example 2 was carried out except that the crosslinking monomer methylenebisacrylamide was not used.
37 g (yield 95%) of an amphoteric copolymer was obtained. The viscosity was 50 centipoise. Example 3 Styrene sulfonic acid as acidic vinyl monomer
18.4g (0.1mol), 4 as basic vinyl monomer
- The same operation as in Example 1 was carried out using 10.5 g (0.1 mol) of vinylpyridine and 0.04 g (0.2 mmol) of ethylene glycol dimethacrylate as the crosslinkable monomer, resulting in 27.7 g of crosslinked amphoteric copolymer (yield: 96%).
%) was obtained. The viscosity was 1300 centipoise. Comparative Example 3 The same operation as in Example 3 was carried out except that the crosslinkable monomer ethylene glycol dimethacrylate was not used to obtain 27.7 g (yield 96%) of an amphoteric copolymer.
The viscosity was 40 centipoise. Example 4 500 g of benzene,
58 g (0.8 mol) of acrylic acid, 136 g (0.8 mol) of dimethylaminopropyl methacrylamide, 1 g (4 mmol) of triallylisocyanurate, and 1 g of azobisisobutyronitrile were charged, and stirred at 80°C under a nitrogen stream for 8 hours. continued. In the initially homogeneous reaction system, as the polymerization progresses, the resulting copolymer begins to precipitate. After the reaction is complete, the precipitate is filtered and dried to form a powdery crosslinked amphoteric copolymer.
180g (yield 92%) was obtained. The viscosity was 2200 centipoise. Comparative Example 4 178 g (yield: 92%) of an amphoteric copolymer was obtained by carrying out the same operation as in Example 4 except that the crosslinking monomer triallyl isocyanurate was not used. The viscosity was 45 centipoise. Example 5 Methylsulfonic acid as acidic vinyl monomer
109 g (0.8 mol), 136 g dimethylaminopropyl methacrylamide as basic vinyl monomer
(0.8 mol) and 1.35 g (4 mmol) of trimethylolpropane trimethacrylate as the crosslinkable monomer were carried out in the same manner as in Example 4 to obtain 229 g (yield 93%) of a crosslinked amphoteric copolymer. . The viscosity was 1600 centipoise. Comparative Example 5 229 g (yield: 93%) of an amphoteric copolymer was obtained by carrying out the same operation as in Example 5, except that the crosslinkable monomer trimethylolpropane trimethacrylate was not used. The viscosity was 40 centipoise. Test Example 1 Using the crosslinked and non-crosslinked amphoteric copolymers synthesized in Examples 1 to 5 and Comparative Examples 1 to 5, the dispersion stability was investigated for the formulations (wt%) shown in Table 1. The results are shown in Table 1. (Test method and evaluation) Each composition was placed in a glass sample bottle and heated to 50°C.
The dispersion stability of the vinyl acetate particles was observed with the naked eye after storage in a constant temperature bath for one month. 〇: Uniformly dispersed ×: Vinyl acetate particles precipitate

【table】

【table】

[Table] Test Example 2 Using the crosslinked and non-crosslinked amphoteric copolymers synthesized in Examples 1 to 5 and Comparative Examples 1 to 5, the dispersion stability was investigated for the compounding compositions (% by weight) shown in Table 2. The results are shown in Table 2. (Test method and evaluation) Each composition was placed in a glass sample bottle and heated to 50°C.
The dispersion stability of the silica powder was observed with the naked eye. 〇: Uniformly dispersed ×: Silica powder is precipitated, and the upper part is almost transparent.

Claims (1)

[Claims] 1 acidic vinyl monomer or its salt 45-55 mol%,
A monomer mixture consisting of 45 to 55 mol % of a basic vinyl monomer or its salt and 0.05 to 1 mol % of a crosslinkable monomer is co-coated in the temperature range of 20 to 120°C in the presence of a radical polymerization initiator. Obtained by polymerization, the viscosity (25℃) of a 2% by weight solution (1 mol saline) is 500 ~
A dispersant consisting of a crosslinked amphoteric copolymer in the range of 10,000 centipoise.