JPH0373340A - Polyolefin clad steel material excellent in resistance to hot salt water - Google Patents

Abstract

PURPOSE:To improve the high temperature adhesion, resistance to hot salt water and resistance to cathode peeling at high temperature of the sheet material concerned by a method wherein chromating agent layer, epoxy primary layer, the essential ingredients of which consist of three specified ingredients, modified polyolefin resin layer and polyolefin resin layer are laminated in the order named onto the surface of copper material. CONSTITUTION:Chromating agent layer 2, epoxy primer layer 3, the essential ingredient of which consists of ingredients (a), (b) and (c) mentioned below, modified polyolefin resin layer 4 and polyolefin resin layer 5 are laminated in the order named onto the surface of copper material 1. The (a) is single phenolic novolak type glycidyl ether or epoxy resin, which is prepared by mixing single or two or more of diglycidyl ether of bisphenol A, A or F with said phenolic novolak type glycidyl ether. The (b) is modified polyamine, which is prepared by condensing m-xylenediamine and epichlorohydrin. The (c) is inorganic pigment.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a polyolefin-coated steel material, and more specifically to a polyolefin-coated steel material that has excellent long-term hot brine resistance.

(Prior Art) In order to prevent corrosion of steel materials such as steel and steel pipes, the surfaces of steel materials are increasingly coated with polyolefin resins such as polyethylene and polypropylene, which have excellent chemical stability. However, the environment in which these polyolefin-coated steel materials are used is such that, for example, in buried pipes used for heating an entire region, the pipe surface temperature is high, and especially in buried areas where the groundwater level is high, the entire pipe is below the groundwater level containing seawater. The situation is becoming extremely harsh, with polyolefin-coated steel materials being immersed in hot salt water. Generally, polyolefin resins are non-polar due to their chemical structure, so they cannot be directly bonded to highly polar surfaces such as steel. Therefore, a method has been adopted in which a polyolefin resin is coated with a modified polyolefin resin modified with an unsaturated carboxylic acid or its acid anhydride. However, the adhesive strength between the polyolefin and the steel material decreases as the temperature of the use environment, the amount of moisture in the use environment, or the salt concentration increases. When the above-mentioned coated steel material is used in an extremely harsh environment such as a hot salt water environment, it is particularly important to maintain the adhesive strength in hot salt water, that is, to improve the heat salt water resistance. In response to these problems, the present inventors have developed a coating structure that uses a combination of chromate treatment and epoxy primer treatment for steel materials, and in particular, for the composition of the epoxy primer, a specific epoxy resin and m-xylene sia are mainly used. A method using a modified aliphatic polyamine obtained by reacting and adding an alkyl glycidyl ether to a condensate of chlorohydrin and epichlorohydrin, and an inorganic pigment as the main components (Japanese Patent Application Laid-open No. 1-150540);
Also, JP-A-56-143223, JP-A-59-222
No. 275 and Japanese Unexamined Patent Publication No. 60-245544 have proposed a method using an epoxy primer made by mixing a specific epoxy resin with an inorganic pigment and an amine curing agent and curing the mixture by reaction. .

(Problems to be Solved by the Invention) These surface treatment methods are effective in improving heat salt water resistance (immersion time within 8000 hours) in hot salt water exceeding 90°C or in improving high-temperature cathode removability. There is. However, JP-A No. 1-150540, JP-A No. 56-14
No. 3223, JP-A-59-222275, JP-A-60
Even when romate treatment and epoxy primer treatment are used together as shown in No. 245544, the adhesive strength between the coating and the steel material is maintained when immersed in hot salt water over 90°C for a long period of 8000 hours or more. is difficult. Therefore, it is desired to develop an excellent polyolefin-coated steel material that can maintain adhesive strength even when immersed in hot brine at a temperature of over 90° C. for over 8,000 hours.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present inventors have made an effort to solve the problems described above.
150540, JP-A-56-143223, JP-A-59-222275, and JP-A-60-245544, the coating structure uses both chromate treatment and epoxy primer treatment. 1-15
As a result of improving the composition of the epoxy primer of Publication No. 0540, we found that phenol novolac-type glycidyl ether alone, or the phenol-volac type glycidyl ether plus bisphenol A, AD, or
The above-mentioned problems can be solved by using an epoxy primer composed of an epoxy resin consisting of diglycidyl ether F alone or a mixture of two or more, a modified polyurethane made by condensing m-xylene diamine and epichlorohydrin, and an inorganic pigment. The inventors have discovered that the problem can be solved, leading to the present invention.

