JPH1135882A - Anticorrosion paint composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition, capable of manifesting corrosionproof and rust preventing effects for a long period without causing coating film defects such as peeling or cracking even by an instantaneous temperature change and useful for a back surface, etc., of the bottom of a cargo tank for transporting vegetable oils having a high pour point by including a specific amount of a flexible epoxy resin therein. SOLUTION: This composition is obtained by including a flexible epoxy resin (solid content) (a polyethylene glycol glycidyl ether type, a glycidyl ether type of a bisphenol A alkylene oxide adduct, etc.), in an amount of 1-30 wt.%, preferably 3-25 wt.% based on the total resin solid content and further including a binder and an organic solvent, as necessary, a color pigment, an extender pigment, a suspending agent, an antisagging agent and a cissing preventing agent therein. The resultant composition is capable of providing >=50 deg.C, preferably >=70 deg.C Tg after coating and >=10%, preferably >=12% elongation of a coating film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anticorrosion coating composition, and more particularly to a back surface (a ceiling of a ballast tank) of a cargo tank of a carrier for carrying animal and vegetable oils having a high pour point such as heavy fuel oil C and palm oil having a high viscosity. The present invention relates to an anticorrosion paint composition capable of forming a long-term anticorrosion coating film suitable for use in a place where an instantaneous temperature change occurs, such as surface (2).

[0002]

2. Description of the Related Art Conventionally, tar epoxy resin coating JIS is usually provided on a ceiling surface of a ballast tank which is a back surface of a bottom portion of a cargo tank of a carrier ship for transporting animal and vegetable oil having a high pour point.
Two or one equivalents are coated with a dry film thickness of 200 to 250 μm. Also, recently, the modified epoxy resin paint is often applied with a dry film thickness of 250 to 300 μm.

[0003] Heavy fuel oil or palm oil has a high viscosity at room temperature and has poor fluidity. Therefore, when loading and unloading, it is necessary to heat the luggage to lower the viscosity and improve workability. Is normal. The heating temperature is often about 50 to 70 ° C, but may be 80 ° C or more. When such a high-temperature object is loaded, the temperature of the ceiling surface of the ballast tank (the back surface at the bottom of the cargo tank) also rises to the same level as the load. After unloading, seawater is injected into the ballast tank, but the seawater in winter is cold and may be 5 ° C or less. By injecting seawater into the ballast tank, the tank is rapidly cooled.

[0004]

Thus, the loading,
By unloading and repeatedly injecting water into the ballast tank, the ceiling surface of the ballast tank is in the range of 80 ° C to 5 ° C.
Occasionally, an instantaneous temperature change from 80 ° C. or more to 5 ° C. or less causes the coating film to be exposed to an environment in which the film is greatly expanded and contracted. Therefore, there is a problem that a coating film obtained by using a usual coating material for ballast tanks causes coating film defects such as peeling and cracking at an early stage, and corrosion and rust easily occur. The present invention is to solve the above-described problems, and an object of the present invention is to form a coating film that exhibits anti-corrosion and anti-rust effects over a long period of time even under the above-described environment. It is to provide a coating composition which can be used.

[0005]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have formulated a specific amount of a flexible epoxy resin in an anticorrosion coating composition, and applied it after coating. The inventors have found that the above objects can be achieved by limiting the Tg value and elongation percentage of the film to specific values, and have reached the present invention. That is, in the anticorrosion coating composition of the present invention, the flexible epoxy resin (solid content) accounts for 1 to 30% by weight of the total resin solids, and the Tg of the coated film after coating becomes 50 ° C. or more, The film is characterized in that the elongation percentage is 10% or more.

[0006]

Embodiments of the present invention will be described below in detail. Examples of the flexible epoxy resin that can be used in the anticorrosion coating composition of the present invention include polyethylene glycol glycidyl ether type, polypropylene glycol glycidyl ether type, glycidyl ether type of bisphenol A alkylene oxide adduct, and bisphenol A polymerized fatty acid adduct. Typical examples include various epoxy resins of glycidyl ether type and diglycidyl dimer acid type, and mixtures of two or more of these, but are not limited thereto.

The anticorrosion coating composition of the present invention contains the above-mentioned flexible epoxy resin as an essential component, and further contains the same components as those used in conventionally known anticorrosion coating compositions. . That is, the anticorrosion coating composition of the present invention, in addition to the flexible epoxy resin, an amine-cured epoxy resin, an isocyanate-cured polyol resin, a chlorinated resin,
Binders such as coumarone indene resin, vinyl chloride resin, xylene resin, ketone resin, petroleum resin, bitumen such as coal tar pitch and swollen charcoal, or a binder such as a mixture of two or more thereof, and aromatics such as xylene and toluene It can contain organic solvents such as aromatic hydrocarbons, alcohols and ketones, and if necessary, coloring pigments such as titanium oxide, iron oxide and carbon black, extenders such as talc, calcium carbonate, barium sulfate and mica In addition, various additives such as an anti-settling agent, an anti-flow agent, and an anti-cissing agent can be contained.

