JP2632343B2 - Transfer sheet having curable protective layer and transfer method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer sheet capable of forming a protective layer having excellent surface strength by transfer, and a transfer method using the transfer sheet.

[Conventional technology]

Attempts have been made to protect the pattern after transfer from abrasion and deterioration due to chemicals by forming a layer of the transfer sheet closest to the surface side after transfer using a curable resin as a material. In particular, when the protective layer is made of an ultraviolet curable resin or an electron beam curable resin, there is an advantage that curing can be performed instantly without the need for heat at the time of curing.

However, ordinary UV-curable resins and electron beam-curable resins are tacky in the uncured state, so it is difficult to provide the next layer after coating or printing. However, there was a problem in terms of adhesiveness when trying to provide a.

In addition, the obtained transfer sheet has a hardened protective layer and the rigidity of the entire transfer sheet is high, so that it can be transferred to a flat plate-shaped surface, but the protective layer is not easily deformed and has irregularities. It was difficult to transfer to the surface.

Therefore, an attempt has been made to provide a protective layer using an ionizing radiation-curable resin that is solid at room temperature in an uncured state. Such a resin can be dissolved in a solvent to provide a protective layer by coating and printing, and
The next layer can be applied and printed without having to irradiate ionizing radiation after providing the protective layer, and it has good adhesion and can be deformed like thermoplastic resin, so it can be transferred to uneven surfaces. Then, after transferring using the obtained transfer sheet, the protective layer is cured by irradiating with ionizing radiation, and the physical and chemical strength of the surface can be improved.

However, the protective layer as described above is uncured on the transfer sheet, and the heat resistance is as low as or lower than that of the thermoplastic resin.If the heat during transfer is too much, the protective layer melts and flows. In addition, there is a disadvantage that the metallic gloss of the metal thin film layer becomes dull as a result of affecting the metal thin film layer.

[Problems to be solved by the invention]

The object of the present invention is to solve the above-mentioned drawbacks when providing a protective layer by using "a resin which is solid at room temperature in an uncured state, and is thermoplastic and is ionizing radiation curable". is there.

[Means for solving the problem]

In the present invention, a protective layer is provided by using “an ionizing radiation-curable resin that is solid at room temperature in an uncured state and is thermoplastic,” and the protective layer is in a half-cured state. As a result, the above problem could be solved.

That is, the present invention is a method comprising: a release surface of a release sheet, which is solid at room temperature in an uncured state, and a curable layer obtained by half-curing a thermoplastic ionizing radiation-curable resin; A transfer sheet having a protective layer that protects the lower layer after transfer and at least a metal thin film layer ”as a gist, and“ Transfer to the surface of the flat to be transferred using the transfer sheet,
Thereafter, the transferred protective layer is cross-linked and cured by irradiating with ionizing radiation.

[Action]

According to this invention, since the protective layer of the transfer sheet has been half-cured in advance, the heat resistance is high, and the heat at the time of transfer melts and flows the protective layer, thereby affecting the metal thin film layer and affecting the metallic luster. Is prevented from being lost.

In addition, since the protective layer is not completely cured, it also has a transfer property to an uneven surface, so that the protective layer can be cured after the transfer.

[Specific Description of Configuration] The transfer sheet of the present invention is, at its simplest, made of three layers: a release sheet, a protective layer, and a metal thin film layer. Other structures of the transfer sheet will be described later.

Releasable sheet The material of the releasable sheet, in principle, may be any material used for this type of transfer sheet, and the thickness thereof is usually preferably 5 to 20 μm, more preferably 12 to 50 μm.
μm.

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

The irregularities on the surface of the release sheet determine the irregularities on the surface of the protective layer when transferred. When the surface after the transfer is desired to be a mirror (mirror) surface, the surface of these release sheets must be a mirror surface. In addition, in the case of decorative applications, a matte surface is often required. In this case, a matte film is used as a release sheet, in which the matting agent is kneaded, and the glossy state is adjusted by sandblasting or chemical etching. Good to do.

The release sheet may be made of a material other than the above-mentioned materials, or may be provided with a release layer separately to make the surface releasable.

The release layer has a component that enables the protective layer to be peeled off from the base sheet of the transfer sheet during transfer. Specifically, an appropriate vehicle (an example of a vehicle is a vehicle of a normal ink composition described later). It may be made by itself or, if necessary, by further adding a release material such as wax or silicone.

