KR20180025964A - A resin film, a laminate, an optical member, a display member, and a front plate - Google Patents

Abstract

A resin film (10) containing a polyimide-based polymer is disclosed. When the resin film 10 is subjected to a light irradiation test for irradiating predetermined light from the main surface 10a side,
(i) the resin film after the light irradiation test has a transmittance of 85% or more with respect to light of 550 nm, and
(ii) the resin film before the light irradiation test has a yellowness value of 5 or less, and the difference in yellowness before and after the light irradiation test of the resin film is less than 2.5,
.

Description

A resin film, a laminate, an optical member, a display member, and a front plate

The present invention relates to a resin film, a laminate, an optical member, a display member, and a front plate.

BACKGROUND ART Conventionally, glass has been used as a base material of a display member, a base material of an optical member, and a material of a front plate constituting various display devices such as a solar cell or a display. However, the glass had the drawback of being fragile and heavy. In recent years, the glass substrate or the glass front plate does not have sufficient material properties in terms of thinning, lightening, and flexibility of displays. For this reason, as a material or a substrate replacing glass, an acrylic resin and a laminate imparting scratch resistance to a resin have been studied. Composite materials of an organic material and an inorganic material such as a hybrid film including polyimide and silica have also been studied (see, for example, Patent Documents 1 and 2).

Japanese Unexamined Patent Application Publication No. 2008-163309 U.S. Patent No. 8207256

According to the knowledge of the present inventors, a resin film containing a polyimide-based polymer can achieve excellent flexibility while having high transparency. However, a resin film containing a polyimide-based polymer sometimes causes a change in contrast and hue at the time of bending, and further improvement is required in this respect. The resin film applied to the substrate of the display member of the flexible device, the substrate of the optical member and / or the front plate is required to have good visibility at the time of bending.

Accordingly, a main object of the present invention is to improve the visibility at the time of bending, with respect to a resin film containing a polyimide-based polymer and having high transparency.

The resin film related to one embodiment of the present invention contains a polyimide-based polymer. When a light irradiation test was performed in which the resin film was irradiated with light of 313 nm from the main surface side of one side of the resin film for 24 hours by a light source having an output of 40 W provided at a distance of 5 cm from the resin film, The resin film satisfies the following conditions.

(i) the resin film after the light irradiation test has a transmittance of 85% or more with respect to light of 550 nm, and

(ii) the resin film before the light irradiation test has a yellowness degree of 5 or less, and the difference in yellowness degree of the resin film before and after the light irradiation test is less than 2.5

The resin film satisfying these conditions (i) and (ii) is hard to cause a change in contrast or hue at the time of bending, and good visibility can be maintained.

The present invention provides a laminate having the resin film and a functional layer provided on at least one side of the resin film. The functional layer may be a layer having at least one function selected from the group consisting of ultraviolet ray absorption, tackiness, and a function of developing a hardness on the surface.

The laminate may further include a primer layer provided between the resin film and the functional layer.

The base member and the front plate of the optical member or display member related to an embodiment of the present invention have the resin film or the laminate. When applied to a flexible device, they can contribute to excellent visibility at the time of bending.

According to the present invention, the transparent resin film containing the polyimide-based polymer can improve the visibility at the time of bending.

1 is a cross-sectional view showing an embodiment of a resin film.
2 is a cross-sectional view showing one embodiment of the laminate.
3 is a cross-sectional view showing one embodiment of the laminate.
4 is a schematic cross-sectional view showing one embodiment of the display device.

Hereinafter, preferred embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments. In the drawings, the same or corresponding elements are denoted by the same reference numerals, and redundant explanations may be omitted.

[Resin film]

1 is a cross-sectional view showing one embodiment of a resin film. The resin film 10 shown in Fig. 1 contains a polyimide-based polymer and has a pair of opposed main surfaces 10a and 10b.

When a light irradiation test was performed in which light of 313 nm was irradiated to the resin film 10 from the side of the main surface 10a for 24 hours by a light source with an output of 40 W provided at a distance of 5 cm from the resin film 10, 10) under the following conditions:

(i) the resin film after the light irradiation test has a transmittance of 85% or more with respect to light of 550 nm, and

(ii) the resin film before the light irradiation test has a yellowness value (YI value) of 5 or less, and a difference in yellowness before and after the light irradiation test of the resin film is less than 2.5,

. The resin film satisfying these conditions (i) and (ii) is hard to cause a change in contrast or hue at the time of bending, and good visibility can be maintained.

