JPH0331575B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a laminate, and particularly to a laminate that is suitable for application to a laminated window with a good appearance and is made by interposing a transparent film between two transparent plates, and furthermore, it relates to a laminate that is suitable for application to a laminated window with a good appearance, and furthermore, it relates to a laminate that is made by interposing a transparent film between two transparent plates and is suitable for application to a laminated window that has a good appearance. The present invention relates to a laminate suitable for obtaining a laminated window provided with functions. BACKGROUND OF THE INVENTION Laminated glass windows are used for transparent openings that require safety, such as windows of automobiles, trains, airplanes, etc., or some building windows. The basic structure of a laminated window is that a thermoplastic resin layer is sandwiched between transparent materials such as gas laminated plates, but a film is further interposed in order to impart further functionality to the laminated window. For example, there are methods of interposing a transparent film with excellent mechanical strength to prevent scattering, methods of interposing a transparent conductive film to prevent condensation, or methods of interposing a transparent film with excellent mechanical strength to prevent scattering, or methods of interposing a transparent conductive film to prevent condensation. A method has been proposed in which a film with a selective permeability function is interposed. However, a laminated window with a film interposed therebetween with a good appearance could not be obtained unless the film thickness was about 130 μm or more. As the thickness of the film is made thinner, the transparency of the laminated window becomes better, but when looking at the reflected image from the surface of the laminated window, fine irregularities occur in the image, making the image itself appear distorted, making it difficult to put into practical use. It was something that could not be offered. On the other hand, there is generally a method of applying thin film processing to the surface of the film in order to impart functionality to the surface of the film, but this thin film processing is often done in a vacuum container, improving processability and productivity (e.g. continuous production )
From this point of view, the thinner the film, the better. Therefore, if the film thickness is 130μm or less,
For example, if a laminated window with a good appearance could be manufactured using a film with a thin film thickness of 25 μm,
It becomes possible to obtain laminated windows with various functionalities. As a result of intensive research to achieve this objective, the present inventors prepared a film that satisfies specific heat shrinkage conditions and laminated it with thermoplastic resin layers sandwiched from both sides. The present inventors have discovered that by stacking the sheets between the plates, a laminated window with a better appearance can be obtained than when the sheets are laminated separately, and the present invention has been achieved. That is, the present invention provides polyvinyl butyral resin on both sides of a heat-shrinkable film, particularly a heat-shrinkable film whose film thickness d (μm) and heat shrinkage rate E (%) satisfy the following formula: E-0.006×d+0.75. and/or a laminate for laminated windows formed by laminating styrene-vinyl acetate copolymer resin layers, and a method for producing the same. A feature of the present invention is that by providing the film itself with heat-shrinkable properties, it is possible to reduce the unevenness of the reflected image that occurs during the manufacturing of laminated windows. By laminating them with rollers, etc., the appearance is noticeably uneven compared to a laminated window made by simply stacking a thermoplastic resin layer, a heat shrinkable film, a thermoplastic resin layer, and a transparent plate on a transparent plate. It consists in gaining what is reduced. There is another effect of laminating the thermoplastic resin layer, heat-shrinkable film, and thermoplastic resin layer in advance. When handling heat-shrinkable film by hand, no matter how carefully you handle it, the film is not under uniform tension and may break, or the film surface may become uneven, with thin canal-like lines appearing at the boundaries of the unevenness. . These streaks and broken marks are not a big concern when the heat-shrinkable film is used as is for laminated windows in an untreated state, but in order to impart functionality to the heat-shrinkable film, processing, such as If a product has been processed to have a selective light transmittance function, it has the disadvantage that streaks and broken marks that occur on the processed surface are likely to deteriorate and spread during durability tests. . By laminating the thermoplastic resin layer, the heat-shrinkable film, and the thermoplastic resin layer in advance using a roller, etc., it is possible to greatly reduce the streaks and folds of the heat-shrinkable film as described above. can. The thermal contraction rate E (%) of the film is the value at the processing temperature when manufacturing laminated windows, and the processing temperature is
