JPH10167773A - Production of laminated glass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently produce bubble-free laminated glass. SOLUTION: A plastic sheet having both embossed surfaces in a center line average height (Ra) of 0.01-2.0μm with a peak count (Pc) of 5-500/8mm is placed between 2 or more sheets of glass plates. Then, they are primarily heated at such a temperature at which the tensile modules of elasticity of the surface of the plastic sheet gives the value of 7×10<8> -1×10<6> Pa, pressed with at least one couple of nip rollers at a linear pressure of 5-200kgf/cm and secondary heat at such a temperature at which the shear modules of elasticity of the plastic sheet becomes 5×10<5> -5×10<3> Pa.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a laminated glass and, more particularly, to a method for efficiently producing a laminated glass containing no bubbles.

[0002]

2. Description of the Related Art Conventionally, in the production of laminated glass, a plastic sheet is interposed between the laminated surfaces of the glass for adhesion or reinforcement. It is necessary to discharge it, so it is manufactured by adding various ideas,
It had to be an inefficient way.

[0003] For example, (1) a sheet in which a sheet is sandwiched between two glass plates is placed in a rubber bag and depressurized, and preheating is performed with the rubber bag in a state where pressure is applied from above and below the glass plate. After leaving some air bubbles in the sheet or at the interface between the sheet and the glass, the laminated glass is sealed in a high-temperature and high-pressure container, and the remaining air is dissolved in the sheet or the adhesive to remove the air bubbles. (2) After passing a sheet sandwiched between two glass plates through a heating furnace, sandwiched between nip rolls to squeeze out residual air at the interface between the sheet and the glass, and then heat the laminated glass to a high temperature. There is a method of enclosing in a high-pressure container and performing the main heating and pressurization in a high-temperature and high-pressure container to form a laminated glass.

[0004] In any case, these methods are of the batch type, are inefficient, and require large-scale equipment. Nevertheless, since there is a lot of air to be dissolved in the sheet or the adhesive by the high-temperature and high-pressure treatment, the heat applied after the production of the laminated glass causes it to be dissolved and re-foamed, often deteriorating the appearance and safety.

[0005]

Means for Solving the Problems The inventors of the present invention have found optimum pressure and heating conditions for squeezing out bubbles, and produced a laminated glass free of bubbles even by a continuous method which is more efficient than the conventional batch method. Completed a possible method.

That is, the gist of the present invention is that both surfaces have a center line average roughness Ra of 0.01 to 2.0 μm and a peak number Pc of 5 to 5 μm.
A plastic sheet having an embossing of 500/8 mm is sandwiched between two or more glass plates, and the tensile elastic modulus of the surface of the plastic sheet is 7 × 10 ⁸ to 1 × 10 ⁶ P
After the primary heating at the temperature of a, the linear pressure is 5 to 200 kgf.
/ Cm pressure with at least one pair of nip rolls and then the plastic sheet has a shear modulus of 5 × 1
The present invention provides a method for producing a laminated glass, wherein the secondary heating is performed at a temperature of from 0 ^{5 to} 5 × 10 ³ Pa. When an adhesive layer is provided on a plastic sheet, an emboss is formed on the surface of the adhesive layer.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
An emboss is formed on the surface of a plastic sheet sandwiched between two or more glass plates as an adhesive layer or a reinforcing layer to facilitate degassing. The optimum range of the emboss shape varies depending on the material of the plastic sheet, but in general, the center line average roughness Ra is 0.01 to 2.0 μm, and the number of peaks Pc is 5 to 5.
The range is 500 (pieces / 8 mm).

If Ra is less than 0.01 μm, when bonding with glass, the top of the embossed hill of the sheet is melted quickly by heat, so that the air between the sheet and the glass cannot be completely removed and bubbles remain. Will be. If it exceeds 2.0 μm, the peak of the emboss is too high, and in the case of heating and melting, the air is trapped at the foot of the peak and bubbles remain.

If the number of peaks Pc is less than 5, the interval between the convex portions of the sheet is too wide, and the concave portions come into contact with the glass at an early stage of heating and melting, so that bubbles remain at irregular positions. Bad appearance. If Pc exceeds 500, the interval between the projections is too small, and bubbles are trapped between the projections in the process of melting the projections by heating, resulting in poor appearance.

When an adhesive layer is provided on the surface of a plastic sheet, the above-mentioned emboss may be formed on the surface of the adhesive layer.

Here, the center line average roughness Ra is JIS B
0601 is defined as the arithmetic center line average roughness Ra, and the number of peaks Pc is measured by the method described in the following example.

After the embossed plastic sheet is sandwiched between two or more glass plates, the surface of the plastic sheet has a tensile modulus of elasticity of 7 × 10 ⁸ to 1 × 1.
0 primary heating at ⁶ Pa become temperature. The temperature at which the tensile modulus is in this range is the softening temperature that does not lead to melting,
The sheet is easily deformable, and the emboss is in a state where it can be easily deformed into contact with the glass or the adjacent embossed protrusion.

