ADHESION METHOD FOR ADHERING GLASS COMPONENT AND RESIN COMPONENT

A glass component, which has a first surface and a second surface that faces in a direction opposite to the first surface, and a resin component are adhered. The first surface of the glass component and the resin component are caused to face each other and the glass component and the resin component are layered, the first surface of the glass component being provided with an acrylic ink printing. IR laser is radiated from the first surface of the glass component toward the printing, and the glass component and the resin component are welded by a heat of dissolution of the printing.

BACKGROUND

The present disclosure relates to adhesion technology and, more particularly, to an adhesion method for adhering a glass component and a resin component.

2. Description of the Related Art

The steps to manufacture a display involves various thermal processes. One of the processes is a process to adhering the front glass substrate and the rear glass substrate in an airtight manner. For example, a thin film that absorbs laser light is sandwiched between glass members to adhere the members. The thin film is irradiated by a laser light via a glass plate. This causes the two glass members sandwiching the thin film to be welded by the heat generated by the thin film (see, for example, patent literature 1).

The steps to manufacture a display involves a process to adhere a glass component and a resin component. For adhesion of a glass component and a resin component, adhesion by an adhesive agent for adhesion via a double-sided tape or an adhesive is widely used in the related art. However, the adhesion strength of adhesion by an adhesive agent is relatively small so that the adhesion area should be extended in order to increase the adhesion strength.

SUMMARY

The present disclosure addresses the issue described above, and a purpose thereof is to provide a technology for increasing the strength of adhesion between a glass component and a resin component.

An adhesion method according to an embodiment of the present disclosure is an adhesion method adapted to adhere a glass component, which has a first surface and a second surface that faces in a direction opposite to the first surface, and a resin component, the method including: causing the first surface of the glass component and the resin component to face each other and layering the glass component and the resin component, the first surface of the glass component being provided with an acrylic ink printing;

and radiating laser light from the second surface of the glass component toward the printing and welding the glass component and the resin component by a heat of dissolution of the printing.

DETAILED DESCRIPTION

Before describing the embodiment of the present disclosure in specific details, a summary of the embodiment will be described. The embodiment relates to an adhesion method for adhering a cover glass (glass component) and a case (resin component) in the steps to manufacture a display mounted on a vehicle. As described above, a glass component and a resin component are adhered by a double-sided tape or an adhesive agent in the related art, but the adhesion strength of adhesion by a double-sided tape, etc. is relatively small. Thus, an increase in adhesion strength necessitates an increase in adhesion area. Further, the related-art approach has disadvantages in that a double-sided tape need be sticked or an adhesive agent need be applied and so the adhesion steps are time-consuming and in that the number of components is increased because a double-sided tape or an adhesive agent is necessary other than the glass component and the resin component.

To increase the strength of adhesion of a glass component and a resin member, the glass component and the resin member are welded by laser welding via an ink according to the embodiment. If a condition to weld two glass members by laser welding is used, however, the temperature of the resin member will be so high that the resin member will be completely dissolved. If the component and the member are irradiated by laser insufficiently to prevent dissolving of the resin member, sufficient adhesion strength cannot be obtained. In this background, an acrylic ink is used in the embodiment.

The terms “parallel” and “orthogonal” in the following description not only encompass completely parallel or orthogonal but also encompass slightly off-parallel and slightly non-orthogonal within the margin of error. The term “substantially” means identical within certain limits.

A description will first be given of the structure of a display100according to the related art in which a double-sided tape is used.FIG.1is a cross-sectional view showing the structure of the display100according to a comparative example. The display100includes a glass component10, a liquid crystal component20, a backlight22, a resin component30, and a double-sided tape40. A user is located above the display100ofFIG.1, and the user is viewing a video displayed on the display100from above. A device on which the display100is mounted is provided beneath the display100ofFIG.1, and the device outputs a video signal to the display100. Therefore, denoting the side above the display100as “user side”, the side beneath the display100is denoted by “intra-device side”.

The glass component10is a glass cover and is referred to as a glass plate. The surface of the glass component10on the intra-device side is a first surface12, and the surface of the glass component10on the user side is a second surface14. The first surface12and the second surface14face in directions opposite to each other. When the glass component10is viewed from the user side, the glass component10has a rectangular shape, and a frame-shaped printing16is provided at the outer edge of the first surface12. The printing16has, for example, a black color.

A liquid crystal component20is provided in the central part of the first surface12of the glass component10that is not provided with the printing16. The liquid crystal component20includes a color filter, a liquid crystal, a transparent electrode, etc. The backlight22is provided on the intra-device side of the liquid crystal component20. By causing the backlight22to radiate a light from the intra-device side while a video is being displayed on the liquid crystal component20, the screen is lighted.

