JP5564522B2 - Manufacturing method of cover glass for electronic device and manufacturing method of touch sensor module - Google Patents

Description

  The present invention includes a cover glass for a mobile device used for protecting a display screen of a mobile device such as a mobile phone or a PDA (Personal Digital Assistant), and a cover glass for a touch sensor that is a cover member for the sensor substrate of the touch sensor. The present invention relates to a method for manufacturing a cover glass for electronic devices and a method for manufacturing a touch sensor module.

  Conventionally, in order to protect the display screen of a portable device (electronic device) such as a mobile phone or a PDA, an acrylic resin plate having excellent transparency and light weight has been generally used. In recent years, touch-panel portable devices have become the mainstream, and there is a need to improve the strength of the display screen in order to support this touch panel function. Instead of conventional acrylic resin materials, glass materials with high strength even though they are thin Are increasingly being used. Furthermore, compared with conventional acrylic resin materials, mechanical strength (scratch resistance, impact resistance), surface smoothness, protective properties (weather resistance, antifouling properties), appearance, luxury, price, etc. for glass materials , It is superior in any respect.

A cover glass made of such a glass material is generally manufactured by the following process.
The glass material formed into a sheet is cut into a predetermined size by machining (cutting) or etching, and a glass substrate for cover glass is produced.
Next, necessary drilling or outer peripheral shape processing is performed on the glass substrate by machining or etching.

Next, a chemical strengthening process is performed on the glass substrate that has undergone the shape processing. This chemical strengthening treatment is a treatment method in which sodium Na ⁺ in glass is exchanged with potassium K ⁺ having a large ionic radius to form a compressive stress layer on the glass surface. The cover glass is required to have high strength because of impact and pressure.
Next, desired printing is performed on the surface of the glass substrate subjected to the above chemical strengthening treatment.
The cover glass thus completed is incorporated into a portable device.

JP 2003-140558 A

  As described above, the glass substrate for cover glass is subjected to chemical strengthening treatment in order to improve its strength. In the cover glass manufacturing process described above, the chemical strengthening process is performed on the glass substrate for cover glass, and then the printing process is performed. The cover glass printing method is generally screen printing. Usually, the glass substrates are loaded one by one on a screen printing machine, and the printing layers are successively applied. For example, after printing the printing layer A for the first time, the glass substrate is removed from the printing machine. If it is a thermosetting ink, it is heated at a temperature of about 60 to 100 ° C. To pre-dry printing layer A. Next, the glass substrate on which the printing layer A is printed is loaded into a printing machine equipped with the screen of the printing layer B, printing of the printing layer B is performed, and after the glass substrate is removed from the printing machine again, the printing layer B Repeat the process of pre-drying.

  By the way, the glass substrate for cover glass subjected to the chemical strengthening treatment is usually printed at a printing factory or the like in another place. Therefore, it is very rare that the printing process is carried out immediately (continuously) after the glass substrate for cover glass is chemically strengthened. Usually, after the chemical strengthening and before the printing process is performed. In such cases, the glass substrate is transferred and stored. Therefore, during this time, the glass substrate surface may be deteriorated by so-called burning, or foreign substances or chemical components in the atmosphere may adhere to the glass substrate surface and become contaminated. When a printing process is performed on a glass substrate having a surface that has changed in quality or has adhered contamination, the printing ink is smeared or bounced, resulting in a problem that desired printing quality cannot be obtained.

  In Patent Document 1, instead of directly forming an ink image on a tempered glass plate by a method such as screen printing, a film on which a character or a pattern is printed is attached to one side of the tempered glass plate, A protective plate for a portable display device is disclosed in which a pattern is baked and a film-like anti-scattering film is applied to the other surface. This anti-scattering film is for preventing the fragments from being scattered when the tempered glass plate is broken.

Thus, in the said patent document 1, it does not presuppose that it prints directly on the surface of a glass substrate, and the surface of a glass substrate changes in quality before a printing process is implemented after a chemical strengthening process. It has not been recognized or described that there is a problem that this adversely affects the printing process to be performed later.
Although it is conceivable to clean the glass substrate again just before the printing process is performed, the surface of the glass substrate that has once deteriorated can be restored to its original state even if contamination adhered to the surface of the glass substrate can be removed. It is difficult to make it.