The resin film satisfying the conditions (i) and (ii) can be easily obtained, for example, by using a polyimide-based polymer having high transparency and incorporating an ultraviolet absorber into the resin film. Specific examples of the polyimide-based polymer having high transparency and ultraviolet absorber will be described later.

The transmittance of the resin film 10 after the light irradiation test with respect to the light of 550 nm is preferably 90% or more, and usually 100% or less and 95% or less. The haze of the resin film 10 after the light irradiation test is preferably 0.9 or less, and may be 0.1 or more. The resin film 10 before the light irradiation test may have a transmittance of 85% or more with respect to the light of 550 nm. The transmittance of the resin film to light with a predetermined wavelength means the ratio of the intensity of light of the same wavelength transmitted through the resin film to the intensity of light of a predetermined wavelength incident on the resin film. The haze can be measured in accordance with JIS K 7105: 1981. The details of the measurement method of the transmittance and the haze will be described in the following embodiments.

The degree of yellowness of the resin film 10 before the light irradiation test is preferably 4 or less, more preferably 3 or less, and may be 0.5 or more. When the yellowness before the light irradiation test is YI ₀ and when the yellowness after the light irradiation is YI ₁ , the difference in yellowness degree (? YI) between before and after the light irradiation test of the resin film is expressed by the formula:? YI = YI ₁ -YI ₀ Lt; / RTI > DELTA YI is preferably 2.3 or less, more preferably 2.0 or less, and may be 0.1 or more. Details of the method for measuring the yellowness degree are described in the following embodiments.

The resin film (10) includes a polyimide-based polymer. In the present specification, the polyimide-based polymer means a polymer having at least one or more repeating structural units represented by formula (PI), formula (a), formula (a ') or formula (b) When the repeating structural unit represented by formula (PI) is the main structural unit of the polyimide-based polymer, it is preferable from the viewpoint of the strength and transparency of the film. The repeating structural unit represented by the formula (PI) is preferably at least 40 mol%, more preferably at least 50 mol%, still more preferably at least 70 mol%, based on the total repeating structural units of the polyimide polymer , Particularly preferably 90 mol% or more, and even more preferably 98 mol%.

G in the formula (PI) represents a tetravalent organic group, and A represents a divalent organic group. G ² in the formula (a) represents a trivalent organic group, and A ² represents a divalent organic group. G ³ in the formula (a ') represents a tetravalent organic group, and A ³ represents a divalent organic group. G ⁴ and A ⁴ in the formula (b) each represent a divalent organic group.

Examples of the organic group of a tetravalent organic group represented by G in the formula (PI) (hereinafter sometimes referred to as an organic group of G) include groups selected from the group consisting of acyclic aliphatic groups, cyclic aliphatic groups and aromatic groups have. The organic group of G is preferably a tetravalent cyclic aliphatic group or a tetravalent aromatic group from the viewpoint of transparency and flexibility of the resin film 10. Examples of the aromatic group include a monocyclic aromatic group, a condensed polycyclic aromatic group, and a non-condensed polycyclic aromatic group having two or more aromatic rings, which are bonded to each other directly or via a bonding group. From the viewpoints of transparency and suppression of coloration of the resin film, the organic group of G is preferably a cyclic aliphatic group, a cyclic aliphatic group having a fluorine-based substituent, a monocyclic aromatic group having a fluorine-based substituent, a condensed polycyclic aromatic group having a fluorine- Lt; RTI ID = 0.0 > polycyclic < / RTI > aromatic group. In the present specification, the fluorine-based substituent means a group containing a fluorine atom. The fluorine-based substituent is preferably a fluoro group (fluorine atom, -F) and a perfluoroalkyl group, more preferably a fluoro group and a trifluoromethyl group.

More specifically, the organic group of G may be, for example, a saturated or unsaturated cycloalkyl group, a saturated or unsaturated heterocycloalkyl group, an aryl group, a heteroaryl group, an arylalkyl group, an alkylaryl group, a heteroalkylaryl group, (Which may be the same) and are connected to each other directly or by a bonding group. Examples of the bonding group include -O-, an alkylene group of 1 to 10 carbon atoms, -SO ₂ -, -CO- or -CO-NR- (R represents an alkyl group having 1 to 3 carbon atoms such as a methyl group, ).

