INTERLAYER FOR LAMINATED GLASS, AND LAMINATED GLASS

Abstract

The present invention aims to provide an interlayer film for a laminated glass that generates heat under application of a voltage and warms frozen glass to melt frost or ice and also contributes to an excellent appearance of a laminated glass when used in the production of the laminated glass. The present invention can also provide a laminated glass produced using the interlayer film for a laminated glass. The present invention relates to an interlayer film for a laminated glass including: a conductive layer including a substrate containing a thermoplastic resin and a conductive film formed on the substrate; and a first resin layer containing a polyvinyl acetal stacked on the conductive film side of the conductive layer, the substrate having a thermal shrinkage measured in conformity with JIS C2151 of 1.0% to 3.5% in both of MD and TD directions after heat treatment at 150 C. for 30 minutes, the substrate and the first resin layer having a difference in the thermal shrinkage measured in conformity with JIS C2151 of 10% or less in absolute value in both of MD and TD directions after heat treatment at 150 C. for 30 minutes.

Claims

1. An interlayer film for a laminated glass comprising: a conductive layer comprising a substrate containing a thermoplastic resin and a conductive film formed on the substrate; and a first resin layer containing a polyvinyl acetal stacked on the conductive film side of the conductive layer, the substrate having a thermal shrinkage measured in conformity with JIS C2151 of 1.0% to 3.5% in both of MD and TD directions after heat treatment at 150 C. for 30 minutes, the substrate and the first resin layer having a difference in the thermal shrinkage measured in conformity with JIS C2151 of 10% or less in absolute value in both of MD and TD directions after heat treatment at 150 C. for 30 minutes.

2. The interlayer film for a laminated glass according to claim 1, wherein the interlayer film for a laminated glass further comprises a second resin layer containing a polyvinyl acetal stacked on the side opposite to the conductive film side of the conductive layer, and the substrate and the second resin layer have a difference in the thermal shrinkage measured in conformity with JIS C2151 of 10% or less in absolute value in both of MD and TD directions after heat treatment at 150 C. for 30 minutes.

3. A laminated glass comprising: a pair of glass plates; and the interlayer film for a laminated glass according to claim 1 interposed between the pair of glass plates.

4. A laminated glass comprising: a pair of glass plates; and the interlayer film for a laminated glass according to claim 2 interposed between the pair of glass plates.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0077] FIG. 1 is a schematic view illustrating an exemplary interlayer film for a laminated glass of the present invention.

DESCRIPTION OF EMBODIMENTS

[0078] Embodiments of the present invention are specifically described in the following with reference to, but not limited to, examples.

Example 1

(1) Preparation of a Conductive Layer

[0079] A polyethylene terephthalate (PET) film with a thickness of 50 m was used as a substrate. The thermal shrinkage of the substrate was measured in conformity with JIS C2151 after heat treatment at 150 C. for 30 minutes, and was 1.1% in the MD direction and 1.2% in the TD direction.

[0080] Sputtering was performed on the substrate with use of tin-doped indium oxide (ITO) as a target. The sputtering power was a 1,000 W direct current (DC), the atmospheric gas was argon, the gas flow rate was 50 sccm, and the sputtering pressure was 0.5 Pa. Under these conditions, a conductive film formed of tin-doped indium oxide (ITO) with a thickness of 0.05 m was formed. A conductive layer was thus obtained.

(2) Preparation of a First Resin Layer

[0081] To 100 parts by weight of polyvinyl butyral (hydroxy group content of 30 mol %, degree of acetylation of 1 mol %, degree of butyralization of 69 mol %, average degree of polymerization of 1,700) were added 40 parts by weight of triethylene glycol di-2-ethylhexanoate (3GO) as a plasticizer, 0.5 parts by weight of 2-(2-hydroxy-3-t-butyl-5-methylphenyl)-5-chlorobenzotriazole (Tinuvin 326 available from BASF SE) as a UV blocking agent, and 0.5 parts by weight of 2,6-di-t-butyl-p-cresol (BHT) as an antioxidant. They were sufficiently kneaded with a mixing roll to prepare a composition. The obtained composition was extruded from an extruder to provide a single-layered resin film with a thickness of 380 m. One surface of the obtained resin film was embossed to have a ten-point mean roughness Rz measured in conformity with JIS B0601-1982 of 35 m. The resin film was annealed at 50 C. for 30 minutes, thereby preparing a resin layer A as a first resin layer.

