Method for making laminated glass interlayer film and laminated glass and method for making the laminated glass

Abstract

A method in accordance with the present invention has: providing an ethylene-vinyl acetate copolymer; mixing the ethylene-vinyl acetate copolymer, a photoinitiator, a coupling agent, a crosslink-assisting agent, an ultraviolet light absorber, and a radical scavenger to obtain a mixture; and forming the mixture into a film at a specific temperature to obtain the laminated glass interlayer film. The laminated glass in accordance with the present invention is has high transmittance and low haze, and also shortens the production time, thereby enhancing the quality and applicability.

Claims

1. A method for making a laminated glass interlayer film, comprising the steps of: a) providing an ethylene-vinyl acetate copolymer; b) mixing an ethylene-vinyl acetate copolymer, an initiator, a coupling agent, a crosslink-assisting agent, an ultraviolet light absorber, and a radical scavenger to obtain a mixture, wherein the mixture consists of the ethylene-vinyl acetate copolymer, the initiator, the coupling agent, the crosslink-assisting agent, the ultraviolet light absorber, and the radical scavenger, and the initiator consists of a photoinitiator; and c) forming the mixture at a specific temperature to obtain the laminated glass interlayer film consisting of the mixture; wherein the ethylene-vinyl acetate copolymer contains 5 wt % to 70 wt % vinyl acetate groups; the ethylene-vinyl acetate copolymer has a melt flow rate ranging from 5 g/10 min to 50 g/10 min; the amount of the photoinitiator ranges from 0.1 wt % to 10 wt % based on the total amount of the mixture; the amount of the crosslink-assisting agent ranges from 0.1 wt % to 4 wt %; the amount of the coupling agent ranges from 0.01 wt % to 10 wt %; the coupling agent comprises tetra-n-propyl zirconate, tetra-n-butyl zirconate, titanate coupling agent LICA 12, titanate coupling agent LICA 38, butyl titanate phosphate, and titanium diisopropoxide bis(acetylacetonate), 3-(methacryloxypropyl) trimethoxysilane, 3-(methacryloyloxy) propyltriethoxysilane, (3-glycidoxypropyl) trimethoxysilane), (3-glycidoxypropyl) triethoxysilane, 3,4-epoxycyclohexylthyltrimethoxysilane, 3-aminopropyltriethoxysilane, or trimethoxysilyl ethene; the photoinitiator comprises a benzoin-based compound, a benzophenone-based compound or a rhodium-based compound; the ultraviolet light absorber comprises a benzophenone-based compound, a triazine-based compound or an amide-based compound; the crosslink-assisting agent comprises a polyfunctional compound containing an acrylic group or a vinyl group; the radical scavenger comprises a hindered phenol antioxidant or a hindered amine light stabilizer.

2. The method as claimed in claim 1, wherein the photoinitiator is a benzophenone-based compound.

3. A method for making a laminated glass, comprising the steps of: a) sandwiching a laminated glass interlayer film prepared as described in claim 1 between two glass sheets to obtain a laminated structure; b) vacuum laminating the laminated structure at a lamination temperature; c) applying an ultraviolet or visible light of 4 J to 12 J to the laminated structure at a photo-curing temperature to produce the laminated glass.

4. The method as claimed in claim 3, wherein the lamination temperature ranges from greater than or equal to 90 C. to less than or equal to 150 C.

5. The method as claimed in claim 3, wherein the lamination temperature ranges from greater than or equal to 75 C. to less than 90 C.

6. The method as claimed in claim 3, wherein the photo-curing temperature ranges from greater than or equal to 100 C. to less than or equal to 140 C.

7. The method as claimed in claim 3, wherein the photo-curing temperature ranges from greater than or equal to 75 C. to less than 100 C.

Description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(1) Hereinafter, embodiments of the present invention will be described with reference to specific examples. Those skilled in the art will readily appreciate the advantages and utility of the present invention through the present description of the instant specification. Modifications and variations can be made without departing from the spirit of the present invention in implementing or applying the present invention.

