JPH0655299B2 - Surface modification of organic resin coated steel - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for modifying the surface of a steel material by graft-polymerizing a monomer for surface reforming on the surface of the organic resin coated steel material.

(Prior Art) The organic resin used in the production of the organic resin-coated steel material has a balance of various characteristics such as adhesion, corrosion resistance, and weather resistance, except for large lots whose applications have been discriminated in advance. For this reason, although the application is special, if the lot is small, it is necessary to use an organic resin coated with a balanced property. In addition, even for a large lot, if the required characteristics are satisfied, other characteristics are significantly impaired, so that the requirements may not be satisfied in some cases.

Therefore, in order to deal with such special applications, different organic resins are adhered to the organic resin surface, or different organic resin solutions are applied and dried to form different organic resin layers on the organic resin surface. Therefore, it has been conventionally performed to impart characteristics suitable for the intended use. That is, these methods particularly require applications such as hydrophilicity, water repellency, oil repellency, antistatic property, solvent resistance, water resistance, acid resistance, alkali resistance, low friction property or non-adhesion property. In this case, it is an excellent method for further imparting those characteristics.

(Problems to be Solved by the Invention) However, in these methods, the interlayer adhesive force between the organic resin of the steel material and the different organic resin is low. Further, the thickness of the coating film formed by different kinds of organic resins is preferably several μm or more in order that those characteristics sufficiently act, and therefore the original characteristics of the organic resin of the steel material are impaired.

(Means for Solving the Problems) Then, as a result of intensive investigations by the present inventors in order to solve the above problems, as a result, the surface-modifying monomer or monomer solution was applied to the surface of the organic resin-coated steel material, and After the sheet-shaped material is laminated on the sheet-shaped material, electron beam is irradiated from the sheet-shaped material side to graft-polymerize the monomer onto the organic resin surface of the steel material, and then the laminated sheet-shaped material is peeled off and remains on the organic resin surface. The surface of the organic resin-coated steel material was modified by the method of removing unreacted monomer or monomer solution.

In the present invention, the monomer liquid or the monomer solution is applied to the surface of the steel material coated with the organic resin, and the sheet-shaped material is laminated on the surface of the steel material. Since it is a surface, the monomer solution and the monomer solution are discontinuous and a uniform film is not formed. However, when the sheet material is laminated on them, the monomer solution or the monomer solution is kept thin between the steel material and the sheet material by the capillary action. By irradiating the laminated sheet-shaped material with an electron beam in this state, the electron beam can easily pass through the monomer layer, and the monomer can be graft-polymerized on the entire surface of the organic resin of the steel material. Therefore, if the sheet-shaped material is peeled off after the electron beam irradiation and the unreacted monomer or monomer solution on the surface of the organic resin is removed, only the grafted monomer remains on the surface of the steel material and the surface can be modified.

The monomer to be applied to the surface of the steel material coated with an organic resin in the present invention is a monomer simple substance having an electron beam reactive functional group (ethylenically unsaturated double bond), a monomer solution obtained by adding a solvent thereto, or a mol salt or the like. What added the polymerization inhibitor may be used. These may be applied by a known method such as spraying, curtain flow or roll coating.

The sheet-shaped material laminated on the monomer is laminated so as to be in close contact with the organic resin of the steel material via the monomer liquid or the monomer solution. This sheet material is a plastic film, a metal film deposited on this film, a metal foil,
Paper, resin-coated paper, metal evaporated paper, or the like is used.

Since the monomer is covered with the sheet-shaped material, the irradiation of radiation may be carried out in an air atmosphere without deterioration of graft polymerization due to oxygen.

The method of the present invention can be applied even if the shape of the steel material is plate-shaped, tubular or shaped steel, and the coating organic resin is polyester resin,
Polyurethane resin, polyvinyl chloride resin, acrylic resin, polyolefin resin, epoxy resin, and fluororesin can be applied.

