JP6248471B2 - Transparent laminated film and transparent substrate - Google Patents

Description

  The present invention relates to a transparent laminated film that can be used as a substrate material for solar cells, organic solar cells, flexible displays, organic EL lighting, touch panels, and the like, and a transparent substrate using the transparent laminated film.

  Conventionally, glass materials have been used as various display elements such as organic EL and substrate materials for solar cells. However, the glass material has not only the drawbacks of being easily broken, heavy, and difficult to reduce the thickness, but it has not been a sufficient material for reducing the thickness and weight of the display in recent years and making the display flexible. Therefore, a thin and lightweight transparent resin-made film-like substrate has been studied as an alternative material to replace glass.

As this type of transparent resin film-like substrate, for example, a conductive material having a structure in which a transparent conductive film made of a metal oxide such as ITO (indium tin oxide) is formed on a transparent resin film. Film is known.
By the way, in such a conductive film, since the transparent conductive film is usually formed by sputtering at room temperature, the amorphous property becomes high, and as a result, a transparent conductive film such as an ITO film is formed on the glass substrate. Compared to those, there was a problem that the surface resistance value, durability, acid resistance and the like were remarkably inferior. Therefore, in the electroconductive film provided with the transparent conductive film which consists of a metal oxide on a transparent resin film, raising the crystallinity of a transparent conductive film was one of the solution subjects.

  As a means for improving the crystallinity of a transparent conductive film such as an ITO film, for example, in Patent Document 1, after forming an ITO film on a polymer film substrate, heat treatment is performed to crystallize the ITO. Patent Document 2 discloses a crystallization method by irradiating an ITO film with microwaves.

  Patent Document 3 discloses a transparent laminated film having cured layers on both the front and back sides of a base film as a transparent film that can be used for a transparent substrate. This transparent laminated film has the property of being excellent in transparency and thermal dimensionality at high temperatures, and can be used as a substrate for solar cells, organic solar cells, flexible displays, organic EL lighting, touch panels and the like.

  In addition, Patent Document 4 relates to a conductive film, is excellent in input durability, prevents the occurrence of interference on the display, and prevents the occurrence of sticking and Newton rings on at least one surface of the transparent substrate film, A resin layer is formed directly or through another layer with a paint containing at least a resin and fine particles having an average particle diameter of 1 to 500 nm (and may further contain particles having an average particle diameter of 0.6 to 20 μm), A transparent conductive film in which a transparent conductive layer is provided on a resin layer directly or via another layer is disclosed.

Japanese Patent Laid-Open No. 2-194943 JP 2005-141981 International Publication No. 13/022011 Pamphlet JP 2000-94592 A

  In order to reduce the surface resistance value of the transparent conductive film made of ITO or the like, as described above, it is necessary to increase the crystallinity of the transparent conductive film, and as a means for that purpose, by forming the transparent conductive film at a high temperature A means for improving the crystallinity of the transparent conductive film can be considered. For example, if the formation of the transparent conductive film by sputtering, which is usually performed at room temperature, can be formed by sputtering in a high temperature atmosphere, for example, a temperature atmosphere of 150 to 220 ° C., the crystallinity of the transparent conductive film is increased. be able to.

However, a biaxially stretched PET film or the like that is generally used as a base film is thermally shrunk under such a high temperature atmosphere, so that a transparent conductive film cannot be formed under a high temperature atmosphere. I had a problem. On the other hand, if an entirely new material having excellent thermal dimensional stability is used, various problems may occur unexpectedly, and problems such as high costs may arise.
Therefore, it is conceivable to form a cured layer on both the front and back sides of the base film as in Patent Document 3 described above, but it is difficult to sufficiently increase the thermal dimensionality at a high temperature simply by forming the cured layer. I understand that.

On the other hand, among the conventionally disclosed conductive films, as in Patent Document 4, a resin layer containing inorganic particles or resin particles is formed on at least one surface of a transparent substrate film, and directly or on the resin layer. A transparent conductive film in which a transparent conductive layer is provided via another layer is disclosed.
Thus, by forming the resin layer containing inorganic particles or resin particles on at least one surface of the base film, not only can heat resistance be provided, but also blocking when the film is rolled up is prevented. be able to. On the other hand, by forming a resin layer containing inorganic particles or resin particles, there has been a problem that optical properties and device characteristics deteriorate due to light scattering caused by these inorganic particles or resin particles.

  Accordingly, an object of the present invention is to provide a new thermal dimensional stability at a high temperature (for example, 200 ° C. or higher) and anti-blocking properties, and yet does not adversely affect optical characteristics and device characteristics due to light scattering. It is to provide a transparent laminated film.

The present invention is a transparent laminated film having a crosslinked resin layer on both sides of the base film,
The total thickness of the cross-linked resin layer is 8% or more of the thickness of the base film, and at least one cross-linked resin layer contains particles satisfying the following condition (a) or (b): We propose a transparent laminated film with the characteristics.
(A) At least resin particles having an average particle size of 0.1 μm or more and less than 1.5 μm are contained in a proportion of more than 5% by mass and 50% by mass or less with respect to each crosslinked resin layer (100% by mass).
(B) containing at least resin particles having an average particle size of 0.1 μm or more and less than 1.5 μm in a proportion of 0.5% by mass or more and 5% by mass or less with respect to each cross-linked resin layer (100% by mass); Inorganic particles having an average particle diameter of 250 nm or less are contained in a proportion of 5% by mass or more and 50% by mass or less with respect to each crosslinked resin layer (100% by mass).

  The transparent laminated film proposed by the present invention has a cross-linked resin layer on both the front and back sides of the base film, and the total thickness of these cross-linked resin layers is 8% or more of the thickness of the base film. Even if the base film tries to shrink in the atmosphere, the cross-linked resin layer resists this, and the transparent laminated film as a whole can withstand the shrinkage stress, thus improving the thermal dimensional stability as the transparent laminated film. be able to. Specifically, the heat shrinkage ratio of the longitudinal transparent laminated film when heated at a temperature of 210 ° C. for 10 minutes is 80% or less of the heat shrinkage ratio of the longitudinal direction when the base film is heated under the same conditions. Thermal dimensional stability can be obtained. Therefore, since the transparent laminated film which this invention proposes can form a transparent conductive layer in high-temperature atmospheres, such as 150-220 degreeC, for example, by using this transparent laminated film, transparent conductivity with high crystallinity is used. A conductive film provided with a transparent conductive film having a low surface resistance can be formed.

  Furthermore, when at least one of the crosslinked resin layers contains particles satisfying the condition (a) or (b), it is possible to prevent blocking when the film is wound into a roll, In addition, light scattering is not caused by inorganic particles or resin particles, and optical characteristics and device characteristics are not deteriorated.

