INTERMEDIATE FILM FOR LAMINATED GLASS, METHOD FOR PRODUCING INTERMEDIATE FILM FOR LAMINATED GLASS, AND LAMINATED GLASS

Abstract

The present invention aims to provide an interlayer film for a laminated glass which enables production of a laminated glass with suppressed occurrence of optical distortion, a method for producing the interlayer film for a laminated glass, and a laminated glass produced using the interlayer film for a laminated glass. The present invention relates to an interlayer film for a laminated glass produced by an extrusion lip embossing method utilizing melt fracture, the interlayer film for a laminated glass including a laminate that includes two or more resin layers in a stack and having a large number of protrusions and recesses on at least one surface, a maximum height Ry (m) and an average interval Sm (m) of the protrusions and recesses measured in conformity with JIS B 0601 (1994) on the surface with protrusions and recesses satisfying a formula (1):

(RySm)/23,500(1).

Claims

1. An interlayer film for a laminated glass produced by an extrusion lip embossing method utilizing melt fracture, the interlayer film for a laminated glass comprising a laminate that includes two or more resin layers in a stack and having a large number of protrusions and recesses on at least one surface, a maximum height Ry (m) and an average interval Sm (m) of the protrusions and recesses measured in conformity with JIS B 0601 (1994) on the surface with protrusions and recesses satisfying a formula (1):
(RySm)/23,500(1).

2. The interlayer film for a laminated glass according to claim 1, wherein the maximum height Ry (m) and the average interval Sm (m) of the protrusions and recesses measured in conformity with JIS B 0601 (1994) on the surface with protrusions and recesses satisfy a formula (2):
(RySm)/22,700(2).

3. The interlayer film for a laminated glass according to claim 1, wherein the interlayer film for a laminated glass after immersion in warm water at 50 C. for 10 minutes has a degree of shrinkage in a machine direction of 4% or less.

4. The interlayer film for a laminated glass according to claim 1, further having a large number of recesses each having a groove shape with a continuous bottom at least on one surface.

5. 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.

6. A method for producing the interlayer film for a laminated glass according to claim 1, comprising a step of providing a large number of protrusions and recesses on at least one surface of an interlayer film for a laminated glass by an extrusion lip embossing method utilizing melt fracture, the step including coextrusion of resins from a co-extruder under the following conditions: a resin pressure at an inlet of a die of 40 to 150 kgf/cm.sup.2, a resin temperature of 160 C. to 250 C., a die temperature of 100 C. to 270 C., a width of an outlet of the die of 700 to 3,500 mm, an extrusion amount per width of the outlet of the die of 130 to 1,700 kg/hr.Math.m, a film surface temperature immediately after ejection from the outlet of the die of 170 C. to 250 C., a distance from the outlet of the die to a cooling water tank of 10 to 400 mm, and a water temperature in the cooling water tank of 10 C. to 70 C.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0116] FIG. 1 shows a schematic view explaining the meaning of (RySm)/2 in the formula (1).

[0117] FIG. 2 shows a schematic view of an exemplary interlayer film for a laminated glass having, on a surface, recesses each having a groove shape with a continuous bottom and being adjacent and parallel to each other at equal intervals.

[0118] FIG. 3 shows a schematic view of an exemplary interlayer film for a laminated glass having, on a surface, recesses each having a groove shape with a continuous bottom and being adjacent and parallel to each other at equal intervals.

[0119] FIG. 4 shows a schematic view of an exemplary interlayer film for a laminated glass having, on a surface, recesses each having a groove shape with a continuous bottom and being adjacent and parallel to each other at unequal intervals.

[0120] FIG. 5 shows a schematic view of an exemplary interlayer film for a laminated glass, having a blockish pattern on a surface.

[0121] FIG. 6 shows a schematic view of an exemplary interlayer film for a laminated glass, having a spherical pattern on a surface.

DESCRIPTION OF EMBODIMENTS

[0122] Embodiments of the present invention are more specifically described in the following with reference to, but not limited to, examples.

Example 1

(1) Preparation of a Resin Composition for a Protective Layer

[0123] Polyvinyl alcohol having an average degree of polymerization of 1,700 was acetalized with n-butyraldehyde to give polyvinyl butyral (acetyl group content: 1 mol %, butyral group content: 69 mol %, hydroxy group content: 30 mol %). To 100 parts by mass of the polyvinyl butyral was added 40 parts by mass of triethylene glycol-di-2-ethylhexanoate (3GO) as a plasticizer, and the mixture was kneaded well with a mixing roll to give a resin composition for a protective layer.

(2) Preparation of a Resin Composition for a Sound Insulation Layer

[0124] Polyvinyl alcohol having an average degree of polymerization of 2,300 was acetalized with n-butyraldehyde to give polyvinyl butyral (acetyl group content: 12.5 mol %, butyral group content: 64.5 mol %, hydroxy group content: 23.0 mol %). To 100 parts by mass of the polyvinyl butyral was added 60 parts by mass of triethylene glycol-di-2-ethylhexanoate (3GO) as a plasticizer, and the mixture was kneaded well with a mixing roll to give a resin composition for a sound insulation layer.

