JP4459610B2 - Method for producing decorative sheet and method for producing simultaneously decorated decorative molded product - Google Patents

Description

  The present invention relates to a decorative sheet provided with a cholesteric liquid crystal layer having ultraviolet curable properties, a method for manufacturing the decorative sheet, and a method for manufacturing a molded simultaneous decorative molded product using the decorative sheet.

  Cholesteric liquid crystal thin film is known to change its visible color depending on temperature and to have a beautiful appearance with high brightness and spectral properties, but has low hardness and poor wear resistance and scratch resistance. .

  When such a cholesteric liquid crystal thin film is simultaneously decorated on the surface of a molded product such as home appliances, housing equipment, office equipment, and automobile parts, a protective layer of a thermosetting resin or an ultraviolet curable resin is provided on the base sheet. The decorative sheet which formed and formed the thin film of the cholesteric liquid crystal on it was used.

JP 2000-296700

  However, when a thermosetting resin is used as a protective layer and the thermosetting resin is thermoset by heating at the time of producing a decorative sheet, the problem is that the wear resistance and scratch resistance of the surface of the molded product are generally inferior. was there. On the other hand, when UV curable resin is used as a protective layer and UV curable resin is irradiated with UV light to produce a decorative sheet and UV curable resin is UV curable, the crosslink density of the resin is increased to improve wear resistance and scratch resistance. However, there is a problem that the protective layer becomes brittle and cracks are generated in the protective layer located on the curved surface of the molded product during the simultaneous decoration.

  Therefore, the present inventor has made the following invention in order to solve the above problems. That is, according to the first aspect of the present invention, a UV-curable semi-cured protective layer is formed on one surface of a UV-absorbing substrate sheet, and an UV-curable cholesteric liquid crystal layer is formed on the opposite surface. It is a decorative sheet.

  In the second aspect of the present invention, a semi-cured protective layer having ultraviolet curable properties is formed on one side of a substrate sheet having ultraviolet absorbing properties, and a cholesteric liquid crystal layer having ultraviolet curable properties is formed on the opposite surface. The method for producing a decorative sheet is characterized in that ultraviolet rays are irradiated from the cholesteric liquid crystal layer side to cure only the cholesteric liquid crystal layer with ultraviolet rays.

  The third aspect of the present invention is that the decorative sheet is placed in an injection mold, clamped, injected with a molding resin, cooled and solidified, and opened to obtain a molded product. This is a method for producing a molded and simultaneously decorated molded product, wherein the protective layer surface is irradiated with ultraviolet rays to cure the protective layer with ultraviolet rays.

  The decorative sheet of the present invention has the effect of forming a cholesteric liquid crystal layer having both a beautiful appearance and high wear resistance and scratch resistance on the surface of the molded product without cracking during the simultaneous molding. Moreover, the manufacturing method of the decorating sheet of this invention has the effect that the said decorating sheet can be obtained easily. In addition, the method for producing a simultaneously molded decorative molded product according to the present invention can easily provide a molded simultaneous decorated molded product having a cholesteric liquid crystal layer having both a beautiful appearance and high wear resistance and scratch resistance. effective.

  Hereinafter, an example of the invention of the decorative sheet of the present invention will be described. The decorative sheet 1 of the present invention has a UV-curable semi-cured protective layer 32 formed on one side of a UV-absorbing substrate sheet 30 and an UV-curable cholesteric liquid crystal layer 34 and The adhesive layers 35 are sequentially laminated (see FIG. 1).

  After adhering to the molding resin 2, a protective layer 32 is formed on the outermost surface, and a base sheet 30 containing an ultraviolet absorber, a cholesteric liquid crystal layer 34, and an adhesive layer 35 are sequentially laminated and molded. A molded product 4 is obtained (see FIG. 3). In addition, when the cholesteric liquid crystal layer 34 has adhesiveness, the adhesive layer 35 may be omitted.

