JPS597834B2 - Method for producing aqueous resin coating composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an aqueous resin coating composition.

In recent years, the demand for polymer compounds has increased in terms of paints, but since these often use organic solvents, there is always a risk of fire, and furthermore, they can cause air pollution, solvent poisoning, skin disorders, etc. It has become a major social problem and has caused such harm.

Generally, one method for solving the above-mentioned problems is to use water instead of an organic solvent.

However, when water is simply used instead of an organic solvent, the physical properties are often inferior to organic solvent type resin compositions, and the same is true for urethane resins. The film obtained from water-dispersible urethane resin has tensile strength,
The tear strength, elongation rate, water resistance, etc. are inferior to those of urethane resins obtained from organic solvents, so when used as a base material or surface treatment agent when manufacturing synthetic resin leather, for example, It was not possible to obtain a product that was fully satisfied with the physical properties described above. In order to eliminate these drawbacks, attempts have been made to improve the urethane resin itself or to consider water dispersion methods, but it has been extremely difficult and no satisfactory product has yet been obtained. be.
The present invention provides a solvent-free resin coating composition that eliminates these disadvantages and has excellent physical properties and workability that are comparable to conventional resin compositions containing solvents. It is something.

That is, the present invention is characterized in that a composition consisting of 86 to 97% by weight of an emulsion mainly composed of urethane resin and 14 to 3% by weight of a self-emulsifying epoxy resin emulsion is spread on a fibrous base material and heat-treated. This is a method for producing an aqueous resin coating composition.

A resin coating composition made of such a mixture has excellent water resistance, tensile resistance, resistance to discoloration due to weathering, resistance to weathering deterioration, etc., and also has an increased softening temperature, excellent non-tackiness, and particularly excellent elongation. Then, the coating composition obtained by spreading this composition onto a fibrous base material by an appropriate method and heat-treating it can be crosslinked at extremely low temperatures and has a good texture. Although the reasons for these improvements in physical properties are still unclear and require further research, it is important to note that the oxirane ring in the epoxy resin is the -NH group, -COOH group, -OH group, NHCOO group, and NHCONH group in the urethane resin. It is thought that a crosslinked structure is formed by reacting with The mixing ratio of the above-mentioned urethane resin and epoxy resin of the present invention is urethane resin 86-97% and epoxy resin 14-3% by resin weight.
Within this range, any ratio can be taken depending on the purpose.

If the proportion of the epoxy resin is less than 3%, a sufficient crosslinked structure will not be formed and the softening point may be lowered or the composition may become sticky, which is not very preferable. On the other hand, if it exceeds 14%, the resulting product will become soft and the texture will be impaired, so it is best to keep it within the above range. It is preferable to mix these emulsions while stirring them using a conventional stirrer. For example, this can be easily achieved by gradually adding and mixing the epoxy resin emulsion while stirring the urethane resin emulsion using a disper stirrer. In addition, the fibrous base material in the present invention refers to a base material such as a woven fabric, knitted fabric, or non-woven fabric made of natural fibers such as cotton, silk, and wool, or chemical fibers such as polyamide, polyester, polyacrylonitrile, polyvinylidene chloride, and rayon. The method of spreading onto these base materials is a direct method such as dipping, spraying, doctor knife method, gravure method, or brush coating method, or a mold release material is coated with the above coating method and the Dojo fiber base material is pasted. An indirect method, in which the film is applied and then peeled off, can be used. Further, the coating thickness may be applied to an arbitrary thickness depending on the purpose of use of the obtained product. The fibrous base material spread in this way progresses to crosslinking at about 100 to 150°C, making it possible to crosslink at so-called low temperatures.
A coating composition having a good texture and a strong resin film can be obtained by heat treatment for a few minutes. The urethane resin used in the present invention may be any resin as long as it can be made into an emulsion type.

For example, using a conventionally known method, ie, a polymeric polyol having active hydrogen groups at both ends, such as polyester or polyether, is reacted with a diisocyanate, and the resulting urethane polymer having terminal isocyanate groups is prepared. Dilute with dimethylformamide, methyl ethyl ketone, tetrahydrofuran, etc., and react with a chain extender having a hydrophilic group, and use a small amount of polyol as a reaction terminator, such as ethylene glycol, propylene glycol, or a compound having a hydrophilic group and an active hydrogen group. For example, it is obtained by adding N-methyldiethanolamine, N,N-dioxypropylnaphthyramine, etc., and is made into a water-dispersible solution. Of course, it is also possible to use commercially available urethane resin emulsions prepared by methods other than those described above. Examples of the isocyanate compound used in the production of the urethane resin include resin group diisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, 2,6-lysine diisocyanate, 4,4''-diphenylmethane diisocyanate, 2.
Aromatic diisocyanates such as 4' and 2,6-tolylene diisocyanate, m-xylylene diisocyanate, and the like.

Furthermore, examples of the polymer polyol include polyether, polyester, and polyester/polyether having hydroxyl groups, and examples of polyethers that can be used include polyethylene glycol and polypropylene glycol.