Since the transparent laminated film proposed by the present invention can obtain the advantages as described above, for example, a liquid crystal display, an organic light emitting display (OLED), an electrophoretic display (electronic paper), a touch panel, a color filter, a backlight, and the like. In addition to a display material substrate, a solar cell substrate, a photoelectric element substrate and the like can be suitably used.
Moreover, the transparent laminated film proposed by the present invention is used for applications that require dimensional stability at high temperatures, films for electronic components, gas barrier processing, semiconductor devices such as organic EL, liquid crystal display elements, It can be suitably used for solar cell applications.

  Next, an example of an embodiment of the present invention will be described. However, the present invention is not limited to the following embodiment.

[This laminated film]
A transparent laminated film according to an example of an embodiment of the present invention (hereinafter referred to as “the present laminated film”) is a transparent laminated film having a crosslinked resin layer on both sides of the base film.

<Base film>
As a base film used for this laminated film, any transparent resin film can be adopted arbitrarily. For example, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyphenylene sulfide resins, polyether sulfone resins, polyetherimide resins, transparent polyimide resins, polycarbonate resins, cyclic olefin homopolymers, cyclic olefin copolymers, etc. The film which consists of etc. can be mentioned. A film containing a resin composed of a combination of two or more of these can also be used.

  In addition, as said transparent polyimide resin, the cyclic | annular form contained in the structure of a polyimide resin other than what introduce | transduced the hexafluoro isopropylidene bond into the principal chain of the polyimide resin, the fluorinated polyimide which substituted the hydrogen in a polyimide with the fluorine Examples thereof include alicyclic polyimides hydrogenated with unsaturated organic compounds. For example, those described in JP-A-61-141738, JP-A-2000-292635 and the like can also be used.

Among the above, a film having poor thermal dimensional stability, for example, a base film that is thermally contracted in an atmosphere at a temperature of 150 to 220 ° C. can further enjoy the effects of the present invention. From such a viewpoint, the base film used for the laminated film has a glass transition temperature (Tg) of 130 ° C. or lower, preferably 50 ° C. to 130 ° C. or lower, more preferably 70 to 130 ° C. or lower as a main component. A resin film is preferred.
Among them, a film mainly composed of a polyethylene terephthalate resin and biaxially stretched is particularly preferable from the viewpoint of being generally used as a base film for a transparent conductive film.

<Crosslinked resin layer>
In the present laminated film, at least one of the crosslinked resin layers contains particles that satisfy the conditions (a) or (b) described later.
Here, the “crosslinked resin layer” means a layer formed by crosslinking a curable resin composition to form a crosslinked structure.
Under the present circumstances, the said curable resin composition may consist of a photopolymerizable compound, and contains a photoinitiator, a solvent, and other components as needed in addition to this photopolymerizable compound. It may be.
Next, each of these components will be described.

(Photopolymerizable compound)
Examples of the photopolymerizable compound include compounds having a polymerizable unsaturated bond, specifically, monomers or oligomers having an ethylenically unsaturated bond, and more specifically, urethane (meth) acrylate and epoxy. In addition to (meth) acrylate monomers or oligomers such as (meth) acrylate, polyester (meth) acrylate, polyether (meth) acrylate, and polycarbonate (meth) acrylate, monofunctional or polyfunctional (meth) acrylate monomers or oligomers Can be mentioned. These can be used alone or in combination of two or more.
The term “monomer” means that the structural unit having a polymerizable functional group is not repeated, and the term “oligomer” means that the number of repeating structural units having a polymerizable functional group is 2 or more and the molecular weight is It represents less than 5000.

  Examples of the monofunctional or polyfunctional (meth) acrylate monomer include ethyl (meth) acrylate, n-butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and hydroxyethyl (meth). Monofunctional monomers such as acrylate, hydroxypropyl (meth) acrylate, phenyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentenyl (meth) acrylate, diethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol diacrylate, 1,10-decanediol diacrylate, tricyclodecane dimethanol diacrylate, polyester Lenglycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, 2,2'-bis (4- (meth) acryloyloxypolyethyleneoxyphenyl) propane, 2,2'-bis (4- (meth) acryloyloxy Bifunctional monomers such as polypropyleneoxyphenyl) propane, trimethylolpropane tri (meth) acrylate, ethylene oxide modified trimethylolpropane tri (meth) acrylate, caprolactone modified trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate Trifunctional acrylate monomers such as tris (2-hydroxyethyl) isocyanurate tri (meth) acrylate, propoxylated glyceryl tri (meth) acrylate, and ditrime Tetrafunctional acrylate monomers such as roll propane tetra (meth) acrylate and pentaerythritol tetra (meth) acrylate, pentafunctional monomers such as dipentaerythritol hydroxypenta (meth) acrylate, and 6 such as dipentaerythritol hexa (meth) acrylate Examples include functional acrylate monomers. In addition, these can be used 1 type or in combination of 2 or more types.

Among these, it is preferable to use a polyfunctional acrylate monomer having two or more acryloyl groups or methacryloyl groups in one molecule because it can be crosslinked relatively easily when irradiated with ultraviolet rays.
In addition, by having two or more of these functional groups, the symmetry of the molecule increases, and as a result, the dipole moment of the molecule decreases, and it becomes possible to suppress aggregation of fine particles, particularly inorganic particles. .

  Among these, an alicyclic polyfunctional acrylate monomer having an alicyclic structure or a polyfunctional urethane having three or more acryloyl groups or methacryloyl groups in one molecule is particularly excellent in heat shrink stability. Acrylate monomers are particularly preferred. These acrylate monomers may be modified with caprolactone or the like, or two or more of the above may be used in combination.

The molecular weight of the photopolymerizable compound is preferably in the range of 215 to 4000, more preferably 250 or more and 3000 or less, and more preferably 300 or more and 2000 or less. By using a photopolymerizable compound having such a molecular weight range, the molecular weight is too low, and the possibility that the monomer is adsorbed to the inorganic particles in the drying process or the like can be eliminated, while the molecular weight is too high. Further, the viscosity of the curable resin composition becomes excessively large, the dispersion of the fine particles is suppressed, and problems such as the fine particles being aggregated can be eliminated. As a result, the crosslinked resin layer can more effectively suppress shrinkage of the base film at high temperatures.
In addition, in this invention, when the molecular weight of a photopolymerizable compound exceeds 1500, it shall represent the molecular weight as a weight average molecular weight (Mw).

