JPH04219348A - Production of glass with functional thin film and production of combiner for head up display - Google Patents

Abstract

PURPOSE:To efficiently form an excellent thin film on part of a glass substrate of large area. CONSTITUTION:A liquid containing 2.0-8.0wt.% calculated as metal oxide of a metal alkoxide and having 20-120cP viscosity is printed on a glass plate 1 by flexographic printing. Then the glass is heated for bending processing and/or tempering processing and simultaneously the film subjected to flexographic printing is burnt to form a functional thin film 2 consisting essentially of the metal oxide.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a method for manufacturing glass with a functional thin film, and a head-up display (H
The present invention relates to a method for manufacturing a combiner for UD).

0002

2. Description of the Related Art Conventionally, physical methods such as vacuum evaporation and sputtering have been known as methods for forming metal oxide thin films on substrates such as glass. Wet methods are also known, such as dipping, roll coating, meniscus coating, and screen printing, in which a liquid containing a raw material that can become a metal oxide is applied.Wet methods have lower production costs than physical methods. It has the advantage of being able to lower the

0003

[Problems to be Solved by the Invention] However, both physical methods and wet methods require masking during film formation or etching after film formation if a film with good appearance is desired to be formed on only a portion of a large-area substrate. In addition, it is difficult to form a film with an excellent appearance, resulting in a complicated manufacturing process and high production costs. In addition, the viscosity of the coating solution in the wet method was high, and the leveling property (easiness of making the surface even and uniform) was poor. The object of the invention is to overcome the aforementioned drawbacks of the prior art.

0004

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and includes: (a) flexographic printing of a liquid for forming a functional thin film containing a metal oxide raw material onto a predetermined portion of a glass plate; (b) bending the glass plate of (a), and/or
The present invention provides a method for manufacturing glass with a functional thin film, which includes the step of heating the printed film for strengthening and simultaneously firing the printed film to form a functional thin film containing a metal oxide as a main component. be.

FIG. 1 shows the production process of the method for producing glass with a functional thin film according to the present invention. In the present invention, first, FIG.
a) As shown in FIG. 1, the glass plate 1 is cut into a desired shape. Preferably, the cut edges are then chamfered and cleaned.

Next, as shown in FIG. 1(b), a functional thin film forming liquid containing a raw material that can be turned into a metal oxide by firing is flexographically printed on a predetermined portion of the glass plate 1 to form a printed film 2. do.

[0007] In the present invention, flexographic printing refers to letterpress rotary printing using a plate material (flexographic plate) made of an elastic material (rubber, plastic, etc.). FIG. 4 is a sectional view of an example of a flatbed flexo printing machine used in the present invention. In flexo printing, doctor roll (rubber roll) 1
1 and anilox roll (ceramic roll) 12 rotate, the functional thin film forming liquid 13 is uniformly supplied onto the flexo plate 15 wound around the plate cylinder 10, and as the plate cylinder 10 rotates, the table The glass plate 1 on the glass plate 14 is moved, and the liquid for forming a functional thin film is applied from the flexo plate 15 to the glass plate 1.

In flexographic printing, as shown in FIG.
Since printing is always carried out in line contact with the glass plate 1 using a roll of rubber letterpress wrapped around the plate cylinder 10, continuous uniform printing is possible over the printing area.

[0009] In addition, a liquid for forming a functional thin film (approximately 20 to 120 cP, 25 °C
value) can be used suitably, so the time required for leveling (to make the surface of the applied liquid even and uniform) is short, and there is no need to mix organic substances with large molecular weights into the functional thin film forming liquid. Since it is sufficient to use a solvent that mostly evaporates near room temperature, there is little change in weight due to membrane baking, and the membrane does not become porous.

The solvent for the liquid for forming a functional thin film used in the present invention is not particularly limited as long as it can dissolve the raw materials, such as alcohol, glycol, cellosolve, or carbitol, and may be selected as appropriate. . However, if the solvent evaporates too easily, it will evaporate during printing, the solid content concentration in the liquid will increase, the film thickness will increase, and it will be difficult to obtain a uniform film. On the other hand, if a solvent that is difficult to evaporate is used, it will be difficult to bake completely, and the mechanical strength and chemical resistance of the film after baking will be poor. Considering this point, hexylene glycol can be preferably used as the solvent.

[0011] The liquid for forming a functional thin film has a temperature of 20 to 120 c.
The viscosity is preferably adjusted to P (centipoise) (25° C.). If the viscosity is less than 20 cP, the fluidity of the liquid will be too high, resulting in insufficient flexographic printing stability or failure to obtain a desired film thickness after printing, and if the viscosity is greater than 120 cP, This is because the quality of the printed film after firing tends to become porous, resulting in poor chemical and mechanical durability, which is undesirable.

