JP2022035841A - Laminate - Google Patents

Abstract

To provide a laminate of an extremely thin glass and a resin layer which is excellent in bending resistance and impact resistance and is also excellent in surface hardness and texture.SOLUTION: A laminate includes a glass substrate, and a resin layer provided so as to come in contact with one main surface of the glass substrate, in which the resin layer contains a polymer having an imide structure, the resin layer has a tensile elastic modulus when used as a single layer film of 1-15% with respect to a bending elastic modulus of the single glass substrate, a thickness of the glass substrate is 25-100 μm, the resin layer has a thickness of 6-100% with respect to the thickness of the glass substrate, and adhesion between the glass substrate and the resin layer is 2B or more in cross-cut peeling test evaluation according to ASTM D 3559-B.SELECTED DRAWING: Figure 1

Description

The present invention relates to a laminated body, and more particularly to a laminated body having a laminated structure of a glass substrate / resin layer suitable as a cover glass for a flexible display element.

In the field of display elements such as liquid crystal displays (LCDs) and organic EL displays (OLEDs) and electronic devices such as electronic paper, flexible panels having flexibility have begun to be adopted in addition to conventional flat panels. Particularly in recent years, the development of electronic devices equipped with foldable displays has been promoted.

It has been proposed to use an organic polymer material such as polyimide instead of the conventional glass substrate for the cover glass of the flexible device as described above, and some of them have been put into practical use. However, since these polymer materials are inferior in rigidity and hardness as compared with glass, there are problems that wrinkles and twists occur and the surface is easily scratched when they are repeatedly bent when used for a flexible panel.

It has also been proposed to make the display panel flexible by making the conventional glass substrate into ultrathin glass of about several tens of microns. Although ultra-thin glass has a certain bending radius, it has problems such as low compressive strength and impact resistance, which are characteristics peculiar to glass. Therefore, in recent years, attempts have been made to use chemically strengthened ultrathin glass.

However, although chemically strengthened ultrathin glass is relatively strong in compressive strength, bending strength, impact resistance, etc., it is inferior in puncture resistance (damage resistance when pressed with a pointed object). In fact, a structure in which chemically strengthened ultrathin glass is sandwiched between a protective film such as a polyester film via flexible adhesiveness has been proposed.

By the way, also in the technical field of a display substrate, it has been proposed to use a composite substrate in which a polyimide resin layer is laminated on a glass substrate as a material having both water vapor barrier characteristics and flexibility (for example, Patent Documents). 1-3).

Special Table 2002-534305 Gazette Special Table 2015-533685 Japanese Unexamined Patent Publication No. 2019-214159

Although a laminated body in which a resin film is laminated on a bendable ultra-thin glass has been proposed for applications such as a cover glass of a display used for a flexible device, as described above, a resin film is taken in consideration of glass breakage. Or, a soft and highly shock-absorbing material is used for the adhesive. Therefore, when used as a cover glass, the surface hardness is insufficient, the ultra-thin glass is damaged due to insufficient puncture resistance, and deformation marks due to bending and compression remain without being restored, which is required for displays. There is also a problem that the texture such as flatness and luxury is impaired.

The present invention has been made based on such a problem, and an object of the present invention is to provide an ultrathin glass / resin layer laminate having excellent bending resistance and impact resistance as well as surface hardness and texture. To provide.

To solve the above problems, the present inventors use a polymer having an imide structure in the resin layer, the physical characteristic value of the polymer is in a specific range, and the physical characteristic value has a specific relationship with the glass substrate. If so, it was found that the above problem can be solved. The present invention has been completed based on such findings. That is, the gist of the present invention is as follows.

[1] A laminate comprising a glass substrate and a resin layer provided in contact with one of the main surfaces of the glass substrate.
The resin layer contains a polymer having an imide structure and comprises.
When the resin layer is a single-layer film, the tensile elastic modulus is 1 to 15% with respect to the flexural modulus of the glass substrate alone.
The thickness of the glass substrate is 25 to 100 μm, and the thickness of the glass substrate is 25 to 100 μm.
The resin layer has a thickness of 6 to 100% with respect to the thickness of the glass substrate.
A laminate, characterized in that the adhesion between the glass substrate and the resin layer is 2B or more in the cross-cut peeling test evaluation according to ASTM D 3559-B.
[2] The laminate according to [1], wherein the glass substrate alone has a flexural modulus of 50 to 150 GPa.
[3] The laminate according to [1] or [2], wherein the tensile elastic modulus of the entire laminate is 5 GPa or more, or the flexural modulus is 10 GPa or more.
[4] The laminate according to any one of [1] to [3], wherein the total thickness of the glass substrate and the resin layer is 30 to 135 μm.
[5] The laminate according to any one of [1] to [4], wherein the glass substrate is chemically tempered glass.
[6] The laminate according to any one of [1] to [5], which is used as a cover glass for a flexible display element.

The laminate according to the present invention uses a polymer having an imide structure in a range having a specific range of physical property values and a range in which the physical property values have a specific relationship with a glass substrate as a resin layer, and is made of ultrathin glass having a predetermined thickness. By forming the structure laminated with the substrate, it is possible to obtain an ultrathin glass / resin layer laminate having excellent bending resistance and impact resistance, as well as excellent surface hardness and texture.

Schematic cross-sectional view schematically showing an embodiment of a laminate according to the present invention. Schematic cross-sectional view schematically showing another embodiment of the laminate according to the present invention. Schematic cross-sectional view schematically showing another embodiment of the laminate according to the present invention.

Aspects for carrying out the invention

The laminate according to the present invention will be described with reference to the drawings. 1 to 3 are schematic cross-sectional views schematically showing an embodiment of the laminated body of the present invention. As shown in FIG. 1, the laminate 1 according to the present invention includes a glass substrate 10 and a resin layer 20 provided on one of the main surfaces of the glass substrate 10 so as to be in contact with the surface 10A. According to one embodiment of the laminated body of the present invention, the laminated body may be provided with the functional layer 30 on the outermost surface 20A of the resin layer, as shown in FIG. Further, according to one embodiment of the laminated body of the present invention, the laminated body may be provided with the support 40 on the other main surface 10B side of the glass substrate as shown in FIG. Although not shown, in the embodiment shown in FIG. 3, the glass substrate 10 and the support 40 may be laminated via an adhesive. Hereinafter, each layer constituting the laminated body of the present invention will be described in detail.

<Glass substrate>
The glass substrate constituting the laminate of the present invention has a thickness of 25 to 100 μm. A glass substrate having a thickness of 25 to 100 μm can be a laminated body having bending resistance and impact resistance. The thickness of the glass substrate is preferably 30 to 70 μm from the viewpoint of achieving both manufacturing cost and bending resistance and impact resistance.

The glass substrate can be used without particular limitation as long as it has the above thickness, but silicate glass and silica glass are preferable, and borosilicate glass, sodalime glass, and aluminosilicate glass are more preferable. , Particularly preferably non-alkali glass. The non-alkali glass is a glass that does not substantially contain an alkaline component (alkali metal oxide), and specifically, a glass having a weight ratio of an alkaline component of 3000 ppm or less. The weight ratio of the alkaline component is preferably 1000 ppm or less, more preferably 500 ppm or less, and most preferably 300 ppm or less.

In the present invention, the glass substrate is preferably chemically strengthened glass. Chemically tempered glass is obtained by chemically strengthening the above-mentioned glass material. The chemical strengthening treatment can be carried out by a conventionally known method. For example, by immersing the glass substrate in a melt of a metal salt (eg, potassium nitrate) containing metal ions with a large ionic radius, the metal ions with a small ionic radius (typically Na ions or Li) in the glass substrate. Ions) are replaced by metal ions with a large ionic radius, which can result in residual compressive stress on the surface of the glass substrate. Chemically tempered glass is superior in compression strength, bending strength, and impact resistance to non-chemically tempered glass.

The flexural modulus of the glass substrate is preferably 50 to 150 GPa, more preferably 70 to 100 GPa. In this specification, the flexural modulus means a value measured at 25 ° C. in accordance with JIS R 1602: 1995.

As the glass substrate as described above, a commercially available glass substrate may be used, for example, Dragontrail (registered trademark) (manufactured by AGC Co., Ltd .: material = aluminum silicate, silicon content, thickness = 70 μm), SCHOTT AS 87 eco (SCHOTT). Manufactured by: Material = Aluminosilicate, Thickness = 25 μm, 50 μm, 70 μm), SCHOTT Xensation (registered trademark) Up (manufactured by SCHOTT: Material = Aluminosilicate, Thickness = 30 μm, 50 μm, 70 μm), D263 (registered trademark) Teco (manufactured by SCHOTT: material = borosilicate, thickness = 30 μm, 70 μm), G-Leaf (registered trademark) manufactured by Nippon Electric Glass Co., Ltd .: material = non-alkali glass, thickness = 50 μm, 100 μm) and the like. ..

