Intermediate film for laminated glass, and laminated glass

Abstract

The present invention aims to provide an interlayer film for a laminated glass which is easily peelable without autohesion even after storage in a stacked state, and a laminated glass prepared using the interlayer film for a laminated glass. The present invention relates to an interlayer film for a laminated glass, having a large number of protrusions on at least one surface, the surface having an arrangement density of the protrusions of 3 protrusions/mm.sup.2 or more, and the protrusions having an area ratio of 15 to 75% to the surface.

Claims

1. An interlayer film for a laminated glass, having a large number of protrusions on at least one surface, wherein the surface has an arrangement density of the protrusions of 3 protrusions/mm.sup.2 or more, wherein the protrusions have an area ratio of 15% to 75% to the surface, and wherein the protrusions each have an arithmetical mean height Sa on the surface of 200 nm or more as measured in conformity with ISO 25178.

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

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a view schematically illustrating an exemplary interlayer film for a laminated glass having a large number of spherical protrusions on a surface.

(2) FIG. 2 is a view schematically illustrating an exemplary interlayer film for a laminated glass having a large number of blockish protrusions on a surface.

(3) FIG. 3 is a view schematically illustrating the case where interlayer films for a laminated glass each having protrusions on a surface are stacked.

DESCRIPTION OF EMBODIMENTS

(4) Embodiments of the present invention are more specifically described in the following with reference to, but not limited to, examples.

Example 1

(5) (1) Preparation of an Interlayer Film for a Laminated Glass

(6) Polyvinyl alcohol having an average degree of polymerization of 1,700 was acetalized with n-butyraldehyde to give polyvinyl butyral (PVB, acetyl group content: 1 mol %, butyral group content: 69.1 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 kneaded well with a mixing roll to give a resin composition.

(7) The obtained resin composition was extruded using an extruder to provide a resin film having a thickness of 760 m. A fine emboss pattern was formed on surfaces of this resin film according to the embossing method with controlled melt fracture by setting the distance from the die to the surface of a cooling water tank to 100 mm (first step).

(8) A large number of spherical protrusions were formed on the surfaces of the obtained resin film by the following procedure.

(9) A pair of rolls including a metal roll having a surface processed with a mill and a rubber roll having a JIS hardness of 45 to 75 was used as a device for transferring a pattern of protrusions and recesses. The resin film after the first step was passed through the device for transferring a pattern of protrusions and recesses, thereby forming a large number of spherical protrusions on one of the surfaces. The transferring conditions employed here were a temperature of the interlayer film for a laminated glass of 70 C., a temperature of the rolls of 140 C., a linear velocity of 10 m/min, and a pressure adjusted so as to produce the desired roughness.

(10) Then, the same operations for formation of a large number of spherical protrusions were performed on the other surface of the resin film to obtain an interlayer film for a laminated glass.

(11) (2) Measurement of Surface State of the Interlayer Film for a Laminated Glass

(12) (2-1) Rz Value Measurement

(13) The ten-point average roughness (Rz) on both surfaces of the obtained interlayer film was measured by the method in conformity with JIS B-0601 (1994). The measuring instrument used was Surfcorder SE300 available from Kosaka Laboratory Ltd. The measurement was performed using a stylus profilometer at a cut-off value of 2.5 mm, a standard length of 2.5 mm, an evaluation length of 12.5 mm, and a measurement rate of 0.5 mm/s, with a stylus having a tip radius of 2 m and a tip angle of 60. The measurement environment was 23 C. and 30 RH %. The stylus was moved in a direction perpendicular to the groove direction of engraved lines.

