JPH0615219B2 - Colored polyolefin resin coated heavy corrosion resistant steel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a polyolefin resin-coated heavy-corrosion steel material used for structures used in the ocean, harbors, rivers, etc., foundation piles and earth stoppers. The present invention relates to a colored polyolefin resin-coated heavy corrosion-resistant steel material which is exposed in the air and used, is colored in various colors, is harmonious with the environment, and has excellent weather resistance.

(Prior Art and Problems to be Solved by the Invention) FIG. 2 is an explanatory view of a conventional heavy corrosion-resistant steel material having a polyolefin resin as an anticorrosion coating layer, in which 1 is a steel material, 2 is an inorganic primer layer, 3 is an organic primer layer, 4 is an adhesive layer, and 5 is a polyolefin coating layer.

Polyolefin resin coating of conventional steel pipe piles The color of the polyolefin resin coating layer of heavy corrosion-resistant steel is almost black, so the sign maintenance and aesthetic sense are not sufficient, and it tends to be inconsistent with the surrounding environment as a steel structure. was there. For this reason, the image of the product as a product is not good even though it has the characteristics of long-term corrosion resistance of steel, and consumers are demanding coloration. In response to these requirements, there is one disclosed in JP-A-61-172737, which is a urethane coating containing a urethane resin coated on a polyolefin resin heavy anticorrosion coating layer and containing a color pigment thereon. A method for coating a polyolefin resin, which comprises coating an acrylic urethane paint, an acrylic paint, an alkyd paint, an acrylic emulsion paint, a vinyl chloride paint, and a synthetic resin compounding paint. However, with the method for coloring a polyolefin resin produced by this method, it is difficult to maintain label preservation and aesthetic sense for a long period of time, the gloss of the coating film surface decreases with time, and fading deterioration is rapid.

(Means for Solving the Problems) In the present invention, the surface of a polyolefin resin layer is subjected to a fire treatment, and a urethane primer having adhesiveness with a polyolefin resin is preliminarily applied thereon in an amount of 5 to 20 μm. A colored polyolefin resin-coated heavy corrosion-resistant steel material, characterized in that a resin layer is provided.

As shown in FIG. 1, the present invention provides an inorganic primer layer 2, an organic primer layer 3, an adhesive layer 4, a polyolefin resin layer 5, a urethane primer layer 6 and a fluororesin layer 8 on the surface of a steel material 1. It is a heavy duty anticorrosion steel material coated with colored polyolefin resin.

The reason for using such a 6-layer type is that the inorganic primer layer 2, the organic primer layer 3, the adhesive layer 4, and the polyolefin resin layer 5 are used to enhance the adhesiveness, water resistance, impact resistance and insulation resistance, and The fire resistance of the resin layer 5 and the weather resistance of the urethane primer layer 6 and the fluororesin layer 8 are given special importance, and excellent performance is imparted to each. The suitable coating conditions for each of the six layers and the fire treatment are 30 for the inorganic primer layer 2 and the organic primer layer 3 in total.
˜60 μ, the adhesive layer 4 is 80 to 200 μ, the polyolefin resin layer 5 is 2 to 6 mm, the fire treatment temperature of the polyolefin resin layer 5 is 60 to 90 ° C., and the urethane primer layer 6 is 5
˜20 μ, and the fluororesin layer 8 is 10 to 100 μ.

Next, each layer will be described in detail.

In the present invention, the steel material to be lined is structural bristle steel,
Structural steel pipes made of high-tensile steel, weather resistant steel, sulfuric acid resistant steel, etc., steel pipe piles, and transportation pipes for water, oil, gas, etc. can be mentioned.

As a coating method, first, the anticorrosive surface of the steel material is cleaned by blasting such as grit blasting or sand blasting, and then the inorganic primer layer 2 and the organic primer layer 3 are used.
To cover.

These two primers are adhesives for maintaining long-term adhesion performance between the steel material surface 1 and the adhesive layer 4.

As the coating material, the inorganic primer layer 2 uses a chromic acid chemical conversion treatment agent, the organic primer layer 3 uses an epoxy primer coating, and is excellent in water resistance such as cathode peeling resistance and warm water resistance. Use one. The total thickness of the inorganic primer layer 2 and the organic primer layer 3 is 30 to 60 μm.
The range is appropriate.

The adhesive layer 4 is an adhesive for strengthening the adhesive performance between the organic primer layer 3 and the polyolefin resin layer 5, and the coating material uses a maleic anhydride-modified polyolefin adhesive and has a film thickness of Considering the coating performance and economical efficiency, 80 to 100 μ is suitable. The polyolefin resin layer 5 is a long-term anticorrosion layer. The coating material is a copolymer containing hydrocarbons such as ethane, ethylene and propylene as a main component, and a film thickness of 2 to 3 mm is suitable.

