JP3096209B2 - Water-resistant printed film laminated steel sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-resistant printed film laminated steel sheet which is suitable for manufacturing members for products used around water.

[0002]

2. Description of the Related Art A laminated steel sheet in which a printed polyethylene terephthalate film having a plain or patterned pattern printed on its surface is laminated on the surface of the steel sheet is a printed polyethylene terephthalate film.
Since a PET film (hereinafter referred to as a printed PET film) has a higher hardness than an PVC film and is inexpensive, it has been conventionally used for exterior parts such as home electric appliances and heating equipment, interior building materials or equipment. This laminated steel sheet has conventionally been manufactured by providing a colored adhesive layer containing a pigment on the surface of the steel sheet, and laminating a printed PET film thereon so that the printed surface is on the adhesive layer side. Here, the reason why the pigment is added to the adhesive layer is to prevent the ground color of the steel sheet from appearing in appearance.

[0003] However, since the laminated steel sheet has a pigment added to the adhesive layer, the water resistance is inferior. When a boiling water immersion test or a moisture resistance test is performed, water penetrates into the adhesive layer. Then, the film swells or peels off from the adhesive layer. For this reason, there is a problem in using it for a member of a product around water such as an exterior material of an electric washing machine or kitchen equipment. Therefore, a method has been proposed in which a printed PET film is laminated on a steel sheet using only a printing ink layer without using an adhesive (Japanese Patent Application Laid-Open No. 59-232852). However, it is difficult to achieve both coloration and adhesive strength in the printing ink layer, and swelling or peeling of the film occurs as in the case of the adhesive layer.

[0004]

SUMMARY OF THE INVENTION The present invention is to provide a printed film laminated steel sheet which has solved the problem of water resistance of the adhesive layer.

[0005]

According to the present invention, a colored primer layer of a thermosetting resin is provided between a steel sheet and an adhesive layer, and the adhesive layer is free of a pigment.

[0006]

Since the primer layer is a thermosetting resin, the primer layer becomes a denser matrix than the adhesive. Therefore, even if the pigment is added, the matrix maintains its dense state,
Prevents water penetration. On the other hand, since the adhesive layer does not contain a pigment, the compactness is improved, water does not easily penetrate, and the adhesive strength between the upper and lower primer layers and the printed PET film is increased.

The resin of the thermosetting colored primer layer preferably has a high adhesive strength to a steel plate. For example, an epoxy resin or a polyester resin may be used.
A curing agent may be added to increase the density of the pigment as a matrix. As the curing agent, melamine resin, urea, isocyanate resin and the like may be used. The primer layer preferably has a dry coating thickness of 2 to 20 μm. In addition, a coloring pigment, a rust-preventive pigment, and an extender pigment may be added to the primer layer as needed.

The adhesive layer includes a primer layer and printed PET.
There is no particular limitation as long as the film can be bonded,
For example, a polyester resin or a polyurethane resin may be used. No pigment is added to this adhesive layer. However, it is possible to add other components to increase the adhesion. The thickness is preferably from 1 to 20 [mu] m in terms of the dry coating thickness.

Since the color tone of the primer layer can be seen through the adhesive layer, the ground pattern of the printed PET film can be used. However, since it is difficult to exactly match the two color tones, the film has a pattern having a ground pattern. It is preferred to use As the printing ink, those obtained by blending various additives in addition to pigments in base resins such as acrylic, polyester and polyurethane can be used. Among them, two-pack polyurethane based is used as the base resin. The one using the thing is preferable.

In the production of the laminated steel sheet of the present invention, a plated steel sheet, a stainless steel sheet or the like is subjected to a pre-treatment such as a chromate treatment or a phosphate treatment to obtain a primer such as an epoxy resin or a polyester resin. The paint is roll-coated,
After coating by a known method such as a curtain flow method or a spray method, the film is baked and dried at 120 to 280 ° C for 20 to 90 seconds, and an adhesive layer such as a polyester resin or a polyurethane resin is further coated thereon with a primer. The layer may be formed in the same manner as the layer, and the printed PET film may be laminated when the adhesive layer is in a molten state.

[0011]

【Example】

Example 1 A hot-dip galvanized steel sheet (sheet thickness: 0.5 mm, zinc coating amount: 45 g / m ^{2 on} one side) was subjected to coating-type chromate treatment, and an epoxy resin-based white primer paint [curing agent: melamine resin, resin / Pigment = 1/1 (weight ratio)] at a dry film thickness of 1
After forming a primer layer by applying the film to a thickness of 0 μm and baking and drying, a polyester-polyurethane resin-based non-colored adhesive (curing agent: isocyanate resin) is dried to a thickness of 5 μm. , Bake-dry, and immediately print PET with the laminated surface facing the printed surface
Film A was laminated at a lamination temperature of 200 ° C. Here, the printed PET film A is a 25 μm-thick corona-discharge treated PET film [manufactured by Toyobo Co., Ltd.]. After gravure printing with a printing ink of resin, solid printing was performed using the same printing ink. The obtained laminated steel sheet was subjected to a boiling water immersion test (immersion for 6 hours), but no swelling or peeling of the film was observed. A high-temperature wet test (temperature: 70 ° C., relative humidity: 98%) was performed for 500 hours, but no swelling or peeling of the film was observed.