The liquid for forming a functional thin film contains a metal oxide raw material, and such raw material is preferably a metal alkoxide. For example, Ti, Ta, Zr, In,
Alkoxides such as Sn, Si, etc., or mixed alkoxides of one or more of these can be used. The specific material may be selected in consideration of the optical properties required for the intended functional thin film.

For example, when it is desired to obtain a reflective film for a HUD combiner or the like as a functional thin film, the refractive index n of the reflective film should be 1.5 or more, particularly about 1.8 to 2.3. , metal alkoxide may be selected. For example, TiO2 (n=approximately 2.2 to 2.3), ZrO2 (n
= approx. 2.0 to 2.1), Ta2O5 (n = approx. 2.
1), SnO2 (n=approximately 1.9 to 2.0), etc., to obtain a single oxide film, an alkoxide of each metal may be used, or a composite oxide of these, such as T
iO2- SiO2, ZrO2- SiO2, Ti
An appropriate metal alkoxide may be mixed and adjusted so as to obtain a composite oxide film such as O2-ZrO2 or In2O3-SnO2. It is preferable to mix Si alkoxide in that the adhesion to the substrate glass plate 1 is improved.

Further, when it is desired to form a low reflection film as a functional thin film, Si alkoxide or the like may be used so as to obtain a low refractive index film. In addition, when it is desired to obtain a conductive film for use in antennas, humidity sensors, dew condensation sensors, etc. as functional thin films, In2O3-SnO2, SnO2:F
, SnO2:Sb or the like, a functional thin film forming liquid may be prepared by using an appropriate metal alkoxide and adding a dopant.

[0015] Furthermore, when it is desired to obtain a colored film for decoration, display, etc. as a functional thin film, a suitable metal alkoxide is used and a coloring agent, pigment, etc. are added to form a functional thin film, depending on the purpose. Just adjust the liquid.

Preferably, the metal alkoxide is contained in the functional thin film forming liquid in an amount of 2.0 to 8.0% by weight in terms of metal oxide. When the liquid for forming a functional thin film is fired after flexographic printing, most of it becomes gas and disappears, leaving a functional thin film mainly composed of metal oxides. If the metal alkoxide content is less than 2.0% by weight in terms of metal oxide, the thickness of the functional thin film after firing will be too thin, resulting in poor chemical and mechanical stability and poor uniformity. On the other hand, if the content exceeds 8.0% by weight, the film thickness after firing will become too thick, resulting in poor scratch resistance, and if it becomes even thicker, cracks will occur. , undesirable.

Next, as shown in FIG. 1(c), the glass plate 1 having the printed film 2 is subjected to bending and/or reinforcing processing (bending processing, reinforcing processing, or bending and reinforcing processing). ), and at the same time, the printed film 2 is fired to form a functional thin film. The heating temperature may be any temperature necessary for bending or strengthening, and is suitably about 550 to 650°C. It is possible to pre-fire the printed film at about 500 to 600°C before bending and/or strengthening, but as mentioned above, if firing is performed at the same time as bending and/or strengthening, manufacturing This has the advantage of simplifying the process, improving productivity, and reducing manufacturing costs.

When performing the bending process, it is preferable to perform the bending process so that the surface on which the printed film is formed is concave, as shown in FIG. This is because if the surface on which the printed film is formed is bent into a convex shape, cracks will appear in the printed film, making it difficult to obtain a functional thin film with an excellent appearance.

Furthermore, as shown in FIG. 1(b)', the printed film can be dried before being subjected to heating and bending and/or reinforcing processing. This is preferable because it prevents dirt and dust from adhering during heating for bending and/or strengthening (c). A suitable drying temperature is about 50 to 200°C.

The method for producing glass with a functional thin film according to the present invention has been explained above.
The manufacturing method of the D combiner will be explained.

[0021] HUD combiners are often used as windshield glass for vehicles and other transport aircraft, and therefore, in such applications, laminated glass is almost always used from the standpoint of safety. The production of a HUD combiner on which a thin film is formed will be explained as an example.

The steps up to (c) in FIG. 1 are as described above. FIG. 1(c) shows an example in which a glass plate 1 having a printed film 2 is overlapped with another glass plate 3 to be laminated and subjected to bending processing.

Next, as shown in FIG. 1(d), the bent and/or reinforced glass plate 1 is placed together with the other glass plate 3 so that the functional thin film is exposed, and the plastic A combiner for a HUD is manufactured by bonding via the interlayer film 4 and laminating into glass.

The functional thin film used as a HUD combiner has a visible light transmittance (T) that is necessary for safety glass.
V) In order to be able to clearly reflect the projected image while maintaining 70% or more, the functional thin film is formed with an optical thickness (the product of the refractive index n of the film and the actual film thickness d) of 400 to 2300 Å. It is preferable that In order to achieve such an optical film thickness, it is preferable to adjust the film thickness of the flexographic printing film in FIG. 1(b) by taking into account the reduction in film thickness due to baking.

