Composite glass sheet, manufacturing method thereof, and composite protective film laminate

Abstract

To provide a method for manufacturing a composite glass sheet, capable of omitting the bonding and peeling of a cover film.SOLUTION: A method for manufacturing a composite glass sheet comprises the steps of: cutting a glass base material; bonding a first protective film to one surface of the glass base material; and bonding a second protective film to the other surface of the glass base material. At least one of the first and second protective films is a composite protective film including an adhesive layer and a support layer; and the adhesive layer consists of a thermoplastic resin including a polymer having a group including a silicon atom or a thermoplastic resin including an organic silicon compound.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a composite glass sheet, a method for manufacturing the same, and a composite protective film laminate. [Background technology]

[0002] Sheet-shaped glass substrates are sometimes used as protective members for protecting the screens of image display devices. However, because glass substrates are easily broken when used alone, a resin layer such as a protective film is generally provided on the surface of the glass substrate. For example, a technique is known in which a resin film is bonded to the glass substrate via an adhesive layer to reinforce the glass sheet (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-104859 Summary of the Invention [Problem to be solved by the invention]

[0004] Generally, a glass substrate is manufactured in a large area, cut, and stored and transported in a state in which a cover film is attached to the surface for surface protection. When a composite glass sheet including a glass substrate and a resin layer is manufactured using the glass substrate, the cover film is peeled off from the glass substrate, and then the glass substrate is attached to a protective film as a resin layer.

[0005] However, in the conventional method described above, the cover film needs to be attached and peeled off before the composite glass sheet is manufactured, which increases the number of steps and makes the process complicated. Therefore, a method for manufacturing a composite glass sheet that can omit the attachment and peeling of the cover film is desired.

[0006] Furthermore, the manufactured composite glass sheet is required to be able to effectively prevent breakage of the glass substrate contained in the composite glass sheet due to bending, and therefore a protective film for the composite glass sheet is required that can effectively prevent breakage of the glass substrate due to bending.

[0007] The present invention has been devised in view of the above-mentioned problems, and aims to provide a method for manufacturing a composite glass sheet that can omit the bonding and peeling of a cover film, a composite glass sheet that can be manufactured by the manufacturing method, and a composite protective film laminate that can effectively suppress breakage due to bending of the glass substrate. [Means for solving the problem]

[0008] The present inventors have conducted extensive research to solve the above-mentioned problems. As a result, the present inventors have found that an adhesive layer made of a specific thermoplastic resin can function as both a cover film and a protective film. The present inventors have also found that when the adhesive layer is attached to a glass substrate instead of a cover film, there is no need to prepare a cover film separately from the protective film, and therefore the attachment and peeling of the cover film can be omitted. Furthermore, the present inventors have found that when the adhesive layer is attached to a glass substrate, breakage of the glass substrate due to bending can be effectively suppressed. Based on these findings, the present inventors have completed the present invention. That is, the present invention includes the following.

[0009] [1] A step of cutting a glass substrate; a step of laminating a first protective film on one surface of the glass substrate; and bonding a second protective film to the other surface of the glass substrate, At least one of the first protective film and the second protective film is a composite protective film including an adhesive layer and a support layer, A method for producing a composite glass sheet, wherein the adhesive layer is made of a thermoplastic resin containing a polymer having a group containing a silicon atom, or a thermoplastic resin containing an organosilicon compound. [2] The method for producing a composite glass sheet according to [1], wherein the adhesive layer has a thickness of less than 10 μm. [3] The method for producing a composite glass sheet according to [1] or [2], wherein the composite protective film comprises a flexible layer between the adhesive layer and the support layer, the flexible layer having a storage modulus smaller than that of the adhesive layer. [4] The method for producing a composite glass sheet according to any one of [1] to [3], wherein the support layer is a release film. [5] The method for manufacturing a composite glass sheet according to any one of [1] to [4], wherein no solid comes into contact with the surface of the glass substrate between the step of cutting the glass substrate and the step of bonding the surface of the glass substrate and the composite protective film. [6] A composite glass sheet comprising a glass substrate, a first protective film provided on one surface of the glass substrate, and a second protective film provided on the other surface of the glass substrate, At least one of the first protective film and the second protective film is a composite protective film including an adhesive layer and a support layer, A composite glass sheet, wherein the adhesive layer is made of a thermoplastic resin containing a polymer having a group containing a silicon atom, or a thermoplastic resin containing an organosilicon compound. [7] The composite glass sheet according to [6], wherein the adhesive layer has a thickness of less than 10 μm. [8] The composite glass sheet according to [6] or [7], further comprising a flexible layer between the adhesive layer and the support layer, the flexible layer having a storage modulus smaller than that of the adhesive layer. [9] The composite glass sheet according to any one of [6] to [8], wherein the support layer is a release film.

[10] A composite protective film laminate comprising a release film, an adhesive layer, a flexible layer, and a support layer in this order, the adhesive layer is made of a thermoplastic resin containing a polymer having a group containing a silicon atom, or a thermoplastic resin containing an organosilicon compound, A composite protective film laminate, wherein the compliant layer has a lower storage modulus than the adhesive layer. [Effects of the Invention]

[0010] The present invention provides a method for manufacturing a composite glass sheet that eliminates the need to attach and peel a cover film, a composite glass sheet that can be manufactured by the manufacturing method, and a composite protective film laminate that can effectively suppress breakage of the glass substrate due to bending. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional view schematically showing a composite protective film according to one embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view schematically showing a release film laminate according to one embodiment of the present invention. [Figure 3] FIG. 3 is a side view that schematically shows how the glass substrate is cut in the method for producing a composite glass sheet according to one embodiment of the present invention. [Figure 4] FIG. 4 is a side view that schematically shows how the first protective film and the second protective film are bonded to the glass substrate in the method for producing a composite glass sheet according to one embodiment of the present invention. [Figure 5] FIG. 5 is a cross-sectional view schematically showing a composite glass sheet produced by a production method according to one embodiment of the present invention. [Figure 6] FIG. 6 is a cross-sectional view showing a schematic diagram of a composite glass sheet in use according to one embodiment of the present invention. [Figure 7] FIG. 7 is a cross-sectional view showing a schematic diagram of a composite glass sheet in use according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will be described in detail below with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples shown below, and can be implemented with any modifications within the scope of the claims of the present invention and their equivalents.

[0013] In the following description, unless otherwise specified, "(meth)acrylic" is a term that includes "acrylic," "methacrylic," and combinations thereof. For example, "(meth)acrylic acid alkyl ester" includes acrylic acid alkyl ester, methacrylic acid alkyl ester, or a mixture thereof.

[0014] In the following description, the term "solvent" is used in a broad sense for convenience, and includes not only a solution medium but also a dispersion medium, and also includes a medium containing both dissolved and dispersed substances in such a medium.

[0015] [1. Overview of composite glass sheet manufacturing method] A method for producing a composite glass sheet according to one embodiment of the present invention includes the steps of cutting a glass substrate, bonding a first protective film to one surface of the glass substrate, and bonding a second protective film to the other surface of the glass substrate. Either the step of bonding the glass substrate and the first protective film or the step of bonding the glass substrate and the second protective film may be performed first, or both steps may be performed simultaneously.

[0016] In this manufacturing method, a composite protective film including an adhesive layer and a support layer is used as at least one of the first protective film and the second protective film. Therefore, this manufacturing method can manufacture a composite glass sheet including a glass substrate and an adhesive layer. Usually, this manufacturing method produces a composite glass sheet including a glass substrate, an adhesive layer, and a support layer in this order, but when the manufacturing method includes a step of peeling off the support layer, it can produce a composite glass sheet including a glass substrate and an adhesive layer but not a support layer.

[0017] Usually, when a composite glass sheet is used, the support layer is peeled off from the composite glass sheet. For example, when a composite glass sheet is used as a protective member for the screen of an image display device, the support layer is peeled off. However, the adhesive layer usually remains on the surface of the glass substrate even when the composite glass sheet is used. Therefore, a sheet comprising a glass substrate and an adhesive layer can be used as a protective member.

[0018] In this embodiment, the adhesive layer is made of a thermoplastic resin containing a polymer having a silicon atom-containing group, or a thermoplastic resin containing an organosilicon compound. In the following description, the "silicon atom-containing group" may be referred to as an "Si-containing group" as appropriate. Furthermore, the polymer having a silicon atom-containing group may be referred to as an "Si polymer" as appropriate.

[0019] An adhesive layer made of a thermoplastic resin containing a Si polymer or a thermoplastic resin containing an organosilicon compound can have high adhesive strength to a glass substrate. Furthermore, by combining this adhesive layer with a glass substrate, the glass substrate's resistance to bending can be improved. Therefore, in this embodiment, the adhesive layer can function as a cover film that protects the surface of the cut glass substrate and also as a protective film that suppresses breakage of the glass substrate due to bending. Therefore, since there is no need to separately prepare a cover glass and a protective film, the manufacturing method according to this embodiment can manufacture a composite glass sheet without laminating and peeling off the cover film.

[0020] The composite protective film preferably has a flexible layer between the adhesive layer and the support layer, the flexible layer having a storage modulus smaller than that of the adhesive layer. This flexible layer is usually not peeled off even when the composite glass sheet is used. Therefore, when the flexible layer is provided, a composite protective film can be obtained that has the glass substrate, the adhesive layer, and the flexible layer in this order in the thickness direction.