[0082] The thermal shrinkage of the obtained resin layer A was measured in conformity with JIS C2151 after heat treatment at 150 C. for 30 minutes, and was 5.3% in the MD direction and 5.8% in the TD direction.

(3) Production of an Interlayer Film for a Laminated Glass

[0083] Two sheets of the resin layers A were prepared. One resin layer A was stacked on the conductive layer in such a manner that the embossed surface faced the conductive layer side and the other resin layer A was stacked on the substrate side surface of the conductive layer in such a manner that the embossed surface faced the substrate side. The laminate was thermal compression bonded to produce an interlayer film for a laminated glass having a triple-layered structure (resin layer A/conductive layer/resin layer A). The thermal compression bonding was performed by a roll-to-roll method using a thermal compression bonding laminator (MRK-650Y type available from MCK Co., Ltd.) under the conditions of a heating temperature of 120 C., a bonding pressure of 2 kN, and a feed tension of 100 N. Laminating rolls used for the thermal compression bonding had upper and lower rolls both formed of rubber.

Examples 2 and 3 and Comparative Examples 1 to 4

[0084] An interlayer film for a laminated glass was produced in the same manner as in Example 1 except that the substrate of the conductive layer was changed as shown in Table 1.

Example 4

[0085] A resin layer B was obtained in the same manner as in the case of the resin layer A except that the conditions for annealing treatment of the resin film were changed to 50 C. for 45 minutes.

[0086] The thermal shrinkage of the obtained resin layer B was measured in conformity with JIS C2151 after heat treatment at 150 C. for 30 minutes, and was 4.3% in the MD direction and 4.8% in the TD direction.

[0087] An interlayer film for a laminated glass was produced in the same manner as in Example 1 except that the resin layer B was used instead of the resin layer A.

Comparative Example 5

[0088] A resin layer C was obtained in the same manner as in the case of the resin layer A except that the conditions for annealing treatment of the resin film were changed to 25 C. for 30 minutes.

[0089] The thermal shrinkage of the obtained resin layer C was measured in conformity with JIS C2151 after heat treatment at 150 C. for 30 minutes, and was 15.5% in the MD direction and 16.2% in the TD direction.

[0090] An interlayer film for a laminated glass was produced in the same manner as in Example 1 except that the resin layer C was used instead of the resin layer A.

Example 5

(1) Preparation of a Conductive Layer

[0091] A polyethylene terephthalate (PET) film with a thickness of 50 m was used as a substrate. The thermal shrinkage of the substrate was measured in conformity with JIS C2151 after heat treatment at 150 C. for 30 minutes, and was 1.1% in the MD direction and 1.2% in the TD direction.

[0092] Sputtering was performed on the substrate with use of silver as a target. The sputtering power was a 1,000 W direct current (DC), the atmospheric gas was argon, the gas flow rate was 50 sccm, and the sputtering pressure was 0.5 Pa. Under these conditions, a conductive film formed of silver with a thickness of 0.05 m was formed. A conductive layer was thus obtained.

(2) Preparation of a First Resin Layer

[0093] To 100 parts by weight of polyvinyl butyral (hydroxy group content of 30 mol %, degree of acetylation of 1 mol %, degree of butyralization of 69 mol %, average degree of polymerization of 1,700) were added 40 parts by weight of triethylene glycol di-2-ethylhexanoate (3GO) as a plasticizer, 0.5 parts by weight of 2-(2-hydroxy-3-t-butyl-5-methylphenyl)-5-chlorobenzotriazole (Tinuvin 326 available from BASF SE) as a UV blocking agent, and 0.5 parts by weight of 2,6-di-t-butyl-p-cresol (BHT) as an antioxidant. They were sufficiently kneaded with a mixing roll to prepare a composition. The obtained composition was extruded from an extruder to provide a single-layered resin film with a thickness of 380 m. One surface of the obtained resin film was embossed to have a ten-point mean roughness Rz measured in conformity with JIS B0601-1982 of 35 m. The resin film was annealed at 50 C. for 30 minutes, thereby preparing a resin layer D as a first resin layer.

[0094] The thermal shrinkage of the obtained resin layer D was measured in conformity with JIS C2151 after heat treatment at 150 C. for 30 minutes, and was 5.2% in the MD direction and 5.5% in the TD direction.