The resin component30has an opening in the central part of the surface on the user side, and the opening extends through the intra-device side to form a through hole. The glass component10can be mounted on the opening of the resin component30from the user side. Further, the liquid crystal component20and the backlight22are provided in the through hole. A double-sided tape40is sticked on the intra-device side of the printing16on the first surface12of the glass component10. Like the printing16, the double-sided tape40may have a frame shape. The intra-device side of the double-sided tape40is sticked to the resin component30. Consequently, the glass component10and the resin component30are adhered by the double-sided tape40.

Hereinafter, the adhesion method according to the embodiment is described in the sequence (1) layering step, (2) laser irradiation step. (1) Layering step

FIG.2is a cross-sectional view showing a step of manufacturing the display200. The display200includes a glass component210, a liquid crystal component220, a backlight222, and a resin component230. The display200, the glass component210, the liquid crystal component220, the backlight222, and the resin component230correspond to the display100, the glass component10, the liquid crystal component20, the backlight22, and the resin component30of

FIG.1, respectively. Denoting the side above the display200ofFIG.2as “user side”, the side beneath the display200is denoted by “intra-device side”.

The surface of the glass component210on the intra-device side is a first surface212, and the surface of the glass component210on the user side is a second surface214. The first surface212and the second surface214face in directions opposite to each other. The glass component210is has a property to transmit laser light. For example, 940 nm semiconductor laser is the light source of laser light.

When the glass component210is viewed from the user side, the glass component210has a rectangular shape, and a frame-shaped printing216is provided at the outer edge of the first surface212. The printing216is formed by a substance that absorbs laser light, and, for example, an acrylic ink. For example, the thickness of the printing216is less than 30 μm. The thickness of the printing216may be 5 μm or greater. The printing16has, for example, a black color.

A liquid crystal component220is provided in the central part of the first surface212of the glass component210that is not provided with the printing216. The backlight222is provided on the intra-device side of the liquid crystal component220. The resin component230has an opening in the central part of the surface on the user side, and the opening extends through the intra-device sided to form a through hole. The glass component210can be mounted on the opening of the resin component230from the user side. Further, the liquid crystal component220and the backlight222are provided in the through hole. The resin component230includes, for example, an acrylic resin, and the acrylic resin is a material of the same type as the acrylic ink. The first surface212of the glass component210and the resin component230are caused to face each other so as to layer the glass component210and the resin component230.

(2) Laser irradiation step

FIG.3A-3Dare partial cross-sectional views showing steps of manufacturing the display200.FIGS.3A-3Dshow a part ofFIG.2on an enlarged scale. A glass coating218is provided on the second surface214of the glass component210. The glass coating218also has a property to transmit laser light. As shown inFIG.3A, an infrared (IR) laser300is radiated from the second surface214of the glass component210toward the printing216. The IR laser300is transmitted through the glass coating218and the glass component210.

FIG.3Bshows a state that follows the state ofFIG.3A. The IR laser300is transmitted through the glass component210and reaches the printing216. As a result, the printing216is irradiated by the IR laser300.FIG.3Cshows a state that follows the state ofFIG.3B. The printing216generates heat and is dissolved by the irradiation by the IR laser300. The heat of dissolution generated by the printing216dissolves the part of the resin component230near the printing216.FIG.3Dshows a state that follows the state ofFIG.3C. By cooling the part of the resin component230near the printing216after it is dissolved, that part forms the welding part250by being solidified. The welding part250welds the glass component210and the resin component230.

FIG.4is a cross-sectional view showing the structure of the display200.FIG.4shows the entirety of the structure shown inFIG.3D.FIG.4shows a structure as similarly shown inFIG.2but shows that the welding part250is provided between the glass component210and the resin component230, and the welding part250welds the glass component210and the resin component230.

We have conducted an experiment to determine the type of ink used in the printing216and the thickness of the printing216.FIGS.5A-5Bshow the structure of a sample400used in the embodiment.FIG.5Ais a side view of the sample400, andFIG.5Bis a top view of the sample400. A printing416is provided on a first surface416of a glass component410. The combination of the glass component410and the printing316is configured to have a length of 100 mm, a width of 25 mm, and a thickness of 3.0 mm. The resin component430is configured to have, for example, a length of 100 mm, a width of 25 mm, and a thickness of 1.8 mm. The combination of the glass component410and the printing416with the resin component430arranged such that the parts of 12.5 m in the lengthwise direction are layered. The parts that are layered are shown as layered parts460. By welding the glass component410and the resin component430by the IR laser300(not shown) in this state, the welding part450is formed. The part of the resin component430opposite to the layered parts460is a first grip part470a, and the part of the combination of the glass component410and the printing416opposite to the layered parts460is a second grip part470b.