[0021] [2. Composite protective film] Fig. 1 is a cross-sectional view schematically showing a composite protective film 100 according to one embodiment of the present invention. As shown in Fig. 1, the composite protective film 100 according to one embodiment of the present invention includes a support layer 110 and an adhesive layer 120. Furthermore, the composite protective film 100 preferably includes a flexible layer 130 between the support layer 110 and the adhesive layer 120.

[0022] [2.1. Adhesive layer] The adhesive layer is made of a thermoplastic resin containing a Si polymer having a Si-containing group, or a thermoplastic resin containing an organosilicon compound. Therefore, the adhesive layer contains a thermoplastic resin containing a Si polymer, or a thermoplastic resin containing an organosilicon compound. Furthermore, the adhesive layer preferably contains only a thermoplastic resin containing a Si polymer, or a thermoplastic resin containing an organosilicon compound. The thermoplastic resin contained in the adhesive layer may contain a combination of a Si polymer and an organosilicon compound. The adhesive layer can be bonded to a glass substrate with high adhesive strength. This adhesive layer can protect the surface of the glass substrate and prevent breakage of the glass substrate due to bending.

[0023] (2.1.1. Composition of Thermoplastic Resin Containing Si Polymer Having Si-Containing Group) The Si-containing group of the Si polymer represents a group containing a silicon atom. This Si-containing group can usually be a polar group having polarity. Therefore, the polarity of the Si-containing group allows the Si polymer and glass to have high affinity. Therefore, an adhesive layer containing the Si polymer can be bonded to a glass substrate with high adhesive strength.

[0024] The Si-containing group is preferably an alkoxysilyl group. The alkoxysilyl group can react with hydroxyl groups generally present on the surface of a glass substrate to form a bond. Therefore, the bond can effectively increase the adhesive strength between the glass substrate and the adhesive layer.

[0025] Examples of the alkoxysilyl group include a trialkoxysilyl group, an alkyldialkoxysilyl group, and an aryldialkoxysilyl group. The number of carbon atoms in the trialkoxysilyl group is preferably 3 to 9. Examples of the trialkoxysilyl group include a trimethoxysilyl group and a triethoxysilyl group. The number of carbon atoms in the alkyldialkoxysilyl group is preferably 3 to 20. Examples of the alkyldialkoxysilyl group include a methyldimethoxysilyl group, a methyldiethoxysilyl group, an ethyldimethoxysilyl group, an ethyldiethoxysilyl group, a propyldimethoxysilyl group, and a propyldiethoxysilyl group. The number of carbon atoms in the aryldialkoxysilyl group is preferably 8 to 16. Examples of the aryldialkoxysilyl group include a phenyldimethoxysilyl group and a phenyldiethoxysilyl group. Among these, a trimethoxysilyl group is preferred from the viewpoint of effectively increasing the adhesive strength between the glass substrate and the adhesive layer. The number of types of Si-containing groups may be one or more.

[0026] The Si polymer may have a structure in which an Si-containing group has been introduced into a polymer before the Si-containing group has been introduced. The polymer before the Si-containing group has been introduced usually does not contain an Si-containing group. In the following description, the polymer before the Si-containing group has been introduced may be referred to as a "pre-reaction polymer" to distinguish it from the Si polymer. For example, a Si polymer having an alkoxysilyl group as the Si-containing group may have a structure in which an alkoxysilyl group has been introduced into a pre-reaction polymer.

[0027] The Si polymer may be a graft polymer having an Si-containing group. Examples of graft polymers having an Si-containing group include graft polymers containing a structural unit containing an Si-containing group. The structural unit containing an Si-containing group refers to a unit having a structure obtained by polymerizing a monomer having an Si-containing group. The graft polymer containing a structural unit containing an Si-containing group may be a polymer having a structure obtained by graft polymerization of a certain pre-reaction polymer with a monomer having an Si-containing group. However, the graft polymer is not limited by its production method.

[0028] Examples of pre-reaction polymers include ethylene-α-olefin copolymers such as ethylene-propylene copolymer; ethylene-α-olefin-polyene copolymers; copolymers of ethylene and unsaturated carboxylic acid esters such as ethylene-methyl methacrylate and ethylene-butyl acrylate; copolymers of ethylene and fatty acid vinyl such as ethylene-vinyl acetate; polymers of alkyl acrylates such as ethyl acrylate, butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, and lauryl acrylate; diene copolymers such as polybutadiene, polyisoprene, acrylonitrile-butadiene copolymer, butadiene-isoprene copolymer, butadiene-(meth)acrylic acid alkyl ester copolymer, butadiene-(meth)acrylic acid alkyl ester-acrylonitrile copolymer, and butadiene-(meth)acrylic acid alkyl ester-acrylonitrile-styrene copolymer; butylene Examples of the prepolymer include styrene-isoprene copolymers; aromatic vinyl compound-conjugated diene copolymers such as styrene-butadiene random copolymers, styrene-isoprene random copolymers, styrene-butadiene block copolymers, styrene-butadiene-styrene block copolymers, styrene-isoprene block copolymers, and styrene-isoprene-styrene block copolymers; hydrogenated aromatic vinyl compound-conjugated diene copolymers such as hydrogenated styrene-butadiene random copolymers, hydrogenated styrene-isoprene random copolymers, hydrogenated styrene-butadiene block copolymers, hydrogenated styrene-butadiene-styrene block copolymers, hydrogenated styrene-isoprene block copolymers, and hydrogenated styrene-isoprene-styrene block copolymers; and low-crystalline polybutadiene, styrene-grafted ethylene-propylene elastomers, thermoplastic polyester elastomers, and ethylene-based ionomers. The prepolymers may be used singly or in combination of two or more.

[0029] Among these, the pre-reaction polymer is preferably a polymer selected from an aromatic vinyl compound-conjugated diene copolymer, a hydrogenated aromatic vinyl compound-conjugated diene copolymer, and a combination thereof. Therefore, the Si polymer preferably has a structure in which an Si-containing group is introduced into a polymer selected from an aromatic vinyl compound-conjugated diene copolymer, a hydrogenated aromatic vinyl compound-conjugated diene copolymer, and a combination thereof.

[0030] The aromatic vinyl compound-conjugated diene copolymer is preferably an aromatic vinyl compound-conjugated diene block copolymer, which is preferably selected from a styrene-butadiene block copolymer, a styrene-butadiene-styrene block copolymer, a styrene-isoprene block copolymer, a styrene-isoprene-styrene block copolymer, and a mixture thereof.

[0031] The hydrogenated aromatic vinyl compound-conjugated diene copolymer refers to a hydrogenated product of an aromatic vinyl compound-conjugated diene copolymer. That is, the hydrogenated aromatic vinyl compound-conjugated diene copolymer has a structure obtained by hydrogenating a part or all of the carbon-carbon unsaturated bonds in the main chain and side chain of the aromatic vinyl compound-conjugated diene copolymer, the carbon-carbon bonds in the aromatic ring, or both. However, the copolymer and the hydrogenated product are not limited by their production methods.

[0032] The hydrogenation rate of the hydrogenated aromatic vinyl compound-conjugated diene copolymer is usually 90% or more, preferably 97% or more, and more preferably 99% or more. The higher the hydrogenation rate, the better the heat resistance and light resistance of the resin. Here, the hydrogenation rate of the hydrogenated product is 1 It can be determined by measurement using H-NMR.

[0033] The hydrogenation rate of the carbon-carbon unsaturated bonds in the main chain and side chain of the hydrogenated aromatic vinyl compound-conjugated diene copolymer is preferably 95% or more, more preferably 99% or more. By increasing the hydrogenation rate of the carbon-carbon unsaturated bonds in the main chain and side chain of the hydrogenated aromatic vinyl compound-conjugated diene copolymer, the light resistance and oxidation resistance of the resin can be further improved.

[0034] The hydrogenation rate of the carbon-carbon unsaturated bonds in the aromatic ring of the hydrogenated aromatic vinyl compound-conjugated diene copolymer is preferably 90% or higher, more preferably 93% or higher, and particularly preferably 95% or higher. Increasing the hydrogenation rate of the carbon-carbon unsaturated bonds in the aromatic ring increases the glass transition temperature of the hydrogenated product, effectively improving the heat resistance of the resin. Furthermore, the photoelastic coefficient of the resin can be reduced, thereby reducing the occurrence of retardation in the adhesive layer.

[0035] The hydrogenated aromatic vinyl compound-conjugated diene copolymer is preferably a hydrogenated aromatic vinyl compound-conjugated diene block copolymer. The hydrogenated aromatic vinyl compound-conjugated diene block copolymer is preferably selected from hydrogenated styrene-butadiene block copolymers, hydrogenated styrene-butadiene-styrene block copolymers, hydrogenated styrene-isoprene block copolymers, hydrogenated styrene-isoprene-styrene block copolymers, and mixtures thereof. Specific examples of these copolymers include those described in technical documents such as JP-A-2-133406, JP-A-2-305814, JP-A-3-72512, JP-A-3-74409, and WO 2015 / 099079.

[0036] The hydrogenated aromatic vinyl compound-conjugated diene block copolymer is preferably one having a structure in which both the unsaturated bond and the aromatic ring of the conjugated diene are hydrogenated.

[0037] Particularly preferred block forms of the hydrogenated aromatic vinyl compound-conjugated diene block copolymer are a triblock copolymer in which a block [A] of a hydrogenated aromatic vinyl polymer is bonded to both ends of a block [B] of a hydrogenated conjugated diene polymer, or a pentablock copolymer in which a polymer block [B] is bonded to both ends of a polymer block [A] and a polymer block [A] is bonded to the other end of each of the polymer blocks [B]. In particular, an [A]-[B]-[A] triblock copolymer is particularly preferred because it is easy to produce and the physical properties of the block copolymer can be controlled within preferred ranges.