The urethane primer layer 6 is an adhesive between the polyolefin resin layer 5 and the fluororesin layer 8. The urethane primer layer 6 is composed of a polyol compound having a molecular weight of 400 to 2000 and containing two or more hydroxyl groups, and a polyisocyanate having two or more isocyanate groups in the molecule in an excess equivalent to the hydroxyl groups of the polyol compound. It is a urethane prepolymer containing a terminal isocyanate group obtained by reaction with a compound.

The coating film thickness should be 5 to 20μ, preferably about 5 to 10μ, and it is good to coat thinly by an air spray coating method. If the film thickness exceeds 20μ, it takes a long time to cure the coating film, and it seems that the coating film seems to be cured. Even if it looks like, the outer surface is hardened like a bark, the whole remains unhardened, and there is a problem that the adhesion performance with the fluororesin layer 8 is deteriorated because it is coated on it.

In addition, before coating the polyolefin resin layer 5 with the urethane primer layer 6, the surface temperature of the polyolefin resin layer 5 is preferably 60 to 90 ° C. by blowing a fire of a gas burner on the surface of the polyolefin resin layer 5. Is 70 ~
It is necessary to raise the temperature to 80 ° C. and partially oxidize the surface of the polyolefin resin layer 5 to create an activated state. It is preferable to keep the temperature rising time to about 5 minutes or less and to the time when the outer surface of the polyolefin resin layer 5 reaches the temperature described above, and when the polyolefin melts due to heat and is deformed, the surface becomes It deteriorates and the adhesiveness deteriorates.

The fluororesin layer 8 is a colorant. The fluororesin layer 8 is
The urethane primer layer 6 is hardened to a touch dry (a dry state in which the coating film does not reach the fingertips because the fingertips are touched), and then the urethane primer layer 6 is coated.

The fluororesin 8 is of a type that is cured by the reaction between the fluororesin and isocyanate, and can be colored in almost any color tone by adding a coloring pigment.

As the pigment component, white color (titanium white), green color (cyanine green), yellow color (Hansa yellow), blue color (calcined pigment of Co, Al, Cr oxide), orange color (Monbdate orange), Although a gray color (mixture of white titanium and a calcined pigment of Co, Al, Cr oxide) is used, it is appropriate that the proportion of the pigment component added to the paint is 1 to 50% by weight. .

If the addition ratio of the coloring pigment is too small, the coloring pigment will not be vividly colored, and if the addition ratio is too large, the strength of the coating layer will decrease, which is not preferable.

The coating thickness is 10 to 100μ, preferably about 20 to 60μ. If it is too thin, the black color of the lower urethane elastomer coating layer 3 cannot be shaded. Not relevant.

The coating method is air spray, airless spray, brush coating, or the like so as to obtain a uniform film thickness.

(Operation) The colored polyolefin resin-coated heavy corrosion-resistant steel material of the present invention is composed of layers as shown in FIG.

The inorganic primer layer 2, the organic primer layer 3, the adhesive layer 4, and the polyolefin resin layer 5 play a role of retaining adhesion to steel materials, impact resistance, water resistance, and insulation resistance.
The urethane primer layer 6 and the fluororesin layer 8 play a role of weather resistance (fading resistance).

The coating conditions for attaching the polyolefin resin layer 5 and the fluororesin layer 8 are important. Since the polar group does not exist on the adhesive surface of the polyolefin resin layer 5 in a normal state, it is necessary to introduce the polar group to the adhesive surface when the polyolefin resin layer 5 is coated thereon. As the method, there is a method of surface treatment of polyolefin by fire treatment method, corona discharge method, dichromate / sulfuric acid mixture treatment method, etc., but fire treatment method is preferable considering the shape of the steel material to be handled and the economicalness of the treatment method. Is.

In the fire treatment method, the surface of the polyolefin resin layer 5 is blown by a fire of a gas burner to raise the surface temperature of the polyolefin resin layer 5 to 60 to 90 ° C. to partially oxidize the surface of the polyolefin resin layer 5. , Activate. After that, the urethane primer layer 6 is coated with a film thickness of 5 to 20 μm, but a thin coating can stably cure the coating film in a short time.

After the coating film is dry to the touch or more, set the fluororesin layer 8 to 1
0-100 μ coating. The film thickness of the fluororesin layer 8 varies depending on the color tone. This is because while the color tone of the lower polyolefin resin layer 5 is shaded, the thickness of the film is made thinner and uniform on the one hand to obtain a more economical effect.