That is, the gist of the present invention is a kwamate treatment agent layer on the surface of a steel material, as described in (a) and (b) below.

A polyolefin-coated steel material with excellent hot brine properties for a long period of time or more, characterized by sequentially laminating an epoxy primer layer, a modified polyolefin resin layer, and a polyolefin resin layer containing the three components (C) as essential components.

(a) An epoxy resin consisting of a phenol novolac-type glycidyl ether alone, or a mixture of the phenol novolac-type glycidyl ether and diglycidyl ether of bisphenol A, AD, or F, alone or in combination.

(b) A modified polyamine obtained by condensing m-xylene diamine and epichlorohydrin.

(C) Inorganic pigment.

That is, as shown in FIG. 1 according to the present invention 1, a chromate m filler layer 2 is formed on the surface of a steel material 1, and the above-mentioned (a) and (b)
The present invention relates to a polyolefin-coated steel material having excellent hot brine resistance, characterized in that an epoxy primer layer 3, a modified polyolefin resin layer 4, and a polyolefin resin layer 5, all of which have component (c) as an essential component, are sequentially laminated.

Hereinafter, the present invention will be explained in detail.

First, the steel materials used in the present invention include steel pipes, sections, steel plates, steel bars, and steel molded products and structures made of alloy steels such as carbon steel and stainless steel, and are used outdoors, underground, above ground, etc. This is a general term for things that are widely used on the ocean floor.

Next, the coating structure in the present invention will be explained based on FIG. 1.

In the present invention, the key points are the steel material 1 and the modified polyolefin resin F! The main point is to have a structure in which a chromate treatment agent layer and an epoxy primer layer are interposed between the first
Between the steel material 1 and the chromate treatment agent layer 2 in the figure, a plating layer of zinc, aluminum, chromium, nickel, etc., zinc-iron,
An alloy plating layer such as zinc-nickel or zinc-nickel-cobalt, or a dispersion plating layer in which inorganic fine particles such as silica alumina, silica alumina, titanium oxide, silicon carbide, boron nitride, etc. are dispersed in the plating layer or alloy plating layer. Even if the polyolefin resin layer exists, it does not impair the gist of the present invention in any way, and if the polyolefin resin layer has a two-layer structure, the upper layer contains a fiber reinforced material, fine powder, or flaky reinforcing material, and the lower layer contains a polyolefin resin containing a fiber reinforced material, a fine powder, or a scale-like reinforcing material. It may also be provided with a polyolefin resin layer.

Next, the epoxy primer used for forming the epoxy primer layer of the present invention is a mixture (d) in which an epoxy resin as a component (a) and an inorganic pigment as a component (c) are mixed in advance. ) A modified aromatic polyamine obtained by condensing component m-xylene diamine and epichlorohydrin, such that the ratio of the epoxy equivalent of (d) to the active hydrogen equivalent of (b) is in the range of 0.6 equivalent to 2.0 equivalent. It is a mixture mixed like this.

The epoxy resin which is the above component (a) is phenol novolac type glycidyl ether alone, or bisphenol A in addition to the phenol novolac type glycidyl ether.

Single or two diglycidyl ethers of AD or F
It is an epoxy resin mixed with f1 or more.

