JPH0531857A - Resin coated material excellent in weatherability - Google Patents

Abstract

PURPOSE:To obtain the subject resin coated material excellent in weatherability by providing a coating resin layer containing a deterioration inhibitor whose concn. becoming higher toward the interior thereof from the surface thereof. CONSTITUTION:A base material is generally a steel material but the material quality thereof is not limited to steel and other metal materials such as aluminum, a stone material, wood or ceramic can be used. The resin of a coating resin layer is not also limited and various resins used as coating resins heretofore such as polyolefins, for example, polyethylene or polypropylene, polystyrene, polyvinyl chloride or the like can be used. The thickness of the coating layer is appropriately selected corresponding to the objective degree of anticorrosion but set to 0.5-5mm, especially pref., about l-3mm in the case of heavy anticorrosion. As a deterioration inhibitor to be added, a known compound such as a phenol derivative, an aromatic amine derivative, a sulfur compound or a phosphorus compound is designated. The mol.wt. of the deterioration inhibitor is pref. 100-2000, especially pref. 200-1000.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a resin coating material having excellent weather resistance (eg, resin coating) having a coating resin layer in which a deterioration preventing agent such as an antioxidant or an ultraviolet absorber is added in high concentration from the surface. Steel material).

[0002]

2. Description of the Related Art Steel materials used outdoors for a long time may be exposed to a severe corrosive environment. For example, steel sheet piles and steel pipe sheet piles are continuously driven into the ground to form protective fences, mainly for the purpose of reveting rivers, coasts, harbors, etc. Is used for. Ordinary steel pipes are also often used as gas pipes and water pipes. These steel materials are exposed to river water, drainage water, rainwater, seawater, and other water, the atmosphere, and sunlight in an outdoor natural environment, and also come into direct contact with earth and sand, mud, rubble, etc., causing significant corrosion. It is easy to occur, and effective anticorrosion measures have been desired. In recent years, as a countermeasure against this, heavy-corrosion-coated steel materials having excellent corrosion resistance by coating a resin with a thick film (1 to 3 mm) are being used.

However, the resin easily deteriorates under the influence of ultraviolet rays contained in sunlight, and therefore, when used outdoors as in the above-mentioned applications, carbon black is added in an amount of 1 to 3% to provide weather resistance. It was generally improved, and the color tone was limited to black. Therefore, in a place where the living environment and natural environment should be kept comfortable and beautiful, it is necessary to color the steel sheet pile and the steel pipe sheet pile so as to be compatible with the living environment and natural environment. Deterioration measures are taken.

As measures against ultraviolet deterioration, substances such as coloring pigments and benzotriazole compounds that absorb ultraviolet light and convert it into low energy (ultraviolet absorber), and HA
Antioxidizing agents such as LS, hindered phenol compounds, sulfur compounds, and phosphorus compounds have been added to resins either individually or in combination. In this specification, the ultraviolet absorber and the antioxidant are collectively referred to as a deterioration inhibitor. As a method of adding the deterioration inhibitor, a method of adding an ultraviolet absorber only to the surface (Japanese Patent Laid-Open No. Sho 61-61)
No. 202836) and a method of adding an ultraviolet absorber and an antioxidant to the whole resin (Japanese Patent Laid-Open No. 63-60712).

[0005]

However, these deterioration inhibitors are expensive and cost several times or more as compared with the base resin, and the addition thereof causes a rise in product cost. In particular, the outer surface coating of outdoor pipes such as water and gas, steel pipe piles,
Heavy anticorrosion coatings such as steel sheet piles and steel pipe sheet piles require the addition of a large amount of antioxidants and / or ultraviolet absorbers, which is a cause of markedly impairing the economical efficiency of products.

An object of the present invention is to provide a resin-coated steel material which imparts long-term weather resistance to ultraviolet rays to steel materials such as steel sheet piles, steel pipe sheet piles, steel pipe piles and steel pipes for outdoor piping without impairing economic efficiency. To do.

[0007]

[Means for Solving the Problems] Incidentally, regarding the deterioration of the resin coated on the surface of the steel material due to ultraviolet rays, the deterioration itself has been regarded as a problem from the past, but the behavior of the deterioration preventing agent in the resin has been reported so much. It has not been. The present inventors have focused on the diffusion behavior of additives such as deterioration inhibitors in resins. As a result, the consumption per unit time of the deterioration inhibitor from the surface of the resin coated on the steel material,
It is the sum of the constant consumption that is consumed by being irradiated with sunlight within that time and the varying consumption that depends on the surface concentration (surface layer thickness 0.01 mm).
It was found that the deterioration inhibitor is consumed by the mechanism that the deterioration inhibitor diffuses from the inside to the surface in the resin.

