JPH09235139A - Flexural forming of plate glass equipped with coating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for carrying out flexural forming of a plate glass equipped with a coating film, capable of heating the plate glass to the softening temperature while keeping the plate glass in plane state, accurately carrying out press forming thereby and excellent in quality of reflection strain. SOLUTION: A plate glass 2 is heated to a softening temperature while horizontally carrying in a state in which coating film 4a is upwardly kept. Although the internal elastic force of the plate glass 2 is made smaller than residual shrinkage stress F1 and F1 of the coating film 4a thereby, the residual shrinkage stress F1 and F1 of the coating film are cancelled by own weight of the plate glass. The plate glass 2 equipped with the coating film 4a is heated to softening temperature while horizontally being carried. In this case, heating temperature T1 of the surface to which coating film 4a is applied is kept higher than a heating temperature T2 of other face. Consequently, thermal expansion amount of the face on the coating film 4a becomes larger than thermal expansion amount of other face and residual contact stress F1 and F1 of the coating film are cancelled.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for bending a plate glass with a coating film.

[0002]

2. Description of the Related Art Some automobile window glasses have antiglare properties and antireflection properties. Generally, these window glasses can be obtained by applying a coating film on the surface, and there is a sol-gel method as an example of a method for forming the coating film. Hereinafter, a method for bending a plate glass with a coating film by a sol-gel method will be described.

FIGS. 8 (a) to 8 (e) are process explanatory diagrams of a method for bending a plate glass with a coating film (first conventional example). (A) shows a state in which the plate glass 100 is vertically suspended and dipped in the coating liquid 102 in the liquid tank. A mask 101 is applied to the back surface of the plate glass 100 in advance. (B) shows a state in which the plate glass 100 is pulled up from the coating liquid 102 and the mask 101 is removed. Plate glass 100 has coating liquid 10 only on the surface.
2 is applied. (C) shows a state in which the coating film 102a is formed on the plate glass 100. 250 ° C
By baking the coating liquid 102, the coating film 102a is formed and thermally contracted, and residual contraction stresses F ₁ and F ₁ are generated. In this case, since the plate glass 100 in the unsoftened state has an internal elastic stress larger than the residual shrinkage stresses F ₁ and F ₁ , the plate glass 100 does not have to be bent.

(D) shows a state in which the plate glass 100 is heated to the softening temperature. By heating the plate glass 100 to the softening temperature (about 570 to 700 ° C.) in the heating furnace 106, the internal elastic force of the plate glass 100 is increased by the coating film 10.
It becomes smaller than the residual shrinkage stresses F ₁ and F _{1 of} 2a.
00 is plastically deformed into a curved shape. The residual shrinkage stresses F ₁ and F ₁ increase as the heating temperature rises from 250 ° C. and reach a maximum value at about 450 ° C. (E) shows a state in which the plate glass 100 plastically deformed into a curved shape is press-molded. The plate glass 10 is pressed by the left and right press dies 108a and 108b.
0 is press-molded to manufacture a curved window glass.

9 (a) to 9 (f) are process explanatory views of a method for bending a plate glass with a coating film (second conventional example). The steps (a) to (c) are shown in FIGS.
Since it is the same as (c), the description is omitted.

(D) is a bed 11 for transporting the plate glass 100.
It shows a state in which it is placed above 0 and heated to the softening temperature. In this case, the reason why the plate glass 100 is arranged on the transport bed 110 with the coating film 102a facing downward is as follows.
It is as follows. The window glass of a car is attached with the concave surface facing the interior. When forming the coating film on the window glass, the coating film is formed on the inner surface (that is, the concave surface) of the window glass in order to prevent damage or the like. When manufacturing a window glass, the curved window glass is cooled while being conveyed by rollers, but in this case, the concave surface of the window glass is directed downward in order to stabilize the conveying attitude of the window glass. For the reasons (1) to (3), when the plate glass with a coating film is formed by bending, the coating film 102a applied to the plate glass 100 is generally faced downward. Coating film 10
2a faces downward, so that the glass plate 100 is not supported by the transport bed 110 in order to prevent the coating film 102a from being damaged.
Is heated to the softening temperature in the heating furnace 109 in a floating state. Thus, the internal elastic forces of the glass sheet is smaller than the residual shrinkage stress F _1, F ₁ of the coating film, plate glass is plastically deformed into a curved shape in residual shrinkage stress F _1, F ₁ of the coating film.

