JPH01202492A - Transfer sheet with hardenable protective layer and transfer method - Google Patents

Abstract

PURPOSE:To prevent a protective layer from flowing or being needlessly deformed and prevent the gloss of a thin metallic film layer from being lowered after transfer, by providing the protective layer by use of an inonizing radiation- curable resin which is solid at normal temperature in an uncured state and is thermoplastic, and setting the protective layer in a half-cured state. CONSTITUTION:A transfer sheet comprises a protective layer and at least a thin metallic film layer provided sequentially on a releasable side of a releasable sheet. The protective layer, for protecting the layer therebeneath after transfer, comprises a half-cured layer of an ionizing radiation-curable resin which is solid at normal temperature in an uncured state and is thermoplastic. Since the protective layer of the transfer sheet is preliminarily half-cured, the layer has high heat resistance, and is prevented from flowing by being melted by the heat at the time of transferring, with the result of affecting the thin metallic film layer to lose the metallic luster. In addition, since the protective layer is not completely cured, it retains transferability to a rugged surface, and can be cured after the transferring.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a transfer sheet capable of forming a protective layer with excellent surface strength by transfer, and a transfer method using the transfer sheet.

[Conventional technology]

Previous attempts have been made to make the layer closest to the surface after transfer using a hardening resin to protect the transferred image from wear and deterioration caused by chemicals. In particular, if the protective layer is made of ultraviolet curable resin or electron beam curable resin, no heat is required for curing.
It has the advantage of instant curing.

However, since ordinary ultraviolet curable resins and electron beam curable resins are sticky in their uncured state, it is difficult to apply the next layer after coating or printing. However, when attempting to provide such a film, there was a problem in terms of adhesion.

In addition, since the protective layer of the obtained transfer sheet has been cured and the entire transfer sheet has high rigidity, there is no problem in transferring it to a flat plate-like surface. It was difficult to transfer it to the surface.

Therefore, it is solid at room temperature in an uncured state, and
Attempts have been made to provide a protective layer using ionizing radiation-curable resins. It is possible to provide a protective layer with such resin by dissolving it in a solvent and applying/printing it, and it is also possible to apply/print the next layer without irradiating it with ionizing radiation after applying the protective layer. It has good adhesion and can be deformed like thermoplastic resin, so it can be transferred to uneven surfaces.
After transferring using the obtained transfer sheet, the protective layer can be cured by irradiation with ionizing radiation to improve the physical and chemical strength of the surface.

However, the above-mentioned protective layer is uncured on the transfer sheet, and its heat resistance is comparable to or worse than thermoplastic resin, so if too much heat is applied during transfer, the protective layer will melt and flow. As a result of affecting the metal thin film layer, there is a drawback that the metallic luster of the metal thin film layer becomes dull.

[Problems to be Solved by the Invention] The problem to be solved by the invention is to provide an ionizing radiation-curable resin that is solid at room temperature in an uncured state and is thermoplastic.
The purpose is to eliminate the above-mentioned drawbacks when providing a protective layer.

[Means to solve the problem]

In this invention, a protective layer is provided using "an ionizing radiation-curable resin that is solid at room temperature in an uncured state and is thermoplastic," and the protective layer is brought into a Burfkinia state. , we were able to solve the above problems.

That is, the present invention provides: ``A curable layer consisting of a half-cured ionizing radiation-curable resin that is solid at room temperature in an uncured state and is thermoplastic, on the release surface of a release sheet; ``A transfer sheet comprising, in order, a protective layer that protects the lower layer after transfer and at least a metal thin film layer,'' and ``A transfer sheet that is used to transfer onto the surface of an object to be transferred,
It also includes a "transfer method" characterized in that the transferred protective layer is then cross-linked and cured by irradiation with ionizing radiation.

[Effect]

According to this invention, the protective layer of the transfer sheet is half-cured in advance, so it has high heat resistance, and the heat during transfer melts and flows the protective layer, which affects the metal thin film layer and gives it a metallic luster. is prevented from being lost.

Moreover, since the protective layer is not completely cured, it also has transferability to uneven surfaces, and the protective layer can be cured after transfer.

[Specific explanation of configuration]

The transfer sheet of the present invention is most simply made of three layers: a release sheet, a protective layer, and a metal thin film layer. Other structures of the transfer sheet will be explained later.