Protective layer Protective layer is solid at room temperature in the uncured state, and has thermoplasticity and solvent solubility, but is non-flowable by painting and drying or when touched by touch And a half-cured material made of an ionizing radiation-curable resin that gives a non-adhesive coating film.

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

(1) Those having a radical polymerizable unsaturated group in a polymer having a glass transition temperature of 0 to 250 ° C. More specifically, a compound obtained by polymerizing or copolymerizing the following compounds (1) to (4) with a radically polymerizable unsaturated group introduced by the methods (a) to (d) described below can be used.

A monomer having a hydroxyl group; N-methylol (meth) acrylamide, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2
-Hydroxybutyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate and the like.

Monomers having a carboxyl group: (meth) acrylic acid, (meth) acryloyloxyethyl monosuccinate and the like.

Monomers having an epoxy group: chrysidyl (meth) acrylate and the like.

Monomers having an aziridinyl group: 2-aziridinylethyl (meth) acrylate, allyl 2-aziridinylpropionate, and the like.

Monomer having an amino group: (meth) acrylamide,
Diacetone (meth) acrylamide, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate and the like.

Monomers having a sulfone group: 2- (meth) acrylamido-2-methylpropanesulfonic acid and the like.

Monomer having an isocyanate group: an adduct of a radical polymerizable monomer having an active hydrogen of diisocyanate, such as an adduct of 1,4-mol of 2,4-toluene diisocyanate and 2-hydroxyethyl (meth) acrylate.

Further, adjusting the glass transition point of the above copolymer,
In order to adjust the physical properties of the cured film, the above compound and the following monomers copolymerizable with this compound can be copolymerized. Such copolymerizable monomers include, for example, methyl (meth) acrylate,
Ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate,
Examples include isoamyl (meth) acrylate, cyclohexyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate.

Next, the polymer obtained as described above is reacted by the following methods (a) to (d) 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 a monomer having a carboxyl group or a sulfone group, the above-mentioned monomer having a hydroxyl group is subjected to a condensation reaction.

(C) In the case of a polymer or copolymer of a monomer having an epoxy group, an isocyanate group or an 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, a monomer having an aziridinyl group, or a diisocyanate compound and a hydroxyl group-containing acrylate monomer One to one mole of the adduct of the product is subjected to an addition reaction.

In order to carry out the above reaction, it is desirable to add a trace amount of a polymerization inhibitor such as hydroquinone and to carry out the reaction while sending 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, triacryl isocyanurate, cyclohexanediol diacrylate, cyclohexanediol di (meth) acrylate, spiroglycol diacrylate, spiroglycol (meth) acrylate, and the like. Further, in the present invention, the above (1) and (2) can be used as a mixture, and a radically polymerizable unsaturated monomer can be added thereto. This radically polymerizable unsaturated monomer increases the crosslinking density and improves heat resistance upon irradiation with ionizing radiation. In addition to the above-mentioned monomers, ethylene glycol di (meth) acrylate, polyethylene Glycol di (meth) acrylate, hexanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolpropane di (meth) acrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, di Pentaerythritol hexa (meth) acrylate, ethylene glycol diglycidyl ether di (meth) acrylate, polyethylene glycol diglycidyl ether di (meth) acrylate, propylene glycol diglycidyl ether (meth) Acrylate, polypropylene glycol diglycidyl ether di (meth) acrylate, sorbitol tetraglycidyl ether tetra (meth) acrylate, etc. can be used, and 0.1 to 100 parts by weight based on 100 parts by weight of the solid content of the copolymer mixture described above. It is preferable to use, and the above-mentioned compounds can be sufficiently cured by ionizing radiation, but when cured by irradiation with ultraviolet rays, benzoin ethers such as benzoquinone, benzoin, benzoin methyl ether, and the like, Those which generate radicals by ultraviolet irradiation, such as acetylated phenones and biacetyls, can also be used.

Half-Cure In the invention of this application, the protective layer made of the above material is half-cured.

Here, half-curing refers to a state in which the curable layer has not completed the reaction, and in the case of an ultraviolet curable resin, some photoinitiators have been cleaved and have already reacted, but are in an uncleaved state. This shows a state in which the initiator remains.