The normal processing temperature is 120°C to 140°C, although it ranges from 100°C to 160°C. In addition, the thermal shrinkage rate of the film is determined by the mechanical direction (hereinafter abbreviated as MD) of the film,
Indicates the smaller value of the thermal shrinkage rate in the width direction (hereinafter abbreviated as TD). In order to obtain a good appearance, it is preferable that both MD and TD have similar heat shrinkage rates. The laminate can be manufactured by laminating a sheet of thermoplastic resin from an extrusion die on both sides of a heat-shrinkable film, or by laminating a sheet of thermoplastic resin on one side. There is a method of laminating heat-shrinkable film on both sides by attaching a molding film and unrolling the film that has already been rolled up. In either case, the surface of the thermoplastic resin to be bonded to the heat-shrinkable film should not be embossed or coated with sodium bicarbonate powder, which is commonly used to impart non-adhesive properties. On the embossed surface of the thermoplastic resin, if the heat-shrinkable film is thin, the unevenness caused by the embossing may be transferred onto the heat-shrinkable film, making it difficult to obtain a good appearance. The surface of the thermoplastic resin in contact with the transparent plate is preferably embossed. This is because when the thermoplastic resin comes into contact with the transparent plate on the non-embossed surface, it is difficult to uniformly laminate the resin without forming bubbles. Additionally, in such cases, a method of pouring another adhesive liquid resin to prevent the generation of air bubbles may be considered, but this increases the number of manufacturing steps for the laminated window, leading to an increase in cost. From the above, embossing is also good in that it eliminates the generation of bubbles and facilitates degassing. A laminate in which a thermoplastic resin layer, a heat-shrinkable film, and a thermoplastic resin layer are sequentially laminated has the following properties: In order to prevent the thermoplastic resins from adhering to each other when rolled,
It is preferable to further laminate a release film or attach sodium bicarbonate powder or the like to reduce the tackiness of the thermoplastic resin. Each component will be explained in detail below. Thermoplastic resins are those that have suitable adhesion to transparent plates, good transparency, and sufficient softness at laminate processing temperatures, such as polyvinyl butyral, synthetic rubber, styrene-butadiene rubber, and nitrile butadiene. Rubber, neoprene, polyisobutylene, polyisoprene, butyl rubber,
Examples include chlorinated rubber, polyacrylic acid ester, polyvinyl acetate, polyvinyl ether, polyvinyl chloride, polyethylene propylene copolymer, polyester copolymer, etc. In the present invention, polyvinyl butyral resin and/or ethylene-
Vinyl acetate copolymer resin is used. In order to improve the safety of the laminated window, the heat-shrinkable film may be a laminated unprocessed film, or may be a functionalized thin film. Film materials include polyethylene terephthalate resin, polyvinyl alcohol, polypropylene, polyethylene, polyvinyl chloride resin, polybutylene terephthalate resin, polycarbonate resin, acrylic resin, polyamide resin, and molded products of other resins. must have a certain rate. Examples of heat-shrinkable films imparting a transparent conductive function include thin films of indium oxide and tin oxide, tin oxide thin films, and thin films of metals such as gold, silver, copper, and aluminum. In addition, examples of metals that have a selective light transmittance function that makes it difficult for invisible heat rays of solar energy to pass through include gold, silver, copper, aluminum, nickel, palladium, tin, and alloys or mixtures of these metals. or a thin film of this metal with a dielectric layered on one or both sides.
Examples of the dielectric include titanium oxide, bismuth oxide, zinc sulfide, tungsten oxide, indium oxide, zirconium oxide, silicon oxide, and the like. At the stage of laminating the heat-shrinkable film used in the present invention, the thickness of the film is d (μm), and the heat shrinkage rate of the film at the processing temperature of the laminated window is E (%).