  The present invention has been made to solve such a conventional problem, and its purpose is to provide a cover glass for an electronic device that can obtain good print quality when printing is performed on the surface of the glass substrate for cover glass. And a manufacturing method of a touch sensor module that can provide good film forming quality when a transparent conductive film is formed on the surface of a glass substrate for cover glass.

As a result of intensive studies to solve the above problems, the present inventor has found that the above problems can be solved by an invention having the following configuration.
That is, the present invention has the following configuration.
(Configuration 1)
A method of manufacturing a cover glass used in an electronic device, the manufacturing method including a printing step of printing on a surface of a glass substrate for cover glass, wherein the glass substrate for cover glass is made of glass containing at least an alkali metal. And having a step of forming a protective film on the printable surface of the glass substrate for cover glass until the glass substrate for cover glass is subjected to the printing step, to suppress alteration of the surface of the glass substrate. The manufacturing method of the cover glass for electronic devices characterized by these.

(Configuration 2)
The configuration 1 is characterized in that, immediately before the printing step, the protective film is removed or modified, and the surface of the glass substrate from which the protective film has been removed or the modified surface of the protective film is printed. It is a manufacturing method of the cover glass for electronic devices.

(Configuration 3)
A method for manufacturing a cover glass for an electronic device comprising a glass substrate for cover glass, the manufacturing method comprising a printing step of printing on the glass substrate, wherein the glass is formed on a printable surface of the glass substrate. Until the substrate is subjected to the printing process, the protective film is removed or modified immediately before the printing process on the glass substrate on which the protective film for suppressing the deterioration of the glass substrate surface is formed. A method of manufacturing a cover glass for an electronic device, comprising: a step; and the printing step of printing on the surface of the glass substrate from which the protective film has been removed or the surface of the modified protective film.

(Configuration 4)
The cover for an electronic device according to any one of the structures 1 to 3, wherein a surface of the glass substrate for cover glass is washed to form a printable substrate surface, and then a protective film is formed on the glass substrate. It is a manufacturing method of glass.
(Configuration 5)
5. The method for manufacturing a cover glass for an electronic device according to any one of configurations 1 to 4, wherein the glass substrate for cover glass is made of chemically strengthened aluminosilicate glass.

(Configuration 6)
The said protective film consists of a fluorine-type resin material or a silicon-type resin material, It is a manufacturing method of the cover glass for electronic devices in any one of the structures 1 thru | or 5 characterized by the above-mentioned.
(Configuration 7)
The method for producing a cover glass for an electronic device according to any one of Structures 2 to 6, wherein the protective film is removed by oxygen plasma treatment.

(Configuration 8)
The thickness of the glass substrate for cover glasses is 0.3 mm-1.5 mm, It is a manufacturing method of the cover glass for electronic devices in any one of the structures 1 thru | or 7 characterized by the above-mentioned.

(Configuration 9)
A method for manufacturing a touch sensor module comprising a glass substrate for a cover glass and detecting a user operation, the manufacturing method including a film forming step of forming a transparent conductive film on the glass substrate, With respect to the glass substrate on which the protective film for suppressing the alteration of the surface of the glass substrate is formed on the surface of the glass substrate on which film formation is possible, the glass substrate is subjected to the film formation step. And a step of removing or modifying the protective film, which is performed immediately before the film process, and a film forming step of forming a film on the surface of the glass substrate from which the protective film has been removed or the surface of the modified protective film. This is a method for manufacturing a touch sensor module.

(Configuration 10)
The printing step is performed before the film formation step, and further includes a printing step of printing on the surface of the glass substrate for cover glass, and the step of removing or modifying the protective film replaces the film formation step. The printing step is performed on the glass substrate surface from which the protective film is removed or the modified protective film surface is printed, and the film forming step is performed after the printing step. 10. The touch sensor module manufacturing method according to Configuration 9, wherein a transparent conductive film is formed on the removed glass substrate surface or the modified protective film surface.

According to the present invention, the surface of the glass substrate for cover glass can be suppressed by providing a protective film that protects the surface on the printing surface side of the glass substrate for cover glass until just before printing. When printing is performed on the, good print quality can be obtained.
Further, according to the present invention, in the manufacture of the touch sensor module, the surface of the glass substrate is altered by providing a protective film for protecting the surface of the glass substrate for the cover glass until just before the film formation of the transparent conductive film. Therefore, when a transparent conductive film is formed on the surface of the glass substrate for cover glass, good film forming quality can be obtained.