The number of carbon atoms of the tetravalent organic group represented by G is usually 2 to 32, preferably 4 to 15, more preferably 5 to 10, and still more preferably 6 to 8. When the organic group of G is a cyclic aliphatic group or an aromatic group, at least one of the carbon atoms constituting these groups may be substituted with a hetero atom. Examples of the hetero atom include O, N or S.

Specific examples of G include groups represented by the following formulas (20), (21), (22), (23), (24), (25) or (26). The * in the formula represents the binding hand. Z in formula (26) represents a single bond, -O-, -CH ₂ -, -C (CH ₃ ) ₂ -, -Ar-O-Ar-, -Ar-CH ₂ -Ar-, (CH ₃ ) ₂ -Ar- or -Ar-SO ₂ -Ar-. Ar represents an aryl group having 6 to 20 carbon atoms, and may be, for example, a phenylene group. At least one of the hydrogen atoms of these groups may be substituted with a fluorine-based substituent.

In the formula (PI), a bivalent organic group represented by A (hereinafter sometimes referred to as an organic group of A) includes a group selected from the group consisting of a non-cyclic aliphatic group, a cyclic aliphatic group and an aromatic group have. The divalent organic group represented by A is preferably selected from a divalent cyclic aliphatic group and a divalent aromatic group. Examples of the aromatic group include a monocyclic aromatic group, a condensed polycyclic aromatic group, and a non-condensed polycyclic aromatic group having two or more aromatic rings, which are bonded to each other directly or via a bonding group. From the viewpoint of transparency and inhibition of coloring of the resin film, it is preferable that the organic group of A is introduced with a fluorine-based substituent.

More specifically, the organic group of A may be, for example, a saturated or unsaturated cycloalkyl group, a saturated or unsaturated heterocycloalkyl group, an aryl group, a heteroaryl group, an arylalkyl group, an alkylaryl group, a heteroalkylaryl group, (Which may be the same) and are selected from the groups which are directly linked to each other or by a bonding group. Examples of the hetero atom include O, N or S, and examples of the bonding group include -O-, an alkylene group having 1 to 10 carbon atoms, -SO ₂ -, -CO- or -CO-NR- (R represents a methyl group, An alkyl group having 1 to 3 carbon atoms such as a methyl group or a propyl group, or a hydrogen atom).

The number of carbon atoms of the divalent organic group represented by A is usually 2 to 40, preferably 5 to 32, more preferably 12 to 28, and most preferably 24 to 27.

Specific examples of A include groups represented by the following formulas (30), (31), (32), (33) or (34). The * in the formula represents the binding hand. Z ¹ to Z ³ each independently represent a single bond, -O-, -CH ₂ -, -C (CH ₃ ) ₂ -, -SO ₂ -, -CO- or -CO-NR- , An alkyl group having 1 to 3 carbon atoms such as an ethyl group or a propyl group, or a hydrogen atom). In the following group, it is preferable that Z ¹ and Z ² and Z ² and Z ³ are respectively in a meta position or a para position with respect to each ring. It is preferable that the single bond of Z ¹ and the terminal, the single bond of Z ² and the terminal, and the single bond of Z ³ and the terminal are respectively in the meta position or the para position. In one example of A, Z ¹ and Z ³ are -O- and Z ² is -CH ₂ -, -C (CH ₃ ) ₂ - or -SO ₂ -. One or two or more hydrogen atoms of these groups may be substituted with a fluorine-based substituent.

At least one hydrogen atom of the hydrogen atoms constituting at least one of A and G may be substituted with at least one functional group selected from the group consisting of a fluorine-based substituent, a hydroxyl group, a sulfone group and an alkyl group having 1 to 10 carbon atoms. When the organic group of A and the organic group of G are each a cyclic aliphatic group or aromatic group, it is preferable that at least one of A and G has a fluorine-based substituent, more preferably both A and G have a fluorine-based substituent.

G ² in the formula (a) is a trivalent organic group. This organic group can be selected from the same group as the organic group of G in formula (PI) except that it is a trivalent group. As examples of G ² , specific examples of G include groups in which any one of four bonding hands of the groups represented by formulas (20) to (26) is substituted with a hydrogen atom. A ² in the formula (a) can be selected from the same group as A in the formula (PI).

G ³ in the formula (a ') can be selected from the same group as the organic group of G in the formula (PI). A ³ in the formula (a ') can be selected from the same group as A in the formula (PI).

