JPH07766B2 - Coating composition and coating structure - Google Patents

Description

TECHNICAL FIELD The present invention relates to a coating composition and a coating film structure, and in particular to a tar epoxy resin coating composition or other coating film having a bleeding property, whereby bleeding (bleeding) occurs. The present invention relates to a coating composition and a coating film structure that suppress the phenomenon and impart good anticorrosion performance.

[Conventional technology]

Tar-epoxy resin paints exhibit reliable corrosion resistance for a long period of time against corrosion caused by seawater, fresh water, high humidity, etc., so they are widely used in bridges, steel pipes, cast iron pipes, ship outer plates, tanks in ships, oil tanks, steel plates. -Used for concrete, etc. However, since coal tar and bitumen are contained as main raw materials, it is usually limited to black or brown-black hues. In addition, tar epoxy resin paints have excellent adhesion, water resistance, impact resistance, thick coating properties, etc., and have a track record of more than 20 years. Tar and bitumen cause a bleeding phenomenon and turn brown, which makes overcoating impossible. When it is necessary to apply paint on the tar epoxy resin paint for coloring, etc., apply aluminum paint or MIO (mica-like iron oxide) -containing paint, and after drying, apply paint for coloring on it. The usual method was to suppress the bleeding of tar by the so-called maze effect of aluminum pieces or mica-shaped iron oxide. However, even with this method, even if the bleeding is suppressed immediately after coating, the bleeding cannot be suppressed after a few months, and tar causes bleeding in the top coating. Also, as mentioned above, tar epoxy resin paint has been widely used on the inner surface of road pier boxes, but its color is limited to black or blackish brown, and the lightness is low, so inspection at a place where light does not enter The work is dangerous. When actually inspecting the inner surface of the pier box, there is a strong request from the parties concerned to paint the inside of the box with highly bright paint to ensure the safety of the inspection work. In the new coating, it is possible to coat a paint (Japanese Patent Laid-Open No. 62-181359) that can be colored by blending a light-colored oligomer (synthetic tar) using a distillate from coal and petroleum as a raw material. However, the tar epoxy resin paint has already been applied, and when the paint color is brightened or repair work is performed, a bleeding phenomenon occurs and there is no means. On the other hand, Permanent Red 4R
Insoluble azo pigments such as (JIS K5209) are widely used for red, etc. as defined by JIS Z9104 General Rules for the Use of Safe Colored Light, because their primary color is red and their weather resistance is good.
However, the bleeding property is poor due to poor solvent resistance, and bleeding occurs when paint is applied repeatedly on a red paint film made using this pigment.For example, when white paint is applied repeatedly, it turns pink. Therefore, even if you try to change the color from the viewpoint of coating repeatability, it cannot be applied over the old paint film, and it is necessary to peel off the old paint film before painting. It was the current situation. Other than insoluble azo red pigments, pigments with poor bleeding resistance, such as green gold (COLOR INDEX PIGMEN
There are also metal complex pigments such as T YELLOW GREEN 10), and coating films using these pigments have been widely used because of their good weather resistance, but they were very difficult to repaint.

[Problems to be Solved by the Invention]

In view of the actual situation as described above, the present invention suppresses the bleeding phenomenon of the coating film by coating on the coating film having bleeding property, thereby enabling overcoating of any top coating composition, and also in corrosion resistance. Another object of the present invention is to provide a coating composition capable of obtaining an excellent coating film and a coating film structure having the composition as an intermediate coating layer.

[Means for Solving the Problems]

The present inventors have conducted extensive studies to solve the above problems, and as a result, have found completely new means for solving these problems all at once, and completed the present invention.

That is, the present invention provides (1) a coating composition containing a pigment and a vehicle as main components, wherein the coating composition essentially contains 0.5 to 30% by weight of activated carbon as a pigment in a solid content weight ratio. object.

(2) The pigment content is 15 to 60% by weight based on the solid content weight ratio,
The coating composition according to the above (1), wherein 0.5 to 30% by weight of the activated carbon is activated carbon.