It is a schematic sectional drawing for demonstrating one Embodiment of the manufacturing method of the cover glass for portable devices which concerns on this invention. It is a top view which shows an example of the shape of the glass substrate for cover glasses.

Hereinafter, embodiments of the present invention will be described in detail.
The cover glass for portable devices as the cover glass for electronic devices made of the glass material according to the present invention is manufactured by a process as described below.
First, a glass material formed into a sheet is cut into a predetermined size by machining or the like to produce a glass substrate for cover glass.

A sheet glass material (sheet glass) having a thickness of, for example, about 0.5 mm manufactured by the downdraw method or the float method is laminated (laminated) (for example, about several tens of sheets) and predetermined using a glass cutter. Cut into small pieces. Of course, the sheet-like glass material may be processed one by one, but if the laminated ones are cut at once, the laminated pieces can be shaped at the same time in the next shape processing step, which is advantageous in production. It is.
The size of the small piece may be determined in consideration of the size of the product cover glass (product size) plus a margin necessary for processing the outer peripheral shape.

  In addition, the thickness of the glass substrate for the cover glass is preferably in the range of, for example, about 0.3 mm to 1.5 mm, more preferably from the viewpoint of meeting the market needs for recent thinning and weight reduction of portable devices. The range is about 0.5 mm to 0.7 mm.

The present invention can be suitably applied when a glass substrate for cover glass made of glass containing an alkali metal is used. Glass containing an alkali metal reacts with moisture and carbon dioxide in the atmosphere, and its surface is easily altered. A typical example is glass burning.
As described above, when the surface of the glass substrate is altered, it is difficult to obtain good print quality when printing is performed on the surface. ADVANTAGE OF THE INVENTION According to this invention, the quality change of the glass substrate surface which should be printed can be suppressed.

  The present invention can be suitably applied particularly to a glass substrate for cover glass made of glass containing sodium or glass containing sodium and lithium. Among alkali metals, sodium and lithium are particularly likely to cause the glass surface to burn, but according to the present invention, the glass substrate surface is burnt until the glass substrate for the cover glass is subjected to the printing process. If the printing process is suppressed, good print quality can be obtained.

Examples of the glass containing an alkali metal include soda lime glass and alkali-containing aluminosilicate glass. In the present invention, from the viewpoint of various properties required for the glass substrate for cover glass, the glass constituting the glass substrate for cover glass is particularly preferably an aluminosilicate glass containing an alkali metal. A glass substrate made of an aluminosilicate glass containing such an alkali metal has a high strength after chemical strengthening and is good. Such aluminosilicate glass, for example, SiO ₂ is 58 to 75 wt%, Al ₂ O ₃ 0 to 20 wt%, Li ₂ O is 0 to 10 wt%, Na ₂ O 4 to 20 wt% An aluminosilicate glass containing as a main component can be used.

  Note that an etching method can also be applied as means other than the above-described machining. That is, a photosensitive resist (photosensitive polymer material) is applied to the surface of the sheet-like glass material, subjected to predetermined exposure and development, and a resist pattern having a cutting line pattern (the resist exists on the cutting line). Pattern). Then, the glass material on which such a resist pattern is formed is cut into small pieces of a predetermined size by wet etching using an etching solution that can dissolve the glass material (for example, an acidic solution containing hydrofluoric acid as a main component). The remaining resist pattern is peeled off and washed.

  Next, necessary drilling or outer peripheral shape processing is performed on the glass substrate for cover glass processed into small pieces of a predetermined size by machining or etching.

  FIG. 2 is a plan view showing an example of the shape of the glass substrate for cover glass. In the example shown in FIG. 2, the glass substrate 1 for cover glass has an outer shape 1a, a notch 1b, an ear hole 1c, and a key operation hole 1d. Such drilling and outer peripheral shape processing may be machined by sandblasting or the like, or these drilling processing and outer peripheral shape processing may be collectively performed by etching. In particular, etching is advantageous for complex shape processing. Note that the etching method is the same as the etching method in the above-described cutting process. Moreover, you may use together machining and an etching process according to a process shape.

  Next, a chemical strengthening process is performed with respect to the glass substrate which finished shape processing. If the glass substrate has been processed in a laminated state so far, it is peeled (separated) one by one before chemical strengthening.