Release sheet The material for the release sheet may be, in principle, any material used for this type of transfer sheet, and its thickness is usually preferably 5 to 200 μm, more preferably 12 μm.
~50 μm.

Specific examples include films of synthetic resins such as polyethylene terephthalate (so-called polyester), polypropylene, polyethylene, and polyamide, paper, and synthetic paper. These can be laminated and used if necessary.

The unevenness on the surface of the release sheet determines the unevenness on the surface of the protective layer when it is transferred. When it is desired that the surface after transfer be a mirror surface, the surface of these release sheets must be a mirror surface. In addition, in decorative applications, a matte surface is often required, so in that case, a matte film whose luster is adjusted by kneading a matting agent into a release sheet, sandblasting, or chemical etching, etc. It is better to use

The releasable sheet may be made of materials other than those mentioned above, or may be one in which a releasable layer is separately provided to make the surface releasable.

This releasable layer has a component that enables the protective layer to be peeled off from the base sheet of the transfer sheet during transfer, and specifically includes an appropriate vehicle (an example of a vehicle will be described later as a vehicle for a normal ink composition). (same as those used in the above) may be made alone or with the addition of a releasing substance such as wax or silicone as necessary.

Protective layer The protective layer is solid at room temperature in an uncured state, and
An ionizing radiation-curable resin that is thermoplastic and solvent soluble, yet provides a coating that is non-flowing and non-adhesive when applied and dried, even when touched by hand. It is formed as a material and is non-curable.

As such resins, there are the following two types of thermoplastic resins having radically polymerizable unsaturated groups.

(1) A polymer having a glass transition temperature of 0 to 250°C and having a radically polymerizable unsaturated group.

More specifically, compounds obtained by polymerizing or copolymerizing the following compounds 1 to 2 and introducing radically polymerizable unsaturated groups by methods (a) to (d) described below can be used.

■ Monomers with hydroxyl groups; N-methylol (meth)acrylamide, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2
-Hydroxybutyl (meth)acrylate, 2-hydroxy-3-phenoxyprobyl (meth)acrylate, etc.

■ Monomers having carboxyl groups; (meth)acrylic acid, (meth)acryloyloxyethyl monosuccinate, etc.

■ Monomer nigericidyl (meth)acrylate, etc. having an epoxy group.

(2) Monomers having an aziridinyl group = 2-aziridinylethyl (meth)acrylate, allyl 2-aziridinylpropionate, etc.

■ Monomers having amine groups: (meth)acrylamide, diacetone (meth)acrylamide, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, etc.

(2) Monomer having a sulfone group = 2-(meth)acrylamide-2-methylpropanesulfonic acid, etc.

■Single scene with incyanate group: adducts of diisocyanates and radically polymerizable monomers having active hydrogen, such as 1 mol to 1 mol adducts of 2,4-toluene diisocyanate and 2-hydroxyethyl (meth)acrylate, etc. .

■Furthermore, by adjusting the glass transition point of the above copolymer,
In order to adjust the physical properties of the cured film, the above compound can be copolymerized with the following monomers that can be copolymerized with this compound. Examples of such copolymerizable monomers include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, and t-butyl (meth)acrylate. ) acrylate, isoamyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and the like.

Next, the polymer obtained as described above is reacted by methods (a) to (d) described below to introduce a radically polymerizable unsaturated group, thereby obtaining an ionizing radiation-curable resin.

(a) In the case of a polymer or copolymer of a monomer having a hydroxyl group, a monomer having a carboxyl group such as (meth)acrylic acid is subjected to a condensation reaction.

(b) In the case of a polymer or copolymer of monomers having a carboxyl group or a sulfone group, the aforementioned monomers having a hydroxyl group are subjected to a condensation reaction.

(C) In the case of a single polymer or copolymer having an epoxy group, incyanate group or aziridinyl group, the above-mentioned monomer having a hydroxyl group or monomer having a carboxyl group is added.

(d) In the case of a polymer or copolymer of a monomer having a hydroxyl group or a carboxyl group, a monomer having an epoxy group or a monomer having an aziridinyl group or a diisocyanate compound and an acrylic acid containing a hydroxyl group. A 1:1 mole adduct of ester monomers is subjected to an addition reaction.