Phenol novolak type glycidyl ether has the following molecular structure, and from the viewpoint of heat and salt water resistance, the phenol novolac type glycidyl ether has a molecular weight of 312 to 312.
6792 (0≦n≦40), and the epoxy equivalent is in the range of 155 to 230. Applicable commercial products include Epicoat 152, Ebiko-154, manufactured by Yuka Shell Epoxy Co., Ltd., and Evoto-YDPN-638゜"I'DPN-601, YD, manufactured by Tobu Kasei Co., Ltd.
PN-602, DEN431 manufactured by Dow Chemical Japan.
DEN438. DEN439, DEN485, manufactured by Ciba Geigy (7) EPN1138. EPN1139
．． XPY307 (D grades are included.

The diglycidyl ether of bisphenol A has the molecular structure of Each grade of Epicoat 827 and Epicoat 834, EvoMik R139 and EpoMik R140 manufactured by Mitsui Petrochemical Industries, Ltd.
, Epomic R140P, Epomic R140C, and Evomic R144 grades, and Asahi Denka's Adekal Resin EP 4100. ADEKA RIN EP 4100E
, Adekal Resin EP 4200. ADEKA RESIN EP
Each grade of 4300, Evotote Y manufactured by Tobu Kasei Co., Ltd.
D115. Epotote Y D 121. Epotote Y D 122. Epotote Y D 128. Each grade of Evotote YD H4, DER317, DER330, DER331, DER3 manufactured by Dow Chemical Japan Co., Ltd.
Examples include grades of 33° DER383 and DER387.

In addition, the diglycidyl ether of bisphenol AD has the following molecular structure and preferably has an epoxy equivalent in the range of 170 to 185 from the viewpoint of heat and brine resistance. Epomic R7
10, various grades of Evomic R710H, etc.

Furthermore, bisphenol F type diglycidyl ether has the following molecular structure, and from the viewpoint of heat salt water resistance, it is desirable to have an epoxy equivalent in the range of 170 to 185. Epicoat 8 made by
07 is mentioned.

the aforementioned phenol novolac-type glycidyl ether;
Alternatively, by using an epoxy primer in which a molar pigment is added to a mixture of the phenol novolac type glycidyl ether and the above-mentioned epoxy resin, the long-term hot brine properties are significantly improved. Here, the phenol novolak type glycidyl ether has a high viscosity at room temperature,
Or if it is in a solid state, for example, Epicote 154
When using a diluent, the viscosity is lowered by diluting it with a solvent, with diglycidyl ether of bisphenol F, or with other conventionally known reactive diluents. However, this does not impede the gist of the present invention in the slightest.

If a polyfunctional epoxy resin such as tetraglycidyl metaxylene diamine is used instead of the above-mentioned phenol novolac type glycidyl ether, it is not desirable because the long-term heat salt water resistance will rather deteriorate. Regarding the blending of the glycidyl ether and the above epoxy resin, the above epoxy resin 100
It is preferable to mix the phenol novolac type glycidyl ether in an amount of 1 to 100 parts by weight based on the epoxy resin. If the mixing amount is less than 1 part by weight, the above-mentioned effect will hardly be obtained.Furthermore, if the molecular weight of the phenol novolac type glycidyl ether is 6,792 or more, it will cause significant difficulty in handling, which is not desirable.

