JPH11310734A - Anticorrosive epoxy resin coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an anticorrosive epoxy resin coating composition having a high coefficient of slip and good workability as well as excellent anticorrosiveness and workability inherent in an organozinc-rich coating material by selecting a coating composition which can give a coating film having a specified or large amount of a zinc powder and having a specified or larger coefficient of slip. SOLUTION: The coefficient of slip of the coating film can attain 0.4 or above by incorporating at least 91 wt.% zinc powder in the coating film. The zinc used is not particularly liminted. The mean particle diameter of the zinc powder is, usually, 1-30 μm, desirably, 2-10 μm. The binder used may be an epoxy resin. The curing agent used for the epoxy resin is exemplified by an aliphatic polyamide, an aromatic polyamide, or an alicyclic polyamide. The coating composition may optionally contain an extender pigment, a coloring pigment, an antisaggant, an antisettling agent, an organic solvent, etc. After being diluted with a suitable solvent, the composition is applied by e.g. airless spraying, air spraying, or brushing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin anticorrosion paint composition having a high slip coefficient, which is used for bolted joints of large steel structures.

[0002]

2. Description of the Related Art Conventionally, as anticorrosion paint for large steel structures,
Organic zinc-rich paints and inorganic zinc-rich paints using zinc dust as rust preventive pigments are used.

[0003] Organic zinc-rich paints and inorganic zinc-rich paints, which contain zinc dust as a rust-preventive pigment, are used in large steel structures as paints having excellent anticorrosion properties, and are widely known as undercoat paints especially for bridges. ing. The anticorrosion effect of these paints is to bring about an anticorrosion effect by the sacrificial anodic action of zinc by electrochemical action when the iron base and the zinc dust in the coating film come into contact.

[0004] The anticorrosion effect of zinc is as follows.
The effect is sufficiently exhibited when the content is about 90% by weight, and the content of zinc powder in this range is sufficient in terms of anticorrosion properties.

[0005]

Organic zinc-rich paints and inorganic zinc-rich paints are widely used as anticorrosion paints for large steel structures, but each has advantages and disadvantages. For example, inorganic zinc-rich paint has the advantage of a large slip coefficient at the bolted joint, but the workability is very difficult because cracks are apt to occur when the film thickness is thick, and it takes a lot of man-hours for rework. have.

On the other hand, since the organic zinc-rich paint is based on an epoxy resin, the workability is good, and there is an advantage that cracks do not occur even when the film thickness is increased.
Since the slip coefficient is as small as 0.3 to 0.35, it has a disadvantage that it is not used for a bolted joint.

The slip coefficient of a steel bridge structure at a bolted joint is specified to be 0.4 or more in the specification and description of road bridge (published by Japan Road Association).

[0008] Organic zinc-rich paints are
It has the same performance as inorganic zinc-rich paint, and since cracks do not occur even when the film thickness increases, it has a performance higher than that of inorganic zinc-rich paint in terms of workability. Difficult to apply due to small slip coefficient.

For this reason, an inorganic zinc-rich paint having a slip coefficient of 0.4 or more is used for the bolted joints, and the other parts are separately painted with an organic zinc-rich paint having good workability. In the case of this construction method, there is a problem that an extra painting step is required.

The present invention relates to an epoxy resin anticorrosion paint composition which solves the problem of slip coefficient without impairing the excellent anticorrosion property and workability of the conventional organic zinc-rich paint as described above. is there.

According to the present invention, the conventional problem of selectively using an organic zinc-rich paint and an inorganic zinc-rich paint is eliminated by applying an organic zinc-rich paint having a large slip coefficient and good workability. Shortening of man-hours and cost reduction are expected.

[0012]

Means for Solving the Problems The present inventors have conducted intensive studies on various compounds in order to develop an anticorrosive coating composition having a large slip coefficient. As a result, the coating film contained at least 91% by weight of zinc dust in the coating film. The anticorrosion coating composition obtained has a slip coefficient of 0.1.
We found that we could get more than 4 results. That is, the present invention is an epoxy resin anticorrosion coating composition comprising zinc powder in a coating film in an amount of 91% by weight or more and a slip coefficient of the coating film of 0.4 or more.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As a method for increasing the slip coefficient, several points can be considered. In the present invention, the amount of zinc dust in a coating film, which was conventionally 70 to 90% by weight, is further reduced by 91%. It has been found that the slip coefficient is increased to 0.4 or more by increasing the weight% or more.

The zinc powder used in the present invention is not particularly limited, and various powders can be used. The average particle size of the zinc powder is usually 1 to 30 μm, preferably 2 to 10 μm, but is not limited thereto.

