JP4264484B2 - Molded product manufacturing method - Google Patents

Description

  The present invention relates to a method for producing a molded article by vacuum forming using a transfer sheet that can be recorded by an oil-based ink jet method, and a transfer sheet used therefor.

  As a method of obtaining a resin molded product having excellent design properties, a method of vacuum forming a resin plate that has been printed in advance is known. (For example, patent document 1) As a method of forming those printing layers, well-known printing techniques, such as normal gravure printing, offset printing, silk screen printing, and inkjet printing, can be used. Among these, inkjet printing is a simple output method. , Printing quality, and low cost when printing in small lots.

  However, when printing directly on a resin plate before vacuum forming by ink jet, it is necessary to apply an ink jet image receiving layer on the surface of the resin plate, which is not preferable in terms of cost. In addition, in this method, the surface of the finally obtained molded product becomes a printing surface, so the surface is inferior in scratch resistance. Further, when the printing method is an ink jet method using aqueous ink, the surface of the obtained molded product is water resistant. It was inferior in nature.

In addition, a decorative sheet in which an image-receiving layer that can be recorded by a water-based inkjet method is provided on a base sheet and the surface of the recorded image-receiving layer has adhesiveness has been proposed, and a decorative material in which such a decorative sheet is laminated on a resin plate If the material is vacuum molded, the printed part of the molded product finally obtained is protected by the base sheet, and a molded product having excellent scratch resistance is obtained. (For example, Patent Document 2)
However, the decorative material prepared by this method has a structure in which the volatile solvent contained in the ink-jet ink is sandwiched between a resin plate and a base sheet that are not permeable to air, and therefore remains in the image receiving layer by heating during vacuum forming. In some cases, moisture or a volatile organic solvent component, which is an ink-jet ink component, foams at the interface between the resin plate and the base sheet, which is not a preferable production method when used for vacuum forming. Furthermore, in the case of using an ink jet system using water-based ink, the sheet may be peeled off due to moisture permeating from the edge portion of the interface between the resin plate and the decorative sheet of the final molded product, and the water resistance is not sufficient.

Japanese Examined Patent Publication No. 56-24568 JP 2002-241714 A

In view of the above problems, an object of the present invention is provided using recordable transfer sheet with an oily ink jet method, design property by vacuum forming, water resistance, how to produce a good molded article scratch resistance There is.

  In order to achieve the above-mentioned object, the present invention ejects ink in accordance with image information by an oil-based ink jet method onto an image receiving adhesive layer surface of a transfer sheet in which at least a protective layer and an image receiving adhesive layer are sequentially laminated on a base sheet. Forming a decorative material by heating and pressing the image-formed transfer sheet to thermally transfer the image-receiving adhesive layer to a resin plate, and vacuum-molding the decorative material to produce a molded product And a step of curing the protective layer by irradiating the molded product with ionizing radiation.

The transfer sheet used in the present onset Ming, at least the protective layer and the image receiving adhesive layer is releasably laminated sequentially on a substrate sheet, said image-receiving adhesive layer is printable with an oily ink jet method and heat bonded to the resin plate The transfer sheet is characterized in that the main component of the protective layer is a resin curable by irradiation with ionizing radiation.

  Further, the image receiving adhesive layer may have a vinyl chloride-vinyl acetate copolymer as a main component and the resin curable by ionizing radiation irradiation may be an acrylic-silica hybrid resin. Further, as the acrylic-silica hybrid resin, those having a silica component of 15 wt% or more and 60 wt% or less may be used, and the acrylic-silica hybrid resin has a glass transition point of 30 ° C. or higher before curing. A thing may be used.

With manufacturing how the present invention is excellent in printing quality can correspond small lot production, water resistance, molded products obtained with excellent scratch resistance.

Embodiments of the present invention will be described below.
The base sheet used in the present invention is a resin sheet that releasably supports the protective layer and the image receiving adhesive layer, and is peeled off after the image receiving adhesive layer is transferred to the resin plate. Various resin sheets can be used as the base sheet, and polyethylene, polypropylene, polybutene, ethylene propylene copolymer, ethylene-vinyl acetate copolymer, polyethylene terephthalate, acrylic, vinyl chloride, polycarbonate, polyamide, etc. can be used. is there. Particularly preferably, it is a base sheet mainly composed of polyethylene terephthalate, and may contain additives for the purpose of improving sheet physical properties. Further, the thickness of the base sheet is preferably 20 μm or more in terms of workability and proper surface for ink jet printing, and is preferably a waste material that is peeled and removed after the image-receiving adhesive layer is transferred. It is not a thing. Moreover, you may give a well-known release process, an antistatic process, etc. suitably to a base material sheet as needed.