(Example) Example 1 Hot-dip galvanized steel sheet (thickness 0.5 mm, zinc adhesion amount 60 g
/ M ² ), using hot pressing, a high density polyethylene film (thickness 100 μm) or modified polyethylene film for adhesion (thickness 30 μm) was heat-sealed to the organic resin coated steel sheet, and methacrylic acid or methacrylic acid as a monomer-2 -While applying hydroxyethyl with a bar coater # 30, a biaxially oriented polyester film (thickness: 25 μm) was laminated, and the thickness of the applied monomer was reduced by laminating.

Next, from the polyester film side, an acceleration voltage of 200
An electron beam was irradiated under the conditions of KeV, electron flow of 10 mA, and dose of 5 Mrad to graft-polymerize methacrylic acid or 2-hydroxyethyl methacrylate onto the surface of the steel sheet. After the polymerization, the polyester film was removed, and the surface of the steel sheet was ultrasonically cleaned in methanol and water for 5 minutes each and dried.

After that, the contact angles of these steel plates with water were measured, and those obtained by graft-polymerizing methacrylic acid were 54 °,
The product obtained by graft-polymerizing 2-hydroxyethyl methacrylate was 63 °, and the contact angle of untreated organic resin-coated steel sheet was 1
Hydrophilicity was imparted to 04 °.

Example 2 As the organic resin-coated steel material, the same plated steel sheet as in Example 1 was subjected to a phosphate treatment, and an epoxy resin-based undercoat paint and a polyester resin-based overcoat paint were respectively dried to a coating film thickness of 5 μm and 15 μm and baked to dry. Example 1 using the coated steel sheet prepared above and trifluoroethyl methacrylate or methacrylic acid as the surface-modifying monomer.
The surface of the coated steel sheet was modified in the same manner as above.

As a result, the contact angle with respect to water was 116 ° in the case of modification with trifluoroethyl methacrylate and 69 ° in the case of modification with methacrylic acid. The latter was imparted with hydrophilicity.

Comparative Example 1 The high-density polyethylene film-coated steel sheet used in Example 1 was used as the surface-modified organic resin-coated steel material, and the step of laminating the biaxially stretched polyester film after the monomer application in Example 1 on this steel sheet was omitted. Except that
Otherwise, the display was modified in the same manner as in Example 1.

As a result, none of the monomers was evenly coated with a bar coater, resulting in a mottled pattern and a non-uniform contact angle with water.

Comparative Example 2 In the method of Example 2, the surface modification was carried out in the same manner as in Example 2, omitting the step of laminating the film after coating the coated steel sheet with the monomer. As a result, the coated state of the monomer on this steel sheet and the contact angle with water were the same as in Comparative Example 1.

(Effect) As described above, according to the present invention, the monomer of the different organic resin is graft-polymerized with the steel material-coated organic resin to modify the surface. Therefore, the bond between the steel material-coated organic resin and the different organic resin is strong. Further, since the heterogeneous organic resin removes the monomer which is not graft-polymerized, the film thickness thereof is thin, and the important characteristics inherent to the steel material-coated organic resin are not impaired. Further, since the graft polymerization is carried out by thinly and uniformly holding it with a sheet-shaped material obtained by laminating a monomer applied on a steel material, the monomer can be uniformly graft-polymerized on the entire organic resin surface of the steel material even in a low voltage type electron accelerator.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenichi Masuhara 1 at 7 Ichikawa Research Laboratories, Takatani Shinmachi, Ichikawa City, Chiba Prefecture (56) References JP-A-60-68083 (JP, A) Kaisho 59-177169 (JP, A)

Claims (1)

[Claims] 1. A surface-modifying monomer or monomer solution is applied to the surface of an organic resin-coated steel material, a sheet-shaped material is laminated thereon, and then an electron beam is irradiated from the sheet-shaped material side to remove the monomer. Surface modification of organic resin coated steel characterized by graft polymerization on the surface of organic resin of steel and then peeling off the laminated sheet material to remove unreacted monomer or monomer solution remaining on the surface of organic resin Law.