JPS5874742A - Resin dispersion - Google Patents

Abstract

PURPOSE:To provide a resin dispersion capable of forming coating film excellent in adhesion and resistance to water and corrosion, by polymerizing a vinyl monomer in a water-sol. solvent containing polyalkylene glycol, and then adding water to the polymer. CONSTITUTION:In a water-sol. solvent (e.g., methanol, ethylene glycol monoethyl ether) is dissolved 2-25pts.wt. polyalkylene glycol, MW 600-20,000 (e.g., polyethylene glycol). Then, 100pts.wt. polymerizable vinyl monomer (e.g., methyl acrylate, styrene) is added to the soln., and the mixt. is polymerized at about 50-150 deg.C in the presence of a radical polymn. initiator. Next, water is added slowly with stirring to the resulting polymer resin soln. forming a resin dispersion.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to aqueous dispersions of vinyl polymers free of emulsifiers and protective colloids.

Water-based paints have attracted particular attention in recent years because they are low-pollution and resource-saving. However, water-based paints have the disadvantage that the drying properties, water resistance, corrosion resistance, and gloss of the coating film are poor, and there are many problems that must be solved.

Generally, water-based resins include water-soluble resins and water-dispersible resins.
Each has its own characteristics. For example, water-soluble resins produced by neutralizing carboxyl groups with ammonia or amines are comparable in workability to organic solvent-based resins, and have excellent gloss and corrosion resistance, but they contain 30-50% by weight of organic solvents in the paint. Because of this, problems remain in terms of pollution control. In addition, there is an odor due to ammonia or amine, and the drying properties and water resistance of the coating film are poor. Furthermore, as the molecular weight of the polymer increases, the viscosity increases, so there is also the drawback that products containing high molecular weight polymers cannot be used.

On the other hand, dispersions produced by emulsion polymerization in the presence of emulsifiers and protective colloids, or dispersions obtained by mechanical dispersion, have high fa and relatively low viscosity, regardless of molecular weight. Although it has features such as almost no use of organic solvents or amines, and excellent drying properties, the coating film has poor gloss and workability, and the water resistance and corrosion resistance of the coating film are affected by the emulsifiers and protective colloids used. , has disadvantages such as poor adhesion. Therefore, in recent years, various colloidal dispersible resins that take advantage of the advantages of both water-soluble resins and water-dispersible resins have been studied.

As a result of intensive studies to solve the problems in this background, the present inventors used film-protecting colloids and emulsifiers by introducing polyalkylene glycol into a polymerization reaction system in a water-soluble solvent. The present inventors have discovered that a resin dispersion can be obtained that is stably dispersed without any problems, and that the resulting coating film has excellent adhesion, water resistance, and corrosion resistance.

That is, in the present invention, 100 parts by weight of a polymerizable vinyl monomer is polymerized in a water-soluble solvent in which 2 to 25 parts by weight of polyalkylene glycol having a molecular weight of 600 to 20,000 is dissolved, and then water is added and dispersed. The present invention provides a resin dispersion obtained by

The resin dispersion of the present invention contains 2 to 25 parts by weight of polyalkylene glycol per 100 parts by weight of the vinyl copolymer component, so that it has self-dispersing ability and can be easily dispersed in water. By charging polyalkylene glycol into the reaction system in advance and then polymerizing the monomers, chemical bonding (grafting) to the vinyl copolymer and physical fusion of the polymer and polyalkylene glycol occur simultaneously in four steps to improve self-dispersion ability. This is important in order to obtain a polymer with

Examples of the polyalkylene glycol include one or more of polyethylene glycol, polypropylene glycol, pro- and wolfberry copolymers of polyethylene glycol and polypropylene glycol. Particularly preferred is polyethylene glycol. The amount to be used should be determined based on the combination of the dispersibility imparting effect of the resin and the water resistance, corrosion resistance, etc. of the coating film, but it is preferably 2 to 25 parts by weight based on ~100 parts by weight of the monomer. 5 to 15 parts by weight is optimal depending on various considerations. If the amount is less than 2 parts by weight, there will be almost no dispersion effect, and if it exceeds 25 parts by weight, the grafting efficiency will hardly increase and water resistance will deteriorate. Regarding the molecular weight of polyalkylene glycol, it is 60
If it is less than 0, the hydrophilicity will be poor and the dispersion effect will not improve;
If it exceeds D.000, grafting with the vinyl copolymer or fusion with the polymer may occur, and the dispersion effect will not be improved.

