Door window for vehicles

Abstract

Door window for a vehicle, comprising: a laminated glass comprising a first glass plate, a first adhesive layer, an infrared reflection film, a second adhesive layer and a second glass plate, laminated in this order, wherein the infrared reflective film comprises a laminate in which 100 or more layers of at least two kinds of resin layers A and B, each made of resins A and B, having different refractive indices are laminated, and the infrared reflective film has a heat shrinkage rate of greater than 0.6% and less than 1.2% in one direction before the laminated glass is manufactured, in which the heat shrinkage rate becomes maximum, and has a heat shrinkage rate of greater than 0.6% and less than 1.2% in a direction perpendicular to the direction in which the heat shrinkage rate becomes maximum, wherein the heat shrinkage rate of the infrared reflective film in a given direction is a shrinkage rate of a length in the given direction before and after holding the infrared reflective film at 150 °C for 30 minutes, wherein the infrared reflection film is obtained by a method comprising (a) a step of producing an unstretched laminate in which layer A and layer B are alternately laminated, the unstretched laminate having the same number of laminated layers as in a final laminate although the layer thickness is different from the final laminate, (b) a step of stretching the unstretched laminate obtained in step (a) and adjusting the layer thickness to produce a laminate precursor, and optionally (c) a step of applying a heat treatment to the laminate precursor after step (b) to obtain a laminate whose heat shrinkage rate is adjusted to satisfy the above heat shrinkage rates, wherein, in an area where the laminated glass is visible when the laminated glass is mounted on the vehicle, an outer periphery of the infrared reflective film is positioned in a front view within a range of up to 10 mm inward from an outer periphery of the laminated glass, wherein each of the first and second glass plates is formed of transparent glass, and wherein, in a region where the laminated glass is visible when the laminated glass is mounted on the vehicle, each corner of an outer periphery of the infrared reflective film has a curvature in a front view, and a minimum radius of curvature of the outer periphery is greater than or equal to 8 mm; and / or wherein the first adhesive layer and the second adhesive layer have a heat shrinkage rate of greater than or equal to 2% and less than or equal to 8% in a direction in which the heat shrinkage rate becomes maximum, and a heat shrinkage rate of greater than or equal to 2% and less than or equal to 8% in a direction perpendicular to the direction in which the heat shrinkage rate becomes maximum, wherein the heat shrinkage rate of the first adhesive layer and the second adhesive layer in a predetermined direction is a shrinkage rate of a length in the predetermined direction before and after holding the first adhesive layer and the second adhesive layer at 50°C for 10 minutes, and wherein the direction in which the heat shrinkage rate of the infrared reflective film becomes maximum is orthogonal to the direction in which the heat shrinkage rate of the first adhesive layer and the second adhesive layer becomes maximum; and / or where a value obtained by dividing the heat shrinkage rate in the direction in which the heat shrinkage rate of the infrared reflective film becomes maximum, obtained by an average of the heat shrinkage rates of the first adhesive layer and the second adhesive layer in respective maximum directions is within a range of greater than or equal to 0.1 and less than or equal to 0.4.

Description

[Technical field]

[0001] The present invention relates to a door glass for vehicles, particularly to a door glass for vehicles made of a laminated glass using an infrared reflection film. [State of the art]

[0002] To reduce the load on a vehicle's air conditioning system and improve passenger comfort, a vehicle door glass using laminated glass with thermal insulation properties has been conventionally known. Among such glasses, a laminated glass has been proposed that includes an infrared reflective film sandwiched between two glass plates by means of an adhesive layer.

[0003] For example, laminated glass is manufactured by laminating a glass plate, an adhesive layer, an infrared reflective film, another adhesive layer, and another glass plate in this order, and then heating and pressing the entire laminate to integrate them. In the manufacture of such laminated glass, there have been problems in that uneven pressing caused by uneven thickness of the adhesive layers and / or a difference in heat shrinkage rate between the film and the adhesive layers causes uneven warpage and / or wrinkles to occur on the film, thereby deteriorating the appearance; and measures to solve these problems have been investigated.

[0004] For example, Patent Document 1 discloses a technique of a multi-layer laminated film having a function of reflecting infrared rays by interference reflection, wherein the heat shrinkage stress of the film is set so as to suppress unevenness in appearance by alternately laminating resin layers having different refractive indices and adjusting the thickness of each layer to be laminated.

[0005] Furthermore, Patent Document 2 also discloses a laminated glass in which one of the heat shrinkage rate, the elastic modulus, and the elongation of the infrared reflection film is adjusted to be within a predetermined range, so that wrinkles on the film, which tend to occur in edge parts of the main surfaces, are suppressed, particularly in the case of using glass plates curved by bending.

[0006] The techniques of Patent Document 1 and Patent Document 2 aim to prevent deterioration of the appearance within the main surfaces of a laminated glass, and these are effective to a certain extent. However, in the case of a door glass for vehicles, it is known that the edge portions and end surfaces of the main surfaces (hereinafter referred to as the end portions) are particularly conspicuous when the door glass is moved upward or downward, and the appearance of the end portions poses a problem.

[0007] For example, in order to protect the end portions of the infrared reflective film, in some cases, the outer periphery of the film is arranged inward in plan view relative to the outer periphery of the glass panel. In this case, especially when the door glass is moved up or down, a problem occurs that the color tone of the end portions of the door glass changes and appears to shimmer. On the other hand, in the case of disposing the outer periphery of the film in plan view close to the outer periphery of the glass panels to improve the appearance, another problem occurs in that the infrared reflective film undergoes heat shrinkage due to heating in the manufacturing process, which causes the adhesive layers to be pulled toward the center of the main surfaces and thereby causes deterioration of the appearance at the end portions of the glass.

[0008] However, as described above, in Patent Document 1 and Patent Document 2, appearance deterioration on the main surfaces of the laminated glass caused by the infrared reflective film is suppressed; however, the problem of shimmering at the end portions when the glass is used as a door glass of a vehicle and the appearance problem caused by pulling of the adhesive layers are not solved. Patent Document 3 describes a wrinkle-resistant infrared reflective film and non-planar laminated articles made therefrom. Patent Document 4 describes a multilayer laminated film that solves the problem of defects in the external appearance of a molded article; and a molded article thereof. [Prior art documents][Patent documents] Patent document 1: WO 2013 / 137288 A1 Patent Document 2: Japanese Laid-Open Patent Application JP 2010 180 089 A Patent document 3: US 6,797,396 B1 Patent document 4: US 2015 / 0064428 A1 [Summary of the invention][Problem to be solved by the invention]

[0009] It is an object of the present invention to provide a door glass for vehicles made of a laminated glass using an infrared reflection film, which has excellent heat insulation and good appearance, and in which occurrence of deteriorated appearance particularly at the end portions is suppressed. [Means of solving the problems]

[0010] According to one embodiment of the present invention, a door glass for a vehicle comprises a laminated glass having a first glass plate, a first adhesive layer, an infrared reflective film, a second adhesive layer, and a second glass plate laminated in this order. The infrared reflective film comprises a laminate in which 100 or more layers of at least two types of resin layers A and B, each made of resins A and B having different refractive indices, are laminated, and, before the laminated glass is manufactured, has a heat shrinkage rate of greater than 0.6% and less than 1.2% in a direction in which the heat shrinkage rate becomes maximum, and a heat shrinkage rate of greater than 0.6% and less than 1.2% in a direction perpendicular to the direction in which the heat shrinkage rate becomes maximum.wherein the heat shrinkage rate of the infrared reflective film in a predetermined direction is a shrinkage rate of a length in the predetermined direction before and after holding the infrared reflective film at 150°C for 30 minutes, wherein the infrared reflective film is obtained by a process comprising (a) a step of preparing an unstretched laminate in which layer A and layer B are alternately laminated, the unstretched laminate having the same number of laminated layers as in a final laminate to be obtained although the layer thickness is different from the final laminate, (b) a step of stretching the unstretched laminate obtained in step (a) and adjusting the layer thickness to produce a laminate precursor, and optionally (c) a step of applying a heat treatment to the laminate precursor after step (b) to obtain a laminate,whose heat shrinkage rate is adjusted to meet the above heat shrinkage rates. In a region where the laminated glass is visible when the laminated glass is mounted on the vehicle, the outer periphery of the infrared reflective film is positioned within a range of up to 10 mm inward from the outer periphery of the laminated glass in a front view, wherein each of the first and second glass plates is formed of transparent glass. In a region where the laminated glass is visible when the laminated glass is mounted on the vehicle, each corner of an outer periphery of the infrared reflective film has a curvature in a front view, and a minimum radius of curvature of the outer periphery is greater than or equal to 8 mm; and / or the first adhesive layer and the second adhesive layer have a heat shrinkage rate of greater than or equal to 2% and less than or equal to 8% in one direction,in which the heat shrinkage rate becomes maximum, and a heat shrinkage rate of greater than or equal to 2% and less than or equal to 8% in a direction perpendicular to the direction in which the heat shrinkage rate becomes maximum, wherein the heat shrinkage rate of the first adhesive layer and the second adhesive layer in a predetermined direction is a shrinkage rate of a length in the predetermined direction before and after holding the first adhesive layer and the second adhesive layer at 50°C for 10 minutes, and wherein the direction in which the heat shrinkage rate of the infrared reflective film becomes maximum is orthogonal to the direction in which the heat shrinkage rate of the first adhesive layer and the second adhesive layer becomes maximum; and / or a value obtained by dividing the heat shrinkage rate in the direction in which the heat shrinkage rate of the infrared reflective film becomes maximum,obtained by an average of the heat shrinkage rates of the first adhesive layer and the second adhesive layer in respective maximum directions is within a range of greater than or equal to 0.1 and less than or equal to 0.4. [Effects of the invention]

[0011] According to the present invention, there can be provided a door glass for vehicles made of a laminated glass using an infrared reflection film, which has excellent heat insulation and good appearance, and in which occurrence of deteriorated appearance particularly at the end portions is suppressed.

