JPH0135864B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermosetting aqueous emulsion in which a blocked isocyanate, a polyol and an amine-modified epoxy resin are mixed and dispersed in water. More specifically, the present invention provides blocked isocyanate (i),
Polyether polyol and/or polyester polyol having two or more hydroxyl groups in one molecule
The present invention relates to a polyurethane emulsion particularly suitable for paints, which is obtained by blending (ii) and a reaction product (iii) of an epoxy resin and an amino compound and then emulsifying the mixture. Solutions of compositions consisting of blocked isocyanates and polyols have been used in coatings as one-component compositions with a long pot life. In recent years, in consideration of pollution and various health and safety problems caused by the solvents contained in solvent-based paints, there has been an active shift to emulsion-type resins that use water as a medium. Polyurethane resin paints are no exception, and various efforts have been made to turn them into emulsions. However, polyurethane resins generally have a large cohesive force due to their urethane bonds and are difficult to disperse in water, making it difficult to obtain emulsions with good stability. Conventionally, in order to obtain a urethane resin emulsion with good stability, tertiary amino groups were introduced into the urethane resin and cationized with an acid aqueous solution to make it hydrophilic.After introducing a carboxyl group into polyurethane, an amino compound was A method of making it hydrophilic by using a salt such as an alkali, a method of introducing a polyoxyethylene chain into the molecule to obtain a self-emulsifying resin to make it hydrophilic, and emulsifying it in water. Methods such as adding and emulsifying are being implemented. It is difficult to improve performance because a large amount of hydrophilic parts remain in the coating films obtained from emulsions made by these methods.
Furthermore, when the coating film is immersed in water, the water penetrates into the coating film, resulting in disadvantages such as whitening, swelling, softening, and peeling of the coating film from the object to be coated. As a result of intensive research in order to improve the above-mentioned drawbacks, the present inventors have found that a compound produced by reacting an epoxy resin with an amine is mixed with a blocked isocyanate, a polyether polyol and/or a polyester polyol, and the mixture is emulsified. An aqueous polyurethane emulsion with unprecedented performance could be obtained, leading to the present invention. That is, the present invention is directed to blocked isocyanates (i) having two or more blocked isocyanate groups in one molecule, two or more hydroxyl groups in one molecule, and preferably two or more urethane bonds in some or all of the molecules.
(iii) a product of active hydrogen-containing reaction between a polyether polyol and/or polyester polyol (ii) and an epoxy resin and an amino compound having at least one of the above (i), (ii) and (iii). (ii) and (iii)
Active hydrogen in (i)/blocked isocyanate group in (i) = 0.5 to 1.5 (equivalent) and dispersed in water to provide a thermosetting aqueous emulsion. The present invention improves the adhesion of the coating film to the substrate by containing a reaction product of an epoxy resin and an amino compound in the composition, that is, when the coating film is immersed in water for a long time, Peeling from the base material can be prevented. Furthermore, in the present invention, the tertiary amino nitrogen that can be produced by the reaction between the epoxy resin and the amino compound acts as a catalyst that promotes the reaction between the isocyanate group and the hydroxyl group, thereby lowering the baking temperature of the coating film and reducing the baking temperature. It can shorten the time. After applying and drying the emulsion of the present invention, the cured coating becomes a completely transparent and colorless film.
It does not whiten or dissolve even when immersed in cold water, hot water, or hot alkaline water. The emulsion of the present invention is also useful as a paint that can be applied to metals, glass, ceramics, etc. and baked by heating (130°C to 200°C).
Therefore, the composition of the present invention improves coating film toughness, water resistance,
Taking advantage of its excellent alkali resistance and adhesion to glass, it is particularly useful as a coating agent for preventing glass bottles from scattering when they are broken, and is used after repeated washing with hot alkaline water. When the emulsion of the present invention is used as a paint, it may be colored with pigments or dyes, or a silane coupling agent may be added to further improve the adhesion of the paint film. It is also possible to add additives used in the paint field, such as antifoaming agents. Blocked isocyanate (i) used in the present invention
(a) Toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, hydrogenated 4,4'-diphenylmethane diisocyanate, tolidine diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, lysine diisocyanate, hexa Organic diisocyanates usually used as polyurethane raw materials such as methylene diisocyanate (b) The above organic diisocyanates, ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,4-butanediol,
1,6-hexanediol, glycerin, trimethylolpropane, pentaerythritol,
A compound having a terminal isocyanate group as a reaction product with a low molecular weight polyol such as triethanolamine (c) The organic diisocyanate of item (a) above, ethylene glycol, propylene glycol, glycerin, trimethylolpropane, pentaerythritol, sorbitol glucose, A polymer obtained by adding an alkylene oxide such as propylene oxide, butylene oxide, tetrahydrofuran, or a mixture thereof to a low-molecular active hydrogen compound such as ethylenediamine or bisphenol A as a starting material, and is a copolymer or a graft polymer. Reactants with polyether polyols, including compounds with terminal isocyanate groups, can be used to convert terminal isocyanate groups into phenol, ε-caprolactam, methanol, ethanol, 2-ethylhexanol, acetoxime, methyl ethyl ketoxime, cyclohexanone oxime, ethyl acetoacetate. , compounds blocked with monofunctional blocking agents for isocyanates commonly used in polyurethane chemistry such as diethyl malonate, and mixtures thereof. In addition, two hydroxyl groups are included in one molecule used in the present invention.
