JPH0474385B2 - - Google Patents

Description

[Detailed description of the invention]

Technical Field The present invention relates to a two-component epoxy coating composition,
More specifically, the present invention relates to a two-component epoxy coating composition that is made by combining a specific modified epoxy resin and a specific crosslinking agent and is useful for forming protective coatings for concrete deterioration prevention coatings, automobiles, marine structures, etc. Prior Art Paints containing epoxy resin as a vehicle form a strong coating film upon curing and have excellent chemical resistance, adhesion, weather resistance, heat resistance, etc., so they are expected to have a wide range of applications. On the other hand, drawbacks have been pointed out, such as short pot life, low deflection, and the need for solvents such as esters and ketones to dissolve polymers, resulting in a decline in coating performance. is recieving. Recently, the use of polymeric epoxy resins, which have excellent barrier properties against water, chlorine ions, carbon dioxide gas, etc., has been attracting attention for the purpose of preventing deterioration of concrete, etc., but the lack of elasticity is fatal in terms of crack followability. It has become flawed and has not seen success. In an attempt to impart elasticity to epoxy resins, a technology has been developed to blend amino group-terminated butadiene-acrylonitrile copolymer elastomers in the fields of compositions for lining water pipes, adhesives, etc. Japanese Patent Publication No. 57-34151; 58-49721;
59-4656; 59-84915; 57-30721; 59-59719, etc.) These are all application techniques for lining materials and adhesives, and it is impossible to immediately use them as paints. This is because the pot life of any of the technologies is short, making them unsuitable as paints, and the viscosity is too high, so if you add a solvent to adjust the viscosity, the film performance will deteriorate, making it extremely difficult to make into paints. Because there is. Furthermore, attempts have been made to add plasticizers to high-molecular epoxy resins or to modify the epoxy itself, but in the former case, the plasticizers may be eluted from the coating film, resulting in poor corrosion resistance, chemical resistance, etc. However, there is a problem with the compatibility of plasticizers and epoxy resins, and the latter may reduce adhesion, corrosion resistance, or water resistance, and the expected improvement in flexibility may not be achieved, especially from the viewpoint of crack followability of concrete. It is insufficient and has not been put into practical use. Therefore, urethane rubber paints with good elongation are generally used, but even if the problem of crack followability has been cleared, urethane paints are easily affected by moisture, are difficult to obtain a uniform film due to foaming, etc., and have problems with oxygen permeability. Problems with workability and coating film performance have been pointed out, such as high heat resistance and poor barrier properties, and the current situation is that a fully satisfactory concrete deterioration prevention coating has not been found. Problems that the invention aims to solve: Therefore, the paint is based on a relatively high molecular weight epoxy resin that has excellent coating film properties, especially its barrier properties against moisture, chlorine ions, carbon dioxide gas, etc., and is adjusted to an appropriate viscosity using a solvent. If we can obtain a composition that can provide a highly elastic coating film that does not deteriorate film properties even when used as a coating material, has a sufficient pot life for coating applications, and can follow cracks, it would be possible to obtain a composition that can be used to prevent deterioration of building materials such as concrete. It is useful as a paint for bad iron substrates, a chipping paint for automobiles, a material for marine structures, and many other purposes, and it is an object of the present invention to meet such demands. Means for Solving the Problems According to the present invention, the above-mentioned objects of the invention are: (a) a dimer acid-modified epoxy resin and/or a nitrile rubber-modified epoxy resin having a molecular weight of 2,000 to 10,000 and having epoxy groups at both ends of the molecule; A resin component and (b) a liquid acrylonitrile-butadiene copolymer component having 1.7 to 3 amino groups per molecule are combined so that the amount of active hydrogen in the amino group is 0.5 to 2.0 equivalents per equivalent of epoxy group. This is achieved using a two-part epoxy coating composition. The epoxy resin used in the present invention is a high molecular weight modified epoxy resin that has been modified with dimer acid or nitrile rubber, has epoxy groups at both ends of the molecule, and has a molecular weight of 2,000 to 10,000. Epoxy resins modified with dimer acids obtained by heat-polymerizing unsaturated fatty acids and the like are known, and various dimer acid-modified epoxy resins are commercially available. For example, Epotote YD-172 (Toto Kasei, trade name), Epicron 1600 (Dainippon Ink Chemical Co., Ltd.,