(14) (2-2) Apex Sa Value Measurement

(15) The surface of the interlayer film for a laminated glass was measured using a three-dimensional white light interference microscope (ContourGT-K available from Bruker AXS GmbH) in a 1 mm square field of view at an objective lens magnification of 115 times, an internal lens magnification of 0.5 times, and a resolution set to Full resolution to obtain images. Analytical software Vision64 included in the apparatus was used in image processing. Conditions for the planarization and noise removal processes involved performing the first processing Terms Removal (F-Operator) on Analysis Toolbox under the analysis condition Tilt only (Plane Fit), performing the second processing Statistic Filter under the analysis conditions Filter type: Sigma and Filter size: 5, and further performing the processing data Restore by selecting the analysis condition Legacy, selecting Restore Edge condition, and setting Iteration condition to a value for sufficient data complement. In the third processing Mask data to extract image data on only the protrusions, the Height threshold of a histogram displayed under the analysis condition Histogram Mask was determined to be between 0.2 and 0.2 m, and data on height regions equal to or more than the threshold was extracted under the condition Mask: Left. The successful setting of the threshold to between 0.2 and 0.2 m was confirmed from the histogram display of the data after the extraction. In order to remove coarse protrusions and recesses, the fourth processing Gaussian Regression Filter was performed under the analysis conditions Short wavelength pass, order: 2, Type: Regular, and Long wavelength cutoff: 0.025 mm, and advance setup was performed under initial conditions. The image data after the first processing through the third processing was subjected to the fourth processing S parameters-height under the analysis condition Removal tilt: True. The resulting Sa was used as the arithmetical mean height Sa value.

(16) (2-3) Arrangement Density Measurement of Protrusions

(17) The surface of the interlayer film for a laminated glass was measured using a three-dimensional white light interference microscope (ContourGT-K available from Bruker AXS GmbH) in a 4 mm square field of view at an objective lens magnification of 50 times and an internal lens magnification of 0.5 times to obtain images. In this operation, light quantity and threshold were set as appropriate so as to minimize noise in the measurement. Then, analytical software Vision64 included in the apparatus was used in image processing. Conditions for the planarization and noise removal processes involved performing the first processing Terms Removal (F-Operator) on Analysis Toolbox under the analysis condition Tilt only (Plane Fit) and performing the second processing Statistic Filter under the analysis conditions Filter type: Sigma and Filter size: 5. The third processing Multi Region to extract the areas of only the protrusions was performed under analysis conditions involving Zero level: Background, Region Finding Routine: By Threshold, threshold: 1 m, and Region Finding option including minimum Region size: 5,000 m.sup.2 and Region Level: Peaks with Exclude Edge Region not selected. The number of the protrusions extracted by the third processing was counted to calculate the arrangement density of the protrusions per mm.sup.2. Protrusions that were not wholly displayed in an image were counted as .

(18) (2-4) Measurement of Area Ratio of Protrusions to Surface

(19) The measurement employed a three-dimensional white light interference microscope (ContourGT-K available from Bruker AXS GmbH). The surface of the interlayer film for a laminated glass was measured in a 4 mm square field of view at an objective lens magnification of 50 times and an internal lens magnification of 0.5 times to obtain images. In this operation, light quantity and threshold were set as appropriate so as to minimize noise in the measurement. Then, analytical software Vision64 included in the apparatus was used in image processing. Conditions for the planarization and noise removal processes involved performing the first processing Terms Removal (F-Operator) on Analysis Toolbox under the analysis condition Tilt only (Plane Fit) and performing the second processing Statistic Filter under the analysis conditions Filter type: Sigma and Filter size: 5. The third processing Multi Region to extract the areas of only the protrusions was performed under analysis conditions involving Zero level: Background, Region Finding Routine: By Threshold, threshold: 1 m, and Region Finding option including minimum Region size: 5,000 m.sup.2 and Region Level: Peaks with Exclude Edge Region not selected. The areas of the protrusions obtained by the third processing were totalized to calculate the area ratio of the protrusions per mm.sup.2.

Examples 2 to 6 and Comparative Examples 1 to 5

(20) An interlayer film for a laminated glass was produced by the method in conformity with Example 1, except that the pattern on the metal roll and the transferring conditions were changed to attain the surface state as shown in Table 1 or 2.

Examples 7 and 8

(21) An interlayer film for a laminated glass was produced by the method in conformity with Example 1, except that the distance from the die to the surface of a cooling water tank was set to 50 mm, and the pattern on the metal roll and the transferring conditions were changed to attain the surface state as shown in Table 1.