G ⁴ in the formula (b) is a divalent organic group. This organic group can be selected from the same group as the organic group of G in formula (PI) except that it is a divalent group. Examples of G ⁴ include groups in which two of four bonding hands of the groups represented by formulas (20) to (26), which are specific examples of G, are substituted with hydrogen atoms. A ⁴ in the formula (b) can be selected from the same group as A in the formula (PI).

The polyimide-based polymer contained in the resin film (10) can be obtained by reacting a diamine with a tetracarboxylic acid compound (including a tetracarboxylic acid compound such as an acid chloride compound and a tetracarboxylic acid dianhydride) Or a condensation polymer obtained by polycondensation of at least one of tricarboxylic acid compounds (including acid chloride compounds and tricarboxylic acid compound derivatives such as tricarboxylic acid anhydrides). The dicarboxylic acid compound (including a flexible compound such as an acid chloride compound) may be polycondensed. The repeating structural unit represented by the formula (PI) or the formula (a ') is usually derived from a diamine and a tetracarboxylic acid compound. The repeating structural unit represented by the formula (a) is usually derived from a diamine and a tricarboxylic acid compound. The repeating structural unit represented by the formula (b) is usually derived from a diamine and a dicarboxylic acid compound.

Examples of the tetracarboxylic acid compound include aromatic tetracarboxylic acid compounds, alicyclic tetracarboxylic acid compounds and acyclic aliphatic tetracarboxylic acid compounds. These may be used in combination of two or more. The tetracarboxylic acid compound is preferably a tetracarboxylic acid dianhydride, and examples of the tetracarboxylic acid dianhydride include aromatic tetracarboxylic dianhydride, alicyclic tetracarboxylic dianhydride, and acyclic aliphatic tetracarboxylic dianhydride .

From the viewpoints of the solubility of the polyimide-based polymer in a solvent and the transparency and bending property when the resin film 10 is formed, the tetracarboxylic acid compound is preferably selected from an alicyclic tetracarboxylic compound and an aromatic tetracarboxylic acid compound desirable. From the viewpoints of transparency and inhibition of coloration of the resin film, the tetracarboxylic acid compound is preferably selected from an alicyclic tetracarboxylic acid compound having a fluorine-based substituent and an aromatic tetracarboxylic acid compound having a fluorine-based substituent, Type tetracarboxylic acid compound.

Examples of the tricarboxylic acid compound include aromatic tricarboxylic acids, alicyclic tricarboxylic acids, acyclic aliphatic tricarboxylic acids and their flexible acid chloride compounds and acid anhydrides. The tricarboxylic acid compound is preferably selected from aromatic tricarboxylic acids, alicyclic tricarboxylic acids, acyclic aliphatic tricarboxylic acids and their flexible acid chloride compounds. The tricarboxylic acid compound may be used in combination of two or more.

From the viewpoints of the solubility of the polyimide-based polymer in a solvent and the transparency and bending property when the resin film 10 is formed, the tricarboxylic acid compound is preferably selected from an alicyclic tricarboxylic acid compound and an aromatic tricarboxylic acid compound desirable. From the viewpoints of transparency and inhibition of coloring of the resin film, the tricarboxylic acid compound is preferably selected from an alicyclic tricarboxylic acid compound having a fluorine-based substituent and an aromatic tricarboxylic acid compound having a fluorine-based substituent.

Examples of the dicarboxylic acid compound include aromatic dicarboxylic acids, alicyclic dicarboxylic acids, acyclic aliphatic dicarboxylic acids and their flexible acid chloride compounds and acid anhydrides. The dicarboxylic acid compound is preferably selected from aromatic dicarboxylic acids, alicyclic dicarboxylic acids, acyclic aliphatic dicarboxylic acids and their flexible acid chloride compounds. The dicarboxylic acid compound may be used in combination of two or more.

From the viewpoints of the solubility of the polyimide-based polymer in a solvent and the transparency and bending property when the resin film 10 is formed, the dicarboxylic acid compound is preferably selected from an alicyclic dicarboxylic acid compound and an aromatic dicarboxylic acid compound desirable. From the viewpoints of transparency of the resin film and inhibition of coloration, the dicarboxylic acid compound is preferably selected from an alicyclic dicarboxylic acid compound having a fluorine-based substituent and an aromatic dicarboxylic acid compound having a fluorine-based substituent.

Examples of the diamines include aromatic diamines, alicyclic diamines and aliphatic diamines. These may be used in combination of two or more. From the viewpoints of the solubility of the polyimide-based polymer in a solvent and the transparency and bending property when the resin film 10 is formed, the diamines are preferably selected from aromatic diamines having alicyclic diamines and fluorine-based substituents.