(3) Production of an Interlayer Film for a Laminated Glass

[0095] Two sheets of the resin layers D were prepared. One resin layer D was stacked on the conductive layer in such a manner that the embossed surface faced the conductive layer side and the other resin layer D was stacked on the substrate side surface of the conductive layer in such a manner that the embossed surface faced the substrate side. The laminate was thermal compression bonded to produce an interlayer film for a laminated glass having a triple-layered structure (resin layer D/conductive layer/resin layer D). The thermal compression bonding was performed by a roll-to-roll method using a thermal compression bonding laminator (MRK-650Y type available from MCK Co., Ltd.) under the conditions of a heating temperature of 120 C., a bonding pressure of 2 kN, and a feed tension of 100 N. Laminating rolls used for the thermal compression bonding had upper and lower rolls both formed of rubber.

Example 6

(1) Preparation of a Conductive Layer

[0096] A polyimide film with a thickness of 50 m was used as a substrate. The thermal shrinkage of the substrate was measured in conformity with JIS C2151 after heat treatment at 150 C. for 30 minutes, and was 1.1% in the MD direction and 1.2% in the TD direction.

[0097] Sputtering was performed on the substrate with use of silver as a target. The sputtering power was a 1,000 W direct current (DC), the atmospheric gas was argon, the gas flow rate was 50 sccm, and the sputtering pressure was 0.5 Pa. Under these conditions, a conductive film formed of silver with a thickness of 0.05 m was formed. A conductive layer was thus obtained.

(2) Preparation of a First Resin Layer

[0098] To 100 parts by weight of polyvinyl butyral (hydroxy group content of 30 mol %, degree of acetylation of 1 mol %, degree of butyralization of 69 mol %, average degree of polymerization of 1,700) were added 40 parts by weight of triethylene glycol di-2-ethylhexanoate (3GO) as a plasticizer, 0.5 parts by weight of 2-(2-hydroxy-3-t-butyl-5-methylphenyl)-5-chlorobenzotriazole (Tinuvin 326 available from BASF SE) as a UV blocking agent, and 0.5 parts by weight of 2,6-di-t-butyl-p-cresol (BHT) as an antioxidant. They were sufficiently kneaded with a mixing roll to prepare a composition. The obtained composition was extruded from an extruder to provide a single-layered resin film with a thickness of 380 m. One surface of the obtained resin film was embossed to have a ten-point mean roughness Rz measured in conformity with JIS B0601-1982 of 35 m. The resin film was annealed at 50 C. for 30 minutes, thereby obtaining a resin layer E as a first resin layer.

[0099] The thermal shrinkage of the obtained resin layer E was measured in conformity with JIS C2151 after heat treatment at 150 C. for 30 minutes, and was 5.4% in the MD direction and 5.5% in the TD direction.

(3) Production of an Interlayer Film for a Laminated Glass

[0100] Two sheets of the resin layers E were prepared. One resin layer E was stacked on the conductive layer in such a manner that the embossed surface faced the conductive layer side and the other resin layer E was stacked on the substrate side surface of the conductive layer in such a manner that the embossed surface faced the substrate side. The laminate was thermal compression bonded to produce an interlayer film for a laminated glass having a triple-layered structure (resin layer E/conductive layer/resin layer E). The thermal compression bonding was performed by a roll-to-roll method using a thermal compression bonding laminator (MRK-650Y type available from MCK Co., Ltd.) under the conditions of a heating temperature of 120 C., a bonding pressure of 2 kN, and a feed tension of 100 N. Laminating rolls used for the thermal compression bonding had upper and lower rolls both formed of rubber.

Evaluation

[0101] The interlayer films for a laminated glass obtained in the examples and comparative examples were evaluated by the following methods.

[0102] Table 1 shows the results.

(1) Appearance Evaluation of Laminated Glass

[0103] Windshields for vehicles were produced using the interlayer films for a laminated glass obtained in the examples and comparative examples. The windshields for vehicles have a curved portion in accordance with the shape of a vehicle.

[0104] An interlayer film for a laminated glass was sandwiched between two clear glass plates and parts sticking out from the laminate were cut off, thereby preparing a laminated glass structure. The obtained laminated glass structure was placed in a rubber bag and then connected to a vacuum suction device. The rubber bag was heated so that the temperature of the laminated glass structure (preliminary pressure bonding temperature) reached 70 C., while being held under a reduced pressure of 60 kPa (absolute pressure of 16 kPa) for 10 minutes. Thereafter, the pressure was returned to atmospheric pressure, whereby the preliminary pressure bonding was completed. The preliminarily pressure-bonded laminated glass structure was placed in an autoclave, and held at a temperature of 140 C. and a pressure of 1,300 kPa for 10 minutes. Thereafter, the temperature was lowered to 50 C. and the pressure was returned to atmospheric pressure, whereby the final pressure bonding was completed. Each windshield for vehicles was thus obtained.