The transfer sheet used in the present invention is provided with a protective layer on at least a part of the substrate sheet. The protective layer is composed of at least one layer and is cured by irradiation with ionizing radiation to exhibit high scratch resistance. In order to obtain the above scratch resistance, the protective layer transfer film may be irradiated with ionizing radiation immediately after coating the protective layer, or may be ionized from the back surface of the protective layer transfer film using a transparent substrate. You may irradiate a radiation and you may irradiate after transfer to a resin board. Irradiation with ionizing radiation at any time can cure the protective layer and obtain the desired scratch resistance, but it is most preferable to irradiate after transfer to the resin plate for the following reasons. That is, if the protective layer is cured before transfer, the thermal sensitivity of the protective layer is reduced during transfer to the resin plate, resulting in insufficient peeling from the substrate sheet, or the protective layer at the stage of the vacuum forming process. This is because it is difficult to stretch the transferred protective layer by vacuum forming.

  Examples of the resin constituting the protective layer include acrylic-silica hybrid resins that can be cured by ionizing radiation. In the acrylic-silica hybrid resin, the silica component is preferably 15 wt% or more and 60 wt% or less, more preferably 20 wt% or more and 30 wt% or less. Outside the above range, the film strength is lowered, and the function as a protective layer may be deteriorated. The acrylic-silica hybrid resin preferably has a glass transition point of 30 ° C. or higher before curing. If it is lower than 30 ° C., the surface of the protective layer is tacky, which is not preferable for producing a transfer sheet, and it becomes difficult to further laminate an image receiving adhesive layer. Furthermore, for the purpose of improving the toughness of the protective layer, various acrylate oligomers and prepolymers such as polyester acrylate, polyurethane acrylate, epoxy acrylate and silicone acrylate having acryloyl group and methacryloyl group, or styrene for polyene-thiol resin, etc. A monofunctional monomer such as polyfunctional monomer such as trimethylolpropane triacrylate may be added. However, most of these acrylates are limited to addition in a range that does not cause tackiness in the protective layer because the properties before curing are liquid or viscous substances.

  In addition to the ionizing radiation curable resin, a thermoplastic resin can be added. Examples of the thermoplastic resin include acrylic resins, vinyl acetate resins, epoxy resins, polyester resins, polycarbonate resins, butyral resins, gelatin, cellulose resins, polyamide resins, vinyl chloride resins, urethane resins. Examples thereof include resins. As other additives, ultraviolet absorbers, colored pigments, white pigments, extender pigments, fillers, antistatic agents, antioxidants, fluorescent brighteners, dyes and the like can be used as necessary. The thickness of the protective layer is preferably from 0.1 to 10 μm, more preferably from 0.5 to 5 μm. This is because if the amount is less than the above range, the scratch resistance performance of the protective layer is low, and if the range is exceeded, the cost increases.

  In addition to acetophenone photoinitiators that are general photoinitiators, photoinitiators of the ionizing radiation curable resin include thioxanthones such as 2,4-diethylthioxanthone and 2-chlorothioxanthone, and bis (2 , 4,6-trimethylbenzoyl) -phenylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, phosphorus compounds such as 4,4-bisdiethylaminobenzophenone, Michler ketones, benzyl, etc. Although it can be used, it is not limited to this. The addition amount of the photoinitiator is preferably about 0.1 to 10% by weight, more preferably 2 to 5% by weight with respect to the ionizing radiation curable resin.

  Moreover, it is also preferable to use the following sensitizers. For example, aliphatic amines, amines containing aromatic groups, amine compounds such as nitrogen heterocyclic compounds such as piperidine, urea compounds such as allyl, O-tolylthiourea, sodium diethyldithiophosphate, solubility of aromatic sulfinic acid Sulfur compounds such as salts, nitrile compounds such as N, N-disubstituted-P-aminobenzonitrile compounds, phosphorus compounds such as tri-n-butylphosphine and sodium diethyl phosphate, Michler's ketone, N-nitrosohydroxylamine derivatives And other nitrogen compounds such as oxazoline compounds, and chlorine compounds such as carbon tetrachloride and hexachloroethane. The addition amount of the sensitizer is preferably about 0.1 to 10% by weight, more preferably 2 to 5% by weight with respect to the ionizing radiation curable resin.

