JP6554365B2 - Manufacturing method of exterior panel - Google Patents

Description

The present invention relates to a process for the production of exterior panel of a decorative layer formed by printing ink layer to the panel substrate can be fixed in a stable state.

  In portable electronic devices such as portable telephones and portable information terminals, an exterior panel provided with a frame-shaped light shielding area and a light transmitting area surrounded by the light shielding area is used.

  In the portable electronic device, the exterior panel appears on the front of the housing, and the display screen of the color display device provided inside the housing can be seen from the outside of the housing through the light transmission region. . In addition, a translucent touch sensor such as a capacitance type is disposed on the exterior panel. The touch sensor is provided with a detection region having a translucent electrode layer and a wiring layer extending from each electrode layer. The detection area is disposed to face the light transmission area, and the wiring layer is routed around the back of the light shielding area.

Patent Document 1 discloses a structure of a conventional exterior panel.
The exterior panel described in Patent Document 1 has an opening formed in a colored film, and the film is formed on the front and back surfaces of a base formed of a light-transmitting thermoplastic resin such as polycarbonate or acrylic. The part where the openings are formed is a light-transmitting area, and the part where the film is overlapped is a light-shielding area.

JP 2012-138594 A Japanese Unexamined Patent Publication No. 7-52522

  In the exterior panel shown in Patent Document 1, a resin film is overlaid on a base formed of a translucent resin to form a light shielding region, so the exterior panel becomes thicker in the light shielding region by the amount of overlapping of the film. , It will be difficult to pursue thinning of the exterior panel.

  Further, in the case where the light shielding area is formed of a colored resin film, there is no freedom in the design of the appearance of the light shielding area, and the color of the light shielding area is also limited.

  In the technical fields other than the manufacturing method of an exterior panel, the screen printing technique and the thermal transfer printing technique exist as a technique which forms a colored layer. However, when attempting to form a decorative layer to be the light shielding area by these printing techniques, it is also necessary to print the decorative layer on the resin film and then to superimpose the resin film on the translucent base. Similar to the conventional example described in Document 1, it is difficult to realize thinning of the exterior panel.

  Moreover, when it is going to print a decoration layer directly on the said translucent base, it is difficult to fix the decoration layer formed with the printing ink, and it becomes easy to produce the shift | offset | difference of printing, disorder of color, etc. For example, assuming that the decorative layer is directly transferred to the base using a thermal transfer printing technique, as described in Patent Document 2, in thermal transfer printing, an image with a coloring material is thermoplastically adhered. Since the adhesive layer is a layer that is soft and weak to temperature change, the decorative layer transferred to the base is easily deformed or peeled off, and a stable decorative layer is obtained. It becomes difficult to form.

The present invention provides a method for manufacturing an exterior panel that can form a decorative layer on a panel substrate using a thermal transfer printing technique, and can also expand the degree of freedom of the shape and color of the decorative layer. The purpose is that.

The present invention includes a panel substrate formed of a light-transmitting material, and in a method for manufacturing an exterior panel provided with a light-transmitting region and a light-blocking region,
(A) using a laminate in which a transfer release layer is laminated on a thermal transfer substrate, and in a thermal transfer step, transferring a printing ink layer to a part of the surface of the transfer release layer to form a decorative layer;
(B) superposing a thermosetting adhesive layer on the outer surface of the decorative layer and the outer surface of the transfer release layer in a region where the decorative layer is not formed;
(C) a step of surface bonding the outer surface of the thermosetting adhesive layer to a translucent panel substrate and curing the thermosetting adhesive layer by heat treatment to form a translucent thermosetting layer When,
(D) peeling the base material for thermal transfer from the transfer release layer after the step (b) or after the step (c), and leaving the transfer release layer as a cover resin layer ,
An area in which the decorative layer is formed is referred to as the light shielding area, and an area in which the decorative layer is not formed is referred to as the light transmitting area.

  The manufacturing method of the exterior panel of this invention uses the 2nd laminated body by which the said thermosetting adhesive layer was laminated | stacked on the peeling sheet in the process of said (b), The said thermosetting adhesive layer is said The outer surface of the decorative layer and the outer surface of the transfer release layer are surface-bonded to each other, and the heat-curable adhesive layer, the outer surface of the decorative layer, and the outer surface of the transfer release layer are preheated. Is preferably adhered.

  Moreover, the manufacturing method of the exterior panel of this invention peels off the said peeling sheet from the said thermosetting adhesive layer before the process of said (c), The said thermosetting adhesive layer is said panel by a hot press. It is preferable that the substrate be adhered and the thermosetting adhesive layer be thermally cured by the subsequent heat treatment.