<Resin layer>
The resin layer provided so as to be in contact with one of the main surfaces of the glass substrate contains a polymer having an imide structure. The polymer having an imide structure is not particularly limited as long as it has the physical characteristics described later, but polyimide is preferable.

When the resin layer is a single-layer film, the tensile elastic modulus of the single-layer film is 1 to 15% with respect to the bending elastic modulus of the glass substrate alone. Although not bound by theory, a glass substrate is generally a material having a higher flexural modulus and less flexibility than a resin, but the tensile modulus with respect to the flexural modulus of the glass substrate is 1 to 15%. It is considered that by laminating the resin film in the range of 1 in contact with the glass substrate, it is possible to obtain a laminated body having excellent surface hardness and texture while maintaining bending resistance and impact resistance. The tensile elastic modulus of the resin layer in the case of a single-layer film is preferably in the range of 2 to 10% with respect to the flexural modulus of the glass substrate. In the present specification, the tensile elastic modulus means a value measured at 25 ° C. in accordance with JIS K 7161.

Further, the resin layer needs to have a thickness of 6 to 100% with respect to the thickness of the glass substrate. If the resin layer is too thin than the above range, the bending resistance and impact resistance of the laminated body will be insufficient. On the other hand, if the resin layer is too thick than the above range, it becomes difficult to improve the surface hardness and texture while maintaining bending resistance and impact resistance. The preferred thickness of the resin layer is in the range of 14 to 67% with respect to the thickness of the glass substrate.

The thickness of the resin layer is not particularly limited as long as it has the above-mentioned relationship with the glass substrate, but from the viewpoint of achieving both adhesion to the glass substrate and surface hardness in the case of a laminated body, 5 to 5 to It is preferably 25 μm, preferably 10 to 20 μm. The total thickness of the glass substrate and the resin layer is preferably 30 to 135 μm, more preferably 40 to 70 μm.

From the viewpoint of forming a laminate with excellent bending resistance and impact resistance, as well as excellent surface hardness and texture, the adhesion between the glass substrate and the resin layer is evaluated by a cross-cut peeling test based on ASTM D 3559-B. It is necessary to be 2B or more in. In particular, from the viewpoint of achieving both bending resistance and surface hardness, 3B to 5B is preferable.

Further, when the resin layer is a single-layer film having a thickness of 50 μm, the total light transmittance of the single-layer film is preferably 88% or more. When the total light transmittance is 88% or more, the laminate can be suitably used as a cover glass for a display for a flexible device. It is more preferable that the total light transmittance is 90% or more. In this specification, the total light transmittance means a value measured by a known turbidity meter in accordance with JIS K 7375: 2008.

Further, when the resin layer is a single-layer film having a thickness of 50 μm, the YI value of the single-layer film is preferably 2.0 or less. By forming the resin layer having a high total light transmittance and a small YI value as described above, the laminate can be more preferably used as a cover glass for a display for a flexible device. The YI value is more preferably 1.5 or less. In this specification, the YI value (yellowness) is determined by measuring the transmittance for light of 300 to 800 nm using an ultraviolet-visible near-infrared spectrophotometer in accordance with JIS K 7373: 2006, and tristimulating the three stimuli. It is assumed that the value (X, Y, Z) is obtained and means the value calculated based on the formula of YI = 100 × (1.2769X-1.592Z) / Y.

Further, when the resin layer is a single-layer film having a thickness of 50 μm, the haze of the single-layer film is preferably 2.0 or less. By using a resin layer having a small haze in addition to the total light transmittance and the YI value, the laminate can be more preferably used as a cover glass for a display for a flexible device. The haze is more preferably 1.0 or less. In this specification, haze means a value measured by a known turbidity meter in accordance with JIS K 7136: 2000.

The resin layer having the above-mentioned physical characteristics can be realized by using the polyimide represented by the following formula (1) as the polymer having an imide structure. The structural unit represented by the formula (1) is a structural unit formed by reacting a tetracarboxylic acid compound and a diamine compound.

In the above formula (1), X represents a divalent organic group independently of each other, preferably a divalent organic group having 4 to 40 carbon atoms, and more preferably 2 having a cyclic structure and 4 to 40 carbon atoms. Represents a valent organic group. Examples of the cyclic structure include an alicyclic ring, an aromatic ring, and a heterocyclic structure.
In the organic group, the hydrogen atom in the organic group may be substituted with a hydrocarbon group or a hydrocarbon group substituted with fluorine, in which case the carbon number of the hydrocarbon group and the hydrocarbon group substituted with fluorine is preferable. It is 1 to 8.
In the embodiment of the present invention, the polyimide may contain a plurality of types of X, and the plurality of types of X may be the same as or different from each other.
As X, a group represented by the following formula can be exemplified, in which a hydrogen atom is substituted with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group in each group, and a chain hydrocarbon having 6 or less carbon atoms. The group can be exemplified.

In the above equation, * represents a bond, and A ¹ , A ² , and A ³ are independent of each other and are single bonds, -O-, -S-, -CH _{2-, -CH 2 -} CH _2- , -CH (CH ₃ )-, -C (CH ₃ ) _2- , -C (CF ₃ ) _2- , -SO _2- , -CO- or N (Q)-represented. Here, Q represents a monovalent hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a halogen atom.
As an example, A ¹ and A ³ are single bonds, -O- or -S-, and A ² is -CH _2- , -C (CH ₃ ) _2- , -C (CF ₃ ) ₂ -or. SO _2- . The binding positions of A ¹ and A ² for each ring and the binding positions of A ² and A ³ for each ring are independent of each other, preferably in the meta or para position for each ring, and more. It is preferably in the para position.

で表される基がより好ましい。
また、Ａ^１、Ａ^２およびＡ^３は、積層体の表面硬度および柔軟性を高めやすい観点から、互いに独立して、単結合、－Ｏ－またはＳ－であることが好ましく、単結合またはＯ－であることがより好ましい。 Among the above groups, from the viewpoint of surface hardness and bending resistance of the laminated body, the following formula:

The group represented by is more preferable.
Further, A ¹ , A ² and A ³ are preferably single bonds, —O— or S— independently of each other, and are single bonds or O—, from the viewpoint of easily increasing the surface hardness and flexibility of the laminate. -It is more preferable.

In a preferred embodiment of the present invention, at least a part of the plurality of Xs in the above formula (1) is a structural unit represented by the formula (2).

In the formula (2), * represents a bond, and R ¹ to R ⁸ are independent of each other, and are a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or 6 to 6 carbon atoms. The hydrogen atoms represented by 12 aryl groups and contained in R ¹ to R ⁸ may be substituted with halogen atoms independently of each other.

R ¹ to R ⁸ independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, where R ¹ is used. The hydrogen atoms contained in ~ R ⁸ may be substituted with halogen atoms independently of each other. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom. Independent of each other, R ¹ to R ⁸ are more preferably a hydrogen atom, a methyl group, a fluoro group, a chloro group or a trifluoromethyl group from the viewpoint of surface hardness, transparency and bending resistance of the laminate. Particularly preferably, R ¹ , R ³ , R ⁴ , R ⁵ , R ⁶ and R ⁸ are hydrogen atoms, and R ² and R ⁷ are hydrogen atoms, methyl groups, fluoro groups, chloro groups or trifluoromethyl groups, in particular. Preferably R ² and R ⁷ are methyl or trifluoromethyl groups.

In a preferred embodiment of the present invention, the structural unit represented by the above formula (2) is the structural unit represented by the formula (3). That is, at least a part of the plurality of Xs is a structural unit represented by the equation (3). In this case, the skeleton containing the elemental fluorine enhances the solubility of the polyimide in the solvent, and it is easy to improve the storage stability of the varnish containing the polyimide, and it is easy to reduce the viscosity of the varnish. It is easy to improve the coatability. Further, the skeleton containing a fluorine element improves the optical characteristics (total light transmittance, YI value, haze, etc.) of the laminated body.

In one embodiment of the present invention, the amount of X in the polyimide is preferably 30 mol% or more, more preferably 50 mol% or more, still more preferably 70 mol% or more, of the formula (2), particularly the formula (3). It is represented by. When X in the above range in the polyimide is represented by the formula (2), particularly the formula (3), the solubility in the solvent is easily improved by the skeleton containing the fluorine element, and the storage stability of the varnish containing the polyimide is stable. It is easy to improve the property, and it is easy to reduce the viscosity of the varnish, and the coatability is improved. In addition, the skeleton containing a fluorine element improves optical characteristics such as total light transmittance, YI value, and haze. The ratio of the structural units represented by the formula (2) or (3) of X in the polyimide can be measured by using, for example, ¹ H-NMR, but of course, it should also be calculated from the charging ratio of the raw materials. You can also.

