JP2640703B2 - Method for producing resin-coated metal plate by irradiation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for coating a metal plate with a radiation-curable solventless adhesive, immediately laminating a plastic film, and then applying a topcoat which cures upon irradiation. Alternatively, or not, it relates to a method for producing a resin-coated metal plate by irradiating radiation.

[0002]

2. Description of the Related Art Conventionally, as a method of manufacturing a resin-coated steel sheet by laminating a plastic film on a metal plate, a method of heating using an oven or the like is generally used. And then curing the adhesive in an oven and laminating a plastic film while the metal plate is being heated.

[0003] However, in this case, there are problems in terms of productivity due to restrictions on the length of the oven and the furnace temperature, and strict management is also required in terms of pollution control for treating the solvent discharged from the adhesive. Required. In addition, the laminated plastic film is also subjected to heat treatment as a result, and the film may be melted and the desired performance may not be obtained.

As a method of solving the drawbacks of the method using heating using an oven or the like, a method using irradiation with radiation has recently attracted attention. Instead of a heat-curable adhesive, an adhesive that can be cured by irradiation with radiation is used. A method has been proposed in which a plastic film is laminated immediately after being applied to a metal plate, and then the adhesive layer is cured by irradiating radiation from above the plastic film to produce a resin-coated steel sheet.

[0005] For example, Japanese Patent Application Laid-Open No.
8-174475, JP-A-59-86676 and JP-A-62-236733. In these methods, a heat treatment is basically unnecessary in a step of laminating a plastic film on a metal plate, and a long oven is not required. Therefore, the manufacturing process can be simplified and the laminated plastic film is heated. However, the adhesion between the metal plate and the plastic film is insufficient.

On the other hand, the thermoplastic resin is modified by irradiating it to a thermoplastic resin or a mixture of a thermoplastic resin and various crosslinking assistants, thereby improving heat resistance, water resistance, chemical resistance, oil resistance, and oil resistance. Attempts have been made to improve aging. These methods are described, for example, in JP-A-52-739.
No. 48, JP-A-58-42629, JP-A-61-29
There is a proposal such as 1626 gazette.

[0007]

As a method for improving the conventional method of manufacturing a resin-coated metal plate by using a heat treatment, a method by irradiation with radiation is disclosed. Adhesion is insufficient and improvement is needed. In addition, plastic films having various properties improved by irradiation with radiation are expensive, and resin-coated metal plates obtained by laminating these films increase costs and are economically problematic.

[0008]

According to the present invention, a metal plate surface is coated with a solventless adhesive, and immediately after a plastic film is laminated, a top coat which is cured by irradiation is applied or not. Irradiation cures the adhesive and simultaneously modifies the laminated plastic film by a cross-linking reaction or cures the overcoating agent to efficiently and inexpensively produce resin-coated steel sheets with excellent adhesion, workability and various properties. It is a method that can be manufactured.
Hereinafter, the present invention will be described in detail.

In the method of the present invention, the metal plate is
In addition to steel plate, stainless steel plate, aluminum plate or copper plate, these metal plates are subjected to zinc plating, chromium plating, tin plating, nickel plating or alloy plating of these metals, and multilayer plating, and further chromate treatment It is possible to use a metal plate that has been subjected to a chemical conversion treatment such as a phosphate treatment, and it can be arbitrarily selected according to its purpose and use.

The radiation-curable adhesive used in the method of the present invention has a number average molecular weight of 10,000 to 550 based on monomers, oligomers and prepolymers having an unsaturated bond which can be cured by irradiation with radiation. It is characterized by containing 2,000 polymer resins and a silane coupling agent, and exhibits extremely excellent adhesion to a metal plate and a laminated plastic film.

Monomers curable by irradiation with radiation
Is 2-ethylhexyl acrylate, tetrahydrofluorallyl acrylate, N-vinyl-2-pyrrolidone,
Monofunctional monomers such as dicyclopentenyl acrylate
And neopentyl glycol-diacrylyl-
And various polyfunctional monomers such as trimethylolpropane triacrylate and pentaerythritol tetraacrylate. Oligomers or prepolymers curable by irradiation with radiation include various acrylates such as polyester acrylates, epoxy acrylates, urethane acrylates as well as polyol acrylates. Can be used. If necessary, a mixture of two or more of these monomers, oligomers or prepolymers can be used.