  Further, the base sheet 30 having ultraviolet absorptivity referred to in the present invention is not only the case where the base sheet 30 itself has ultraviolet absorptivity by containing an ultraviolet absorber in the base sheet 30, but also one side or both sides of the base sheet 30. This also includes the case where the ultraviolet absorbing layer 33 is provided (see FIG. 1). Moreover, the case where the base sheet 30 contains an ultraviolet absorber and the ultraviolet absorbing layer 33 is provided is also included.

  For example, when the compatibility of the material of the ultraviolet absorbent and the base sheet 30 is poor and the ultraviolet absorbent is not uniformly dispersed in the base sheet 30, the amount of the ultraviolet absorbent contained in the base sheet 30 is very small or not at all. There is a case where the base sheet 30 is provided with the ultraviolet absorbing layer 33 on the surface of the base sheet 30 so as not to be contained, thereby obtaining the base sheet 30 having ultraviolet absorbing ability.

  The material of the base sheet 30 is polypropylene resin, polyethylene resin, polyamide resin, polyester resin, acrylic resin, polyvinyl chloride resin, polycarbonate resin, polyurethane resin, polystyrene resin, acetate resin, polyamide A resin sheet such as a resin and a sheet in which these are combined are preferable.

  The film thickness of the base sheet 30 is preferably 5 μm to 5 mm. This is because if the film thickness is less than 5 μm, there is a problem that the sheet is not rigid and the UV curable protective layer 32 cannot be supported, and if it is thicker than 5 mm, the sheet is too rigid and difficult to handle.

  The formation method of the base sheet 30 may be a general film forming method such as extrusion molding, calendar molding, or casting. The base sheet 30 may be subjected to easy adhesion treatment such as corona discharge treatment, plasma treatment, and easy adhesion primer coating on the surface as necessary.

  The base sheet 30 is preferably adjusted to contain an ultraviolet absorber such as 2-hydroxybenzophenone, salicylate, or cyanoacrylate so that the average light transmittance at least at a wavelength of 240 to 380 nm is less than 10%. It is because sufficient ultraviolet absorptivity cannot be obtained when the average light transmittance at a wavelength of 240 to 380 nm is 10% or more.

  When the ultraviolet absorbing layer 33 is formed on the surface of the base sheet 30, it is formed by various printing methods such as gravure, offset, and screen, and coating methods such as gravure coating, reverse coating, roll coating, comma coating, and lip coating. . Moreover, you may form by methods, such as painting and dipping.

  The film thickness of the ultraviolet absorbing layer 33 is preferably 0.5 μm to 50 μm. This is because when the film thickness is less than 0.5 μm, there is a problem that sufficient ultraviolet light absorption cannot be obtained, and when it is more than 50 μm, there is a problem that it is difficult to dry after printing.

  As a material of the protective layer 32, a material in which a photopolymerization initiator is blended with an ultraviolet curable resin such as an acrylic resin, a urethane resin, a polyester resin, or an epoxy resin as a main material, and a crosslinking agent is added. Can be mentioned.

  Examples of the photopolymerization initiator include azo-based polymerization initiators and photocationic polymerization initiators, and 0.5 to 5% by weight is preferably added to the ultraviolet curable resin. Examples of the crosslinking agent include heat-crosslinking type isocyanates, organic acid anhydrides, polyamines, and the like, and it is preferable to add 0.1 to 10% by weight to the ultraviolet curable resin.

  The protective layer 32 may be formed by various printing methods such as gravure, offset, and screen, and coating methods such as gravure coating, reverse coating, roll coating, comma coating, and lip coating. Also, methods such as painting and dipping may be used. After coating by these methods, it is preferable to carry out moderate heating to make it tack free.

  The method for making the protective layer 32 semi-cured is to partially introduce a functional group that causes a weak crosslinking reaction by heat into the ultraviolet curable monomer or oligomer forming the protective layer 32, and by adding a crosslinking agent and heating. There is a method of partially crosslinking monomers, oligomers, etc., but other methods may be used.

  Whether or not the protective layer 32 is in a semi-cured state is determined by the hardness of the surface of the protective layer 32. And the semi-hardened state as used in the field of this invention means the state which has not yet reached the hardness which should be originally obtained if it hardens | cures.