In the above formula (1), Y represents a tetravalent organic group, preferably a tetravalent organic group having 4 to 40 carbon atoms, and more preferably a tetravalent organic group having a cyclic structure and having 4 to 40 carbon atoms. Represents a group. Examples of the cyclic structure include an alicyclic ring, an aromatic ring, and a heterocyclic structure. The organic group is an organic group in which the hydrogen atom in the organic group may be substituted with a hydrocarbon group or a hydrocarbon group substituted with fluorine, in which case the carbon of the hydrocarbon group and the hydrocarbon group substituted with fluorine is substituted. The number is preferably 1-8.

In one embodiment of the present invention, the polyimide may contain a plurality of types of Y, and the plurality of types of Y may be the same as or different from each other. As Y, a group represented by the following formula is preferable. In these exemplified groups, a group in which a hydrogen atom is substituted with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group; and a chain hydrocarbon group having a tetravalent carbon number of 6 or less are exemplified.

In the above formula, * represents a bond, B ¹ is a single bond, -O-, -CH _{2-, -CH 2 -} CH _2- , -CH (CH ₃ )-, -C (CH ₃ ) ₂ . -, -C (CF ₃ ) _2- , -Ar-, -SO _2- , -CO-, -O-Ar-O-, -Ar-O-Ar-, -Ar-CH ₂ -Ar-,- Represents Ar-C (CH ₃ ) ₂ -Ar- or Ar-SO ₂ -Ar-. Ar represents an arylene group having 6 to 20 carbon atoms in which a hydrogen atom may be substituted with a fluorine atom, and specific examples thereof include a phenylene group.

Among the above groups, the group represented by the following formula is preferable from the viewpoint of the surface hardness and bending resistance of the laminated body. From the viewpoint of easily increasing the surface hardness and bending resistance of the laminate and easily reducing the yellowness, single bonds, -O-, -CH _{2-, -CH 2 -} CH _2- , -CH ( CH ₃ )-, -C (CH ₃ ) _2- or C (CF ₃ ) _2- , preferably single bond, -O-, -CH _2- , -CH (CH ₃ )-, -C ( It is more preferably CH ₃ ) _2- or C (CF ₃ ) _2- , and even more preferably single bond, -C (CH ³ ) _2- or C (CF ₃ ) _2- .

In one embodiment of the present invention, at least a part of the plurality of Ys in the formula (1) is a structural unit represented by the following formula (4). When at least a part of the plurality of Ys in the formula (1) is a group represented by the formula (4), the solubility of the polyimide in the solvent is enhanced, the viscosity of the varnish containing the polyimide can be easily reduced, and the coating is applied. Sex improves. In addition, the optical characteristics of the laminated body are improved.

In formula (5), * represents a bond, and R ⁹ to R ¹⁶ are independent of each other, a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or 6 to 6 carbon atoms. The hydrogen atoms represented by 12 aryl groups and contained in R ⁹ to R ¹⁶ may be substituted with halogen atoms independently of each other. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.
From the viewpoint of easily improving the surface hardness, bending resistance and optical properties of the laminate, R ⁹ to R ¹⁶ are independent of each other, and more preferably a hydrogen atom, a methyl group, a fluoro group, a chloro group or a trifluoromethyl group. Particularly preferably, R ⁹ , R ¹⁰ , R ¹¹ , R ¹⁴ , R ¹⁵ and R ¹⁶ are hydrogen atoms, and R ¹² and R ¹³ are hydrogen atoms, methyl groups, fluoro groups, chloro groups or trifluoromethyl groups. Yes, and particularly preferably R ¹² and R ¹³ are methyl or trifluoromethyl groups.

In one embodiment of the present invention, the structural unit represented by the above formula (4) is preferably a group represented by the following formula (5). The skeleton containing a fluorine element enhances the solubility of polyimide in a solvent, and it is easy to improve the storage stability of the varnish containing polyimide, and it is easy to reduce the viscosity of the varnish, and the coatability is improved. Further, the skeleton containing a fluorine element improves the optical characteristics of the laminated body.

In one embodiment of the present invention, Y in the polyimide is preferably 50 mol% or more, more preferably 60 mol% or more, still more preferably 70 mol% or more, represented by the formula (4), particularly the formula (5). Will be done. When Y in the above range in the polyimide is represented by the formula (4), particularly the formula (5), the skeleton containing the elemental fluorine enhances the solubility of the polyimide in the solvent and reduces the viscosity of the resin-containing varnish. It is easy to do, and it is easy to improve the workability of the resin layer. Further, the skeleton containing a fluorine element makes it easy to improve the optical characteristics of the laminated body. It should be noted that preferably, 100 mol% or less of Y in the polyimide is represented by the formula (4), particularly the formula (5). Y in the polyimide may be of the formula (4), particularly of the formula (5). The ratio of the structural unit represented by the formula (4) of Y in the polyimide can be measured by using, for example, ¹ H-NMR, but of course, it can also be calculated from the charging ratio of the raw materials.

The above-mentioned polyimide can include a structural unit represented by the formula (30) and / or a structural unit represented by the formula (31) in addition to the structural unit represented by the formula (1).

In the formula (30), Y1 is a tetravalent organic group, preferably an organic group in which a hydrogen atom in the organic group may be substituted with a hydrocarbon group or a hydrocarbon group substituted with fluorine. As Y ¹ , the above-mentioned preferable group of Y can be exemplified. In one embodiment of the present invention, the polyimide may contain a plurality of types of Y ^1s , and the plurality of types of Y ^1s may be the same as or different from each other.

In the formula (31), Y ² is a trivalent organic group, preferably an organic group in which a hydrogen atom in the organic group may be substituted with a hydrocarbon group or a hydrocarbon group substituted with fluorine. Examples of Y ² include a group in which any one of the above-mentioned bonds of the preferred group of Y is replaced with a hydrogen atom, and a chain hydrocarbon group having a trivalent carbon number of 6 or less. In one embodiment of the present invention, the polyimide may contain a plurality of types of Y ² , and the plurality of types of Y ² may be the same or different from each other.

In the formula (30) and the formula (31), X ¹ and X ² are divalent organic groups independently of each other, preferably a hydrocarbon group in which a hydrogen atom in the organic group is substituted with a hydrocarbon group or fluorine. It is an organic group that may be substituted with. As X ¹ and X ² , the above-mentioned preferable group of X can be exemplified.

In one embodiment of the invention, the polyimide comprises a structural unit represented by the formula (1) and, optionally, a structural unit represented by the formula (30) and / or the formula (31). Further, from the viewpoint of the optical properties, surface hardness and bending resistance of the laminated body, the structural units represented by the formula (1) in the above-mentioned polyimide are the formula (1), and in some cases, the formula (30) and the formula (31). ), It is preferably 80 mol% or more, more preferably 90 mol% or more, still more preferably 95 mol% or more, based on all the constituent units represented by). In polyimide, the structural unit represented by the formula (1) is usually 100% based on the formula (1) and, in some cases, all the structural units represented by the formula (30) and / or the formula (31). It is as follows. The above ratio can be measured using, for example, ¹ H-NMR, or can be calculated from the charging ratio of raw materials.

Further, in one embodiment of the present invention, from the viewpoint of the adhesion between the resin layer and the glass substrate and the texture of the laminated body, the polyimide is a structural unit represented by the formula (1), and in some cases, the formula (30) and / Or, in addition to the structural unit represented by the formula (31), the structural unit represented by the following formula (40) may be included.

In the above formula (40), * represents a bond, and R ¹⁷ and R ¹⁸ are independently single bonds, alkylene groups having 1 to 5 carbon atoms, or divalent aromatic groups having 6 or more carbon atoms. R ¹⁹ and R ²⁰ are independently alkyl groups having 1 to 5 carbon atoms, and R ²¹ and R ²² are independently aryl groups having 4 to 10 carbon atoms, respectively, and R 23 and R are R ²³ and R. At least one of the ²⁴ is an alkenyl group having 2 to 10 carbon atoms, and m1, m2 and m3 are independently integers of 1 or more.

The repeating unit having the structure of the above formula (40) includes a repeating unit substituted with an alkyl group, a siloxane repeating unit substituted with an aryl group, and a siloxane repeating unit substituted with an alkenyl group. In addition to improving the tensile elasticity of the resin layer, the adhesion between the resin layer and the glass substrate is improved, and the texture of the laminated body is also improved.

The order of the repeating unit substituted with the alkyl group, the siloxane repeating unit substituted with the aryl group, and the siloxane repeating unit substituted with the alkenyl group can be arbitrarily changed and may be arranged alternately.