Number average molecular weight 10,000 to 550,00
Acrylic resin, polyamide resin,
Examples include polyester resin, cellulose resin, epoxy resin, vinyl acetate resin, vinyl chloride resin, and butyral resin. The polymer resin has an effect of reducing contraction stress generated when the adhesive is rapidly cured by irradiation of radiation, and extremely effectively acts on improving the adhesion of the plastic film laminated with the metal plate. The amount of the polymer resin is desirably 2 to 70% by weight based on the monomer, the oligomer or the prepolymer. If the content is 2% by weight or less, the effect is not seen, and if the content is 70% by weight or more, the effect is the same, and the viscosity of the adhesive is undesirably increased.

Examples of the silane coupling agent include vinyltrimethoxysilane, N- (2aminoethyl) 3-aminopropyltrimethoxysilane, 3-glycidyloxypropyltrimethoxysilane, and 3-methacryloxypropyltrimethoxysilane. A compound containing a methoxy group or an ethoxy group as a functional group and a vinyl group, an amino group, an epoxy group, a methacryloxy group, or the like can be used. The silane-based coupling agent exhibits an excellent effect particularly on improving the adhesion to a metal plate. The amount of the silane coupling agent is preferably in the range of 0.01 to 5% by weight. When the content is 0.01% by weight or less, the effect is not seen, and when the content is 5% by weight or more, the effect is the same.

The radiation-curable adhesive can be applied by a commonly used roll coater, gravure coater, knife coater or spray method. The thickness of the radiation-curable adhesive can be arbitrarily determined according to the purpose.
0 μm is desirable.

Next, in the method of the present invention, plastic films to be laminated include olefin resins such as polyethylene and polypropylene, polyester, acrylic, polyvinyl chloride, ethylene-vinyl acetate copolymer, polyamide, ethylene, and the like. -Propylene rubber or styrene-butadiene rubber can be used. The thickness of the film can be determined according to the purpose, but is preferably 3 to 1,000 μm. After laminating these films on a metal plate via an adhesive curable by irradiation with radiation, a cross-linking reaction is caused by irradiating the film with 10 to 1,000 kGy from above, and heat resistance, water resistance, Chemical properties, oil resistance and aging resistance can be improved, and at the same time, it can be firmly adhered to the adhesive layer.

Further, depending on the type of plastic film used, a crosslinking aid may be added in an amount of 0.1 to increase the crosslinking rate.
Films containing from 1 to 20% by weight can be used.
When a crosslinking assistant is blended, the crosslinking reaction proceeds with a lower radiation dose as compared with the case where it is not blended, so that there is a great economic effect. Further, the adhesion between the plastic film and the adhesive layer can be further improved by blending a crosslinking aid. This is considered to be because a chemical reaction occurs between the laminated plastic film and the adhesive layer due to the irradiation of the radiation, and the adhesive adheres firmly. It is necessary to select an appropriate compound for the crosslinking aid depending on the plastic film to be used, and the compound is kneaded in the resin when the film is formed. If necessary, various commonly used additives such as a coloring pigment, a stabilizer and a lubricant can be simultaneously kneaded.

As a crosslinking aid for the polyethylene film, for example, polyfunctional acrylic monomers such as dipropadyl maleate, triallyl cyanurate and ethylene dimethacrylate or allyl monomers can be used. it can.

In the case of polypropylene alone, when a resin alone is used, a main chain scission reaction occurs preferentially by irradiation, so that unsaturated double bonds curable by irradiation to side chains are introduced or copolymerized with a vinylsilane compound. It is desirable to use the oxidized polypropylene and further blend an antioxidant such as hindered amine.

For polyester, acrylic, polyvinyl chloride, ethylene-vinyl acetate, ethylene propylene rubber or styrene-butadiene rubber films,
Trimethylolpropane triacryle as a crosslinking aid
For example, a polyfunctional acrylic monomer having an unsaturated double bond at the terminal, such as a monomer, can be used.

For the polyamide film, a crosslinking aid such as triallyl isocyanurate and triallyl cyanurate can be used.

In the method of the present invention, the surface of the metal plate is coated with a non-solvent type adhesive which cures with radiation, a plastic film is immediately laminated, and then a top coat which cures with radiation is applied. Subsequently, the resin-coated steel sheet having more excellent properties can be manufactured by irradiating radiation to cure the adhesive and modify the plastic film and simultaneously cure the overcoating agent.

