JPH06321586A - Intermediate membrane for laminated glass - Google Patents

Abstract

PURPOSE:To provide an intermediate membrane for a laminated glass capable of producing laminated glasses not generating partial voids, distortions or peripheral separations even in the case of using glasses having a pair difference. CONSTITUTION:An intermediate membrane is made to have 3 layer structure having an intermediate layer held between both outside layers and the intermediate layer has a viscosity at 140 deg.C larger than that of the both sides. It is preferable that the viscosity of the intermediate layer at 140 deg.C is 6X10-6X10 poise and that of the both sides is 10<4>-10<5> poise. As to a thickness of each layer, it is preferably 200-800mum for the intermediate layer and 50-200mum for both outside layers which contact with glasses.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an interlayer film for laminated glass. More specifically, the present invention relates to an interlayer film which is inserted between two glass plates to form a laminated glass, and more particularly to an interlayer film for laminated glass which is excellent in workability during a laminating process.

[0002]

2. Description of the Related Art Laminated glass is a laminated glass composed of a laminated body in which an intermediate film is inserted between two plate glasses, and has an excellent feature that it has high strength and is not easily broken. It is a safe glass material that does not scatter. Therefore, it is widely used as window glass for transportation equipment such as automobiles and airplanes, and for buildings.

A plasticized polyvinyl butyral resin sheet, a vinyl chloride resin sheet or the like is mainly used as an interlayer film for laminated glass used in the above laminated glass. These sheets are usually sandwiched between two pieces of glass at room temperature, pre-pressed with a press roll or a vacuum bag, and then heated to a temperature of about 140 ° C. while being pressurized by a method such as an autoclave. It is crimped.

In general, the shapes of the two sheets of glass used for laminated glass are almost the same, but some of them are partially distorted. In particular, a glass having a large curvature such as a safety glass for automobiles is likely to have a difference in shape between the two glasses (this is called a pair difference between the glasses). When a laminated glass is produced by using glasses having different shapes, the gap between the two glasses partially widens,
Even after autoclaving, the interlayer film may not flow in that part and voids may occur in that part.

Conventionally, in order to solve such a problem, the fluidity of the intermediate film has been increased by raising the temperature at the time of autoclave, and an intermediate film having high flow characteristics at high temperature has been used. In order to improve the flow characteristics of the interlayer film at high temperature, the molecular weight of the resin used can be lowered,
It is conceivable to increase the amount of plasticizer or to have a structure having pseudoionic crosslinks such as ionomers. Thus, a method has been generally considered to improve the fluidity of the interlayer film at high temperature, in other words, to reduce the viscosity of the interlayer film during autoclave, to solve the above-mentioned problems.

[0006]

However, in the method of lowering the viscosity of the intermediate film during autoclaving as described above, there is a problem that the molten intermediate film during autoclaving protrudes from the periphery of the laminated glass.

Further, when the laminated glass is used in a slanted manner like the windshield of an automobile, even if the voids in the large glass gap can be eliminated by the flow of the interlayer film, the laminated glass in that portion can be eliminated. Since the thickness becomes thicker than the surroundings, there is a case where a perspective defect, that is, a perspective distortion called distortion occurs.
This is because the difference in thickness of laminated glass is 20 μm / 150 m.
It occurs when m or more.

In order to prevent the above-mentioned distortion from occurring, it is necessary to give the intermediate film a rigidity sufficient to correct the distorted glass. For that purpose, the viscosity of the intermediate film during autoclaving is increased to the contrary. As a result, voids may be generated due to insufficient fluidity of the intermediate film as described above, and if there is a pair difference in the peripheral portion of the glass, the peripheral portion may peel off after long-term use.

Therefore, the present invention provides an interlayer film for laminated glass which can produce laminated glass in which voids are not partially generated, distortion is not generated, or peripheral peeling does not occur even when glass having a pair difference is used. The purpose is to provide.

[0010]

Means for Solving the Problems As a result of intensive research for solving the above-mentioned problems, the inventor has an intermediate film having a three-layer structure and keeping the viscosity of a base intermediate layer at a certain value or more. By doing so, the distortion of the glass can be corrected,
Moreover, they have found that the viscosity of the surface layer in contact with the glass can be lowered, and have completed the present invention.

That is, the present invention provides an intermediate film for laminated glass, which has a three-layer structure in which an intermediate layer is sandwiched between both outer layers, and the viscosity of the intermediate layer at 140 ° C. is higher than the viscosity of both outer layers. provide.

The viscosity of the intermediate layer at 140 ° C. is 6 ×
10 ^{4 to} 6 × 10 ⁵ poise, 140 ° C. of both outer layers
The viscosity at is preferably 10 ⁴ to 10 ⁵ poise. The thickness of each layer is 200 to 80 for the intermediate layer.
0 μm, the thickness of both outer layers in contact with the glass is 50 to 200
It is preferably set to μm.

As the method for obtaining the interlayer film of the present invention, any method may be used as long as an interlayer film satisfying the above conditions can be obtained, and examples thereof include a multilayer extrusion method, a laminating method and a casting method.

As a method of obtaining layers having different viscosities, for example, in the case of a plasticized polyvinyl butyral interlayer film, a method of changing the molecular weight of the polyvinyl butyral resin used as a raw material or changing the amount of the plasticizer is used. is there. Further, a method of changing the degree of shearing at the time of forming a sheet can be used.

[0015]

In the present invention, by increasing the viscosity of the base intermediate layer, a large strain of the glass having a thickness difference of 20 μm / 150 mm at the time of autoclave molding is generated along the shape of the base intermediate layer. It is fused and the glass distortion is corrected. In addition, a small strain that does not cause distortion is eliminated by the flow of the resin of both outer layers having low viscosity.