In one embodiment of the present invention, in the structural unit represented by the above formula (40), R ¹⁷ and R ¹⁸ are independently single bonds, alkylene groups having 1 to 5 carbon atoms, or 6 or more carbon atoms, respectively. It is a divalent aromatic group of, preferably an alkylene group having 3 or more carbon atoms. Further, R3 and R4 are independently alkyl groups having 1 to 5 carbon atoms, preferably methyl or ethyl groups.
Further, R ¹⁹ and R ²⁰ are independently aryl groups having 4 to 10 carbon atoms, and are preferably phenyl groups.
Further, at least one of R ²¹ and R ²² is an alkenyl group having 2 to 10 carbon atoms, preferably an ethenyl or propenyl group. The other non-alkenyl group is an alkyl group having 1 to 5 carbon atoms.

Further, in one embodiment of the present invention, m1, m2 and m3 are independently integers of 1 to 10 in the structural unit represented by the above formula (40), and specifically, m1 is 3. ~ 9, m2 is an integer of 2 to 9, and m3 is an integer of 1 to 5.

In one embodiment of the present invention, the structural unit represented by the above formula (40) is 5 mol% or more or 50 mol% or less, preferably 50 mol% or less, with respect to the whole unit from the viewpoint of the balance between heat resistance and adhesion. It is 5 to 40 mol%.

The polyimide may contain a halogen atom such as a fluorine atom which can be introduced by, for example, the above-mentioned fluorine-containing substituent or the like. When the polyimide contains a halogen atom, it is easy to improve the tensile elastic modulus of the resin layer and reduce the YI value. Further, the tensile elastic modulus of the resin layer in the case of a single-layer film may be adjusted to a range of 1 to 15% with respect to the bending elastic modulus of the glass substrate alone, depending on the degree of substitution of halogen atoms. The halogen atom is preferably a fluorine atom. Preferred fluorine-containing substituents for containing a fluorine atom in polyimide include, for example, a fluoro group and a trifluoromethyl group.

The content of the halogen atom in the polyimide is preferably 1 to 40% by mass, more preferably 5 to 40% by mass, still more preferably 5 to 30% by mass, based on the mass of the polyimide. When the content of the halogen atom is at least the above lower limit, the elastic modulus of the resin layer is further improved, the yellowness is further reduced, and the transparency and visibility are more likely to be improved. When the content of the halogen atom is not more than the above upper limit, the resin can be easily synthesized.

The imidization ratio of the polyimide is preferably 90% or more, more preferably 93% or more, still more preferably 96% or more. From the viewpoint of easily increasing the optical homogeneity of the laminate, the imidization ratio is preferably at least the above lower limit. Further, the upper limit of the imidization rate is 100% or less. The imidization ratio indicates the ratio of the molar amount of the imide bond of the polyimide to the value of twice the molar amount of the structural unit derived from the tetracarboxylic acid compound in the polyimide. When the polyimide contains a tricarboxylic acid compound, the value is twice the molar amount of the structural unit derived from the tetracarboxylic acid compound in the polyimide and the molar amount of the structural unit derived from the tricarboxylic acid compound. , Percentage of molar amount of imide bond in polyimide. The imidization rate can be determined by an IR method, an NMR method, or the like.

The polyimide can be produced, for example, using a tetracarboxylic acid compound and a diamine compound as main raw materials. A diisocyanate compound may be used instead of the diamine compound.

Examples of the diamine compound used in the production of polyimide include aliphatic diamines, aromatic diamines and mixtures thereof. In addition, in this embodiment, "aromatic diamine" represents a diamine in which an amino group is directly bonded to an aromatic ring, and an aliphatic group or another substituent may be contained in a part of the structure thereof. The aromatic ring may be a monocyclic ring or a condensed ring, and examples thereof include, but are not limited to, a benzene ring, a naphthalene ring, an anthracene ring, and a fluorene ring. Among these, the benzene ring is preferable. Further, the "aliphatic diamine" represents a diamine in which an amino group is directly bonded to an aliphatic group, and an aromatic ring or other substituent may be contained as a part of the structure thereof.

Aliphatic diamines include, for example, acyclic aliphatic diamines such as hexamethylenediamine, 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, norbornanediamine and 4,4'. -Cycholic aliphatic diamines such as diaminodicyclohexylmethane can be mentioned. These can be used alone or in combination of two or more.

Examples of the aromatic diamine include p-phenylenediamine, m-phenylenediamine, 2,4-toluenediamine, m-xylylene diamine, p-xylylene diamine, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene and the like. , 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'- Diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4) -Aminophenoxy) benzene, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, 2,2-bis [4- (4-aminophenoxy) phenyl] Propane, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2'-dimethylbenzidine, 2,2'-bis (trifluoromethyl) -4,4'-diaminodiphenyl (with TFMB) (May be described), 4,4'-bis (4-aminophenoxy) biphenyl, 9,9-bis (4-aminophenyl) fluorene, 9,9-bis (4-amino-3-methylphenyl) fluorene. , 9,9-Bis (4-amino-3-chlorophenyl) fluorene, 9,9-bis (4-amino-3-fluorophenyl) fluorene and the like, and examples thereof include aromatic diamines having two or more aromatic rings. These can be used alone or in combination of two or more.

The aromatic diamine is preferably 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 3 , 3'-diaminodiphenyl sulfone, 1,4-bis (4-aminophenoxy) benzene, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, 2 , 2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2'-dimethylbenzidine, 2,2'-bis ( Trifluoromethyl) -4,4'-diaminodiphenyl (TFMB), 4,4'-bis (4-aminophenoxy) biphenyl, more preferably 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl. Propane, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 1,4-bis (4-aminophenoxy) benzene, bis [4- (4-aminophenoxy) phenyl] sulfone, 2,2- Bis [4- (4-aminophenoxy) phenyl] propane, 2,2'-dimethylbenzidine, 2,2'-bis (trifluoromethyl) -4,4'-diaminodiphenyl (TFMB), 4,4'- Biphenyl (4-aminophenoxy) biphenyl. These can be used alone or in combination of two or more.

Among the above diamine compounds, at least one selected from the group consisting of aromatic diamines having a biphenyl structure is selected from the viewpoints of surface hardness, transparency, flexibility, bending resistance and degree of coloring (YI value) of the laminate. It is preferable to use it. One selected from the group consisting of 2,2'-dimethylbenzidine, 2,2'-bis (trifluoromethyl) benzidine, 4,4'-bis (4-aminophenoxy) biphenyl and 4,4'-diaminodiphenyl ether. It is more preferable to use the above, and it is even more preferable to use 2,2'-bis (trifluoromethyl) -4,4'-diaminodiphenyl (TFMB).

Examples of the tetracarboxylic acid compound used for producing polyimide include aromatic tetracarboxylic acid compounds such as aromatic tetracarboxylic acid dianhydride and aliphatic tetracarboxylic acid compounds such as aliphatic tetracarboxylic acid dianhydride. Be done. The tetracarboxylic acid compound may be used alone or in combination of two or more. The tetracarboxylic acid compound may be a tetracarboxylic acid compound analog such as an acid chloride compound in addition to the dianhydride.

Specific examples of the aromatic tetracarboxylic acid dianhydride include a non-condensed polycyclic aromatic tetracarboxylic acid dianhydride, a monocyclic aromatic tetracarboxylic acid dianhydride, and a condensed polycyclic aromatic tetra. Examples include carboxylic acid dianhydride. Examples of the non-condensed polycyclic aromatic tetracarboxylic acid dianhydride include 4,4'-oxydiphthalic acid dianhydride, 3,3', 4,4'-benzophenone tetracarboxylic acid dianhydride, 2,2. ', 3,3'-benzophenone tetracarboxylic acid dianhydride, 3,3', 4,4'-biphenyltetracarboxylic acid dianhydride, 2,2', 3,3'-biphenyltetracarboxylic acid dianhydride , 3,3', 4,4'-diphenylsulfone tetracarboxylic acid dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (2,3-di) Carboxyphenyl) propane dianhydride, 2,2-bis (3,4-dicarboxyphenoxyphenyl) propane dianhydride, 4,4'-(hexafluoroisopropylidene) diphthalic acid dianhydride (abbreviated as 6FDA) There are), 1,2-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,2-bis (3,) 4-Dicarboxyphenyl) ethane dianhydride, 1,1-bis (3,4-dicarboxyphenyl) ethane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, bis (2,3) Examples thereof include -dicarboxyphenyl) methane dianhydride, 4,4'-(p-phenylenedioxy) diphthalic acid dianhydride, and 4,4'-(m-phenylenedioxy) diphthalic acid dianhydride. Examples of the monocyclic aromatic tetracarboxylic acid dianhydride include 1,2,4,5-benzenetetracarboxylic acid dianhydride, and the condensed polycyclic aromatic tetracarboxylic acid dianhydride. Examples thereof include 2,3,6,7-naphthalenetetracarboxylic acid dianhydride.