Examples of the topcoating agent which is cured by irradiation include monomers, oligomers or prepolymers having an unsaturated double bond such as a vinyl group or an acryloyl group.
Species or a mixture of two or more can be used.

The top coat can be applied by a commonly used roll coater, gravure coater, knife coater or spray method. Also,
The coating thickness of the top coat can be arbitrarily determined according to the purpose, but is preferably 0.1 to 50 μm.

By providing a radiation-cured top coat layer on a plastic film, properties such as stain resistance, heat resistance, water resistance, chemical resistance, oil resistance, and aging resistance can be further improved, and the hardness can be improved. And the properties such as scratch resistance can be improved.

The radiation includes γ-rays, α-rays, electron beams and the like, and the method used in the present invention is preferably an electron beam method. Since the penetrating power of the electron beam depends on the accelerating voltage, the accelerating voltage is determined by the thickness of the plastic film to be used, but is usually used in the range of 100 to 1,000 kV. Hereinafter, the present invention will be described with reference to examples.

[0026]

Example 1 A plating amount of 10 g / m ² and a post-treatment of Cr
Plate thickness of 20 mg / m ² with chromate treatment.
N-vinyl-2 on the surface of a 5 mm electrogalvanized steel sheet
Urethane acrylate 28 having 20% by weight of pyrrolidone, 20% by weight of dicyclopentenyl acrylate and a number average molecular weight of 1,000 and having two acryloyl groups per molecule;
5 μm of a radiation-curable adhesive composed of 30% by weight of a high-molecular-weight acrylic resin having a number average molecular weight of 70,000 and 2% by weight of 3-aminopropyltrimethoxysilane
Acrylic oligomer (Aronix M-80, manufactured by Toa Gosei Chemical Co., Ltd.)
60) After laminating a 150 μm thick polyvinyl chloride film containing 10% by weight and 20% by weight of 2-ethylhexyl phthalate as a plasticizer, an electron beam of 50 kG was applied from above the polyvinyl chloride film at an acceleration voltage of 300 kV.
Irradiation was performed to produce a resin-coated steel sheet.

The obtained resin-coated steel sheet was subjected to JIS K6
After performing girder Erichsen overhanging 8 mm according to the method shown in 744, a peel test was performed on the laminated polyvinyl chloride film using dentist's tweezers. As a result, no peeling of the film was observed and good adhesion was observed. Obtained. In addition, a sample on which a girder Erichsen overhang was 8 mm was heated at 120 ° C.
As a result of the heat resistance test for 100 hours and the immersion test in boiling water at 100 ° C for 1 hour, no peeling of the film was observed in any case.
Excellent heat resistance and water resistance. On the other hand, when the hardness of the polyvinyl chloride film was measured by a durometer A type, it was 91 before lamination, but was 50 kGy after lamination.
Irradiation of the electron beam increased the hardness to 95.

[0028]

Example 2 The amount of plating was 10 g / m ² and Cr was used as a post-treatment.
Plate thickness of 20 mg / m ² with chromate treatment.
On a surface of a composite electrogalvanized steel sheet containing 5 mm of zinc as a main component and containing 1% of cobalt and 0.1% of molybdenum, a radiation-curable adhesive having the composition shown in Example 1 having a thickness of 5 μm is applied.
After application, immediately after laminating a low-density polyethylene film having a thickness of 35 μm, an electron beam was irradiated at 100 kGy from above the polyethylene film under the conditions of an accelerating voltage of 200 kV to prepare a resin-coated steel sheet.

After the obtained resin-coated steel sheet was overhanged by Ericksen 6 mm by the method shown in Example 1, the laminated polyethylene film was subjected to a peeling test using tweezers for dentists. No good adhesion was obtained. In addition, the girder Erichsen overhang 6m
As a result of performing a 1-hour boiling water immersion test on each of the samples subjected to m, no peeling of the film was observed in any case, and excellent water resistance was exhibited. Further, the obtained resin-coated steel sheet was immersed in concentrated hydrochloric acid, and as a result of measuring the breaking strength at a high temperature of the polyethylene film after the electron beam irradiation peeled off from the steel sheet, the result was 120.
It was 90 g / mm ² at ℃, and good heat resistance was obtained. The gel fraction was measured to be 65%,
Good crosslinkability was shown.