The tensile modulus of the sheet surface is 1 × 10 ⁶ Pa
If it is less than 1, melting (deformation) of the sheet proceeds, and the embossed projections adhere to the glass projections, trapping air, and remain as bubbles. Further, in the range exceeding 7 × 10 ⁸ Pa, the softening of the sheet is insufficient, the deformation of the embossed projection does not occur, and the glass and the sheet cannot be temporarily attached.

Next, the primary heated laminated glass is subjected to a linear pressure of 5
Press with at least one pair of nip rolls at a pressure of ~ 200 kgf / cm. Thereby, the softened sheet is deformed by pressure, the top of the emboss comes into contact with the glass plate, and the air bubbles between the glass and the sheet are gradually squeezed out from the portion that has passed the nip roll toward the non-passing portion, and the glass and the The sheets are brought into close contact under reduced pressure.

That is, by setting the sheet surface temperature within the above range and sequentially applying pressure from one end with an appropriate pressure, a reduced pressure state in which bubbles are sufficiently squeezed out can be obtained even under normal pressure without using a pressure reducing device. .

As the nip roll, a rubber roll whose surface is at least made of a rubber material is suitable. The nip roll passing speed is not particularly limited.
m / min.

Next, secondary heating is performed at a temperature at which the shear modulus of the plastic sheet is 5 × 10 ^{5 to} 5 × 10 ³ Pa. This range is a range in which the melt deformation occurs, and is for sufficiently bonding the embossed portion that is insufficiently bonded in the previous stage to each other or to the glass.

When the shear modulus is less than 5 × 10 ³ Pa, the molten sheet flows out of the two glass end faces,
The specified thickness cannot be obtained, and in some cases, the sheet is thermally decomposed and discolored, resulting in poor appearance.

In the range of 5 × 10 ⁵ Pa or more, the unmelted portion of the sheet is insufficiently melted, and the unmelted portion of the sheet remains, resulting in insufficient adhesive strength or a spot pattern, which causes poor appearance. The heating at this stage can be performed in a hot-air heating furnace or the like, and there is no need to apply pressure, which is advantageous in terms of equipment.

By the above steps, a laminated glass containing no air bubbles can be obtained. However, for the purpose of further increasing the transparency, heating and pressurization in a high-temperature and high-pressure container (autoclave) for several minutes to several tens minutes can be performed. .

In the conventional method, even if an autoclave is used, it is difficult to sufficiently deaerate at the previous stage, so there is a limit to dissolving the remaining air in the adhesive to make the air bubbles inconspicuous. The appearance is difficult to obtain, and even if a good appearance is obtained temporarily, it often re-foams due to the heat applied later. On the other hand, according to the method of the present invention, when an autoclave or the like is used, a laminated glass having an extremely good appearance is obtained, and there is no fear of refoaming.

Further, as the plastic sheet in the method of the present invention, various materials such as fluororesin and polyvinyl butyral can be used. As described above, these sheets have important surface characteristics, but need not be a single layer, and may be a laminated sheet containing a polyester film or the like as an intermediate layer.

[0023]

【Example】

(Examples 1 to 5) A fluororesin composed of 40% by weight of vinylidene fluoride, 40% by weight of tetrafluoroethylene and 20% by weight of hexafluoropropylene was melt-extruded to form a sheet having a thickness of 200 μm, and embossed on the sheet surface with various rolls. Processed.

Primary heating at room temperature 15 ° C (no particular heating)
Then, pressure was applied by a nip roll at a linear pressure of 40 kgf / cm and at a speed of 0.5 m / min, and then secondary heating was performed by passing through a hot-air oven at 150 ° C.

Center line average roughness (Ra) and number of peaks (Pc) of the obtained embossed sheet, tensile modulus at the time of primary heating, shear modulus at the temperature of secondary heating,
The appearance of the laminated glass after pressurization and after secondary heating was observed, and the results are summarized in Table 1.

The test evaluation method for each item is as follows.

(1) Center line average roughness (Ra) and number of peaks (Pc) Stylus type surface roughness meter (SE-3FK manufactured by Kosaka Laboratory Co., Ltd.)
The center line average roughness was measured at an arbitrary 8 mm interval on the surface of the plastic sheet or the adhesive under the conditions of a needle tip diameter of 2 μm, a needle load of 70 mg, and a cutoff value of 0.8 mm.

As shown in FIG. 1, the number of peaks (Pc) is 2 at a distance of ± y (mm) from the center line of the roughness curve obtained above.
One parallel line was drawn, and one mountain was counted from the line of -y to the line of + y to the line of -y again. y (mm) is 0.
00005.

(2) Tensile modulus at primary heating temperature An amplitude width of 0.5% strain, 1
The measurement temperature was changed while the plastic sheet was expanded and contracted at a cycle of Hz, and the storage elastic modulus at the temperature at the time of primary heating was measured.