(Photopolymerization initiator)
Examples of the photopolymerization initiator include benzoin, acetophenone, thioxanthone, phosphine oxide, and peroxide photopolymerization initiators. Specific examples of the photopolymerization initiator include, for example, benzophenone, 4,4-bis (diethylamino) benzophenone, 2,4,6-trimethylbenzophene, methylorthobenzoylbenzoate, 4-phenylbenzophenone, and t-butyl. Anthraquinone, 2-ethylanthraquinone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -Benzyl] phenyl} -2-methyl-propan-1-one, benzyl dimethyl ketal, 1-hydroxycyclohexyl-phenyl ketone, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2-methyl Ru- [4- (methylthio) phenyl] -2-morpholino-1-propanone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1, diethylthioxanthone, isopropylthioxanthone, 2,4 , 6-Trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, methylbenzoylformate Etc. can be illustrated. These can be used alone or in combination of two or more.

(Filler)
At least one of the crosslinked resin layers preferably contains particles that satisfy the following conditions (a) or (b). Since it is at least one cross-linked resin layer, the other cross-linked resin layer may or may not contain particles satisfying the condition (a) or (b). Details will be described later.

(A) At least resin particles having an average particle diameter of 0.1 μm or more and less than 1.5 μm are contained in a proportion of more than 5% by mass and 50% by mass or less with respect to each crosslinked resin layer (100% by mass).
(B) containing at least resin particles having an average particle size of 0.1 μm or more and less than 1.5 μm in a proportion of 0.5% by mass or more and 5% by mass or less with respect to each crosslinked resin layer (100% by mass); Inorganic particles having an average particle diameter of 250 nm or less are contained in a proportion of 5% by mass or more and 50% by mass or less with respect to each crosslinked resin layer (100% by mass).

(Condition (a))
When the crosslinked resin layer contains particles, high-temperature dimensional stability can be further improved. Moreover, since the resin particles have a refractive index difference close to that of the resin constituting the crosslinked resin layer, even if the particles are relatively large, transparency can be ensured and light scattering does not occur. Are more effective at larger particles. Therefore, when only the resin particles are contained as a filler in the crosslinked resin layer, the resin particles having an average particle diameter of 0.1 μm or more and less than 1.5 μm are added from 5% by mass with respect to each crosslinked resin layer (100% by mass). It is preferable to make it contain in the ratio of many and 50 mass% or less.

From this point of view, in the condition (a), the average particle diameter of the resin particles is preferably 0.1 μm or more and less than 1.5 μm, more preferably 0.3 μm or more or 1.2 μm or less, and more preferably 0.5 μm. It is particularly preferable that the thickness is 1.2 μm or less.
The content of the resin particles is preferably greater than 5% by mass and less than 50% by mass with respect to each cross-linked resin layer (100% by mass). Hereinafter, among them, the content is more preferably 10% by mass or more and 20% by mass or less.

(Condition (b))
Since the inorganic particles have a difference in refractive index from the resin constituting the crosslinked resin layer, if the particle size is not small, transparency cannot be ensured or light scattering occurs. On the other hand, from the viewpoint of preventing blocking, it is effective to contain resin particles having a relatively large particle size and no difference in refractive index from the resin constituting the crosslinked resin layer.
Therefore, when inorganic particles are contained in the crosslinked resin layer as a filler, inorganic particles having an average particle diameter of 250 nm or less are contained in a proportion of 5% by mass or more and 50% by mass or less with respect to each crosslinked resin layer (100% by mass). In addition, the resin particles having an average particle size of 0.1 μm or more and less than 1.5 μm are preferably contained in a proportion of 0.5% by mass or more and 5% by mass or less with respect to each crosslinked resin layer (100% by mass). .

From this viewpoint, in the condition (b), the average particle diameter of the inorganic particles is 250 nm or less, preferably 1 nm or more or 200 nm or less, more preferably 5 nm or more or 100 nm or less. The content with respect to (100% by mass) is preferably 5 to 50% by mass, more preferably 5% by mass or more and 40% by mass or less, and particularly preferably 10% by mass or more or 35% by mass or less.
The average particle size of the resin particles is preferably 0.1 μm or more and less than 1.5 μm, particularly 0.3 μm or more or 1.2 μm or less, and particularly preferably 0.5 μm or more or 1.2 μm or less. Preferably, the content of the resin particles with respect to each cross-linked resin layer (100% by mass) is preferably 0.5 to 5% by mass, more preferably 0.5% by mass or more or 4.8% by mass or less. It is particularly preferably 0.7% by mass or more or 4.5% by mass or less.

  Examples of the resin particles include resin particles such as acrylic resin, polyurethane resin, polystyrene resin, polyester resin, polyolefin resin, polyamide resin, polycarbonate resin, silicone resin, and fluorine resin. Among these, when the component serving as the base of the crosslinked resin layer is an acrylate monomer, acrylic particles are particularly preferable from the viewpoint that the refractive index is close to this and the transparency is high.

(Inorganic particles)
Examples of the inorganic particles include inorganic particles made of silicon oxide (silica), aluminum oxide, titanium oxide, soda glass, diamond, and the like.
Among these, silicon oxide (silica) fine particles are preferable from the viewpoint of hardness, coating suitability, price, and the like.

  In addition, when using a photopolymerizable compound as a base such as silicon oxide (silica), for example, inorganic particles having a large difference in refractive index from the acrylate monomer, use inorganic particles having an average particle diameter in the range of 5 nm to 250 nm. Is particularly preferred. By using fine particles in such a range, the transparency of the film can be secured without causing a scattering phenomenon with respect to incident light due to the Mie scattering phenomenon.

Specific examples of the silicon oxide fine particles include dried powdered silicon oxide fine particles, colloidal silica (silica sol) dispersed in an organic solvent, and the like. For example, from the viewpoint of dispersibility, it is preferable to use colloidal silica (silica sol) dispersed in an organic solvent.
As the silicon oxide fine particles, surface-modified fine particles can be used. By using the surface-shrinked silicon oxide fine particles, dispersibility in the curable resin composition is improved, and a uniform cured film can be formed. For example, for the purpose of improving the dispersibility, it is possible to use a silane coupling agent, a titanate coupling agent, etc. as long as the properties such as transparency, solvent resistance, liquid crystal resistance, and heat resistance are not significantly impaired. The surface-treated silicon oxide fine particles or silicon oxide fine particles that have been subjected to easy dispersion treatment on the surface may be used.

  In order to reduce the amount of refracted light incident on the crosslinked resin layer, the refractive index of the inorganic particles is preferably less than 1.6. Among these, from the viewpoint of improving transparency, a resin that is a reaction product after polymerization / curing of the curable resin composition, particularly fine particles having a refractive index difference between the resin constituting the main component and the inorganic particles of less than 0.2 are used. Is preferred.