Therefore, in order to improve the life of the resin coated on the surface of the steel material with respect to ultraviolet rays, the total amount of the resin added should be smaller than the conventional method in which the ultraviolet absorber or the antioxidant is added to the entire coating resin or only the surface. Similarly, by lowering the concentration of the deterioration inhibitor added to the outermost surface layer, the consumption of the additive that depends on the surface concentration is suppressed, and if the internal deterioration inhibitor diffuses over time, It was found that the inhibitor can function for a longer period of time and the life of the coating resin can be extended. According to this means, not only the deterioration of the entire coating resin by ultraviolet rays is prevented, but also in order to achieve a life equivalent to that of the conventional one, the amount of the expensive deterioration inhibitor added should be greatly reduced from the conventional amount. Therefore, it is possible to significantly improve the economical efficiency of the heavy anticorrosion coated steel material.

The present invention has been made on the basis of the above findings and provides a resin coating material having excellent weather resistance, which is characterized in that it is provided with a coating resin layer containing a deterioration inhibitor inside the surface at a high concentration. And

[0010]

The structure of the present invention will be described in detail below together with its operation. The base material to which the resin coating is applied in the present invention is
Generally, the material is steel, but the material is not limited to steel, and other metal materials such as aluminum, stone, wood, and ceramic are also possible. The steel material, which is a typical material, will be described below.

The shape of the steel material is not particularly limited, and may be a tubular material such as a steel pipe or a steel pipe pile, or a plate material such as a steel sheet pile or a steel plate,
Further, it may be a steel bar or a profiled material. Also, steel materials are plated or chemical conversion treated (chromate treatment, zinc phosphate treatment)
An appropriate base treatment such as the above may be applied.

Further, in order to improve the adhesiveness with the coating resin layer, a coating pretreatment such as coating a suitable primer on the surface of the steel material, baking and drying it before coating with the resin is carried out, if necessary, as in the conventional case. Can be implemented.

The resin type of the coating resin layer is not particularly limited, and polyolefins such as polyethylene and polypropylene,
Various resins conventionally used for coating such as polystyrene and polyvinyl chloride can be used. The thickness of the coating resin layer is appropriately selected according to the desired degree of anticorrosion. In case of heavy corrosion protection, 0.5-5 mm, especially 1-3
It is preferably about mm. When coating a resin having relatively low adhesiveness such as polyolefin, a resin layer for imparting adhesiveness (eg, maleic anhydride-modified polyethylene) is commonly used to enhance the adhesiveness with steel materials. Layer) may be present at the interface between the steel material and the resin.

Deterioration inhibitors added to the coating resin layer include phenol derivatives, aromatic amine derivatives, piperidine derivatives, sulfur compounds, phosphorus compounds, organometallic compounds, hydrazine compounds, benzotriazole compounds, benzophenone compounds. Compounds, benzoate compounds,
Examples of compounds that have hitherto been known as ultraviolet absorbers or antioxidants, such as cyanoacrylate compounds, are exemplified. As a prescription for imparting weather resistance, many of these additives are used in combination, but only one may be added.

The deterioration inhibitor used has a molecular weight of 100 to 2000.
Those having a molecular weight of 200 to 1000 are particularly preferable. According to the research conducted by the present inventors, with an anti-degradation agent having a molecular weight of less than 100, the diffusion rate in the resin is high, and diffusion occurs rapidly from the inside to the surface, and the anti-deterioration agent itself is deactivated by ultraviolet rays on the resin surface. Also, consumption due to elution is accelerated, and deterioration of the resin layer is accelerated. On the other hand, an anti-degradation agent with a molecular weight of more than 2000 has a slow diffusion speed in the resin, and the internal anti-degradation agent does not sufficiently diffuse on the resin surface, and cannot keep up with the generation rate of active species in the deterioration reaction by ultraviolet rays. , The surface is easy to deteriorate. On the other hand, the molecular weight is 100 to 2000, especially 200 to 10
The deterioration inhibitor within the range of 00 diffuses from the inside to the surface at an appropriate speed and continues to be supplied to the surface, so that the action can be effectively exerted for a long period of time.

The total amount of deterioration inhibitor added to the coating resin layer is
As will be exemplified later in Examples, the amount may be the same as the conventional amount or a small amount. When the total addition amount is similar to the conventional one, the weather resistance is improved and the resin life is extended as compared with the conventional uniform addition or addition only to the surface. Also, if the purpose is to achieve a resin life comparable to the conventional one, the total amount of expensive deterioration inhibitor can be considerably reduced, so that the manufacturing cost of the resin-coated steel material is reduced and the economic effect is improved. Is demonstrated.