  As a method of chemical strengthening treatment, for example, a low temperature ion exchange method in which ion exchange is performed in a temperature range that does not exceed the temperature of the glass transition point, for example, a temperature of 300 ° C. to 500 ° C. is preferable. The chemical strengthening treatment is a process in which a molten chemical strengthening salt is brought into contact with a glass substrate, whereby an alkali metal element having a relatively large atomic radius in the chemical strengthening salt and a relatively small atomic radius in the glass substrate. This is a treatment in which an alkali metal element is ion-exchanged, an alkali metal element having a large ion radius is permeated into the surface layer of the glass substrate, and compressive stress is generated on the surface of the glass substrate. As the chemical strengthening salt, alkali metal nitric acid such as potassium nitrate or sodium nitrate can be preferably used. A chemically strengthened glass substrate is improved in strength and excellent in impact resistance, and thus is suitable for a cover glass used for a portable device that requires impact and pressure and requires high strength.

Next, it moves to the printing process which performs desired printing on the surface of the glass substrate which performed the above chemical strengthening process.
As described above, the glass substrate for cover glass subjected to the chemical strengthening treatment is usually printed at a printing factory or the like. Therefore, it is very rare that the printing process is performed immediately (continuously) after the chemical strengthening treatment of the glass substrate for cover glass. Usually, the printing process is performed after the chemical strengthening treatment. In the meantime, glass substrates are transferred to printing factories and stored in printing factories. In order to ensure good print quality in the printing process, the glass substrate surface may be altered by so-called burning during the transfer and storage of the glass substrate, or foreign substances in the atmosphere on the glass substrate surface. It is necessary to prevent chemical components and the like from becoming contaminated.

  Therefore, in the manufacturing method of the cover glass for portable devices as the cover glass for electronic devices according to the present invention, the cover glass substrate until the cover glass substrate is subjected to the printing step on the printable surface of the cover glass substrate. In addition, a protective film for suppressing deterioration of the glass substrate surface is formed.

Hereinafter, a description will be given with reference to FIG.
FIG. 1 is a schematic cross-sectional view for explaining an embodiment of a method for producing a cover glass for portable equipment as a cover glass for electronic equipment according to the present invention.
First, the glass substrate 1 for cover glass is washed, for example, to form a printable glass substrate surface (see FIG. 1A). Here, “printable” means that printing with good print quality can be performed. For example, the printing ink does not bleed or bounce during printing, and the adhesion of the printed layer to the glass substrate after printing and the solvent resistance of the printed layer are good.

  The glass substrate 1 for cover glass in this case is a glass substrate subjected to the above-described chemical strengthening treatment. In the present embodiment, since the printing process is performed after the chemical strengthening process of the glass substrate as described above, it is preferable to perform, for example, substrate cleaning on the glass substrate subjected to the above chemical strengthening process. is there.

  Examples of the cleaning method in this case include acid cleaning, alkali cleaning, combined use of acid cleaning and alkali cleaning, and the like, especially if it is a cleaning method capable of forming a clean glass substrate surface that is printable, that is, suitable for printing. There are no restrictions. For example, a method of performing vapor drying of isopropyl alcohol (IPA) after sequentially immersing the glass substrate that has been subjected to the chemical strengthening treatment in respective washing tanks such as sulfuric acid, a neutral detergent, and pure water. In the case of the method of immersing the glass substrate in such a cleaning tank, the entire glass substrate is cleaned, but not limited to this, for example, the surface of the glass substrate that becomes the printing surface (on the printing surface side) is selectively cleaned. It doesn't matter.

  Further, it is particularly preferable that the cleaning process is performed by applying ultrasonic waves. By cleaning the glass substrate by applying an ultrasonic wave, the efficiency of removing foreign substances, contaminants and the like on the surface of the glass substrate is increased, and the cleanliness of the surface of the glass substrate after cleaning can be further improved.

  Next, as shown in FIG.1 (b), a protective film is formed in said printable surface of the glass substrate 1 for cover glasses. In this case, the protective film 2 may be formed not only on the entire surface of the printable surface but only within a range that covers a region where printing is actually performed.

The said protective film 2 is for suppressing the quality change of the glass substrate surface until the glass substrate 1 for cover glasses is provided to a printing process.
There are points to be considered when selecting the material of the protective film 2.