[0038] In the hydrogenated aromatic vinyl compound-conjugated diene block copolymer, the ratio (wA / wB) of the weight fraction (wA) of all polymer blocks [A] in the entire block copolymer to the weight fraction (wB) of all polymer blocks [B] in the entire block copolymer is usually 20 / 80 or more, preferably 30 / 70 or more, and usually 60 / 40 or less, preferably 55 / 45 or less. When the ratio (wA / wB) is equal to or greater than the lower limit of the above range, the heat resistance of the resin can be improved. When the ratio (wA / wB) is equal to or less than the upper limit, the flexibility of the resin can be increased. Furthermore, when the ratio (wA / wB) is within the above range, breakage of the glass substrate due to bending can be particularly effectively suppressed.

[0039] By reacting the pre-reaction polymer with a compound having a Si-containing group, the Si-containing group can be introduced into the pre-reaction polymer to obtain a Si polymer. Specifically, by reacting the pre-reaction polymer with a monomer having a Si-containing group, a graft polymer having a Si-containing group can be obtained. Examples of compounds having an Si-containing group that can be used as a monomer include ethylenically unsaturated silane compounds having an alkoxysilyl group, such as vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, dimethoxymethylvinylsilane, diethoxymethylvinylsilane, p-styryltrimethoxysilane, p-styryltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-acryloxypropyltriethoxysilane, and 2-norbornene-5-yltrimethoxysilane. The compounds having an Si-containing group may be used alone or in combination of two or more.

[0040] When introducing alkoxysilyl groups, the amount of alkoxysilyl groups introduced is usually 0.1 parts by weight or more, preferably 0.2 parts by weight or more, more preferably 0.3 parts by weight or more, and usually 10 parts by weight or less, preferably 5 parts by weight or less, more preferably 3 parts by weight or less, relative to 100 parts by weight of the pre-reaction polymer. When the amount of alkoxysilyl groups introduced is within the above range, the degree of crosslinking between alkoxysilyl groups decomposed by moisture can be prevented from becoming excessively high, so high adhesiveness can be maintained. Examples of methods for introducing alkoxysilyl groups include those described in International Publication No. 2015 / 099079. In addition, the amount of Si-containing groups is 1 It can be measured by H-NMR spectroscopy. When measuring the amount of Si-containing groups, if the amount of Si-containing groups is small, the number of integrations can be increased.

[0041] As described above, introducing alkoxysilyl groups into a pre-reaction polymer is called silane modification. During silane modification, the alkoxysilyl groups may be bonded directly to the pre-reaction polymer, or may be bonded via a divalent organic group such as an alkylene group. Hereinafter, a polymer obtained by silane modification of a pre-reaction polymer may also be referred to as a "silane-modified polymer." Preferred silane-modified polymers are one or more polymers selected from a silane-modified hydrogenated styrene-butadiene block copolymer, a silane-modified hydrogenated styrene-butadiene-styrene block copolymer, a silane-modified hydrogenated styrene-isoprene block copolymer, and a silane-modified hydrogenated styrene-isoprene-styrene block copolymer.

[0042] The weight-average molecular weight (Mw) of the Si polymer is preferably 20,000 or more, more preferably 30,000 or more, particularly preferably 35,000 or more, and preferably 200,000 or less, more preferably 100,000 or less, particularly preferably 70,000 or less. The molecular weight distribution (Mw / Mn) of the Si polymer is preferably 4 or less, more preferably 3 or less, particularly preferably 2 or less, and preferably 1 or more. Here, Mn represents the number-average molecular weight. When the weight-average molecular weight Mw and molecular weight distribution Mw / Mn of the Si polymer are within the above ranges, the mechanical strength and heat resistance of the resin can be improved. The weight-average molecular weight of the polymer can be measured in polystyrene equivalent terms by gel permeation chromatography using tetrahydrofuran as a solvent.

[0043] The glass transition temperature Tg of the Si polymer is not particularly limited, but is preferably 40° C. or higher, more preferably 70° C. or higher, and is preferably 200° C. or lower, more preferably 180° C. or lower, and even more preferably 160° C. or lower. The glass transition temperature can be measured from the peak of the loss tangent tanδ (loss modulus / storage modulus) measured using a dynamic viscoelasticity measuring device.

[0044] The amount of Si polymer contained in the thermoplastic resin is preferably 30% by weight or more, more preferably 50% by weight or more, and particularly preferably 65% ​​by weight or more, relative to 100% by weight of the thermoplastic resin, and is usually 100% by weight or less, preferably 95% by weight or less, more preferably 90% by weight or less, and particularly preferably 85% by weight or less.

[0045] The thermoplastic resin containing the Si polymer may contain an optional component in combination with the Si polymer. The thermoplastic resin may contain, for example, a softener as an optional component. The softener can reduce the storage modulus of the thermoplastic resin.

[0046] The softener may be a compound that is liquid under normal temperature and pressure conditions. A compound that is compatible with the Si polymer is preferred. Suitable examples of the softener include hydrocarbon-based monomers and oligomers; organic acid ester-based softeners such as monobasic organic acid esters and polybasic organic acid esters; and phosphate-based softeners such as organic phosphates and organic phosphites. One type of softener may be used alone, or two or more types may be used in combination. Among these, hydrocarbon-based monomers and oligomers are preferred.

[0047] Specific examples of hydrocarbon monomers and oligomers include polyisobutylene, polybutene, poly-4-methylpentene, liquid paraffin, poly-1-octene, ethylene-α-olefin copolymers, polyisoprene, alicyclic hydrocarbons, other aliphatic hydrocarbons, aromatic vinyl compound-conjugated diene copolymers, hydrogenated products of the above compounds, and hydrogenated indene-styrene copolymers. Among these, polyisobutylene, polybutene, hydrogenated polyisobutylene, and hydrogenated polybutene are preferred. Many of these hydrocarbon monomers and oligomers are highly compatible with Si polymers.

[0048] The hydrocarbon monomers and oligomers are preferably polymers of hydrocarbon compounds having a molecular weight within a specific range, since they disperse well in the components that make up the adhesive layer without significantly impairing heat resistance. The number-average molecular weight of the hydrocarbon oligomer is preferably 200 to 5,000, more preferably 300 to 3,000, and even more preferably 500 to 2,000. For example, polybutene having a number-average molecular weight within the above range can be uniformly mixed with a polymer having an alkoxysilyl group in any ratio.

[0049] The amount of the softener is preferably 5 parts by weight or more, more preferably 10 parts by weight or more, particularly preferably 15 parts by weight or more, and preferably 70 parts by weight or less, more preferably 60 parts by weight or less, particularly preferably 50 parts by weight or less, relative to 100 parts by weight of the Si polymer.

[0050] The thermoplastic resin containing a Si polymer may contain, for example, an antioxidant as an optional component. Examples of the antioxidant include phosphorus-based antioxidants, phenol-based antioxidants, and sulfur-based antioxidants, and phosphorus-based antioxidants are preferred because they cause less coloring.

[0051] Examples of phosphorus-based antioxidants include monophosphite compounds such as triphenyl phosphite, diphenyl isodecyl phosphite, phenyl diisodecyl phosphite, tris(nonylphenyl) phosphite, tris(dinonylphenyl) phosphite, tris(2,4-di-t-butylphenyl) phosphite, and 10-(3,5-di-t-butyl-4-hydroxybenzyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide; 4,4'-butylidene-bis(3-methyl-6-t-butylphenyl-di-tridecyl phosphite); diphosphite compounds such as 4,4'-isopropylidene-bis(phenyl-di-alkyl(C12-C15)phosphite); 6-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propoxy]-2,4,8,10-tetrakis-t-butyldibenzo[d,f][1.3.2]dioxaphosphepine; and 6-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propoxy]-2,4,8,10-tetrakis-t-butyldibenzo[d,f][1.3.2]dioxaphosphepine. The antioxidants may be used singly or in combination of two or more.

[0052] The amount of the antioxidant is preferably 0.01 part by weight or more, more preferably 0.05 part by weight or more, particularly preferably 0.1 part by weight or more, and preferably 1 part by weight or less, more preferably 0.5 part by weight or less, particularly preferably 0.3 part by weight or less, relative to 100 parts by weight of the Si polymer.

[0053] Examples of other optional components include light stabilizers, ultraviolet absorbers, antioxidants, lubricants, inorganic fillers, and organosilicon compounds described below. The optional components may be used alone or in combination of two or more at any ratio.

[0054] (2.1.2. Composition of Thermoplastic Resin Containing Organosilicon Compound) Thermoplastic resins containing organosilicon compounds usually contain a combination of a polymer and an organosilicon compound. Examples of the polymer include acrylic polymers, urethane polymers, polyester polymers, rubber polymers, and epoxy polymers. Furthermore, the polymer may be, for example, the above-mentioned Si polymer, or a pre-reaction polymer thereof. One type of polymer may be used alone, or two or more types may be used in combination.

[0055] The weight-average molecular weight (Mw) of the polymer contained in the thermoplastic resin containing an organosilicon compound is not particularly limited, but is preferably in the same range as the weight-average molecular weight (Mw) of the Si polymer. Furthermore, the molecular weight distribution (Mw / Mn) of the polymer contained in the thermoplastic resin containing an organosilicon compound is preferably in the same range as the molecular weight distribution (Mw / Mn) of the Si polymer. Furthermore, the glass transition temperature of the polymer contained in the thermoplastic resin containing an organosilicon compound is preferably in the same range as the glass transition temperature of the Si polymer.