  The thickness of the protective layer 32 is preferably 0.5 μm to 50 μm. If the film thickness is less than 0.5 μm, there is a problem that sufficient peelability cannot be obtained, and if it is more than 50 μm, there is a problem that it is difficult to dry after printing.

  The material of the cholesteric liquid crystal layer 34 includes an ultraviolet curable resin such as an acrylic resin, a urethane resin, a polyester resin, and an epoxy resin, a microcapsule containing a cholesteric liquid crystal, and a photopolymerization initiator. Can be mentioned. The cholesteric liquid crystal layer 34 may be in an uncured state, a semi-cured state, or a fully cured state.

  Examples of the photopolymerization initiator include azo polymerization initiators and photocationic polymerization initiators, and it is preferable to add 0.5 to 5% by weight to the resin composition.

  The cholesteric liquid crystal layer 34 may be formed by various printing methods such as gravure, offset, and screen, and coating methods such as gravure coating, reverse coating, roll coating, comma coating, and lip coating. Also, methods such as painting and dipping may be used.

  The film thickness of the cholesteric liquid crystal layer 34 is preferably 0.5 μm to 50 μm. If the film thickness is less than 0.5 μm, there is a problem that sufficient brightness and a beautiful appearance cannot be obtained, and if it is more than 50 μm, there is a problem that it is difficult to dry after printing.

  The material of the adhesive layer 35 is acrylic resin, vinyl resin, urethane resin, polyester resin, polypropylene resin, polyethylene resin, polystyrene resin, polycarbonate resin, vinylon resin, acetate resin, polyamide resin. Resin can be mentioned, A preferable material is suitably selected according to adhesiveness with molding resin.

  The method for forming the adhesive layer 35 may be various printing methods such as gravure, offset, and screen, and coating methods such as gravure coating, reverse coating, roll coating, comma coating, and lip coating. Also, methods such as painting and dipping may be used.

  The film thickness of the adhesive layer 35 is preferably 0.5 μm to 10 μm. If the film thickness is less than 0.5 μm, there is a problem that sufficient adhesion cannot be obtained, and if it is more than 10 μm, there is a problem that it is difficult to dry after printing.

  In addition, you may provide the decoration layers 38, such as a grain pattern, a stone pattern, a cloth pattern, a character, a geometric pattern, a solid pattern, as needed. A plurality of decorative layers may be formed in parallel, or a metal film layer may be provided as necessary. In this case, the metal film layer may be entirely or patterned.

  Examples of the material of the decorative layer 38 include, but are not particularly limited to, polyester resins, acrylic resins, vinyl resins, nitrified cotton resins, urethane resins, and chlorinated rubber resins. In the case of a metal film layer, aluminum, chromium, copper, nickel, indium, tin, silicon oxide, and the like can be given, but there is no particular limitation. .

  The decoration layer 38 can be formed by gravure printing, offset printing, screen printing, or the like, or by coating, dipping, reverse coater, or the like. In the case of a metal film layer, there are methods such as vacuum deposition and plating.

  The film thickness of the decorative layer 38 is preferably 0.5 μm to 50 μm. When the film thickness is less than 0.5 μm, there is a problem that sufficient designability cannot be obtained, and when it is more than 50 μm, there is a problem that it is difficult to dry after printing. However, in the case of a metal film layer, 150 to 1200 mm is preferable. This is because if the film thickness is less than 150 mm, there is a problem that sufficient concealing property cannot be obtained, and if it is more than 1200 mm, there is a problem that cracks are likely to occur.

  Below, invention of the manufacturing method of the decorating sheet of this invention is demonstrated. In the method for producing a decorative sheet according to the present invention, a UV-curable semi-cured protective layer is formed on one side of an ultraviolet-absorbing base sheet, and an ultraviolet-curable cholesteric liquid crystal layer is formed on the opposite side. Thereafter, ultraviolet rays are irradiated from the cholesteric liquid crystal layer side to cure only the cholesteric liquid crystal layer (see FIG. 2).