[0030]

Example 3 20% by weight of N-vinyl-2-pyrrolidone, 20% by weight of dicyclopentenyl acrylate, and a number average molecular weight of 1,000 were applied to the surface of the composite electrogalvanized steel sheet shown in Example 2. 28% by weight of urethane acrylate having two acryloyl groups in the molecule, number average molecular weight of 10.0
A radiation-curable adhesive consisting of 30% by weight of a saturated polyester resin and 2% by weight of vinyltrimethoxysilane is applied to a thickness of 5 μm and immediately contains 2% by weight of a hindered amine as an antioxidant and is unsaturated in side chains. After laminating a 100 μm-thick polypropylene resin film (ROP, manufactured by Mitsubishi Yuka Co., Ltd.) into which double bonds have been introduced, the resin film is irradiated with 50 kGy of electron beam from above the polypropylene film under the condition of an acceleration voltage of 200 kV. A steel plate was created.

The obtained polypropylene-based resin-coated steel sheet was subjected to the method shown in Example 1 to extend Eirsen Ericksen 8
As a result, no peeling of the film was observed, and good adhesion was obtained. The obtained polypropylene-based resin-coated steel sheet was subjected to a heat resistance test at 170 ° C. for 1 hour. As a result, no melting, cracking or large discoloration of the film was observed, and good heat resistance was exhibited. Further, the laminated polypropylene-based film was peeled off by a method similar to the method shown in Example 2, and the gel fraction was measured. As a result, the gel fraction was 90%, indicating extremely high crosslinkability.

[0032]

Embodiment 4 On the surface of a cold-rolled steel sheet having a thickness of 0.3 mm,
6 g / m ² tin plating, followed by 5 m as Cr
g / m ² of chromate treatment, and the radiation-curable adhesive shown in Example 1 was applied at a thickness of 5 μm, and immediately thereafter, a film thickness of 50 μm containing 2% by weight of triallyl isocyanurate as a crosslinking aid was used. Nylon 12 film is laminated,
An electron beam was irradiated at 50 kGy from above the film under the condition of an acceleration voltage of 200 kV to produce a nylon resin-coated steel sheet.

The obtained nylon resin-coated steel sheet was overhanged by Eirsen's Ericksen 6 mm by the method shown in Example 1. As a result, no peeling of the film was observed and good adhesion was obtained. Further, the obtained nylon-based resin-coated steel sheet was heated at 350 ° C.
As a result of immersion in a solder bath for 5 seconds, melting of nylon resin,
No discoloration or the like was observed, indicating that the composition exhibited excellent heat resistance.

[0034]

Embodiment 5 The radiation-curable adhesive shown in Embodiment 1 was applied to the surface of the electrogalvanized steel sheet shown in Embodiment 1 by 5 μm.
The polyvinyl chloride film shown in Example 1 was immediately laminated, followed by trimethylolpropane triacrylate 35% by weight, dicyclopentenyl acrylate 20% by weight, and an acrylic resin. 25% by weight of oligomer (manufactured by Shin-Nakamura Chemical Co., Ltd., NK Oligo U-6HA) and urethane acrylate (manufactured by Takeda Pharmaceutical Co., Ltd., UV
-90X-06NS) After applying a radiation-curable top coat of 20 μ% in thickness of 10 μm, an electron beam was applied from above the top coat layer at an acceleration voltage of 200 kV under the conditions of an acceleration voltage of 200 kV.
Irradiation with kGy produced a polyvinyl chloride resin-coated steel sheet.

The obtained polyvinyl chloride resin-coated steel sheet was
After performing a girder Erichsen overhanging 8 mm by the method shown in Example 1, the laminated polyvinyl chloride film was subjected to a peeling test using dentist's tweezers. As a result, no peeling of the film was observed and good adhesion was obtained. Obtained. In addition, the obtained polyvinyl chloride resin-coated steel sheet was subjected to JIS K54.
After making a 1 mm wide cut in a grid pattern with a cutter knife according to 00, a peeling test was performed with an adhesive tape. As a result, no peeling of the overcoating layer was observed, and good adhesion was obtained. Was done. An oil-based magic ink (black, red, blue) was applied to the surface of the polyvinyl chloride resin-coated steel sheet at a width of 5 mm and a length of 2 mm.
After applying cm, the ink was allowed to stand for 24 hours, and was wiped off with a gauze containing methyl alcohol. As a result, all color inks could be removed cleanly, and good stain resistance was exhibited.