When such a polyimide-based polymer is used, it has particularly excellent flexibility and has a high light transmittance (for example, 85% or more, preferably 88% or more, more preferably 88% or more, (For example, 5 or less, preferably 3 or less) and a low haze (for example, 1.5% or less, preferably 1.0% or less).

The polyimide-based polymer may be a copolymer containing a plurality of different repeating structural units different from each other. The weight average molecular weight of the polyimide-based polymer is usually from 10,000 to 500,000. The weight average molecular weight of the polyimide-based polymer is preferably 50,000 to 500,000, and more preferably 70,000 to 400,000. The weight average molecular weight is the standard polystyrene reduced molecular weight measured by gel permeation chromatography (GPC). If the weight average molecular weight of the polyimide-based polymer is high, high flexibility is likely to be obtained. However, if the weight average molecular weight of the polyimide-based polymer is too large, the viscosity of the varnish tends to be high and the workability tends to decrease.

The polyimide-based polymer may contain a halogen atom such as a fluorine atom which can be introduced by the fluorine-based substituent described above. When the polyimide-based polymer contains a halogen atom, the elastic modulus of the resin film can be improved and the yellowness degree can be reduced. As a result, wounds and wrinkles generated in the resin film can be suppressed, and the transparency of the resin film can be improved. The halogen atom is preferably a fluorine atom. The content of the halogen atom in the polyimide-based polymer is preferably 1 to 40 mass%, more preferably 1 to 30 mass%, based on the mass of the polyimide-based polymer.

The resin film (10) may contain one or more ultraviolet absorbers. The ultraviolet absorber can be appropriately selected from what is conventionally used as an ultraviolet absorber in the field of resin materials. The ultraviolet absorber may contain a compound that absorbs light having a wavelength of 400 nm or less. Examples of the ultraviolet absorber that can be suitably combined with the polyimide-based polymer include at least one kind of compound selected from the group consisting of benzophenone-based compounds, salicylate-based compounds, benzotriazole-based compounds and triazine- .

In the present specification, the term "system compound" refers to a derivative of a compound to which the "system compound" is added. For example, the "benzophenone compound" refers to a compound having a substituent bonded to benzophenone and benzophenone as a matrix skeleton.

The blending amount of the ultraviolet absorber may be such that the resin film 10 satisfies the conditions (i) and (ii) described above. Concretely, the amount of the ultraviolet absorber is usually 1% by mass or more, preferably 2% by mass or more, more preferably 3% by mass or more, usually 10% Or less, more preferably 6 mass% or less.

The resin film (10) may further contain an inorganic material such as inorganic particles. The inorganic material is preferably a silicon material containing silicon atoms. When the resin film 10 contains an inorganic material such as a silicon material, particularly excellent effects are obtained in terms of flexibility.

Examples of the silicon material containing a silicon atom include silica particles, quaternary alkoxysilanes such as tetraethyl orthosilicate (TEOS), and silicon compounds such as silsesquioxane derivatives. Among these silicon materials, silica particles are preferable from the viewpoints of transparency and flexibility of the resin film (10).

The average primary particle size of the silica particles is usually 100 nm or less. When the average primary particle size of the silica particles is 100 nm or less, the transparency tends to be improved.

The average primary particle size of the silica particles in the resin film can be obtained by observation with a transmission electron microscope (TEM). The primary particle diameter of the silica particles can be set to a constant diameter by a transmission electron microscope (TEM). The average primary particle diameter can be determined as an average value of 10 primary particle diameters measured by TEM observation. The particle distribution of the silica particles before forming the resin film can be obtained by a commercially available laser diffraction particle size distribution meter.

In the resin film 10, the compounding ratio of the polyimide-based polymer and the inorganic material is preferably 1: 9 to 10: 0, more preferably 3: 7 to 10: 0, More preferably from 3: 7 to 8: 2, and even more preferably from 3: 7 to 7: 3. The ratio of the inorganic material to the total mass of the polyimide-based polymer and the inorganic material is usually 20 mass% or more, preferably 30 mass% or more, and usually 90 mass% or less and 70 mass% or less. When the blending ratio of the polyimide-based polymer and the inorganic material is within the above range, the transparency and the mechanical strength of the resin film tend to be improved.