If so, it is required to satisfy the condition E-0.006×d+0.75. More preferably, it satisfies 100d10, particularly preferably 80d10. From the viewpoint of cost reduction of the film or productivity when adding functions, it is preferable that the thickness of the film is as small as possible. Furthermore, in order to ensure safety in the event of a collision, which is one of the characteristics required for laminated windows, it is not preferable for the film to be too thick. If the film is too thick,
It becomes difficult to absorb energy due to glass breaking and thermoplastic resin deformation. The thicker the film thickness of the heat-shrinkable film, the better the appearance even if the heat shrinkage rate is small.
When the film thickness is 130 μm or more, a good product can be obtained regardless of the film's heat shrinkage characteristics, but as the film thickness becomes thinner, a good appearance cannot be obtained unless the film's heat shrinkage value is increased. Good results can be obtained when the above conditional expressions are satisfied. Hereinafter, the present invention will be specifically explained with reference to Examples. Example 1 and Comparative Example 1 A film of indium oxide and tin oxide was provided on a biaxially stretched polyethylene terephthalate film (thickness: 50 μm) having a visible light transmittance of 86%. Film production is
A target of In ₂ O ₃ ·SnO ₂ (SnO ₂ is 5 wt% in total) was heated 2× in a mixed gas of Ar/O ₂ (O ₂ 2%).
A film with a thickness of about 500 Å was obtained by RF sputtering under a vacuum of 10 ^-3 Torr. The heat shrinkage rates of this surface-treated polyethylene terephthalate film at 120°C were 2.0% and 1.8% for ND and TD, respectively. A 380 μm thick polyvinyl butyral film was laminated on both sides of the processed polyethylene terephthalate film using a laminator. The polyvinyl butyral sheet was embossed on one side, and the surface to be attached to the heat-shrinkable film was non-embossed and smooth, and had been made into a roll with a release film attached in advance. The laminate was further sandwiched between two 2 mm thick ordinary glass plates, the air was removed under reduced pressure, and then heated at 90°C under a pressure of 2.
Preliminary bonding was performed by treating with Kg/cm ² for 30 minutes. Thereafter, it was left in an autoclave at 120° C. and under a pressure of 14 Kg/cm ² for 40 minutes. Thereafter, the glass was cooled to room temperature while applying pressure to obtain a laminated window. The resulting laminated window had a good appearance, and no unevenness or distortion of the reflected image was observed. On the other hand, lamination was carried out under exactly the same conditions except that films with heat shrinkage rates of 0.2% and 0% for MD and TD were used, respectively, and the appearance of the resulting laminated window was poor with irregularities in the reflected image. Examples 2 to 7 and Comparative Examples 2 to 6 On transparent biaxially stretched polyethylene terephthalate films having various heat shrinkage rates and film thicknesses,
A 120Å silver/copper (copper content 11wt%) alloy film is provided.
Furthermore, a film having a selective light transmission function was obtained by sequentially laminating titanium oxide films with a thickness of 100 Å. The titanium oxide film was obtained by a hydrolysis method of tetrabutyl titanate. The film had a visible light transmittance of 79% and a near infrared transmittance of 41%. A polyvinyl butyral film with a thickness of 380 μm and a glass plate with a thickness of 2 mm were laminated on both sides of the film. Thereafter, after removing the air by reducing the pressure, preliminary bonding was performed at 90℃ for 60 minutes under a pressure of 1Kg/ ^cm2 , and then at 120℃ in an autoclave.
Main adhesion was performed by leaving it for 50 minutes under a pressure of 12 kg/cm ² . Thereafter, after cooling to room temperature, the pressure was released and the laminated window sample was taken out. The heat shrinkage rate and thickness of the film at 120°C, and the appearance of the laminated window are summarized in Table 1. Example 8 On a transparent biaxially stretched polyethylene terephthalate film having a heat-shrinkable film thickness of 75 μm,
A 120Å silver/copper (copper content 11wt%) alloy film is provided.