(trade name), Haripol 341-60 (Harima Kasei Kogyo, trade name), but in the present invention, only those with a high molecular weight of 2,000 to 10,000, such as Haripol 341-60, are selectively used. . Also, butadiene with a carboxyl group at the end
Epoxy resins modified with acrylonitrile copolymers are also used, for example, in JP-A-55-84371 and JP-A-56-84371.
It is described in No. 122823, etc., and Epotote YR-
207, Epotote YR-102 (Toto Kasei, product name)
There are various commercial products such as However, in the present invention, among them, those having a high molecular weight of 2,000 to 10,000, such as Epotote YR-102, are selectively used. If the molecular weight of the above-mentioned modified epoxy resin is less than 2000, a large amount of curing agent is required, and a long enough pot life for concrete painting, for example, 2 to 3 hours, cannot be obtained, and the desired coating film performance may not be obtained. If it exceeds 10,000, the reactivity with the crosslinking agent decreases and the viscosity becomes too high, making it unsuitable for the purpose of the present invention. A particularly preferred molecular weight range is 2000-5000. In the present invention, the above dimer-modified epoxy resin, nitrile rubber-modified epoxy resin, or a mixture thereof has amino groups per molecule,
It is characterized in that it can be used in combination with a liquid acrylonitrile-butadiene copolymer having 1.7 to 3 copolymers. A liquid acrylonitrile-butadiene copolymer having 1.7 to 3 amino groups per molecule is used, for example, in combination with a low molecular weight epoxy resin to obtain adhesives, etc., as described in Japanese Patent Publication No. 60-3407. It is a known curing agent. In the present invention, such a copolymer of acrylonitrile and butadiene has an average of 2 amino groups in the molecule, preferably at both ends of the molecule, and has a molecular weight of 1000 to 1000.
About 4000 are used, for example, hikers
ATBN1300×16, 1300×218 (BF Gutsudoritsuchi,
Commercially available products such as (trade name) can be suitably used. The modified high molecular weight epoxy resin and the amino group-containing liquid acrylonitrile-butadiene copolymer have an amount of active hydrogen of the amino group per equivalent of the epoxy group.
They are combined at a ratio of 0.5 to 2.0 equivalents and used as a two-component coating composition. The present inventors found that among the above-mentioned polymer-modified epoxy resin curing agents, only the liquid acrylonitrile-butadiene copolymer, which has 1.7 to 3 amino groups per molecule, with an average of 2 amino groups, sufficiently follows cracks in concrete. The ratio of the epoxy resin to the curing agent is such that the ratio of the epoxy resin to the curing agent is such that it can provide a high elongation rate, for example, 100% or more, and can provide a coating film with sufficient curing and coating performance desirable for preventing concrete deterioration.
The amount of active hydrogen in the amino group must be 0.5 to 2.0 equivalents, preferably 0.5 to 1.5 equivalents, per 1 equivalent of epoxy group. If it is less than 0.5 equivalents, the elongation rate will be insufficient and the tensile strength will be insufficient due to insufficient curing. However, it was found that the water resistance, chemical resistance, etc. deteriorate, and even if the amount exceeds 2.0 equivalent, the curing property is extremely poor, making it impractical. In the present invention, which satisfies the above requirements,
Because a relatively high molecular weight epoxy resin and a high molecular weight specific curing agent are used, sufficient barrier properties are obtained even in the early stages of the reaction, and the cured coating film has excellent water resistance, alkali resistance, and adhesion. In particular, we have found that the elongation rate is extremely high, 150% or more or even 400%, and that it has sufficient ability to follow concrete cracks and has high tensile strength, making it extremely suitable for the purpose of preventing concrete deterioration. This completes the present invention. In the coating composition of the present invention, the above-mentioned epoxy resin component and curing agent component are separately prepared together with a solvent if desired, and the two are mixed before use, and sprayed.