(2) Materials

(3) 1. EVA particles, commodity model: UE2828, purchased from USI Corporation.

(4) 2. PVB film, product model: WINLITE, purchased from ChangChun PetroChemical., Co. Ltd.

(5) 3. PVB film, product model: Saflex DG, purchased from EASTMAN.

(6) 4. Photoinitiator: 4-(4-methylphenylthio) benzophenone, product type: Chemcure-BMS, purchased from Chembridge International Corp.

(7) 5. Photoinitiator: 2-isopropylthioxanthone, product model: Daracure ITX, purchased from Ciba company.

(8) 6. Photoinitiator: 2,4-diethyl thioxanthone, product model: KAYACURE DETX-S, purchased from Nippon Kayaku Co., Ltd.

(9) 7. Photoinitiator: diphenyl ethanedione dimethyl ketal, product model: Irgacure 651, purchased from BASF (Baden Aniline and Soda Factory).

(10) 8. Crosslink-assisting agent: Trimethylolpropane triacrylate, product model: Laromer TMPTA, purchased from BASE

(11) 9. Coupling agent: 3-(methacryloyloxy) propyltrimethoxysilane, product model: KBM-503, purchased from Shin-Etsu Chemical Co. Ltd.

(12) 10. Radical scavenger: bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, product model: Tinuvin 770, purchased from BASF.

(13) 11. UV absorber: 2,2-dihydroxy-4,4-dimethoxybenzophenone, product model: Uvinul 3049, purchased from BASF.

Examples 1 to 3: Laminated Glass Interlayer Films

(14) The EVA particles were first put into a stirring tank, and the stirring was continued for 6 minutes. Then, photoinitiators, crosslink-assisting agents, coupling agents, radical scavengers, and ultraviolet light absorbers were sequentially added according to the ratios shown in Table 1 below. After stirring for 15 minutes, a mixture was obtained.

(15) The MFR of the selected EVA particles was 28 g/10 min at 190 C. and the EVA particles contained 28 wt % vinyl acetate groups.

(16) Subsequently, the mixture was placed in a thermoforming machine and hot-pressed at a temperature of 110 C. for 1 minute to obtain a sample film, and the sample film was cut into a plurality of pieces of laminated glass interlayer films each having a size of 5 cm5 cm.

Comparative Example 1: Laminated Glass Interlayer Film

(17) The EVA particles were first put into a stirring tank, and the stirring was continued for 6 minutes. Then, photoinitiators, crosslink-assisting agents, coupling agents, radical scavengers, resin adhesives and ultraviolet light absorbers were sequentially added according to the ratios shown in Table 1 below. After stirring for 15 minutes, a mixture was obtained.

(18) Subsequently, the mixture was placed in a thermoforming machine and hot-pressed at a temperature of 110 C. for 1 minute to obtain a sample film, and the sample film was cut into a plurality of pieces of laminated glass interlayer films each having a size of 5 cm5 cm.

(19) TABLE-US-00001 TABLE 1 Example number Comparative Example 1 Example 2/3 Example 1 EVA UE2828 100 100 100 Photoinitiator Chemcure- 2 2 0 BMS Daracure ITX 0.5 0 0 KAYACURE 0 0.5 0 DETX-S Irgacure 651 0 0 2.5 Crosslink- Laromer.sup.(R) 2.5 2.5 2.5 assisting TMPTA agent Coupling agent KBM-503 0.3 0.3 0.3 Radical Tinuvin770 0.3 0.3 0.3 scavenger Ultraviolet Uvinul3049 0.3 0.3 0.3 light absorber

(20) Making Laminated Glasses with the Interlayer Films of Examples 1 to 3, and Comparative Example 1

(21) First, two pieces of glass sheets each having a size of 5 cm5 cm and a thickness of 5 mm were prepared, and a sheet of a laminated glass interlayer film (obtained in Examples 1 to 3 or Comparative Example 1) of the size of 5 cm5 cm is sandwiched between the glass sheets to obtain a laminated structure.