[0012] It should be noted that although a laminated glass using an infrared reflection film is also known for a so-called orange peel problem, which is a phenomenon in which the outline of a reflected image looks uneven, according to the present invention, the occurrence of the orange peel can also be suppressed. [Brief description of the drawings] Fig. 1 is an example of a front view of a laminated glass constituting a door glass for vehicles in an embodiment according to the present invention; Fig. 2 is a cross-sectional view of the laminated glass used in the Fig. 1, along a line XX; and Fig. 3 is a side view of an automobile including the door glass for vehicles used in the Fig. 1 is shown. [Mode for carrying out the invention]

[0013] Embodiments according to the present invention will be described below. It should be noted that the present invention is not limited to these embodiments, and these embodiments may be changed or modified without departing from the spirit and scope of the present invention.

[0014] A door glass for vehicles (hereinafter simply referred to as "door glass") according to an embodiment comprises a first glass plate, a first adhesive layer, an infrared reflective film, a second adhesive layer, and a second glass plate laminated in this order to form a laminated glass, wherein the structure of the infrared reflective film satisfies the following requirements (1) to (3). (1) The infrared reflective film comprises a laminate in which 100 or more layers of at least two kinds of resin layers A and B, each made of resins A and B, having different refractive indices are laminated, and satisfies the following heat shrinkage rates before the production of laminated glass, the infrared reflective film being obtained by a process comprising (a) a step of preparing an unstretched laminate in which layer A and layer B are alternately laminated, the unstretched laminate having the same number of laminated layers as in a final laminate to be obtained although the layer thickness is different from the final laminate, (b) a step of stretching the unstretched laminate obtained in step (a) and adjusting the layer thickness to produce a laminate precursor,and optionally (c) a step of applying a heat treatment to the laminate precursor after step (b) to obtain a laminate whose heat shrinkage rate is adjusted to satisfy the following heat shrinkage rates., (2) The infrared reflective film has a heat shrinkage rate of greater than 0.6% and less than 1.2% in a direction where the heat shrinkage rate is maximum, and a heat shrinkage rate of greater than 0.6% and less than 1.2% in a direction perpendicular to the maximum direction. The heat shrinkage rate of an infrared reflective film in a given direction is the length shrinkage rate in the given direction before and after the infrared reflective film is held at 150°C for 30 minutes. (3) In an area where the laminated glass is visible when the laminated glass is mounted on a vehicle, the outer periphery of the infrared reflective film is positioned within a range of up to 10 mm inward from the outer periphery of the laminated glass in a front view.

[0015] An infrared reflective film that satisfies the requirement of (1) has infrared reflectivity caused by interference reflection. In an infrared reflective film that satisfies the requirement of (2), pulling of the adhesive layers when the laminated glass is manufactured can be suppressed, and in an infrared reflective film that satisfies the requirement of (3), shimmering when present in the laminated glass can be suppressed, and deteriorated appearance at the end portions can be suppressed. Consequently, a door glass can be obtained that has excellent heat insulation and good appearance, and in which deteriorated appearance, particularly at the end portions, is suppressed. The door glass according to the embodiment will be described below with reference to the drawings.

[0016] The Fig. 1 is a front view of a laminated glass forming a door glass for vehicles according to an embodiment; the Fig. 2 is a cross-sectional view of the laminated glass used in the Fig. 1, along a line XX; and the Fig. 3 is a side view of an automobile including the door glass for vehicles used in the Fig. 1 is shown.

[0017] In this specification, "upper," "lower," "front," and "rear" refer to the upper, lower, front, and rear sides of the door glass when the door glass is mounted on the vehicle, respectively. The "vertical direction" of the door glass indicates the vertical direction with respect to the door glass when the door glass is mounted on the vehicle, and the direction orthogonal to the vertical direction is referred to as the "vehicle width direction."

[0018] In the present specification, each of the first glass panel, the first adhesive layer, the infrared reflection film, the second adhesive layer, and the second glass panel; and the door glass has two main surfaces opposite to each other and has end surfaces connecting the two main surfaces. In the present specification, an edge part of a main surface refers to an area having a certain width from the outer periphery toward the center of the main surface. The edge parts and the end surfaces of both main surfaces are referred to as end parts. In the present specification, the outer edge part viewed from the center of the main surface is referred to as the outer side, and the central part viewed from the outer edge part of the main surface is referred to as the inner side.In this specification, "substantially the same shape" and "substantially the same dimensions" refer to a state of an object in which it can be considered to have the same shape and dimensions when viewed by a person. In other cases, "substantially" has a corresponding meaning as above. Furthermore, a numerical range indicated by "up to" includes an upper limit and a lower limit.

[0019] A laminated glass 10 used as a door pane, which is inserted into the Fig. 1 and Fig. 2 (hereinafter also referred to as the "door glass 10") includes a first glass panel 1, a first adhesive layer 3, an infrared reflection film 5, a second adhesive layer 4, and a second glass panel 2, which are laminated in this order. The first glass panel 1, the first adhesive layer 3, the second adhesive layer 4, and the second glass panel 2 have main surfaces with substantially the same shape and dimensions.

[0020] In the laminated glass 10, the shape of the main surfaces of the infrared reflection film 5 is substantially similar to the shape of the main surfaces of the first glass plate 1. In an area where the laminated glass 10 is visible in a front view when the laminated glass 10 is mounted on the vehicle (hereinafter referred to as "visible area"), the outer periphery (in the Fig. 1 with a one-dot chain line) of the infrared reflection film 5 is positioned within a range of up to 10 mm inward from the outer periphery of the laminated glass 10 in a front view.

[0021] An automobile 100, which in the Fig. 3, the laminated glass 10 shown in the Fig. 1. In the automobile 100, each of the front door S and the rear door S includes a door panel 20 and the door glass 10 installed in the door panel 20 and movable upward and downward. Fig. 3, when the door glass 10 has been moved to the top of the front door S, namely, when the window is closed, the door glass 10 is denoted by a dashed line. Further, when the door glass 10 has been moved downward by a distance L from the top position, the door glass 10 is denoted by a solid line and a dashed line.

[0022] In the automobile 100, a line connecting the upper ends of the front and rear of the door panel 20, namely, a line connecting the lower ends of an opening of the vehicle, is referred to as a belt line VL. Fig. Fig. 1 shows a position of the belt line VL along the door glass 10 when the door glass 10 mounted on the automobile 100 has been moved all the way up (when the door glass is completely closed). In the present description, the visible area in the door glass 10 is shown in Fig. Fig. 1, a region positioned above the belt line VL in a state where the door glass 10 is mounted on the automobile 100 and the door glass 10 is moved all the way up is an invisible region. A region positioned below the belt line VL in the state is an invisible region.

[0023] The Fig. 3 shows that no end surface of the door glass 10 is visible in a state where the window is closed, whereas part of the end surfaces become visible by opening the window. In the door glass 10, at least in a state where the door glass 10 is mounted on the automobile 100 and the door glass 10 is moved all the way up, if the above requirement of (3) is satisfied, the glare in a region positioned above the belt line VL can be suppressed. The components of the door glass 10 will be described below. [Infrared reflective film]

[0024] The infrared reflective film 5 in the door glass 10 satisfies the above requirements of (1) to (3). It is further preferable that the infrared reflective film 5 also satisfies one or both of the following requirements (4) and (5). (4) The infrared reflective film has a thickness of less than or equal to 120 µm. (5) The infrared reflective film has a minimum radius of curvature of greater than or equal to 8 mm in a front view in an area where the laminated glass is visible when the laminated glass is mounted on the vehicle.

[0025] By satisfying the requirement of (1), the infrared reflection film comprises a laminate in which 100 or more layers of resin layers having different refractive indices are laminated. By incorporating the laminate, the infrared reflection film 5 has infrared reflectivity. The infrared reflection film 5 may be formed only with the laminate or may optionally include another layer such as a protective layer or the like described later, as long as the effects of the present invention are not impaired. The another layer in the infrared reflection film is preferably made of a resin in view of durability.

[0026] Regarding the requirement of (1), in the infrared reflective film 5, the number of kinds of resin layers constituting the laminate and having different refractive indices is greater than or equal to two kinds, preferably greater than or equal to two kinds and less than or equal to four kinds, and more preferably two kinds in view of ease of manufacture. In the case of using two kinds of resin layers having different refractive indices, a resin layer having a relatively higher refractive index is set as the higher refractive index layer, and a resin layer having a relatively lower refractive index is set as the lower refractive index layer. In this case, the laminate is usually formed by alternately laminating the higher refractive index layer and the lower refractive index layer.

