JP2001040279A - Anticorrosion fine solvent type epoxy resin coating composition - Google Patents

Abstract

[57] [Problem] To dilute a solvent with excellent long-term durability by suppressing the internal stress development of the coating layer itself due to solvent evaporation even if a solvent is added, suppressing the progress of corrosion and peeling from the wound part. To provide safe anticorrosion paints. (A) 100 parts by weight of a bisphenol-type liquid epoxy resin having an epoxy equivalent of less than 250 having two or more epoxy groups in one molecule as a main component of a coating material,
(B) monoglycidyl ether as a stress modifier in a range of 7 to
15 parts by weight, (c) 80 to 120 parts by weight as a pigment,
It is characterized in that (e) a modified amine curing agent based on isophoronediamine is compounded and used in a paint base agent mixed in a proportion of 5 to 30 parts by weight as a solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a severely corrosive environment such as a seawater introduction pipe, a circulating water pipe, an inner surface of a discharge pipe of a thermal power plant or a nuclear power plant, a splashing portion of an offshore structure, etc. The present invention relates to an epoxy resin coating composition exhibiting excellent effects of corrosion resistance and scratch resistance even when used in an environment that is easily damaged by work or driftwood.

[0002]

2. Description of the Related Art Conventionally, as an anti-corrosion coating which replaces a tar epoxy resin coating which is inferior in scratch resistance, such as an epoxy resin coating containing glass flakes or a polyester resin coating containing glass flakes, has excellent environmental barrier properties and coating hardness. Although a coating system and an ultra-thin film type epoxy resin coating having a thickness of 1 mm or more have been used, problems such as peeling of the coating material from the base and cracking of the coating material itself tend to occur.
As a countermeasure, use of a non-solvent type paint (JP-A-3-275781), which is an epoxy resin-based paint, which eliminates the need for a solvent without losing flexibility and ensures long-term durability. In order to increase the viscosity, a reactive diluent such as various monoglycidyl ethers and diglycidyl ethers has been used in combination.

[0003]

As a method for applying these paints, any of a brush, a roller, an airless spray, a two-component airless spray, etc. is used. However, the solvent type paint has a reduced viscosity when applied. In the coating process, the solvent volatilizes and the viscosity of the coating increases, so that flow characteristics suitable for coating are easily obtained. On the other hand, the solvent-free type paint has a large problem that, since the paintable time of the paint itself is short and the coating is difficult to apply, when a solvent is added, peeling occurs due to the generation of stress in the paint film itself due to evaporation of the solvent. Was. The present invention suppresses the development of internal stress in the coating layer itself due to solvent evaporation even when such a solvent is added, suppresses the progress of corrosion and peeling from scratches, and provides a solvent-dilutable heavy-duty anticorrosion coating with excellent long-term durability Is provided.

[0004]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have proposed a method for measuring the hardness of the coating film and the film thickness of the coating film in addition to the low shrinkage ratio, the low internal stress and the long-term corrosion resistance. Investigating the effects of various factors and conducting intensive studies including the design of the optimal paint and simulated experiments of the corrosive environment assuming the actual environment with the coating film many times, the result was that monoglycidyl ether was compared with epoxy resin. The present inventors have found that a coating composition containing a predetermined amount of a pigment, a solvent, and a modified diamine based on isophoronediamine as a curing agent is optimal, and completed the present invention.

That is, the present invention relates to (a) 100 parts by weight of a bisphenol-type liquid epoxy resin having two or more epoxy groups in one molecule and having an epoxy equivalent of less than 250 as a main component of a paint, and (b) stress modification. 7 to 15 parts by weight of a monoglycidyl ether as an agent;
(E) a modified amine curing agent based on isophoronediamine is blended with a paint base blended in a proportion of 120 parts by weight and (d) 5 to 30 parts by weight as a solvent. It is an epoxy resin coating composition for anticorrosion.

The mixing ratio Δe of the NH group (active hydrogen) equivalent in the modified amine curing agent (e), the epoxy equivalent in the main agent (a) and the epoxy equivalent in the stress modifier (b) in the present invention. / (A + b)} is 1 / 1.0 to 1 / 1.4
(Molar ratio) is preferably adjusted.

[0007]

Embodiments of the present invention will be described below in detail. First, regarding the basic composition of the epoxy paint, the epoxy resin as the main agent (a) may be a normal epoxy resin having two or more epoxy groups in one molecule capable of forming a crosslinked coating film. A liquid resin having an epoxy equivalent of about 150 to 250 can be used. If the epoxy equivalent is 250 or more, it becomes highly viscous and hinders the painting operation. If the epoxy equivalent is 150 or less, the crosslinking density is increased and the strength of the coating film is increased, which is not preferable.