  When the protective layer is difficult to peel from the substrate, a release layer can be formed between the substrate sheet and the protective layer. The release layer includes, for example, waxes, silicone wax, silicone resin, fluorine resin, acrylic resin, polyvinyl alcohol resin, cellulose derivative resin, urethane resin, acetic acid vinyl resin, acrylic vinyl ether resin, maleic anhydride resin, and It can be formed by applying and drying a coating solution containing at least one of these resin groups by a conventionally known method such as gravure coating or gravure reverse coating. The release layer can be appropriately selected from those that transfer to the transfer material during thermal transfer, those that remain on the substrate sheet side, or those that cohesively break down, but the release layer is non-transferable and is released by thermal transfer. The mold layer remains on the base sheet side so that the interface between the release layer and the transfer protective layer becomes the surface of the protective layer after thermal transfer in terms of surface gloss, transfer stability of the protective layer, etc. It is preferable because of its superiority. The release layer can be formed by a conventionally known coating method, and it is sufficient that the coating amount is about 0.5 to 5.0 μm in a dry state. When a matte protective layer is desirable after transfer, the surface of the release layer is matted by incorporating various particles in the release layer or by matting the surface of the release layer on the protective layer side. You can also. In addition, if the peelability of a base material sheet and a protective layer is favorable, a protective layer can peel directly from a base material sheet by thermal transfer, without providing said release layer.

  The image receiving adhesive layer is a layer provided on the protective layer of the transfer sheet, and is characterized in that it can be printed by an oil-based ink jet method and has thermal adhesiveness to the resin plate. Here, as a component of the image receiving adhesive layer, it is desirable to contain 20 to 100% by weight of vinyl chloride-vinyl acetate copolymer. Since the image-receiving adhesive layer has a vinyl chloride-vinyl acetate copolymer as a main component, it is possible to obtain good adhesiveness to various thermoplastic resin materials such as ABS and acrylic, and furthermore, by an ink jet method using oil-based ink. Since printing is possible, it is possible to create a transfer sheet that takes advantage of print quality and low cost when printing in a small lot.

  In addition, the image receiving adhesive layer containing 20 to 100% by weight of vinyl chloride-vinyl acetate copolymer has good thermoformability, and the decorative material obtained by transferring the image receiving adhesive layer to the surface of the resin plate is vacuum molded. Shows excellent moldability without cracking or cracking in the image receiving adhesive layer. Further, the image receiving adhesive layer needs to substantially not exhibit adhesiveness in a room temperature environment. This is because when the transfer sheet is handled in the ink jet printing process, if the transfer sheet surface is sticky in a room temperature environment, the transfer sheet or the like that comes into contact with the transfer sheet surface may cause problems such as poor conveyance.

  As the vinyl chloride-vinyl acetate copolymer used for the image-receiving adhesive layer, one having a glass transition point so-called Tg of 40 ° C. or higher is used so that the transfer layer is not substantially tacky in a room temperature environment. It is desirable, but not limited to this. The vinyl chloride-vinyl acetate polymer composition ratio of the vinyl chloride-vinyl acetate copolymer used for the image-receiving adhesive layer is preferably in the range of 50:50 to 96: 4 of vinyl chloride: vinyl acetate. This is because if the composition ratio of vinyl chloride is higher than the above ratio, the adhesiveness is inferior, and if the composition ratio of vinyl chloride is lower than the above ratio, the recordability in the ink jet system using oil-based ink is inferior.

  In addition to the vinyl chloride-vinyl acetate copolymer, various resin materials, fine particles, ultraviolet ray inhibitors, antistatic agents, lubricants, and the like can be added to the image receiving adhesive layer. Specific examples of resins that can be added include acrylic resins, vinyl chloride resins, vinyl acetate resins, urethane resins, polyester resins, epoxy resins, ethylene-vinyl acetate copolymers, and polyamide resins. It is not limited. Examples of additives that can be added include silica, alumina, calcium carbonate, magnesium carbonate, aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, aluminum silicate, calcium silicate, zeolite, mica, carbon black, titanium white, and zinc. Flower, Petal, Bitumen, Cadmium Red, Azo pigment, Lake pigment, Anthraquinone pigment, Phthalocyanine pigment, Quinacridone pigment, Isoindolinone pigment, Imidazolone pigment, Dioxazine pigment, Gold powder, Silver powder, Copper powder, Aluminum powder, Fish scale powder, Pearl A pigment, a fluorescent pigment, a luminescent pigment, or a mixture of two or more selected from these pigments can be used.

  The thickness of the image receiving adhesive layer is not particularly limited, but is preferably 2 μm or more in order to ensure adhesion with the resin plate, and is preferably 100 μm or less in consideration of productivity.