Comparative Example 6

(22) An interlayer film for a laminated glass was produced by the method in conformity with Example 1, except that the distance from the die to the surface of a cooling water tank was set to 300 mm, and the pattern on the metal roll and the transferring conditions were changed to attain the surface state as shown in Table 2.

Examples 9 to 16

(23) An interlayer film for a laminated glass was produced by the method in conformity with Example 1, except that the pattern on the metal roll and the transferring conditions were changed to attain the surface state as shown in Table 3.

Examples 17 and 18

(24) An interlayer film for a laminated glass was produced by the method in conformity with Example 1, except that the composition of the polyvinyl butyral used was changed as shown in Table 3, and the pattern on the metal roll and the transferring conditions were changed to attain the surface state as shown in Table 3.

Example 19

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

(26) Polyvinyl alcohol having an average degree of polymerization of 1,700 was acetalized with n-butyraldehyde to give polyvinyl butyral (PVB, acetyl group content: 1 mol %, butyral group content: 69 mol %, hydroxy group content: 30 mol %). To 100 parts by mass of the polyvinyl butyral were added 36 parts by mass of triethylene glycol-di-2-ethylhexanoate (3GO) as a plasticizer. The mixture was kneaded well with a mixing roll to give a resin composition for a protective layer.

(27) (Preparation of a Resin Composition for an Intermediate Layer)

(28) Polyvinyl alcohol having an average degree of polymerization of 3,000 was acetalized with n-butyraldehyde to give polyvinyl butyral (PVB, acetyl group content: 12.5 mol %, butyral group content: 64.2 mol %, hydroxy group content: 23.3 mol %). To 100 parts by mass of the polyvinyl butyral were added 76.5 parts by mass of triethylene glycol-di-2-ethylhexanoate (3GO) as a plasticizer, and the mixture was mixed well with a mixing roll to give a resin composition for an intermediate layer.

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

(30) The obtained resin composition for an intermediate layer and resin composition for a protective layer were co-extruded using a co-extruder to form an interlayer film for a laminated glass having a triple layer structure including a first protective layer made of the resin composition for a protective layer, an intermediate layer made of the resin composition for an intermediate layer, and a second protective layer made of the resin composition for a protective layer, stacked in the stated order. The extrusion conditions were set such that the first and second protective layers each had a thickness of 350 m and the intermediate layer had a thickness of 100 m in an interlayer film for a laminated glass to be obtained after formation of protrusions and recesses.

(31) Then, an interlayer film for a laminated glass was produced by the method in conformity with Example 1, except that the pattern on the metal roll and the transferring conditions were changed to attain the surface state as shown in Table 4.

Examples 20 to 24 and Comparative Examples 7 to 8

(32) An interlayer film for a laminated glass was produced by the method in, conformity with Example 1, except that the pattern on the metal roll and the transferring conditions were changed to attain the surface state as shown in Table 4 or 5.

(33) (Evaluation)

(34) In relation to the interlayer film for a laminated glass obtained in each of the examples and comparative examples, evaluation was conducted by the following methods. The results are shown in Tables 1 to 5.

(35) (1) Evaluation of Autohesion Force

(36) The interlayer film for a laminated glass obtained in each of the examples and comparative examples was cut into a size of 150 mm in length and 150 mm in width to obtain a test specimen. Two test specimens thus obtained were stacked, and a glass plate (weight: 5.8 kg) was placed thereon with a release paper as a means of releasing treatment interposed therebetween. The release paper was prepared by silicone coating of a base paper. In this state, the test specimens were left for 168 hours in a constant temperature and humidity bath adjusted to a temperature of 23 C. and a humidity of 30%.

(37) Then, 2 cm end portions of the two test specimens were peeled from each other, and the end portions of the two test specimens were fixed with 15 cm wide grippers, respectively. The 180 peel strength between the two test specimens was measured in conformity with JIS K-6854-3 (1999) at a peel rate of 50 cm/min in an environment of a temperature of 23 C. and a humidity of 30%, and the average peel strength (N/cm) of a peeling distance from 50 mm to 200 mm was calculated. The other conditions conformed to JIS K-6854-3 (1999). The obtained value was used as the autohesion force of the interlayer film for a laminated glass.