[0056] The amount of polymer contained in the thermoplastic resin containing an organosilicon compound is preferably in the same range as the amount of Si polymer contained in the thermoplastic resin containing an Si polymer.

[0057] The organosilicon compound contains a combination of an organic group and a silicon atom. The organic group of the organosilicon compound can exhibit high affinity to organic components such as polymers contained in thermoplastic resins. Furthermore, the silicon atom contained in the organosilicon compound can exhibit high affinity to glass substrates. Therefore, an adhesive layer containing the organosilicon compound can be bonded to a glass substrate with high adhesive strength.

[0058] As the organosilicon compound, a silane coupling agent is preferred. The silane coupling agent can particularly effectively increase the adhesive strength between the glass substrate and the adhesive layer. Examples of the silane coupling agent include vinyltrimethoxysilane, vinyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, N-2-(aminoethyl)-2-(methylpropyl ... N-(1,3-dimethyl-butylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, bis(triethoxysilylpropyl)tetrasulfide, and 3-isocyanatopropyltriethoxysilane.

[0059] The organosilicon compounds may be used singly or in combination of two or more.

[0060] The amount of the organosilicon compound is preferably 0.01 part by weight or more, more preferably 0.03 part by weight or more, and particularly preferably 0.05 part by weight or more, per 100 parts by weight of the polymer, and is preferably 10 parts by weight or less, more preferably 5 parts by weight or less, and particularly preferably 3 parts by weight or less.

[0061] The thermoplastic resin containing an organosilicon compound may contain an optional component in combination with the polymer and the organosilicon compound. The thermoplastic resin may contain, for example, a softener as an optional component. The softener can reduce the storage modulus of the thermoplastic resin. For example, the softeners mentioned in the description of the thermoplastic resin containing a Si polymer can be used. Furthermore, the amount of softener per 100 parts by weight of the polymer in the thermoplastic resin containing an organosilicon compound may be in the same range as the amount of softener per 100 parts by weight of the Si polymer in the thermoplastic resin containing a Si polymer.

[0062] The thermoplastic resin containing an organosilicon compound may contain, for example, an antioxidant as an optional component. Examples of antioxidants that can be used include those listed in the description of the thermoplastic resin containing a Si polymer. The amount of antioxidant per 100 parts by weight of the polymer in the thermoplastic resin containing an organosilicon compound may be the same as the amount of antioxidant per 100 parts by weight of the Si polymer in the thermoplastic resin containing a Si polymer.

[0063] Examples of other optional components include the same as the optional components of the thermoplastic resin containing a Si polymer.

[0064] (2.1.3. Physical properties of thermoplastic resins) The thermoplastic resin contained in the adhesive layer may be a thermoplastic elastomer. A thermoplastic elastomer is a material that exhibits rubber properties at room temperature but plasticizes at high temperatures, making it suitable for molding. Such thermoplastic elastomers are resistant to elongation and breakage under small loads. Specifically, at 23°C, thermoplastic elastomers may exhibit a Young's modulus of 0.001 GPa to 1 GPa and a tensile elongation (elongation at break) of 100% to 1000%. Thermoplastic elastomers may also exhibit a sharp decrease in storage modulus and a peak in the loss tangent tanδ (loss modulus / storage modulus) or a value exceeding 1, indicating softening, in the high temperature range of 40°C to 200°C. Young's modulus and tensile elongation can be measured according to JIS K7113. Loss tangent tanδ can be measured using a commercially available dynamic viscoelasticity measuring device.

[0065] (2.1.4. Characteristics of the adhesive layer) The adhesive layer preferably has a storage modulus within a specific range. The specific storage modulus of the adhesive layer is preferably 10 MPa or more, more preferably 50 MPa or more, particularly preferably 100 MPa or more, and preferably 5000 MPa or less, more preferably 3000 MPa or less, particularly preferably 1000 MPa or less. When the adhesive layer has a storage modulus within the above range, breakage of the glass substrate due to bending can be effectively suppressed.

[0066] The storage modulus of the adhesive layer can be measured at a measurement temperature of 25° C. using a dynamic viscoelasticity measuring device at a frequency of 1 Hz.

[0067] The storage modulus of the adhesive layer can be adjusted, for example, by adjusting the types and proportions of components contained in the thermoplastic resin. In particular, the storage modulus can be easily adjusted by adjusting the proportion of the softener contained in the thermoplastic resin.

[0068] The thickness of the adhesive layer is preferably 0.1 μm or more, more preferably 0.5 μm or more, and particularly preferably 2 μm or more from the viewpoint of effectively protecting the surface of the glass substrate, and is preferably less than 10 μm, more preferably less than 8 μm, and particularly preferably less than 6 μm from the viewpoint of effectively suppressing breakage of the glass substrate due to bending.

[0069] (2.1.5. Method for forming adhesive layer) There are no particular limitations on the method for forming the adhesive layer. For example, the adhesive layer can be formed by a method including the steps of preparing a resin liquid containing a thermoplastic resin and a solvent, applying the resin liquid to an appropriate support surface to form a resin liquid film, and drying the film.

[0070] As the solvent, an organic solvent can be used. Examples of the organic solvent include alcohol solvents, ether solvents, ester solvents, ketone solvents, and hydrocarbon solvents, with hydrocarbon solvents being preferred. Examples of the hydrocarbon solvent include aliphatic hydrocarbon solvents such as hexane, n-octane, n-decane, dodecane, tridecane, and tetradecane; alicyclic hydrocarbon solvents such as cyclohexane, methylcyclohexane, ethylcyclohexane, cyclooctane, cyclodecane, and cyclododecane; and aromatic hydrocarbon solvents such as toluene, benzene, xylene, decahydronaphthalene, and trimethylbenzene. Furthermore, the solvent may be used alone or in combination of two or more.

[0071] There are no particular limitations on the concentration of the thermoplastic resin in the resin liquid, but it is preferably 2% by weight or more, more preferably 3% by weight or more, and particularly preferably 5% by weight or more, and preferably 40% by weight or less, more preferably 35% by weight or less, and particularly preferably 30% by weight or less.

[0072] The support surface to which the resin liquid is applied may be, for example, the surface of a support layer. Alternatively, the surface of an appropriate member such as a film, sheet, or substrate may be used as the support surface. Typically, a smooth, flat surface of a member that is insoluble in the solvent contained in the resin liquid can be used as the support surface.

[0073] There are no particular limitations on the method for applying the resin liquid. Examples of the application method include a doctor blade method, a silk screen method, and a spray coating method. There are also no particular limitations on the drying method. Examples of the drying method include a heat drying method and an air drying method.

[0074] Another method for forming the adhesive layer includes, for example, preparing a resin liquid containing a monomer and a solvent for the polymer to be contained in the thermoplastic resin, applying the resin liquid to a suitable support surface to form a resin liquid film, drying the film, and polymerizing the monomer to obtain a polymer. This resin liquid may contain an organosilicon compound or any other component. After forming the resin liquid film, the monomer contained in the film can be polymerized by a polymerization process such as heating and exposure, thereby forming an adhesive layer from a thermoplastic resin containing a polymer.

[0075] [2.2.Support layer] The composite protective film includes a support layer in combination with the adhesive layer. The support layer can prevent foreign matter such as dust from adhering to the adhesive layer. Furthermore, the support layer usually provides the composite protective film with stable self-supporting properties, improving the handleability of the composite protective film.

[0076] A resin film is usually used as the support layer. The resin film can be formed from a resin containing a polymer. Examples of the polymer include polymers containing an alicyclic structure, such as norbornene-based polymers; polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate and polybutylene terephthalate; polyarylene sulfides such as polyphenylene sulfide; polyvinyl alcohol; polycarbonate; polyarylate; cellulose ester polymers, polyether sulfone; polysulfone; polyarylsulfone; polyvinyl chloride; and the like. The resin film may contain one type of polymer, or two or more types of polymers.

[0077] Typically, when using a composite glass sheet, the support layer is peeled off from the composite glass sheet. Therefore, from the viewpoint of smooth peeling of the support layer, a release film is preferred as the support layer. As the release film, for example, a film whose surface is treated with a release agent can be used. Examples of the release agent include silicon-based release agents such as polydimethylsiloxane, fluorine-based release agents such as alkyl fluorides, and long-chain alkyl-based release agents. Among them, silicon-based release agents are preferred from the viewpoint of releasability and processability. Furthermore, one type of release agent may be used alone, or two or more types may be used in combination.

[0078] The thickness of the support layer is not particularly limited, but is preferably 10 μm or more, more preferably 15 μm or more, and particularly preferably 20 μm or more, and is preferably 100 μm or less, more preferably 75 μm or less, and particularly preferably 50 μm or less.

[0079] [2.3.Flexible layer] The composite protective film preferably includes a flexible layer between the adhesive layer and the support layer. The flexible layer has a storage modulus smaller than that of the adhesive layer. A composite glass sheet manufactured using a composite protective film including a flexible layer can include the flexible layer. When the composite glass sheet is attached to an object such as an image display device, air can be prevented from remaining between the object and the flexible layer, thereby suppressing the formation of air bubbles. Furthermore, the flexible layer can usually increase the impact resistance of the composite protective film. Furthermore, when the composite protective film is provided on the surface of the object, the flexible layer can increase the impact resistance of the surface.

[0080] The difference between the storage modulus of the adhesive layer and the storage modulus of the flexible layer is usually greater than 0 MPa, preferably 10 MPa or more, more preferably 50 MPa or more, and particularly preferably 100 MPa or more. There is no particular upper limit, but from the viewpoint of suppressing the brittleness of the adhesive layer itself, it is preferably 5000 MPa or less, more preferably 3000 MPa or less, and particularly preferably 1000 MPa or less.