Polyether polyols and/or polyester polyols (ii) having at least 100% of the total number of polyethers include (a) active hydrogen compounds such as ethylene glycol, propylene glycol, trimethylolpropane pentaerythritol, glucose, sorbitol, glycerin, ethylenediamine, and bisphenol A as starting materials; Polymers obtained by adding propylene oxide, butylene oxide, tetrahydrofuran, etc. and mixtures thereof, polyether polyols including copolymers and graft copolymers, polyε-caprolactone polyols or polybasic acids, and mixtures thereof. Polyester polyols having terminal hydroxyl groups produced from alcohols, and optionally added to the polyether polyols and polyester polyols.
A mixture of polyoxyethylene polyol within a range of 10% by weight (b) The polyether polyol and/or polyester polyol of (a) above, if necessary,
A mixture of polyoxyethylene polyol within a range of 10% by weight, toluene diisocyanate, 4,4-diphenylmethane diisocyanate, hydrogenated 4,4-diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, hydrogenated Organic diisocyanates such as xylylene diisocyanate, isophorone diisocyanate, lysine diisocyanate, and hexamethylene diisocyanate, or terminal isocyanates obtained from these organic diisocyanates and low molecular weight active hydrogen compounds such as diethylene glycol, dipropylene glycol, trimethylolpropane, and pentaerythritol. Examples include polyurethane polyols having two or more hydroxyl groups in one molecule, which are obtained by reacting group-containing compounds.
Note that polyurethane polyol is preferred from the viewpoint of physical properties of the coating film after curing. When using a polyurethane polyol, the reaction between the polyol and the organic diisocyanate may be carried out before mixing with the blocking isocyanate and the epoxy resin.
It may be carried out at a relatively low temperature of 100°C. Furthermore, the epoxy resin used in the active hydrogen-containing compound (iii) obtained by reacting an epoxy resin and an amino compound, which is an important component in the present invention, is 2,2-bis(2,2-bis( 4-hydroxyphenyl)propane, bis(4
Diglycidyl ethers of bisphenols such as -hydroxyphenyl)methane, bis(4-hydroxyphenylethane), and bis(4-hydroxyphenyl)butane; polyglycidyl ethers of polyhydric phenols such as catechol and pyrogallol;
Further examples include diglycidyl ether of aliphatic or alicyclic OH group-containing compounds such as neopentyl glycol, polypropylene glycol, and hydrogenated bisphenol A; Glycidyl ether is used.
In addition, phenyl glycidyl ether, if necessary.
Monoepoxy compounds such as allyl glycidyl ether and butyl glycidyl ether can also be used in combination. The amino compound reacted with the epoxy resin used in the present invention is a primary or secondary monoamine, preferably a secondary monoamine. Examples of such amino compounds include methylamine,
ethylamine, propylamine, butylamine,
Dimethylamine, diethylamine, dipropylamine, dibutylamine, monoethanolamine,
Examples include diethanolamine and N-methylethanolamine. The reaction between the epoxy resin and the amino compound may be carried out in the absence of blocked isocyanate and/or urethane polyol, but it can also be carried out in their presence. Further, the amount of the amino compound that reacts with the epoxy resin may be an amount sufficient to open the epoxy ring of the epoxy resin or less than that. As the surfactant, common nonionic surfactants such as polyoxyethylene alkyl allyl ether, polyoxyethylene alkyl ether,
A block copolymer of propylene oxide and ethylene oxide, a compound obtained by adding polyethylene glycol to an isocyanate-terminated prepolymer obtained from polypropylene glycol and an organic diisocyanate, and the like are used. Further, anionic surfactants and cationic surfactants may be used in combination with these, but nonionic surfactants alone are particularly preferred. When carrying out emulsification, the surfactant may be added either to the mixture of blocked isocyanate and polyol (hereinafter referred to as the resin phase) or to the aqueous phase. The aqueous emulsion of the present invention is usually produced by dropping the resin phase into an aqueous phase stirred at high speed, by stirring the resin phase and aqueous phase together at high speed, or by adding water or hot water while stirring the resin phase. Add little by little
This is carried out by a so-called phase inversion emulsification method.
During such production, a solvent may be used for reasons such as adjusting the viscosity during the reaction, and if necessary, the solvent may be distilled off by heating under reduced pressure after emulsification. The aqueous emulsion of the present invention comprises the above-mentioned blocked isocyanate (i), polyether polyol and/or
or a polyester polyol (ii) and an active aqueous containing compound (iii) of an epoxy resin and an amino compound.