(22) For Examples 1 and 2 and Comparative Example 1, the laminated structure was then placed in a vacuum laminator. The laminated structure was heated at a lamination temperature of 140 C., and was continuously vacuumed for 3 minutes. 10 J of light was applied to the laminated structure at a photo-curing temperature of 140 C. The laminated structure was then taken out to complete the production of the laminated glass. For Example 3, the laminated structure was then placed in a vacuum laminator. The laminated structure was heated at a lamination temperature of 75 C., and was continuously vacuumed for 12 minutes. 10 J of light was applied to the laminated structure at a photo-curing temperature of 75 C. The laminated structure was then taken out to complete the production of the laminated glass.

(23) The production time required for each laminated glass, the time required for the EVA film to be exposed, and the thickness of the EVA film in the laminated glass are shown in Table 2 below. The time required to produce the laminated glass comprises the time required for lamination and the time for exposure.

Comparative Examples 2 and 3: Conventional Laminated Glass

(24) Comparative Example 2 used the aforementioned WINLITE as the interlayer film, and Comparative Example 3 used the Saflex DG of EASTMAN as the interlayer film.

(25) Two glass sheets of 5 cm5 cm in size and 5 mm in thickness were prepared, and an interlayer film having a size of 5 cm5 cm was sandwiched between the glass sheets to obtain a laminated structure. The laminated structure was pre-pressed as described in the technical data, and then placed into the high temperature and high pressure furnace for 4 hours, which completed the production of the laminated glass.

Test Example: Analysis of the Properties of Laminated Glasses

(26) 1. Gel Content:

(27) Analysis method: ASTM D2765-11.

(28) 2. Transmittance, Haze:

(29) Analysis method: ASTM D1003-11, with two clear glass sheets of 5 mm in thickness.

(30) 3. Delamination:

(31) Analysis method: ISO12543. Laminated glass products are placed at 100 C. for 2 hours in boiling water to inspect for delamination.

(32) TABLE-US-00002 TABLE 2 Property analysis results of Examples 1 to 3 and Comparative Examples 1 to 3 Comparative Comparative Comparative Example 1 Example 2 Example 3 Example 1 Example 2 Example 3 Time for 5 minutes 5 minutes 15 minutes 5 minutes 4 hours 4 hours laminated glass production Time for EVA 120 seconds 120 seconds 120 seconds 120 seconds film exposure Thickness of 0.4 mm 0.4 mm 0.4 mm 0.4 mm 0.38 mm 0.38 mm EVA film Crosslinking 75% 85% 87% 52% ratio Transmittance 80% 83% 88% 75% 93% 90% Haze 1.5% 0.9% 0.4% 20% 0.8% 1.1% Delamination Not Not Not Not Observed Observed observed observed observed observed

(33) As shown in the above Table 2, it was confirmed that a laminated glass comprising the interlayer film of Comparative Example 1 had a high haze and a low transmittance, which is a significant defect when implemented as a product of greater thickness such as an outfacing window of a building, a car glass, or a windshield. The high haze and low transmittance of the laminated glass product adversely affects the functionalities of such products. A laminated glass comprising the PVB film of Comparative Example 2 or Comparative Example 3 as the interlayer film is liable to delamination. The production time of this laminated glass extends to 4 hours, which is not conducive to mass production.

(34) In contrast to the results of the analysis shown in the above Table 2, the laminated glass comprising the interlayer film of Example 1, Example 2 or Example 3 was able to provide both a high transmittance and a low haze. An outfacing window of a building, a car glass, or a windshield made of the laminated glass comprising the interlayer film of Example 1, Example 2 or Example 3 significantly benefits by the low haze and high light transmittance. The production time required for the laminated glass of the present invention is only 5 minutes or less. Furthermore, the laminated glass comprising the interlayer film of Example 1, Example 2 or Example 3, which is high in crosslinking ratio, is capable of more specifically avoiding delamination problems.