The degree of half-cure refers to the degree to which the performance can be improved by flight after irradiation with ionizing radiation.A relatively low degree of curing may be used.For example, under a high-pressure mercury lamp of 80 W / cm, the transfer speed is 5 m. It is completely cured by passing 10 times under the conditions of / min, and when rubbing with methyl ethyl ketone 200 times gives no abnormality, it is obtained when passing once under the same high-pressure mercury lamp at 30 m / min. This is the degree of curing, and at this time, the film starts to dissolve after rubbing with methyl ethyl ketone 10 times.

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

For example, in the case of using a coating material having a glass transition point of 50 ° C. in an uncured state, if the heat applied at the time of transfer is 70 ° C., the protective layer melts and flows due to the heat at the time of transfer. The dislocation point is set to about 80 ° C. to cure and prevent flow. As described above, the cured state of the protective layer on the transfer sheet can be determined between the uncured state and the completely cured state so that sufficient heat resistance can be maintained at the temperature applied to the transfer sheet during use.

The irradiation dose required for the half cure can be arbitrarily set according to the use temperature of the transfer sheet, and is preferably 1 to 80%, more preferably 1 to 50% of the irradiation dose required for complete curing.

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

Irradiation with ionizing radiation when performing half-curing may be performed from either the releasable sheet side or the opposite side, but ultraviolet rays are used when the releasable sheet is colored or opaque. At this time, it is preferable to irradiate from the side opposite to the release sheet.

Irradiation with ultraviolet rays or electron beams at the time of complete curing is preferably performed from the side opposite to the release sheet from the viewpoint of effective use of energy.

Metal thin film layer This layer is to give a metallic appearance to the surface of the transfer target.Materials for forming the metal thin film layer include aluminum, chromium, tin, silver, copper, gold, and the like. ~ 6
It is about 00 °. If necessary, the metal thin film layer can be formed into a pattern, for example, a method of providing a metal thin film after providing a water-soluble pattern and then applying water, or a resist pattern after providing the metal thin film first. Is formed, and then a pattern is formed by a method of allowing an acid or an alkali to act.

Picture layer The picture layer is for giving a picture to a transferred body by transfer, and is not always necessary. By providing the picture layer between the protective layer and the metal film layer, an even more beautiful appearance can be obtained.

Further, when the metal thin film layer is partially provided, the picture layer may be arranged so that the picture layer can be seen in a portion where there is no metal thin film layer.

The picture layer is usually provided directly on the protective layer or indirectly via another layer, and the type of ink may be determined in consideration of the application and the structure of the transfer sheet. An ordinary ink is obtained by kneading a vehicle with a pigment or dye coloring agent, a plasticizer, a stabilizer, other additives, a solvent or a diluent, or the like.

Among the components of the ink, as a binder relating to adhesiveness, a homopolymer of acrylic or methacrylic monomer such as polymethyl methacrylate, polyethyl methacrylate, polyethyl acrylate, polybutyl acrylate or these monomers are used. Preferably, one or more alcohol-insoluble resins such as copolymers, styrene resins such as polystyrene and poly α-sterene, and styrene copolymer resins, cellulose acetate, vinyl chloride, and polyester resins are selected and used.

These resins are diluted as necessary to have a viscosity suitable for application, and then coated by a known coating method, for example, reverse roll coating, roll coating, gravure coating, kiss coating, blade coating, smooth coating, or the like.

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

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

Layer of solvent-evaporating type resin A layer directly in contact with the protective layer, for example, a layer of a solvent-evaporating type resin such as a thermoplastic resin is provided between the curable layer and a layer prior to providing a metal thin film layer. Is also good.

As the solvent-evaporating resin, it is preferable to select a resin having good adhesiveness to the metal thin film of the next layer.

Adhesive layer The adhesive layer is used to improve the adhesiveness between the metal thin film layer (or another layer added) and the transfer target. Generally, it is preferable to use a heat-sensitive adhesive. Can be used.

Transfer method The transfer sheet of the present invention is a film which is completely cured on the surface of the transfer object by transferring the image onto the transfer object by an appropriate method, and then completely irradiating ionizing radiation to completely cure the transferred protective layer. Can be made. At this time, there is a case where the release sheet is peeled off before irradiation and a case where it is peeled off after irradiation.

As a transfer method, for example, a thermal transfer method in which a metal thin film layer (in some cases, another layer provided further overlying the metal thin film layer) is thermocompression-bonded to an object to be transferred and transferred together with a protective layer. A solvent-activated transfer body, in which an activating liquid comprising a solvent or a solvent solution of a resin is interposed between the transfer sheet and the transfer-receiving body, and the transfer sheet is placed in a mold during injection molding. For example, a simultaneous molding transfer method in which transfer is performed simultaneously with molding by heat and pressure of an injection resin can be exemplified.