The modified polyamine, which is a condensation of m-xylene diamine and epichlorohydrin, which is the component (b), has the following molecular structure, and from the viewpoint of hot brine properties, the molecular weight is 32.
It is desirable that the polymerization degree is 8 or more (degree of polymerization n≧1), and applicable commercial products include Gascamin G32 manufactured by Mitsubishi Gas Chemical Co., Ltd.
8. G32BS (polymerization degree nwo from the constituent components of G328
). however,
From the viewpoint of handling, as the molecular weight of the modified polyamine increases, the viscosity also increases, so a method of diluting it with a solvent,
The use of other conventionally known low-viscosity curing agents or methods of diluting with diluents does not pose any hindrance to the present invention. Regarding the mixing of m-xylene diamine and a modified polyamine obtained by condensing epichlorohydrin, the mixing ratio between the epoxy equivalent and the active hydrogen equivalent of the amine curing agent is preferably in the range of 0.6 to 2.0. When the ratio is less than 0.6, long-term heat salt water resistance is significantly reduced. In addition, if the mixing ratio is greater than 2.0, the amount of unreacted amine curing agent remaining in the formed coating film will significantly increase, resulting in a high water absorption rate and long-term immersion in heat salt water. The coating film swells during the process, and its hot brine properties are significantly reduced.

The inorganic pigment that is component (C) is titanium oxide (for example,
K R380, K R480, etc. manufactured by Titan Kogyo Co., Ltd.),
Silica (for example, Aerosil 20 manufactured by Nippon Aerosil Co., Ltd.)
0. Aerosil 300. Micron 5R70,5
RC18, etc.), silica/alumina (Japan Aerosil <7) COH84, MOX80, etc.), talc (Talcan Powder P KP, manufactured by Hayashi Kasei Co., Ltd.).

micron white s 5ooo, etc.), mica-like iron oxide (MIO-KS, manufactured by Kikuchi Shiki Kogyo Co., Ltd.), muscovite (Librite RD100, Librite RD200, manufactured by Ito Ceramic Materials Co., Ltd.)
Ribrite RD300, etc.), Sujirite Mica (Kuraray 150-Kl, 200-, 1.325-K1, etc.),
Aluminum tripolyphosphate (manufactured by Teikoku Kako Co., Ltd., White 105, etc.), chromium oxide (Cr
20. ), chromic phosphate (CrPO4), zinc phosphate (Zns (PO4) 2 , 4 HJ), magnesium phosphate (MgHPO4.3) 120), aluminum phosphate (ARPO4), Hewei iron oxide yellow (titanium Synthetic iron oxide red (Mabico Red, etc. manufactured by Kogyo Co., Ltd.), barium sulfate (BaSOJ, etc.), zirconium phosphate (ZSP100, manufactured by Kigenso Kagaku Kogyo Co., Ltd.)
．． 1sP110. Cerawhite, etc.), carbon black (Mitsubishi Kasei #3Q50. #3150. #3250゜#3750.#3970), zirconium silicate (Micropax, zirconyl, manufactured by Hakusui Chemical Co., Ltd., MZ100OB manufactured by Ki Genso Kagaku Kogyo Co., Ltd.) etc.), zirconium oxide (BR-90G manufactured by Kigenso Kagaku Kogyo Co., Ltd.), kaolin clay (5ATINTONE-W manufactured by Hayashi Kasei Co., Ltd.), etc.
species or a mixture of two or more species.

Furthermore, in order to improve the wettability with the epoxy resin, the surface of the pigment described above may be subjected to chemical treatment such as aluminum-silica treatment, silane coupling treatment, phosphoric acid treatment, etc.

The amount of the above inorganic pigment added is preferably 1 to 45 parts by weight per 100 parts by weight of the epoxy resin, which is the component (a), from the viewpoint of heat salt water resistance. In order to adjust the curing time of the epoxy primer, for example, Curesol 2 M Z and Cure7sol 2 E 4 M Z manufactured by Shikoku Kasei Co., Ltd. are used as curing accelerators.
, Kis7zo/l/CIIZ, Ky7zool c17Z
There is no problem even if a small amount of imidazole curing accelerator such as Curazole 2PZ, Curazole 2P4MZ, etc. is added.

Next, the chromate treatment agent used for forming the chromate treatment agent layer of the present invention will be explained.