(38) For peeling by a machine transporting interlayer films for a laminated glass or by human power, the autohesion force is preferably 0.5 N/cm or less, more preferably 0.4 N/cm or less, particularly preferably 0.3 N/cm or less.

(39) (2) Evaluation of Deaeration Properties

(40) The interlayer film for a laminated glass obtained in each of the examples and comparative examples was stored for three hours in an environment of 23 C. and 30% humidity and then sandwiched between two clear glass plates (30 cm in length30 cm in width2.5 mm in thickness), and the portions of the film protruding from the glass plates were cut off. The laminated glass structure (laminate) thus obtained was transferred into a rubber bag, which was then connected to a vacuum suction device. The rubber bag was heated so that the temperature of the laminated glass structure (laminate) (preliminary pressure bonding temperature) reached 70 C., while being held under a reduced pressure of 30 kPa (absolute pressure: 16 kPa) for 10 minutes. Thereafter, the pressure was returned to atmospheric pressure, whereby the preliminary pressure bonding was completed. The surface temperature of the glass plates at the start of the preliminary pressure bonding (deaeration onset temperature) was set to 60 C.

(41) The preliminarily pressure bonded laminated glass structure (laminate) was placed in an autoclave, and held at a temperature of 140 C. and a pressure of 1,300 kPa for 10 minutes. The temperature was lowered to 50 C. and the pressure was returned to atmospheric pressure, whereby the final pressure bonding was completed. A laminated glass was thus prepared.

(42) The obtained laminated glass was heated in an oven of 140 C. for two hours. The appearance of the laminated glass was visually observed after the laminated glass was taken out of the oven and allowed to cool for three hours. Twenty laminated glasses were tested for each example. The number of laminated glass samples having foaming (bubbles) was examined, and the deaeration properties were evaluated according to the following criteria.

(43) (Good): Five or less samples had foaming.

(44) x (Poor): More than 5 samples had foaming.

(45) TABLE-US-00001 TABLE 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Compo- PVB Average degree 1700 1700 1700 1700 1700 1700 1700 1700 sition of polymerization of inter- Degree of 69 69 69 69 69 69 69 69 layer butyralization (mol %) film Degree of 1 1 1 1 1 1 1 1 acetylation (mol %) Hydroxy group 30 30 30 30 30 30 30 30 content (mol %) Amount (parts 100 100 100 100 100 100 100 100 by mass) Plasticizer Type 3GO 3GO 3GO 3GO 3GO 3GO 3GO 3GO Amount (parts 40 40 40 40 40 40 40 40 by mass) Surface First Ten-point average 50 43 35 30 40 42 55 48 pattern surface roughness Rz (m) of inter- Apex Sa (nm) 279 279 279 279 279 279 500 500 layer Arrangement 4.6 28.9 4.6 12.8 4.6 28.9 4.6 28.9 film density of protrusions (protrusions/mm.sup.2) Area ratio of 61.0 61.0 44.4 44.4 16.0 16.0 44.4 44.4 protrusions (%) Second Ten-point average 48 40 42 29 38 41 53 45 surface roughness Rz (m) Apex Sa (nm) 244.5 244.5 244.5 244.5 244.5 244.5 488 488 Arrangement density 4.5 28.9 4.5 12.9 4.5 28.9 4.5 28.9 of protrusions (protrusions/mm.sup.2) Area ratio of 61.0 61.0 44.4 44.4 16.0 16.0 44.4 44.4 protrusions (%) Eval- Autohesion force (N/cm) 0.49 0.49 0.49 0.39 0.49 0.30 0.30 0.25 uation Deaeration properties