The resin film (10) may further contain other components as long as it does not significantly impair the transparency and the bending property. Examples of the other components include antioxidants, releasing agents, stabilizers, coloring agents such as bluing agents, flame retardants, lubricants and leveling agents. The proportion of the components other than the polyimide-based polymer and the inorganic material is preferably more than 0% and not more than 20% by mass, more preferably more than 0% and less than 10% by mass with respect to the mass of the resin film (10) to be.

When the resin film 10 contains a polyimide-based polymer and a silicon material, it is preferable that Si / N, which is an atom number ratio of silicon atoms to nitrogen atoms, in at least one main surface 10a is 8 or more. This atomic ratio Si / N is calculated from the abundance of silicon atoms and the abundance of nitrogen atoms obtained by X-ray photoelectron spectroscopy (XPS) to evaluate the composition of the main surface 10a Value.

When the Si / N ratio in the main surface 10a of the resin film 10 is 8 or more, sufficient adhesion with the functional layer 20 described later can be obtained. From the viewpoint of adhesion, Si / N is more preferably 9 or more, or even more preferably 10 or more, more preferably 50 or less, and still more preferably 40 or less.

The thickness of the resin film 10 is appropriately adjusted according to the flexible device to which the laminate 30 is applied, but is preferably 10 to 500 탆, more preferably 15 to 200 탆, and more preferably 20 to 100 탆 More preferable. The resin film 10 having such a constitution has particularly excellent flexibility.

Next, an example of a manufacturing method of the resin film 10 of the present embodiment will be described. The polyimide-based polymer varnish used in the production of the resin film is prepared by dissolving a polyimide-based polymer soluble in a polymerized solvent in a solvent by a known method for synthesizing a polyimide-based polymer. The solvent may be any solvent that dissolves the polyimide-based polymer. Examples of the solvent include dimethylhexacetamide (DMAC), dimethylformamide (DMF), dimethylsulfoxide (DMSO), gamma -butyrolactone And mixed solvents thereof.

In the case of producing a resin film containing an inorganic material, an inorganic material is added to the polyimide-based polymer varnish and stirred and mixed by a known stirring method to prepare a dispersion in which the inorganic material is uniformly dispersed. When an ultraviolet absorber is compounded, an ultraviolet absorber may be added to this dispersion.

The polyimide-based polymer varnish or dispersion may further contain an additive. Examples of additives include antioxidants, releasing agents, stabilizers, coloring agents such as bluing agents, flame retardants, lubricants, thickeners and leveling agents. The polyimide-based polymer varnish or dispersion may contain a compound such as alkoxysilane having one or two or more metal alkoxide groups contributing to binding of the inorganic particles. An example of such a compound is an alkoxysilane having an amino group. By using a polyimide-based polymer varnish or dispersion containing such a compound, the mixing ratio of the inorganic particles can be increased while maintaining optical properties such as transparency of the resin film.

The polyimide-based polymer varnish or dispersion may further contain water. The content of water is usually 0.1 to 10 mass% with respect to the mass of the polyimide-based polymer varnish or dispersion.

The resin film can be produced by an appropriate known method. Examples of the production method include the following methods. The above-mentioned polyimide-based polymer varnish or dispersion is applied to a substrate by a known roll-to-roll or batch method to form a coated film. The coating film is dried to form a film. Thereafter, the film is peeled from the substrate to obtain the resin film 10. Examples of the substrate include a polyethylene terephthalate (PET) substrate, a stainless steel (SUS) belt, a glass substrate, and the like.

The coating film may be heated for drying and / or baking of the coating film. The heating temperature of the coating film is usually 50 to 350 ° C. The coating film may be heated under an inert atmosphere or under reduced pressure. The solvent can be evaporated and removed by heating the coating film. The resin film may be formed by a method including a step of drying the coating film at 50 to 150 占 폚 and a step of baking the coated film at 180 to 350 占 폚.

Subsequently, surface treatment may be performed on at least one main surface of the resin film. The surface treatment is preferably UV ozone treatment. By the UV ozone treatment, Si / N can be easily made 8 or more. However, the method of setting Si / N to 8 or more is not limited to UV ozone treatment. The main surfaces 10a and / or 10b of the resin film 10 may be subjected to a surface treatment such as a plasma treatment or a corona discharge treatment in order to improve adhesion with a functional layer described later.

The UV ozone treatment can be performed using a known ultraviolet light source including a wavelength of 200 nm or less. An example of an ultraviolet light source is a low-pressure mercury lamp. As the ultraviolet light source, various commercially available devices having ultraviolet light sources may be used. As a commercially available apparatus, for example, an ultraviolet (UV) ozone cleaning apparatus UV-208 manufactured by Technovision Co., Ltd. can be mentioned.