In the present invention, the monoglycidyl ether as the stress modifier (b) is added in an amount of 5 to 15 parts by weight, particularly preferably 8 to 12 parts by weight, based on 100 parts by weight of the above main agent (a). When the amount is less than 5 parts by weight, the effect of reducing the stress is not recognized. On the other hand, when the amount is more than 15 parts by weight, the solvent hardly evaporates at the time of diluting the solvent, and the anticorrosive property is reduced. The reason why the anticorrosion performance is improved in the present invention is that the compatibility between the crosslinked resin of the main agent (a) and the modifier (b) is extremely good, so that the curing shrinkage of the coating film is reduced, It is considered that the secondary adhesion between the coating film and the iron surface is improved as a result of the effect of reducing the internal stress by reducing the ratio.

The base material (a) of the present invention may contain a predetermined amount of the pigment (c). The pigment (c) can be selected from color pigments, extenders and rust-preventive pigments. Examples of the coloring pigment include inorganic coloring pigments such as titanium oxide, carbon black, and red iron oxide, and organic coloring pigments such as azo, cyanine, and quinacridone. Examples of the extender include talc, calcium carbonate, barium sulfate, clay, silica, mica and the like. Further, scaly pigments such as stainless steel and MIO can be used. Examples of the rust-preventive pigments include zinc oxide and phosphomolybdenum which form a rust-preventive coating layer with a stable compound, such as zinc oxide and strontium chromate, which are oxidative rust-preventive pigments, such as alkaline pigments such as lead oxide and lead tin. Zinc acid, aluminum phosphate, and the like.

The mixing ratio of the pigment to the vehicle is not particularly limited. However, in the case of the extender which affects the anticorrosion, for example, 80 to 12 parts by weight based on 100 parts by weight of the base material (a).
The content is preferably in the range of 0 parts by weight. This is because the water vapor transmission rate of the coating film, which is a measure of the anticorrosion property, is minimized within the range of the blending ratio of the extender. On the other hand, in the case of a coloring pigment, it can be blended in an appropriate ratio according to a desired degree of coloring, but is generally in the range of 0 to 1000 parts by weight based on the resin component in the main agent (a).

The solvent (d) can be diluted with the solvent in an amount of 5 to 30 parts by weight based on 100 parts by weight of the main ingredient. When the amount of the solvent (d) is less than 5 parts by weight, the curing speed is high and the coating operation is difficult, and when the amount is more than 30 parts by weight, the solvent is difficult to evaporate and the anticorrosion property is reduced. As the solvent (d), an aromatic solvent, an alcohol solvent, a ketone solvent or the like having a relatively low boiling point, which hardly remains in the coating film after coating, is preferred. Examples of the aromatic solvent include toluene and xylene, examples of the alcohol solvent include ethanol, isopropanol, butanol, and isobutanol; examples of the ketone solvent include methyl ethyl ketone (MEK) and methyl isobutyl ketone.
These mixed solvents can also be used.

As the curing agent (e), a modified amine based on isophoronediamine is used. Here, as the modified amine based on isophoronediamine, those obtained by modifying isophoronediamine with an epoxy resin, those modified by Mannich, those modified by adduct alone, or mixtures thereof can be preferably used. . In the present invention, metaxylene diamine, aliphatic polyamidoamine, 100 parts by weight of the modified amine based on isophoronediamine,
Amines 1 selected from epoxy-modified meta-xylene diamine, aliphatic polyamidoamine epoxy-modified products, etc.
What blended 100 parts by weight can also be used.

[0013] The amount of the curing agent to be used at the time of use is determined by the NH group (active hydrogen) equivalent in the modified amine curing agent (e), the epoxy equivalent in the main agent (a), and the epoxy equivalent in the stress modifier (b). Compounding ratio {e / (a + b)} is 1 / 1.0 to
The two liquids are blended and adjusted so as to be 1 / 1.4 (molar ratio). In particular, this compounding ratio is 1/1.
1 / 1.2 is more preferred. Here, when the added amount of the curing agent is less than 1 / 1.4 (molar ratio), the degree of crosslinking of the coating film becomes insufficient, and when it is more than 1 / 1.0 (molar ratio). The hydrophilic amino group becomes excessive and water resistance is impaired.

[0014] The coating composition of the present invention may further contain various conventional additives. For example, additives such as a pigment dispersant, an antifoaming agent, a leveling agent, and an anti-sagging agent can be used. The thixotropic agent is added for the purpose of increasing the film thickness per coating, reducing the sagging of the coating film, further reducing the viscosity during coating and improving workability, and specifically, Polyethylene oxide, fatty acid amide wax, organic bentonite and the like are used.