The chromate treatment agent used in the present invention is an organic reducing agent such as corn starch that reduces the
A silica-based chromate treatment agent made by adding fine silica powder to an aqueous solution of partially reduced chromic acid (CrO2) so that the weight ratio of valent chromium is in the range of 0.35 to 0.65, partially saponified polyvinyl acetate, and starch. Phosphoric acid is partially reduced using a polymeric organic reducing agent such as dextrin partially hydrolyzed with a hydrolase such as amyloglucosidase so that the weight ratio of hexavalent chromium to total chromium is in the range of 0.35 to 0.65. Silica, silica, and chromic acid in a mixed aqueous solution
A cynic acid-silica-based chromate treatment agent to which silica-based fine powder such as Alyosu is added can be used. From the viewpoint of high-temperature #polar peeling, the phosphoric acid-silica-based chromate treatment agent is desirable.

Next, the polyolefin resin and modified polyolefin resin used for forming the polyolefin resin layer and modified polyolefin resin layer of the present invention will be explained.

The polyolefin resins used in the present invention include conventionally known polyolefins such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, straight-line low-density polyethylene, polypropylene, and nylon, as well as ethylene-propylene block or random copolymers, and polyamides. - Conventionally known polyolefin copolymers such as propylene block or random copolymers.

In addition, modified polyolefin resin is one obtained by modifying the above-mentioned polyolefin resin with an unsaturated carboxylic acid such as maleic acid, acrylic acid, or methacrylic acid or its acid anhydride, or one obtained by appropriately diluting the modified product with polyolefin resin. These are conventionally known modified polyolefins.

Next, a method for manufacturing a polyolefin-coated steel material based on the present invention will be described using a polyolefin-coated steel pipe as an example.

The polyolefin-covered NtI4 tube can be obtained, for example, by the manufacturing method shown in FIG. That is, a chromate treatment agent is applied to the surface of the steel pipe 1 from which scale and the like have been removed by a chromate treatment agent application device 6, and baked by a heating device 7.Next, an epoxy primer 3 is applied to the surface by an epoxy primer application device 8. Apply and
The post-heating device 9 heats and hardens. Next, a modified polyolefin resin 4 is applied to the surface by a modified polyolefin resin coating device 10, and a polyolefin resin 5 is extruded and coated by a T-die 11, and then cooled by a cooling device 12 to obtain a polyolefin-coated steel pipe. In the case of the manufacturing method described above, a chromate treatment agent is applied to the surface of the steel pipe 1, and after baking with a heating device 9, the steel pipe is coated with a modified polyolefin resin coating device 1.
It is sufficient that the epoxy primer layer is formed on the surface of the steel pipe and sufficiently hardened before the temperature reaches 0, and the epoxy primer layer is formed on the surface of the steel pipe.
The method for applying the above-mentioned epoxy primer can be appropriately selected from conventionally known methods such as spray coating using a spray coating machine, roll coating, ironing, brush coating, and flow coating.

The method for heating the steel pipe by the post-heating device 9 can be appropriately selected from conventionally known methods such as high-frequency induction heating, far-infrared heating, and gas heating. In addition, the wall thickness of the steel pipe is thick, and the heating capacity of the heating device 7 is large,
If the epoxy primer layer is sufficiently cured, heating by the post-heating device 9 may be omitted.

Furthermore, in FIG. 2, modified polyolefin resin coating device 1
0 uses a method of electrostatically coating polyolefin resin powder, but there are also methods of extrusion coating the modified polyolefin resin using a T-die or round die, and methods of coating the modified polyolefin resin and polyolefin resin in two layers integrally using a T-die or a round die. Conventionally known methods such as extrusion coating from a round die can be employed.

(Function) A partial cross section of the polyolefin-coated steel material according to the present invention obtained as described above is as shown in FIG. 2 is a chromate treatment agent layer, 3 is an epoxy primer that requires the following three components: (a) Phenol novolac type glycidyl ether alone, or bisphenol A in the phenol novolac type glycidyl ether. , AD, or
An epoxy resin containing F diglycidyl ether alone or in combination with 2f1 or more.