Transfer Target Various types of transfer targets can be used as a transfer target when performing transfer using the transfer sheet having the curable protective layer of the present invention, and examples thereof include the following.

Used as a base material for cosmetics. Paper, for example bleached kraft paper, titanium paper, linter paper, paperboard, gypsum board paper, etc., plastic films, for example, polyethylene film, polypropylene film, polyvinyl chloride film, polyvinylidene chloride earm, 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-based materials, such as wood, plywood, particle board, etc., gypsum-based materials, such as gypsum board ,
Gypsum slag board, etc., fiber cement board, for example, pulp cement board, gypsum cement board, wood chip cement board, etc., GRC and concrete, iron, aluminum, copper and other metal foil or sheet, and each of the above ~ Complex.

Alternatively, various molded products can be used as the transfer object, and the material of the molded product overlaps with the above-mentioned decorative material base material, but the following materials can be exemplified.

AAS resin, ABS resin, ACS 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, MBS resin, methacryl-styrene copolymer, nitrile resin, phenol resin, polyamide resin, polyarylate resin, polycarbonate resin, polybutadiene resin, polybutylene terephthalate resin, polyethylene resin, polyethylene terephthalate resin, Plastic molded products such as polymethyl methacrylate resin, polypropylene resin, polyphenylene oxide resin, polystyrene resin, As resin, polyurethane resin, polyvinyl chloride resin, acryl-modified polyvinyl chloride resin, and unsaturated polyester resin.

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

Among the above methods, there is a method of transferring to a molded plastic article in order to transfer to a molded plastic article, but there is also the above-mentioned simultaneous molding transfer method of transferring when manufacturing a molded article.

The transfer-receiving surface of these transfer-receiving bodies may be subjected to a pretreatment according to the material of the surface of the transfer-receiving body, if necessary.
Examples include pretreatment for adhesion proof such as primer treatment and corona treatment, base color adjustment treatment by painting and the like, sealing treatment, and alkali leaching prevention treatment for alkaline base materials such as cement.

〔The invention's effect〕

According to this invention, since the protective layer on the transfer sheet is half-cured, the heat resistance is higher than that of the uncured state, and the flow and unnecessary deformation of the protective layer due to the heat applied during transfer are reduced. Since the transfer can be performed without affecting the metal thin film layer, the gloss of the metal thin film layer after transfer does not decrease.

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

〔Example〕

A polyester film (Las Art, 25 μm thick, manufactured by Reiko Co., Ltd.) was used as a release film, and a melamine acrylate-based UV-curable resin (manufactured by Mitsubishi Yuka Co., Ltd., trade name: Yupimer LZ-075) was methyl ethyl ketone on one surface. Is coated with gravure coating and dried with hot air at 100 ° C. to solidify the film (coating thickness: 6 μm). Subsequently, a urethane-based resin paint (manufactured by Showa Ink Co., Ltd.) ) Was coated by a gravure coating method so that the thickness of the film became 1 μm.

The polyester film coated with two layers is passed under a high-pressure mercury lamp (160 W / cm, with ozone) at a speed of 30 m / min so that ultraviolet light is irradiated from the uncoated side, The UV curable resin film was half-cured.

Then, aluminum is deposited by vacuum evaporation to a thickness of 500
Then, an acrylic heat-sensitive adhesive Showa Ink Co., Ltd. was applied on the aluminum thin film to a thickness of 2 μm.

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

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

The molded product obtained in this manner had an excellent metallic luster of the metal thin film layer, and was not damaged when rubbed with steel wool # 0000.

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

Continuation of the front page (56) References JP-A-64-18698 (JP, A) JP-A-1-159652 (JP, A) JP-A-61-98599 (JP, A)

Claims (3)

(57) [Claims] An uncured, non-cured, room temperature, ionizing radiation curable resin that is thermoplastic and comprises a half-cured curable layer on the release surface of a release sheet. A transfer sheet having a protective layer for protecting a lower layer and at least a metal thin film layer in order. 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. The transfer method according to claim 1, wherein the transfer sheet is transferred to the surface of a transfer-receiving member by using the transfer sheet according to claim 1 and then irradiated with ionizing radiation to crosslink and cure the transferred protective layer. Method.