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

[0125] The obtained resin composition for a protective layer and resin composition for a sound insulation layer were co-extruded from a co-extruder to form a laminate having a triple layer structure including a first surface layer (protective layer) made of the resin composition for a protective layer with a thickness of 350 m, an intermediate layer (sound insulation layer) made of the resin composition for a sound insulation layer with a thickness of 100 m, and a second surface layer (protective layer) made of the resin composition for a protective layer with a thickness of 350 m stacked in the stated order. The co-extrusion conditions were set as follows to provide protrusions and recesses, concurrently with the formation of an interlayer film for a laminated glass, by an extrusion lip embossing method utilizing melt fracture.

[0126] Specifically, protrusions and recesses were formed on both surfaces of an interlayer film for a laminated glass, concurrently with the formation of the interlayer film for a laminated glass, by the extrusion lip embossing method utilizing melt fracture under the following conditions: a resin pressure at an inlet of a die of 70 kgf/cm.sup.2, a resin composition temperature at the inlet of the die of 200 C., a die temperature of 210 C., a width at an outlet of the die of 1,000 mm, an extrusion amount per width of the outlet of the die of 300 kg/hr.Math.m, a film surface temperature immediately after ejection from the die of 200 C., a distance from the outlet of the die to a cooling water tank of 170 mm, and a water temperature in the cooling water tank of 10 C. to 20 C.

[0127] The obtained interlayer film for a laminated glass had a thickness of 800 m.

(4) Measurement of Protrusions and Recesses on a Surface

(4-1) Ry Value Measurement

[0128] The maximum height (Ry) on each surface of the obtained interlayer film for a laminated glass was measured by the method in conformity with JIS B-0601 (1994). The measurement was performed using Surfcorder SE300 available from Kosaka Laboratory Ltd. as a measuring instrument under the following conditions of a stylus profilometer: a cut-off value of 2.5 mm, a standard length of 2.5 mm, an evaluation length of 12.5 mm, a tip radius of a stylus of 2 m, a tip angle of the stylus of 60, and a measurement rate of 0.5 mm/s. The measurement environment was set to 23 C. and 30 RH %, and the stylus was moved in a direction parallel to the machine direction of the sheet. The measurement was performed five times while the measurement point was shifted by 3 mm in the width direction for each measurement. The average of the obtained values was employed as the value of Ry. The obtained Ry values were the same on both surfaces.

(4-2) Sm Value Measurement

[0129] The average interval (Sm) of the protrusions and recesses on each surface of the obtained interlayer film for a laminated glass was measured by the method in conformity with JIS B 0601 (1994). The measurement was performed using Surfcorder SE300 available from Kosaka Laboratory Ltd. as a measuring instrument under the following conditions of a stylus profilometer: a cut-off value of 2.5 mm, a standard length of 2.5 mm, an evaluation length of 12.5 mm, a tip radius of a stylus of 2 m, a tip angle of the stylus of 60, and a measurement rate of 0.5 mm/s. The measurement environment was set to 23 C. and 30 RH %, and the stylus was moved in a direction parallel to the machine direction of the sheet. The measurement was performed five times while the measurement point was shifted by 3 mm in the width direction for each measurement. The average of the obtained values was employed as the Sm value.

[0130] The obtained Sm values were the same on both surfaces.

(5) Measurement of a Degree of Shrinkage

[0131] The interlayer film for a laminated glass was cut into a rectangle (15 cm10 cm) to be used as a measurement sample. The cutting was performed in such a manner that a side in the machine direction became a longer side of the rectangle. The measurement sample was immersed in warm water at 50 C. for 10 minutes, and water on the surface was wiped off. The resulting measurement sample was cooled to 23 C. The length in the machine direction of the measurement sample was measured, and the degree of shrinkage in the machine direction was calculated by the following equation.

Degree of shrinkage (%)={1(length in machine direction after immersion)/(length in machine direction before immersion)}100

Examples 2 to 8, Comparative Examples 1 to 4

[0132] An interlayer film for a laminated glass was produced, and the protrusions and recesses on the surface and the degree of shrinkage were measured in the same manner as in Example 1, except that the conditions for providing protrusions and recesses by the extrusion lip embossing method utilizing melt fracture were changed. Specifically, the conditions including the resin pressure at the inlet of the die, the resin composition temperature at the inlet of the die, the die temperature, the extrusion amount per width of the outlet of the die, the film surface temperature immediately after ejection from the outlet of the die, the distance from the outlet of the die to the cooling water tank, and the water temperature in the cooling water tank were adjusted.

(Evaluation)

[0133] The interlayer film for a laminated glass obtained in each of the examples and comparative examples was cut to a size of 15 cm in the lengthwise direction (machine direction) and 30 cm in crosswise direction. Next, a step of preliminary pressure bonding was carried out by sandwiching the cut interlayer film for a laminated glass between two transparent float glass plates (15 cm in length30 cm in width, thickness of 2.5 mm) and then performing preliminary pressurization at 240 C. for three minutes. The obtained laminate was then pressure-bonded in an autoclave at 135 C. and 1.2 MPa for 20 minutes to be finally pressure-bonded. A laminated glass was thus obtained.