If desired, one or more known additives such as color pigments, extender pigments, rust preventive pigments, dispersants and softeners may be added to the coating resin layer in addition to the deterioration inhibitor. Good. The resin coating material of the present invention can be produced by various methods such as A to E illustrated below, regardless of the shape.

A: Method based on melt extrusion method, B: Method based on electrostatic powder coating method, C: Method based on fluidized dipping method, D: Method based on thermal spraying method, E : A method based on a sheet laminating method.

With the exception of the method E, in any method, after the surface is cleaned by pickling and / or blasting, etc., the steel material surface preheated to about 120 to 360 ° C. by an appropriate heating means such as induction heating, A resin containing a large amount of the above-described deterioration inhibitor is coated by any of the methods A to D to form an inner coating layer. While the coating resin is in the molten state at the melting point or higher, in order to form the surface coating layer, the resin containing a small amount of the deterioration inhibitor is also coated by any of the above methods A to D, and the coating is performed first. A resin-coated steel material having a coating resin layer containing a high-concentration deterioration inhibitor on the surface thereof is obtained by integrating with an internal coating layer containing a high-concentration deterioration inhibitor. In some cases, the inner coating layer and / or the surface coating layer may be two or more layers, or the concentration of the deterioration inhibitor may be gradually increased from the outermost surface layer toward the inside.

The same kind of resin, kind of deterioration inhibitor and coating method used for forming the surface coating layer and the internal coating layer facilitates the production, but may be changed if desired. Generally, the thickness of the surface coating layer having a low concentration of the deterioration inhibitor is preferably about 20 to 90% of the total thickness of the resin layer.

In the methods A and B described above, after the surface is cleaned, a sheet of molten resin is adhered to the preheated steel material, or resin powder is sprayed on the steel material to make an internal coating in which a large amount of a deterioration inhibitor is added. After forming the layer, a resin having a small addition amount of the deterioration inhibitor when the coating layer is in the molten state at the melting point or higher may be coated thereon by the same method. In the methods C and D, the cleaned and preheated steel material is immersed in a tank in which a resin powder containing a large amount of deterioration inhibitor is flowing, or the powder is electrostatically sprayed onto the surface of the steel material. After coating the resin by spraying and spraying with, when the first resin coating is in the molten state at the melting point or higher, the resin with a small addition amount of the deterioration inhibitor is coated in the same manner to obtain the target thickness. It can be carried out by finishing.

In the laminating method of E, the resin which has been formed into a sheet shape in advance is attached to the surface of the steel material which has been cleaned and preheated. In the case of the present invention, the resin sheet is formed. By using the double extrusion method or the extrusion lamination method, a two-layer resin sheet having a surface coating layer with a small amount of the deterioration inhibitor added on one side is formed. It may be attached to the surface of the steel material so that many inner coating layers are on the inside. Alternatively, an inner coating layer sheet with a large amount of deterioration inhibitor and a surface coating layer sheet with a small amount of deterioration inhibitor are prepared separately, and these two resin sheets are used as the inner coating layer sheet inside. The resin-coated steel material of the present invention can also be produced by simultaneously attaching the steel material surface to the steel material.

[0023]

EXAMPLES Next, the present invention will be described in detail with reference to Examples.

Steel sheet pile (Sumitomo Metal Industries Co., Ltd .; SKSP-I
Adjust the surface of the (I type) surface by shot blasting (S
a. 2.5 or more), followed by chromate treatment (Kansai Paint Co., Ltd .; Cosmer 100) so that the amount of deposited chromium was 200 g / mm ² . Epoxy primer (Nippon Paint Co., Ltd .; No. 66 primer) was applied to this steel sheet pile to a dry film thickness of 30 μm, and the steel material was heated to 190 ° C. by an induction heating device. Baking and preheating of steel materials were performed.

On the other hand, polyethylene (SHOREX S4002 EX, Showa Denko KK) was used as the resin, and an antioxidant and an ultraviolet absorber were blended in each resin layer as follows. In addition, in Example 1 and Comparative Examples 1 and 2, the total addition amounts of the antioxidant and the ultraviolet absorber in the coating resin layer were the same. The antioxidants and UV absorbers used were as follows. Among them, A is an ultraviolet absorber,
B to E are antioxidants. A: 2- (3-t-butyl-5-methyl-hydroxyphenyl) -5-chlorobenzotriazole; B: bis (2,2,6,6-tetramethyl-4-piperidine sebacate); C: 3 , 9-bis [2- {3- (3-t-butyl-4-
Hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethylethyl] -2,4,8,10-
Tetraoxaspiro [5,5] undecane; D: tris (2,4-di-t-butylphenyl) phosphite; E: 4,4'-thiobis (3-methyl-6-t-butylphenol).