[0027] The refractive index in the resin layer is expressed as the refractive index at a wavelength of 589 nm, which is measured using a sodium D-line as a light source. The refractive index of the higher refractive index layer is preferably within a range of 1.62 to 1.70, and the refractive index of the lower refractive index layer is preferably within a range of 1.50 to 1.58. Furthermore, the difference in refractive index between the higher refractive index layer and the lower refractive index layer is preferably within a range of 0.05 to 0.20, and more preferably within a range of 0.10 to 0.15.

[0028] The refractive index of a resin layer can be adjusted by appropriately adjusting the type of resin, the type of functional group or skeleton in the resin, and the content of the resin. As the resin constituting a resin layer, a thermoplastic resin is advantageous, and for example, a polyolefin, alicyclic polyolefin, polyamide, aramid, acrylic resin, polyvinyl chloride, polyvinylidene chloride, polystyrene, styrene copolymer, polycarbonate, polyester, polyethersulfone, polyetheretherketone, modified polyphenylene ether, polyphenylene sulfide, polyetherimide, polyimide, polyarylate, fluorine-containing resin, and the like can be mentioned.

[0029] From these resins, two or more types of resins having different refractive indices are selected, and resin layers formed from the selected resins are laminated according to the above-described configuration to form a laminate. It should be noted that when resins having different refractive indices are selected, it is advantageous to select a combination of resins comprising the same repeating units from the viewpoints of interlayer adhesion and easy formation of a laminate structure with high accuracy. Of the above-described resins, a polyester is preferred in view of strength, heat resistance, and transparency, and it is preferable to select a combination of polyesters comprising the same repeating units.As the polyester to be selected, a polyester produced by using an aromatic dicarboxylic acid, an aliphatic dicarboxylic acid, a diol or a derivative thereof is preferred.

[0030] As the polyester to be selected, there may be mentioned polyethylene terephthalate, polyethylene terephthalate copolymer, polyethylene naphthalate, polyethylene naphthalate copolymer, polybutylene terephthalate, polybutylene terephthalate copolymer, polybutylene naphthalate, polybutylene naphthalate copolymer, polyhexamethylene terephthalate, polyhexamethylene terephthalate copolymer, polyhexamethylene naphthalate, polyhexamethylene naphthalate copolymer, and the like. It is preferable to use one or more types of polyesters selected from the polyesters described above.

[0031] Of these, as the resins constituting resin layers having different refractive indices, a combination comprising at least one type selected from a polyethylene terephthalate (hereinafter referred to as "PET") and a polyethylene terephthalate copolymer (hereinafter referred to as "PET copolymer") is preferred. In the case of forming a laminate by alternately laminating two types of resin layers, it is preferable that, for example, one is a resin layer made of a PET and the other is a resin layer made of a PET copolymer, or is a resin layer formed with at least two types of resins selected from PET and PET copolymers (hereinafter referred to as "blended PET").

[0032] A PET copolymer is composed of ethylene terephthalate units, which are the same repeating units as PET, and repeating units having other ester bonds (hereinafter referred to as "the other repeating units"). As the proportion of the other repeating units (hereinafter referred to as "copolymerization amount"), it is preferable that the proportion be greater than or equal to 5 mol% in view of the need to obtain a different refractive index, and less than or equal to 90 mol% in view of the need to achieve adhesion between layers and excellent precision and uniformity of the thickness of each layer due to a small difference in heat flow properties. The proportion is more preferably greater than or equal to 10 mol% and less than or equal to 80 mol%.

[0033] It should be noted that in the case where a blended PET is a mixture of a PET and a PET copolymer or a mixture of two or more kinds of PET copolymers, it is preferable to blend the components so that the content of the other repeating units in the blend is substantially identical to the amount of the copolymer in the PET copolymer.

[0034] It is preferable that the absolute value of the difference in glass transition temperature between the resin layers with different refractive indices be less than or equal to 20°C. If the absolute value of the difference in glass transition temperature is higher than 20°C, the thickness uniformity in the formation of an infrared reflective film comprising the laminate becomes insufficient, and variation in infrared reflectance may occur. Furthermore, a problem such as excessive stretching is likely to occur in the formation of an infrared reflective film comprising the laminate.

[0035] It is preferable that a blended PET includes, as the other repeating units, repeating units derived from spiroglycol, which is a diol, as a raw material. Hereinafter, a repeating unit derived from a raw material component is referred to by the name of the raw material compound and the associated term "unit." For example, a repeating unit derived from spiroglycol is referred to as a "spiroglycol unit." A blended PET containing spiroglycol units means that the blended PET contains a PET copolymer containing the spiroglycol units. A blended PET may be formed only with a PET copolymer having spiroglycol units, or it may be a mixture of the PET copolymer and a PET.In the following description, a blended PET containing units of a specific compound means the same as a blended PET containing spiroglycol units. A blended PET containing spiroglycol units is preferred due to a small difference in glass transition temperature with a PET.

[0036] It is preferable for a blended PET to contain cyclohexanedicarboxylic acid units in addition to spiroglycol units as the other repeating units. A blended PET containing spiroglycol units and cyclohexanedicarboxylic acid units has a small difference in glass transition temperature with PET and a large difference in refractive index with PET, and is therefore likely to exhibit very good infrared reflectivity when used in the laminate.

[0037] In the case where a mixed PET contains spiroglycol units and cyclohexanedicarboxylic acid units, it is preferable that the copolymerization amount of the spiroglycol units is 5 mol% to 30 mol% and the copolymerization amount of the cyclohexanedicarboxylic acid units is 5 mol% to 30 mol%.

[0038] A form of blended PET containing cyclohexanedimethanol units as the other repeating units is also preferred. A blended PET containing cyclohexanedimethanol units is preferred due to a small difference in glass transition temperature with a PET.

[0039] In the case where a blended PET contains cyclohexanedimethanol units, the copolymerization amount of cyclohexanedimethanol units is preferably greater than or equal to 15 mol% and less than or equal to 60 mol% from the viewpoint of compatibility between infrared reflectance and interlayer adhesion. It should be noted that isomers of cyclohexanedimethanol include the cis isomer and the trans isomer as geometric isomers, and the chair conformation and the boat conformation as conformational isomers.Therefore, a blended PET containing cyclohexanedimethanol units does not tend to become oriented crystals even when stretched with a PET; it has very good infrared reflectivity; it is less likely to change its optical properties, which would be caused by prior heat exposure; and it is less likely to generate defects during film formation.

[0040] The intrinsic viscosity (IV) of a PET and a blended PET used as described above is preferably 0.4 to 0.8, and more preferably 0.6 to 0.75, in view of film formation stability.

[0041] Combinations of PETs and blended PETs have been described above. In the present invention, combinations are not limited to those described above, and various blended PETs can be combined depending on the desired properties. In such a case, it is preferable that the types of units constituting the blended PETs are identical, and the compositions of the repeating units are different.

[0042] By laminating 100 or more resin layers having different refractive indices in this way, the laminate has a function of reflecting infrared rays by interference reflection. The number of laminated layers in the laminate is not particularly limited as long as it is greater than or equal to 100 layers. It is preferable to set the number appropriately within a range where the film thickness of the infrared reflection film 5 satisfies the requirement of (4). To improve infrared reflectivity, the number of resin layers is preferably 400 or more layers, and more preferably 600 or more layers. The upper limit of the number of laminated layers in the laminate is preferably about 5000 layers in view of meeting the preferred upper limit of the thickness of the infrared reflection film 5.

[0043] The number of laminated resin layers and the thickness of each resin layer included in the laminate are designed based on the refractive index of each resin layer to be used and depending on the required infrared reflectance. For example, in the case of using layer A and layer B as two resin layers with different refractive indices according to the thickness distribution, it is preferable that the optical thicknesses of layer A and layer B adjacent to each other satisfy the following formula (i): λ=2(nAdA+nBdB) where λ is the reflected wavelength; n A represents the refractive index of layer A; d A represents the thickness of layer A; n B represents the refractive index of layer B; and d B represents the thickness of layer B.

[0044] It is also preferable that the layer thickness distribution satisfies the following formula (ii) simultaneously with the formula (i). nAdA=nBdB

[0045] By distributing the layer thickness so that both (i) and (ii) are satisfied, even-order reflections can be eliminated. Consequently, for example, the average reflection at wavelengths from 850 nm to 1200 nm can be increased, while the average reflection at wavelengths from 400 nm to 700 nm is reduced. Thus, an infrared reflective film 5 can be obtained that is transparent and has excellent thermal energy insulation properties.

[0046] It is also preferable to use a structure of 711711 (US Patent No. 5,360,659) as a layer thickness distribution in addition to formulas (i) and (ii). The structure of 711711 is a laminate structure in which six layers of layers A and layers B laminated in the order of ABABAB form a repeating unit, and the ratios of the optical thicknesses in the unit are set to 711711. A layer thickness distribution according to the structure of 711711 eliminates higher-order reflections. Consequently, for example, the average reflectance at wavelengths from 850 nm to 1400 nm can be increased, while the average reflectance at wavelengths from 400 nm to 700 nm is decreased.It is also preferable to have a layer thickness distribution in which a layer thickness distribution satisfying both formulas (i) and (ii) simultaneously is used for reflection within a range of 850 nm to 1200 nm; and a layer thickness distribution of the structure of 711711 is used for reflection within a range of 1200 nm to 1400 nm. By using such a layer thickness structure, light can be efficiently reflected with a smaller number of laminated layers.