The resin film 10 of the present embodiment thus obtained is excellent in flexibility. When Si / N, which is the atomic ratio of silicon atoms to nitrogen atoms, is set to 8 or more on at least one main surface 10a, excellent adhesion with the functional layer 20 described later can be obtained.

[Laminate]

2 is a cross-sectional view showing one embodiment of the laminate. The laminate 30 shown in Fig. 2 is a laminate having a resin film 10 and a functional layer 20 laminated on one main surface 10a of the resin film 10. Fig.

The functional layer 20 may be a layer for imparting the function (performance) to the layered product 30 when the layered product 30 is used as a substrate or a front plate of an optical member or a display member of a flexible device. Here, in the present specification, the optical member means a sensor unit or a signal emitting unit such as a touch sensor in a display device, and a display member means an image display unit such as an organic EL device or a liquid crystal display in the display unit do.

The functional layer 20 is preferably a layer having at least one function selected from the group consisting of ultraviolet ray absorption, function of expressing high hardness on the surface, tackiness, color adjustment, and refractive index adjustment.

The layer (ultraviolet absorbing layer) having a function of absorbing ultraviolet rays as the functional layer 20 is a layer having a function of absorbing ultraviolet rays such as ultraviolet ray absorbing layer and ultraviolet ray absorbing layer which are composed of a main material selected from a transparent resin of ultraviolet curing type, a transparent resin of electron beam curing type, , And an ultraviolet absorber dispersed in the matrix. By providing an ultraviolet absorbing layer as the functional layer 20, the change in yellowness due to light irradiation can be easily suppressed.

The ultraviolet curable, electron beam curable, or thermosetting transparent resin as the main material of the ultraviolet absorbing layer is not particularly limited, but may be, for example, poly (meth) acrylate. The ultraviolet absorber may be selected from the same compounds exemplified as the ultraviolet absorber that can be contained in the resin film 10. [

The ultraviolet absorbing layer may be a layer absorbing 95% or more of light having a wavelength of 400 nm or less (for example, light having a wavelength of 313 nm). In other words, the ultraviolet absorbing layer may be a layer having a transmittance of light having a wavelength of 400 nm or less (for example, light having a wavelength of 313 nm) of less than 5%. The ultraviolet absorbing layer may include an ultraviolet absorbing agent having such a concentration that the transmittance can be obtained. The ratio of the content of the ultraviolet absorbing agent in the ultraviolet absorbing layer (functional layer 20) is usually 1% by mass or less, preferably 1% by mass or less, based on the mass of the ultraviolet absorbing layer, from the viewpoint of suppressing the increase in yellowness of the layered product by light irradiation. By mass, preferably not less than 3% by mass, and usually not more than 10% by mass, preferably not more than 8% by mass.

The layer (hard coat layer) having the function of exhibiting high hardness on the surface as the functional layer 20 is a layer which gives a surface having a pencil hardness higher than the pencil hardness of the surface of the resin film to the layer to be. The hard coat layer is not particularly limited, but includes an ultraviolet curing type, an electron beam curing type or a thermosetting type resin typified by poly (meth) acrylates. The hard coat layer may contain a photopolymerization initiator and an organic solvent. The poly (meth) acrylates include, for example, at least one (meth) acrylate selected from polyurethane (meth) acrylate, epoxy (meth) acrylate and other polyfunctional poly (Meth) acrylate. The hard coat layer may contain inorganic oxides such as silica, alumina, and polyorganosiloxane in addition to the above components.

The layer (adhesive layer) having the adhesive function as the functional layer 20 has a function of adhering the layered product 30 to another member. As a material for forming the adhesive layer, for example, a thermosetting resin composition or a photocurable resin composition can be mentioned.

The adhesive layer may be composed of a resin composition containing a component having a polymerizable functional group. In this case, strong adhesion can be realized by further polymerizing the resin composition constituting the adhesive layer after bringing the laminate 30 into close contact with another member. The adhesive strength between the resin film 10 and the adhesive layer is preferably 0.1 N / cm or more, more preferably 0.5 N / cm or more.

The adhesive layer may contain a thermosetting resin composition or a photocurable resin composition as a material. In this case, the resin composition can be polymerized and cured by supplying energy afterwards.