In order to carry out the above reaction, it is desirable to add V& amount of a polymerization inhibitor such as hydroquinone and carry out the reaction while blowing dry air.

(2) A compound having a melting point of room temperature (20°C) to 250°C and having a radically polymerizable unsaturated group. Specific examples include stearyl acrylate, stearyl (meth)acrylate, triacrylisocyanurate, cyclohexanediol diacrylate, cyclohexanediol di(meth)acrylate, spiroglycol diacrylate, and spiroglycol (meth)acrylate. In addition, in this invention, the above (1) and (2)
They can be used as a mixture, and a radically polymerizable unsaturated monomer can also be added to them. When irradiated with ionizing radiation, this radically polymerizable unsaturated monomer
It improves crosslinking density and heat resistance, and in addition to the above-mentioned monomers, it also contains ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, hexanediol di(meth)acrylate, and trimethylol. Propane tri(meth)acrylate, trimethylolpropane di(meth)acrylate, pentaerythritol tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ethylene glycol diglycidyl ether di(meth)acrylate Acrylate, polyethylene glycol diglycidyl ether di(
meth)acrylate, propylene glycol diglycidyl ether di(meth)acrylate, polybrobylene glycol diglycidyl ether di(meth)acrylate, solpitol tetraglycidyl ether tetra(meth)acrylate, etc. can be used. 0.1 to 10 parts by weight per 100 parts by weight of solids in the combined mixture
It is preferable to use 0 parts by weight.Although the above-mentioned materials can be sufficiently cured by ionizing radiation, when curing by ultraviolet irradiation, benzoquinone, benzoin, benzoin methyl ether, and natobenzoin are used as sensitizers. Ethers, halogenated acetophenones, biacetyls, and the like that generate radicals when irradiated with ultraviolet rays can also be used.

Half-cured The protective layer made of the above material is half-cured in the invention of this application.

Here, half-cure refers to a state in which the curable layer has not completed its reaction, and in the case of ultraviolet curable resins, some of the photoinitiator has been cleaved and has already reacted, but in the uncleaved state. Indicates that the initiator remains.

The degree of half-cure refers to the degree to which the performance can be dramatically improved by subsequent irradiation with ionizing radiation, and a relatively low degree of curing is sufficient. When it is completely cured by passing it 10 times at 5 m/min, and no abnormality is obtained by rubbing it with methyl ethyl ketone 200 times, when it is passed once under the same high-pressure mercury lamp at 30 m/min. This is the degree of hardening obtained, and in this case,
After rubbing with methyl ethyl ketone 10 times, the film only begins to dissolve.

Alternatively, the degree of Burfkinia is determined in consideration of the required performance.

For example, if a paint with an uncured glass transition point of 50°C is used and the heat applied during transfer is 70°C, the protective layer will melt and flow due to the heat during transfer, causing the glass to melt. It is possible to prevent flow by hardening the material to such an extent that the dislocation point reaches 80°C. In this way, the cured state of the protective layer on the transfer sheet can be determined between uncured and completely cured so as to maintain sufficient heat resistance at the temperature applied to the transfer sheet during use.

The irradiation dose required for this barfkinia can be set arbitrarily depending on the operating temperature of the transfer sheet, and is preferably 1 to 80%, more preferably 1 to 50% of the irradiation dose required for complete curing.
It is.

The ionizing radiation used for half-curing and for completely curing the protective layer after transfer is not particularly limited, and ultraviolet rays obtained from a high-pressure mercury lamp, metal halide lamp, xenon lamp, or low-pressure mercury lamp, or tungsten filament, etc. An electron beam pair obtained from an electron beam source such as a curtain type accelerator or a scanning type accelerator can be used.

In addition, the ionizing radiation irradiation when performing half-cure is
It can be applied either from the side of the release sheet or from the opposite side, but if the release sheet is colored or opaque and when using ultraviolet rays, irradiate from the side opposite to the release sheet. It is better.

In addition, the irradiation with ultraviolet rays or electron beams during complete curing is preferably carried out from the side opposite to the releasable sheet from the viewpoint of effective use of energy.