  Normally, when creating a decorative sheet using a UV-curable cholesteric liquid crystal layer, UV irradiation to the decorative sheet is an essential condition in order to make the cholesteric liquid crystal layer tack-free. Since the protective layer which it has will also be hardened, there exists a problem that a crack enters at the time of shaping | molding simultaneous decoration.

  However, in the manufacturing method in which a base sheet having ultraviolet absorptivity is provided between the protective layer and the cholesteric liquid crystal layer as in the present invention, and the ultraviolet ray is irradiated from the cholesteric liquid crystal layer side, the irradiated ultraviolet ray is emitted from the cholesteric liquid crystal layer. Even if it passes through, it is almost absorbed by the base sheet having ultraviolet absorptivity and hardly reaches the protective layer.

  Accordingly, the film strength of the cholesteric liquid crystal layer is improved by being cured by ultraviolet rays, but since the protective layer is maintained in a semi-cured state, it is possible to prevent cracks from being formed at the time of simultaneous decoration.

The intensity of ultraviolet rays irradiated from the cholesteric liquid crystal layer side is preferably about 100 to 1000 mJ / m ² . Film strength of the weak and the cholesteric liquid crystal layer than the 100 mJ / m ² is insufficient, tends cholesteric liquid crystal layer is destroyed by the heat pressure of the molten injection molding resin, the stronger than 1000 mJ / m ^2, a portion of the ultraviolet light UV absorber This is because the protective layer is cured through the layer and cracks are likely to occur. In order to always ensure that the film strength of the cholesteric liquid crystal layer is sufficient and that some ultraviolet rays do not pass through the ultraviolet absorbing layer, the intensity of the ultraviolet rays irradiated from the cholesteric liquid crystal layer side is set to 200 to 500 mJ / preferably about m ^2.

  Next, the invention of the method for producing the simultaneously molded decorative molded product of the present invention will be described. The manufacturing method of the simultaneously decorated decorative molded product of the present invention is the method of installing the decorative sheet of the present invention in an injection mold, then clamping, injecting a molding resin, cooling and solidifying, and then opening the mold. The protective layer surface of the obtained molded product is irradiated with ultraviolet rays to cure the protective layer (see FIG. 3).

  That is, after obtaining a molded article by the simultaneous injection molding method, the protective layer surface of the molded article is irradiated with ultraviolet rays to cure the semi-cured protective layer. Therefore, the protective layer is in a semi-cured state at the time of injection molding and does not crack, and the protective layer is in a cured state at the time of completion of the simultaneous molding process, and the cured protective layer has high wear resistance and scratch resistance. The nature protects the cholesteric liquid crystal layer.

  The stronger the amount of ultraviolet rays applied to the surface of the protective layer of the molded article, the better as long as the material of each layer is not adversely affected.

  In the present invention, the case where the molded product is obtained by the simultaneous molding decoration method is shown, but the molded product is manufactured first, and the decorative sheet is pasted on the curved surface of the molded product. The same effect can be obtained by the same method.

  A protective layer made of an epoxy UV curable resin containing 1% by weight of polyamine is formed on one side of an acrylic film containing 1% of a cyanoacrylate UV absorber with a thickness of 5 μm by reverse coating. Then, warm air of 80 ° C. was applied for 120 seconds to make it a semi-cured state.

Next, a cholesteric liquid crystal ink composed of a microcapsule in which the cholesteric liquid crystal is confined on the opposite surface, an ultraviolet curable resin of an epoxy type, and a photopolymerization initiator is applied to the ultraviolet absorbing layer with a thickness of 1 μm by a reverse coating method. A liquid crystal layer was formed. Then, the cholesteric liquid crystal layer was ultraviolet-cured by irradiating the ultraviolet ray with 200 mJ / m ² from the surface on the cholesteric liquid crystal layer side.