When an adhesive layer was provided on a plastic sheet, the adhesive layer was separately formed into a sheet, and the measurement was performed under the same conditions.

(3) Shear modulus at secondary heating temperature Torsion angle of 0.5% strain by dynamic viscoelasticity measuring device, 1
The measurement temperature was changed while twisting the entire plastic sheet (when there is an adhesive layer, together with the adhesive layer) at a cycle of Hz, and the storage elastic modulus at the temperature during the secondary heating was measured.

Example 6 A fluororesin consisting of 40% by weight of vinylidene fluoride, 40% by weight of tetrafluoroethylene and 20% by weight of hexafluoropropylene was prepared in Example 1.
A sheet having a thickness of 200 μm was formed in the same manner as in the above. Subsequently, an acrylic adhesive was applied to both sides and dried to form an adhesive film having a thickness of 1 μm, and the adhesive was reheated to soften the adhesive surface.
Embossing was performed with an embossing roll to prepare an embossed sheet with an adhesive layer.

This sheet is sandwiched between two sheets of glass and heated at 50 ° C.
, And passed through a nip roll at a linear pressure of 40 kg / cm and a speed of 0.5 m / min, and then passed through a heating furnace at 150 ° C. Table 1 shows the results.

Example 7 A commercially available polyvinyl butyral sheet having a thickness of 380 μm was sandwiched between two embossed polyester films, heated to 160 ° C. by a hot press method, and the polyester film was peeled off. 230μ thick embossed surface
m of polyvinyl butyral sheet was obtained.

Using this sheet, a primary heating temperature of 30
A laminated glass was produced under the same conditions as in Example 5 except that the secondary heating temperature was set to 120 ° C.

(Comparative Example 1) A fluororesin sheet was produced under the same conditions as in Example 1, and a laminated glass was produced under the same conditions as in Example 1 except that primary heating was performed at a temperature of 120 ° C.

Comparative Example 2 A laminated glass was produced under the same conditions as in Example 6, except that the primary heating was changed to 15 ° C.

Comparative Example 3 A laminated glass was produced under the same conditions as in Example 1 except that the secondary heating temperature was changed to 110 ° C.

Comparative Example 4 A laminated glass was produced under the same conditions as in Example 1 except that the secondary heating temperature was changed to 250 ° C.

Comparative Examples 5 to 8 Embossed fluororesin sheets shown in Table 1 were produced, and laminated glass was produced under the same conditions as in Example 1.

(Comparative Example 9) Using the sheet of Example 1,
The primary heating was performed at room temperature of 15 ° C. (particularly without heating), and then the pressure was increased at a linear pressure of 3 kg / cm and a speed of 0.5 mm / min.
At this stage, there was no adhesion at all, and the effects of the primary heating and pressing were not observed, so the subsequent work was stopped.

[0042]

[Table 1]

As is evident from the results shown in Table 1, under the conditions of the examples according to the method of the present invention, a laminated glass having a good appearance was obtained, and there was no problem in production. On the other hand, under the conditions of the comparative example, there were problems such as air bubbles remaining, the embossed pattern of the sheet remaining in the final product, and the melted sheet flowing out from the glass end face and overflowing, and was not satisfactory.

[0044]

According to the method of the present invention, the plastic sheet is subjected to primary heating at a temperature at which the tensile modulus of the plastic sheet becomes 7 × 10 ⁸ to 1 × 10 ⁶ Pa, and then to a linear pressure of 5 to 200 kgf / c.
m and at least one pair of nip rolls, then the plastic sheet has a shear modulus of 5 × 10 ⁵ to
By secondary heating at a temperature of 5 × 10 ³ Pa,
A high-quality laminated glass without bubbles can be obtained by an efficient continuous method without requiring excessive pressure and time.

When the quality is to be further improved by using an autoclave or the like at last, there is no danger of re-foaming later because the residual air is extremely small.

[Brief description of the drawings]

FIG. 1 is a view for explaining a method for measuring the number of embossed peaks.

Claims (2)

[Claims] 1. Both surfaces have a center line average roughness Ra of 0.01.
An embossed plastic sheet having a thickness of 2.0 μm and a peak number Pc of 5 to 500 pieces / 8 mm is sandwiched between two or more glass plates, and the tensile elastic modulus of the surface of the plastic sheet is 7 × 10 ⁸ to 1 × 10 ^6. After the primary heating at a temperature of Pa, a pressure of a linear pressure of 5 to 200 kgf / cm is applied by at least one pair of nip rolls, and then the shear modulus of the plastic sheet is 5 × 10 ^{5 to} 5 × 10 ³ Pa. A method for producing a laminated glass, comprising secondary heating at a predetermined temperature. 2. The method for producing laminated glass according to claim 1, wherein an adhesive layer is provided on the plastic sheet, and a plastic sheet having an embossed surface on the surface of the adhesive layer is used.