(3) The coating composition according to (1) or (2) above, wherein the activated carbon has a specific surface area of 700 to 1700 m ² / g.

(4) An intermediate coating layer comprising a paint essentially containing 0.5 to 30% by weight of activated carbon as a pigment in a paint composition containing a pigment and a vehicle as main components. Coating structure.

(5) The pigment content is 15 to 60% by weight in terms of solid content weight ratio,
Further, the coating film structure according to (4) above, which has an intermediate coating film layer comprising a coating material in which 0.5 to 30% by weight is activated carbon.

(6) The specific surface area of activated carbon in the intermediate coating layer is 700-1700m
The coating film structure according to (4) or (5) above, which is ² / g.

Is.

Hereinafter, the present invention will be described in detail.

First, the composition of the present invention contains activated carbon as a pigment, and its main feature is a coating film structure for forming a coating film containing activated carbon as an intermediate coating film. It contains tar epoxy resin paint, insoluble azo pigment, and metal complex pigment, and if the paint is applied over from above due to poor solvent resistance, the paint composition containing activated carbon is applied on the paint film with bleeding property. By forming the intermediate coating film, bleeding can be suppressed even when the coating material is applied thereon. The reason is that activated carbon is carbon with innumerable fine pores inside it, as if it were a molecular magnet, with a specific surface area of 700 to 3000 m ² / g, which is extremely large compared to ordinary pigments, and adsorption of bleeding components. It is considered to act as an agent. By the way, the specific surface area of the coloring carbon black pigment which is the same carbonaceous material is 30 to 600 m ² / g, silica gel 200 to 600 m ² / g, alumina 150 to 350 m ² / g, activated clay 100
~ 200m ² / g, since synthetic zeolite 400 ~ 750m ² / g,
These are several to several hundred times.

The activated carbon used in the present invention is not particularly limited, but one having a specific surface area of 700 to 1700 m ² / g is preferable, and one having a specific surface area of 800 to 1200 m ² / g is particularly preferable. It is appropriate that these activated carbons be in powder form due to their suitability for coating, and Taiko activated carbon KAW (manufactured by Nimura Chemical Co., Ltd.), Umebee Ink Special, Umebee HC (manufactured by Taihei Chemical Industry), Shirasagi APC (Takeda Chemical Industry) Commercially available activated carbon such as those manufactured by K.K. can be used. It is essential that such activated carbon is contained as a pigment contained in the coating composition in an amount of 0.5 to 30% by weight in terms of solid content weight ratio, and particularly preferably in the range of 5 to 25% by weight. 0.
If it is less than 5% by weight, the effect of suppressing bleeding is small, and if it is more than 30% by weight, the viscosity of the coating is high and the suitability as a coating is poor. In this case, at least activated carbon is indispensable as the pigment component, and needless to say, it may be used alone, but in addition to this, the viscosity property is improved, an anti-settling effect is given, and a reinforcing effect of the coating film. One or more other pigments such as hydrous magnesium silicate, barium sulfate, aluminum silicate, and calcium carbonate may be used in combination for the purpose of giving In that case, the total content of the pigment content is 15 to 15 in terms of solid content weight ratio including the activated carbon.
A range of 60% by weight is preferable, and 20 to 30% by weight is particularly preferable.
If the total amount of pigments is less than 15%, the coating film will be in a thin state with no build-up effect, and the bleeding suppressing effect and reinforcing effect will be poor, while if it is more than 60% by weight, the coating viscosity will be high and the coating film will be brittle. It is also inferior in anticorrosiveness.