Example 2 An alloyed hot-dip galvanized steel sheet (0.4 mm in thickness, 30 g / m ^{2 on} one side of zinc) was subjected to a coating-type chromate treatment, and a polyester resin-based gray color primer paint [cured] Agent: isocyanate resin, resin / pigment = 1/1 (weight ratio)] to a dry film thickness of 7 μm, and baking and drying to form a primer layer.
Polyester-polyurethane resin-based non-colored adhesive (curing agent: epoxy resin) is applied to a dry film thickness of 10 μm, baked and dried, and immediately printed PET film B with the laminated surface facing the printed surface Was laminated at a lamination temperature of 160 ° C. Here, the printed PET film B was a gravure-printed or solid-printed grain-patterned pattern of a 25 μm-thick polyester resin-coated PET film [manufactured by Teijin Limited] with the same printing ink as in Example 1. Using. The obtained laminated steel sheet was subjected to the same boiling water immersion test and high-temperature wetness test as in Example 1, but no swelling or peeling of the film was observed.

Example 3 A coating type chromate treatment was applied to an alloyed hot-dip galvanized steel sheet (0.6 mm in thickness, 60 g / m ^{2 on} one side of zinc) to obtain an epoxy resin-based beige primer paint [ Curing agent: isocyanate resin, resin / pigment = 1/1 (weight ratio)] to a dry coating thickness of 5 μm and baking and drying to form a primer layer.
Polyester-polyurethane resin non-colored adhesive (curing agent: epoxy resin) is applied to a dry film thickness of 3 μm, baked and dried, and immediately printed PET film C with the laminated surface facing the printed surface Was laminated at a lamination temperature of 160 ° C. Here, the thickness of the printed PET film C is 2
A 5 μm polyester resin-coated PET film [manufactured by Teijin Limited] was gravure-printed on a Japanese paper pattern with a polyester-based resin-based printing ink and then solid-printed with the same printing ink. Was. The obtained laminated steel sheet was subjected to the same boiling water immersion test and high-temperature wetness test as in Example 1, but no swelling or peeling of the film was observed.

Example 4 A SUS304 stainless steel plate (0.6 mm thick) was subjected to a phosphate treatment, and an epoxy resin-based black primer coating material [curing agent: melamine resin, resin / pigment = 1 / 0.6 (weight) Ratio)] to a dry film thickness of 10 μm, baking and drying to form a primer layer, and then applying a polyester resin-based non-colored adhesive (curing agent: polyisocyanate) to the dry film. Apply to a thickness of 5 μm, bake and dry, and immediately print PET film D
Was laminated at a lamination temperature of 210 ° C. Here, print P
ET film D has 25μm thick easily-adhesive treated PET
A gravure print of a Japanese paper pattern on a film [manufactured by Toray Industries, Inc.] with the same printing ink as in Example 1 was used, followed by solid printing with the same printing ink. The obtained lamine
Immersion test (immersion for 10 hours), high-temperature wetness test (temperature: 70 ° C., relative humidity: 98%, test time: 10)
00 hours), no swelling or peeling of the film was observed.

[0015]

[Comparative example]

Comparative Example 1 In Example 1, the formation of the primer layer was omitted, and the dry coating thickness of the polyester-polyurethane resin-based non-colored adhesive was set to 10 μm. When the same boiled water immersion test as in Example 1 was performed on the obtained laminated steel sheet, the film was peeled off due to cohesive failure of the adhesive layer. On the other hand, no fine swelling was observed in the film in the high-temperature wet test.

Comparative Example 2 In Example 2, a polyester resin white primer was used instead of the polyester resin gray primer.
Paint [curing agent: isocyanate resin, resin / pigment = 1 /
1.2 (weight ratio)] to form a primer layer having a dry coating thickness of 10 μm. Also, instead of a polyether-polyurethane resin-based non-colored adhesive, a white colored one [curing agent: epoxy resin, resin / pigment = 1 / 1.2 (weight ratio)] was used, and the dry coating film thickness was 10 μm. Was formed. When the same boiled water immersion test as in Example 1 was performed on the obtained laminated steel sheet, the film was peeled off due to cohesive failure of the adhesive layer. In addition, the film was completely peeled off in the high-temperature wet test.

Comparative Example 3 In Example 3, an epoxy resin-based uncolored primer paint (curing agent: isocyanate resin) was used in place of the epoxy resin-based beige primer paint, and the dry coating thickness was 5 μm. Was formed. In addition, instead of a polyether-polyurethane resin-based uncolored adhesive, a beige colored one [curing agent: epoxy resin, resin / pigment = 1
/1.2 (weight ratio)] to form an adhesive layer having a dry coating thickness of 10 μm. The obtained laminated steel sheet was subjected to the same boiling water immersion test and high-temperature wetness test as in Example 1.
In the former, the end face of the film was largely peeled off, and in the latter, the film was completely peeled off due to cohesive failure of the adhesive layer.

[0018]

As described above, since the laminated steel sheet of the present invention is excellent in water resistance, the printed PET film peels or swells even when used for parts of products around water. Nothing.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Kenji Koshiishi 1 at Nisshin Steel Co., Ltd. Iron and Steel Research Laboratories, Coating and Coating Research Department, 7-7 Takayashinmachi, Ichikawa City, Chiba Prefecture (56) References JP-A-5-92508 (JP) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B32B 1/00-35/00

Claims (1)

(57) [Claims] A laminated steel sheet having a colored adhesive layer provided on the surface of a steel sheet and a printed polyethylene terephthalate film laminated on the adhesive layer such that the printed surface is on the adhesive layer side. A water-resistant printed film laminated steel sheet, characterized in that a colored primer layer of a thermosetting resin is provided between the adhesive layer and the adhesive layer.