The present invention can be applied, for example, as follows when using a two-pack type. That is, (a) the main component, (b) the stress modifier, and (c) a pigment and other various additives are mixed and dispersed at a predetermined ratio by a ball mill or the like to obtain a base main component. (C) A hardening agent can be prepared by mixing (c) a curing agent together with a solvent, for example, an aromatic or alcoholic solvent, and stirring and mixing.

The prepared heavy-duty anticorrosive paint is applied to an object to be coated, for example, a zinc-rich primer (JIS K
5552) or a thick-film type zinc-rich paint (JIS K5553) on a coated steel pipe or steel plate, for example, by airless coating so that the dry film thickness is about 200 to 800 μm, the coating film By curing, a desired coating film can be formed.

[0017]

The present invention will be described below in more detail with reference to examples and comparative examples. In addition, the evaluation of the coating materials performed in the following Examples and Comparative Examples was performed by performing a one-month acceleration test according to JIS K5400. The evaluation of each evaluation item is as follows. (1) The corrosion resistance was evaluated by the following salt spray resistance and moisture resistance.・ Salt water spray resistance was measured in accordance with JIS K5400 (9.1) salt water spray test, and ・ moisture resistance was measured in accordance with JIS K5400 (9.2) moisture resistance test in accordance with JIS K5400 (9.1), respectively, for 6 months. The presence or absence of appearance abnormalities such as blistering and peeling, and the cross-cut peeling resistance were evaluated. -Regarding cross-cut peel resistance, the peel width was evaluated as follows. ◎: extremely small, ○: small, △: large,
×: extremely large

(2) Adhesion was evaluated by the following adhesive strength. -Adhesive strength was measured according to ASTM D4541 at the initial stage and after 6 months of salt spray. The crosshead speed of the tensile tester was 5 (mm / min). (3) Regarding the airless coating available time, the coating viscosity is increased by the progress of the curing reaction of the coating, so that the coating time is limited. Therefore, the time from mixing the main agent and the curing agent at a liquid temperature of 20 ° C. to coating using an air-driven plunger pump (trade name, King 45: 1, made by GRACO) until coating becomes impossible is defined by the following criteria. Was evaluated. ◎: 2 hours or more, ：: Less than 2 hours to 1 hour, Δ:
Less than 1 hour to less than 0.5 hour, x: less than 0.5 hour

Example 1 First, an epoxy paint was prepared by the following method.
Epoxy resin as the main resin (Epotote YDF-170, epoxy equivalent 170, manufactured by Toto Kasei Co., Ltd.)
100 parts by weight, 11 parts by weight of monoglycidyl ether (manufactured by BTR, trade name: Heroxy WC-8 epoxy equivalent: 290) as a stress modifier, flat talc 95 as an extender
Parts by weight, 1 part by weight of carbon black as a coloring pigment, 10 parts by weight of titanium oxide, 6 parts by weight of toluene as a solvent, M
4 parts by weight of EK were mixed and dispersed by a disper to prepare a paint base agent. As a curing agent, epoxy-modified isophorone diamine (trade name, manufactured by Sanwa Chemical Co., Ltd., Sunmide IM)
-544) and blended with the above-mentioned paint base so that the blending amount of NH groups (active hydrogen groups) / epoxy groups of the main ingredient would be 1 / 1.2. The composition was prepared. The thus prepared coating composition was applied on a blasted steel sheet coated with a thick-film type zinc-rich paint (JIS K5553 type 1) by an airless coating machine so as to have a film thickness of 400 μm to prepare a test piece. Table 1 shows the results of the evaluation of the obtained paint by the evaluation method described above.

Example 2 Except that toluene was changed to 16 parts with respect to the paint,
A coating composition was prepared in the same manner as in Example 1, and similarly, a test piece was prepared by coating a blasted steel plate with an airless coating machine so as to have a film thickness of 400 μm. Table 1 shows the results of the evaluation of the obtained paint by the evaluation method described above.

Example 3 A coating composition was prepared in the same manner as in Example 1 except that the MEK was changed to 14 parts with respect to the paint, and a film thickness of 400 μm was formed on a blasted steel plate using an airless coater. Specimens were prepared by painting as described above. Table 1 shows the results of the evaluation of the obtained paint by the evaluation method described above.

Example 4 A paint was prepared in the same manner as in Example 1, and the film thickness was 800 μm.
A test piece similar to that of Example 1 was prepared except that the coating was performed so as to obtain an evaluation. Table 1 shows the compounding ratios and evaluation results of Examples 1 to 4.

[0023]

[Table 1]

Comparative Example 1 Without using monoglycidyl ether as a stress modifier,
The other conditions were adjusted in the same manner as in Example 1 to prepare the coating composition, and the evaluation was performed in the same manner.

Comparative Example 2 Monoglycidyl ether (manufactured by BTR,
Trade name of Heroxy WC-8 epoxy equivalent 290)
A coating composition was prepared in the same manner as in Example 1 except that the amount was changed to 0 parts by weight, and the evaluation was performed in the same manner.