(E) is plate glass 1 plastically deformed into a curved shape
00 shows a press-molded state, and (f) shows a state in which the curved plate glass 100 is cooled while being conveyed by the conveying rollers 111. Curved sheet glass 100
Since the convex surface of the plate glass is upward, the peripheral edge of the plate glass 100 comes into contact with the transfer rollers 111 and so that the transfer posture of the plate glass 100 during transfer is stabilized.

[0008]

In the prior art shown in FIGS. 8 and 9, the curved plate glass 100 is formed by pressing the molds 108a, 1a.
08b is for further curved molding. However, when the plate glass 100 after pressing was examined, it was found that the finished shape varied or had a large error from the expected shape. In addition, there is a problem that the quality of the reflection distortion of the curved glass after press molding is inferior. Generally, press mold 1
Nos. 08a and 108b are suitable for curve-forming flat or flat sheet glass having a constant R heated to the softening temperature, and as in the above-described conventional example, the residual shrinkage stresses F ₁ and F ₁ of the coating film cause "curvature". It can be presumed that it is not suitable for the curved forming of "a flat glass". Action of residual shrinkage stresses F ₁ and F ₁ of the coating film and press dies 108a and 108b
It is thought that this is because the effects of the above interfere with each other. Also,
When the plate glass 100 is floated in FIG. 9D, the plate glass 100 bends downward, and therefore, when the plate glass 100 is floated and heated and transferred under the same conditions as usual, both edges of the plate glass 100 rub against the transfer bed 110. Therefore, the plate glass 1 is more than usual.
It is necessary to raise 00.

Therefore, an object of the present invention is to flatten a sheet glass before press forming to produce a curved sheet glass having excellent reflection distortion quality.

[0010]

In order to solve the above-mentioned problems, the first aspect of the present invention is to apply a heat-shrinkable coating solution to the upper surface of a horizontal plate glass, and to heat the coating solution on the upper surface. It comprises a step of forming a film, a step of heating the plate glass to at least a softening temperature, and a step of bending the plate glass with a molding die.

By firing the coating liquid, residual shrinkage stress is generated in the coating film, which tends to bend the plate glass into a curved shape. Then, the plate glass is heated upward to the softening temperature while being horizontally conveyed with the coating film facing upward. Thereby, the internal elastic force of the plate glass becomes smaller than the residual shrinkage stress of the coating film, but the residual shrinkage stress of the coating film can be canceled by the weight of the plate glass. Therefore, the plate glass can be heated to the softening temperature while being kept flat.

According to a second aspect of the present invention, a step of applying a heat-shrinkable coating solution to one side of a horizontal plate glass, a step of heating the coating solution to form a film, and at least a softening point of the other side of the plate glass. And heating one side to a temperature higher than the other side, and bending the plate glass with a forming die.

By firing the coating liquid, residual shrinkage stress that tends to bend the plate glass into a curved shape is generated in the coating film. Then, the plate glass coated with the coating film is heated to the softening temperature while being horizontally conveyed with the coating film facing upward. In this case, the heating temperature of one side coated with the coating film is set higher than the heating temperature of the other side. Therefore, the amount of thermal expansion on one side where the coating film is applied becomes larger than the amount of thermal expansion on the other side, and a stress that tends to bend the sheet glass is generated, and this stress causes the residual shrinkage stress of the coating film. Can be offset.
Therefore, the plate glass can be heated to the softening temperature while being kept flat.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings. The drawings should be viewed in the direction of reference numerals.

FIG. 1 is a side view showing an apparatus for bending sheet glass with a coating film according to the present invention. The bending apparatus 1 for a plate glass with a coating film comprises a coating means 3 for coating the plate glass 2 with a coating liquid, a drying means 8 for baking the coating liquid to form a coating film 4a, and a heating furnace for heating the plate glass 2 to a softening temperature. 10, upper and lower press dies 15a and 15b for press-molding the plate glass 2 softened in the heating furnace 10, and conveying rollers 20a, 20b and 20c for conveying the press-molded plate glass 2.
Conveying means 1 for loading and unloading the plate glass 2 into the heating furnace 10.
1 will be described later. The coating means 4 may be a dipping method or a gravure coating method. The coating liquid 4 may be baked in the heating furnace 10 without using the drying means 8.