Next, a vinyl chloride-based adhesive layer was formed on the cholesteric liquid crystal layer with a thickness of 1 μm by gravure printing. The decorative sheet obtained as described above was set in the cavity of an injection mold, the mold was fastened and filled with polystyrene resin, and after cooling, the mold was opened and the molded product was taken out. Then, the surface of the obtained molded product was irradiated with ultraviolet rays at 600 mJ / m ² to cure the protective layer with ultraviolet rays.

  A cholesteric liquid crystal layer having a beautiful appearance is formed on the surface of the simultaneously molded decorative molded product obtained, and its abrasion resistance cannot be removed by rubbing with a sand eraser, and its abrasion resistance is scratched with an H pencil. It was excellent that it was not damaged.

  An ultraviolet-ray absorbing layer made of an acrylic polyol-based resin containing 1% of a cyanoacrylate-based ultraviolet absorber is formed on one surface of a 125 μm-thick polypropylene film by gravure printing, and an epoxy-based epoxy resin containing 1% by weight of polyamine is formed thereon. A protective layer made of an ultraviolet curable resin was formed to a thickness of 8 μm by a reverse coating method, and a hot air at 80 ° C. was applied for 180 seconds to make it a semi-cured state.

  Subsequently, a cholesteric liquid crystal ink composed of a microcapsule in which cholesteric liquid crystal was confined on the opposite surface and an acrylic ultraviolet curable resin was applied in a thickness of 1 μm by a reverse coating method to form a cholesteric liquid crystal layer. Next, a vinyl chloride-based adhesive layer was formed on the cholesteric liquid crystal layer with a thickness of 1 μm by gravure printing.

Thereafter, the surface of the adhesive layer was irradiated with ultraviolet rays of 500 mJ / m ² to cure the cholesteric liquid crystal layer with ultraviolet rays. The decorative sheet obtained as described above was set in the cavity of an injection mold, the mold was fastened and filled with an acrylic resin, and after cooling, the mold was opened and the molded product was taken out. The surface of the molded product thus obtained was irradiated with ultraviolet rays of 1200 mJ / m ² to cure the protective layer with ultraviolet rays.

  A cholesteric liquid crystal layer having a beautiful appearance is formed on the surface of the simultaneously molded molded article thus obtained, and its abrasion resistance cannot be removed by rubbing with a sand eraser, and its abrasion resistance is scratched with a 2H pencil. Even though it was excellent, it was not damaged.

  The decorative sheet obtained by the present invention is used for decorating panel members and the like used for home appliances, housing equipment, office equipment, automobile parts and the like.

It is sectional drawing which shows an example of the decorating sheet which concerns on this invention. It is sectional drawing which shows one manufacture example of the decorating sheet which concerns on this invention. It is sectional drawing which shows one manufacture example of the shaping | molding simultaneous decoration molded product which concerns on this invention.

DESCRIPTION OF SYMBOLS 1 Decorating sheet 2 Molding resin 4 Molding simultaneous decorating molded product 30 Base sheet 32 Protective layer 33 Ultraviolet absorbing layer 34 Cholesteric liquid crystal layer 35 Adhesive layer 38 Decorating layer

Claims (2)

Forming a UV-curable protective layer on one side of the UV-absorbing base sheet having an average light transmittance of less than 10% at a wavelength of 240 to 380 nm;
Making the protective layer semi-cured;
Forming a cholesteric liquid crystal layer having ultraviolet curability on the opposite surface of the base sheet;
A process for producing a decorative sheet, comprising: irradiating the base sheet on which the protective layer and the cholesteric liquid crystal layer are formed with ultraviolet rays from the cholesteric liquid crystal layer side to cure only the cholesteric liquid crystal layer. Installing the decorative sheet produced by the method for producing a decorative sheet according to claim 1 in an injection mold;
The mold for injection molding is clamped, a molding resin is injected, and the molded product is formed by cooling and solidifying. At the same time, the decorative sheet is fixed to the surface of the molded product, the mold is opened, and the molded product is opened. Obtaining
And a step of irradiating the surface of the protective layer of the molded product with ultraviolet rays to cure the protective layer with ultraviolet rays.

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