Comparative Example 3 A coating composition was prepared in the same manner as in Example 1 except that the amount of flat talc was changed to 60 parts by weight, and the same evaluation was performed. The results are shown in Table 2.

Comparative Example 4 A coating composition was prepared in the same manner as in Example 1 except that the flat talc was changed to 140 parts by weight and the film thickness was changed to 800 μm. Show.

Comparative Example 5 A coating composition was prepared in the same manner as in Example 1 except that the amount of toluene was changed to 1 part by weight and the amount of MEK was changed to 1 part by weight. .

Comparative Example 6 A coating composition was prepared in the same manner as in Example 1 except that monoglycidyl ether was changed to 20 parts by weight and toluene to 30 parts by weight. It is shown in FIG.

Comparative Example 7 A coating composition was prepared in the same manner as in Example 1 except that MEK was changed to 30 parts by weight, and the same evaluation was performed. The results are shown in Table 2.

Comparative Example 8 An epoxy-modified isophoronediamine (manufactured by Sanwa Chemical Co., Ltd., trade name: Sunmide IM-544) was used as a curing agent, and the compounding amount of NH group (active hydrogen group) / epoxy group of the main component was adjusted. The coating composition was adjusted to 1 / 1.6 (molar ratio) with the coating base of Example 1 and mixed by stirring to prepare a coating composition. The results of the evaluation are shown in Table 2.

Comparative Example 9 Epoxy-modified isophoronediamine (manufactured by Sanwa Chemical Co., Ltd., trade name; Sun-Matedo IM-544) was used as a curing agent, and the compounding amount of NH group (active hydrogen) / epoxy group of the main component was 1 /0.9 (molar ratio) was blended with the paint base agent of Example 1 and mixed by stirring to prepare a paint composition. The results of the same evaluation are shown in Table 2.

[0033]

[Table 2]

[0034]

According to the epoxy resin coating composition of the present invention, since the compatibility between the crosslinked resin of the main component (a) and the modifier (b) is extremely good, the curing shrinkage of the coating film can be reduced or The effect of reducing the internal stress by lowering the coating film elastic modulus is exhibited. This suppresses the internal stress development of the coating layer itself due to solvent evaporation, suppresses the progress of corrosion and peeling from the scratched part, and has excellent long-term durability. In an environment that is easily damaged by shellfish work or driftwood, an effect excellent in corrosion resistance and scratch resistance can be exhibited.

Continuing on the front page (72) Inventor Hiroshi Fukai 7-21-11 Nishi Gotanda, Shinagawa-ku, Tokyo Inside Nippon Steel Chemical Co., Ltd. (72) Inventor Hiroshi Kido 7-21-11 Nishi-Gotanda, Shinagawa-ku, Tokyo New Nippon Steel Chemical Co., Ltd. (72) Inventor Kazumasa Kobayashi 7-21-11 Nishigotanda, Shinagawa-ku, Tokyo Nippon Steel Chemical Co., Ltd. (72) Inventor Masami Ishida 2-6-Otemachi, Chiyoda-ku, Tokyo No. 3 Inside Nippon Steel Corporation (72) Inventor Yoichi Ito 5-3 Tokaicho, Tokai City, Aichi Prefecture Inside Nagoya Works, Nippon Steel Corporation (72) Inventor Kotaro Yoshida Otemachi 2 Chiyoda-ku, Tokyo No. 6-3 New Nippon Steel Corporation F-term (reference) 4J036 AD01 DC09 FA01 FA03 FA05 FA11 FA12 FB13 JA01 4J038 DB061 GA07 JA69 JB04 KA03 KA06 KA08 MA07 NA03 PB05

Claims (2)

[Claims] 1. (a) As a main component of a coating material, 2 per molecule
100 parts by weight of a bisphenol-type liquid epoxy resin having an epoxy equivalent of less than 250 having at least two epoxy groups,
(B) monoglycidyl ether as a stress modifier in a range of 7 to
15 parts by weight, (c) 80 to 120 parts by weight as a pigment,
(E) an epoxy resin for heavy-duty anticorrosion, wherein (e) a modified amine curing agent based on isophoronediamine is compounded and used in a paint base agent mixed in a proportion of 5 to 30 parts by weight as a solvent. Paint composition. 2. The compounding ratio of the NH group (active hydrogen) equivalent in the modified amine curing agent (e) to the epoxy equivalent in the base material (a) and the epoxy equivalent in the stress modifier (b) Δe / ( a +
The heavy duty anticorrosion epoxy resin coating composition according to claim 1, wherein the composition is adjusted so that b)｝ is 1 / 1.0 to 1 / 1.4 (molar ratio).