[0134] The obtained laminated glass was irradiated with light passing through a slit from a light source (halogen lamp), and distortion of the projected image on a screen was captured by a sensor (camera). The captured distortion was subjected to data processing using a computer, thereby obtaining an optical distortion value. A larger optical distortion value indicates greater optical distortion (distortion of image).

[0135] The method for measuring the optical distortion value was specifically described in the following. The optical distortion value was measured using a device disclosed in JP H07-306152 A, i.e., an optical distortion inspecting device having: a light source unit irradiating a light-transmitting object to be inspected with illumination light; a slit; a projection plane where the illumination light passing through the object to be inspected is projected; an image inputting part for generating a grayscale image by capturing the projection plane; and an image processing part for determining the presence or absence of distortion based on the variation in the gray level of the grayscale image generated by the image inputting part. Specifically, the optical distortion was evaluated by using EYE DICHO-COOL HALOGEN (15 V 100 W) produced by Iwasaki Electric Co., Ltd. as a light source, while the illuminance of the light source, the angle of the screen where optical distortion image is projected, and the angle of the camera were adjusted in such a manner that a laminated glass including a single layer film having a visible light transmittance in conformity with JIS R 3211 (1988) (value for Y under standard illuminant A, A-Y (380 to 780 nm)) of 88% (U4100 produced by Hitachi High-Technologies Corporation was used) had an optical distortion value of 1.14 and that the optical distortion value in a state of including no glass was adjusted to 1.30. The optical distortion was evaluated under the conditions of a laminated glass temperature of 25 C. As the optical distortion value, the values in the lengthwise direction and crosswise direction can be obtained. Here, the smaller value was used as the optical distortion value. The thermometer used was a contact-type thermometer. Tables 1 and 2 show the measurement results.

[0136] With the optical distortion value of 1.24 or less, when the laminated glass is used as a windshield for vehicles, flickering of signals or pedestrian crossings does not occur.

TABLE-US-00001 TABLE 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Production Resin pressure at inlet of die (kgf/cm.sup.2) 70 70 80 80 40 40 100 50 condition Resin temperature ( C.) 200 200 200 200 210 210 210 210 Die temperature ( C.) 210 200 190 190 200 200 200 210 Width of outlet of die (mm) 1000 1000 1000 1000 2000 2000 2000 2000 Extrusion amount per width (kg/hr.m) 300 300 300 300 250 250 250 250 Film surface temperature immediately 200 195 190 190 200 200 200 210 after ejection ( C.) Distance to cooling water tank (mm) 170 200 100 200 100 200 100 100 Water temperature in cooling water tank 10-20 15 15 15 15 15 20 15 ( C.) Protrusions Maximum height Ry (m) 14 17 22 23 12 10 21 30 and Average interval Sm of protrusions and 215 408 205 284 198 500 206 100 recesses recesses (m) on surface (Ry Sm)/2 1505 3468 2255 3266 1188 2500 2163 1500 Degree of shrinkage in warm water at 50 C. (%) 1.0 2.0 1.0 1.5 1.0 2.0 1.0 1.0 Optical distortion value 1.18 1.20 1.19 1.22 1.18 1.20 1.19 1.19

TABLE-US-00002 TABLE 2 Comparative Comparative Comparative Comparative Example 1 Example 2 Example 3 Example 4 Production Resin pressure at inlet of die (kgf/cm.sup.2) 300 300 90 90 condition Resin temperature ( C.) 200 180 200 190 Die temperature ( C.) 200 200 190 190 Width of outlet of die (mm) 2000 2000 80 100 Extrusion amount per width (kg/hr .Math. m) 250 250 300 300 Film surface temperature immediately after 195 190 190 190 ejection ( C.) Distance to cooling water tank (mm) 200 100 250 250 Water temperature in cooling water tank ( C.) 15 15 15 15 Protrusions Maximum height Ry (m) 24 32 26 29 and recesses Average interval Sm of protrusions and 465 426 302 326 on surface recesses (m) (Ry Sm)/2 5580 6616 3926 4727 Degree of shrinkage in warm water at 50 C. (%) 5.0 6.5 2.1 2.2 Optical distortion value 1.30 1.40 1.26 1.28

INDUSTRIAL APPLICABILITY

[0137] The present invention can provide an interlayer film for a laminated glass which enables production of a laminated glass with suppressed occurrence of optical distortion, a method for producing the interlayer film for a laminated glass, and a laminated glass produced using the interlayer film for a laminated glass.

REFERENCE SIGNS LIST

[0138] 1: Protrusions and recesses on a surface of an interlayer film for a laminated glass [0139] 11: Protrusion [0140] 12: Recess [0141] 21: Arbitrarily selected one recess [0142] 22: Recess adjacent to the arbitrarily selected one recess [0143] 23: Recess adjacent to the arbitrarily selected one recess [0144] A: Interval between recess 21 and recess 22 [0145] B: Interval between recess 21 and recess 23