  As the resin plate used in the present invention, a resin plate made of a thermoplastic resin that can be molded in a vacuum forming method can be used, and a resin plate made of various resin materials as mentioned in the material of the base sheet is used. Is possible. The thickness of the resin plate can be about 50 to 5000 μm, but is not particularly limited. Also, the resin plate may be subjected to a known easy adhesion treatment or antistatic treatment as in the case of the base sheet.

  A printing layer may be formed on the entire surface or a desired portion between the protective layer and the image receiving adhesive layer by a known printing method such as gravure printing, letterpress printing, offset printing, silk screen printing, transfer printing, or hand-drawing method. The pattern formed by printing is not particularly limited, such as wood grain, stone grain, cloth grain, sand grain, letters, symbols, and the like. The printing layer ink is mainly composed of a vehicle comprising a binder, a colorant, and an additive. The binder resin includes ethylene-vinyl acetate copolymer, acrylic resin, polyester resin, vinyl chloride resin, vinyl chloride-vinyl acetate. Copolymers, chlorinated polypropylene, epoxy resins, cellulose, urethane resins and the like can be used. Also, known pigments and dyes can be used as the colorant, such as carbon black, titanium white, zinc white, petal, bitumen, cadmium red, azo pigment, lake pigment, anthraquinone pigment, phthalocyanine pigment, quinacridone pigment, An isoindolinone pigment, imidazolone pigment, dioxazine pigment, gold powder, silver powder, copper powder, aluminum powder, fish scale powder, pearl pigment, fluorescent pigment, luminescent pigment, or a mixture of two or more selected from these can be used.

FIG. 1 is a schematic cross-sectional view showing the form of a transfer sheet used in the present invention. The transfer sheet 1 is obtained by sequentially laminating a protective layer 3 and an image receiving adhesive layer 4 on a base sheet 2 in a peelable manner. It is.
FIG. 2 is a schematic cross-sectional view showing the form of the decorative material of the present invention. The decorative material 6 is obtained by thermally transferring the protective layer 3 and the image-receiving adhesive layer 4 formed with an image to a resin plate 5.
FIG. 3 is a schematic cross-sectional view showing a state in which the decorative material 6 of the present invention is fixed by the fixing frame 9 and then set so as to face the surface of the mold 10 of the vacuum forming apparatus. A heater 7 is installed on the top of the decorative material 6.
FIG. 4 is a schematic cross-sectional view showing a state in which the cosmetic material 6 is vacuum-formed by the vacuum forming apparatus in FIG. 3. After the cosmetic material 6 is heated and softened by the heater 7, the pressure is reduced by the vacuum suction hole 8. 6 is formed along the surface of the mold 10.
Hereinafter, the present invention will be described in detail by way of examples and comparative examples.

The protective layer coating solution 1 was applied to the surface of a 25 μm PET film having a heat resistant slip treatment on the back surface with a bar coater so that the dry coating amount was 5 μm. Subsequently, the transfer sheet 1 was obtained by applying the image-receiving adhesive layer coating solution 1 on the protective layer with a bar coater so that the dry film thickness was 10 μm. Next, a pattern was formed on the surface of the image-receiving adhesive layer of the obtained transfer sheet by an ink jet method using an oil-based ink, and a transfer sheet 1 on which the pattern was formed was created. Further, the surface of the image-receiving adhesive layer of the transfer sheet 1 obtained is made to face the surface of a resin plate made of polymethyl methacrylate and having a thickness of 4 mm, and press-contacted with two rubber rolls heated to 130 ° C. The layer 1 was transferred to make a cosmetic material 1.
(Coating liquid for protective layer 1)
70 parts of UV curable acrylic silica hybrid resin (solid content 30%, silica component 23%, Tg 45 ° C., Mw 20,000)
Photoinitiator 1.0 parts (trade name; Irgacure 819, manufactured by Ciba Specialty Chemicals)
30 parts of methyl ethyl ketone
(Coating fluid for image-receiving adhesive layer 1)
20 parts of vinyl chloride-vinyl acetate copolymer (trade name: VAGH, manufactured by Union Carbide)
80 parts of methyl ethyl ketone