First Embodiment; FIGS. 2 (a) to 2 (f) are process explanatory views of a method for bending a plate glass with a coating film according to the present invention (first embodiment). (A) is a coating liquid 4 in a liquid tank 6 in which a plate glass 2 is suspended vertically.
The state of dipping is shown. In this case, plate glass 2
The mask 6a is applied to the back surface of the coating liquid 4 in the liquid tank 6
Dip inside. (B) shows a state in which the plate glass 2 is pulled up from the coating liquid 4 and the mask 6a is removed. The plate glass 2 is in a state in which the coating liquid 4 is applied only to the surface.

(C) is a coating film 4a on the plate glass 2.
A film-formed state is shown. Coating film 4a at 250 ° C
By baking, the coating film 4a is thermally contracted, and residual contraction stresses F ₁ and F ₁ are generated in the coating film 4a. In this case, since the plate glass 2 is in an unsoftened state, the internal elastic stress of the plate glass 2 is larger than the residual shrinkage stresses F ₁ and F ₁ , and the plate glass 2 is kept flat.

(D) shows a state in which the plate glass 2 is heated to the softening temperature. The glass plate 2 is placed on the conveying rollers 11a ... (Conveying means 11; see FIG. 1) with the coating film 4a facing upward, and the conveying rollers 11a ... convey the inside of the heating furnace 10 to the softening temperature (570 to 700 ° C.). To heat. As a result, the internal elastic force of the plate glass 2 becomes smaller than the residual shrinkage stresses F ₁ and F _{1 of the} coating film 4a, and the plate glass 2 tries to bend into a curved shape, but the weights W ₁ and W _{1 of the} plate glass 2 act. To cancel the residual shrinkage stresses F ₁ and F ₁ .
Thereby, the plate glass 2 becomes flat. The residual shrinkage stresses F ₁ and F ₁ of the coating film 4a increase as the heating temperature rises from 250 ° C. and reach a maximum value at about 450 ° C.

When the plate glass 2 is transported by the transport rollers 11a, the same effect can be obtained by arranging the coating film 4a downward, but in this case, the coating film 4a.
Are rubbed against the surface of the transport rollers 11a, which damages the coating film 4a, which is not preferable.

(E) shows a state in which the flat plate glass 2 is press-molded. The flat plate glass 2 is placed on the upper and lower press dies 15
Since press molding is performed with a and 15b, the finishing accuracy becomes good. (F) is a conveyance roller 2 which is a curved plate glass 2
The state of cooling while being conveyed at 0, 20b, and 20c is shown. Since the bent glass sheet 2 has a convex surface on the lower side,
The three-divided conveying rollers 20a, 20b, 20c are arranged along the convex surface of the plate glass 2 to convey the plate glass 2 in a stable posture.

Second Embodiment; FIGS. 3 (a) to 3 (e) are process explanatory views of a method for bending a plate glass with a coating film according to the present invention (second embodiment). (A) shows a state in which the coating liquid 4 is applied to the upper surface of the plate glass 2 during horizontal conveyance. The plate glass 2 is horizontally conveyed by the conveying rollers 7, and the coating liquid 4 is applied to the upper surface of the plate glass 2 by the gravure coating method during the conveyance. (B) shows a state in which the coating film 4 a is formed on the plate glass 2. 2
By baking the coating film 4a at 50 ° C., residual shrinkage stresses F ₁ and F ₁ are generated in the coating film 4a. At this time, since the plate glass 2 is in an unsoftened state, the internal elastic stress of the plate glass 2 causes the residual shrinkage stress F ₁ of the coating film 4 a,
Keep the plate glass flatter than F ₁ .

(C) to (e) are the same as (d) to (f) in FIG. That is, (c) shows a state in which the plate glass 2 is heated to the softening temperature. The plate glass 2 is placed on the conveying rollers 11a with the coating film 4a facing upward, and is heated to the softening temperature (570 to 700 ° C.) while being conveyed in the heating furnace 10 by the conveying rollers 11a. As a result, the internal elastic force of the plate glass 2 becomes smaller than the residual shrinkage stresses F ₁ and F _{1 of the} coating film 4a, and the plate glass 2 tries to bend into a curved shape, but the weights W ₁ and W _{1 of the} plate glass 2 act. To cancel the residual shrinkage stresses F ₁ and F ₁ . Thereby, the plate glass 2 is kept flat. Residual shrinkage stress F of coating film 4a
₁ , F ₁ increases as the heating temperature rises from 250 ° C., and reaches a maximum value at about 450 ° C.