It is applied to a concrete surface by a conventional application method such as a roller or brush, and the curing reaction is allowed to proceed at room temperature. Moreover, the coating composition of the present invention is characterized by having a long pot life of, for example, 2 to 3 hours, which is sufficient for painting operations when the two components are mixed, thereby providing an extremely practical coating composition. In addition to the above-mentioned essential components, the composition of the present invention may optionally contain pigments, additives such as dispersants, thixotropic agents, plasticizers, resins, etc. They can also be used together. In particular, the inventors have found that flaky substances such as glass flakes, mica, scaly iron oxide, aluminum powder, etc.
It has also been found that significant improvements in water resistance and barrier properties can be achieved by adding it in an amount that does not significantly affect membrane performance. Furthermore, for the purpose of further improving weather resistance, aesthetic appearance, etc., a top coating material such as urethane or fluororesin may be applied if desired. Therefore, the composition of the present invention is not only extremely useful as a deterioration prevention coating for concrete, but also extremely useful as a chipping-resistant coating for automobiles, a protective coating for marine structures, and the like. The present invention will be explained below with reference to Examples. Example 1 Haripol 341-60 (dimer acid-modified epoxy resin varnish, solid content 60%, epoxy equivalent 2000, Harima Kasei Kogyo, trade name) 36 parts, titanium oxide 11 parts, talc 15 parts, Baryta 15 parts, xylene 7 parts Evenly disperse and mix with 3 rolls, then Hiker ATBN1300
Added ×16 ^* 16 parts and adjusted the paint. The equivalent ratio of the epoxy group to the active hydrogen of the amino group in this coating composition was 1:1, and the pot life was 3 hours. The above paint was applied with a brush to a concrete wall, a sandblasted steel plate, and a tin plate to a dry film thickness of 150 μm, and left to stand to obtain a cured paint film. Butadiene-acrylonitrile copolymer represented by, molecular weight 3400, viscosity 225000 cps (27℃) BF Gutdrich, trade name Hiker
ATBN1300×16 Examples 2 to 4 and Comparative Examples 1 to 3 The same method as in Example 1, but with the exception of
-60 and Hiker ATBN 1300 x 16 by changing the blending amount as shown in Table 1 to obtain a coating composition,
It was applied to concrete walls, sandblasted steel plates and tin plates as in Example 1 to obtain cured coatings. Examples 5-6 Instead of Haripol 341-60, Epototo YR-102-60 (epoxy equivalent weight 1100-1300, Toto Kasei, trade name, solid content), a nitrile rubber-modified epoxy resin, was used.
60%) at the compounding ratio shown in Table 1, a coating composition was obtained in the same manner as in Example 1, and a cured coating film was also obtained. Comparative Examples 4 to 7 Coating compositions were obtained in the same manner as in Example 1, except that the types of epoxy resin and curing agent were changed and the mixing ratios shown in Table 2 were used to obtain cured coating films. Regarding the cured coating films of the above examples and comparative examples,
Performance tests were conducted as shown below, and the results are shown in Table 1.
It is shown in Table 2. Curing property: Painted on a concrete wall to a dry film thickness of 150μ, painted at 20°C, dried for 24 hours, and evaluated by pressing with a finger to see how hard a fingerprint remained. × Does not harden △ Some residue ○ Almost no residue Water resistance...The paint film does not blister or rust after 7 days of immersion in 40℃ tap water. It was applied to a sandblasted steel plate with a brush to a thickness of 150 μm (dry film thickness), dried at 20°C for 7 days, and then tested. Alkali resistance...40℃ 3% NaOH aqueous solution immersion 3
Blistering of the membrane after several days. (The coated board is the same as water resistance) Elongation rate Tensile strength... Painted on a tin plate at 20℃, after drying for 7 days, a 150μ free film was created using the mercury amalgam method, and the free film was heated to 60℃.
After drying for one month, a sample was prepared according to JIS K-6734, and the elongation rate and tensile strength until membrane breakage were determined at a tensile speed of 20 mm/min.

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Claims (1)

[Scope of Claims] 1 (a) a dimer acid-modified epoxy resin and/or nitrile rubber-modified epoxy resin component having a molecular weight of 2,000 to 10,000 and having epoxy groups at both ends of the molecule; (b) an amino group per molecule; A two-component epoxy coating composition comprising 1.7 to 3 liquid acrylonitrile-butadiene copolymer components in such a manner that the amount of active hydrogen in the amino group is 0.5 to 2.0 equivalents per 1 equivalent of the epoxy group.