In the anticorrosion coating composition of the present invention, the flexible epoxy resin (solid content) is 1 to 30% by weight, preferably 3 to 2% by weight of the total resin solids including the flexible epoxy resin.
Accounts for 5% by weight. When the content of the flexible epoxy resin (solid content) is less than 1% by weight of the total resin solid content, the effects intended in the present invention become insufficient, which is not preferable. Conversely, if the content exceeds 30% by weight, the coating film does not have sufficient physical strength, and the tendency to cause coating film defects is undesirably increased.

The anticorrosion coating composition of the present invention has a Tg of 50 ° C. or more, preferably 70 ° C. or more after coating, and the elongation of the coating is 10% or more, preferably 12% or more. Things. If the Tg of the coating film after coating is less than 50 ° C., the coating film tends to deteriorate quickly in a high-temperature environment, which is not preferable. Further, when the elongation percentage of the coating film is less than 10%, it is not preferable because the coating film tends to have difficulty in relaxing the stretching stress due to an instantaneous temperature change.

[0010] The anticorrosion coating composition of the present invention may be applied directly to the surface of a steel material, for example, by degreasing and drying the surface of a shot blasted steel material, or by applying a shop primer to the surface of the steel material. May be painted, and then painted thereon. The anticorrosion coating composition of the present invention has a dry film thickness of 200 to
The paint is applied to a thickness of 500 μm, preferably 250 to 300 μm, and is naturally dried or forcibly dried at a temperature of 100 ° C. or less. As a coating method for applying the anticorrosive coating composition of the present invention, conventionally used methods such as brush coating, roller coating, air spray, airless spray, and electrostatic spray can be used as they are.

[0011]

The present invention will be described below in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. Of the components shown in Table 1 below, all components other than the polyamine resin and the polyamide resin component as the curing agent were kneaded for 2 hours in a sand mill in the amount (parts by weight) ratio shown in Table 1 to obtain each compound. Was prepared.
Then, immediately before coating, a polyamine resin or a polyamide resin component was mixed with the blended components in the amounts (parts by weight) shown in Table 1 to prepare an anticorrosive coating composition of the present invention.

Shot blast steel (JIS G 31)
01, 70 × 150 × 3.2 mm) was degreased with xylene and dried. On the surface of this steel material, each coating composition obtained above was dried by air spraying to a dry film thickness of 200 μm.
And dried naturally for 7 days. The obtained coated plate was subjected to a heat cycle test and a 90 ° C. salt water immersion test by the following methods.

<Heat cycle test>
The mixture was heated to 0 ° C. and then immersed in 5 ° C. ice water. After repeating this operation 10 times, the test plate was immersed in a container filled with a 3% by weight saline solution, kept at 60 ° C., and allowed to stand for one week. This operation was defined as one cycle, and the operation was performed for 15 cycles. <90 ° C. Salt Water Immersion Test> The test plate was immersed in a container filled with a 3% by weight saline solution, kept at 90 ° C., and allowed to stand for 4 months.

After the heat cycle test and the 90 ° C. salt water immersion test, the adhesion of the coating film was measured, and the appearance of the coating film was observed. Further, the rate of decrease in the adhesion of the coating film was determined from the adhesion of the coating film before the test and the adhesion of the coating film after the test. These were evaluated based on the evaluation criteria of Table 2 below. The results were as shown in Table 3 below. Further, the elongation percentage and Tg of each isolated coating film were measured, and the relationship with the coating film performance was grasped.

[0015]

[Table 1]

[0016]

[Table 2]

[0017]

[Table 3]

As is clear from the evaluation results shown in Table 3,
The coating compositions of Examples 1 and 2, which are the anticorrosion coating compositions of the present invention, have excellent anticorrosion properties and durability. On the other hand, the compounding amount of the flexible epoxy resin is 30% of the total resin solids.
The coating composition of Comparative Example 1 exceeding 10% by weight had insufficient physical strength of the coating film and could not withstand the heat cycle test and the 90 ° C salt water immersion test. Also, the coating composition of Comparative Example 2 in which the elongation percentage of the coating film was less than 10% was poor in heat cycle resistance, and the elongation percentage of the coating film was less than 10% and the Tg of the coating film was lower.
Is less than 50 ° C., both the heat cycle resistance and the 90 ° C. salt water immersion are poor, and the coating film has a Tg of 5
The coating composition of Comparative Example 4 having a temperature of less than 0 ° C. had poor salt water immersion at 90 ° C., which was not preferable.

[0019]

Industrial Applicability The anticorrosion coating composition of the present invention is an anticorrosion coating composition capable of forming a coating film capable of relaxing stretching stress due to temperature change and maintaining corrosion resistance for a long period of time. Suitable for painting places subject to instantaneous temperature changes.

Claims (1)

[Claims] In the anticorrosion coating composition, the flexible epoxy resin (solid content) accounts for 1 to 30% by weight of the total resin solids. An anticorrosion coating composition having a film elongation of 10% or more.