A decorative material 2 to which the protective layer and the image receiving adhesive layer were transferred was prepared in the same manner as in Example 1 except that the protective layer coating liquid 2 was used as the protective layer coating liquid in Example 1.
(Protective layer coating solution 2)
70 parts of UV curable acrylic silica hybrid resin (solid content 30%, silica component 20%, Tg 55 ° C., Mw 25,000)
Photoinitiator 1.0 part (trade name; Kayacure CTX, Nippon Kayaku)
30 parts of methyl ethyl ketone [Comparative Example 1] A coating solution prepared by dissolving 15 parts by weight of an acrylic ester resin in 85 parts by weight of water in an acrylic resin base sheet having a thickness of 75 μm is 10 μm when dried with a Mayer bar coater. A decorative sheet was prepared by applying and drying as described above. Next, after forming a pattern on the surface of the obtained decorative sheet by an aqueous ink jet method, the image receiving surface of the obtained decorative sheet is made to face the surface of a resin plate made of polymethyl methacrylate and having a thickness of 4 mm, and two rubber rolls are used. A decorative sheet 3 was laminated to prepare a decorative material 3.

  [Comparative Example 2] A coating solution prepared by dissolving 20 parts by weight of a vinyl chloride-vinyl acetate copolymer in 80 parts by weight of methyl ethyl ketone in an acrylic resin base sheet having a thickness of 75 μm is 10 μm when dried with a Mayer bar coater. A decorative sheet having an image receiving adhesive layer laminated thereon was prepared by coating and drying as described above. Next, after forming a pattern on the surface of the obtained decorative sheet by an oil-based ink jet method, the image receiving surface of the obtained decorative sheet is made to face the surface of a resin plate made of polymethyl methacrylate and having a thickness of 4 mm, and two rubber rolls are used. A decorative sheet 4 was laminated to prepare a decorative material 4.

  [Comparative Example 3] In Example 1, the image receiving adhesive layer was prepared in the same manner as in Example 1 except that the protective sheet was not provided and only the image receiving adhesive layer coating solution 1 was applied and dried to prepare the transfer sheet 3. The decorative material 5 to which was transferred was prepared.

(Inkjet recording suitability) The suitability of printing when printing on the surface of the image-receiving adhesive layer with an oil-based inkjet printer (trade name: JV-3 / Mimaki Engineering Co., Ltd.) was evaluated. However, Comparative Example 1 evaluated the recording suitability when printed with an aqueous inkjet printer (trade name: PX-7000 / manufactured by Epson).
○: Clear and high image quality.
(Triangle | delta): Although the ink spreads a little, the image quality which is satisfactory practically was obtained.
X: A clear image quality was not obtained.

(Vacuum formability) Formability when formed with a vacuum forming apparatus was evaluated.
○: Vacuum forming is possible without problems.
Δ: Bubbles may be generated by heating during molding.
X: Many bubbles are generated and there is no practicality.

(Water resistance) After the molded article was immersed in water for 24 hours, the deterioration of the pattern was evaluated.
○: No change in image quality.
X: The pattern completely peeled off.

(Scratch resistance) The surface of the vacuum-formed decorative board was evaluated by rubbing 10 times with steel wool (Bonster # 0000) applied with a load of 250 g / cm ² . In Examples 1 and 2, the surface of the decorative material formed by the vacuum forming apparatus is irradiated with UV light having an integrated light amount of 200 mj / cm ² by a conveyor-type UV irradiation apparatus (CS30 manufactured by GS) to form a protective layer. The cured product was evaluated.
○: No change.
X: Scratch size.

  The above evaluation results are as shown in Table 1 below.

It is a schematic cross section which shows the form of the transfer sheet 1 used by this invention. It is a schematic cross section which shows the form of the decorative material 6 of this invention. FIG. 2 is a schematic cross-sectional view showing a state in which the decorative material 6 of the present invention is fixed by a fixing frame 9 and then set so as to face the surface of a mold 10 of a vacuum forming apparatus. FIG. 4 is a schematic cross-sectional view showing a state in which the decorative material 6 is softened by heating with a heater 7 in FIG. 3, and then the pressure is reduced by a vacuum suction hole 8, and the decorative material 6 is molded along the surface of a mold 10.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Transfer sheet 2 ... Base material sheet 3 ... Protective layer 4 ... Image receiving adhesive layer 5 ... Resin board 6 ... Cosmetic material 7 ... Heater 8 ... Vacuum suction hole 9 ... Fixed frame 10 ... Mold

Claims (1)

An image is formed by ejecting ink according to image information by an oil-based ink jet method on the surface of the image receiving adhesive layer of the transfer sheet in which at least a protective layer and an image receiving adhesive layer are sequentially laminated on the base sheet, Heating and pressurizing the transfer sheet to thermally transfer the image receiving adhesive layer to a resin plate to create a decorative material, vacuum forming the decorative material to create a molded product, and ionizing radiation to the molded product And a step of curing the protective layer by irradiating the protective layer.

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