  As a preferred example, at least one cross-linked resin layer contains acrylic particles having an average particle diameter of 0.1 μm or more and less than 1.5 μm in an amount of 0.5% by mass to 5% by mass with respect to each cross-linked resin layer (100% by mass) As an example, a case where silicon oxide fine particles having an average particle diameter of 250 nm or less are contained in a proportion of 5% by mass or more and 50% by mass or less with respect to each cross-linked resin layer (100% by mass). Can do.

  The above-mentioned “average particle diameter” of the resin particles and inorganic particles means the number average particle diameter. When the shape of the fine particles is spherical, “the sum of the equivalent circle diameters of the measurement particles / the measurement particle In the case where the shape of the fine particles is not spherical, it can be calculated by “the sum of the short diameter and the long diameter / number of measured particles”.

(solvent)
The curable resin composition can be used by adding a solvent if necessary. That is, it can be used as a solution (also referred to as a paint) containing the curable resin composition, and this solution can be applied to a base film and cured to form a crosslinked resin layer as a cured coating layer.
Depending on the various coating methods described below, the type and amount of the solvent can be appropriately selected.

  Examples of the solvent include ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, esters such as ethyl acetate and butyl acetate, aromatics such as toluene and xylene, and cyclohexanone and isopropanol.

  The amount of these solvents used is not particularly limited. Usually, it is 0-300 mass parts with respect to 100 mass parts of solid content whole quantity of curable resin composition.

(Other ingredients)
In addition to the above, for example, in order to adjust physical properties such as curability, water absorption and hardness of the crosslinked resin layer, polymer components such as poly (meth) acrylic acid ester, epoxy resin, polyurethane resin, polyester resin, It can add arbitrarily with respect to the said curable resin composition. In addition, these can be used 1 type or in combination of 2 or more types as appropriate.
In addition, photocurable oligomers / monomers, photoinitiators, sensitizers, crosslinkers, UV absorbers, polymerization inhibitors, fillers, thermoplastic resins, etc. can be made into physical properties such as curability, transparency and water absorption. It can be contained as long as it does not hinder.

(Mixing ratio)
As content of the said photopolymerizable compound contained in the said curable resin composition, it is 20-90 mass% or less with respect to the whole curable resin composition (in the case of using a solvent, solid content conversion, the following The same), preferably 20 to 60% by mass or less, more preferably 20 to 40% by mass or less. When the content of the photopolymerizable compound is small, it becomes difficult to disperse the fine particles, so that the fine particles are aggregated and the transparency is remarkably deteriorated. In addition, since the content of the photopolymerizable compound is not too high, the contribution of the fine particles to the thermal dimensional stability of the entire film is halved, eliminating the possibility that the excellent thermal dimensional stability of the fine particles cannot be exhibited. be able to.

  What is necessary is just to contain a photoinitiator as needed. When the photopolymerization initiator is contained, the content of the photopolymerization initiator contained in the curable resin composition is 0.1% by mass to 10% by mass or less based on the entire curable resin composition. It is preferable to be 0.5 mass% to 5 mass% or less. By setting it as such a range, it becomes possible to advance hardening reaction reliably and efficiently.

As a mixing ratio of the photopolymerizable compound and fine particles contained in the curable resin composition, the photopolymerizable compound (hereinafter, also simply referred to as (A)) is 20 to 100% by mass or less and the fine particles (hereinafter referred to as “A”). , Simply referred to as (C)) is preferably 0 to 80 mass% or less, (A) is 20 to 90 mass% or less, and (C) is 10 to 80 mass% or less. More preferred.
The mixing ratio of (A), photoinitiator (hereinafter also simply referred to as (B)) and (C) contained in the curable resin composition is 20 to 79 mass or less. %, (B) is 0.1 to 10% by mass or less and (C) is preferably 10 to 79% by mass or less, and (A) is 20 to 59% by mass or less, a photopolymerization initiator ( More preferably, B) is 0.5 to 5% by mass or less and (C) is 40 to 79% by mass or less, (A) is 20 to 39% by mass or less, and (B) is 0.5 to 5% by mass. % Or less and (C) are most preferably 60 to 79% by mass or less. By making such a mixing ratio, it becomes possible to efficiently and stably supply a laminated film having transparency and productivity while maximizing the excellent thermal dimensional stability of the fine particles. .

In addition, as above-mentioned, the other crosslinked resin layer may contain the particle | grains which satisfy the conditions of said (a) or (b), and does not need to contain a particle | grain. By forming the other crosslinked resin layer from a curable resin composition that does not contain particles, surface protrusions and foreign matters on the other crosslinked resin layer can be minimized, so it is preferable not to contain particles.
However, in the case of using this laminated film as a substrate for device production, it is preferable to form it only from a curable resin composition without containing a resin in order to eliminate surface protrusions and foreign matters that affect the device. More specifically, it may be formed from a photocurable resin composition containing a photopolymerization initiator as required in addition to the above-mentioned photopolymerizable compound.

<Thickness configuration of the laminated film>
In this laminated film, the thermal shrinkage rate of the longitudinal transparent laminated film when heated at a temperature of 210 ° C. for 10 minutes is 80% or less of the longitudinal thermal shrinkage rate when the base film is heated under the same conditions. Therefore, it is preferable that a cross-linked resin layer is formed on both the front and back sides of the base film, and the total thickness of the cross-linked resin layers on both the front and back sides is 8% or more of the base film. % Or more, more preferably 15% or more or 50% or less, particularly preferably 20% or more or 45% or less, more preferably more than 30% and 45% or less. Most preferred.
When the cross-linked resin layer is thin, the rigidity of the entire laminated film is reduced, and it is difficult to suppress shrinkage of the base film at high temperatures. On the other hand, if the crosslinked resin layer is excessively thick, cracks and cracks are likely to occur, which is not preferable.

The thickness of the base film is preferably less than 100 μm, more preferably 5 μm or more and 70 μm or less, more preferably 10 μm or more, and more preferably 20 μm or more or 60 μm or less. Most preferred. By setting it as such a range, advantages, such as an improvement in light transmittance and high handling performance, can be obtained.
A resin film used as a substrate material for a touch panel, an organic EL display, or an organic EL lighting is required to have a thin film thickness in order to reduce weight, thickness, and cost. In general, when a resin film is obtained by extrusion molding, in order to reduce the thickness, the molten resin can be stretched and thinned, or a resin film heated to a glass transition temperature or higher can be stretched. That is, as the resin film is made thinner, the external stress applied to the molding increases, resulting in a resin film with a large residual stress. Therefore, when a resin film having a thickness of 100 μm or less is used for an application that undergoes a high-temperature process such as circuit formation, the problem is that this residual stress is relaxed at a high temperature and a dimensional change occurs.
Therefore, by providing a cross-linked resin layer such that the total thickness is 8% or more of the base film on both the front and back sides of the base film having a specific thickness, specifically less than 100 μm, particularly 70 μm or less, The crosslinked resin layer remarkably suppresses the shrinkage of the base film at a high temperature, and it becomes possible to obtain a transparent laminated film excellent in thermal dimensional stability.