(D) shows a state where the flat plate glass 2 is press-molded. The flat plate glass 2 is placed on the upper and lower press dies 15
Since press molding is performed with a and 15b, the finishing accuracy becomes good. (E) is a conveyance roller 20 for the curved plate glass 2
The state which cools, conveying with a, 20b, and 20c is shown. Since the bent glass sheet 2 has a convex surface on the lower side,
The three-divided conveying rollers 20a, 20b, 20c are arranged along the convex surface of the plate glass 2 to convey the plate glass 2 in a stable posture.

Third Embodiment; FIGS. 4 (a) to 4 (f) are process explanatory views of a method for bending a plate glass with a coating film according to the present invention (third embodiment). (A)
(C) are the same as (a) to (c) of FIG. That is, (a) shows a state in which the plate glass 2 is vertically suspended and dipped in the coating liquid 4 in the liquid tank 6. In this case, the back surface of the plate glass 2 is covered with a mask 6a and dipped in the coating liquid 4 in the liquid tank 6. (B) shows a state in which the plate glass 2 is pulled up from the coating liquid 4 and the mask 6 is removed. The plate glass 2 is in a state in which the coating liquid 4 is applied only to the surface.

(C) is a coating film 4a on the plate glass 2.
A film-formed state is shown. Coating film 4a at 250 ° C
By baking, the coating film 4a is thermally contracted, and residual contraction stresses F ₁ and F ₁ are generated in the coating film 4a. In this case, since the plate glass 2 is in an unsoftened state, the internal elastic stress of the plate glass 2 is larger than the residual shrinkage stresses F ₁ and F ₁ , and the plate glass 2 is kept flat.

(D) is a transfer bed 11b (transfer means 1)
1; see FIG. 1), showing a state in which the plate glass 2 floating above is heated to the softening temperature. While the coating film 4a faces upward, the plate glass 2 is floated above the transfer bed 11b, and the upper surface of the plate glass 2 is moved to T while being transferred in the heating furnace 10.
Heat to ₁ and lower surface to T ₂ . The heating temperatures T ₁ and T ₂ satisfy the relationship of T ₂ <T ₁ (where T ₂ is a temperature equal to or higher than the softening temperature). Therefore, the thermal expansion amount of the upper surface of the plate glass 2 becomes larger than the thermal expansion amount of the lower surface thereof, stresses F ₂ and F ₂ are generated on the upper surface side of the plate glass 2, and the residual contraction stress of the coating film 4a is generated by the stresses F ₂ and F _2. The flat glass 2 is kept flat by offsetting F ₁ and F ₁ . The residual shrinkage stresses F ₁ and F ₁ of the coating film 4a increase as the heating temperature rises and reach a maximum value at about 450 ° C.

(E) and (f) are the same as (d) and (e) in FIG. That is, (e) shows a state in which the flat plate glass 2 is press-molded. Since the flat plate glass 2 is press-molded by the upper and lower press dies 15a and 15b, the finishing accuracy becomes good. (F) shows a state in which the curved glass sheet 2 is cooled while being conveyed by the conveying rollers 20a, 20b, 20c. Since the bent glass sheet 2 has a convex surface on the lower side, it is divided into three conveyance rollers 20a, 20b, 20c.
Are arranged along the convex surface of the plate glass 2 to convey the plate glass 2 in a stable posture.

Fourth Embodiment; FIG. 4 of the third embodiment.
Instead of (d), the same effect as in the third embodiment can be obtained by disposing the plate glass 2 so that the coating film 4a faces downward. In this case, the upper surface of the plate glass 2 is heated to T ₂ and the lower surface is heated to T ₁ . Heating temperature T
₁ and T ₂ satisfy the relationship of T ₂ <T ₁ (where T ₂ is a temperature equal to or higher than the softening temperature).

Fifth Embodiment: FIG. 4 of the third embodiment.
Instead of (d), the same effect can be obtained by placing the plate glass 2 with the coating film 4a facing upward on the transport rollers 11a ... (See FIG. 2D). In this case, the own weights W ₁ and W _{1 of} the plate glass 2 (see FIG. 2D) act to cancel the residual shrinkage stresses F ₁ and F ₁ of the coating film 4a, so that the plate glass 2 is kept flat more efficiently. .