(46) TABLE-US-00002 TABLE 2 Comparative Comparative Comparative Comparative Comparative Comparative Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Compo- PVB Average degree 1700 1700 1700 1700 1700 1700 sition of polymerization of inter- Degree of 69 69 69 69 69 69 layer butyralization (mol %) film Degree of 1 1 1 1 1 1 acetylation (mol %) Hydroxy group 30 30 30 30 30 30 content (mol %) Amount (parts 100 100 100 100 100 100 by mass) Plasticizer Type 3GO 3GO 3GO 3GO 3GO 3GO Amount (parts 40 40 40 40 40 40 by mass) Surface First Ten-point average 45 40 35 30 50 38 pattern surface roughness Rz (m) of inter- Apex Sa (nm) 279 279 279 279 279 154 layer Arrangement 4.6 9.4 28.9 2.2 2.2 4.6 film density of protrusions (protrusions/mm.sup.2) Area ratio of 76.8 76.8 76.8 61.0 44.4 11.1 protrusions (%) Second Ten-point average 44 42 33 32 48 39 surface roughness Rz (m) Apex Sa (nm) 244.5 244.5 244.5 244.5 244.5 135 Arrangement density 4.5 12.9 28.9 2.2 2.2 4.5 of protrusions (protrusions/mm.sup.2) Area ratio of 76.8 76.8 76.8 61.0 44.4 11.1 protrusions (%) Eval- Autohesion force (N/cm) 0.72 0.71 0.73 0.78 0.75 1.95 uation Deaeration properties x x x

(47) TABLE-US-00003 TABLE 3 Example Example Example Example Example Example 9 10 11 12 13 14 Compo- PVB Average 1700 1700 1700 1700 1700 1700 sition degree of of poly- inter- merization layer Degree of 69 69 69 69 69 69 film buty- ralization (mol %) Degree of 1 1 1 1 1 1 acetylation (mol %) Hydroxy 30 30 30 30 30 30 group content (mol %) Amount 100 100 100 100 100 100 (parts by mass) Plasti- Type 3GO 3GO 3GO 3GO 3GO 3GO cizer Amount 40 40 40 40 40 40 (parts by mass) Surface First Ten-point 36 38 38 33 30 33 pattern surface average of roughness inter- Rz (m) layer Apex Sa 270 260 250 270 255 279 film (nm) Arrange- 35.3 51.8 79.0 35.0 52.0 4.5 ment density of protrusions (protrusions/ mm.sup.2) Area 60.0 59.0 58.0 42.0 41.0 27.0 ratio of protrusions (%) Second Ten-point 38 34 37 29 28 33 surface average roughness Rz (m) Apex Sa 224 255 220 225 230 240 (nm) Arrange- 35.0 51.5 77.5 37.0 51.8 4.5 ment density of protrusions (protrusions/ mm.sup.2) Area 59.0 58.0 57.2 44.0 42.5 26.2 ratio of protrusions (%) Eval- Autohesion force 0.46 0.44 0.36 0.29 0.24 0.40 uation (N/cm) Deaeration properties Example Example Example Example 15 16 17 18 Compo- PVB Average 1700 1700 1700 1700 sition degree of of poly- inter- merization layer Degree of 69 69 69.9 68.5 film buty- ralization (mol %) Degree of 1 1 1.1 0.5 acetylation (mol %) Hydroxy 30 30 29 31 group content (mol %) Amount 100 100 100 100 (parts by mass) Plasti- Type 3GO 3GO 3GO 3GO cizer Amount 40 40 40 40 (parts by mass) Surface First Ten-point 34 40 45 42 pattern surface average of roughness inter- Rz (m) layer Apex Sa 255 279 250 245 film (nm) Arrange- 35.3 35.0 4.5 4.5 ment density of protrusions (protrusions/ mm.sup.2) Area 26.5 15.3 60.0 60.5 ratio of protrusions (%) Second Ten-point 40 36 42 43 surface average roughness Rz (m) Apex Sa 230 240 255 260 (nm) Arrange- 35.0 35.3 4.5 4.5 ment density of protrusions (protrusions/ mm.sup.2) Area 27.5 15.5 60.0 61.0 ratio of protrusions (%) Evaluation Autohesion force 0.21 0.27 0.53 0.49 (N/cm) Deaeration properties