Among the above, preferably 4,4'-oxydiphthalic acid dianhydride, 3,3', 4,4'-benzophenone tetracarboxylic dianhydride, 2,2', 3,3'-benzophenone tetracarboxylic dianhydride. Anhydride, 3,3', 4,4'-biphenyltetracarboxylic acid dianhydride, 2,2', 3,3'-biphenyltetracarboxylic acid dianhydride, 3,3', 4,4'-diphenyl Sulfontetracarboxylic acid dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, 2,2- Bis (3,4-dicarboxyphenoxyphenyl) propane dianhydride, 4,4'-(hexafluoroisopropylidene) diphthalic acid dianhydride (6FDA), 1,2-bis (2,3-dicarboxyphenyl) Etan dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,2-bis (3,4-dicarboxyphenyl) ethane dianhydride, 1,1-bis (3) , 4-Dicarboxyphenyl) ethane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, 4,4'-(p-) Examples thereof include phenylenedioxy) diphthalic acid dianhydride and 4,4'-(m-phenylenedioxy) diphthalic acid dianhydride, more preferably 4,4'-oxydiphthalic acid dianhydride, 3,3',. 4,4'-biphenyltetracarboxylic acid dianhydride, 2,2', 3,3'-biphenyltetracarboxylic acid dianhydride, 4,4'-(hexafluoroisopropylidene) diphthalic acid dianhydride (6FDA) , Bis (3,4-dicarboxyphenyl) methane dianhydride and 4,4'-(p-phenylenedioxy) diphthalic acid dianhydride. These can be used alone or in combination of two or more.

Examples of the aliphatic tetracarboxylic dianhydride include cyclic or acyclic aliphatic tetracarboxylic dianhydride. The cyclic aliphatic tetracarboxylic acid dianhydride is a tetracarboxylic acid dianhydride having an alicyclic hydrocarbon structure, and specific examples thereof include 1,2,4,5-cyclohexanetetracarboxylic acid dianhydride. , 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, cycloalkhantetracarboxylic acid dianhydride such as 1,2,3,4-cyclopentanetetracarboxylic acid dianhydride, Bicyclo [2.2] .2] Oct-7-ene-2,3,5,6-tetracarboxylic acid dianhydride, dicyclohexyl3,3'-4,4'-tetracarboxylic acid dianhydride and their positional isomers can be mentioned. .. These can be used alone or in combination of two or more. Specific examples of the acyclic aliphatic tetracarboxylic dianhydride include 1,2,3,4-butanetetracarboxylic dianhydride, 1,2,3,4-pentanetetracarboxylic dianhydride and the like. These can be used alone or in combination of two or more. Further, a cyclic aliphatic tetracarboxylic dianhydride and an acyclic aliphatic tetracarboxylic dianhydride may be used in combination.

Among the tetracarboxylic acid dianhydrides, 4,4'-oxydiphthalic acid dianhydride, 3 from the viewpoint of high surface hardness, high transparency, high flexibility, high bending resistance, and low coloring property of the optical film. , 3', 4,4'-benzophenone tetracarboxylic acid dianhydride, 3,3', 4,4'-biphenyltetracarboxylic acid dianhydride, 2,2', 3,3'-biphenyltetracarboxylic acid dian Anhydrous, 3,3', 4,4'-diphenylsulfonetetracarboxylic acid dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 4,4'-(hexafluoroisopropi) Liden) diphthalic acid dianhydride, as well as mixtures thereof, are preferred, 3,3', 4,4'-biphenyltetracarboxylic acid dianhydride and 4,4'-(hexafluoroisopropyridene) diphthalic acid dianhydride, In addition, a mixture thereof is more preferable, and 4,4'-(hexafluoroisopropyridene) diphthalic acid dianhydride (6FDA) is further preferable.

As the dicarboxylic acid compound used for producing the polyimide, terephthalic acid, 4,4'-oxybis benzoic acid or an acid chloride compound thereof is preferably used. In addition to terephthalic acid, 4,4'-oxybis benzoic acid or their acid chloride compounds, other dicarboxylic acid compounds may be used. Examples of other dicarboxylic acid compounds include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, acid chloride compounds related thereto, acid anhydrides, and the like, and two or more of them may be used in combination.
Specific examples include a dicarboxylic acid compound of isophthalic acid; naphthalenedicarboxylic acid; 4,4'-biphenyldicarboxylic acid; 3,3'-biphenyldicarboxylic acid; a chain hydrocarbon having 8 or less carbon atoms, and two benzoic acids. Can be mentioned as a single bond, -CH _2- , -C (CH ₃ ) _2- , -C (CF ₃ ) _2- , -SO _2- or a compound linked with a phenylene group, and their acid chloride compounds. .. As specific examples, 4,4'-oxybis (benzoyl chloride) and terephthaloyl chloride are preferable, and 4,4'-oxybis (benzoyl chloride) and terephthaloyl chloride are more preferably used in combination.

The polyimide may be obtained by further reacting a tetracarboxylic acid and a tricarboxylic acid and their anhydrides and derivatives in addition to the tetracarboxylic acid compound as long as the various physical properties of the laminate are not impaired. Examples of the tetracarboxylic acid include water adducts of the anhydride of the tetracarboxylic acid compound. Examples of the tricarboxylic acid compound include aromatic tricarboxylic acids, aliphatic tricarboxylic acids, acid chloride compounds related thereto, acid anhydrides, and the like, and two or more of them may be used in combination. Specific examples include anhydrate of 1,2,4-benzenetricarboxylic acid; 2,3,6-naphthalentricarboxylic acid-2,3-anhydride; a single bond of phthalic anhydride and benzoic acid, -O-. , -CH _2- , -C (CH ₃ ) _2- , -C (CF ₃ ) _2- , -SO _2- or compounds linked with a phenylene group.

In the production of the polyimide, the amount of the diamine compound, the tetracarboxylic acid compound and / or the dicarboxylic acid compound to be used can be appropriately selected according to the ratio of each structural unit of the desired polyimide.

In the production of polyimide, the reaction temperature of the diamine compound, the tetracarboxylic acid compound and the dicarboxylic acid compound is not particularly limited, but is, for example, 5 to 350 ° C., preferably 20 to 200 ° C., and more preferably 25 to 100 ° C. The reaction time is also not particularly limited, but is, for example, about 30 minutes to 10 hours. If necessary, the reaction may be carried out under conditions of an inert atmosphere or reduced pressure. In a preferred embodiment, the reaction is carried out under normal pressure and / or under an inert gas atmosphere with stirring. The reaction is preferably carried out in a solvent inert to the reaction.

The solvent is not particularly limited as long as it does not affect the reaction, and is, for example, water, methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, 1-methoxy-2-propanol, and the like. Alcohol-based solvents such as 2-butoxyethanol and propylene glycol monomethyl ether; ester-based solvents such as ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone, γ-valerolactone, propylene glycol methyl ether acetate and ethyl lactate; Ketone-based solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-heptanone, and methylisobutylketone; aliphatic hydrocarbon solvents such as pentane, hexane, and heptane; alicyclic hydrocarbon solvents such as ethylcyclohexane; toluene, xylene Aromatic hydrocarbon solvents such as; nitrile solvents such as acetonitrile; ether solvents such as tetrahydrofuran and dimethoxyethane; chlorine-containing solvents such as chloroform and chlorobenzene; amides such as N, N-dimethylacetamide and N, N-dimethylformamide. Examples thereof include sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide, and sulfolane; carbonate solvents such as ethylene carbonate and propylene carbonate; and combinations thereof (mixed solvents). Among these, an amide-based solvent can be preferably used from the viewpoint of solubility.

In the imidization step in the production of polyimide, imidization can be performed in the presence of an imidization catalyst. Examples of imidization catalysts include aliphatic amines such as tripropylamine, dibutylpropylamine and ethyldibutylamine; N-ethylpiperidine, N-propylpiperidine, N-butylpyridine, N-butylpiperidine, and N-propylhexahydro. Alicyclic amines such as azepine (monocyclic); azabicyclo [2.2.1] heptane, azabicyclo [3.2.1] octane, azabicyclo [2.2.2] octane, and azabicyclo [3.2. 2] Alicyclic amines such as nonane (polycyclic); as well as pyridine, 2-methylpyridine (2-picolin), 3-methylpyridine (3-picolin), 4-methylpyridine (4-picolin), 2- Ethylpyridine, 3-ethylpyridine, 4-ethylpyridine, 2,4-dimethylpyridine, 2,4,6-trimethylpyridine, 3,4-cyclopentenopyridine, 5,6,7,8-tetrahydroisoquinoline, and Examples include aromatic amines such as isoquinolin.