[0036]

Comparative Example 1 N-vinyl-2 was formed on the surface of the electrogalvanized steel sheet shown in Example 1 by removing the polymer acrylic resin and 3-aminopropyltrimethoxysilane from the radiation-curable adhesive shown in Example 1. An adhesive consisting of 25% by weight of pyrrolidone, 35% by weight of dicyclopentenyl acrylate and 40% by weight of urethane acrylate having a number average molecular weight of 1,000 and two acroyl groups per molecule to a thickness of 5 μm. Immediately after coating, a 150 μm-thick polyvinyl chloride film containing 20% by weight of 2-ethylhexyl phthalate as a plasticizer is laminated, and an electron beam is applied from above the polyvinyl chloride film at an accelerating voltage of 300 kV under a condition of 50 kV.
Gy irradiation was performed to prepare a resin-coated steel sheet.

The obtained resin-coated steel sheet was overhanged by Ericksen 8 mm by the method shown in Example 1. As a result, peeling of the polyvinyl chloride film at the overhang of Ericksen was observed, and the adhesion was poor. . In addition, as a result of performing a heat resistance test at 120 ° C. for 1 hour and a boiling water immersion test at 100 ° C. for 1 hour, the exfoliated portion of the film was further expanded in each case, And water resistance were poor. The hardness of the polyvinyl chloride film was measured by a durometer A type. As a result, the hardness was 91 as before lamination, and no increase in hardness was observed.

[0038]

Comparative Example 2 A solvent-type polyolefin-based adhesive was applied to the surface of a composite electrogalvanized steel sheet containing zinc as a main component and containing 1% of cobalt and 0.1% of molybdenum as shown in Example 2 to a dry film thickness of 5 μm. After heating the steel plate in a gas oven at 300 ° C until the temperature of the steel plate reaches 200 ° C,
A polyethylene coated steel sheet was prepared by laminating 5 μm low density polyethylene films.

The resulting polyethylene-coated steel sheet was immersed in concentrated hydrochloric acid, and the polyethylene film peeled off from the steel sheet was measured for the breaking strength at high temperature (120 ° C.). Heat resistance was poor. The gel fraction was measured to be 0%, and no cross-linking component was observed.

[0040]

According to the method of the present invention, a resin-coated metal plate having excellent properties such as adhesion, workability and heat resistance can be efficiently and inexpensively manufactured.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical indication location C08J 5/12 C08J 5/12 7/00 305 7/00 305 // B29K 105: 24 B29L 9: JP-A-62-273834 (JP, A) JP-A-62-135535 (JP, A) JP-A-61-179281 (JP, A) JP-A-57-140120 (JP, A) JP-A-63-315212 (JP, A) JP-A-61-215044 (JP, A) JP-A-57-2755 (JP, A)

Claims (4)

(57) [Claims] 1. A method for producing a resin-coated metal plate, in which an adhesive is coated on a surface of a metal plate, a plastic film is laminated thereon, and radiation is applied, wherein the adhesive is cured by irradiation. An adhesive, wherein the plastic film includes a crosslinking aid,
A method for producing a resin-coated metal plate which is any of polyester, acrylic, polyvinyl chloride, polyamide, ethylene propylene rubber or styrene-butadiene rubber. 2. The solvent-free adhesive has a number average molecular weight of 10,000 to 550,00 based on a monomer, oligomer or prepolymer having an unsaturated bond which is cured by radiation.
2. The method for producing a resin-coated metal sheet according to claim 1, wherein the polymer resin is contained in an amount of 2 to 70% by weight and a silane coupling agent is further contained in an amount of 0.01 to 5% by weight. 3. A method for producing a resin-coated metal plate, in which an adhesive is coated on the surface of a metal plate, a plastic film is laminated thereon, and radiation is applied, wherein the adhesive is cured by irradiation. An adhesive, wherein the plastic film is a polyester, acrylic, polyvinyl chloride, polyamide, ethylene propylene rubber or styrene-butadiene rubber containing a crosslinking aid, and is cured by irradiation after the film is laminated. A method for producing a resin-coated metal sheet, comprising applying a topcoating agent. 4. The solvent-free adhesive has a number average molecular weight of 10,000 to 550,000 based on a monomer, oligomer or prepolymer having an unsaturated bond which is cured by radiation.
4. The method for producing a resin-coated metal sheet according to claim 3, wherein the polymer resin is contained in an amount of 2 to 70% by weight and a silane coupling agent is further contained in an amount of 0.01 to 5% by weight.