First, from the viewpoint of protecting the printing surface (surface on which printing is performed) by suppressing the alteration of the glass substrate surface until immediately before the printing step, the protective film 2 is composed of moisture and carbon dioxide in the atmosphere that cause alteration. It is necessary to provide characteristics that are difficult to transmit.
Second, it is preferable that the protective film 2 can be formed on the surface of the glass substrate by a simple method without using a vacuum apparatus or the like.
Thirdly, in the present embodiment, since the protective film 2 is removed immediately before the printing process, no residue remains on the surface of the glass substrate after the protective film 2 is removed. It is necessary that the protective film 2 can be removed so that the surface of the glass substrate suitable for printing is exposed again.

  Therefore, in consideration of the above viewpoint, it is preferable to use a material containing a general organic polymer compound as the material of the protective film 2. Further, particularly when the weight is placed on the third aspect, among the materials containing the organic polymer compound, for example, a fluorine-based resin material (for example, a perfluoropolyether compound) or a silicon-based resin material (for example, a silicone resin) The material which reduces surface energy, such as), is mentioned preferably.

  Moreover, when using the material containing said organic polymer compound as a material of the said protective film 2, the said protective film 2 can be apply | coated and formed by simple methods, such as a normal coater coating method, for example.

  The coating thickness of the protective film 2 is not particularly limited in the present invention, but is preferably in the range of 0.5 nm to 3000 nm, for example. If the film thickness is less than 0.5 nm, there is a possibility that the function of suppressing the alteration of the glass substrate surface and protecting the printing surface cannot be obtained until immediately before the printing step. On the other hand, if the film thickness exceeds 3000 nm, it may be difficult to completely remove the protective film so that no residue remains on the surface of the glass substrate immediately before the printing process.

  The protective film 2 has a function of protecting the printing surface by suppressing the alteration of the glass substrate surface until immediately before the printing process, but at the same time, contaminants such as foreign substances and chemical components in the atmosphere adhere to the glass substrate surface. It also has a function that can prevent this.

Next, as shown in FIG. 1C, the protective film 2 is removed immediately before the printing process. As described above, the glass substrate 1 is usually used for a printing factory or the like after the protective film 2 is formed on the surface of the glass substrate until the glass substrate 1 is actually subjected to the printing process. Transport, storage there, etc., and there are movements of places and passage of time.
The method for removing the protective film 2 differs somewhat depending on the material of the protective film. For example, when a fluorine-based resin material is used for the protective film, the protective film 2 is removed by, for example, oxygen plasma treatment with a fluorine-based gas added. Can do.

  Next, as shown in FIG. 1D, a printing process is performed. That is, a desired printing layer (ink layer) 3 is formed on the surface of the glass substrate from which the protective film 2 has been removed by a screen printing method or the like. As described above, the printing surface (the surface on which printing is performed) of the glass substrate is protected by the protective film 2 for suppressing the alteration of the surface of the glass substrate until immediately before the printing process, so that printing is possible (that is, printing). The glass substrate surface suitable for the printing is exposed by removing the protective film 2. Therefore, by performing the printing process on the glass substrate 1 at this time, it is possible to perform printing with good print quality. For example, the printing layer can be formed without causing the printing ink to bleed or bounce during printing, and the adhesion of the printed layer to the glass substrate after printing, the solvent resistance of the printing layer, and the like are improved.

Further, on the main surface side of the glass substrate 1 incorporated toward the inside of the portable device (that is, the glass substrate surface side from which the protective film is removed), in addition to the printed layer, for example, at least one of an insulating layer and a transparent conductive layer It is also possible to form a touch sensor module for detecting the operation of the user of the portable device. The present invention also provides a method for manufacturing a touch sensor module.
That is, this invention is a manufacturing method of the touch sensor module for providing a glass substrate for cover glasses, and detecting a user's operation, Comprising: This manufacturing method forms a transparent conductive film with respect to the said glass substrate. The glass substrate including a film forming step, wherein a protective film for suppressing deterioration of the glass substrate surface is formed on the surface of the glass substrate where film formation is possible until the glass substrate is subjected to the film forming step In contrast, the step of removing or modifying the protective film, which is performed immediately before the film forming step, and forming the film on the surface of the glass substrate from which the protective film has been removed, or on the surface of the modified protective film A method for manufacturing a touch sensor module, comprising a film forming step.

  The touch sensor module manufacturing method may further include a printing step that is performed before the film forming step and performs printing on a surface of the glass substrate for cover glass, and the step of removing or modifying the protective film includes The film forming step is performed immediately before the printing step, and the printing step performs printing on the surface of the glass substrate from which the protective film has been removed or the surface of the modified protective film. A method of manufacturing a touch sensor module, comprising: forming a transparent conductive film on the glass substrate surface from which the protective film has been removed or the modified protective film surface after the printing step.