Further, from the viewpoint of facilitating the imidization reaction, it is preferable to use an acid anhydride together with the imidization catalyst. Examples of the acid anhydride include conventional acid anhydrides used in the imidization reaction, and specific examples thereof include acetic anhydride, propionic anhydride, aliphatic acid anhydrides such as butyric anhydride, and aromatics such as phthalic acid. Acid anhydride and the like can be mentioned.

The polyimide may be isolated (separated and purified) by a conventional method, for example, a separation means such as filtration, concentration, extraction, crystallization, recrystallization, column chromatography, or a separation means combining these, which is a preferred embodiment. Then, it can be isolated by adding a large amount of alcohol such as methanol to the reaction solution containing the transparent polyamideimide resin, precipitating the resin, and performing concentration, filtration, drying and the like.

As the polyimide as described above, a commercially available polyimide may be used, for example, Aurum PL450C (Mitsui Chemicals, Inc.), KPI-MX400F (Kawamura Sangyo Co., Ltd.), SPIXREA (registered trademark) GR003 (Somar Corporation), SPIXREA. (Registered trademark) GR004 (Somar Corporation), KOLON polyimide (KOLON Corporation), SMP-7015-3S (Shin-Etsu Chemical Co., Ltd.) and the like can be mentioned.

As a method of forming a resin layer so as to be in contact with one of the main surfaces of the glass substrate, for example, a varnish containing a polyimide precursor polyamic acid is applied to the surface of the glass substrate to form a coating film, and then the coating film is formed. The coating film may be heated to imidize the polyimide precursor, or a polyimide varnish in which polyimide is dissolved in a solvent is prepared, and the polyimide varnish is applied to the surface of a glass substrate to form a coating film, and then the coating film is formed. The resin layer may be formed by drying the varnish to remove the solvent.

<Functional layer>
The functional layer provided on the above-mentioned resin layer as desired will be described. The functions of the functional layer are not particularly limited, and are hard coat function, antistatic function, antiglare function, low reflection function, antireflection function, antifouling function, gas barrier function, primer function, electromagnetic wave shielding function, undercoat function, and ultraviolet absorption. It may be a general function adopted for the cover glass of the flexible display element, such as a function, an adhesive function, and a hue adjustment function. The functional layer may be a layer having one kind of function, or may be a layer having two or more kinds of functions. From the viewpoint of ease of use as a cover glass, at least one of the functional layers is selected from the group consisting of a hard coat function, an antistatic function, an antiglare function, a low reflection function, an antireflection function and an antifouling function. It is preferably a layer having one function. As the functional layer, one layer may have a plurality of functions, or two or more layers having each function may be laminated. When two or more layers are laminated, the order of stacking is appropriately set according to the function.

The thickness of the functional layer may be appropriately set according to the desired function, but is preferably 20 μm or less, more preferably 15 μm or less, and further, from the viewpoint of easily increasing the weight reduction and optical homogeneity of the laminate. It is preferably 10 μm or less.

(Hard coat function)
The hard coat function is a function of imparting scratch resistance, chemical resistance, etc. to the surface of the optical film to protect the optical film. In the optical laminate of the present invention, the functional layer may be a layer having a hard coat function (hard coat layer). As the hard coat layer, a known hard coat layer may be appropriately adopted, and examples thereof include known hard coat layers such as acrylic type, epoxy type, urethane type, benzyl chloride type, and vinyl type. Among these, acrylic, urethane, and hard coat layers in combination thereof are preferable from the viewpoint of suppressing deterioration of visibility in the wide angle direction of the optical laminate and improving bending resistance. For example, the hardcourt layer may be a cured product of a composition containing an active energy ray-curable compound. The active energy ray-curable compound is a compound having a property of being cured by irradiating with an active energy ray such as an electron beam or ultraviolet rays. Examples of such an active energy ray-curable compound include an electron beam-curable compound that is cured by irradiating with an electron beam and an ultraviolet-curable compound that is cured by irradiating with ultraviolet rays. These compounds are the same compounds as the main components of the hard coat agent used for forming a normal hard coat layer, and examples thereof include (meth) acrylic resins. In particular, among the (meth) acrylic resins, those containing a polyfunctional (meth) acrylate compound as a main component are preferable. In addition, in this specification, (meth) acrylic means acrylic and / or methacrylic, and (meth) acrylate means acrylate and / or methacrylate.

The polyfunctional (meth) acrylate compound is a compound having at least two acryloyloxy groups and / or a methacryloyloxy group in the molecule, and specifically, ethylene glycol di (meth) acrylate and diethylene glycol di (meth). ) Acryloyl, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethanetri (meth) acrylate, tetramethylolmethanetri (meth) acrylate , Tetramethylolmethane Tetra (meth) acrylate, pentaglycerol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, glycerintri (meth) acrylate, dipentaerythritol tri (meth) acrylate, Dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, trics ((meth) acryloyloxyethyl) isocyanurate, (meth) acryloyloxy on the phosphazene ring of the phosphazenic compound. Obtained by reaction of a phosphazenic acrylate compound or a phosphazenic methacrylate compound into which a group has been introduced, a polyisocyanate having at least two isocyanate groups in the molecule, and a polyol compound having at least one (meth) acryloyloxy group and a hydroxyl group. Urethane (meth) acrylate compound, polyester (meth) acrylate compound obtained by reaction of at least two carboxylic acid halides in the molecule with a polyol compound having at least one (meth) acryloyloxy group and a hydroxyl group, and Examples thereof include oligomers such as dimer and trimer of each of the above compounds.

These compounds may be used alone or in admixture of two or more. In addition to the above polyfunctional (meth) acrylate compound, at least one monofunctional (meth) acrylate may be used. Examples of the monofunctional (meth) acrylate include hydroxyethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, and 2-hydroxy-3-phenoxypropyl. Examples thereof include (meth) acrylate and glycidyl (meth) acrylate. These compounds may be used alone or in admixture of two or more. The content of the monofunctional (meth) acrylate compound is preferably 10% by mass or less with respect to the solid content of the compound contained in the composition for forming a functional layer (paint for a hard coat layer). In addition, in this specification, a solid content means all components except a solvent contained in a curable composition.

A polymerizable oligomer may be added to the functional layer, for example, for the purpose of adjusting the hardness. Examples of such oligomers include terminal (meth) acrylate polymethylmethacrylate, terminal styrylpoly (meth) acrylate, terminal (meth) acrylate polystyrene, terminal (meth) acrylate polyethylene glycol, terminal (meth) acrylate acrylonitrile-styrene copolymer, and the like. Macromonomers such as terminal (meth) acrylate styrene-methyl (meth) acrylate copolymers can be mentioned. When the polymerizable oligomer is added, the content thereof is preferably 5 to 50% by mass with respect to the solid content of the composition for forming a functional layer.

The active energy ray-curable compound may be used in the state of a solution mixed with a solvent. The active energy ray-curable compound or a solution thereof may be commercially available as a hard coat agent. Specific examples of commercially available hard coat agents include NK Hard M101 (urethane acrylate compound, Shin-Nakamura Chemical Co., Ltd.), NK Ester A-TMM-3L (tetramethylol methanetriacrylate, Shin-Nakamura Chemical Co., Ltd.), NK. Ester A-9530 (Dipentaerythritol hexaacrylate, Shin-Nakamura Chemical Co., Ltd.), KAYARAD (registered trademark) DPCA series (derivative of dipentaerythritol hexaacrylate compound, Nippon Kayaku Co., Ltd.), Aronix (registered trademark) M-8560 (Polyester acrylate compound, Toa Synthetic Co., Ltd.), New Frontier (registered trademark) TEICA (Tris (acryloyloxyethyl) isocyanurate, Daiichi Kogyo Seiyaku Co., Ltd.), PPZ (phosphazenic methacrylate compound, Kyoeisha Chemical Co., Ltd.), etc. Illustrated.

When ultraviolet rays or visible light are used as the active energy rays, a photopolymerization initiator is usually used as the polymerization initiator. Examples of the photopolymerization initiator include acetophenone, acetophenone benzyl ketal, anthraquinone, 1- (4-isopropylphenyl-2-hydroxy-2-methylpropan-1-one, carbazole, xanthone, 4-chlorobenzophenone, 4, 4'-diaminobenzophenone, 1,1-dimethoxydeoxybenzoin, 3,3'-dimethyl-4-methoxybenzophenone, thioxanthone, 2,2-dimethoxy-2-phenylacetophenone, 1- (4-dodecylphenyl) -2- Hydroxy-2-methylpropan-1-one, 2-methyl-1- [4- (methylthio) phenyl] -2-morphorinopropane-1-one, triphenylamine, 2,4,6-trimethylbenzoyldiphenyl Phosphine oxide, 1-hydroxycyclohexylphenylketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, fluorenone, fluorene, benzaldehyde, benzoin ethyl ether, benzoisopropyl ether, benzophenone, Michler ketone, 3-methylacetophenone, 3,3', 4,4'-tetratert-butylperoxycarbonylbenzophenylone (BTTB), 2- (dimethylamino) -1- [4- (morpholinyl) phenyl] -2-phenylmethyl) -1- Butanone, 4-benzoyl-4'-methyldiphenylsulfide, benzyl and the like can be mentioned.