[0047] As the layer thickness distribution, a layer thickness distribution in which the layer thickness increases or decreases from one surface to the other surface of the film; a layer thickness distribution in which the layer thickness increases and then decreases from one surface to the film center of the film; a layer thickness distribution in which the layer thickness decreases and then increases from one surface to the film center of the film; or the like is preferable. As the manner of change in layer thickness in a distribution, it is preferable that it is a continuous change, which may be a linear sequence, a geometric sequence, or a differential sequence; or a change in which 10 layers to 50 layers have almost the same thickness and this thickness changes gradually.

[0048] It should be noted that the infrared reflective film 5 may have a resin layer with a layer thickness greater than or equal to 3 μm as a protective layer on both surfaces of the laminate. The layer thickness of the protective layer is preferably greater than or equal to 5 μm, and more preferably greater than or equal to 10 μm. By increasing the layer thickness of the protective layer, an effect of suppressing flow marks and suppressing waviness in the transmission and reflection spectrum can be obtained.

[0049] Regarding the requirement of (4), it is preferable that the infrared reflection film 5 has a thickness of less than or equal to 120 μm. When the thickness of the infrared reflection film 5 is less than or equal to 120 μm, the degassing performance in the production of the laminated glass is good. Further, it is preferable that the infrared reflection film 5 has a thickness of greater than or equal to 80 μm. The infrared reflection film 5 with a thickness of greater than or equal to 80 μm has rigidity, which makes it less susceptible to the effect of heat shrinkage of the first adhesive layer and the second adhesive layer in the production of the laminated glass. Consequently, this makes it easier to suppress, for example, the occurrence of orange peel.The thickness of the infrared reflection film 5 is preferably greater than or equal to 85 µm and less than or equal to 115 µm, and more preferably greater than or equal to 90 µm and less than or equal to 110 µm.

[0050] Regarding requirement (2), the infrared reflective film 5 before the laminated glass is manufactured has a heat shrinkage rate of greater than 0.6% and less than 1.2% in a direction in which the heat shrinkage rate becomes maximum (hereinafter referred to as the “maximum shrinkage direction”), and a heat shrinkage rate of greater than 0.6% and less than 1.2% in a direction perpendicular to the maximum direction (hereinafter simply referred to as the “orthogonal direction”).

[0051] However, the heat shrinkage rate of an infrared reflective film is a shrinkage rate of the length in a given direction before and after keeping the infrared reflective film at 150 °C for 30 minutes; specifically, the heat shrinkage rate of an infrared reflective film can be measured as follows.

[0052] First, a strip-shaped test piece is cut out from the infrared reflective film 5 along the maximum shrinkage direction or the orthogonal direction. An infrared reflective film is manufactured by stretching the constituent material into a film shape, as described later; therefore, the stress in the infrared reflective film exists as residual stress. In particular, in the longitudinal direction or the so-called MD direction, which is the flow direction during film production, the residual stress is larger, and the film is prone to heat shrinkage. Therefore, normally, the MD direction corresponds to the maximum shrinkage direction, and the TD direction, as the width direction, corresponds to the orthogonal direction.

[0053] The test specimen has dimensions of, for example, 150 mm in length and 20 mm in width. A pair of reference lines spaced approximately 100 mm apart are drawn on the test specimen in the longitudinal direction, and a length L1 between the reference lines is measured. The test specimen is held vertically in a hot air circulating oven, heated to 150 °C, held for 30 minutes, allowed to cool to room temperature, held for 60 minutes, and then a length L2 between the reference lines is measured. The heat shrinkage rate can then be calculated using the obtained L1 and L2 according to the following formula (iii). Heat shrinkage rate=((L1−L2) / L1)×100[%]

[0054] In an infrared reflective film 5 with a heat shrinkage rate before laminated glass production of more than 0.6% in the maximum shrinkage direction and in the orthogonal direction, the occurrence of orange peel can be suppressed, and with a heat shrinkage rate before laminated glass production of less than 1.2%, the occurrence of deteriorated appearance due to pulling of the adhesive layers can be suppressed. The heat shrinkage rate in the maximum shrinkage direction is preferably greater than or equal to 0.65% and less than or equal to 1.10%, and more preferably greater than or equal to 0.70% and less than or equal to 0.90%. The heat shrinkage rate in the orthogonal direction is preferably greater than or equal to 0.65% and less than or equal to 1.10%, and more preferably greater than or equal to 0.70% and less than or equal to 1.10%.Further, it is preferable that the difference between the heat shrinkage rate in the direction of maximum shrinkage and the heat shrinkage rate in the orthogonal direction is smaller, and it is particularly preferable that the heat shrinkage rates are identical.

[0055] An infrared reflection film 5 that satisfies the requirements (1) and (2), and preferably the requirement of (4), can be manufactured, for example, by the following method. It should be noted that the following example is a method for manufacturing an infrared reflection film 5 made of a laminate using, as two types of resin layers having different refractive indices, a layer A made of a resin A and a layer B made of a resin B. By appropriately changing the method, an infrared reflection film using three or more types of resin layers, or an infrared reflection film having another layer such as a protective layer, can be manufactured.

[0056] An infrared reflective film composed of a laminate using layer A and layer B is manufactured by a process comprising the following steps (a) to (c). In the case where an infrared reflective film satisfying all the requirements of (1) and (2) described above is obtained through step (a) and step (b), step (c) is not performed. In other words, step (c) can be regarded as an optional step. (a) A step of producing an unstretched laminate in which layer A and layer B are alternately laminated, wherein the unstretched laminate has the same number of laminated layers as in a final laminate although the layer thickness is different from the final laminate. (b) A step of stretching the unstretched laminate obtained in step (a) and adjusting the layer thickness to produce a laminate precursor. (c) A step of applying a heat treatment to the laminate precursor after the step (b) to obtain a laminate whose heat shrinkage rate is adjusted to satisfy the requirement of (2). (a) Step of preparing an unstretched laminate

[0057] Resin A and Resin B are prepared in the form of granules or the like. The granules are dried in advance in hot air or vacuum, if necessary, and fed to extruders. In each extruder, the resin is heated to melt above its melting point, extruded at a uniform rate by a gear pump or the like, and foreign substances or a modified resin are removed by a filter or the like.

[0058] Resin A and Resin B, which are discharged from different flow channels using two or more extruders, are then conveyed to a multilayer laminator, formed into a molten laminate laminated to have the desired number of laminated layers by the multilayer laminator, and then molded into a desired shape by a die and discharged. A sheet laminated to have the plurality of layers discharged from the die is extruded onto a heat sink such as a casting drum, cooled, and solidified to obtain an unstretched laminate. It should be noted that a multi-manifold die, a field block, a static mixer, or the like can be used as the multilayer laminator. (b) Stretch step

[0059] The unstretched laminate obtained in step (a) is stretched to produce a laminate precursor. The stretching method is usually biaxial stretching. The biaxial stretching method may be either sequential biaxial stretching or simultaneous biaxial stretching. Further, stretching may be performed again in the MD direction and / or the TD direction. From the viewpoint of suppressing a surface orientation difference and suppressing surface scratches, simultaneous biaxial stretching is preferred. It is preferable to perform the biaxial stretching within a temperature range greater than or equal to a higher glass transition temperature among the glass transition temperatures of Resin A and Resin B and less than or equal to the higher glass transition temperature +120°C.

[0060] The respective stretching factors in the MD direction and the TD direction are adjusted so that each layer has the intended layer thickness in the laminate to be obtained. Furthermore, the stretching factors and the stretching speed are preferably adjusted so that the residual stress in the MD direction becomes equivalent to that in the TD direction. In this way, a laminate precursor is obtained which satisfies the requirement of (1) in the infrared reflective film to be obtained and preferably satisfies the requirement of (4).

[0061] The laminate precursor obtained in the stretching step usually has high residual stress and does not meet the requirement of (2) for the infrared reflective film. Next, by applying the following heat treatment (c), a laminate that meets the requirement of (2) can be obtained. However, in the case where the laminate precursor meets the requirement of (2) as described above, the laminate precursor can be used as the laminate as such. (c) Heat treatment step

[0062] The heat treatment of the laminate precursor is usually performed in a stretching machine. The heat treatment temperature is preferably a temperature lower than a higher melting point among the melting points of Resin A and Resin B, and higher than a lower melting point among the melting points of the resins. Consequently, a resin with the higher melting point maintains a highly oriented state, whereas the orientation is relaxed in a resin with the lower melting point; therefore, a difference between the refractive indices for these resins can be easily provided. Furthermore, the relaxation of the orientation makes it easier to alleviate the stress caused by heat shrinkage. Therefore, the heat shrinkage rate of the laminate can be easily adjusted to fall within the range of (2).