  In the present invention, the printed surface (surface on which printing is performed) of the glass substrate is protected by the protective film 2 for suppressing the alteration of the glass substrate surface, so that the insulating film is removed or modified after the protective film 2 is removed or modified. Even when a layer or a transparent conductive layer is formed, the film-forming quality (adhesion) of these layers to the glass substrate is good.

  The transparent conductive layer is formed with a predetermined thickness. The “predetermined thickness” of the transparent conductive layer is, for example, 100 nm or less when formed by a sputtering method, and includes a transparent resin serving as a binder when formed by a printing method. 1000 nm or less.

Specifically, a transparent conductive layer, for example, an ITO (Indium Tin Oxide) film is formed using a sputtering method or the like, and laser patterning using a photolithography technique, a YAG (Yttrium Aluminum Garnet) fundamental wave, a CO ₂ laser, or the like. It is formed by processing the transparent conductive layer into a desired pattern shape using a technique. In addition, the connection part (metal wiring) is formed by forming a metal conductive material on the surface of the printing region of the glass substrate by using a sputtering method or the like, and using a photolithography technique or the like to form the metal film. Is formed into a desired pattern shape.

In addition, an insulating layer is formed between the glass substrate surface and the transparent conductive layer and between the glass substrate surface and the connection portion (metal wiring), as necessary. This insulating layer is preferably formed using an insulating material having transparency, for example, an inorganic material such as SiO ₂ . The insulating layer is preferably formed to a thickness of about 50 to 1000 mm using, for example, a sputtering method.

The cover glass thus completed is incorporated into a portable device.
In the case of the present embodiment, it is desirable that the contact angle between the glass substrate from which the protective film 2 has been removed and the printing ink is small. The print quality in the printing process is deteriorated due to the above-mentioned alteration of the glass substrate surface, but is also related to the contact angle of the glass substrate with respect to the printing ink. When the contact angle of the glass substrate with respect to the printing ink is smaller, the repelling of the printing ink is reduced, and a more preferable printing quality can be obtained. For example, it is particularly preferable to use a printing ink prepared so that the contact angle is 15 degrees or less.

  As described above, according to the method for manufacturing a cover glass for a portable device as a cover glass for an electronic device according to the present embodiment, for example, after the glass substrate for cover glass is chemically strengthened, until the printing process is performed. Even when there is a lapse of time or movement of place between the two, the glass substrate surface can be prevented from being altered by providing a protective film that protects the printing surface side of the glass substrate until immediately before the printing step. Therefore, when printing is performed on the surface of the glass substrate in the printing process, good print quality can be obtained. As a result, a high-quality portable device cover glass is obtained.

  In the present embodiment, the manufacturing process in which the printing process is performed after the shape processing of the glass substrate for cover glass and the chemical strengthening process is described as an example. However, the manufacturing process is not limited to this, for example, the chemical strengthening process. The present invention can also be applied to a manufacturing process in which shape processing is performed later and then a printing process is performed.

  As described above, the protective film 2 is for suppressing the alteration of the glass substrate surface until immediately before the printing process, and is basically removed from the glass substrate immediately before the printing process. If it is possible to print directly on the surface of the protective film 2 without removing the protective film 2, it is possible to omit the step of removing the protective film 2 immediately before the printing process.

  On the other hand, the protective film 2 for suppressing deterioration of the surface of the glass substrate until immediately before the printing step is not removed from the glass substrate immediately before the printing step, and the protective film surface is subjected to the above-described modification treatment to thereby remove the protective film. It is also possible to print directly on the surface of the protective film 2 without removing 2.

Here, a screen printing method is generally used as a cover glass printing method. In order to enable screen printing on the surface of the protective film 2, for example, it is preferable to perform a modification process that reduces the contact angle with water on the surface of the protective film 2.
Examples of such a protective film modification treatment include a method of exposing the surface of the protective film 2 to ultraviolet irradiation or oxygen plasma exposure. Regarding conditions such as irradiation energy and irradiation amount (irradiation time) in the case of performing ultraviolet irradiation, and conditions such as plasma energy and exposure time in the case of oxygen plasma exposure, preferable conditions can be selected as appropriate. Note that the thickness in the depth direction of the modified layer formed on the surface layer of the protective film 2 can be adjusted by these ultraviolet irradiation conditions or oxygen plasma exposure conditions.