Further, the photopolymerization initiator may be used in combination with a dye sensitizer. Examples of the dye sensitizer include xanthene, thioxanthene, coumarin, ketocoumarin and the like. Examples of the combination of the photopolymerization initiator and the dye sensitizer include a combination of BTTB and xanthene, a combination of BTTB and thioxanthene, a combination of BTTB and coumarin, and a combination of BTTB and ketocoumarin.

When a photopolymerization initiator is used, the amount used is preferably 0.1 part by mass or more with respect to 100 parts by mass of the active energy ray-curable compound. When the amount used is in the above range, it tends to be easy to obtain a sufficient curing rate. The amount of the photopolymerization initiator used is preferably 10 parts by mass or less per 100 parts by mass of the active energy ray-curable compound.

The thickness of the hard coat layer can be appropriately set, but from the viewpoint of bending resistance, surface hardness and optical homogeneity of the laminated body, it is preferably 20 μm or less, more preferably 15 μm or less, still more preferably 10 μm or less. Is.

As a method of forming the hard coat layer on the surface of the resin layer, for example, a composition for forming a hard coat layer containing an active energy ray-curable compound (active energy ray-curable resin) is applied to the surface of the resin layer and activated. All you have to do is irradiate the energy rays. Such a composition can be obtained by mixing an active energy ray-curable compound with an additive or the like, if necessary. The cured product of the composition for forming the hard coat layer constitutes the hard coat layer.

The composition for forming a hard coat layer preferably contains a solvent, and it is preferable that the active energy ray-curable compound is diluted with a solvent in the composition for forming a hard coat layer. In this case, the composition is produced by mixing an active energy ray-curable compound and various additives for imparting surface smoothness (for example, silicone oil, etc.), and then diluting the obtained mixture with a solvent. Alternatively, the active energy ray-curable compound may be diluted with a solvent and then mixed with an additive to produce the compound, or the active energy ray-curable compound may be mixed with an additive diluted with a solvent in advance. It may be produced, or it may be produced by mixing an active energy ray-curable compound diluted with a solvent in advance and an additive diluted with a solvent in advance. The composition after mixing may be further stirred.

From the viewpoint of facilitating coating, it is preferable that the composition for forming a hard coat layer contains an appropriate solvent. Solvents include aliphatic hydrocarbons such as hexane and octane, aromatic hydrocarbons such as toluene and xylene, alcohols such as ethanol, 1-propanol, isopropanol and 1-butanol, and ketones such as methyl ethyl ketone and methyl isobutyl ketone. Esters such as ethyl acetate and butyl acetate, cellosolves and the like can be appropriately selected and used. Several kinds of these organic solvents may be mixed and used as needed. The boiling point of the solvent is preferably in the range of 70 ° C. to 200 ° C. from the viewpoint that the composition for forming a hard coat layer is easily heated after coating to evaporate the organic solvent. The type and amount of the solvent are appropriately selected according to the type and amount of the active energy ray-curable compound to be used, the material and shape of the resin layer, the coating method, the thickness of the target hard coat layer, and the like.

(Anti-static function)
The antistatic function is a function of preventing the surface of the laminated body from being charged. In the laminated body of the present invention, the functional layer may be a layer having an antistatic function (antistatic layer). As a method for forming the antistatic layer, in addition to the method of adding an antistatic agent to the composition for forming a hard coat layer to impart an antistatic function to the hard coat layer, the antistatic agent is diluted with a solvent or the like. Examples thereof include a method in which the obtained antistatic layer forming composition is applied onto a hard coat layer formed on the surface of a resin layer, and if necessary, dried to form a single film. The antistatic agent may be contained as a structural unit having an antistatic function in a part of a resin constituting the functional layer (for example, a cured product of the above-mentioned active energy ray-curable compound), or form the functional layer. It may be added as an additive in the resin to be used. When the antistatic agent is added as an additive, the amount of the antistatic agent added is preferably 0.01 to 20% by mass, more preferably 0.05 to 10% by mass, based on the solid content of the composition for forming a functional layer. %, More preferably 0.1 to 10% by mass.

(Anti-glare function)
The anti-glare function is a function to prevent reflection of external light by scattering and reflecting light. In the laminated body of the present invention, the functional layer may be a layer having an antiglare function (antiglare layer). As the antiglare layer, a known one can be appropriately adopted. For example, an antiglare function may be imparted by forming a layer having a fine uneven shape on the surface by using a resin composition containing one or more kinds of translucent fine particles in the translucent resin. More specifically, for such an antiglare layer, for example, a translucent resin solution in which translucent fine particles as a filler are dispersed is applied to the surface of the resin layer, and the translucent fine particles are the surface of the antiglare layer. It can be formed by adjusting the thickness of the coating so as to be a convex portion in. In addition, in this specification, "translucency" means that light can be substantially transmitted regardless of the presence or absence of scattering inside a substance.

(Anti-reflection function and low reflection function)
The antireflection function and the low reflection function are functions for preventing or reducing the reflection of external light. In the laminated body of the present invention, the functional layer may be a layer having a function of preventing reflection of external light (antireflection layer), or a layer having a function of reducing reflection of external light (low reflection layer). You may. The antireflection layer and the low reflection layer may be a single layer or a multilayer.

The antireflection layer may include a low refractive index layer. Further, the antireflection layer may be a layer having a multilayer structure further including a low refractive index layer, a high refractive index layer and / or a medium refractive index layer laminated between the low refractive index layer and the resin layer. good. The above-mentioned hard coat layer may be provided between the antireflection layer and the resin layer.

The thickness of the antireflection layer is preferably 0.01 to 1 μm, more preferably 0.02 to 0.5 μm. The antireflection layer is composed of a low refractive index layer having a refractive index smaller than the refractive index of the resin layer provided with the antireflection layer or another functional layer (for example, a refractive index of 1.3 to 1.45), or an inorganic compound. Examples thereof include a layer in which a plurality of low refractive index layers of a thin film and a high refractive index layer of a thin film made of an inorganic compound are alternately laminated. Here, the refractive index of the high refractive index layer may be larger than the refractive index of the low refractive index layer, but is preferably 1.60 or more.

The material forming the low refractive index layer is not particularly limited as long as it is a material having a low refractive index. For example, a resin material such as an active energy ray-curable resin (for example, an ultraviolet curable acrylic resin), a hybrid material in which inorganic fine particles such as colloidal silica are dispersed in the resin, and a sol-gel using a metal alkoxide such as tetraethoxysilane. Materials and the like can be mentioned. The material forming these low refractive index layers may be a polymerized polymer, or may be a monomer or an oligomer as a precursor. Further, the material constituting the antireflection layer preferably contains a compound containing fluorine because the antireflection function can be imparted to the antireflection layer.

The high refractive index layer is formed by applying a coating liquid containing a cured product of the above-mentioned active energy ray-curable resin, a translucent resin such as a metal alkoxide polymer, and inorganic fine particles and / or organic fine particles, and then a coating film. Can be formed by curing as needed. Examples of the inorganic fine particles include zinc oxide, titanium oxide, cerium oxide, aluminum oxide, silane oxide, tantalum oxide, yttrium oxide, ytterbium oxide, zirconium oxide, antimony oxide, and indium tin oxide (ITO). The high refractive index layer containing these inorganic fine particles may also have an antistatic function.

The low-reflection layer is a layer made of a low-refractive index material having a lower refractive index than a resin layer or, if desired, another functional layer. The low refractive index layer is coated with a coating liquid containing a cured product of the above-mentioned active energy ray-curable resin, a translucent resin such as a metal alkoxide polymer, and inorganic fine particles, and then the coating film is cured as necessary. It can be formed by letting it. Specific examples of such a low refractive index material include lithium fluoride (LiF), magnesium fluoride (MgF ₂ ), aluminum fluoride (AlF ₃ ), and glacial stone (3NaF / AlF ₃ or Na ₃ AlF ₆ ). ) And other inorganic material fine particles are contained in acrylic resin, epoxy resin, etc. Inorganic low-reflection material; fluorine-based or silicone-based organic compound, thermoplastic resin, thermocurable resin, ultraviolet curable resin, etc. Examples include organic low-reflection materials.