[0063] It should be noted that the heat treatment can be performed such that the relaxation rate during the heat treatment is greater than or equal to 0% and less than or equal to 10%, and preferably greater than or equal to 0% and less than or equal to 5%. The relaxation can be performed in one or both of the TD direction and the MD direction. Further, it is also preferable to perform fine stretching at a rate of greater than or equal to 2% and less than or equal to 10% during the heat treatment. The fine stretching can be performed in one or both of the TD direction and the MD direction. In this way, the heat treatment temperature, heat treatment time, relaxation rate, and fine stretching rate are adjusted so that the thermal shrinkage rate of the laminate is adjusted to within the range of (2).

[0064] It should be noted that for the purpose of adjusting the heat shrinkage rate of the laminate, relaxation may be performed during cooling after the heat treatment step, and further, fine stretching may also be performed after the heat treatment step.

[0065] In the door glass 10, the infrared reflection film 5 is arranged so that its maximum shrinkage direction almost corresponds to the vertical direction or the vehicle width direction of the door glass 10. In this case, "almost corresponds" means that the difference between the angles is within ±5°.

[0066] The requirement of (3) for the infrared reflective film 5 is a requirement for the position of the outer periphery of the infrared reflective film 5 in the visible region of the laminated glass 10 in a front view. Hereinafter, unless otherwise specified, the visible region is a visible region when viewing the laminated glass 10 in a front view. The same applies to the invisible region. When the infrared reflective film 5 meets the requirement of (3), namely, when the distance between the outer periphery of the infrared reflective film 5 and the outer periphery of the laminated glass 10 is within 10 mm in the visible region, the shimmer at the end parts of the laminated glass 10 can be suppressed.

[0067] It should be noted that the outer periphery of the laminated glass 10 in a front view normally corresponds to the outer periphery of the first glass plate 1 and the second glass plate 2 in a front view.

[0068] The distance between the outer periphery of the infrared reflective film 5 and the outer periphery of the laminated glass 10 in the visible range simply needs to be adjusted so that the maximum value is less than or equal to 10 mm. Hereinafter, the distance between the outer periphery of the infrared reflective film 5 and the outer periphery of the laminated glass 10 (the end surface of the glass plate) in the visible range is referred to as "distance W." It should be noted that in the case where the positions of the outer peripheries of the first glass plate and the second glass plate are different, the outer periphery located at outer positions is treated as the outer periphery of the glass plates.For example, as long as the maximum value of the distance W is within 10 mm, the distance W on the left side (front), the right side (back), and the top of the laminated glass 10 above the belt line VL may vary as the visible area, or may vary along each of the sides. In the . Fig. 1, a distance w1 on the left side, a distance w2 on the right side and a distance w3 on the top of the visible area above the belt line VL are set so that they are identical.

[0069] It is assumed that the primary cause of the shimmer is that the end surfaces of the infrared reflective film 5 are visually recognizable. As stated in the Fig. 3, when the window is closed, none of the end surfaces of the door glass 10 is visible; however, in the case where the distance W exceeds 0, depending on the type of vehicle, the outer periphery of the infrared reflection film 5 may be visible in a front view. In this case, depending on the viewing angle, the end surfaces of the infrared reflection film 5 may be visible, particularly on the left side (front side). Furthermore, when the door glass 10 is moved up and down, the end surfaces of the infrared reflection film 5 become easily visible, particularly on the upper side.

[0070] However, in any of the above cases, if the maximum distance W is less than 10 mm, the shimmer at the end portions of the laminated glass can be sufficiently suppressed. The maximum value of the distance W is preferably set to be less than or equal to 5 mm, more preferably less than or equal to 3 mm, even more preferably less than or equal to 1.5 mm, and particularly preferably 0 mm. Further, depending on the type of vehicle, when the window is closed or the door glass 10 is moved up or down, particularly for a side along which the end surface of the infrared reflection film 5 is easily visible, measures such as shortening the distance W may be taken.

[0071] It should be noted that in the laminated glass 10, the infrared reflective film 5 is made of a resin; therefore, even when the distance W is 0 mm, there is almost no effect of exposure to air, and thus durability can be ensured. Furthermore, in the infrared reflective film 5 that meets the requirement of (2), even when the distance W is 0 mm, the deteriorated appearance caused by the pulling of the adhesive layers during the production of the laminated glass hardly occurs.

[0072] In the invisible region of the laminated glass 10, the distance between the outer periphery of the infrared reflective film 5 and the outer periphery of the laminated glass 10 is not particularly limited. However, in view of the manufacturing efficiency of the laminated glass 10, it is preferable that the distance between the outer periphery of the infrared reflective film 5 and the outer periphery of the laminated glass 10 be set to be identical to the distance W in the visible region on the left side (the front side), the right side (the back side), and the bottom side of the laminated glass 10 as the invisible region below the belt line VL. In particular, it is preferable that the distances be set to the distance w1 on the left side and the distance w2 on the right side of the laminated glass 10 in the invisible region, and a distance w4 on the bottom side that is almost equivalent to w1 and w2.

[0073] Regarding the requirement of (5), it is preferable that the infrared reflection film 5 has a minimum radius of curvature of greater than or equal to 8 mm in the visible region of the laminated glass 10. In the visible region of the laminated glass 10, each corner of the outer periphery is normally shaped to have a curvature in plan view. Accordingly, in the visible region of the laminated glass 10, each corner of the outer periphery of the infrared reflection film 5 is shaped to have a curvature in plan view. In the infrared reflection film 5 used in the Fig. 1, a point where the outer periphery has the minimum radius of curvature is a point A at the corner formed by the top and the right side (the back). In a front view, if there is a part along the outer periphery of the infrared reflective sheet 5 where the radius of curvature is less than 8 mm, the design may be affected due to strong reflection of light at the part. The minimum radius of curvature of the outer periphery of the infrared reflective sheet 5 is preferably greater than or equal to 10 mm, and more preferably greater than or equal to 15 mm. [Adhesive layers]

[0074] The first adhesive layer 3 and the second adhesive layer 4 in the door glass 10 have the same shape and dimensions as the main surfaces of the first glass panel 1 and the second glass panel 2, and are flat film-like layers with a thickness described later. The first adhesive layer 3 and the second adhesive layer 4 are interposed between the first glass panel 1 and the second glass panel 2, while interposing the infrared reflection film 5, and have a function of bonding them together, so that they are integrated as the door glass 10.

[0075] The first adhesive layer 3 and the second adhesive layer 4 may have the same structure except for the arrangement positions in the door glass 10. Hereinafter, the first adhesive layer 3 and the second adhesive layer 4 are collectively described as the “adhesive layer(s)”.

[0076] The adhesive layer is formed as an adhesive layer containing a thermoplastic resin used in an adhesive layer of a conventional laminated glass. The type of the thermoplastic resin is not particularly limited and can be appropriately selected from known thermoplastic resins that can form an adhesive layer.

[0077] As the thermoplastic resin, there may be mentioned a polyvinyl acetal such as polyvinyl butyral (PVB), polyvinyl chloride (PVC), saturated polyester, polyurethane, ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer, cycloolefin polymer (COP), and the like. One of the thermoplastic resins can be used alone, or two or more types can be used in combination.

[0078] The thermoplastic resin is selected considering the balance of various properties, including glass transition point, transparency, weather resistance, adhesion, penetration resistance, impact energy absorption, moisture resistance, heat insulation, and the like. The glass transition point of a thermoplastic resin can be adjusted, for example, by the amount of a plasticizer. Considering the balance of the various properties described above, the thermoplastic resin used for the adhesive layer is preferably PVB, EVA, polyurethane, or the like. Furthermore, considering the reduction of deformation of the infrared reflective film 5 during production of the door glass 10, PVB is particularly preferred.

[0079] The adhesive layer contains a thermoplastic resin as the main component. The adhesive layer containing a thermoplastic resin as the main component means that the content of the thermoplastic resin is greater than or equal to 30% by mass based on the total amount of the adhesive layer. The adhesive layer may contain one or more of various additives, including an infrared absorber, an ultraviolet absorber, a fluorescent agent, an adhesion adjuster, a coupling agent, a surfactant, an antioxidant, a heat stabilizer, a light stabilizer, a dehydrating agent, a defoamer, an antistatic agent, a flame retardant, and the like.

[0080] It is preferable that the adhesive layer has a heat shrinkage rate of greater than or equal to 2.0% and less than or equal to 8.0% in the direction in which the heat shrinkage rate becomes maximum (hereinafter referred to as the "maximum shrinkage direction" as in the infrared reflective film), and a heat shrinkage rate of greater than or equal to 2.0% and less than or equal to 8.0% in a direction perpendicular to the maximum direction (hereinafter simply referred to as the "orthogonal direction"). The heat shrinkage rate in the maximum shrinkage direction in the adhesive layer is more preferably greater than or equal to 4.0% and less than or equal to 7.0%, and the heat shrinkage rate in the orthogonal direction is more preferably greater than or equal to 4.0% and less than or equal to 7.0%.

[0081] However, the heat shrinkage rate of the adhesive layer is a shrinkage rate of length in a given direction before and after heat treatment, where "before heat treatment" is defined as the time when the adhesive layer has been left for more than 24 hours in a constant temperature and constant humidity environment at a temperature of 20 °C and a humidity of 55%; and "after heat treatment" is defined as the time when the adhesive layer has been kept at 50 °C for 10 minutes and cooled in a desiccator at 20 °C for 1 hour.Specifically, the heat shrinkage rate of an adhesive layer can be measured in the same manner as in the method of measuring the heat shrinkage rate of an infrared reflective film, except that the temperature and test time of the heat treatment are changed to 50 °C and 10 minutes, and a pre-treatment and a post-treatment are applied before and after the heat treatment.