As for water-soluble solvents, it is desirable to select ones that have the ability to dissolve polymers and are effective in reducing the applicability of the paint after it is made (washing, sagging, drying properties, etc.). , cellosolve series such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol motsubutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monofloyl ether, diethylene glycol motsubutyl ether, etc. The carpitol family and their derivatives are the core. The amount used is 100 resin solids.
20 to 100 parts by weight is desirable. If it is less than 20 parts by weight, the viscosity of the solution will increase during the reaction, which will hinder the polymerization reaction, and if it exceeds 100 parts by weight, the viscosity of the resin dispersion will increase and the dispersion stability will decrease, and it will also go against resource conservation. do.

More preferably, the amount is such that the amount in the final resin dispersion is 30 or less.

Polymerization of the polymerizable vinyl monomer can be carried out by a conventional solution polymerization reaction method, and there are no particular limitations. At that time, the reaction source ItFi90℃
The above is preferable from the viewpoint of good grafting efficiency. Furthermore, any monomer suitable for use in coatings can be selected as long as it does not interfere with polymerization.

Examples of the polymerizable vinyl monomer that can be used in the present invention include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, crotonic acid, and itaconic acid, methyl acrylate, ethyl acrylate,
Acrylic acid esters such as isopropyl acrylate, isopropyl acrylate, n-butyl acrylate, tert-butyl acrylate, inbutyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, Inglovir methacrylate, n-butyl methacrylate, tert-butyl methacrylate, isobutyl methacrylate, methacrylic acid esters such as 2-ethylhexyl methacrylate, styrene monomers such as styrene, vinyltoluene, α-methylstyrene, vinyl acetate , β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate,
Glycidyl acrylate, glycidyl methacrylate, acrylamide, methacrylamide, N,N-dimethylacrylamide, N,N-diethylmethacrylamide, acrylonitrile, methacrylonitrile, ethylene, vinyl chloride, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, etc. Alternatively, a mixture of two or more is used.

Polymerization of the polymerizable vinyl monomer is preferably carried out at 50 to 150°C in the presence of a water-soluble solvent, polyalkylene glycol, and a radical polymerization initiator. As the radical polymerization initiator, azobisisobutyronitrile, azobisvaleronitrile, benzoyl peroxide, t-
Oil-soluble radical polymerization initiators such as ptyrno)hydronochloride oxide are useful.

One of the features of the present invention is that by selecting the type of monomer, it is possible to produce a resin dispersion that has anionic, nonionic, or cationic ionicity after water dispersion, and can be used alone or in combination in a wide variety of fields of application. This means that it will be possible to expand the

In addition, when dispersing the polymer resin solution in water, it is desirable to add the resin to the water and slowly add and disperse the resin while stirring.

Although the resin dispersion of the present invention can be used as it is,
It is also possible to add pigments, plasticizers, solvents, colorants, etc., or to blend a wide range of water-soluble or water-dispersible resins such as modified amino resins, epoxy resins, polyester resins, and acrylic resins.

The resin dispersion of the present invention can be directly kneaded with pigments, and does not suffer from the problems of dispersion stability and foaming that occur with emulsion polymers.

The paint obtained using the composition of the present invention can be applied to wood, paper, fiber, plastic, ceramic, inorganic materials, etc. by dipping, coating, spraying, roll coating, etc. It can be painted on the surfaces of cement base materials, iron, non-ferrous metals, etc.

Next, the present invention will be explained in detail with reference to examples.

Example 1 Ethyl cellosolve 30 was added to 21 flasks equipped with a stirrer, thermometer, rapid flow condenser, dropping funnel, and inert gas inlet.
0t.

Prepare polyethylene glycol #4000 70F,
The temperature is raised to 130C under a nitrogen gas stream. Separately, 476f of methyl methacrylate, 210t of butyl acrylate, and 14f of methacrylic acid were weighed and mixed in advance as vinyl monomers, and tertiary butyl acrylate was mixed in advance.
Oxide 14F was weighed and injected from separate dropping ports to uniformly dropwise polymerize over 3 hours. 1 more
Maintain at 30° C. for 2 hours to complete polymerization.

Next, the mixture was cooled to 80°C, and at the same temperature, 876 tons of water was added dropwise over 2 hours to achieve dispersion, and then cooled to 25°C.