<Touch sensor function>
By forming the transparent electrode layer on the surface of the resin layer, the touch sensor function can be imparted to the laminated body. It can be obtained, for example, by forming a transparent electrode layer on the surface of the resin layer or another functional layer provided as desired by a sputtering apparatus. This makes it possible to obtain a touch panel such as a transparent electrode when the laminate of the present invention is used for the cover glass.

<Support>
By providing the support, the mechanical strength of the laminated body can be improved. Any material having light transmission, mechanical strength, and flexibility can be used without particular limitation. For example, polyimide, polyethylene terephthalate, polycarbonate, polyethersulfone, polyetheretherketone, polyvinylfluorofluoride, polyacrylate, polypropylene, polyethylene, etc. A transparent resin sheet such as amorphous polyolefin or fluororesin can be preferably used.

The thickness of the support may be appropriately determined depending on the intended use of the laminate. For example, when the laminate is used as the cover glass of the flexible display element, it is preferably 40 to 200 μm, more preferably 50 to 50. It is 100 μm.

<Use of laminated body>
A flexible display element can be manufactured using the laminate of the present invention. Examples of the flexible display element include an organic EL display, for example, a bottom emission type flexible organic EL display, a top emission type flexible organic EL display, and the like; or a flexible liquid crystal display. When the laminate of the present embodiment is used as the cover glass of the flexible display element, the flexible display element includes a light source so that the light of this light source passes through the laminate of the present embodiment and is output to the outside of the flexible display element. It is preferable to be configured in. When the laminate of the present embodiment is used as the cover glass of the flexible display element, the laminate is arranged so that the glass substrate is arranged on the light source side of the resin layer.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the Examples. In the following, "part" and "%" are all based on mass unless otherwise specified.

<Preparation of glass substrate>
As the glass substrate, the following three types of glass substrates 1 to 3 were prepared.
-Glass substrate 1: SHOTT AS87 eco (manufactured by SHOTT, thickness 50 μm, 80 μm, flexural modulus 73 GPa)
-Glass substrate 2: Dragontrail (registered trademark) (manufactured by AGC Inc., thickness 80 μm, flexural modulus 82 GPa)
-Glass substrate 3: G-Leaf (registered trademark) OA-10G (manufactured by Nippon Electric Glass Co., Ltd., thickness 50 μm, flexural modulus 73 GPa)

For the flexural modulus, a test piece (width 10 mm, length 60 mm) is cut out using a glass cutter, and the test piece is a three-point bending jig (BT-5000N, manufactured by Imada Co., Ltd., indenter R = 3 mm, support. Using a universal testing machine (electric measuring stand MX2-5000N, manufactured by Imada Co., Ltd.) equipped with R = 3 mm, distance between supports = 25 mm, measurement is performed under the conditions of crosshead speed 0.5 mm / min and 25 ° C. went.

<Preparation of resin layer forming material>
The following five types of resins 1 to 5 were prepared as the resin layer.
-Resin 1: Aurum (registered trademark) PL450C (polyimide, Mitsui Chemicals, Inc., thickness 5 μm, 15 μm, 25 μm, tensile modulus 2 GPa)
Resin 2: SPIXREA (registered trademark) GR003 (polyimide, Somar Corporation, thickness 25 μm, tensile modulus 5 GPa)
-Resin 3: KOLON (polyamideimide, KOLON, thickness 25 μm, tensile modulus 6 GPa)
Resin 4: Optiria (registered trademark) (polyacrylate, Lintec Corporation, thickness 20 μm, tensile modulus 0.01 GPa)
-Resin 5: Iupizeta (registered trademark) (polycarbonate, Mitsubishi Gas Chemical Company, Inc., thickness 20 μm, tensile modulus 5 GPa)

[Examples 1 to 6, Comparative Examples 1 to 3]
Each glass substrate was placed on a support (soda glass plate having a thickness of 2 mm, a width of 150 mm, and a length of 200 mm), and the four corners were fixed with Kapton (registered trademark) tape. A tabletop coater (AFA-Standard, manufactured by Cortec Co., Ltd.) is placed on the surface of the glass substrate with a varnish in which each resin layer forming material is dissolved in dimethylacetamide so that the thickness of the resin layer after drying is as shown in Table 1 below. It was applied at a coating rate of 1 cm / min.
Next, the soda glass plate was placed in a blower dryer (DKM300, manufactured by Yamato Kagaku Co., Ltd.) at 80 ° C. and dried for 30 minutes. Then, the temperature was raised and the mixture was dried at 150 ° C. for 1 hour.
After drying, the soda glass plate was taken out from the blower type dryer, the Kapton (registered trademark) tape was removed, and the laminated body was obtained by peeling from the soda glass plate.
The combinations of the glass substrate and the resin layer forming material are as shown in Table 1 below.

<Measurement of tensile modulus>
A test piece (width 10 mm, length 60 mm) of the resin layer single film was cut out from the laminate using a cutter knife. The test piece was stretched using a tabletop tensile tester (EZ-SX, manufactured by Shimadzu Corporation) under the conditions of a gripping tool distance of 20 mm, a tensile speed of 10% strain / sec, and 25 ° C. The tensile modulus of the test piece was determined from the displacement of the stress with a strain of 0.2% to 0.5%. The tensile elastic modulus of the test piece (resin layer single layer film) is as shown in Table 1 below.

<Crosscut peeling test evaluation>
The obtained laminate was evaluated by a cross-cut peeling test according to ASTM D 3559-B. The evaluation results are as shown in Table 1 below.

<Flexibility evaluation>
A test piece (width 30 mm, length 100 mm) is cut out from the laminate using a diamond cutter, and the test piece is bent at a bending angle of 180 °, a load of 0.25 kgf, and a bending clamp R = using a MIT folding fatigue tester. The bending test was carried out 10 times under the conditions of 40 mm and 25 ° C.
If the test piece was not damaged, the bending clamp was changed to R20 mm, and the bending test was performed 10 times.
If the test piece was not damaged, the bending clamp was changed to R15 mm, and the bending test was performed 10 times.
Flexibility was evaluated according to the following evaluation criteria. The evaluation results are as shown in Table 1 below.
⊚: R15 mm or more ○: R20 mm or less, R15 mm or more Δ: R40 mm or less, R20 mm or more ×: R40 mm or more

<Evaluation of surface hardness>
A test piece was cut out from the laminate in the same manner as above, and a load was applied to the test piece at a pressurizing rate of 0.5 mN / 5 seconds using an ultrafine hardness tester and a Vickers indenter. After that, the Martens hardness was measured by holding the load of 0.5 mN for 5 seconds. The surface hardness was evaluated according to the following evaluation criteria. The evaluation results are as shown in Table 1 below. The Martens hardness of the glass substrate 1 alone was measured in the same manner and found to be 2900 N / mm ² .
◎ ◎: 500N / mm ² or more ◎: 300N / mm ² or more, less than 500N / mm ² ○: 100N / mm ² or more, less than 300N / mm ² Δ: 50N / mm ² or more, less than 100N / mm ² ×: 50N Less than / mm ²

<Flatness evaluation>
In the above-mentioned bending resistance test, the test piece bent 10 times under the condition of R40 mm is left standing in a state where it is not folded so that the folded inner surface faces the upper surface, and whether the bent portion is deformed (dented). Was visually observed and evaluated according to the following evaluation criteria. The evaluation results are as shown in Table 1 below.
○: No dent ×: With dent XX: With crack

1: Laminated body 10: Glass substrate 20: Resin layer 30: Functional layer 40: Support

Claims (6)

A laminate comprising a glass substrate and a resin layer provided on one of the main surfaces of the glass substrate so as to be in contact with the surface.
The resin layer contains a polymer having an imide structure and comprises.
When the resin layer is a single-layer film, the tensile elastic modulus is 1 to 15% with respect to the flexural modulus of the glass substrate alone.
The thickness of the glass substrate is 25 to 100 μm, and the thickness of the glass substrate is 25 to 100 μm.
The resin layer has a thickness of 6 to 100% with respect to the thickness of the glass substrate.
A laminate, characterized in that the adhesion between the glass substrate and the resin layer is 2B or more in the cross-cut peeling test evaluation according to ASTM D 3559-B. The laminate according to claim 1, wherein the glass substrate alone has a flexural modulus of 50 to 150 GPa. The laminate according to claim 1 or 2, wherein the tensile elastic modulus of the entire laminate is 5 GPa or more, or the flexural modulus is 10 GPa or more. The laminate according to any one of claims 1 to 3, wherein the total thickness of the glass substrate and the resin layer is 30 to 135 μm. The laminate according to any one of claims 1 to 4, wherein the glass substrate is chemically tempered glass. The laminate according to any one of claims 1 to 5, which is used as a cover glass for a flexible display element.

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