(48) TABLE-US-00004 TABLE 4 Example 19 Example 20 Example 21 Example 22 First PVB Average degree 1700 1700 1700 1700 and of polymerization second Degree of 69 69 69 69 pro- butyralization (mol %) tective Degree of 1 1 1 1 layers acetylation (mol %) Hydroxy group 30 30 30 30 content (mol %) Amount (parts 100 100 100 100 by mass) Plasticizer Type 3GO 3GO 3GO 3GO Amount (parts 36 36 36 36 by mass) Structure Thickness (m) 350 350 350 350 Inter- PVB Average degree 3000 3000 2300 1700 mediate of polymerization layer Degree of 64.2 64.2 64.2 64.2 butyralization (mol %) Degree of 12.5 12.5 12.5 12.5 acetylation (mol %) Hydroxy group 23.3 23.3 23.3 23.3 content (mol %) Amount (parts 100 100 100 100 by mass) Plasticizer Type 3GO 3GO 3GO 3GO Amount (parts 76.5 76.5 76.5 76.5 by mass) Structure Thickness (m) 100 100 100 100 Whole Structure Structure First protective First protective First protective First protective inter- layer/intermediate layer/intermediate layer/intermediate layer/intermediate layer layer/second layer/second layer/second layer/second film protective layer protective layer protective layer protective layer Thickness (m) 800 800 800 800 Surface First Ten-point average 35 30 32 33 pattern surface roughness Rz (m) of inter- Apex Sa (nm) 253 253 250 268 layer Arrangement 4.6 12.8 12.8 12.8 film density of protrusions (protrusions/mm.sup.2) Area ratio of 44.4 45.0 44.0 42.0 protrusions (%) Second Ten-point average 42 29 32 32 surface roughness Rz (m) Apex Sa (nm) 224 220 235 239 Arrangement density 4.5 12.9 12.9 12.9 of protrusions (protrusions/mm.sup.2) Area ratio of 44.4 44.0 43.9 44.2 protrusions (%) Eval- Autohesion force (N/cm) 0.53 0.42 0.43 0.43 uation Deaeration properties

(49) TABLE-US-00005 TABLE 5 Comparative Comparative Example 23 Example 24 Example 7 Example 8 First PVB Average degree 1700 1700 1700 1700 and of polymerization second Degree of 69.9 68.5 69 69 pro- butyralization (mol %) tective Degree of 1.1 0.5 1 1 layers acetylation (mol %) Hydroxy group 29 31 30 30 content (mol %) Amount (parts 100 100 100 100 by mass) Plasticizer Type 3GO 3GO 3GO 3GO Amount (parts 39 36 36 36 by mass) Structure Thickness (m) 350 350 350 350 Inter- PVB Average degree 2300 2300 3000 3000 mediate of polymerization layer Degree of 77.8 67 64.2 64.2 butyralization (mol %) Degree of 1.5 8 12.5 12.5 acetylation (mol %) Hydroxy group 20.7 25 23.3 23.3 content (mol %) Amount (parts 100 100 100 100 by mass) Plasticizer Type 3GO 3GO 3GO 3GO Amount (parts 79 75 76.5 76.5 by mass) Structure Thickness (m) 100 100 100 100 Whole Structure Structure First protective First protective First protective First protective inter- layer/intermediate layer/intermediate layer/intermediate layer/intermediate layer layer/second layer/second layer/second layer/second film protective layer protective layer protective layer protective layer Thickness (m) 800 800 800 800 Surface First Ten-point average 35 30 44 32 pattern surface roughness Rz (m) of inter- Apex Sa (nm) 279 280 253 253 layer Arrangement 4.6 12.9 4.5 2.2 film density of protrusions (protrusions/mm.sup.2) Area ratio of 44.4 44.4 76.8 61.1 protrusions (%) Second Ten-point average 42 29 44 32 surface roughness Rz (m) Apex Sa (nm) 235 245 258 235 Arrangement density 4.5 12.9 4.5 2.2 of protrusions (protrusions/mm.sup.2) Area ratio of 44.4 44.4 76.8 61.3 protrusions (%) Eval- Autohesion force (N/cm) 0.55 0.44 0.71 0.79 uation Deaeration properties x

INDUSTRIAL APPLICABILITY

(50) The present invention can provide an interlayer film for a laminated glass which is easily peelable without autohesion even after storage in a stacked state, and a laminated glass prepared using the interlayer film for a laminated glass.