In the method of manufacturing the exterior panel of the present invention, the decorative layer is formed on the inner surface of the thermosetting layer in the thermal transfer printing step, so that the decorative layer can be stably formed and fixed. Further, the decorative transfer layer can be formed with high dimensional accuracy by the thermal transfer printing process, and can be formed with various colors.

  Furthermore, the thermosetting adhesive layer for forming a thermosetting layer is heated by a preheating treatment to enhance the adhesiveness, whereby the outer surface of the decorative layer and the outer surface of the transfer release layer, and the panel substrate The thermosetting adhesive layer is allowed to adhere to the inner surface of the adhesive. By adopting this step, the thermosetting adhesive layer can be surely brought into close contact with the decorating layer, the transfer release layer, and the panel substrate and thermally cured.

An exploded perspective view showing an exterior panel, a touch sensor, and a display panel according to an embodiment of the present invention; Sectional drawing which cut the exterior panel shown in FIG. 1 by the II-II line | wire, (A) (B) (C) is process explanatory drawing which shows the manufacturing method of the exterior panel of embodiment of this invention, (A) (B) is process explanatory drawing which shows the manufacturing method of the exterior panel of embodiment of this invention, (A) (B) is process explanatory drawing which shows the manufacturing method of the exterior panel of embodiment of this invention,

  FIG. 1 shows an exterior panel 10, a touch sensor 1 and a display panel 2 according to an embodiment of the present invention.

  The exterior panel 10 constitutes a part of a case of a portable electronic device such as a mobile phone (smart phone), a portable information terminal device or a portable game machine, and appears on the front of the case. The touch sensor 1 is stacked on the inside of the exterior panel 10 directed inward of the device, and is bonded with an OCA (optically transparent adhesive). Further, the display panel 2 is built in the inside of the housing.

  The touch sensor 1 is a transparent resin substrate such as a PET film, in which a plurality of translucent electrode layers and a wiring layer connected to each electrode layer are formed, and the mutual capacitance change between the electrode layers Alternatively, an approach of a finger or the like is detected by a change in self-capacitance of each electrode layer.

  The display panel 2 is a color liquid crystal display panel or an EL (electroluminescence) display panel.

  As shown in FIGS. 1 and 2, the exterior panel 10 includes a light-transmitting region 10A and a frame-shaped light-shielding region 10B surrounding the light-transmitting region 10A. The display screen of the display panel 2 faces the light transmitting region 10A. The electrode layer of the touch sensor 1 faces the light transmitting region 10A, the wiring layer formed on the touch sensor 1 faces the inside of the light shielding region 10B, and the wiring layer can not be seen from the outside.

  The exterior panel 10 has a panel substrate 11. The panel substrate 11 is a translucent substrate as a whole, and is formed of flat glass. The panel substrate 11 may be formed of a translucent synthetic resin material such as polycarbonate or acrylic. In this case, the panel substrate 11 can have a shape having a curved surface.

  As shown in FIG. 2, the panel substrate 11 has an inner surface 11a facing inward of the apparatus and an outer surface 11b facing outward of the apparatus. A translucent thermosetting layer 12 is formed on the inner surface 11 a of the panel substrate 11. The thermosetting layer 12 is formed by thermosetting a thermosetting adhesive. The thermosetting adhesive is selected from polyester-based, acrylic-based, epoxy-based and the like, and polyester-based is preferable in order to improve the optical characteristics, that is, the total light transmittance.

  For example, the thermosetting adhesive is mainly composed of polyester obtained by condensation reaction of maleic anhydride and glycol, and contains isocyanate as a thermosetting reaction agent. This thermosetting adhesive is enhanced in tackiness by the preliminary heat treatment at about 50 to 70 ° C. to enhance the function as an adhesive, and thermally cured by the annealing treatment at about 90 to 110 ° C. to obtain unsaturated polyester It becomes the thermosetting layer 12.

  The thermosetting layer 12 is formed on the entire inner surface 11 a of the panel substrate 11. That is, the thermosetting layer 12 is formed on the inner surface 11a of the panel substrate 11 in both the light transmitting region 10A and the light shielding region 10B. The thermosetting layer 12 has an inner surface 12 a and an outer surface 12 b, and the outer surface 12 b is in close contact with the inner surface 11 a of the panel substrate 11.

  In the light shielding region 10 </ b> B, a decoration layer 13 is formed on the inner surface 12 a of the thermosetting layer 12. The decorative layer 13 is a printing ink layer formed in a thermal transfer process using a thermal transfer printer. At this time, the printing ink layer is formed of a thermoplastic resin. The decorative layer 13 formed of the printing ink layer transferred in the thermal transfer step can determine the overall shape and size with high accuracy, and can freely set the color and pattern. In the embodiment shown in FIGS. 1 and 2, the decorative layer 13 is formed in a frame shape surrounding the light transmitting area 10A, and the area where the decorative layer 13 is formed is the light shielding area 10B. The decorative layer 13 may be a printing ink layer formed by screen printing or the like.