<Laminated structure>
In the present laminated film, a cross-linked resin layer may be directly laminated on the front and back surfaces of the base film, and another layer may be interposed between the base film and the cross-linked resin layer. For example, a primer layer or the like for improving the adhesion of the crosslinked resin layer to the substrate film can be interposed between the substrate film and the crosslinked resin layer.

<Heat setting process>
This laminated film is provided with a predetermined cross-linked resin layer on both the front and back sides of the base film, so that the base film is transparent and has a heat dimension at a high temperature (for example, 200 ° C. or higher) without performing a heat setting treatment. A transparent laminated film excellent in stability can be obtained. However, it is also possible to use a film that has been heat-set to alleviate shrinkage.
Before applying the curable resin composition on the base film, the dimensional stability of the base film and the laminated film can be further improved by subjecting the base film to a heat setting process in advance.
Among these, a biaxially stretched polyester film that has been heat-set to alleviate shrinkage is a preferred example of a substrate film.

  In the heat setting treatment of the base film, the base film is preferably heat-treated at a temperature of Tg to Tg + 100 ° C. for 0.1 to 180 minutes when the glass transition temperature of the base film is Tg.

  The specific method of heat-setting process will not be specifically limited if it is a method which can maintain required temperature and time. For example, a method of storing in an oven or temperature-controlled room set to the required temperature, a method of blowing hot air, a method of heating with an infrared heater, a method of irradiating light with a lamp, a direct contact with a hot roll or hot plate A method of imparting a light, a method of irradiating with a microwave, or the like can be used. Moreover, even if it heat-processes after cut | disconnecting a film to the magnitude | size which is easy to handle, you may heat-process with a film roll. Furthermore, as long as necessary time and temperature can be obtained, a heating device can be incorporated in a part of a film production apparatus such as a coater or a slitter, and heating can be performed in the production process.

<Physical properties>
Next, various physical properties that the laminated film can have will be described.

(Heat shrinkage)
This transparent laminated film has a thermal contraction rate in the vertical direction when heated at 210 ° C. for 10 minutes, which is 80% or less, particularly 75% or less, in the vertical direction when the base film is heated under the same conditions. Is preferred.
By providing a cross-linked resin layer having a thickness of 8% or more of the thickness of the base film on both the front and back sides of the base film, the cross-linked resin layer counteracts the shrinkage stress of the base film in a high temperature region to reduce shrinkage. can do. Therefore, the thermal dimensional stability of the transparent laminated film against shrinkage at a high temperature can be improved as described above. Therefore, this transparent laminated film has the advantage that the dimensional deviation at the time of forming a circuit and an element is reduced, and higher barrier properties can be obtained when the inorganic barrier layer is laminated.

Especially, it is preferable that this laminated film has a thermal contraction rate in the longitudinal direction of 1.5% or less, particularly 1.45% or less when heated at a temperature of 210 ° C. for 10 minutes.
Especially for biaxially stretched films, it is possible to reduce the shrinkage rate by the transverse relaxation treatment during the film forming process, but the longitudinal relaxation treatment often requires a separate process. In particular, the contraction rate in the vertical direction becomes relatively large. Therefore, it is preferable to reduce the shrinkage rate in the longitudinal direction in the laminated film.

  Since this laminated film has high thermal dimensional stability at a high temperature in this way, it is transparent in a high temperature atmosphere (specifically, 150 to 220 ° C.) when forming a transparent conductive layer on the transparent laminated film. A conductive layer can be formed. As a result, crystallization of the transparent conductive layer can be sufficiently increased, and the surface resistance value of the transparent conductive layer can be sufficiently reduced.

<Manufacturing method>
This transparent laminated film can be produced by applying a curable resin composition on both the front and back sides of the base film and curing it to form a crosslinked resin layer.

  Examples of the method for coating the curable resin composition include bar coater coating, Mayer bar coating, air knife coating, gravure coating, reverse gravure coating, offset printing, flexographic printing, screen printing, and dip coating. For example, a method of applying the curable resin composition to the base film can be mentioned. It is also effective to transfer a molded crosslinked resin layer to a base film after molding the crosslinked resin layer on glass or a polyester film.

  As described above, the method of curing (crosslinking) the curable resin composition after coating the curable resin composition on the base film may be a method such as thermosetting, ultraviolet curing, or electron beam curing. They can be used in combination. Among them, it is preferable to use an ultraviolet curing method because curing can be achieved relatively easily in a short time.

Curing with ultraviolet rays can be carried out by using an ultraviolet irradiation device having a xenon lamp, a high-pressure mercury lamp, or a metal halide lamp as a light source, and adjusting the amount of light, the arrangement of the light source, etc. as necessary.
When using the above high-pressure mercury lamp, it is preferable to cure at a conveyance speed of 5 to 60 m / min with respect to one lamp having a light quantity of 80 to 160 W / cm.
On the other hand, when curing with an electron beam, it is preferable to use an electron beam accelerator having an energy of 100 to 500 eV.

<Application>
This laminated film is used as, for example, a transparent laminated film that can be used as a substrate material for solar cells, organic solar cells, flexible displays, organic EL lighting, touch panels, etc., and a transparent substrate provided with this as a base material. Can do. However, it is not limited to these uses.
More specifically, a conductive film (referred to as “the present conductive film”) can be produced by forming a transparent conductive layer on the laminated film directly or through an undercoat layer made of a resin material. .

[This conductive film]
Next, the present conductive film as an example of the use of the present laminated film, that is, a structure in which a transparent conductive layer is formed directly on the laminated film or through an undercoat layer made of a resin material is provided. The conductive film will be described.

<Transparent conductive layer>
In the present conductive film, the material of the transparent conductive layer is not particularly limited. Any material that can form a transparent conductive film may be used. For example, indium oxide containing tin oxide (ITO), tin oxide containing antimony (ATO), zinc oxide, zinc-aluminum composite oxide, indium-zinc composite oxide, as well as indium oxide, zinc oxide and gallium oxide A thin film such as a complex oxide containing IGZO. These compounds can achieve both transparency and conductivity by selecting appropriate production conditions.

  The thickness of the transparent conductive layer is preferably less than 100 nm, more preferably 15 nm or more or 50 nm or less, and most preferably 20 nm or more or less than 40 μm. In the past, attempts have been made to increase the thickness of the conductive layer in order to reduce the surface resistance value of the transparent conductive film (for example, less than 150Ω / □). Since it has dimensional stability, it is possible to form a conductive layer at a high temperature, and a sufficiently low surface low resistance value can be obtained without increasing the thickness of the conductive layer.

