JPS6330568A - Underwater curing amine-modified epoxy paint composition - Google Patents

Abstract

PURPOSE:To provide the title compsn. having excellent adhesion and corrosion resistance and suitable for use in coating underwater structures or the surfaces of structures in contact with water in the tide, such as marine structures, containing an amine-modified epoxy resin and a polyamide resin or a polyamine resin. CONSTITUTION:An epoxy resin (i) having at least one glycidyl ether group of the formula (wherein Z is H, CH3 or C2H5) (e.g., bisphenol A glycidyl ether) is reacted with an amine (ii) having at least one active hydrogen atom and pref. at least one hydroxyl group (e.g., ethanolamine) in an amount of 0.01-0.4 equivalents, pref. 0.05-0.2 equivalent of an active hydrogen atom per equivalent of epoxy group in the component (i) at room temp, or at 40-150 deg.C to obtain an amine-modified epoxy resin (a) having an epoxy equivalent of 1000 or lower, pref. 190-300. The component (a) is blended with a polyamide resin or a polyamine resin (b) as a curing agent and optionally, a pigment, an aggregate, a surfactant, a trixotropic agent, a silane coupling agent, etc., (c).

Description

Detailed Description of the Invention Technical Field The present invention relates to an underwater curable amine-modified epoxy coating composition, and more particularly, to coating surfaces that come into contact with water in underwater areas such as marine structures and in tidal zones. The present invention relates to a coating composition whose main ingredient is an amine-modified epoxy resin that has excellent adhesion and corrosion resistance and is easy to modify.

Conventional technology Diglycidyl ether of bisphenol A, which has excellent corrosion resistance, has been used as the main ingredient of underwater curing paints, but because the resin itself has few hydrophilic groups, it has poor wettability in water and secondary adhesion of cured films. It is known to be combined with a polyamide curing agent, which has poor properties and is more hydrophilic than a polyamine curing agent. However, since polyamide resin is highly hydrophilic and easily dissolves in water, it is necessary to design the paint viscosity with pigments etc. to be high in order to prevent elution from the paint film in the uncured state. This was reducing work efficiency. In recent years, for the purpose of imparting hydrophilicity to epoxy resins,
Attempts have been made to modify epoxy resin with phosphoric acid and cure it with polyamines, etc., but since phosphoric acid is highly reactive, epoxy resin and phosphoric acid are synthesized in advance in a special container under controlled conditions. However, such a resin must be used,
Although the objective of improving adhesion to some extent could be achieved, difficulties in reaction were pointed out.

Problems to be Solved by the Invention The object of the present invention is to provide an underwater-curable modified epoxy resin that is extremely easy to manufacture, has excellent underwater painting workability and adhesion of a cured film, and has long-term corrosion resistance. To provide a coating composition based on the present invention.

Means for Solving the Problems The underwater curable amine-modified epoxy coating composition of the present invention is
This is a two-component coating composition mainly composed of an amine-modified epoxy resin and a polyamine, which is obtained by mixing and stirring an epoxy resin and an amine during coating production.

In this invention, by reacting a part of the epoxy resin with an amine, a polar group is introduced into the molecule without losing the excellent anticorrosion performance and hardening properties of the epoxy resin, which improves underwater coating workability. and the adhesion of the cured film is improved.

The amine-modified epoxy resin of the present invention can be produced from an amine and an epoxy resin, and usually these are both mixed in such a manner that the active hydrogen equivalent of the amine is 0.01 to 0.4 equivalent per equivalent of the epoxy group in the epoxy resin. Preferably 0.05
The reaction is carried out at a ratio of ~0.2 equivalents. If the active hydrogen equivalent of the amine is less than Q,01 equivalent, the coating workability and adhesion of the cured film tend to be poor, and if it exceeds 0.4 equivalent, the viscosity increases. This reaction is usually carried out at room temperature or at 40 to
The reaction is carried out by stirring at a reaction temperature of 0°C. Alternatively, an amine-modified epoxy resin obtained by reacting an amine and an epoxy resin in the above-mentioned mixing ratio may be used as the paint resin.

The epoxy equivalent of the amine-modified epoxy resin thus obtained is 1000 or less, preferably 190 to 30.
It is about 0.

The epoxy resin used as a raw material in this invention has at least one glycidyl ether group in the molecule represented by the following formula (in the formula, Z is -H1-CH, -C,H,). Representative examples include diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, phenol novolac epoxy resin, and diglycidyl ether of alkylene oxide adducts of bisphenols.

As the amine in this invention, any amine compound can be used as long as it has at least one active hydrogen, such as methylamine, dimethylamine, ethylamine, diethylamine, ethanolamine, aniline, xylene diamine, etc. In particular, amines having at least one hydroxyl group in the molecule and having two or more active hydrogens, such as ethanolamine, are preferred.

As the curing agent for the amine-modified epoxy resin in this invention, all the usual curing agents for epoxy resins can be used, such as aliphatic polyamines, aromatic polyamines, alicyclic polyamines, polyamide resins, and polymer captans. Among them, polyamine resins are preferred.

The amount of curing agent used is also the amount used as a normal curing agent, and is usually 0.5 to 1 equivalent of epoxy group, in the case of polyamine, the amine equivalent, and in the case of polymercaptan, the active hydrogen equivalent of the mercaptan. An amount of about 2.0 equivalents is sufficient.