Polyesters include polyhydric alcohols such as ethylene glycol, propylene glycol, 1,6-hexanediol, trimethyltyrrolpropane, zorbitan, etc. and polyhydric carboxylic acids such as succinic acid, adipic acid,
fumaric acid, glutaric acid, terephthalic acid, isophthalic acid,
Examples include condensates of biromellitic acid, condensates of hydroxycarboxylic acids and polyhydric alcohols, and lactone polymers. As the polyester/polyether, there may be used polyesters obtained by addition polymerizing alkylene oxide to the above-mentioned polyesters, polyesters/polyniethers having hydroxyl groups at the terminals obtained by condensing polyethers and polycarboxylic acids, and the like. As a chain extender, ethylene glycol,
Propylene glycol, 1,4-butanediol, 1.
Diols such as 6-hexanediol and diethylene glycol, aliphatic diamines such as ethylenediamine, hexamethylenediamine, and trimethylhexamethylenediamine, and alicyclic diamines such as isoboronediamine, viperazine, aminoethylpiperazine, and 2,5-dimethylbiperazine. Diamines are used.

The present invention is mainly based on the above-mentioned polyurethane resin emulsion, but examples of other synthetic resin emulsions that may be mixed therein include polyvinyl chloride, acrylic, and the like. In addition, the self-emulsifying epoxy fat emulsion used in the present invention is a reaction product of epichlorohydrin and bisphenol A (bisphenol A
type).

Generally, epoxy resin emulsions produced using emulsifiers have excellent long-term storage stability, but when used as paints, those using emulsifiers may have poor film-forming properties and the resulting film may have poor water resistance. However, since the epoxy resin emulsion used in the present invention is of a self-emulsifying type, it imparts a viscosity with good workability when applied to a fibrous base material. A specific example of the epoxy resin is bisphenol A diglycidyl ether. Also, the epoxy equivalent is 150 to 10001
Preferably it is 195-210. Epoxy equivalent is 15
If it is less than 0, the film obtained will be brittle and have poor performance such as adhesion and chemical resistance, while if the epoxy equivalent is 10
If it exceeds 0.00, the viscosity tends to become high and the viscosity needs to be adjusted, which is not very preferable. The table below shows a comparison of the physical properties of conventionally commercially available aqueous resin films and the film of the present invention, and it is clear how superior the film made by adding the epoxy resin of the present invention is.

Next, the present invention will be described in detail with reference to Examples, but the effectiveness of the present invention is not limited thereto.

Furthermore, in the examples, parts simply refer to parts by weight. Example
1 Polyurethane resin emulsion (solid content 30%) 100
1 part, 4 parts of bisphenol A-based epoxy resin emulsion (solid content 60%, Epiclon EM-85, trade name manufactured by Dainippon Ink & Chemicals Co., Ltd.), and 8 parts of colorant (brown) were mixed with a Dispa stirrer (400 rpm). Mix with stirring to produce a mixed emulsion of polyurethane and epoxy resin.

Next, the mold release material is knife-coated with the above mixed emulsion to a thickness of 0.3, and the mixture is introduced into a hot air circulation heating furnace heated to about 150° C. for about 3 minutes to dry, thereby forming a film of the synthetic resin. Next, while reheating the film surface, the raised resin-treated surface of the cotton twill fabric base fabric, which has been previously brushed and coated with a heat-sensitive or pressure-sensitive adhesive, is laminated.
This was peeled from the mold release material while being cooled to obtain a resin coating composition. This coating exhibited extremely little decrease in elongation compared to a film made of polyurethane alone, and had extremely excellent film strength and water resistance even under relatively low heating conditions. Example 2 Polyurethane resin emulsion (solid content 30%) 100
1 part, 8 parts of bisphenol A-based epoxy resin emulsion (solid content 60%), and 7 parts of colorant (black) were stirred with a disper stirrer at 400 rpm to produce a mixed emulsion of polyurethane and epoxy resin.

This emulsion is defoamed using a defoaming machine, and Tetron/
Roll coating was performed on a cotton blend plain weave base fabric to a thickness of 1.571i11.

Subsequently, this coated material was introduced into a hot air circulation heating furnace at about 180° C. for about 3 minutes to undergo heat treatment. This was taken out from the furnace and cooled. This coating showed no decrease in elongation compared to conventional water-based resins, and had extremely excellent film strength and water resistance even under relatively low heating conditions. Example 3 Polyurethane resin emulsion (solid content 30%) 100
1 part, 8 parts of bisphenol-based epoxy resin emulsion (solid content 60%), and 7 parts of colorant (blue) were stirred using a disper stirrer at 400 rpm to prepare a mixed emulsion of polyurethane and epoxy resin.

Claims (1)

[Claims] 1 Emulsion 86 based on polyurethane resin
97% by weight and self-emulsifying epoxy resin emulsion 1
1. A method for producing an aqueous resin coating composition, which comprises spreading a composition comprising 4 to 3% by weight on a fibrous base material and heat-treating it.