Metal thin film layer A layer to give a metallic appearance to the surface of the transferred object.The materials for making the metal thin film layer include aluminum, chromium, tin, silver, copper, and gold.
There are about 600 people. The metal thin film layer can be patterned if necessary, for example, a method in which a water-soluble pattern is provided, a metal thin film is provided, and then water is applied;
After a metal thin film is first provided, a resist pattern is provided, and then an acid or alkali is applied to form a pattern.

Pattern Layer The pattern layer is for imparting a pattern to the object to be transferred by transfer, and is not necessarily necessary.

By providing a pattern layer between the protective layer and the metal thin film layer, an even more beautiful appearance can be obtained.

Further, when the metal thin film layer is partially provided, the pattern layer may be arranged so that the pattern layer is visible in the areas where the metal thin film layer is not provided.

The pattern layer is usually provided directly on the protective layer or indirectly through another layer, and the type of ink may be determined in consideration of the intended use and the structure of the transfer sheet. Ordinary inks are prepared by kneading a vehicle with colorants such as pigments or dyes, plasticizers, stabilizers, other additives, or solvents or diluents.

Among the components of the ink, binders related to adhesion include homopolymers of acrylic or methacrylic monomers, such as polymethyl methacrylate, polyethyl methacrylate, di-methyl polyacrylate, and butyl polyacrylate, or copolymers of these monomers. Copolymers containing monomers, styrene resins such as polystyrene and poly-α-styrene, styrene copolymer resins, cellulose acetate, vinyl chloride, polyester resins, and preferably one or more alcohol-insoluble resins are selected and used. do.

These resins are diluted as necessary to obtain a viscosity suitable for coating, and then coated using known coating methods such as Eva, reverse roll coating, roll coating, gravure coating, kiss coating, blade coating, etc.
Coat with smooth coach-in, etc.

In the transfer sheet of the present invention, the method for providing other layers is generally the same, except that a printing method is used when providing the layers in a pattern.

The structure of the transfer sheet is basically as described above,
Furthermore, the following layers can be provided as necessary.

Layer of solvent-vaporable resin Prior to providing a layer in direct contact with the protective layer, for example, a metal thin film layer, a layer of solvent-vaporable resin such as a thermoplastic resin may be provided between the curable layer and the protective layer. good.

As the solvent volatilization type resin, it is preferable to select one that has good adhesion to the next layer of metal thin film.

Adhesive layer The adhesive layer is used to improve the adhesion between the metal thin film layer (or other added layers) and the object to be transferred. Any known material can be used.

Transfer method The transfer sheet of the present invention is transferred onto an object to be transferred by an appropriate method, and then irradiated with ionizing radiation to completely cure the transferred protective layer, thereby forming a completely cured film on the surface of the object to be transferred. can be made. At this time, there are cases where the release sheet is peeled off before irradiation, and cases where the release sheet is peeled off after irradiation.

Transfer methods include, for example: (1) Thermal transfer, in which a metal thin film layer (or other layers layered on top of the metal thin film layer in some cases) is thermocompression-bonded to the object to be transferred by heating, and the transfer is performed together with a protective layer. (1) A solvent activated transfer method in which an activating liquid consisting of a solvent or a resin solvent solution is interposed between the transfer sheet and the object to be transferred.1. (2) An example is a simultaneous molding transfer method in which a transfer sheet is placed in a mold during injection molding, and the transfer is performed simultaneously with molding using the heat and pressure of the injected resin.

Object to be Transferred Various objects can be used as objects to be transferred when performing transfer using the transfer sheet having a curable protective layer of the present invention, such as the following.

0 paper used for decorative material base materials, such as bleached kraft paper, titanium paper, linter paper, paperboard, gypsum board paper, etc.
■Plastic films, such as polyethylene film, polypropylene film, polyvinyl chloride film, polyhynyritene chloride film, polyvinyl alcohol film, polyethylene terephthalate film, polycarbonate film, nylon film, polystyrene film, ethylene vinyl acetate copolymer film, ethylene vinyl Alcohol copolymer film, ionomer, etc., ■Wood base materials, e.g., wood, plywood, particle board, etc.; ■Gypsum base materials, e.g., gypsum board, gypsum slag board, etc.; ■Fiber cement board, e.g., pulp cement board, Asbestos cement board, wood chip cement board, etc.; Other, GRC and concrete, metal foils or sheets such as iron, aluminum, copper, etc., and composites of each of the above materials.