  Known methods for forming a transparent conductive layer include vacuum deposition, sputtering, CVD, ion plating, and spraying. Select an appropriate method according to the type of material and the required film thickness. Can be used. For example, in the case of a sputtering method, normal sputtering using a compound target, reactive sputtering using a metal target, or the like is used. At this time, a reactive gas such as oxygen, nitrogen or water vapor can be introduced, or means such as addition of ozone or ion assist can be used in combination.

  As a formation condition of the said transparent conductive layer, it is preferable that it is the range of temperature 150 to 220 degreeC. For example, when forming a transparent conductive layer on a film by sputtering method, normal sputtering temperature is about room temperature-about 100 degreeC. On the other hand, since this laminated film is excellent in thermal dimensional stability as described above, it can be sputtered even at a relatively high temperature (150 ° C. to 220 ° C.) as described above. Crystallization of the conductive layer can be sufficiently promoted, and a transparent conductive film having a small surface resistance value can be obtained.

<Undercoat layer>
When forming a transparent conductive layer on this laminated film, it is preferable to form a transparent conductive layer through an undercoat layer. By interposing the undercoat layer, the adhesion and crystallinity of the transparent conductive layer can be improved. Among these, when particles (fillers) are contained in the crosslinked resin layer, it is preferable to interpose an undercoat layer when forming the transparent conductive layer on the laminated film. By interposing the undercoat layer in this way, the surface resistance value of the conductive film can be reduced because the surface smoothness can be increased and the continuity of the transparent conductive layer can be increased.

The material for the undercoat layer is not particularly limited as long as it is a resin material. For example, poly (meth) acrylic acid ester, epoxy resin, polyurethane resin, polyester resin, and the like can be suitably used. In addition, an undercoat layer can be formed by using a composition containing a photo- or heat-polymerizable compound and polymerizing the composition.
In addition, since it may inhibit the crystal growth of a transparent conductive layer if the flatness of an undercoat layer is bad, it is preferable that an undercoat layer does not have a fine particle substantially.

<Physical properties>
Next, various physical properties that the conductive film can have will be described.

(Surface resistance value)
The surface resistance value of the conductive film is preferably 150Ω / □ or less, and more preferably 100Ω / □ or less. Advantages such as reducing the power transmission loss of the display device and reducing the response speed variation when the touch panel sensor is enlarged because the conductive film has a surface resistance value in this range. Have
By forming the inorganic oxide film in a temperature atmosphere of 150 to 220 ° C., the crystallinity of the inorganic oxide film can be increased, and thus the surface resistance value can be increased.

<Application>
As described above, the conductive film has the advantages that the dimensional change (thermal dimensional stability) due to heat treatment is small and the surface resistance value is small while maintaining transparency. In addition to a display material substrate such as a display (OLED), an electrophoretic display (electronic paper), and a touch panel, a substrate of a solar cell, it can be suitably used for a photoelectric element substrate and the like.
In addition, since the conductive film has the advantages as described above, it is suitably used for semiconductor devices such as organic EL, liquid crystal display elements, and solar cells by performing gas barrier processing as described below. be able to.

<This barrier film>
This conductive film is used as a transparent conductive film having a barrier film property (referred to as “the present barrier film”) by subjecting one or both of the crosslinked resin layers provided on the base film to gas barrier processing. You can also.
Conventionally, when a polyester film is used as a gas barrier processing film, the gas barrier layer is cracked or wrinkled, and there is a problem that the function including gas barrier properties cannot be fully exhibited. On the other hand, this barrier film is excellent in that there is no such problem.

  This barrier film can be suitably used for organic semiconductor devices such as organic EL, liquid crystal display elements, and other applications that require gas barrier properties and conductivity, such as solar cells.

The gas barrier processing is a processing method in which a gas barrier layer made of a material having high gas barrier properties such as an inorganic substance such as a metal oxide or an organic substance is formed on at least one surface of the laminated film.
In this case, examples of materials having high gas barrier properties include silicon, aluminum, magnesium, zinc, tin, nickel, titanium, and oxides, carbides, nitrides, oxycarbides, oxynitrides, oxycarbonitrides, diamonds of these. Like carbon or a mixture thereof may be used. In addition, silicon oxide, silicon oxycarbide, silicon oxynitride, silicon oxycarbonitride, aluminum oxide, aluminum oxycarbide, aluminum oxynitride, etc. are used because there is no fear of leakage of current when used for solar cells, etc. Inorganic oxides, nitrides such as silicon nitride and aluminum nitride, diamond-like carbon, and mixtures thereof are preferred. In particular, silicon oxide, silicon oxycarbide, silicon oxynitride, silicon oxycarbonitride, silicon nitride, aluminum oxide, aluminum oxycarbide, aluminum oxynitride, aluminum nitride, and mixtures thereof can stably maintain high gas barrier properties. Is preferable.

As a method for forming a gas barrier layer on the conductive film using the above material, any known method such as a vapor deposition method or a coating method can be employed. The vapor deposition method is preferable in that a uniform thin film having a high gas barrier property can be obtained.
This vapor deposition method includes methods such as physical vapor deposition (PVD) or chemical vapor deposition (CVD).
Examples of the physical vapor deposition method include vacuum deposition, ion plating, and sputtering.
Examples of the chemical vapor deposition method include plasma CVD using plasma, and catalytic chemical vapor deposition (Cat-CVD) in which a material gas is contact pyrolyzed using a heated catalyst body.

The thickness of the gas barrier layer is preferably 10 nm to 1000 nm from the viewpoint of stable gas barrier properties and transparency, more preferably 40 nm or more and 800 nm or less, particularly 50 nm or more and 600 nm or less. Is more preferable.
The gas barrier layer may be a single layer or a multilayer. When the gas barrier layer is a multilayer, each layer may be made of the same material or different materials.

The water vapor transmission rate at 90 ° C. of the barrier film is preferably less than 0.1 [g / (m ² · day)], more preferably 0.06 [g / (m ² · day)] or less, Preferably, it is 0.03 [g / (m ² · day)] or less.
The method for measuring the water vapor transmission rate is in accordance with various conditions of JISZ0222 “moisture-proof packaging container moisture permeability test method” and JIS Z0208 “moisture-proof packaging material moisture permeability test method (cup method)”, and specifically described in the examples. It is measured by the method.

<Explanation of terms>
In the present specification, when expressed as “X to Y” (X and Y are arbitrary numbers), unless otherwise specified, “X is preferably greater than X” or “preferably Y”. It also includes the meaning of “smaller”.
In addition, when expressed as “X or more” (X is an arbitrary number) or “Y or less” (Y is an arbitrary number), it is “preferably greater than X” or “preferably less than Y”. Includes intentions.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited in any way by these examples.