(Examples) The present invention will be described in more detail with reference to Examples.

Example-1 and Comparative Example-1 An outer diameter of 700 mm, a wall thickness of 8 mm, and a length of 11 mm were used to clean the outer surface of a steel pipe for piles by grit blasting, and then an inorganic primer (chromic acid type) and an organic type primer were used. (Epoxy type) is applied 30 to 50μ, adhesive (modified polyethylene) is applied 80 to 100μ, and polyolefin resin (low density polyethylene) is applied 2.5 to 2.8mm, and it is covered with propane burner for 5 minutes. The temperature of the surface of the polyolefin resin is raised to 70 to 80 ° C. by heating, and 5 to 10% of a urethane primer (50% by weight of urethane polymer and 50% by weight of toluene) is applied on it, and a fluororesin (fluororesin) is applied thereon. 60% by weight, pigment 26% by weight, isocyanate 14
Wt%) was applied in an amount of 30 to 40 μm.

The coating composition diagram thus obtained is shown in FIG. In the figure, 1 is a steel material, 2 is an inorganic primer layer, 3 is an organic primer layer, 4 is an adhesive layer, 5 is a polyurethane resin layer, 6
Is a urethane primer layer, and 8 is a fluororesin layer.

As a comparative material, an inorganic primer, an organic primer, an adhesive, a polyolefin resin, as in Examples,
The resin surface was fire-treated, a urethane primer was applied, and acrylic urethane was made to have a thickness of 20 to 40 μm. The coating construction diagram is shown in FIG. In the figure, 7 indicates an acrylic urethane layer.

The coating properties and coating film physical properties of the above Examples and Comparative Examples are shown in Table 1, coating conditions are shown in Table 2, and coating film performance is shown in Table 3.

Separately, a fluorocarbon resin of 30 to 60 μm was applied to a mild steel plate having a width of 70 mm, a length of 150 mm, and a wall thickness of 0.8 mm, and the deterioration of color fading over time (gloss retention rate and color difference) was tested in a weatherometer accelerated test. I checked up to 7,000 hours.

Also in the comparative example, acrylic urethane was applied in the same manner as in the example, and the test time was 6000 hours (because of the large deterioration of fading
(Discontinued after 6000 hours).

The results are summarized in Table 4 and the color difference in Table 5.

As shown in Table 3, the steel materials of the present invention have a coating film adhesion performance comparable to that of the comparative examples, and as shown in Tables 4 and 5, both gloss retention and color difference are significantly higher than those of the comparative examples. Is excellent.

As shown in the above Examples, the colored polyolefin resin-coated heavy corrosion-resistant steel material of the present invention is capable of maintaining the color tone of the outer surface coating for a long period of time while maintaining the adhesion performance between the layers.

(Effect of the invention) The colored polyolefin resin-coated heavy-corrosion protection steel material of the present invention has a long-term corrosion protection property by forming a polyolefin resin coating layer on the steel material surface and forming a fluororesin thereon, and the outer surface is It has a wide coloring range and has excellent long-term weather resistance (fading resistance). It is a steel structure that is exposed to the air and used in harmony with the surrounding environment for a long time. It can also maintain its integrity and aesthetics.

[Brief description of drawings]

FIG. 1 is an illustration of a heavy duty anticorrosion steel material coated with a colored polyolefin resin of the present invention, FIG. 2 is an illustration of a heavy duty anticorrosion steel material using a conventional polyolefin resin as an anticorrosion coating layer, and FIG. 3 is a comparison with an embodiment of the present invention. It is explanatory drawing of an example. 1 ... Steel, 2 ... Inorganic primer layer 3 ... Organic primer layer 4 ... Adhesive layer 5 ... Polyolefin resin layer 6 ... Urethane primer layer 7 ... Acrylic urethane layer 8 ... Fluorine resin layer

Claims (2)

[Claims] 1. A heavy anticorrosion steel material comprising a polyolefin resin as an anticorrosion coating layer, wherein the surface of the coating layer is subjected to flame treatment, and a urethane primer having an adhesive property with the polyolefin resin is preliminarily coated thereon in an amount of 5 to 20 μm, and then colored. A colored polyolefin resin-coated heavy anticorrosion steel material, characterized in that a fluororesin layer containing a pigment is provided in an amount of 10 to 100 μm. 2. The colored polyolefin resin-coated heavy corrosion-resistant steel material according to claim 1, wherein the surface coated with the polyolefin resin has been previously heat-treated at 60 to 90 ° C. by flame treatment.