[0105] Visual observation was performed on the obtained windshields for vehicles as a whole, particularly focusing on the curved part of the glass near the windshield periphery.

(Good): Appearance defects including creases or crinkles relative to the glass surface were not at all observed.
x (Poor): Appearance defects including creases or crinkles relative to the glass surface were observed.

(2) Change in the Resistance Value of Conductive Layer

[0106] For each of the interlayer films for a laminated glass obtained in the examples and comparative examples, the resistance value of the conductive layer in the state of the interlayer film for a laminated glass was measured. The resistance value was measured as follows. First, a copper foil tape having a width of 10 mm and a length of 100 mm was tightly attached to each end of the conductive layer of the interlayer film to serve as an electrode. Then, a 48-V voltage was applied thereto using a DC power source (PWR800L available from Kikusui Electronics Corp.) and the resistance value at that time was measured. For the measurement of the resistance value, a high-precision high-performance resistivity meter Loresta-GX (Mitsubishi Chemical Analytech Co., Ltd.) was used.

[0107] Separately, a laminated glass was produced by the same method as that employed for the appearance evaluation of the laminated glass. The produced laminated glass was connected to a power source via copper foil tapes in the same way as in the case of the interlayer film, and the resistance value of the conductive layer in the obtained laminated glass was measured.

[0108] The evaluation was performed using the absolute value A of the resistance value in the state of an interlayer film for a laminated glass and the absolute value B of the resistance value after production of a laminated glass, based on the following criteria.

(Excellent): Difference between A and B was less than 5 /sq.
(Good): Difference between A and B was 5 /sq or more but less than 10 /sq.
x (Poor): Difference between A and B was 10 /sq or more.

TABLE-US-00001 TABLE 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Conductive Conductive Material ITO ITO ITO ITO Ag Ag layer film Thickness (m) 0.05 0.05 0.05 0.05 0.05 0.05 Substrate Material PET PET PET PET PET Polyimide Thickness (m) 50 50 50 50 50 50 MD thermal shrinkage (%) 1.1 2.3 3.4 1.1 1.1 1.1 TD thermal shrinkage (%) 1.2 2.2 3.2 1.2 1.2 1.2 First resin Type A A A B D E layer MD thermal shrinkage (%) 5.3 5.3 5.3 4.3 5.2 5.4 TD thermal shrinkage (%) 5.8 5.8 5.8 4.8 5.5 5.5 Diffirence in thermal MD direction (%) 4.2 3.0 1.9 3.2 4.1 4.3 shrinkage between TD direction (%) 4.6 3.6 2.6 3.6 4.3 4.3 substrate and resin layer Evaluation Appearance evaluation Change in resistance value of conductive layer Comparative Comparative Comparative Comparative Comparative Example 1 Example 2 Example 3 Example 4 Example 5 Conductive Conductive Material ITO ITO ITO ITO ITO layer film Thickness (m) 0.05 0.05 0.05 0.05 0.05 Substrate Material PET PET PET PET PET Thickness (m) 50 50 50 50 50 MD thermal shrinkage (%) 5.0 0.6 5.0 2.3 1.1 TD thermal shrinkage (%) 5.0 0.7 3.2 0.7 1.2 First resin Type A A A A C layer MD thermal shrinkage (%) 5.3 5.3 5.3 5.3 15.5 TD thermal shrinkage (%) 5.8 5.8 5.8 5.8 16.2 Diffirence in thermal MD direction (%) 0.3 4.7 0.3 3.0 14.4 shrinkage between TD direction (%) 0.8 5.1 2.6 5.1 15.0 substrate and resin layer Evaluation Appearance evaluation X X X Change in resistance value of X X conductive layer

INDUSTRIAL APPLICABILITY

[0109] The present invention can provide an interlayer film for a laminated glass that generates heat under application of a voltage and warms frozen glass to melt frost or ice and also contributes to an excellent appearance of a laminated glass when used in the production of the laminated glass. The present invention can also provide a laminated glass produced using the interlayer film for a laminated glass.

REFERENCE SIGNS LIST

[0110] 1: Interlayer film for a laminated glass [0111] 2: Conductive layer [0112] 21: Substrate [0113] 22: Conductive film [0114] 3: First resin layer [0115] 4: Second resin layer