Sixth Embodiment; FIGS. 5 (a) to 5 (e) are process explanatory views of a method for bending a plate glass with a coating film according to the present invention (sixth embodiment). In addition,
(A) and (b) are the same as (a) and (b) of FIG.
(C) to (e) are the same as (d) to (f) in FIG.
That is, (a) shows a state in which the coating liquid 4 is applied to the upper surface of the plate glass 2 during horizontal conveyance. Conveyor roller 7 ...
The plate glass 2 is conveyed horizontally with the plate glass 2 during this conveyance.
The coating liquid 4 is applied to the upper surface of the substrate by a gravure coating method. (B) shows a state in which the coating film 4 a is formed on the plate glass 2. By baking the coating film 4a at 250 ° C., residual shrinkage stresses F ₁ and F ₁ are generated in the coating film 4a. At this time, since the plate glass 2 is in a non-softened state, the internal elastic stress of the plate glass 2 is increased by the coating film 4.
The plate glass is kept flat, which is larger than the residual shrinkage stresses F ₁ and F _{1 of a} .

(C) shows a state in which the plate glass 2 floating on the transfer bed 11b is heated to the softening temperature. The glass plate 2 is transferred to the transport bed 11 with the coating film 4a facing upward.
while conveying the heating furnace 10 in a state of being floated above the b while heating the upper surface of the glass sheet 2 to T ₁ heats the lower surface T _2. The heating temperatures T ₁ and T ₂ satisfy the relationship of T ₂ <T ₁ (where T ₂ is a temperature equal to or higher than the softening temperature). Therefore, the thermal expansion amount of the upper surface of the plate glass 2 becomes larger than the thermal expansion amount of the lower surface thereof, stresses F ₂ and F ₂ are generated on the upper surface side of the plate glass 2, and the residual contraction stress of the coating film 4a is generated by the stresses F ₂ and F _2. The flat glass 2 is kept flat by offsetting F ₁ and F ₁ . The residual shrinkage stresses F ₁ and F ₁ of the coating film 4a increase as the heating temperature rises and reach a maximum value at about 450 ° C.

(D) shows a state where the flat plate glass 2 is press-molded. The flat plate glass 2 is placed on the upper and lower press dies 15
Since press molding is performed with a and 15b, the finishing accuracy becomes good. (E) is a conveyance roller 20 for the curved plate glass 2
The state which cools, conveying with a, 20b, and 20c is shown. Since the bent glass sheet 2 has a convex surface on the lower side,
The three-divided conveying rollers 20a, 20b, 20c are arranged along the convex surface of the plate glass 2 to convey the plate glass 2 in a stable posture.

[0033]

【Example】

First Example: A plate glass with a three-layer coating film was bent and formed by the procedure of the second embodiment shown in FIGS. 3 (a) to 3 (e). First, the coating liquid A is prepared in the following steps.
To 41.3 g of tetra-n-butoxyzirconium is added 28.0 g of ethyl acetoacetate and stirred for 30 minutes at room temperature to form ethyl zirconium butoxydiacetoacetate. Subsequently, in this zirconium butoxydiacetoacetate ethyl, 423.0 g of butyl cellosolve, 250 g of hexylene glycol, and a pentamer of tetraethoxysilane (product of Colcoat, product name "ethyl silicate 40") 43.0.
g and 0.01 g of hydrochloric acid (5.2 g) are sequentially added, and the mixture is stirred at room temperature for 2 hours to prepare a coating solution A of Example 10. The prepared coating liquid A is a low refractive index coating liquid having a Si / Zr molar ratio of Si / Zr = 8/3.

Next, the coating solution B is prepared in the following steps. Tetra n-butoxy zirconium 164.9g
111.9 g of ethyl acetoacetate are added and stirred for 30 minutes at room temperature to form ethyl zirconium butoxydiacetoacetate. Subsequently, to this ethyl zirconium butoxydiacetoacetate, 425.9 g of butyl cellosolve, 250 g of hexylene glycol, and a pentamer of tetraethoxysilane (produced by Colcoat, product name “ethyl silicate 4
0 ″) 43.0 g and 0.01 N hydrochloric acid 5.2 g are sequentially added and stirred at room temperature for 2 hours to form a coating solution B of Example 10. The prepared coating liquid B is a medium refractive index coating liquid having a Si / Zr molar ratio of Si / Zr 2/3.