[0082] According to the infrared reflective film 5, the adhesive layer is formed by stretching the constituent material into a film shape. As a result, in the MD direction, which is the flow direction during manufacturing, the residual stress is greater, and the adhesive layer tends to be more susceptible to heat shrinkage. Therefore, the MD direction normally corresponds to the maximum shrinkage direction, and the TD direction, as the width direction, corresponds to the orthogonal direction. In the case of aligning the maximum shrinkage direction of the infrared reflective film 5 with the maximum shrinkage direction of the adhesive layer when the layers are laminated during manufacturing of the door glass 10, deformation stress tends to be applied to the infrared reflective film 5.

[0083] Therefore, in the door glass 10, the adhesive layer is preferably arranged so that the maximum shrinkage direction of the infrared reflective film 5 is orthogonal to the maximum shrinkage direction of the adhesive layer. Although it is preferable that the adhesive layer and the infrared reflective film be completely orthogonal to each other with respect to the maximum shrinkage directions, it is sufficient that the angle difference from the completely orthogonal state for the adhesive layers is within ±5°.

[0084] Furthermore, in the door glass 10, it is preferable that a value (H) obtained by dividing the heat shrinkage rate in the direction in which the heat shrinkage rate of the infrared reflective film 5 is maximum by an average of the heat shrinkage rates of the first adhesive layer 3 and the second adhesive layer 4 in the respective maximum directions is within a range of greater than or equal to 0.1 and less than or equal to 0.4. In the case where the numerical value H is greater than or equal to 0.1, the deformation stress exerted on the infrared reflective film due to the shrinkage of the adhesive layers is reduced, and a deteriorated appearance of orange peel and / or wrinkles is less likely to occur.In the case where the numerical value H is less than or equal to 0.4, the respective directions of the maximum heat shrinkage rates of the adhesive layers and the infrared reflective film do not come too close to the matching direction; therefore, the shrinkage of the infrared reflective film is not accelerated, and the deteriorated appearance caused by the pulling by the infrared reflective film is less likely to occur.

[0085] The thicknesses of the first adhesive layer 3 and the second adhesive layer 4 are not particularly limited. Specifically, as with an adhesive layer commonly used for laminated glass for vehicles or the like, it is preferable that each of the thicknesses is preferably 0.3 mm to 0.8 mm, and the total thickness of the first adhesive layer 3 and the second adhesive layer 4 is preferably 0.7 mm to 1.5 mm.If the thickness of each of the adhesive layers is less than 0.3 mm or the total thickness of the two layers is less than 0.7 mm, the strength of the two layers may be insufficient; conversely, if the thickness of each adhesive layer exceeds 0.8 mm or the total thickness of the two layers exceeds 1.5 mm, a so-called plate displacement phenomenon may occur, which is a phenomenon in which displacement occurs between the first glass plate 1 and the second glass plate 2, between which the adhesive layers are sandwiched, during a bonding (pressure bonding) step in an autoclave in the manufacture of the door glass 10, which will be described later.

[0086] The adhesive layer is not limited to a single-layer structure. For example, a multi-layer resin film comprising laminated resin films with different properties (with different loss coefficients), which is disclosed in Japanese Unexamined Patent Application Publication No. 2000-272936 and used for the purpose of improving sound insulation performance, can be used as the adhesive layer. Further, in the door glass 10, the adhesive layer can be designed so that the cross-sectional shape in the vertical direction is a wedge shape. As a wedge shape, the thickness of the adhesive layer can be monotonously reduced from the top side to the bottom side, it can be designed to have a part where the thickness is partially uniform as long as the thickness on the top side is greater than the thickness on the bottom side, or the wedge angle can be partially changed. [glass plates]

[0087] Although the thicknesses of the first glass plate 1 and the second glass plate 2 in the door glass 10 vary depending on the composition and the compositions of the first adhesive layer 3 and the second adhesive layer 4, they are generally 0.1 to 10 mm.

[0088] Of the first glass panel 1 and the second glass panel 2, for example, in the case of disposing the first glass panel 1 on the inside of a vehicle, the thickness of the first glass panel 1 is preferably 0.5 to 2.0 mm, and more preferably 0.7 to 1.8 mm. In this case, it is preferable that the thickness of the second glass panel 2 on the outside of the vehicle is greater than or equal to 1.6 mm because then the stone chipping resistance becomes satisfactory. The difference in thickness between the two is preferably 0.3 mm to 1.5 mm, and more preferably 0.5 mm to 1.3 mm. The thickness of the second glass panel 2 on the outside of the vehicle is preferably 1.6 mm to 2.5 mm, and more preferably 1.7 mm to 2.1 mm.

[0089] From the viewpoint of weight reduction, it is preferable that the total plate thickness of the first glass plate 1 and the second glass plate 2 is less than or equal to 4.1 mm, more preferably less than or equal to 3.8 mm, and even more preferably less than or equal to 3.6 mm.

[0090] It should be noted that it is preferable that the end surfaces of the first glass plate 1 and the second glass plate 2 are chamfered as shown in the Fig. 2. Chamfering can be performed using a conventional process. Chamfering the glass panels makes them practical in terms of both design and safety during glass handling.

[0091] The first glass plate 1 and the second glass plate 2 can be formed of an inorganic glass or an organic glass (resin). As the inorganic glass, there can be mentioned a conventional soda-lime glass (also called soda-lime silicate glass), aluminosilicate glass, borosilicate glass, alkali-free glass, quartz glass, and the like. Of these, a soda-lime glass is particularly preferable. As the inorganic glass, for example, a float glass plate formed by a float method or the like can be considered. As the inorganic glass, a tempered glass to which chemical strengthening, thermal strengthening, or the like has been applied can be used.

[0092] As the organic glass (resin), there can be mentioned a polycarbonate resin, polystyrene resin, aromatic polyester resin, acrylic resin, polyester resin, polyarylate resin, polycondensate of a halogenated bisphenol A and ethylene glycol, acrylurethane resin, halogenated aryl group-containing acrylic resin, and the like. Of these, a polycarbonate resin such as an aromatic polycarbonate resin and an acrylic resin such as a polymethyl methacrylate-based acrylic resin are preferable, and a polycarbonate resin is more preferable. Further, among the polycarbonate resins, a bisphenol A-based polycarbonate resin is particularly preferable. It should be noted that two or more types of resins described above can be used together.

[0093] The glass may contain an infrared absorbent, an ultraviolet absorbent, and the like. As such a glass, a green glass, a green UV-absorbing (UV) glass, and the like can be cited. It should be noted that the green UV glass contains more than or equal to 68 mass% and less than or equal to 74 mass% of SiO2; more than or equal to 0.3 mass% and less than or equal to 1.0 mass% of Fe2O3; and more than or equal to 0.05 mass% and less than or equal to 0.5 mass% of FeO, has an ultraviolet transmittance at 350 nm of less than or equal to 1.5%, and has a minimum transmittance value in a range greater than or equal to 550 nm and less than or equal to 1700 nm.

[0094] The glass only needs to be transparent, which can be colorless or colored. Furthermore, the glass can have two or more laminated layers. Although this depends on the application, an inorganic glass is preferred.

[0095] Although the materials of the first glass plate 1 and the second glass plate 2 may be identical or different, it is preferable that they be identical. The shapes of the first glass plate 1 and the second glass plate 2 may be flat or may have a curvature on the entire surface or in part. The surfaces of the first glass plate 1 and the second glass plate 2 exposed to the atmosphere may be coated to impart a water-repellent function, a hydrophilic function, an anti-pollution function, and the like. Furthermore, the outer surfaces of the first glass plate 1 and the second glass plate 2 may normally be provided with a coating comprising a metal layer, such as a low radioactivity coating, an infrared insulating coating, a conductive coating, and the like. [Laminated glass]

[0096] It is preferable that a laminated glass constituting a door glass according to the present invention has a visible light reflectance of greater than or equal to 7% and less than or equal to 10% on the outside of the vehicle.

[0097] If the visible light reflectance (Rv) of the laminated glass 10 measured on the exterior of the vehicle is less than 7%, the infrared reflective film 5 may not function sufficiently, and in particular, the heat insulation performance may be insufficient. If the visible light reflectance (Rv) is greater than 10%, the shimmer caused by the end surfaces of the infrared reflective film will be conspicuous at the end portions of the laminated glass. The visible light reflectance (Rv) is more preferably greater than or equal to 7.5% and less than or equal to 10.0%.

[0098] It is preferable that the laminated glass 10 has a sunlight transmittance (Te) of less than or equal to 45% and a visible light transmittance (Tv) of greater than or equal to 70%. The sunlight transmittance (Te) is more preferably less than or equal to 40%, and particularly preferably less than or equal to 38%. The sunlight reflectance (Re) measured on the outside of the vehicle is more preferably greater than or equal to 18%, and particularly preferably greater than or equal to 20%. The visible light transmittance (Tv) is more preferably greater than or equal to 72%, and particularly preferably greater than or equal to 73%. Furthermore, the haze value of the laminated glass 10 is preferably less than or equal to 1.0%, more preferably less than or equal to 0.8%, and particularly preferably less than or equal to 0.6%.