[0016]

EXAMPLES Next, examples of the present invention will be described. Interlayer film samples corresponding to Examples 1 to 4 and Comparative Examples 1 to 5 were prepared and their viscosities were measured, and laminated glass for evaluation was prepared using each of the interlayer film samples to observe distortion and peripheral peeling. I confirmed.

(Preparation of Intermediate Film) [Example 1] 100 parts by weight of a butyral resin having a degree of polymerization in terms of polyvinyl alcohol of 1700 and a degree of butyralization of 66 mol%, and triethylene glycol-di-2-
40 parts by weight of ethyl butyrate are melted and kneaded by an extruder and extruded into a sheet by a die, and the film thickness is 600 μm.
A plasticized polyvinyl butyral sheet of was obtained.

Further, 100 parts by weight of a butyral resin having a degree of polymerization in terms of polyvinyl alcohol of 1200 and a degree of butyralization of 66 mol%, 40 parts by weight of triethylene glycol-di-2-ethylbutyrate and 70 parts of methanol are used.
It dissolved in 0 parts by weight. This was applied onto both sides of the plasticized polyvinyl butyral sheet obtained as described above and dried to obtain a sheet having a three-layer structure in which the thickness of both layers was 100 μm.

Next, embossing with a roughness of 30 μm was provided on both sides of this sheet using embossing rolls. The total thickness of the obtained sheet was 790 μm. This was used as an interlayer film sample.

Example 2 An interlayer film sample was prepared under the same conditions as in Example 1 except that the polymerization degree of polyvinyl butyral of the interlayer was 2000.

[Example 3] An intermediate film sample was prepared under the same conditions as in Example 1 except that the polymerization degree of polyvinyl butyral of the intermediate layer was 1700 and the polymerization rates of both outer layers were 1400.

Example 4 An intermediate film sample was prepared under the same conditions as in Example 1 except that the polymerization degree of polyvinyl butyral of the intermediate layer was 1700 and the polymerization rates of both outer layers were 1000.

[Comparative Example 1] An intermediate film sample was prepared under the same conditions as in Example 1 except that the polymerization degree of polyvinyl butyral of the intermediate layer was 1700 and the polymerization rates of both outer layers were 1000.

Comparative Example 2 An interlayer film sample was prepared under the same conditions as in Example 1 except that the polymerization degree of polyvinyl butyral of the intermediate layer was 1400 and the polymerization degrees of both outer layers were 1200.

[Comparative Example 3] Using polyvinyl butyral having a degree of polymerization of 2000, a thickness of 7 was obtained in the same manner as in Example 1.
An embossed single-layer sheet having a thickness of 90 μm and a roughness of 30 μm was produced and used as an interlayer film sample.

Comparative Example 4 Using polyvinyl butyral having a polymerization degree of 1700, a single-layer plasticized polyvinyl butyral sheet was prepared in the same manner as in Comparative Example 1.

Comparative Example 5 Using polyvinyl butyral having a polymerization degree of 1400, a single-layer plasticized polyvinyl butyral sheet was produced in the same manner as in Comparative Example 1.

(Viscosity measurement) 1.5 g of the interlayer film samples of the above Examples and Comparative Examples were conditioned at 25 ° C. and 30 RH%, and then the diameter of the nozzle of the measuring die was measured using a flow tester CFT-500 manufactured by Shimadzu Corporation. 1 x 1 mm, load 20 kg / c
The viscosity was measured at m ² and a measurement temperature of 140 ° C.

(Production of laminated glass for evaluation) The thickness is 2.
Prepare two pieces of glass having a plate difference of 5 mm and a size of 30 × 30 cm, having a pair difference of 50 μm / 150 mm at the center and a pair difference of 100 μm at the edge of the glass. After sandwiching the interlayer film sample and passing it through a press roll at a glass surface temperature of 80 ° C. and a pressing pressure of 3 Kg / cm ² , a preliminary press was performed, and then an autoclave was used to perform main pressing at 13 Kg / cm ² , 140 ° C., and 20 minutes to combine. Glass was produced.

(Observation of Distortion) Each laminated glass is placed at a position of 3 m from the projector, has an angle of 15 ° with respect to the projected light flux, and is projected on a projection screen 1.8 m behind to visually observe the distortion of the projected image. I observed. The judgment was based on the inspection sample, and the larger the distortion, the larger the value.

(Confirmation of peripheral peeling) 5 in 60 ° C. hot water
The presence or absence of peeling was confirmed by repeating 30 cycles for each laminated glass, with one cycle consisting of immersion for 2 hours and drying with warm air at 80 ° C. for 2 hours.

The obtained laminated glass was subjected to a distortion observation and a peripheral peeling confirmation test. Table 1
The results are shown in. For Examples 1 to 4, good results were obtained as shown in Table 1.

[0033]

[Table 1]

[0034]

As is apparent from the above description, according to the interlayer film for laminated glass of the present invention, even when glass having a difference in pair is used, partial voids are generated, distortion is generated or the periphery thereof is generated. It is possible to manufacture a laminated glass in which peeling does not occur.

Claims (2)

[Claims] 1. An intermediate film for laminated glass, which has a three-layer structure in which an intermediate layer is sandwiched between both outer layers, and the viscosity of the intermediate layer at 140 ° C. is higher than the viscosity of both outer layers. 2. The viscosity of the intermediate layer at 140 ° C. is 6
× 10 ^{4 to} 6 × 10 ⁵ poises and 140 of both outer layers
The viscosity at ° C is 10 ⁴ to 10 ⁵ poise.
An interlayer film for laminated glass according to item 1.