The active hydrogen in (ii) and (iii) / blocked isocyanate group in (i) = 0.5 to 1.5 equivalents, and if the equivalent ratio of active hydrogen / isocyanate group is out of range. This is not preferable because it reduces the reactivity of each component, and the active hydrogen/isocyanate group is preferably blended in an amount of 0.8 to 1.2 equivalents. The resulting aqueous emulsion of the present invention is suitable, for example, as a paint for preventing soft drink bottles from breaking, a chipping-resistant paint for automobiles, a soundproofing or vibration-proofing paint, and can also be used for other purposes. Next, the present invention will be described in detail with reference to Examples. Synthesis example (synthesis of blocked isocyanate A) a Takenate D-140-N 533g b Ethyl acetate 44g c Methyl ethyl ketone oxime 133g (Note) 75% solution of isophorone polyisocyanate in ethyl acetate, manufactured by Takeda Pharmaceutical Co., Ltd. Thermometer, stirring A and b were charged into a four-necked flask equipped with a reflux condenser, a reflux condenser, and a dropping funnel, and the air was replaced with dry nitrogen. Next, c was added dropwise from the dropping funnel over about 0.5 hours. The temperature rose due to heat generation, so it was cooled and kept at 70°C. After the dropwise addition was completed, stirring was continued for 30 minutes and the solution was taken out. The product is designated as blocked isocyanate A. Example 1 a Hyprox TG-3000 210g b Dipropylene glycol 18.8g c Xylylene diisocyanate 39.4g d Methyl ethyl ketone 96.4g e Dibutyltin diacetate 0.2g f Epicron 850 13.7g g Diethanolamine 7.4g h Blocked isocyanate A 2 32g i Pluronik F- 108 27.9g (Note) Manufactured by Dainippon Ink & Chemicals Co., Ltd., a triol with a molecular weight of 3000, which is made by adding propylene oxide to glycerin. Manufactured by Dainippon Ink & Chemicals Co., Ltd., epoxy value 189
Bisphenol A type epoxy resin manufactured by Asahi Denka Kogyo Co., Ltd., polypropylene glycol-polyethylene glycol block polymer A, b, c, d, and e were added to a four-necked flask equipped with a thermometer, stirrer, and reflux condenser. The mixture was heated at 70°C for 3 hours. Next, f was charged, and after uniformly dissolving, g was added. Furthermore, h and i were added and thoroughly stirred. Add 100g of warm water at 70°C to 100g of the resulting resin solution.
was added and stirred at high speed with a homomixer to obtain an emulsion. Example 2 a Hyprox TG-1000 200.0g b Isophorone diisocyanate 22.2g c Methyl ethyl ketone 92.3g d Dibutyltin diacetate 0.022g e Epicron 1050 47.5g f Diethylamine 7.3g g Blocked isocyanate A 251.5g h Pluronik F-68 31.4g (Note ) Manufactured by Dainippon Ink & Chemicals Co., Ltd., a triol with a molecular weight of 1000 made by adding propylene oxide to glycerin. Manufactured by Dainippon Ink & Chemicals Co., Ltd., epoxy value
475 bisphenol A type epoxy resin manufactured by Asahi Denka Kogyo Co., Ltd., polypropylene glycol-polyethylene glycol block polymer A, b, c, and d were charged into the same apparatus as in Example 2, and reacted at 70°C for 3 hours. Next, e was added and after completely dissolving, f was added. Furthermore, g and h were added and thoroughly stirred. 100 g of hot water at 70°C was added to 100 g of the obtained resin, and the mixture was stirred at high speed with a homomixer while maintaining the temperature at 70°C to obtain an emulsion. Comparative example 1 a Hyprox TG-3000 210g b Dipropylene glycol 18.8g c Xylylene diisocyanate 39.4g d Methyl ethyl ketone 89.4g e Dibutyltin diacetate 0.2g f Blocked isocyanate A 132.5g g Pluronic F-108 23.9g Same as Example 1 A, b, c, d, and e were charged into the apparatus and heated at 70°C for 3 hours. Next, f and g were added, stirred well, and taken out. Resin obtained 100
100 g of 70°C warm water was added to the mixture and stirred at high speed with a homomixer to obtain a good emulsion. Table 1 shows the physical properties of the coating films obtained from the emulsion of each Example and Comparative Example. The test method is JIS K
-5400. 【table】

Claims (1)

[Claims] 1. Blocked isocyanate (i) having two or more blocked isocyanate groups in one molecule, polyether polyol and/or polyester polyol (ii) having two or more hydroxyl groups in one molecule.
and an active hydrogen-containing compound (iii) obtained by reacting an epoxy resin and an amino compound,
(i), (ii) and (iii) are active hydrogen in (ii) and (iii) / (i)
Blocked isocyanate group in = 0.5-1.5 (equivalent)
A thermosetting aqueous emulsion that is formulated and dispersed in water. 2 Claims characterized in that the polyether polyol and/or polyester polyol (ii) having two or more hydroxyl groups in one molecule has two or more urethane bonds in some or all of its molecules. Thermosetting aqueous emulsion according to item 1.