[0099] It should be noted that the visible light reflectance (Rv) measured on the outside of the vehicle; the sunlight reflectance (Re) measured on the outside of the vehicle; the sunlight transmittance (Te); and the visible light transmittance (Tv) are values obtained by measuring transmittances and reflectances in a wavelength range including at least 300 to 2100 nm by a spectrophotometer or the like and performing calculation using formulas given in JIS R3106 (1998) and JIS R3212 (1998), respectively.In the present specification, unless otherwise stated, visible light reflectance, sunlight reflectance, sunlight transmittance, and visible light refer to visible light reflectance (Rv) measured on the exterior of the vehicle; sunlight reflectance (Re) measured on the exterior of the vehicle; sunlight transmittance (Te); and visible light transmittance (Tv) as measured and calculated by the method described above.

[0100] Further, it is preferable that the hue of reflected light measured by irradiating the laminated glass 10 with light from a D65 light source on the outside of the vehicle at an incident angle of 10 to 60 degrees is -5 < a* < 3 and -12 < b* < 2 according to the CIE 1976 L*a*b* chromaticity coordinates. When the values of a* and b* measured under the above conditions are outside the respective ranges, shimmer at the end portions of the laminated glass caused by the end surfaces of the infrared reflective film tends to be conspicuous. Among them, a* measured under the above conditions is more preferably -3 < a* < 2. Further, b* measured under the above conditions is more preferably -9 < b* < 0. [Making a door pane]

[0101] A door glass according to the present invention can be manufactured according to conventionally known techniques. When manufacturing a door glass (laminated glass) 10, a laminated glass precursor is prepared as the laminated glass before pressure bonding, in which a first glass plate, a first adhesive layer, an infrared reflective film, a second adhesive layer, and a second glass plate prepared in the above-described manner are laminated in this order. At this time, the above-mentioned components are laminated so that the positional relationship between the outer periphery of the laminated glass to be obtained and the outer periphery of the infrared reflective film in a front view satisfies the requirement of (3).Further, if necessary, the TD directions and the MD directions of the first adhesive layer, the infrared reflective film, and the second adhesive layer are set to the above-described preferential direction when the components are laminated.

[0102] The precursor for a laminated glass is placed in a vacuum bag, such as a rubber bag. Then, the vacuum bag is connected to an exhaust system, and a vacuum is applied to the vacuum bag for pressure reduction (degassing), so that the pressure in the vacuum bag is reduced by about -65 to -100 kPa (the absolute pressure is about 36 to 1 kPa), and it is heated to a temperature of about 70 to 110 °C. Thus, a laminated glass is obtained in which all of the first glass plate, the first adhesive layer, the infrared reflection film, the second adhesive layer, and the second glass plate are bonded together. Thereafter, the laminated glass is optionally placed in an autoclave to perform pressure bonding in which heat and pressure are applied under conditions of a temperature of about 120 to 150 °C and a pressure of about 0.98 to 1.47 MPa.Pressure bonding further improves the durability of the laminated glass. [Examples]

[0103] The present invention will be further described below with application examples. It should be noted that the present invention is not limited to the application examples described below. First, nine types of infrared reflection films A to I were manufactured by the following methods. The infrared reflection films A to H are formed from a laminate having two types of laminated resin layers with different refractive indices, each of which has a different heat shrinkage rate. The infrared reflection film I is an infrared reflection film having two types of resin layers with different refractive indices laminated on a PET film. (Production of infrared reflective films A to H)

[0104] Resin A and Resin B were used as two types of thermoplastic resins with different refractive indices. Resin A was PET (crystalline polyester, melting point at 255°C) with an intrinsic viscosity IV = 0.65 and a refractive index of 1.66. Resin B was a PET copolymer (PE / SPG·T / CHDC) with an intrinsic viscosity IV = 0.73 and a refractive index of 1.55, and containing 25 mol% of spiroglycol units and 30 mol% of cyclohexanedicarboxylic acid units based on total units. The two types of prepared resins were melted at 280°C in respective extruders, and 2000 layers were alternately laminated in the thickness direction to have an optical thickness ratio of (Resin A / Resin B) = 1, thereby obtaining an unstretched laminate.

[0105] For each of the infrared reflective films A to H, the unstretched laminate was biaxially stretched by predetermined stretching factors, the thickness of the laminate was adjusted, and then heat treatment was applied to adjust the residual stress (heat shrinkage rate) in the MD direction and the TD direction. Thus, infrared reflective films with the respective physical properties (heat shrinkage rates and thickness) shown in Table 1 were obtained. In the field of "heat shrinkage rates" shown in Table 1, the "maximum direction" corresponds to a direction in which the heat shrinkage rate becomes maximum, specifically, the MD direction of an infrared reflective film. The "orthogonal direction" shown in Table 1 is a direction perpendicular to the "maximum direction," which is the TD direction of the infrared reflective film.It should be noted that the heat shrinkage rate of an infrared reflective film is a shrinkage rate of length in a given direction before and after keeping the infrared reflective film at 150 °C for 30 minutes, and a value was measured by the method described above. (Production of an infrared reflection film I)

[0106] On a PET film with a thickness of 100 µm, Nb2O5 layers as high refractive index dielectric layers and SiO2 layers as low refractive index dielectric layers were alternately laminated in this order with a total of seven layers using a magnetron sputtering method to form an infrared reflection film serving as the infrared reflection film I. [Examples 1 to 14]

[0107] Laminated glasses that have the same laminate structure as the laminated glass used in the Fig. 2, where w1 = w2 in each example and w1 (w2) differs among the examples, were prepared and evaluated as follows. Examples 1 to 8 are application examples, and Examples 9 to 14 are comparative examples. (Manufacture of laminated glasses)

[0108] As the first glass plate, a heat-absorbing green glass (manufactured by Asahi Glass Co., Ltd., commonly known as NHI) with an outer peripheral size of 500 mm in length, 950 mm in width, and a plate thickness of 2 mm was prepared; and as the second glass plate, a clear glass (manufactured by Asahi Glass Co., Ltd., commonly known as FL) with an outer peripheral size of 500 mm in length, 950 mm in width, and a plate thickness of 2 mm was prepared.

[0109] A PVB film with a thickness of 0.76 mm (manufactured by Eastman Chemical Co., product number QL51) was used as the first adhesive layer; a PVB film with a thickness of 0.38 mm (manufactured by Eastman Chemical Co., product number RK11) was used as the second adhesive layer; and the outer peripheral size of each of the adhesive layers had a length of 500 mm and a width of 950 mm, which were the same as those in the first glass plate and the second glass plate. It should be noted that in both of the two types of PVB films with different thicknesses, the heat shrinkage rate in the direction in which the heat shrinkage rate becomes maximum, specifically the heat shrinkage rate in the MD direction, was 6.0%; and the heat shrinkage rate in the orthogonal direction, specifically the heat shrinkage rate in the TD direction, was 5.0%.Furthermore, the heat shrinkage rate of a PVB film is a value of the PVB film measured by the method described above. Further, by adjusting the stretching method, two types of adhesive layers with different heat shrinkage rates were prepared. In both cases, the first adhesive layer was prepared as a PVB film with a thickness of 0.76 mm, and the second adhesive layer was prepared as a PVB film with a thickness of 0.38 mm. One of the adhesive layers had a heat shrinkage rate in the MD direction of 8.5% and a heat shrinkage rate in the TD direction of 7.0%. The other of the adhesive layers had a heat shrinkage rate in the MD direction of 2.5% and a heat shrinkage rate in the TD direction of 2.0%.

[0110] In each of the examples, using one of the infrared reflection films A to I obtained in the manner described above, a laminate having the first glass plate, the first adhesive layer, the infrared reflection film, the second adhesive layer, and the second glass plate laminated in this order was prepared.

[0111] It should be noted that in each of the examples, the size of the infrared reflection films A to I was adjusted so that the distance (w1) between the outer periphery of the infrared reflection films A to I and the outer periphery of the first glass plate and the second glass plate in a front view on all four sides had values as shown in Table 1. Further, all of the first adhesive layer, the infrared reflection film, and the second adhesive layer were laminated so that the MD direction corresponds to the lateral direction of the first glass plate and the second glass plate.

[0112] The laminate was placed in a vacuum bag, which was degassed so that the reading of a pressure gauge became less than or equal to 100 kPa; and then the laminate was heated to 120 °C, pressure-bonded, and further heated and pressurized in an autoclave at 135 °C and 1.3 MPa for 60 minutes; finally, the laminate was cooled to obtain a laminated glass.

[0113] For each laminated glass obtained in each of the examples, the visible light reflectance (Rv); the sunlight reflectance (Re); and a* and b* in the CIE 1976 L*a*b* chromaticity coordinates of reflected light obtained by irradiating the laminated glass with light emitted by a D65 light source from the exterior of the vehicle at an incident angle of 10 degrees were measured. It should be noted that a spectrophotometer (U4100, manufactured by Hitachi High-Technology) was used for the measurement. The results are shown in Table 1. [Evaluation]

[0114] The obtained laminated glass was evaluated for deterioration of the end parts of the infrared reflective film, pulling of the adhesive layers, shimmer, orange peel, and thermal insulation. <Verschlechterung der Endteile der Infrarotreflexionsfolie>

[0115] The laminated glass was placed in a thermo-hygrostat at a temperature of 80°C and a humidity of 95% (relative humidity). After 1000 hours, the presence or absence of discoloration at the end portions of the infrared reflective film was visually inspected. Furthermore, the presence or absence of cracking within an area less than or equal to 20 mm inward from the outer periphery of the infrared reflective film was confirmed by microscopic examination. The evaluation was conducted according to the following criteria.