Hereinafter, the present invention will be described in more detail with reference to specific examples. Here, the cover glass for portable devices as the cover glass for electronic devices will be described. In addition, this invention is not limited to the Example of the following cover glass for portable devices.
Example 1
The following (1) glass substrate processing step, (2) shape processing step, (3) chemical strengthening step, (4) substrate cleaning (cleaning) step, (5) protective film forming step, (6) protective film removing step (7) The cover glass of the present Example was manufactured through the printing process.

(1) Glass substrate processing step First, a glass substrate for cover glass was produced by cutting out a predetermined size from a 0.5 mm thick plate glass made of an aluminosilicate gate glass produced by a downdraw method or a float method. As the aluminosilicate _glass, SiO 2: 58 to 75 _{wt%, Al} 2 O 3: _{5~23 wt%,} Li 2 O: _{3~10 wt%,} Na 2 O: _4~13 chemical containing wt% Tempered glass was used.

(2) Shape processing step Next, a hole was made in the glass substrate using a wet etching method, and the shape of the outer periphery as shown in FIG.

(3) Chemical strengthening process Next, the glass substrate which finished the said shape process was chemically strengthened. For chemical strengthening, a chemical strengthening solution in which potassium nitrate and sodium nitrate are mixed is prepared, this chemical strengthening solution is heated to 380 ° C., and the cleaned and dried glass substrate after the above shape processing is immersed for about 4 hours. Was done.

(4) Substrate cleaning (cleaning) process The glass substrate that has been subjected to the chemical strengthening treatment is immersed in a cleaning bath of sulfuric acid, neutral detergent, pure water, and IPA (steam drying), and ultrasonic waves are applied to some baths. Washed and dried. Thus, the surface of the glass substrate was made a printable (suitable for printing) surface.

(5) Protective film formation process The coating liquid (liquid temperature 25 degreeC) which adjusted fluororesin (EGC-1720 by 3M company) to the suitable density | concentration with the solvent was adjusted. Using a single-side coating apparatus, a protective film made of the fluororesin is applied to any one of the opposing main surfaces (becomes a printing surface) of the glass substrate that has been subjected to the substrate cleaning step, and is 100 ° C. And dried with hot air. The coating thickness of the protective film was 10 nm.

Here, the glass substrate that had been subjected to the protective film formation step was packed and transported to a printing factory in another location by truck. Furthermore, it was stored in the printing factory for about one month in a packaged state.
(6) Protective film removal process Immediately before carrying out the printing process, the above-mentioned packaging is removed, the glass substrate inside is taken out, and the protective film formed on the surface of the glass substrate is subjected to oxygen plasma treatment to which a fluorine-based gas is added. Removed by.

(7) Printing process The printing process was implemented with respect to the glass substrate from which the said protective film was removed.
That is, a predetermined printing layer (ink layer) was formed by screen printing on the glass substrate surface (printing surface) on the surface side from which the protective film was removed. In this example, a total of three printed layers were formed. In addition, the thermosetting ink was used and it dried with hot air at the temperature of about 60-100 degreeC after printing of each printing layer.

Thus, the cover glass of this example was manufactured.
In this embodiment, as described above, the printing surface on the surface of the glass substrate is protected by the protective film for suppressing the alteration of the surface of the glass substrate until immediately before the printing process. (Suitable) The state of the glass substrate surface is maintained. Therefore, by removing the protective film immediately before the printing step, desired printing could be performed on the glass substrate surface. Further, the print quality (according to the visual evaluation of the skilled worker) was a level at which there was no problem as a product.

Further, the cover glass of the present example was exposed to an environmental test (heat cycle: repeated from 80 ° C. to −40 ° C., 10 cycles) and stored in a high temperature and high humidity environment (65 ° C., 90% RH, 96 hours). Later, as a result of a cross-cut test (formation of a 1 mm pitch grid with a cutter), it was confirmed that there was no peeling of the printed layer. Note that the cross-cut test was performed in accordance with JIS K5400.
That is, it was confirmed that the cover glass obtained in this example had good printing quality and good adhesion of the printed layer to the glass substrate.