[0081] The storage modulus of the flexible layer is preferably 0.01 MPa or more, more preferably 0.05 MPa or more, and particularly preferably 0.1 MPa or more, from the viewpoints of adhesion between the composite glass sheet and the target article, impact resistance of the composite protective film, and bending resistance of the glass substrate, and is preferably 100 MPa or less, more preferably 50 MPa or less, and particularly preferably 10 MPa or less.

[0082] The storage modulus of the flexible layer can be measured at a frequency of 1 Hz using a dynamic viscoelasticity measuring device at a measurement temperature of 25° C. The difference between the storage modulus of the adhesive layer and the storage modulus of the flexible layer can be evaluated at a measurement temperature of 25° C.

[0083] The storage modulus of the flexible layer can be adjusted, for example, by adjusting the types and proportions of components contained in the flexible layer. In particular, the storage modulus can be easily adjusted by adjusting the proportion of the softener.

[0084] The flexible layer may be formed of a resin containing a polymer. Therefore, the flexible layer usually contains a resin, and preferably contains only a resin. The resin is preferably a thermoplastic resin.

[0085] Examples of polymers contained in the resin forming the flexible layer include the same polymers contained in the thermoplastic resin forming the adhesive layer. Furthermore, one type of polymer may be used alone, or two or more types may be used in combination. Among these, it is preferable that the resin forming the flexible layer contains a Si polymer. When a Si polymer is used, the adhesive strength between the target article made of an inorganic material such as glass and the flexible layer can be increased, thereby enabling the composite glass sheet to be particularly strongly attached to the target article.

[0086] The amount of polymer contained in the resin forming the flexible layer is preferably 40% by weight or more, more preferably 50% by weight or more, and particularly preferably 55% by weight or more, relative to 100% by weight of the resin, and is usually 100% by weight or less, preferably 95% by weight or less, and more preferably 90% by weight or less.

[0087] The resin forming the flexible layer preferably contains a softener in combination with the polymer. The softener can reduce the storage modulus of the flexible layer. Examples of the softener include the same softeners that can be used in the adhesive layer. Furthermore, one type of softener may be used alone, or two or more types may be used in combination.

[0088] The amount of the softener is preferably adjusted so that the storage modulus of the flexible layer falls within a desired range. The specific amount of the softener contained in the resin forming the flexible layer is preferably 20 parts by weight or more, more preferably 30 parts by weight or more, and particularly preferably 40 parts by weight or more, relative to 100 parts by weight of the polymer contained in the resin, and is preferably 100 parts by weight or less, more preferably 85 parts by weight or less, and particularly preferably 70 parts by weight or less.

[0089] The resin forming the flexible layer may further contain optional components in combination with the polymer and softener. Examples of optional components include the same components that may be contained in the adhesive layer. The amount of optional components may be the same as the amount in the thermoplastic resin forming the adhesive layer.

[0090] The thickness of the flexible layer is preferably 5 μm or more, more preferably 10 μm or more, and particularly preferably 15 μm or more from the viewpoint of adhesion between the composite glass sheet and the target article and impact resistance of the composite protective film. Also, the thickness of the flexible layer is preferably 100 μm or less, more preferably 85 μm or less, and particularly preferably 75 μm or less from the viewpoint of bending resistance of the glass substrate.

[0091] There are no particular limitations on the method for forming the flexible layer. For example, the flexible layer can be formed by a method including the steps of preparing a resin liquid containing a resin and a solvent, applying the resin liquid to an appropriate support surface to form a resin liquid film, and drying the film. In this method for forming the flexible layer, the solvent may be the same as the solvent for the resin liquid used to form the adhesive layer. There are no particular limitations on the concentration of the resin in the resin liquid used to form the flexible layer, but it may be the same as the concentration of the resin liquid used to form the adhesive layer. Furthermore, the support surface, the method for applying the resin liquid, and the drying method may be the same as those used in the method for forming the adhesive layer. The flexible layer may also be formed using a resin liquid containing a polymer monomer, for example, in the same manner as in the formation of an adhesive.

[0092] [2.4. Optional Layer] The composite protective film may further include any layer in addition to the adhesive layer, support layer, and flexible layer described above. However, from the viewpoint of making the composite protective film thin and effectively suppressing breakage due to bending of the glass substrate, it is preferable that the composite protective film does not include any layer. Therefore, it is preferable that the composite protective film includes only the adhesive layer and support layer, or only the adhesive layer, support layer, and flexible layer.

[0093] [2.5. Manufacturing method of composite protective film] There are no particular limitations on the method for producing the composite protective film. The composite protective film may be produced, for example, by a method including separately preparing each layer of the composite protective film, such as the adhesive layer, flexible layer, and support layer, and then bonding these layers together. Alternatively, the composite protective film may be produced, for example, by a method including sequentially forming other layers on the support layer.

[0094] However, if the adhesive layer of the composite protective film is exposed, foreign matter such as dust may adhere to the adhesive layer. Therefore, when the composite protective film is stored and transported without being attached to a glass substrate immediately after production, it is preferable that a release film be attached to the adhesive layer. Therefore, the composite protective film may be produced by a method including the steps of preparing a composite protective film laminate having a release film on the adhesive layer side of the composite protective film, and peeling the release film from the composite protective film laminate.

[0095] Fig. 2 is a cross-sectional view schematically showing a composite protective film laminate 200 according to one embodiment of the present invention. As shown in Fig. 2, the composite protective film laminate 200 according to one embodiment of the present invention includes a release film 210, an adhesive layer 110, and a support layer 120, in this order in the thickness direction. Furthermore, the composite protective film laminate 200 used to manufacture the composite protective film 100 (see Fig. 1) including the flexible layer 130 includes the release film 210, the adhesive layer 110, the flexible layer 130, and the support layer 120, in this order in the thickness direction. As the release film 210, for example, the same film as that described in the section regarding the support layer can be used.

[0096] The composite protective film laminate may be produced, for example, by a method including separately preparing each layer of the composite protective film laminate, such as the adhesive layer, flexible layer, support layer, and release film, and then bonding these layers together. Alternatively, the composite protective film may be produced, for example, by a method including sequentially forming other layers on the support layer or the release film. Specifically, the composite protective film laminate may be produced by a method including the steps of forming an adhesive layer on the release film to obtain a first laminate film, forming a flexible layer on the support layer to obtain a second laminate film, and bonding the adhesive layer of the first laminate film to the flexible layer of the second laminate film to obtain the composite protective film laminate.

[0097] Typically, this composite protective film laminate is stored and transported, and the release film is peeled off from the composite protective film laminate just before being laminated to a glass substrate to produce a composite protective film. Therefore, when composite protective films are distributed on the market, they are generally distributed in the form of a composite protective film laminate.

[0098] [3. Cutting the glass substrate] 3 is a side view schematically showing how a glass substrate is cut in a method for manufacturing a composite glass sheet according to an embodiment of the present invention. As shown in FIG. 3, the method for manufacturing a composite glass sheet according to an embodiment of the present invention includes a step of cutting a glass substrate 300.

[0099] From the viewpoint of obtaining a composite glass sheet having excellent flexibility, a thin sheet is preferable as the glass substrate 300. The thickness of the glass substrate 300 is preferably 500 μm or less, more preferably 200 μm or less, and particularly preferably 100 μm or less. There is no particular lower limit, but the lower limit is preferably 20 μm or more, more preferably 25 μm or more, and particularly preferably 30 μm or more.

[0100] The method for cutting the glass substrate 300 is not particularly limited. For example, a laser cutting method using a laser beam or a physical cutting method using a cutting device such as a diamond cutter can be used. Cutting the glass substrate 300 can also include cutting the glass substrate 300 to shape it. FIG. 3 shows an example in which the glass substrate 300 is cut using a laser beam 320 irradiated from a laser processing machine 310. It is preferable that the dimensions of the glass substrate 300 after cutting are appropriately set according to the dimensions of the composite glass sheet to be manufactured.

[0101] [4. Step of bonding a first protective film to one surface of the glass substrate] 4 is a side view schematically showing how a first protective film 400 and a second protective film 500 are bonded to a glass substrate 300 in a method for manufacturing a composite glass sheet according to one embodiment of the present invention. As shown in FIG. 4, the method for manufacturing a composite glass sheet according to one embodiment of the present invention includes a step of bonding a first protective film 400 to one surface 300U of the glass substrate 300 after cutting.

[0102] The above-described composite protective film is preferably used as the first protective film 400. Fig. 4 shows an example in which a composite protective film 100 including an adhesive layer 110, a flexible layer 130, and a support layer 120 in this order is used as the first protective film 400. When the composite protective film 100 is attached to a glass substrate 300, it is usually attached so that the adhesive layer 110 contacts a surface 300U of the glass substrate 300, as shown in Fig. 4.

[0103] When a composite protective film is used as the second protective film 500, a protective film other than the composite protective film may be used as the first protective film 400. Examples of the protective film other than the composite protective film include a resin film. Examples of the resin film include the same resin films used in the support layer. The protective film may also include an adhesive layer to facilitate bonding to the glass substrate 300.

[0104] The method for bonding the glass substrate 300 and the first protective film 400 is not particularly limited, and may be, for example, a pressure bonding method. The pressure applied when bonding the glass substrate 300 and the first protective film 400 is preferably set appropriately within a range that does not damage the glass substrate 300. Furthermore, if necessary, temperature adjustment such as heating and cooling may be performed when bonding the glass substrate 300 and the first protective film 400.