(b) A modified polyamine obtained by condensing m-xylene diamine and epichlorohydrin.

(C) Inorganic pigment.

4 indicates a modified polyolefin resin layer, and 5 indicates a polyolefin resin layer.

In addition, 2 in the figure is 250 to 120 as the total chromium weight.
Good results can be obtained with a coating weight of 0.01 g/12, a thickness of 5 to 350 μm for 3, and a thickness of 1.0 to 10 mm for 5.

Hereinafter, the present invention will be specifically explained with reference to Examples.

(Example) First, in order to specifically explain the present invention, Examples 1 to 41 of the primer formulation according to the present invention, and as a comparative example, Comparative Example 1 of the primer formulation corresponding to JP-A-56-143223. ~4, JP-A-59-222275, JP-A-80
Comparative Examples 5 to 31 of primer formulations corresponding to No.-245544, and Comparative Example 32 of primer formulations other than the above
Table 1 shows Comparative Examples 41 to 47 of the formulations of brimer corresponding to JP-A No. 1-150540.

The epoxy resins listed in Table 1 are listed in Table 2, the curing agents are listed in Table 3, and the inorganic pigments are listed in Table 4. Also, the amounts of curing agent and inorganic pigment listed in Table 1 are per 100 parts by weight of epoxy resin! (parts by weight), and the amount of solvent added is the amount (% by weight) per 100 parts by weight of the brimer.Furthermore, the following chromate treatment agents I and II were used for surface treatment of steel materials.

(2) A silica-based fuchromate treatment agent Fusuma-9100 II manufactured by Kansai Paint Co., Ltd. Phosphoric acid-silica-based chromate treatment IJ prepared by the following method First, the following solutions (1), (2) and (2) were prepared.

■ Mixed aqueous solution of phosphoric acid and chromic anhydride in distilled water 247.
49.2 g of phosphoric acid and 78.8 g of chromic anhydride were dissolved in 6 g.

(2) 5% by weight partially saponified polyvinyl acetate aqueous solution Partially saponified polyvinyl acetate having a molecular weight of 88,000 and a degree of saponification of 87% was added to distilled water and left to swell for 2 hours. Next, this aqueous solution was heated to 98° C. to completely dissolve it, and an aqueous solution containing 5% by weight of partially saponified polyvinyl acetate was prepared.

(2) 10% by weight Aerosil 200 aqueous solution Aerosil 200 manufactured by Nippon Aerosil Co., Ltd. was used as the silica-based fine particles. Add Aerosil 200 to distilled water and use a high speed mixer (
The mixture was stirred and dispersed at a rotational speed of 3 QOO rpm to prepare an aqueous solution containing 10% by weight of Aerosil 200.

Next, mix aqueous solution 3 of phosphoric acid and chromic anhydride from above
To 73.6 g, 106 g of the 5% by weight partially saponified polyvinyl acetate aqueous solution of (1) was added and heated to 90°C to reduce part of the hexavalent chromium ions to trivalent chromium ions. The weight ratio of hexavalent chromium to total chromium in the reduced aqueous solution is 0.60, and the weight ratio of PO4'- to total chromium is:
Next, 515.6 g of the above reduced aqueous solution (10% aerosil 200 aqueous solution of ① above)
was added to prepare a chromate treatment agent according to the present invention. The total chromium in the chromate treatment agent is 5i02
(Aerosil 200) had a weight ratio of 1.29.

Next, an example of manufacturing a polyethylene-coated steel pipe according to the present invention using the above-mentioned brimer and chromate treatment agent will be explained.