Further, the underwater curable amine-modified epoxy coating composition according to the present invention may contain pigments and aggregates used in conventional underwater curable coatings as appropriate. The pigments and aggregates used have a high specific gravity and excellent corrosion resistance, in addition to their coloring function, to prevent the coating material from floating due to the difference in specific gravity with water when painting underwater. is preferred. Examples include titanium oxide, zinc oxide, iron oxide, aluminum oxide, aluminum powder, barium sulfate, calcium sulfate, calcium carbonate, magnesium carbonate, talc, clay, kaolin, mica, graphite, silica, diatomaceous earth, and asbestos. As aggregate,
Examples include silica sand, glass flakes, glass fibers, synthetic fibers, natural or artificial mica diath iron oxide, and the like. The blending amount of the pigment and aggregate is preferably 6% or less as the volume concentration of the pigment and aggregate in the entire composition.

Furthermore, if desired, a surfactant,
It is also possible to add modifiers such as thixotropic agents, silane coupling agents, and inhibitors, non-reactive diluents for viscosity adjustment, solvents, and the like.

The underwater curable amine-modified epoxy coating composition according to the present invention can be easily applied to steel materials, concrete, etc. underwater with a brush, roller, trowel, etc., and compared to conventional epoxy underwater curable coatings, It has the following advantages:

■It is possible to save labor in the process of synthesizing paint resin.

■Good wettability to the surface to be coated and excellent painting workability.

■Excellent adhesion of cured film.

■It is an electrically high resistance film and has excellent corrosion resistance.

As mentioned above, the underwater-curable amine-modified epoxy coating composition of the present invention can shorten the manufacturing process, has excellent underwater painting workability, and the formed coating film has a large corrosion-preventing effect over a long period of time. Suitable as a coating material.

EXAMPLES Below, the present invention will be explained in more detail by showing Examples and Comparative Examples. In Examples and Comparative Examples, all parts are by weight.

In addition, the evaluation method in Examples and Comparative Examples is as follows.

Underwater painting workability: O indicates that 100% of the coated surface can be covered with one stroke with a spatula, ○ indicates that 100% of the coated surface can be covered with two strokes with a spatula, and 3 or more coats with a spatula × means that 100% of the surface to be coated can be covered by rubbing.

Wettability to the surface to be coated: Visually observe the contact angle of the cured film applied with a spatula to the surface to be coated.
Less than Δ, 90” or more ×.

Adhesion: 95% or more of remaining coating area by cross-cut test at 10-part intervals 0194-80% 0.79-50% Δ, 4
9% or less

Electrical resistance of paint film: AC resistance value of paint film.

Measurement conditions (electrode area: 50cj, frequency: 1kHz). Measuring device (CJA-3 type food coating tester: manufactured by Shindenshi Kogyo) Example 1 100 parts of bisphenol A diglycidyl ether (epoxy equivalent: 190) and 2 parts of ethylamine were mixed at room temperature with a stirrer, and 10 parts of titanium oxide was mixed. 1 part, 50 parts of talc, and 30 parts of glass flakes were further mixed to form a main ingredient. The base resin was prepared and aged for 24 hours, and 50 parts of a modified aliphatic polyamine (Fujicure $5405, Fuji Kasei) as a curing agent was mixed with the non-reactive diluent Hysol 5AS296 (Nippon Petrochemical) as a viscosity modifier. An appropriate amount of the paint was added to form a water-curable amine-modified epoxy paint composition.

Underwater coating workability when coating a steel plate with a spatula to a thickness of about 3' plate in seawater during the pot life using this composition,
The wettability to steel surfaces was evaluated.

Furthermore, after one month of immersion, the adhesiveness and electrical resistance of the cured film were measured.

The above results are shown in Table 1. However, the steel plate used was a 3,2-thick steel plate that had been rusted in seawater for one year and treated with a wire brush to 5t-3 (according to SIS, 05-5900).

Example 2 100 parts of bisphenol A diglycidyl ether (epoxy equivalent: 190) and 2 parts of ethylamine were mixed, and 80 parts of ethylamine were mixed.
The reaction was carried out at °C for 3 hours to obtain an amine-modified epoxy resin. Using this resin, all other treatments were carried out in the same manner as in Example 1.

Example 3 The same procedure as in Example 1 was carried out except that ethanolamine was used in place of ethylamine as the amine for modifying the epoxy resin in Example 1.

Example 4 In place of the modified aliphatic polyamine as the curing agent in Example 1, a modified aromatic polyamine (Sanmide M-180
0.0, Sanwa Kagaku), and all other treatments were carried out in the same manner as in Example 1.

Example 5 Bisphenol F diglycidyl ether (epoxy equivalent: 190) was used in place of bisphenol A diglycidyl ether in Example 1, and all other treatments were carried out in the same manner as in Example 1.

Example 6 0.5% by weight of an alkyl phosphate (Electrostripper N, Kao Atlas) was added to the composition of Example 4, and the composition was treated in the same manner as in Example 1.

Comparative Example I A paint was manufactured according to the formulation of MIL-P-28579 (YD), and the same evaluation as in the example was performed using the paint. The results are shown in Table 1.

Comparative Example 2 100 parts of bisphenol A diglycidyl ether (epoxy equivalent: 190) was mixed with the same pigment formulation as in Example 1 in the same proportion, and modified aliphatic polyamine (Fujicure #540)
5, Fuji Kasei) were mixed to obtain a comparative composition. Using this composition, evaluations similar to those in Examples were performed, and the results are shown in Table 1.

(Margin below) Table 1 Handbook continuation supplementary book August 26, 1986

Claims (2)

[Claims] (1) An underwater curable amine-modified epoxy coating composition comprising an amine-modified epoxy resin obtained by reacting an epoxy resin with an amine, and a polyamide resin or a polyamine resin as resin components. (2) The composition according to claim 1, wherein the amine has at least one hydroxyl group in the molecule.