[0116] A: No discoloration or cracking was observed at the end parts of the infrared reflective film.

[0117] C: Discoloration and cracking were observed at the end parts of the infrared reflective film. <Ziehen von Haftmittelschichten>

[0118] A visual inspection was conducted from a front view to determine whether the outer periphery of the adhesive layers was pulled inward from the outer periphery of the laminated glass, and whether the outer periphery of the infrared reflective film was pulled inward from the corresponding position of the laminate before pressure bonding. The evaluation was conducted according to the following criteria.

[0119] A: No pulling was observed for either the infrared reflective film or the adhesive layers.

[0120] C: A drawn part with a length greater than or equal to 5 mm was observed along the outer periphery of the adhesive layers and the outer periphery of the infrared reflective film.

[0121] A value obtained by dividing the heat shrinkage rate in the direction in which the heat shrinkage rate of the infrared reflection film 5 is maximum by an average of the heat shrinkage rates of the first adhesive layer and the second adhesive layer in the respective maximum directions is calculated as the “heat shrinkage rate (H)”, and the results are summarized in Table 1. <Schimmern; Änderung des Farbtons>

[0122] The laminated glass was assembled into a door pane and brought into a state where it is, for example, attached to a vehicle, as in the Fig. 3 to visually examine the shimmering at the end portions of the door glass (change in color tone) from the inside of the vehicle. The laminated glass was shaped as shown in the Fig. 1. The evaluation was conducted according to the following criteria.

[0123] A: Regardless of whether the door glass was moved upwards or downwards, no change in color tone was observed at the end parts of the door glass.

[0124] B: Only when the door glass was moved up or down (when it was operated), a change in color tone was observed at the end parts of the door glass.

[0125] C: Regardless of whether the door glass was moved upwards or downwards, a change in color tone was observed at the end parts of the door glass. <orangenhaut>

[0126] The laminated glass was placed horizontally in a state where the background was darkened. Furthermore, a fluorescent lamp in the shape of a straight tube (630 mm long, 30 W, FL30SW, manufactured by Mitsubishi Electric Lighting Co., Ltd.) was installed 180 cm above the laminated glass so that the longitudinal direction coincided with the width direction of the laminated glass and turned on. The position of the fluorescent lamp was adjusted so that it was exactly above the center of the laminated glass to visually examine whether the outline of a reflected image of the fluorescent lamp fluctuated in the center. Similarly, the position of the fluorescent lamp was adjusted so that it was exactly above the area around the bottom of the laminated glass to visually examine whether the outline of a reflected image of the fluorescent lamp fluctuated in the area around the bottom. The test results were evaluated according to the following criteria.

[0127] A: No fluctuation was detected in the outline of the reflected image of the fluorescent lamp.

[0128] B: Fluctuation was detected in a part of the outline of the reflected image of the fluorescent lamp at the central part or in the vicinity of the bottom.

[0129] C: Fluctuation was observed in about half of the outline of the reflected image of the fluorescent lamp at the central part or in the vicinity of the bottom. <Wärmeisolierung>

[0130] The sunlight reflectance Re of the laminated glass, measured as above, was used as an indicator of thermal insulation. All sunlight reflectance values were greater than or equal to 20%, indicating good performance. <Gestaltung der Ecken der Türscheibe>

[0131] Laminated glasses with a shape in a front view as shown in the Fig. 1 were manufactured. A total of three types of laminated glasses were manufactured, in which the respective radii of curvature of the infrared reflection film at the point A where the outer periphery has the minimum radius of curvature were 16 mm, 9 mm, and 7 mm, respectively. The infrared reflection film of Example 2 was used for the laminated glasses with the radii of curvature of 16 mm and 9 mm at the point A, and the infrared reflection film of Example 3 was used for the laminated glass with the radius of curvature of 7 mm at the point A. Each of the laminated glasses was placed under a fluorescent lamp, and the appearance of the infrared reflection film at the point A was visually observed. As a result, in the case of the radii of curvature at the point A of 16 mm and 9 mm, no intense reflection of light was observed, and the design was at a problem-free level.On the other hand, in the case where the radius of curvature at point A is 7 mm, intense reflection of light was observed and the design was poor. [Description of symbols] 10 Laminated glass (door glass for vehicles) 1 First glass plate 2 Second glass plate 3 First adhesive layer 4 Second adhesive layer 5 Infrared reflection film 100 automobiles 20 door wall area VL belt line< / orangenhaut>

Claims

[1] Door window for a vehicle, comprising: a laminated glass comprising a first glass plate, a first adhesive layer, an infrared reflective film, a second adhesive layer and a second glass plate laminated in this order, wherein the infrared reflective film comprises a laminate in which 100 or more layers of at least two kinds of resin layers A and B, each made of resins A and B, having different refractive indices are laminated, and the infrared reflective film has a heat shrinkage rate of greater than 0.6% and less than 1.2% in one direction before the laminated glass is manufactured, in which the heat shrinkage rate becomes maximum, and has a heat shrinkage rate of greater than 0.6% and less than 1.2% in a direction perpendicular to the direction in which the heat shrinkage rate becomes maximum, wherein the heat shrinkage rate of the infrared reflective film in a given direction is a shrinkage rate of a length in the given direction before and after holding the infrared reflective film at 150 °C for 30 minutes, wherein the infrared reflection film is obtained by a method comprising (a) a step of producing an unstretched laminate in which layer A and layer B are alternately laminated, the unstretched laminate having the same number of laminated layers as in a final laminate although the layer thickness is different from the final laminate, (b) a step of stretching the unstretched laminate obtained in step (a) and adjusting the layer thickness to produce a laminate precursor, and optionally (c) a step of applying a heat treatment to the laminate precursor after step (b) to obtain a laminate whose heat shrinkage rate is adjusted to satisfy the above heat shrinkage rates, wherein, in an area where the laminated glass is visible when the laminated glass is mounted on the vehicle, an outer periphery of the infrared reflective film is positioned in a front view within a range of up to 10 mm inward from an outer periphery of the laminated glass, wherein each of the first and second glass plates is formed of transparent glass, and wherein, in a region where the laminated glass is visible when the laminated glass is mounted on the vehicle, each corner of an outer periphery of the infrared reflective film in a front view has a curvature, and a minimum radius of curvature of the outer periphery is greater than or equal to 8 mm; and / or wherein the first adhesive layer and the second adhesive layer have a heat shrinkage rate of greater than or equal to 2% and less than or equal to 8% in a direction in which the heat shrinkage rate becomes maximum, and a heat shrinkage rate of greater than or equal to 2% and less than or equal to 8% in a direction perpendicular to the direction in which the heat shrinkage rate becomes maximum, wherein the heat shrinkage rate of the first adhesive layer and the second adhesive layer in a predetermined direction is a shrinkage rate of a length in the predetermined direction before and after holding the first adhesive layer and the second adhesive layer at 50°C for 10 minutes, and wherein the direction in which the heat shrinkage rate of the infrared reflective film becomes maximum is orthogonal to the direction in which the heat shrinkage rate of the first adhesive layer and the second adhesive layer becomes maximum; and / or where a value obtained by dividing the heat shrinkage rate in the direction in which the heat shrinkage rate of the infrared reflective film becomes maximum, obtained by averaging the heat shrinkage rates of the first adhesive layer and the second adhesive layer in respective maximum directions, is within a range of greater than or equal to 0.1 and less than or equal to 0.

4. [2] The door glass for a vehicle according to claim 1, wherein a visible light reflectance of the laminated glass measured on an exterior side of the vehicle is greater than or equal to 7% and less than or equal to 10%. [3] A door glass for a vehicle according to claim 1 or 2, wherein a hue of reflected light obtained by irradiating the laminated glass 10 with light from a D65 light source on an outside of the vehicle at an incident angle of 10 to 60 degrees is -5 < a* < 3 and -12 < b* < 2 according to CIE 1976 L*a*b* chromaticity coordinates. [4] A door glass for a vehicle according to any one of claims 1 to 3, wherein in a region where the laminated glass is visible when the laminated glass is mounted on the vehicle, an outer periphery of the infrared reflective film is arranged to be positioned within a range of up to 5 mm inward from an outer periphery of the laminated glass in a front view. [5] A door glass for a vehicle according to any one of claims 1 to 4, wherein the infrared reflection film has a thickness of less than or equal to 120 µm. [6] The door glass for a vehicle according to any one of claims 1 to 5, wherein the infrared reflection film is formed by alternately laminating two kinds of resin layers having different refractive indices, wherein resins constituting the resin layers comprise at least one kind selected from a polyethylene terephthalate and a polyethylene terephthalate copolymer. [7] A door glass for a vehicle according to any one of claims 1 to 6, wherein the first adhesive layer and the second adhesive layer contain polyvinyl butyral.

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