[0105] [5. Step of attaching a second protective film to the other side of the glass substrate] As shown in FIG. 4, the method for producing a composite glass sheet according to one embodiment of the present invention includes a step of bonding a second protective film 500 to the other surface 300D of the glass substrate 300 after cutting.

[0106] The above-described composite protective film is preferably used as the second protective film 500. When the composite protective film is attached to the glass substrate 300 as the second protective film 500, it is usually attached so that the adhesive layer is in contact with the surface 300D of the glass substrate 300.

[0107] When the composite protective film 100 is used as the first protective film 400, a protective film other than the composite protective film may be used as the second protective film 500. As the protective film, for example, the protective films described as being usable as the first protective film 400 may be used.

[0108] The method for bonding the glass substrate 300 and the second protective film 500 is not particularly limited, and can be the same method as the method for bonding the glass substrate 300 and the first protective film 400, for example.

[0109] [6. Period between the cutting process of the glass substrate and the lamination process of the composite protective film] The glass substrate and the composite protective film are preferably bonded together promptly after cutting the glass substrate. When the composite protective film is bonded to the glass substrate promptly after cutting, the period during which the glass substrate is exposed can be shortened, thereby preventing foreign matter such as dust from adhering to the surface of the glass substrate and preventing the surface of the glass substrate from being scratched.

[0110] When laminating a composite protective film quickly after cutting a glass substrate, typically, no solid material comes into contact with the surface of the glass substrate between the step of cutting the glass substrate and the step of laminating the surface of the glass substrate and the composite protective film. Therefore, during this period, no film such as a conventional cover film is laminated to the surface of the glass substrate (the surface to be laminated with the composite protective film). In order to perform the lamination quickly as described above, it is preferable that the glass substrate and the composite protective film be laminated in the factory where the glass substrate is cut.

[0111] In the above-described manufacturing method, the adhesive layer functions as a cover film to protect the glass substrate, eliminating the need for a separate cover glass, and thus eliminating the need for laminating and peeling the cover film, thereby reducing the number of manufacturing steps for the composite glass sheet.

[0112] [7. Optional Process] The method for producing a composite film may include an optional step in addition to the steps described above. The method for producing a composite film preferably includes, as an optional step, a step of storing the glass substrate and the composite protective film in a specific storage environment after the step of laminating the glass substrate and the composite protective film. Specifically, the method for producing a composite film preferably includes laminating both the first protective film and the second protective film to the glass substrate, and then storing the resulting composite protective film in a specific storage environment. Such storage may be referred to as "firing" as appropriate.

[0113] The temperature of the storage environment is usually 60°C or higher, preferably 65°C or higher, more preferably 70°C or higher, and preferably 130°C or lower, more preferably 100°C or lower, and particularly preferably 90°C or lower. The humidity of the storage environment is usually 60%RH or higher, preferably 65%RH or higher, more preferably 70%RH or higher, and preferably 95%RH or lower, more preferably 93%RH or lower, and particularly preferably 90%RH or lower. The storage time is preferably 10 minutes or longer, more preferably 20 minutes or longer, and particularly preferably 30 minutes or longer, and preferably 48 hours or shorter, more preferably 24 hours or shorter, and particularly preferably 12 hours or shorter.

[0114] Storage in the above-described storage environment can improve the adhesive strength between the glass substrate and the adhesive layer of the specific protective film. In particular, when the adhesive layer contains a Si polymer or a silane coupling agent containing an alkoxysilyl group, the adhesive strength can be effectively increased. The alkoxysilyl group can be hydrolyzed in the above-described storage environment to generate a hydroxysilyl group. The hydroxysilyl group can react with and bond to a hydroxy group on the surface of the glass substrate. Therefore, when stored in the above-described storage environment, the glass substrate and the adhesive layer can be bonded not only by physical adsorption but also by chemical bonding, thereby effectively improving the adhesive strength between the glass substrate and the adhesive layer of the specific protective film.

[0115] In addition, the manufacturing method of the composite film may include, for example, a step of subjecting the glass substrate to a cleaning treatment, a surface treatment, or a chemical strengthening treatment in which the glass substrate is immersed in a chemical solution before being bonded to the first protective film and the second protective film.

[0116] [8. Composite Glass Sheet] Fig. 5 is a cross-sectional view schematically showing a composite glass sheet produced by a production method according to one embodiment of the present invention. As shown in Fig. 5, the production method described above can produce a composite glass sheet 600 including a glass substrate 300, a first protective film 400 provided on one surface 300U of the glass substrate 300, and a second protective film 500 provided on the other surface 300D of the glass substrate 300.

[0117] In the above-described manufacturing method, the composite protective film 100 is used as at least one of the first protective film 400 and the second protective film 500. Therefore, the manufactured composite glass sheet 600 includes at least the glass substrate 300 and the adhesive layer 110, and preferably includes the glass substrate 300, the adhesive layer 110, and the flexible layer 130 in this order in the thickness direction. Furthermore, before the support layer 120 is peeled off, the composite glass sheet 600 includes at least the glass substrate 300, the adhesive layer 110, and the support layer 120 in this order in the thickness direction, and preferably includes the glass substrate 300, the adhesive layer 110, the support layer 120, and the flexible layer 130 in this order in the thickness direction.

[0118] Because the adhesive layer 110 is made of a thermoplastic resin containing a Si polymer or a thermoplastic resin containing an organosilicon compound, the adhesive layer 110 can be bonded to the glass substrate 300 with high adhesive strength. Furthermore, the adhesive layer 110 can protect the surface of the glass substrate 300 from adhesion of foreign matter and scratches. Furthermore, the support layer 120 can protect the glass substrate 300 and the adhesive layer 110 from adhesion of foreign matter and scratches. Therefore, there is no need to provide a cover film (not shown) to protect the glass substrate 300 during transportation and storage. Furthermore, when the flexible layer 130 is provided, it is possible to prevent damage to the glass substrate 300 due to impacts during transportation and storage.

[0119] One of the first protective film 400 and the second protective film 500 may be a film other than a composite protective film. Even in this case, the film can protect the glass substrate 300 during transportation and storage of the glass substrate 300.

[0120] FIG. 6 is a cross-sectional view schematically illustrating a composite glass sheet 610 during use according to one embodiment of the present invention. Typically, when the composite glass sheet 600 is used, the support layer 120 is peeled off. Furthermore, of the first protective film 400 and the second protective film 500, any protective film that is not a composite protective film may also be peeled off when the composite glass sheet 600 is used. In the following description, the composite glass sheet after the support layer 120 has been peeled off may be referred to as "610." This composite glass sheet 610 includes at least a glass substrate 300 and an adhesive layer 110, and preferably includes the glass substrate 300, adhesive layer 110, and flexible layer 130, in this order in the thickness direction.

[0121] Fig. 7 is a cross-sectional view schematically illustrating a composite glass sheet 610 according to an embodiment of the present invention during use. The composite glass sheet 610 can suppress breakage of the glass substrate 300 even when bent as shown in Fig. 7. Specifically, when the composite glass sheet 610 is bent with the adhesive layer 110 facing outward relative to the glass substrate 300 (i.e., the side to which a greater tensile force is applied upon bending), it is possible to suppress breakage of the glass substrate 300. In particular, this effect of suppressing breakage of the glass substrate 300 is particularly pronounced when a flexible layer 130 is provided.

[0122] The effect of suppressing breakage of the glass substrate 300 as described above can be expressed by fracture stress. The fracture stress can be measured by a ring bending test. In this ring bending test, a composite glass sheet is placed between a large-diameter ring and a small-diameter ring. At this time, the centers of the large-diameter ring and the small-diameter ring are aligned in the thickness direction. The small-diameter ring is then pressed in the thickness direction toward the large-diameter ring to bend the composite glass sheet, and the fracture stress is calculated from the load at which the glass substrate breaks. In this case, the fracture stress is given by the following equation (X):

[0123]

number

[0124] In formula (X), P represents the load, t represents the thickness of the glass substrate, ν represents the Poisson's ratio of the glass substrate, and R S represents the radius of the large ring, and R L represents the radius of the small diameter ring, and R represents the radius of the glass substrate. For example, the radius R of a square glass substrate with a side length L is expressed by the following formula (Y):

[0125]

number

[0126] The specific method for the ring bending test can be the method described in the Examples. In one example, the fracture stress of the composite glass sheet 610 can be preferably 900 MPa or more, more preferably 950 MPa or more, and particularly preferably 1000 MPa or more.

[0127] The composite glass sheet 610 can be attached to the surface of a target object (e.g., the screen of an image display device, not shown) and used as a protective member for protecting the surface. The composite glass sheet 610 may be attached to either surface of the target object. For example, when the adhesive layer 110 and the glass substrate 300 are attached in this order from the target object side, the adhesive layer 110 or the flexible layer 130 can bond the composite glass sheet 610 to the surface of the target object with high adhesive strength. Furthermore, when the glass substrate 300 and the adhesive layer 110 are attached in this order from the target object side, the glass substrate 300 can be protected from adhesion of foreign matter and scratches. In particular, when tensile stress is applied to the glass surface on the side where the adhesive layer is formed, it is possible to suppress breakage of the glass substrate due to bending. [Example]

[0128] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples and can be modified as desired without departing from the scope of the claims of the present invention and their equivalents. In the following description, "%" and "parts" representing amounts are by weight unless otherwise specified. Furthermore, the operations described below were carried out in air at room temperature and normal pressure (23°C, 1 atmosphere) unless otherwise specified.