FIGS. 6 (a) to 6 (c) are explanatory views for forming a three-layer coating film. This three-layer coating film 18 is formed by the procedure of the second embodiment shown in FIG. (A) shows a state in which the coating A film 18 a is formed on the upper surface of the plate glass 2. Coating A liquid 18a in the process of FIG.
Plate glass 2 (plate thickness 3.
4 mm soda lime glass) is applied to the entire surface on one side, and coating A is applied to the plate glass 2 in the step of FIG. 3 (b).
The solution is dried at 250 ° C. for 30 minutes to form a coating A film 18
a is formed.

(B) shows a state in which the coating B film 18b is formed on the surface of the coating A film 18a. Similar to the coating A film 18a, the coating B film 18b is formed on the surface of the coating A film in the steps of FIGS.

(C) shows a state in which the coating A film 18c is formed on the surface of the coating B film 18b. Similar to the coating B film 18b, the coating A film 18 is formed on the surface of the coating B film 4b in the steps of FIGS.
c is deposited to form the three-layer coating film 18. This three-layer coating film 18 has three layers (glass / A film 4a
/ B film 4b / A film 4c / air) type antireflection film.

Next, in the process of FIG.
Conveying roller 11a with the layer coating film 18 facing upward
, And the plate glass 2 is heated in the heating furnace 10 at a softening temperature (about 570 ° C. to 700 ° C.). As a result, the internal elastic force of the plate glass 2 becomes smaller than the residual shrinkage stresses F ₁ , F _{1 of the} three-layer coating film 18, but the plate glass's own weight W ₁ ,
W ₁ acts to cancel the residual shrinkage stresses F ₁ and F ₁ to keep the plate glass 2 flat. Next, in the step (d), the flat plate glass 2 is press-molded by the upper and lower press dies 15a, 15b, and the plate glass 2 curved in the step (e) is cooled while being conveyed by the conveying rollers 20a, 20b, 20c. .

As a result of inspecting the reflection distortion of the curved glass sheet 2, it was found that the quality of the reflection distortion was excellent and it was in the same state as the plate glass without the three-layer coating film 18.

First Comparative Example: A plate glass with a three-layer coating film was bent by the procedure of the first conventional example shown in FIGS. 8 (a) to 8 (e). First, the steps (a) to (c) are sequentially repeated to form the three-layer coating film 18 (see FIG. 6C). Next, in the step (d), the plate glass 2 is heated to the softening temperature (about 570 to 700 ° C.). As a result, the internal elastic force of the plate glass 2 becomes smaller than the residual shrinkage stresses F ₁ and F _{1 in the} three-layer coating film, and the plate glass 2 is plastically deformed into a curved shape. Next, in the step (e), the plate glass 2 plastically deformed into a curved shape is press-molded. As a result of inspecting this plate glass 2 for the reflection distortion, it was confirmed that the quality of the reflection distortion was inferior to that of the plate glass 2 of the first embodiment.

Second Comparative Example: A curved plate glass with a three-layer coating film was formed by the procedure of the second conventional example shown in FIGS. 9 (a) to 9 (f). First, as in the first comparative example, (a) to (c)
The step 3 is sequentially repeated to form the three-layer coating film 18 (see FIG. 6C). Next, in the step (d), the softening temperature (570 to 570) is applied in a state where the plate glass 2 is floated above the transport bed 110 with the three-layer coating film 18 facing downward.
Heat up to 700 ° C. Therefore, the internal elastic force of the plate glass 2 causes the residual shrinkage stresses F ₁ and F _{1 of the} three-layer coating film 18 to occur.
It becomes smaller and the plate glass 2 is plastically deformed into a curved shape. As a result, the peripheral edge portion of the three-layer coating film 18 rubbed against the transport bed 110 to prevent the transport of the plate glass 2.

Second Example: A plate glass with a two-layer coating film was bent and formed by the procedure of the sixth embodiment shown in FIGS. 5 (a) to 5 (e).

First, the coating liquid C is prepared in the following steps. Tetra n-butoxy zirconium 164.9g
111.9 g of ethyl acetoacetate are added and stirred for 30 minutes at room temperature to form ethyl zirconium butoxydiacetoacetate. Next, to this ethyl zirconium butoxydiacetoacetate, 425.9 g of butyl cellosolve, 250 g of hexylene glycol, and a pentamer of tetraethoxysilane (manufactured by Colcoat, product name “ethyl silicate 40”)
43.0 g and 0.01 N hydrochloric acid 5.2 g were sequentially added, and the mixture was stirred at room temperature for 2 hours to prepare a coating C liquid of Example 11. The prepared coating liquid C is a medium refractive index coating liquid having a Si / Zr molar ratio of Si / Zr 2/3.