An epoxy resin is used as a binder in the anticorrosion coating composition of the present invention. The epoxy resin to be used is not particularly limited, and various types may be used. Epoxy 828, 834, 10
01 etc. are mentioned as an example.

The curing agent for the epoxy resin is not particularly limited, and examples thereof include aliphatic polyamides, aromatic polyamides, and alicyclic polyamides.

The epoxy resin anticorrosive coating composition of the present invention may further comprise an extender pigment, a coloring pigment, a sagging agent,
An anti-settling agent, an organic solvent and the like can be blended.

The epoxy resin anticorrosion coating composition of the present invention comprises:
The above zinc dust, epoxy resin and other components can be produced by a known production method. The epoxy resin anticorrosion coating composition can be diluted with an appropriate solvent and applied by a known method, for example, airless spray, air spray, brush coating, or the like.

[0019]

Next, the present invention will be described specifically with reference to examples and comparative examples, but the present invention is not limited to these examples. In this specification,% is based on weight unless otherwise indicated.

Examples 1 and 2 and Comparative Example 1 shown in Table 1
Obtained by sufficiently dispersing the compositions No. 2 to No. 2. Comparative Example 3
Is an inorganic zinc-rich paint with a large slip coefficient.
Used commercially available one

[Slip Coefficient Measurement Test] The material of the test specimen was SS400 for both the base material and the attached plate.
5 or more. The paints shown in Table 1 are applied on both sides using an air spray to a dry film thickness of 75 μm and dried for 7 days. Then high-strength bolt (F10T, dimensions: 2
0x80) and tighten. The measurement of the slip coefficient is performed 24 hours after the bolt is tightened.・ Load specimens gradually so that slip points can be clearly identified.・ The slip point is confirmed at the point where the marking line of the test specimen is shifted and the point where the pointer of the tensile tester sharply decreases.

[Corrosion prevention test of zinc rich paint] The paints of Examples 1 and 2 and Comparative Examples 1 to 3 were applied to a sandblasted steel plate by air spray so that the dry film thickness became 75 μm, and dried at room temperature for one week. did.

The corrosion prevention test was performed by measuring the area ratio (%) of rust generated after 1000 hours of the salt spray test, and the evaluation was performed according to the following criteria. 10: Rust generation 0% 8: Rust generation less than 1% 6: Rust generation 1-3% 4: Rust generation 4-10% 2: Rust generation 11% or more

The results of the anticorrosion test are shown in Table 1.

[0025]

[Table 1]

(Note 1) Epoxy resin varnish: Etoto 1001 manufactured by Toto Kasei Co., Ltd. was used. (Note 2) Hardener varnish: Tomide 215 of Fuji Kasei Kogyo Co., Ltd. is used. (Note 3) Composition of commercially available inorganic zinc-rich paint Ethyl silicate resin varnish 15.0 Zinc dust 70.0 Talc 4.0 Sag stop agent 4.0 IPA 7.0 Total 100.0

[Test for confirming paint film defect (crack occurrence) of zinc rich paint] The paints of Examples 1 and 2 and Comparative Examples 1 to 3 were applied to a sandblasted steel plate, and the dry film thickness was 50 to 75 µm.
5 to 100 μm, 100 to 125 μm, 125 to 150
The coating was performed by air spray so as to have a thickness of 150 μm or more, and dried at room temperature for one week.

The coating film defect test was performed by observing the state of cracks generated on the coating film surface after drying for one week, and the evaluation method was performed according to the following criteria. XX: Cracks generated at 50 to 100 μm X: Cracks generated at 100 to 125 μm Δ: Cracks generated at 125 to 150 μm ：: No cracks were observed at 150 μm or more

Table 1 shows the results of the coating film defect (crack generation) test.

As is clear from these test results,
Examples 1 and 2, which are the coating compositions of the present invention, have a slip coefficient of 0.4 or more, and have excellent corrosion resistance and a coating film performance that does not cause cracks even when the film thickness is increased. .

[0031]

As is apparent from the present invention, zinc powder is added to 91
The epoxy resin anticorrosion coating composition of the present invention containing not less than% by weight has a slip coefficient of 0.4 or more, and has a feature that a large slip coefficient, which cannot be obtained with conventional organic zinc-rich paints, can be obtained.

Claims (1)

[Claims] 1. An epoxy resin anticorrosion coating composition comprising at least 91% by weight of zinc dust in a coating film and a slip coefficient of the coating film of 0.4 or more.