[0129] In the following description, unless otherwise specified, "release PET film" refers to a 38 μm thick polyethylene terephthalate film ("MRV38" manufactured by Mitsubishi Chemical Corporation) whose surface has been subjected to a release treatment.

[0130] [Evaluation method] (Method for measuring molecular weight of polymer) The weight average molecular weight and molecular weight distribution of the polymer were measured by gel permeation chromatography using tetrahydrofuran as a solvent, in terms of polystyrene.

[0131] (Method for measuring the hydrogenation rate of hydrides) The hydrogenation rate of the hydride is 1 It was determined by H-NMR measurement.

[0132] (Method for measuring storage modulus) The storage modulus of the adhesive layer and the flexible layer was measured at a measurement temperature of 25°C using a dynamic viscoelasticity measuring device ("DMA7100" manufactured by Hitachi High-Tech Science Corporation) at a frequency of 1 Hz.

[0133] (Method for measuring breaking stress) The breaking stress of the composite glass sheet was measured by the ring bending test described below. Using a precision universal testing machine (Shimadzu Corporation's "Autograph AGS-X"), a ring-shaped upper indenter with a diameter of 6 mm and a ring-shaped lower indenter with a diameter of 12.5 mm were attached as concentric bending jigs. The upper and lower indenters were attached so that their central positions coincided. Furthermore, sheet samples of the composite glass sheets produced in the examples and comparative examples were placed so that the center of the composite glass sheet was at the center of the lower indenter. At this time, the composite glass sheet was placed so that the glass substrate was on the upper indenter side. The upper indenter was pressed at a pressing speed of 0.5 mm / min until the glass substrate of the composite glass sheet broke, and the fracture stress was measured. The higher the fracture stress, the better the composite glass sheet's ability to suppress breakage of the glass substrate due to bending.

[0134] [Production Example 1: Production of polymer having silicon atom-containing polar group] (Production of hydrogenated block copolymer) Using styrene as the aromatic vinyl compound and isoprene as the linear conjugated diene compound, a hydrogenated block copolymer (hydrogenated block copolymer) having a triblock structure in which polymer block [A] is bonded to both ends of polymer block [B] was produced by the following procedure.

[0135] A reactor equipped with a stirrer and thoroughly purged with nitrogen was charged with 256 parts of dehydrated cyclohexane, 25.0 parts of dehydrated styrene, and 0.615 parts of n-dibutyl ether, and 1.35 parts of n-butyllithium (15% cyclohexane solution) was added with stirring at 60°C to initiate polymerization. The reaction was continued for 60 minutes with stirring at 60°C. The polymerization conversion at this point was 99.5% (the polymerization conversion was measured by gas chromatography; the same applies hereinafter).

[0136] Next, 50.0 parts of dehydrated isoprene was added, and stirring was continued at the same temperature for 30 minutes, at which point the polymerization conversion was 99%. Thereafter, 25.0 parts of dehydrated styrene was further added and stirred at the same temperature for 60 minutes, at which point the polymerization conversion rate was nearly 100%. Next, 0.5 parts of isopropyl alcohol was added to the reaction solution to terminate the reaction, thereby obtaining a solution (i) containing a block copolymer. The block copolymer in the resulting solution (i) had a weight average molecular weight (Mw) of 44,900 and a molecular weight distribution (Mw / Mn) of 1.03.

[0137] Next, solution (i) was transferred to a pressure-resistant reactor equipped with a stirrer, and 4.0 parts of a silica-alumina-supported nickel catalyst (E22U, 60% nickel loading; manufactured by JGC Chemical Industries, Ltd.) as a hydrogenation catalyst and 350 parts of dehydrated cyclohexane were added and mixed. The atmosphere inside the reactor was replaced with hydrogen gas, and hydrogen was further supplied while stirring the solution. The hydrogenation reaction was carried out at a temperature of 170°C and a pressure of 4.5 MPa for 6 hours to hydrogenate the block copolymer, yielding solution (iii) containing the hydrogenated block copolymer (ii). The weight-average molecular weight (Mw) of the hydrogenated block copolymer (ii) in solution (iii) was 45,100, and the molecular weight distribution (Mw / Mn) was 1.04.

[0138] After completion of the hydrogenation reaction, solution (iii) was filtered to remove the hydrogenation catalyst. Then, 1.0 part of a xylene solution containing 0.1 part of a phosphorus-based antioxidant, 6-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propoxy]-2,4,8,10-tetrakis-t-butyldibenzo[d,f][1.3.2]dioxaphosphepine (Sumitomo Chemical Co., Ltd., "Sumilizer (registered trademark) GP"; hereinafter referred to as "antioxidant A"), was added and dissolved to the filtered solution (iii), to obtain solution (iv).

[0139] Next, solution (iv) was filtered through a ZetaPlus® Filter 30H (manufactured by Cuno, pore size 0.5 μm to 1 μm) and then through another metal fiber filter (pore size 0.4 μm, manufactured by Nichidai) to remove minute solids. The solvent cyclohexane, xylene, and other volatile components were removed from the filtered solution (iv) using a cylindrical concentrating dryer (product name "CONTROL", manufactured by Hitachi, Ltd.) at a temperature of 260°C and a pressure of 0.001 MPa or less. The solids were then extruded in a molten state into strands through a die directly connected to the concentrating dryer, cooled, and cut with a pelletizer to obtain 85 parts of pellets (v) containing the hydrogenated block copolymer and antioxidant A. The weight-average molecular weight (Mw) of the hydrogenated block copolymer (hydrogenated block copolymer) in the resulting pellets (v) was 45,000, and the molecular weight distribution (Mw / Mn) was 1.08. The hydrogenation rate was 99.9%.

[0140] (Production of silane-modified hydrogenated block copolymer) A mixture was obtained by adding 2.0 parts of vinyltrimethoxysilane and 0.2 parts of di-t-butyl peroxide to 100 parts of pellets (v). This mixture was kneaded using a twin-screw extruder at a barrel temperature of 210°C and a residence time of 80 to 90 seconds. The kneaded mixture was extruded and cut using a pelletizer to obtain pellets (vi) of the silane-modified hydrogenated block copolymer. A film-like test piece was prepared from this pellet (vi), and the glass transition temperature (Tg) was evaluated using the tan δ peak of a dynamic viscoelasticity measuring device, which was found to be 124°C.

[0141] [Example 1] (1-1. Manufacturing of composite protective film) An adhesive layer solution was prepared by mixing 20 parts of the silane-modified hydrogenated block copolymer pellets (vi) prepared in Preparation Example 1, 5 parts of polybutene as a softener, and 75 parts of ethylcyclohexane as a solvent. This adhesive solution was applied to a release PET film 1 and dried to obtain a laminated film 1 having a layer structure of adhesive layer (thickness 5 μm) / release PET film 1. The storage modulus of the adhesive layer was 180 MPa.

[0142] A flexible layer solution was prepared by mixing 24 parts of the silane-modified hydrogenated block copolymer pellets (vi) prepared in Preparation Example 1, 16 parts of polybutene as a softener, and 60 parts of ethylcyclohexane as a solvent. This flexible layer solution was applied to a release PET film 2 and dried to obtain a laminated film 2 having a layer structure of a flexible layer (thickness 45 μm) / release PET film 2. The storage modulus of the flexible layer was 5 MPa.

[0143] The adhesive layer of laminate film 1 and the flexible layer of laminate film 2 were bonded together to obtain a composite protective film laminate having a layer structure of release PET film 2 / flexible layer / adhesive layer / release PET film 1. Then, release PET film 1 was peeled off to obtain composite protective film 1 having a layer structure of release PET film 2 / flexible layer / adhesive layer.

[0144] (1-2. Cutting of glass substrate) A sheet-shaped glass substrate measuring 20 cm square and 50 μm thick was laser-cut into 5 cm square pieces using a carbonate ion laser. The resulting 5 cm square glass substrate was then laminated with a protective film without touching either of its main surfaces.

[0145] (1-3. Attaching the protective film) A resin film with an adhesive layer ("SPV-363" manufactured by Nitto Denko Corporation) was bonded to one side of this 5 cm square glass substrate as a second protective film. Furthermore, a composite protective film 1 was bonded to the other side of the glass substrate as a first protective film to obtain a composite glass sheet having a layer structure of second protective film / glass substrate / adhesive layer / flexible layer / release PET film 2. Thereafter, this composite glass sheet was baked for 30 minutes under conditions of a temperature of 85°C and a humidity of 85% RH.

[0146] The second protective film and the release PET film 2 were peeled off from the obtained composite glass sheet to obtain a sheet sample having a layer structure of glass substrate / adhesive layer / flexible layer.

[0147] [Example 2] (2-1. Manufacturing of composite protective film) A composite protective film 1 was produced in the same manner as in step (1-1) of Example 1.

[0148] (2-2. Cutting of glass substrate) A sheet-shaped glass substrate measuring 15 cm square, 0.4 mm thick, and with a Poisson's ratio of 0.22 was laser-cut into 5 cm square pieces using a carbonate ion laser. The resulting 5 cm square glass substrate was then laminated with a protective film without touching either of its main surfaces.

[0149] (2-3. Attaching the protective film) A resin film with an adhesive layer ("SPV-363" manufactured by Nitto Denko Corporation) was bonded to one side of this 5 cm square glass substrate as a second protective film. Furthermore, a composite protective film 1 was bonded to the other side of the glass substrate as a first protective film to obtain a composite glass sheet having a layer structure of second protective film / glass substrate / adhesive layer / flexible layer / release PET film 2. Thereafter, this composite glass sheet was baked for 30 minutes under conditions of a temperature of 85°C and a humidity of 85% RH.