The resin dispersion thus obtained has a non-volatile content of 40 cm, a viscosity of 1250 cps, a pH of 5.4, and an average particle diameter of α2μ or less.

Example 2 Using the same apparatus as in Example 1, add isopropyl glycol 300 f% polyethylene glycol*6o to a flask.
o.

100 tons were charged and the temperature was raised to 100C in a nitrogen gas stream.

Methyl methacrylate 441 as a separate vinyl monomer
9゜224f of 2-ethylhexyl methacrylate and 55t of dimethylamidiethyl methacrylate were weighed and mixed in advance, and at the same time tertiary-butylperoxy-2-
5 tons of ethylhexanoate was weighed out and injected from separate dropping ports, and the mixture was uniformly dropped and polymerized over a period of 3 hours. Further, the temperature was maintained at 100° C. for 2 hours to complete the polymerization.

Next, the mixture was cooled to 90°C, 907f of water was added dropwise at the same temperature over 2 hours to achieve dispersion, and the mixture was cooled to 25°C.

The resin dispersion thus obtained has a nonvolatile content of 40%, a viscosity of 110 cps, a pH of 6.1, and an average particle size of 0.2 μm or less.

Example 3 Using the same apparatus as in Example 1, diethylene glycol monoethyl ether 400f1 polyethylene glycol $2000 100r was charged into a fusco, and the temperature was raised to 130C in a nitrogen gas stream. Separately, styrene 465.5f is used as a vinyl monomer.

Butyl acrylate 2102, β-hydroxyethyl methacrylate 21t1, γ-methacryloxypropyltrimethoxysilane & 5r were weighed and mixed in advance, and at the same time, tert-butyl peroxydipenzoate 21f was weighed and injected from separate drip ports. Uniform dropwise polymerization takes place over a period of 3 hours.

Further, the temperature was maintained at 130° C. for 2 hours to complete the polymerization.

Next, it is cooled to 80°C, and at the same temperature, 831f of water is added dropwise over 2 hours to achieve dispersion, and then it is cooled to 25°C.

The resin dispersion thus obtained has a nonvolatile content of 40 cm, a viscosity of 60 cps, a pH of 4.5, and an average particle diameter of α2μ or less.

Comparative Example 1 Using the same apparatus as in Example 1, ethyl cellosolve 300
After charging f, the same amount of the vinyl monomer and catalyst used in Example 1 were added to complete the polymerization reaction at 130°C for 3 hours, and at the same temperature, polyethylene glycol $4000 was added after 70f and dissolved and mixed. When the temperature was lowered to 80°C and 876f of water was added dropwise over 2 hours to disperse the mixture in the same manner as in Example 1, the viscosity of the system increased significantly and a stable dispersion could not be obtained.

Comparative Example 2 Polymerization was carried out based on the composition of manure using a normal emulsion polymerization method,
Synthesis of acrylic copolymer emulsion.

Butyl acrylate 30 0 Methacrylic acid 2 Sodium dotecylbenzenesulfonate 4 Ammonium persulfate 0.3 Ion exchange water
156.4 total
2607 non-volatile content 40%, viscosity 2
00 cps, pH 3,5 Comparative Example 3 Polymerization is carried out according to the following composition using a conventional method, followed by neutralization and dilution with water to obtain an acrylic water-soluble resin.

Butyl acrylate 40 Methacrylic acid 10 Butyl selonup 70 Tertiary-butyl peroxydipenzoate 1 Triethylamine 12 Non-volatile content 40
%, viscosity 20,000 cpa, pH 9.2 Test Examples The resin dispersions obtained in Examples 1 to 3, the emulsion copolymers obtained in Comparative Example 2.3, and the water-soluble resins were made into paints). , and its coating film properties are shown in Table 1.

In addition, the mixed liquid obtained by adjusting the pH of the dispersions of Examples 1 and 2 to around 7 with a volatile alkali and acid, respectively, and then blending them at a solid content ratio of 1/1 remained stable, and the resulting clear - The film has better water resistance and alkali resistance than the clear films of Examples 1 and 2. This is thought to be due to ionic crosslinking.

Claims (1)

[Claims] 1 in a water-soluble solvent in which 2 to 25 parts by weight of polyalkylene glycol having a molecular weight of 600 to 20,000 are dissolved.
After polymerizing 00 parts by weight of a polymerizable vinyl monomer,
A resin dispersion obtained by adding and dispersing water.