Next, the coating liquid D is prepared in the following steps. Acetylacetone 8.9 g and tetraisopropoxy titanium 12.6 g are added to ethyl cellosolve 59.8 g, and the mixture is stirred at 40 ° C. Next, 2.0 g of tetraethoxysilane pentamer and 0.2 g of 0.01N hydrochloric acid are added, and the mixture is stirred at 40 ° C. for 4 hours. Then, 13.5 g of cerium nitrate hexahydrate was added and stirred at 40 ° C. for 2 hours, and then 3 g
Trimethylolpropane triacrylate-6 ethylene oxide unit adduct (TMPTA E06) is added and stirred to prepare coating D liquid of Example 8.
The prepared coating liquid D is a high refractive index coating liquid having a Si / Ti / Ce molar ratio of Si / Ti / Ce = 3/10/7.

FIGS. 7 (a) and 7 (b) are explanatory views for forming a two-layer coating film. This two-layer coating film is formed by the procedure of the sixth embodiment shown in FIG. (A) shows a state in which the coating C film 19 a is formed on the upper surface of the plate glass 2. Coating C liquid applied to the entire surface of one side of plate glass 2 (soda lime glass having a plate thickness of 3.4 mm) by the gravure coating method in the step of FIG. 5 (a), and applied to plate glass 2 in the step of (b) Is dried at 250 ° C. for 30 minutes to form a coating C film 19a.

(B) shows a state in which the coating D film 19b is formed on the surface of the coating C film 19a. Similar to the coating C film 19a, the coating D film 1 is formed on the surface of the coating C film 19a in the steps of FIGS.
9b is formed to form a two-layer coating film 19. This two-layer coating film 19 has two layers (glass 1 / C film 5
a / D film 5b / air) type antireflection film.

Next, in the step (c), the upper surface of the plate glass 2 is transferred to the upper surface of the plate glass 2 while being conveyed in the heating furnace 10 with the two-layer coating film 19 facing upward and the plate glass 2 being floated above the conveying bed 11b. Heat to ₁ and lower surface to T ₂ . The heating temperatures T ₁ and T ₂ satisfy the relationship of T ₂ <T ₁ (where T ₂ is a temperature equal to or higher than the softening temperature). Therefore, the amount of thermal expansion of the upper surface of the plate glass 2 becomes larger than the amount of thermal expansion of the lower surface thereof, stresses F ₂ and F ₂ are generated on the upper surface of the plate glass 2, and the residual shrinkage of the two-layer coating film 19 is caused by the stresses F ₂ and F _2. The stresses F ₁ and F ₁ are canceled to keep the plate glass 2 flat.

Next, in the step (d), the flat plate glass 2 is press-molded by the upper and lower press dies 15a and 15b,
The plate glass 2 curved and formed in the step (e) is conveyed by the conveying roller 2.
Cool while being transported by 0a, 20b, and 20c.

As a result of inspecting the reflection strain of this plate glass 2, the quality of the reflection strain was excellent, and it was in the same state as the plate glass not coated with a coating film.

Third Comparative Example: A curved flat glass with a two-layer coating film was formed by the procedure of the second conventional example shown in FIGS. 8 (a) to 8 (e). First, the steps (a) to (c) are sequentially repeated to form the two-layer coating film 19 (see FIG. 7B). Next, in the step (d), the plate glass 2 is heated to the softening temperature (about 570 to 700 ° C.). As a result, the internal elastic force of the glass sheet 2 becomes smaller than the residual shrinkage stresses F ₁ and F _{1 of the} two-layer coating film 19, and the glass sheet 2 is plastically deformed into a curved shape. Next, in the step (e), the plate glass 2 plastically deformed into a curved shape is press-molded. As a result of inspecting the reflection distortion of this plate glass, it was confirmed that the quality of the reflection distortion was inferior to that of the curved plate glass of the second example.