The glass component410is manufactured from a soda-lime blue sheet glass, and the resin component430is manufactured from a PCABS test piece. The PCABS test piece is an acrylic resin. In the experiment, a urethane based ink and an acrylic ink are used to form the printing416. The urethane based ink is 1st:HF GV3 RX01 710Black/2nd:HF SG460 NSY1312T-2Black (from Seiko Advance), and the acrylic ink is IRX-HF Sumi (from Teikoku Printing Inks). Further, the urethane based ink is a material different in nature from the material of the resin component430, and the acrylic ink is a material similar in nature to the material of the resin component430. In the experiment, the thickness of the printing416is varied between 5 μm, 10 μm, and 30 μm. The output of the IR laser used in welding is configured to be15W, the spot diameter to be φ3 (mm), the laser irradiation speed to be 10 (mm/sec), 15 (mm/sec), and 20 (mm/sec).

FIG.6shows the results of experiment on the sample400. The table shows the strength (MPa) and appearance that result from the experiment using the sample400.FIG.6also shows the comparative results obtained when the glass component410and the resin component430are adhered by using a double-sided tape (from 3M). The strength was measured by pulling the first grip part470aand the second grip part470bby a universal tester Autograph AG-X20kNX (from Shimadzu). The appearance was visually inspected. The use of the urethane based ink resulted in the strength of a level that fractures the assembly during transportation and the appearance showing the ink peeling away.

The use of the acrylic ink resulted in the strength of a level that fractures the assembly during transportation when the thickness is configured to be 5 μm and the laser irradiation speed to be 20 (mm/sec) and when the thickness is configured to be 30 μm and the laser irradiation speed to be 20 (mm/sec). In the other conditions, however, the strength is increased as compared with the case of adhesion by a double-sided tape. Further, the thickness of 30 μm and the laser irradiation speed of 10 (mm/sec) resulted in the appearance showing the ink peeling away. In the other conditions, however, no abnormalities were found in the appearance. By increasing the thickness of the acrylic ink from 5 μm, the amount of acrylic ink increases so that the strength (MPa) increases. When the thickness of the acrylic ink reaches 30 μm, on the other hand, the printing416is not dissolved by the IR laser300sufficiently so that the strength (MPa) decreases.

Based on the above, the acrylic ink is more suitable for the printing416than the urethane based ink. In particular, the acrylic ink thickness of the acrylic ink of less 30 μm and 5 μm or greater is suitable. It should be noted that the printing thickness of less than 5 μm is not favorable because it is difficult to ensure a uniform post-coating thickness.

According to the embodiment, the glass component printed with an acrylic ink and the resin component are adhered by laser irradiation so that the strength of adhesion of the glass component and the resin component is increased. Further, the strength of adhesion is increased so that the adhesion area can be decreased. Further, the adhesion area is decreased so that a thin bezel display can be realized and the flexibility of design is increased. Further, the resin component and the printing are made of similar materials so that the strength of adhesion of the glass component and the resin component is increased. Further, the thickness of the printing is configured to be less than 30 μm so that the printing can be dissolved sufficiently. Further, the thickness of the printing is configured to be 5 μm or greater so that the shortage of the acrylic ink is avoided.

One embodiment of the present disclosure is summarized below. An adhesion method of an embodiment of the present disclosure is an adhesion method adapted to adhere a glass component, which has a first surface and a second surface that faces in a direction opposite to the first surface, and a resin component, the method including: causing the first surface of the glass component and the resin component to face each other and layering the glass component and the resin component, the first surface of the glass component being provided with an acrylic ink printing; and radiating laser light from the second surface of the glass component toward the printing and welding the glass component and the resin component by a heat of dissolution of the printing.

According to the embodiment, the glass component printed with an acrylic ink and the resin component are adhered by laser irradiation so that the strength of adhesion of the glass component and the resin component is increased.

The resin component may include an acrylic resin.

In this case, the resin component and the printing are made of similar materials so that the strength of adhesion of the glass component and the resin component is increased.

A thickness of the printing provided on the first surface of the glass component in the layering step may be less than 30 μm. In this case, the printing can be dissolved sufficiently since the thickness of the printing is configured to be less than 30 μm.

A thickness of the printing provided on the first surface of the glass component in the layering step may be 5 μm or greater. Further, the thickness of the printing is configured to be 5 μm or greater so that the shortage of the acrylic ink is avoided.

Described above is an explanation of the present disclosure based on the embodiment. The embodiment is intended to be illustrative only and it will be understood by those skilled in the art that various modifications to constituting elements and processes could be developed and that such modifications are also within the scope of the present disclosure.

According to the adhesion method of the embodiment, a cover glass (glass component) and a case (resin component) are adhered. Alternatively, however, the adhesion method of the embodiment may be used to adhere a glass component other than a cover glass and a resin component other than a case. According to this variation, the scope of application of the embodiment is extended.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2022-6911, filed on Jan. 20, 2022, the entire contents of which are incorporated herein by reference.