(Example 2)
In the protective film formation step of Example 1 (5), a coating liquid (liquid temperature 25 ° C.) prepared by adjusting the concentration of the KY100 series (trade name) manufactured by Shin-Etsu Chemical Co., Ltd. to a suitable concentration with a solvent is used as a fluororesin. Using a coating apparatus, a protective film made of the fluororesin is applied to any one of the opposing main surfaces (becomes a printing surface) of the glass substrate that has been subjected to the substrate cleaning step, at 100 ° C. The film was dried with hot air to form a protective film having a coating thickness of 10 nm. Except for this, a cover glass was produced in the same manner as in Example 1.

  Also in the present embodiment, the printing surface on the surface of the glass substrate is protected by a protective film for suppressing the alteration of the surface of the glass substrate until immediately before the printing step, so that glass that can be printed (that is, suitable for printing) is used. The state of the substrate surface is maintained. Therefore, by removing the protective film immediately before the printing step, desired printing could be performed on the glass substrate surface. Further, the print quality (according to the visual evaluation of the skilled worker) was a level at which there was no problem as a product.

In addition, the cover glass of this example was exposed to an environmental test in the same manner as in Example 1, and the result of cross-cut test after storage in a high temperature and high humidity environment (65 ° C., 90% RH, 96 hours). Then, it was confirmed that there was no peeling of the printed layer.
That is, it was confirmed that the cover glass obtained in this example had good printing quality and good adhesion of the printed layer to the glass substrate.

(Comparative example)
As in Example 1, Example 1 was carried out without performing the above (5) protective film forming step and (6) protective film removing step on the glass substrate that had been subjected to the above (4) substrate cleaning (cleaning) step. The same printing process was carried out. However, the glass substrate that had been subjected to chemical strengthening and subsequent substrate cleaning was packed and transported by truck and stored in a printing factory as in Example 1.
The cover glass of this comparative example thus obtained could be printed once, but the print quality required for the product could not be obtained. In addition, it is assumed that the cause is due to the glass substrate track transportation, the alteration of the surface of the glass substrate that occurs during storage in the printing factory, the adhesion of foreign matters and other contaminants in the atmosphere, and the like.

1 Glass substrate for cover glass 2 Protective film 3 Printed layer (ink layer)

Claims (7)

A method of manufacturing a cover glass used in an electronic device,
The manufacturing method includes a printing step of printing on the surface of the glass substrate for cover glass,
The glass substrate for cover glass is made of glass containing at least an alkali metal,
A printable surface of the cover glass for a glass substrate, have a step of forming a protective film for the cover glass for the glass substrate until subjected to the printing process, to suppress the deterioration of the glass substrate surface,
Immediately before the printing step, the protective film is modified, and the modification is a process for reducing the contact angle with water on the surface of the protective film, and printing is performed on the modified surface of the protective film. The manufacturing method of the cover glass for electronic devices characterized by these. Washed the cover glass for a glass substrate surface, to form a printable substrate surface, method of manufacturing then a cover glass for an electronic device according to claim 1, wherein the forming a protective film on the glass substrate . The method for producing a cover glass for an electronic device according to claim 1 or 2 , wherein the glass substrate for cover glass is made of chemically strengthened aluminosilicate glass. The said protective film consists of a fluorine resin material or a silicon-type resin material, The manufacturing method of the cover glass for electronic devices in any one of the Claims 1 thru | or 3 characterized by the above-mentioned. The thickness of the glass substrate for cover glasses is 0.3 mm-1.5 mm, The manufacturing method of the cover glass for electronic devices in any one of the Claims 1 thru | or 4 characterized by the above-mentioned. A method for manufacturing a touch sensor module comprising a glass substrate for a cover glass and detecting a user operation,
The manufacturing method includes a film forming step of forming a transparent conductive film on the glass substrate,
The glass substrate on which the protective film for suppressing the alteration of the glass substrate surface is formed until the glass substrate is subjected to the film forming step on the surface where the glass substrate can be formed,
Performed immediately before the film formation step, a step of the protective film reformed,
The modification is a treatment for reducing the contact angle with water on the surface of the protective film,
Method of manufacturing a touch sensor module which comprises the said film-forming step of performing film formation on the surface of the protective film was reformed. It is performed before the film forming step, and further includes a printing step of printing on the surface of the glass substrate for cover glass,
The step of modifying the protective film is performed immediately before the printing step in place of the film-forming step,
The printing process, by printing on the surface of the protective film was reformed,
The film-forming step, after the printing step, the manufacturing method of the touch sensor module according to claim 6, characterized in that to form the transparent conductive film reformed said protective layer surface.

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