Alternatively, various molded products can also be used as the transfer target, and examples of the materials for the molded product include the following materials, which overlap with the above-mentioned decorative material base materials.

AAS resin, ABS resin, AC3 resin, amino resin, cellulose resin such as cellulose acetate, cellulose butyrate, ethyl cellulose, allyl resin, ethylene-α-olefin copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl chloride Copolymer, ionomer resin, MB
S resin, methacrylic-styrene copolymer, nitrile resin, phenol resin, polyamide resin, polyarylate resin, polycarbonate resin, polybutadiene resin, polybutylene terephthalate resin, polyethylene resin, polyethylene terephthalate resin, polymethyl methacrylate resin, polypropylene resin, polyphenylene Plastic molded products such as oxide resin, polystyrene resin, AS resin, polyurethane resin, polyvinyl chloride resin, acrylic modified polyvinyl chloride resin, and unsaturated polyester resin.

Extrusion molded products of metals such as iron, aluminum, copper, and stainless steel.

Among the above methods, there is a method of transferring to a plastic molded product that has already been molded, and there is also the above-mentioned molding simultaneous transfer method of transferring the image when manufacturing the molded product.

If necessary, the transfer surface of the transfer object may be subjected to pretreatment depending on the material of the transfer object surface, such as pretreatment for adhesiveness such as primer treatment and corona treatment, painting, etc. These include adjusting the base color by using chlorine, sealing, and preventing alkali leaching from alkaline base materials such as cement.

〔Effect of the invention〕

According to this invention, since the protective layer on the transfer sheet is half-cured, it has higher heat resistance than an uncured state.
The heat applied during transfer can prevent the protective layer from flowing or unnecessarily deforming. Therefore, the transfer can be performed without affecting the metal thin film layer, so the gloss of the metal thin film layer after transfer can be improved. It never declines.

Furthermore, the protective layer can be completely cured by irradiation with ionizing radiation after the transfer.

〔Example〕

A polyester film (manufactured by Sunko ■, Russart, thickness 25 μm) was used as the release film, and on one side of the film was diluted with methyl ethyl ketone a melamine acrylate ultraviolet curable resin (manufactured by Mitsubishi Yuka ■, trade name: Yupima LZ-07' 5). The coated material was coated with gravure coating, dried with hot air at 100℃, and the film was solidified (
(coating thickness: 6 μm), followed by a solvent-intercalated resin layer.
A urethane resin paint (manufactured by Showa Ink ■) was coated using the gravure coating method so that the film had a thickness of 1 μm.

The polyester film coated with two layers was heated at a speed of 30 m/min using a high-pressure mercury lamp (160 w/c).
The ultraviolet rays were irradiated from the uncoated side to half-cure the film of the ultraviolet curable resin.

Next, aluminum was deposited to a thickness of 500 mm using a vacuum evaporation method.
The aluminum film was formed into a thin film, and then an acrylic heat-sensitive adhesive (Showa Ink (■)) was coated on the aluminum film to a thickness of 2 μm.

The obtained transfer sheet was transferred to an AS plate using a heated roller with a surface temperature of 200°C, and after transfer, the polyester film was peeled off.

Thereafter, the transferred surface of the AS plate was irradiated with ultraviolet rays for 5 seconds using a high-pressure mercury lamp (ozone lamp, 80 W/cm) to completely cure the protective layer.

The molded product thus obtained had an excellent metallic luster in the metal thin film layer, and was not scratched even when rubbed with steel wool: oooo.

For comparison, when a transfer sheet was used that was manufactured in the same manner as the transfer sheet used above, but the protective layer was left uncured without half-curing, the metallic luster disappeared after transfer.

Claims (3)

[Claims] (1) A lower layer is formed on the release surface of the release sheet after transfer, consisting of a half-cured curable layer of ionizing radiation-curable resin that is solid at room temperature in an uncured state and is thermoplastic. A transfer sheet comprising, in order, a protective layer for protection and at least a metal thin film layer. (2) The transfer sheet according to claim 1, further comprising a layer made of a thermoplastic resin between the curable layer and the metal thin film layer. (3) A transfer method comprising transferring onto the surface of an object to be transferred using the transfer sheet according to claim 1 or 2, and then irradiating ionizing radiation to crosslink and harden the transferred protective layer.