(Measurement method of thermal shrinkage)
From the transparent laminated film obtained in Examples / Comparative Examples and the base film used therefor, the film is cut into strips having a length of 140 mm × width of 10 mm in the vertical direction and the horizontal direction, and at intervals of 100 mm in the middle. A test line was prepared by writing a marked line. The test piece was suspended in a thermostatic chamber set at 210 ° C. for 10 minutes with no load, taken out, allowed to cool at room temperature for 15 minutes or more, and the length between the marked lines before and after being placed in the thermostatic chamber. From the above, the heat shrinkage percentage was obtained as a% value.
In addition, the measurement was performed 5 times, the average value was calculated, and the value rounded to the third decimal place was described.
The thermal shrinkage was measured in the machine direction (MD), which is the longitudinal direction of the film. Table 1 shows the thermal shrinkage obtained.

(Measurement method of blocking resistance)
Two transparent laminated films obtained in Examples and Comparative Examples were prepared, and the first surface cross-linked resin layer and the second surface cross-linked resin layer were in close contact with each other at 100 g / 4.9 cm ² . Pressurized for 30 seconds. Thereafter, the blocking state between the first surface cross-linked resin layer and the second surface cross-linked resin layer was observed and evaluated in the following manner.
The case where the first surface cross-linked resin layer and the second surface cross-linked resin layer are not in close contact is evaluated as “good”, and the first surface cross-linked resin layer and the second surface cross-linked resin layer are in close contact, When pasted, it was evaluated as “× (poor)”.

(Measurement method of total light transmittance and haze)
The total light transmittance and haze of the films obtained in the examples and comparative examples were measured by the method according to JIS K7361 and K7136 using the following apparatus.
Reflectance / transmittance meter: Murakami Color Research Laboratory "HR-100"

[Example 1]
(Preparation of UV-curable monomer composition A)
25% by mass of photocurable hexafunctional acrylate monomer (dipentaerythritol hexaacrylate, molecular weight 578, manufactured by Shin-Nakamura Chemical Co., Ltd., trade name “A-DPH”), photocurable hexafunctional urethane acrylate (molecular weight about 800, Shin-Nakamura Chemical Co., Ltd., trade name “U-6LPA” 50 mass%, photocurable bifunctional acrylate monomer (tricyclodecane dimethanol diacrylate, molecular weight 304, Shin-Nakamura Chemical Co., Ltd., trade name “ A-DCP "25% by mass was uniformly mixed to obtain an ultraviolet curable monomer composition A.

(Preparation of curable resin composition 1)
12.7 parts by mass of acrylic resin particles (manufactured by Soken Chemical Co., Ltd., trade name “MP-300”, average particle size 0.1 μm), 84.7% by mass of UV curable monomer composition A, and photopolymerization initiator 2.6% by mass (trade name “IRGACURE184”, manufactured by BASF) is uniformly diluted with a solvent (ethyl methyl ketone and propylene glycol monomethyl ether), and a curable resin composition 1 for forming a first cross-linked resin layer 1 Got.

(Preparation of curable resin composition 2)
UV-curable monomer composition A 97.1% by mass and photopolymerization initiator (BASF, trade name “IRGACURE 184”) 2.9% by mass are uniformly diluted with a solvent (ethyl methyl ketone and propylene glycol monomethyl ether). Thus, a curable resin composition 2 for forming the second surface cross-linked resin layer was obtained.

(Preparation of transparent laminated film 1)
Biaxially stretched polyethylene terephthalate film having a thickness of 50 μm (manufactured by Mitsubishi Plastics Co., Ltd., heat shrinkage rate based on the above-described measurement method: machine direction (MD) = 1.91%, transverse direction (TD) = 0.25% The curable resin composition 1 prepared above was applied on one side using a wire bar coater so that the thickness after curing was 3 μm, and then the solvent was dried and removed. Furthermore, it is put in a belt conveyor apparatus in a state where the end of the film is fixed, and a high-pressure mercury lamp (160 W / cm) is irradiated on the coating surface, and a photo-curing property is applied to one side of a biaxially stretched polyethylene terephthalate film (base film). A film having a first surface cross-linked resin layer was obtained.
By applying and curing the curable resin composition 2 on the surface of the film on which the crosslinked resin layer is not formed in the same manner as described above, a photocurable second surface crosslinked resin layer is formed, A transparent laminated film 1 (sample) having a crosslinked resin layer formed on both surfaces of the film was obtained.
Table 1 shows the results of evaluating the transparent laminated film 1 (sample) in the manner described above.

[Examples 2 to 5 and Comparative Examples 1 to 5]
Except for preparing the curable resin composition for forming the first surface cross-linked resin layer and the curable resin composition for forming the second surface cross-linked resin layer with the composition shown in Table 1, the same as in Example 1, A transparent laminated film (sample) was obtained.
Table 1 shows the results of evaluation performed on each of the transparent laminated films (samples) in the same manner as in Example 1.

[Comparative Example 6]
Table 1 shows the results of evaluating the biaxially stretched polyethylene terephthalate film (trade name “Diafoil”, manufactured by Mitsubishi Plastics, Inc.) having a thickness of 50 μm in the same manner as in Example 1.

[Example 6]
(Preparation of UV curable monomer composition B)
50% by mass of a composition containing a photocurable hexafunctional acrylate monomer (made by Shin-Nakamura Chemical Co., Ltd., trade name “U-6LPA”, a mixture of a hexafunctional urethane acrylate monomer and a tetrafunctional acrylate monomer), and photocurable 3 A functional acrylate monomer (pentaerythritol triacrylate, molecular weight 298, manufactured by Shin-Nakamura Chemical Co., Ltd., trade name “A-TMM-3LM-N”) 50% by mass is uniformly mixed to obtain an ultraviolet curable monomer composition B. It was.

(Preparation of curable resin composition 3)
Acrylic fine particles (manufactured by Soken Chemical Co., Ltd., trade name “MX80H3wT”, average particle size 0.8 μm) 0.7 mass%, silica fine particle MEK dispersion (MEK-ST-L, solid content 30%) 22.6 mass % (Solid content conversion), UV-curable monomer composition B 75.2% by mass, photopolymerization initiator (manufactured by BASF, trade name “IRGACURE127”) 1.5% by mass, solvent (ethyl methyl ketone and propylene) Diluted uniformly with glycol monomethyl ether) to obtain a curable resin composition 3 for forming a first cross-linked resin layer.

(Preparation of curable resin composition 4)
The UV curable monomer composition B 98% by mass and the photopolymerization initiator (BASF, trade name “IRGACURE127”) 2% by mass are uniformly diluted with a solvent (ethyl methyl ketone and propylene glycol monomethyl ether) A curable resin composition 4 for forming a surface cross-linked resin layer was obtained.