Furthermore, a film having a selective light transmission function was obtained by sequentially laminating titanium oxide films with a thickness of 100 Å. The titanium oxide film was obtained by a hydrolysis method of tetrabutyl titanate. The film had a visible light transmittance of 79% and a near infrared transmittance of 41%. Ethylene/vinyl acetate copolymer resin films (manufactured by Takeda Pharmaceutical Co., Ltd., trade name: "DUMILAN") each having a thickness of 250 μm and glass plates having a thickness of 2 mm were laminated on both sides of the film. Then, after removing the air by reducing the pressure, preliminary bonding was performed at 85℃ and under a pressure of 1Kg/ ^cm2 for 30 minutes, and then in an autoclave.
Main adhesion was carried out by leaving it for 30 minutes at 120°C and under a pressure of 10 kg/cm ² . Thereafter, after cooling to room temperature, the pressure was released and the laminated window sample was taken out. 120℃ for film
The thermal shrinkage rate, film thickness, and appearance of the laminated window are listed in Table 1.

[Table] Example 9 Tungsten oxide with a thickness of 150 Å, silver with a thickness of 100 Å, and tungsten oxide with a thickness of 200 Å were sequentially laminated on a biaxially stretched polyethylene terephthalate film (film thickness: 25 μm). Tungsten oxide was provided by reactive sputtering using tungsten as a target, and silver was provided by sputtering using tungsten as a target. The heat shrinkage rates of the surface-treated film were 3.1% and 2.8% for MD and TD, respectively. Polyvinyl butyral mixed and melted with a plasticizer in a melter was extruded, and polyvinyl butyral, a thermoplastic resin having a thickness of 380 μm, formed into a film by a calendar method was laminated on both sides of the heat-shrinkable film using a laminator. The surface of the polyvinyl butyral sheet to be bonded to the heat shrink film was made as smooth as possible. After lamination, the other side of the polyvinyl butyral sheet was embossed, a release film was applied, and the sheet was wound onto a roll. The laminate was sandwiched between 2 mm thick glass plates and heated at 90°C under a pressure of 2 kg/cm in an autoclave to remove air between the glass plate and the thermoplastic resin layer under reduced pressure.
After pre-bonding at cm ² for 30 minutes, the temperature was increased to 120°C.
Main adhesion was carried out for 40 minutes at a pressure of 14 kg/cm ² . Then, after cooling to room temperature, the pressure was released and the sample was taken out. The resulting laminated window sample had a good appearance. Comparative Example 7 In Example 5, instead of preparing a film in which the film was sandwiched between polyvinyl butyral films from both sides and laminated, the polyvinyl butyral film, the film, and the polyvinyl A butyral film and a 2 mm thick glass plate were laminated. The appearance of the laminate produced under otherwise identical conditions was somewhat uneven, and the evaluation was △.

[Brief explanation of drawings]

The drawing is an example of the manufacturing method of the present invention. 1, 1' are die, 2, 2' are thermoplastic resin films, 3 are heat shrinkable films, 4, 4' are rolls,
5 and 5' indicate embossing rolls.

Claims (1)

[Scope of Claims] 1. A laminate comprising at least a thermoplastic resin layer, a heat-shrinkable film, and a thermoplastic resin layer, the thermoplastic resin being polyvinyl butyral resin and/or ethylene-vinyl acetate. A laminate for laminated windows made of copolymer resin. 2. Claim 1, wherein the thermoplastic resin layer surface facing the heat-shrinkable film surface is a non-embossed surface.
Laminate for laminated windows. 3. A laminated body for laminated windows, which consists of forming a sheet of a thermoplastic resin layer made of polyvinyl butyral resin and/or ethylene-vinyl acetate copolymer resin, and then simultaneously laminating the thermoplastic resin sheets from both sides of a heat-shrinkable film. manufacturing method.