[0150] The second protective film and release PET film 2 were peeled off from the obtained composite glass sheet to obtain a sheet sample having a layer structure of glass substrate / adhesive layer / flexible layer. The breaking stress of this sheet sample was measured by a ring bending test and was found to be 1100 MPa.

[0151] [Example 3] (3-1. Manufacturing of composite protective film) An adhesive layer solution was prepared by mixing 20 parts of the silane-modified hydrogenated block copolymer pellets (vi) prepared in Preparation Example 1, 5 parts of polybutene as a softener, and 75 parts of ethylcyclohexane as a solvent. This adhesive solution was applied to a release PET film 1 and dried to obtain a laminated film 1 having a layer structure of adhesive layer (thickness 5 μm) / release PET film 1. The storage modulus of the adhesive layer was 180 MPa.

[0152] A transparent adhesive resin film (25 μm thick, "CS9861US" manufactured by Nitto Denko Corporation) was attached as a flexible layer to the adhesive layer side of laminate film 1. The storage modulus of the flexible layer was 0.3 MPa. Furthermore, release PET film 2 was attached to the surface of the flexible layer to obtain a composite protective film laminate having a layer structure of release PET film 2 / flexible layer / adhesive layer / release PET film 1. Thereafter, release PET film 1 was peeled off to obtain composite protective film 2 having a layer structure of release PET film 2 / flexible layer / adhesive layer.

[0153] (3-2. Cutting glass substrate) A sheet-shaped glass substrate measuring 15 cm square, 0.4 mm thick, and with a Poisson's ratio of 0.22 was laser-cut into 5 cm square pieces using a carbonate ion laser. The resulting 5 cm square glass substrate was then laminated with a protective film without touching either of its main surfaces.

[0154] (3-3. Attaching the protective film) A resin film with an adhesive layer ("SPV-363" manufactured by Nitto Denko Corporation) was bonded to one side of this 5 cm square glass substrate as a second protective film. Furthermore, a composite protective film 2 was bonded to the other side of the glass substrate as a first protective film, to obtain a composite glass sheet having a layer structure of second protective film / glass substrate / adhesive layer / flexible layer / release PET film 2. Thereafter, this composite glass sheet was baked for 30 minutes under conditions of a temperature of 85°C and a humidity of 85% RH.

[0155] The second protective film and release PET film 2 were peeled off from the obtained composite glass sheet to obtain a sheet sample having a layer structure of glass substrate / adhesive layer / flexible layer. The breaking stress of this sheet sample was measured by a ring bending test and was found to be 1080 MPa.

[0156] [Comparative Example 1] (C1-1. Manufacturing of laminated film) A flexible layer solution was prepared by mixing 24 parts of pellets (v) containing the hydrogenated product of the block copolymer produced in Production Example 1, 16 parts of polybutene as a softener, and 60 parts of ethylcyclohexane as a solvent. This flexible layer solution was applied to a release PET film 2 and dried to obtain a laminated film C1 having a layer structure of a flexible layer (thickness 50 μm) / release PET film 2. The storage modulus of the flexible layer was 5 MPa.

[0157] (C1-2. Cutting glass substrate) A sheet-shaped glass substrate measuring 15 cm square, 0.4 mm thick, and with a Poisson's ratio of 0.22 was laser-cut into 5 cm square pieces using a carbonate ion laser. The resulting 5 cm square glass substrate was then laminated with a protective film without touching either of its main surfaces.

[0158] (C1-3. Attaching the protective film) A resin film with an adhesive layer ("SPV-363" manufactured by Nitto Denko Corporation) was attached to one side of this 5 cm square glass substrate as a second protective film. Furthermore, laminated film C1 was attached to the other side of the glass substrate as a first protective film, yielding a composite glass sheet having a layer structure of second protective film / glass substrate / flexible layer / release PET film 1. This composite glass sheet was then baked for 30 minutes at a temperature of 85°C and a humidity of 85%RH.

[0159] The second protective film and release PET film 1 were peeled off from the obtained composite glass sheet to obtain a sheet sample having a layer structure of glass substrate / flexible layer. The breaking stress of this sheet sample was measured by a ring bending test and was found to be 830 MPa.

[0160] Comparative Example 2 (C2-1. Manufacturing of laminated film) An adhesive layer solution was prepared by mixing 20 parts of pellets (v) containing the hydrogenated product of the block copolymer produced in Production Example 1, 5 parts of polybutene as a softener, and 75 parts of ethylcyclohexane as a solvent. This adhesive solution was applied to a release PET film 1 and dried to obtain a laminated film C2 having a layer structure of adhesive layer (thickness 5 μm) / release PET film 1. The storage modulus of this adhesive layer was 185 MPa.

[0161] A transparent adhesive resin film (thickness 25 μm, "CS9861US" manufactured by Nitto Denko Corporation) was attached as a flexible layer to the adhesive layer side of laminated film C2 to obtain laminated film C3 having a layer structure of flexible layer / adhesive layer / release PET film 1. The storage modulus of the flexible layer was 0.3 MPa.

[0162] (C2-2. Cutting of glass substrate) A sheet-shaped glass substrate measuring 15 cm square, 0.4 mm thick, and with a Poisson's ratio of 0.22 was laser-cut into 5 cm square pieces using a carbonate ion laser. The resulting 5 cm square glass substrate was then laminated with a protective film without touching either of its main surfaces.

[0163] (C2-3. Attaching the protective film) A resin film with an adhesive layer ("SPV-363" manufactured by Nitto Denko Corporation) was attached to one side of this 5 cm square glass substrate as a second protective film. Furthermore, multilayer film C3 was attached to the other side of the glass substrate as a first protective film, yielding a composite glass sheet having a layer structure of second protective film / glass substrate / adhesive layer / flexible layer / release PET film 1. This composite glass sheet was then baked for 30 minutes at a temperature of 85°C and a humidity of 85% RH.

[0164] The second protective film and release PET film 1 were peeled off from the obtained composite glass sheet to obtain a sheet sample having a layer structure of glass substrate / adhesive layer / flexible layer. The breaking stress of this sheet sample was measured by a ring bending test and was found to be 830 MPa.

[0165] Comparative Example 3 The fracture stress of a sheet-shaped glass substrate measuring 5 cm square, 0.4 mm thick, and with a Poisson's ratio of 0.22 was measured by a ring bending test and found to be 820 MPa.

[0166] [result] The results of the above-mentioned Examples and Comparative Examples are shown in the table below.

[0167] [Table 1]

[0168] [Examples 4 to 6] The composite glass sheets of Examples 4 to 6 were manufactured in the same manner as Examples 1 to 3, except that the step of firing the composite glass sheet for 30 minutes under conditions of a temperature of 85°C and a humidity of 85% RH was not performed. When the adhesive layer of the composite glass sheet was manually peeled off from the glass substrate, it was found that the composite glass sheets of Examples 1 to 3 required a significantly greater force to peel off the adhesive layer than the composite glass sheets of Examples 4 to 6. This result confirmed that the adhesive strength between the glass substrate and the adhesive layer was improved by firing. [Explanation of symbols]

[0169] 100 Composite Protective Film 110 Adhesive layer 120 Support layer 130 Flexible layer 200 Composite protective film laminate 210 Release film 300 glass substrate 300U Glass substrate surface 300D glass substrate surface 310 Laser Processing Machine 320 Laser Light 400 First Protective Film 500 Secondary Protective Film 600 composite glass sheet 610 Composite Glass Sheet

Claims

1. cutting the glass substrate; a step of laminating a first protective film on one surface of the glass substrate; and bonding a second protective film to the other surface of the glass substrate, At least one of the first protective film and the second protective film is a composite protective film including an adhesive layer and a support layer, A method for producing a composite glass sheet, wherein the adhesive layer is made of a thermoplastic resin containing a polymer having an alkoxysilyl group.

2. The method of claim 1 , wherein the adhesive layer has a thickness of less than 10 μm.

3. The method for manufacturing a composite glass sheet according to claim 1 or 2, wherein the composite protective film comprises a flexible layer between the adhesive layer and the support layer, the flexible layer having a storage modulus smaller than that of the adhesive layer.

4. The method for producing a composite glass sheet according to any one of claims 1 to 3, wherein the support layer is a release film.

5. The method for manufacturing a composite glass sheet according to any one of claims 1 to 4, wherein no solid comes into contact with the surface of the glass substrate between the step of cutting the glass substrate and the step of bonding the surface of the glass substrate and the composite protective film.

6. A composite glass sheet comprising a glass substrate, a first protective film provided on one surface of the glass substrate, and a second protective film provided on the other surface of the glass substrate, At least one of the first protective film and the second protective film is a composite protective film including an adhesive layer and a support layer, The adhesive layer is made of a thermoplastic resin containing a polymer having an alkoxysilyl group.

7. 7. The composite glass sheet of claim 6, wherein the adhesive layer has a thickness of less than 10 μm.

8. 8. A composite glass sheet according to claim 6 or 7, further comprising a flexible layer between the adhesive layer and the support layer, the flexible layer having a storage modulus lower than that of the adhesive layer.

9. The composite glass sheet according to any one of claims 6 to 8, wherein the support layer is a release film.

10. A composite protective film laminate including a release film, an adhesive layer, a flexible layer, and a support layer in this order, the adhesive layer is made of a thermoplastic resin containing a polymer having an alkoxysilyl group, A composite protective film laminate, wherein the compliant layer has a lower storage modulus than the adhesive layer.

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