(Preparation of transparent laminated film 2)
Biaxially stretched polyethylene terephthalate film having a thickness of 23 μm (manufactured by Mitsubishi Plastics Co., Ltd., heat shrinkage rate in accordance with the measurement method of Example 1: longitudinal direction (MD) = 2.96%, lateral direction (TD) = 1.03) %) Was applied to the surface of the curable resin composition 3 prepared above using a gravure coater so that the thickness after curing was 1 μm, and then the solvent was dried and removed. A film having a photocurable first surface cross-linked resin layer on one side of a biaxially stretched polyethylene terephthalate film (base material film) was obtained by irradiation with a lamp (160 W / cm).
By applying and curing the curable resin composition 4 on the surface of the film on which the crosslinked resin layer is not formed in the same manner as described above, a photocurable second surface crosslinked resin layer is formed, A transparent laminated film 2 (sample) in which a crosslinked resin layer was formed on both surfaces of the film was obtained.
Table 1 shows the results of evaluating the transparent laminated film 2 (sample) in the same manner as in Example 1.

The contents of the product numbers shown in Table 1 below are as follows.
MP-300: average particle size 0.1 μm acrylic particles (manufactured by Soken Chemical Co., Ltd.)
MX-80H3wT: average particle diameter 0.8 μm acrylic particles (manufactured by Soken Chemical Co., Ltd.)
MX-150: average particle size 1.5 μm acrylic particles (manufactured by Soken Chemical Co., Ltd.)
YA010C-SM1: Silica particles having an average particle size of 10 nm (manufactured by Admatechs)
MEK-ST-L: MEK dispersion with an average particle size of 50 nm silica particles (manufactured by Nissan Chemical Co., Ltd., solid content concentration 30%)
SC2050-MB: average particle size 500 nm silica particle MEK dispersion (manufactured by Admatechs Co., Ltd., solid content concentration 70%)
Photopolymerization initiator: 1-hydroxy-cyclohexyl-phenyl-ketone (manufactured by BASF, trade name “IRGACURE184”)

(Discussion)
From the results of Examples 1 to 6 and Comparative Examples 1 to 6, the following a) to e) became clear.
a) To make the heat shrinkage rate of the transparent laminated film in the vertical direction when heated at 210 ° C. for 10 minutes to 80% or less of the heat shrinkage rate in the vertical direction when the base film is heated under the same conditions It was found that the total thickness of the front and back sides of the cross-linked resin layer made of the curable resin composition must be 8% or more of the thickness of the base film, against the heat shrinkage of the base film. .
b) In order to achieve both blocking resistance under the above thickness conditions, the resin particles having an average particle diameter of 0.1 μm or more are included in at least one cross-linked resin layer (100 mass%) in an amount of more than 5 mass%, Alternatively, resin particles having an average particle diameter of 0.1 μm or more are included in at least a single-sided crosslinked resin layer (100 mass%) in a proportion of 0.5 mass% or more and 5 mass% or less, and the average particle diameter is 250 nm or less. It turned out that it is necessary to contain 5 mass% or more of inorganic particles.
c) In order to secure further transparency, if the particle size is large, the particles are excessively exposed on the surface of the crosslinked resin layer, leading to an increase in haze. Therefore, the average particle size of the resin particles contained in the crosslinked resin layer It has been found that the diameter needs to be less than 1.5 μm.
d) In addition, since the difference in refractive index from the ultraviolet curable monomer is large by using inorganic particles having an average particle size of 250 nm or less, light scattering occurs when the particle size is large, and there is no possibility of increasing haze. I also understood that.
e) Moreover, since thermal dimensional stability can be improved more by including a polyfunctional acrylate monomer, it turned out that it is more preferable that a crosslinked resin layer contains a polyfunctional acrylate monomer as a main material.

Claims (13)

In the transparent laminated film having a cross-linked resin layer on both sides of the base film,
The total thickness of the cross-linked resin layer is 8% or more of the thickness of the base film, and at least one cross-linked resin layer contains particles satisfying the following condition (a): Laminated film.
(A) At least resin particles having an average particle size larger than 0.5 μm and smaller than 1.5 μm are contained in a proportion of more than 5% by mass and 50% by mass or less with respect to each crosslinked resin layer (100% by mass). In the transparent laminated film having a cross-linked resin layer on both sides of the base film,
The total thickness of the cross-linked resin layer is 8% or more of the thickness of the base film, and at least one cross-linked resin layer contains particles satisfying the following condition (b): Laminated film.
(B) containing at least resin particles having an average particle size of 0.1 μm or more and less than 1.5 μm in a proportion of 0.5% by mass or more and 5% by mass or less with respect to each crosslinked resin layer (100% by mass); Inorganic particles having an average particle diameter of 250 nm or less are contained in a proportion of 5% by mass or more and 50% by mass or less with respect to each crosslinked resin layer (100% by mass). The transparent laminated film has a heat shrinkage rate in the vertical direction when heated at 210 ° C. for 10 minutes of 80% or less of the heat shrinkage rate in the vertical direction when the base film is heated under the same conditions. The transparent laminated film according to claim 1 or 2 . The crosslinked resin layer according to claim 1, wherein the polyfunctional acrylate monomer having two or more acryloyl groups or methacryloyl groups in one molecule is a resin layer having a crosslinked structure obtained by crosslinking The transparent laminated film according to any one of the above. The polyfunctional acrylate monomer is an alicyclic polyfunctional acrylate monomer having an alicyclic structure or a polyfunctional urethane acrylate monomer having three or more acryloyl groups or methacryloyl groups in one molecule. Item 5. The transparent laminated film according to Item 4 . The thickness of the said base film is less than 100 micrometers, The transparent laminated film in any one of Claims 1-5 characterized by the above-mentioned. Said substrate film, characterized in that it is a resin film mainly composed of glass transition temperature (Tg) 130 ° C. or less of the resin, the transparent laminate film according to any one of claims 1-6. The transparent laminated film according to any one of claims 1 to 7 , wherein the base film is a film mainly composed of polyethylene terephthalate resin and biaxially stretched. Transparent laminate film according to any one of claims 1-8, wherein the resin particles, characterized in that acrylic particles made of acrylic resin. The transparent laminated film according to any one of claims 2 to 9 , wherein the inorganic particles are silica particles made of silicon oxide (silica). Transparent laminate film according to any one of claims 1-10 to one of the crosslinked resin layer of the laminated film is characterized by containing no particles. Transparent laminate film according to any one of claims 1 to 11, wherein the haze of the laminated film is not more than 3%. A transparent substrate having a transparent laminate film according to any of claims 1 to 12 as a substrate.