[0025]

[Example 1] The surface of a cut and chamfered ordinary float glass plate 1 having a thickness of 2 mm was polished with cerium oxide, thoroughly rinsed with pure water, and dried by blowing nitrogen gas. This glass surface contains 5.5% by weight of Ti and Si alkoxides in terms of oxides, and 30cP (2
A functional thin film forming liquid having a viscosity of 5°C) was flexographically printed and dried in a clean oven at 120 to 130°C for 10 to 15 minutes. The surface of the printed film at this time was completely dry, and there was no fear of damage to the film even if dirt or dust adhered to it.

[0026] The dried glass is stacked with another glass plate 3 (bronze color, 2 mm thick), with the surface on which the printed film 2 is formed as the exposed surface, as shown in Fig. 1(c), and bent. At the same time, the printed film 2 was fired to form an increased reflection film. Such a functional thin film has an optical thickness of 700 Å (refractive index n=2
．． 0 (6328 Å), actual film thickness d=350 Å
)Met. These glass plates 1 and 3 were laminated and vitrified via a polyvinyl butyral film as shown in FIG. 1(d) to form a HUD combiner.

The side on which the functional thin film of such a combiner is formed is the inside of the vehicle, and the transmittance of the functional thin film portion and the reflection of the functional thin film surface on the inside of the vehicle due to the functional thin film portion (incidence angle of 0°)
) are shown in Figure 2. Further, FIG. 3 shows the reflection characteristics of the functional thin film surface on the inside of the vehicle at an incident angle of 65° in the functional thin film portion. The formed HUD combiner had a good appearance without haze or optical distortion.

[0028]

According to the present invention, it is possible to produce glass with a functional thin film, which has a functional thin film on a small portion of a large glass substrate, without requiring complicated processes such as etching.

In particular, the viscosity is between 20 and 120 cP,
Metal alkoxide is 2.0 to 8.0 in terms of metal oxide.
The leveling of the thin film function forming liquid obtained by flexographic printing of the thin film function forming liquid containing % by weight is extremely fast in a few seconds, and by baking it, the leveling of the thin film function forming liquid containing % by weight is favorable in terms of uniformity and appearance, and it also has excellent chemical and mechanical durability. A suitable thin-film functional glass can be efficiently produced.

[0030] Furthermore, by simultaneously performing the formation of a functional thin film by firing and the bending and/or strengthening process, the manufacturing process is simplified, productivity is improved, and manufacturing costs are reduced. Combiners can be produced efficiently.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the production process of the method for producing glass with a functional thin film according to the present invention.

FIG. 2 is a graph showing the spectrum of the functional thin film portion of the HUD combiner in Example 1.

FIG. 3 is a graph showing the film surface reflection characteristics at 65° incidence in the functional thin film portion of the HUD combiner of Example 1.

FIG. 4 is a sectional view of an example of a flatbed flexo printing machine used in the present invention.

[Explanation of symbols]

1 Glass plate 2 Printed film (functional thin film) 3 Glass plate 4 Plastic interlayer film

Claims (7)

[Claims] Claim 1: (a) forming a printed film by flexographic printing a functional thin film forming liquid containing a metal oxide raw material on a predetermined portion of a glass plate; (b) bending the glass plate of (a); , and/or
A method for producing glass with a functional thin film, comprising the step of heating the printed film for strengthening and simultaneously baking the printed film to form a functional thin film containing a metal oxide as a main component. 2. The method for producing glass with a functional thin film according to claim 1, wherein a liquid containing a metal alkoxide and having a viscosity of 20 to 120 cP is used as the liquid for forming the functional thin film. 3. The glass with a functional thin film according to claim 1 or 2, wherein a liquid containing 2.0 to 8.0% by weight of metal alkoxide in terms of metal oxide is used as the liquid for forming the functional thin film. manufacturing method. 4. A claim characterized in that after a printed film is formed on a glass plate by flexographic printing, the printed film is dried at a temperature of 50 to 200°C before being subjected to heating and bending and/or reinforcing processing. Item 3. A method for producing a glass with a functional thin film according to any one of Items 1 to 3. 5. Any one of claims 1 to 4, wherein the glass plate is subjected to bending processing, or bending processing and strengthening processing so that the surface of the glass plate on which the printed film is formed is concave. A method for producing glass with a functional thin film according to item 1. 6. After performing bending and/or strengthening processing and simultaneously firing the printed film to form a functional thin film, a glass plate having such a functional thin film and another glass plate are bonded to each other. 6. The method for producing glass with a functional thin film according to any one of claims 1 to 5, characterized in that the glass is bonded via a plastic interlayer so that the surface on which is formed is exposed. Claim 7: The optical thickness of the functional thin film after firing is 400~
7. A method for manufacturing a combiner for a head-up display using the method for manufacturing glass with a functional thin film according to any one of claims 1 to 6, wherein the thickness is 2300 Å.