A steel pipe (200^ x 5500a + m length x 5.8mm thickness) was grid blasted, and the above chromate treatment agent I or ■ was applied to the surface of the pipe until the total amount of chromium deposited was 550IIg.
After printing to a thickness of 7 m' and baking at 190°C for 3 minutes, apply epoxy primer to a thickness of 50 μm.
After coating with a spray paint machine and curing, a modified polyethylene resin was applied to a film thickness of 200 μm.
Apply electrostatically to form a mouth, and apply polyethylene resin to 3.2
After extrusion coating was carried out using a T-die so that the diameter of the polyethylene-coated steel pipe (^) was 1 mm, the polyethylene-coated steel pipe (^) according to the present invention was manufactured by cooling. Adhesion test on the above coated steel pipe (measurement temperature: 100°C, peeling angle = 90 degrees, peeling speed: 50 m
m/win, ), hot salt water immersion test (immersion temperature: 100°C
, immersion time: 16,000 hours, adhesive strength test after immersion), cathode peel test [(Initial Holliday diameter 5 mmφ, electrolyte 3% NaCl, voltage -1.5 V (Cu/CuSO4,
standard electrode), peeling distance of the film after the test ((x-5)/
Table 5 shows the results.

As is clear from the results in Table 5, chromate treatment is applied as a base treatment for steel pipes, and phenol novolak-type diglycidyl ether alone or bisphenol A diglycidyl ether, bisphenol An epoxy primer consisting of an epoxy resin prepared by mixing AD diglycidyl ether or bisphenol F diglycidyl ether alone or a mixture of 2 f1 or more, a modified polyamine obtained by condensing m-xylene diamine and epichlorohydrin, and an inorganic pigment. By applying this, you can obtain unprecedentedly good results in high-temperature adhesion tests, hot salt water immersion tests, and high-temperature cathodic peel tests.

Table 2 *1 Manufactured by Yuka Shell Epoxy Co., Ltd. *2 Manufactured by Mitsui Petrochemical Industries, Ltd. Table 5 Table 5-2 Table 5-1 Table 5-3 Table 5-4 Table 5-6 Table 5-5 Table 5-7 Table 5-8 Table 5-9 (Effects of the invention) As is clear from the examples, the polyolefin-coated steel material according to the present invention has a lower base material than the conventional polyolefin-coated steel material. Since it has an epoxy primer layer with excellent heat salt water resistance, it has excellent high temperature adhesion, heat salt water resistance, and high temperature cathode peeling resistance, and has the remarkable effect of providing an unprecedented polyolefin-coated steel material.

[Brief explanation of drawings]

FIG. 1 is a partial cross section of a polyolefin-coated steel material according to the present invention, and FIG. 2 is a schematic diagram showing an example of manufacturing a polyolefin-coated steel pipe as an example of the polyolefin-coated steel material according to the present invention. 1: Steel material 2: Chromate treatment agent 3: Phenol novolax type glycidyl ether alone, or bisphenol A diglycidyl ether, bisphenol AD diglycidyl ether, or bisphenol F diglycidyl ether An epoxy resin made by mixing ether alone or a mixture of two or more,
Epoxy primer layer composed of a modified polyamine obtained by condensing m-xylene diamine and epichlorohydrin, and an inorganic pigment: Modified polyolefin resin layer: Polyolefin resin layer: Chromate treatment agent coating device: Heating device: Epoxy primer coating device: Post-heating device 0 : Modified polyolefin resin coating equipment 1 : T-die 2 : Cooling equipment and 4 other people

Claims (1)

[Scope of Claims] In order from the inside of the steel surface, a chromate treatment agent layer, an epoxy primer layer containing the following three components (a), (b), and (c) as essential components, a modified polyolefin resin layer, and Polyolefin-coated steel material with excellent heat and salt water resistance characterized by laminating polyolefin resin layers (a) Phenol novolac type glycidyl ether alone, or bisphenol A, AD, or F added to the phenol novolac type glycidyl ether Epoxy resin consisting of diglycidyl ether alone or a mixture of two or more (b) Modified polyamine obtained by condensing m-xylene diamine and epichlorohydrin (c) Inorganic pigment