Fourth Comparative Example: A curved flat glass with a two-layer coating film was formed by the procedure of the second conventional example shown in FIGS. 9 (a) to 9 (f). First, as in the third comparative example, (a) to (c)
The above steps are sequentially repeated to form the two-layer coating film 19 (see FIG. 7B). Next, in the step (d), the softening temperature (570 to 570) is applied with the two-layer coating film 19 facing downward and the plate glass 2 being floated above the transport bed 110.
Heat up to 700 ° C. Therefore, the internal elastic force of the plate glass 2 causes the residual shrinkage stresses F ₁ , F _{1 of the} two-layer coating film 19 to occur.
It becomes smaller and the plate glass 2 is plastically deformed into a curved shape. As a result, the peripheral edge portion of the two-layer coating film 19 rubbed against the transport bed 110 to prevent the transport of the plate glass 2.

[0052]

The present invention has the following effects due to the above configuration. According to the first aspect of the present invention, the residual shrinkage stress that tends to bend the plate glass into a curved shape is generated in the coating film by firing the coating liquid. Then, the plate glass is heated upward to the softening temperature while being horizontally conveyed with the coating film facing upward. Thereby, the internal elastic force of the plate glass becomes smaller than the residual shrinkage stress of the coating film, but the residual shrinkage stress of the coating film can be canceled by the weight of the plate glass. Therefore, since the plate glass can be heated to the softening temperature while being kept flat, press molding can be performed accurately and the quality of the reflection distortion is excellent. Further, since the plate glass can be kept flat, there is no possibility that the plate glass is bent and deformed by the residual shrinkage stress of the coating film and the coating film is rubbed against the transfer bed to hinder the transfer of the plate glass unlike the prior art.

According to the second aspect of the present invention, the residual shrinkage stress that tends to bend the plate glass into a curved shape is generated in the coating film by firing the coating liquid. Then, the plate glass provided with the coating film is heated to the softening temperature while being horizontally conveyed. In this case, the heating temperature of one side coated with the coating film is set higher than the heating temperature of the other side. Therefore, the amount of thermal expansion on one side where the coating film is applied becomes larger than the amount of thermal expansion on the other side, and the stress that tends to bend the plate glass is generated, and this stress causes the residual shrinkage stress of the coating film. Can be offset. Therefore, since it is possible to heat the plate glass to the softening temperature while keeping the plate glass flat, press molding can be performed with high accuracy, and the quality of reflection distortion is excellent. Moreover, the residual shrinkage stress of the coating film does not cause the plate glass to bend and deform, and the coating film does not rub against the transport bed to prevent the transport of the plate glass.

[Brief description of drawings]

FIG. 1 is a side view showing an apparatus for bending a plate glass with a coating film according to the present invention.

FIG. 2 is a process explanatory view of a method for bending a plate glass with a coating film according to the present invention (first embodiment).

FIG. 3 is a process explanatory view of a method for bending a plate glass with a coating film according to the present invention (second embodiment).

FIG. 4 is a process explanatory view of a method for bending a plate glass with a coating film according to the present invention (third embodiment).

FIG. 5 is a process explanatory view of a method for bending a plate glass with a coating film according to the present invention (sixth embodiment).

FIG. 6 is an explanatory view of forming a three-layer coating film according to the present invention.

FIG. 7 is an explanatory view of forming a two-layer coating film according to the present invention.

FIG. 8 is a process explanatory view of a method for bending a plate glass with a coating film (first conventional example).

FIG. 9 is a process explanatory view of a method for bending a plate glass with a coating film (second conventional example).

[Explanation of symbols]

1 ... Bending and shaping device for plate glass with coating film, 2 ...
Plate glass, 4 ... Coating liquid, 4a ... Coating film, 10 ... Heating furnace, 15a ... Upper press mold, 15b ... Lower press mold.

Claims (2)

[Claims] 1. A step of applying a heat-shrinkable coating liquid on the upper surface of a horizontal plate glass, a step of heating the coating liquid on the upper surface to form a film, a step of heating the plate glass to at least a softening temperature, A method of bending a glass sheet with a coating film, which comprises the step of bending the glass sheet with a forming die. 2. A step of applying a heat-shrinkable coating solution to one side of a horizontal plate glass, a step of heating the coating solution to form a film, and heating the other side of the plate glass to at least a softening point. A method for bending a glass sheet with a coating film, which comprises the step of heating one of the one surfaces to a temperature higher than that of the other one, and the step of bending the glass sheet with a molding die.