Example 1 : 0.1 wt% of the above-mentioned antioxidant was applied to a portion having a thickness of 2.0 mm from the coating surface of the outermost surface layer.
(B: 0.025 wt% + C: 0.025 wt% + D: 0.025 wt% +
E: 0.025wt%), 2.0 to 2.5 from the outermost surface coating surface.
1.6 wt% (B: 0.4
wt% + C: 0.4 wt% + D: 0.4 wt% + E: 0.4 wt%) was added.

Example 2 : 0.1 wt% of the above-mentioned antioxidant was applied to a portion having a thickness of 2.0 mm from the coating surface of the outermost surface layer.
(B: 0.025 wt% + C: 0.025 wt% + D: 0.025 wt% +
E: 0.025wt%), 2.0 to 2.5 from the outermost surface coating surface.
1.2 wt% (B: 0.3
wt% + C: 0.3 wt% + D: 0.3 wt% + E: 0.3 wt%).

Comparative Example 1 : 0.4% of antioxidant was added to the coating resin layer.
wt% (B: 0.1 wt% + C: 0.1 wt% + D: 0.1 wt% +
E: 0.1 wt%) was added uniformly.

Comparative Example 2 : Thickness from outermost surface layer is 0.5 mm
1.6 wt% (B: 0.4 wt% +
C: 0.4 wt% + D: 0.4 wt% + E: 0.4 wt%), and 0.1 wt% (B: 0.025%) of the above-mentioned antioxidant to the remaining 0.5 to 2.5 mm thick portion from the outermost surface layer. wt% +
C: 0.025 wt% + D: 0.025 wt% + E: 0.025 wt%).

The ultraviolet absorber A is uniformly applied to all layers.
It was added at a concentration of 0.1 wt%. The above two layers (comparative example 1 is 1
Layer) and the adhesive layer made of maleic anhydride-modified polyethylene (manufactured by Mitsui Petrochemical Industry Co., Ltd .; Admer), which is the innermost layer, are coextruded in three layers to obtain an antioxidant content. A multi-layer polyethylene sheet comprising two layers (low surface layer concentration, intermediate layer high concentration) and an innermost adhesive layer was prepared.

After heating this multilayer polyethylene sheet to 200 ° C. with an infrared heater, a layer with a small antioxidant content of the sheet becomes the surface (the adhesive layer is the inner surface) on the convex portion of the preheated steel sheet pile. , The modified polyethylene adhesive layer was fused and adhered to the steel sheet pile by a pressing roll to obtain a heavy corrosion-resistant steel sheet pile covered with a polyethylene resin sheet.

From this polyethylene resin coated steel sheet pile 150
Using a test piece obtained by cutting out a steel plate of 70 mm, the time until cracking of the coating layer by the WOM accelerated test was investigated as weather resistance to ultraviolet rays. The results are shown in Table 1 below.

[0033]

[Table 1]

As can be seen from the results shown in Table 1, in Example 1 according to the present invention, although the total amount of addition of the antioxidant and the ultraviolet absorber was the same as in Comparative Examples 1 and 2, comparison was made. The weather resistance is better than that of the example. From this, when the concentration of the antioxidant on the outermost surface is high, the antioxidant is meaninglessly consumed, which does not effectively contribute to long-term weather resistance.
It turns out to be uneconomical. In Example 2, even though the amount of the antioxidant added was smaller than that of Comparative Examples 1 and 2, the weather resistance was better than that of the Comparative Example. According to the present invention, the addition of a small amount of the antioxidant results in a long resin life. It can be seen that this can be achieved.

[0035]

As described above, the resin-coated steel material of the present invention is completely opposite to the conventional idea, in which the deterioration preventing agent (antioxidant and ultraviolet absorber) on the surface of the resin layer is reduced, By adding a large amount of the deterioration preventing agent, useless consumption of the deterioration preventing agent can be prevented. As a result, the effect of improving the weather resistance due to the addition of the deterioration inhibitor to the resin can be maintained for a longer period of time with the same addition amount as in the conventional case, and the resin life can be extended. Alternatively, it is possible to obtain a resin life equivalent to that of the conventional resin by adding a smaller amount of the deterioration preventing agent than before, and to obtain a resin-coated steel material having excellent weather resistance by reducing the amount of addition of the expensive deterioration preventing agent. , It has a great economic effect.

Claims (1)

Claim: What is claimed is: 1. A resin coating material having excellent weather resistance, comprising a coating resin layer containing a deterioration inhibitor in a higher concentration than the surface thereof.