Next, the vehicle for paint used in the present invention is not particularly limited, and synthetic resin vehicles such as polyester, acrylic, alkyd, epoxy, vinyl chloride and vinyl butyral can be used, and melamine formaldehyde resin and phenol formaldehyde resin are appropriately used. A curing agent such as isocyanate resin and polyamide resin can be used together. In addition, fibrin such as nitrocellulose and cellulose acetate butyrate, dibutyl phthalate, dioctyl phthalate,
A plasticizer such as tricresyl phosphate can also be used in combination. The coating composition of the present invention is used in a state where its viscosity is adjusted by dissolving or / and dispersing it in water or an organic solvent. As the organic solvent, any one of hydrocarbon type, alcohol type, ether alcohol type, ether ester type, ketone type and the like, which has suitable coating property and drying property, can be used. If necessary, a surface smoothing agent, a dispersant, an anti-settling agent, a thixotropic agent, etc. can be added.

Examples of the present invention will be described below.

〔Example〕

(1) Preparation of paint The formulations shown in Table 1 were thoroughly stirred with a known stirrer and then dispersed with a three-roll mill to prepare a coating material.

The formulations shown in Table 2 were sufficiently stirred with a known stirrer and then dispersed with a roll mill to prepare a coating material.

(2) Preparation of test piece Tar epoxy resin paint Eposir No.200 (manufactured by Kansai Paint Co., Ltd.) JIS K5664 tar epoxy resin paint type 1 standard product on a steel plate with a thickness of 1 mm 250 g / m ² / coating interval 3 times per day It was applied once to form a panel having a coating film thickness of 240 to 250 μm and dried at room temperature for one month. A coating material prepared according to Table 1 was applied on the coating film so as to have a film thickness of 120 μm to obtain a test piece.

A coating material was prepared by thoroughly stirring with a known stirrer based on the following composition and then dispersing with a ball mill.

Alkyd resin varnish ^{* 10} 25 TCP ^{* 11} 10 Nitrocellulose ^{* 12} 21.4 Permanent Red 4R ^{* 13} 10 Toluene 13.6 Ethyl acetate 20 Butyl acetate 20 Total 100 (wt%) ^{* 13} Permanent Red 4R100 Fuji Dye Co., Ltd. Was coated on the steel sheet of No. 3 to a coating thickness of 30 to 40 μm and dried at room temperature for 3 days. The coating material prepared based on Table 2 was applied on the coating film so as to have a film thickness of 30 μm to obtain a test piece.

(3) Test method The paint made based on Table 1 is JIS K5664 tar epoxy resin paint, and the paint made based on Table 2 is JIS K5664
Evaluation was performed based on the test method specified for 5531 nitrocellulose lacquer. Regarding the bleeding property, the paints produced in the examples are black and it is difficult to evaluate and evaluate. Therefore, the white paints produced in Comparative Examples 3 and 4 were further applied and evaluated.

The results are shown in Tables 3 and 4. ○: good ×: bad [Effects of the Invention] According to the present invention as apparent from the above examples, by applying on a coating film having bleeding property, bleeding is suppressed, and thereby, the overcoating of any topcoat paint can be performed. It is possible to provide a coating composition having good corrosion resistance and a coating film structure having the composition as an intermediate layer, and the practical effect is extremely remarkable.

Claims (6)

[Claims] 1. A coating composition comprising a pigment and a vehicle as main components, wherein the pigment content is 0.5 to 30% by weight in terms of solid content.
A coating composition comprising the activated carbon of 1. 2. The pigment content is 15 to 60% by weight based on the weight of the solid content, and 0.5 to 30% by weight thereof is activated carbon.
The coating composition described. 3. The coating composition according to claim 1, wherein the activated carbon has a specific surface area of 700 to 1700 m ² / g. 4. An intermediate coating film layer comprising a coating material essentially containing 0.5 to 30% by weight of activated carbon as a pigment in a coating material composition containing a pigment and a vehicle as main components. And the coating film structure. 5. The coating film structure according to claim 4, which has an intermediate coating film layer comprising a coating material in which the pigment content is 15 to 60% by weight based on the solid content, and 0.5 to 30% by weight thereof is activated carbon. . 6. The specific surface area of activated carbon in the intermediate coating layer is 700 to 1
The coating film structure according to claim 4 or 5, which is 700 m ² / g.