  As shown in FIG. 2, a cover resin layer 14 is formed on the inner surface of both the light transmitting region 10A and the light shielding region 10B, and the inner surface 12a of the thermosetting layer 12 and the inner surface of the decorative layer 13 are formed. It is covered with a cover resin layer 14. The cover resin layer 14 is a thermoplastic resin layer and is formed of an acrylic resin. The cover resin layer 14 is a transfer peeling layer interposed between the thermal transfer substrate and the printing ink layer to be the decorative layer 13 when the decorative layer 13 is printed in the thermal transfer step.

  In the exterior panel 10 having the laminated structure shown in FIG. 2, the decorative layer 13 is formed of the printing ink layer, so the decorative layer 13 is thinner than in the conventional case where the decorative layer is formed of a resin film. This can contribute to the thinning of the exterior panel 10.

  Since a hard thermosetting layer 12 obtained by thermosetting a thermosetting adhesive layer (thermosetting resin layer) is formed between the decorative layer 13 and the panel substrate 11, it is formed of a thin printing ink layer Since the decorative layer 13 can be stably and firmly fixed and the hardness of the thermosetting layer 12 does not change even in a high temperature environment, the shape of the decorative layer 13 can be stabilized. In addition, since the decorative layer 13 is covered with the cover resin layer 14, the decorative layer 13 is protected, and problems such as separation of the decorative layer 13 in the manufacturing process are less likely to occur.

  Furthermore, in the light transmitting region 10A as well, since the thermosetting layer 12 and the cover resin layer 14 are formed on the inner surface 11a of the panel substrate 11, the inner surface 11a of the panel substrate 11 is protected. An external force does not act directly on the panel substrate 11, and it is possible to prevent the inner surface 11 a of the panel substrate 11 from being damaged.

Next, a method for manufacturing the exterior panel 10 will be described.
FIG. 3A shows the first stacked body 21. In the first laminate 21, a transfer release layer 14r is formed on a thermal transfer substrate 22. The thermal transfer substrate 22 is a resin film formed of a heat resistant resin such as PET (polyethylene terephthalate). The transfer peeling layer 14r is to be the cover resin layer 14 shown in FIG. 2 later, is a thermoplastic resin layer, and is formed of an acrylic resin.

  In the thermal transfer step using a thermal transfer printer, the decorative layer 13 is transferred onto the surface of the transfer release layer 14r. In the thermal transfer process, the first laminate 21 is placed on the platen of the thermal transfer printer, the thermal transfer ribbon is applied to the outer surface 14b of the transfer release layer 14r, and the printing ink layer on the surface of the thermal transfer ribbon is heated and melted by the thermal transfer head. It is transferred to the outer surface 14b.

  By using a thermal transfer printer, the shape and dimensions of the decorative layer 13 can be set with high accuracy. Further, it is possible to give a degree of freedom to the selection of the color and pattern of the decorative layer 13. It is also possible to overlap and form printing ink layers of different colors as the decorative layer 13, and for example, a black or chromatic upper ink layer is formed on a base ink layer such as white, and the upper ink layer is used. It is possible to form a deficient portion in the shape of a character or symbol representing the logo and expose the underlying ink layer to the logo portion.

  The thickness dimension of the transfer peeling layer 14r is about 5 to 15 μm, and the thickness dimension of the decoration layer 13 is about 5 to 15 μm. Preferably, the thickness dimensions of both the transfer peeling layer 14r and the decoration layer 13 are 10 μm. is there.

  The 2nd laminated body 25 is shown by FIG. 3 (A). The second laminate 25 is obtained by laminating the thermosetting adhesive layer 12 h on the release sheet 26. As described above, the thermosetting adhesive layer 12 h is mainly composed of polyester and contains isocyanate as a thermosetting reaction agent, and becomes a thermosetting layer 12 shown in FIG. 2 after thermosetting. The thickness dimension of the thermosetting adhesive layer 12h is about 10 to 40 μm, for example, 25 μm.

  In the preheating step shown in FIG. 3 (B), the transfer peeling layer 14r and the decoration layer 13 are made to face the thermosetting adhesive layer 12h to form the first laminate 21 and the second laminate 25. The two laminates 21 and 25 are sandwiched between the heating and pressure rollers 31 and 32, and are heated and pressurized. At this time, the preheating temperature is about 50 to 70 ° C., preferably 60 ° C. At this temperature, the thermosetting of the thermosetting adhesive layer 12 h does not proceed, and the thermosetting adhesive layer 12 h is Tackiness (tackiness) is enhanced. The thermosetting adhesive layer 12h is adhered to the transfer peeling layer 14r and the decorative layer 13 by the enhancement of the tackiness and the pressure between the rollers, and the first laminate 21 and the second laminate 25 are adhered. It joins and the 3rd laminated body 28 shown in FIG.3 (C) is formed.

  The third stacked body 28 shown in FIG. 3C is stored as it is, transported, or moved at a work place, and supplied to the bonding step with the panel substrate 11.

  In the bonding step of the panel substrate 11 and the third laminate 28, as shown in FIG. 4A, the release sheet 26 is peeled off, and as shown in FIG. 4B, the thermosetting adhesive layer 12h. Is superimposed on the inner surface 11 a of the panel substrate 11. Here, a hot stamp process, that is, a hot press process is performed, and the laminate from which the release sheet 26 has been removed and the panel substrate 11 are heated and pressurized. At this time, the thermosetting adhesive layer 12 h is heated to about 50 to 70 ° C., which is the same as the preheating temperature, and the tackiness of the thermosetting adhesive layer 12 h is enhanced, and the thermosetting adhesive layer 12 h and the panel are Adhesive bonding is performed with the substrate 11 by adhesion.

  Thereafter, the thermosetting adhesive layer 12 h is thermally cured by the heat treatment using the heating furnace 33 shown in FIG. 5B to form the thermosetting layer 12, and the decorative layer 13 is made of the hard thermosetting layer 12. Can be fixed on the inner surface of the

  After the thermosetting adhesive layer 12 h is thermally cured to form the thermosetting layer 12, the thermal transfer substrate 22 is peeled from the thermosetting layer 12 as shown in FIG. 5A.

  Alternatively, after the thermosetting adhesive layer 12h is overlaid on the outer surface of the transfer release layer 14r in the process of FIG. 3C, the thermal transfer substrate 22 may be removed, and then the process may proceed to the heat curing process. .

  In this manufacturing method, in the steps of FIGS. 3A, 3B and 3C, the thermosetting adhesive layer 12h is overlapped on both the surface of the decorative layer 13 and the outer surface 14b of the transfer peeling layer 14r. Since the curable adhesive layer 12 h is thermally cured, as shown in FIG. 2, the thermosetting layer 12 is formed on the inner surface 11 a of the panel substrate 11 in both the transmission region 10 A and the light shielding region 10 B. It is possible to increase the strength of the entire area on the inner surface side of the panel substrate 11.

DESCRIPTION OF SYMBOLS 1 Touch sensor 2 Display panel 10 Exterior panel 10A Translucent area | region 10B Light-shielding area | region 11 Panel board | substrate 11a Inner surface 11b Outer surface 12 Thermosetting layer 12h Thermoplastic adhesive layer 13 Decorating layer 14 Cover resin layer 14r Transfer peeling layer 21 1st Laminated body 22 Transfer base material 25 Second laminated body 26 Release sheet 28 Third laminated bodies 31 and 32 Heating / pressurizing roller 33 Heating furnace

Claims (3)

In a method for manufacturing an exterior panel having a panel substrate formed of a light-transmitting material and provided with a light-transmitting region and a light-blocking region,
(A) using a laminate in which a transfer release layer is laminated on a thermal transfer substrate, and in a thermal transfer step, transferring a printing ink layer to a part of the surface of the transfer release layer to form a decorative layer;
(B) superposing a thermosetting adhesive layer on the outer surface of the decorative layer and the outer surface of the transfer release layer in a region where the decorative layer is not formed;
(C) a step of surface bonding the outer surface of the thermosetting adhesive layer to a translucent panel substrate and curing the thermosetting adhesive layer by heat treatment to form a translucent thermosetting layer When,
(D) peeling the base material for thermal transfer from the transfer release layer after the step (b) or after the step (c), and leaving the transfer release layer as a cover resin layer ,
The manufacturing method of the exterior panel characterized by making the area | region in which the said decoration layer is formed the said light shielding area, and making the area | region in which the said decoration layer is not formed the said light transmission area. In the step (b), a second laminate in which the thermosetting adhesive layer is laminated on a release sheet is used, and the thermosetting adhesive layer is separated from the outer surface of the decorative layer and the transfer peeling The exterior panel according to claim 1 , wherein the exterior panel is bonded to the outer surface of the layer, and the thermosetting adhesive layer, the outer surface of the decorative layer, and the outer surface of the transfer release layer are adhered by preheating treatment. Manufacturing method. Before the step (c), the release sheet is peeled off from the thermosetting adhesive layer, and the thermosetting adhesive layer is adhered to the panel substrate with a hot press, and the heat treatment is performed thereafter. The manufacturing method of the exterior panel of Claim 2 which thermosets a thermosetting adhesive bond layer.

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