The adhesive layer may be a layer which is adhered to an object by pressure, which is called Pressure Sensitive Adhesive (PSA). The pressure-sensitive adhesive may be a pressure-sensitive adhesive which is "a substance which is tacky at room temperature and adheres to the adherend with a light pressure" (JIS K6800), and "a specific ingredient is contained in a protective film (microcapsule) (JIS K6800) which can maintain stability until the film is destroyed by heat (pressure, heat, etc.) ".

The layer (color adjusting layer) having the function of color adjustment as the functional layer 20 is a layer capable of adjusting the layered product 30 to a desired color. The color adjusting layer may be, for example, a layer containing a resin and a coloring agent. Examples of the coloring agent include inorganic pigments such as titanium oxide, zinc oxide, spinach, titanium oxide-based fired pigments, family pigments, cobalt aluminate, and carbon black; An organic pigment such as an azo based compound, a quinacridone based compound, an anthraquinone based compound, a perylene based compound, an isoindolinone based compound, a phthalocyanine based compound, a quinophthalone based compound, a threne based compound and a diketopyrrolopyrrole based compound; Extender pigments such as barium sulfate and calcium carbonate; Dyes such as basic dyes, acid dyes and mordant dyes.

The refractive index adjusting layer (refractive index adjusting layer) serving as the functional layer 20 has a refractive index different from that of the resin film 10 and is capable of imparting a predetermined refractive index to the laminate. The refractive index adjustment layer may be, for example, a suitably selected resin, a resin layer containing a pigment, if necessary, or a thin film of metal.

Examples of pigments for adjusting the refractive index include silicon oxide, aluminum oxide, antimony oxide, tin oxide, titanium oxide, zirconium oxide and tantalum oxide. The average particle diameter of the pigment is preferably 0.1 탆 or less. By setting the average particle diameter of the pigment to be not more than 0.1 mu m, it is possible to prevent irregular reflection of light passing through the refractive index adjustment layer, thereby preventing reduction in transparency.

Examples of the metal used for the refractive index adjustment layer include metals such as titanium oxide, tantalum oxide, zirconium oxide, zinc oxide, tin oxide, silicon oxide, indium oxide, titanium oxynitride, titanium nitride, silicon oxynitride, Oxides or metal nitrides.

The functional layer 20 suitably has the above functions depending on the use of the layered product 30. [ The functional layer 20 may be a single layer or a plurality of layers. Each layer may have one function or two or more functions.

The functional layer 20 preferably has a function of developing a high hardness on the surface and a function of absorbing ultraviolet rays. In this case, the functional layer 20 includes a layer having a function of exhibiting high hardness on the surface and a function of absorbing ultraviolet light, a layer having a function of exhibiting high hardness on the surface, and a layer having ultraviolet absorption Multi-layer " or " multi-layer comprising a single layer having a function of exhibiting high hardness on the surface and a function of absorbing ultraviolet rays and a layer having a function of exhibiting high hardness on the surface "

The thickness of the functional layer 20 is appropriately adjusted according to the flexible device to which the laminate 30 is applied, but is preferably 1 to 100 占 퐉, more preferably 2 to 80 占 퐉. The functional layer 20 is typically thinner than the resin film 10.

The layered product 30 can be obtained by forming the functional layer 20 on the main surface 10a of the resin film 10. [ The functional layer 20 can be formed by a known roll-to-roll method or a batch method.

The ultraviolet absorbing layer as the functional layer 20 can be obtained by applying a dispersion liquid containing an ultraviolet absorber and a resin such as a resin in which an ultraviolet absorber is dispersed to the main surface 10a of the resin film 10, , And drying and curing the coating film.

The hard coat layer as the functional layer 20 can be obtained by applying a solution containing a resin for forming a hard coat layer to the main surface 10a of the resin film 10 to form a coating film, And curing it.

The adhesive layer as the functional layer 20 can be obtained by, for example, applying a solution containing a pressure-sensitive adhesive for forming an adhesive layer to the main surface 10a of the resin film 10 to form a coating film, To form a film.

The color adjustment layer as the functional layer 20 can be obtained by forming a dispersion liquid containing a pigment or the like for forming a color adjustment layer and a resin such as a resin in which a pigment or the like is dispersed on the main surface 10a of the resin film 10 To form a coating film, and drying and curing the coating film.

The refractive index adjustment layer as the functional layer 20 can be formed on the main surface 10a of the resin film 10 by using an inorganic particle or the like for forming the refractive index adjustment layer and a resin such as a resin A dispersion liquid is applied to form a coating film, and the coating film is dried and cured.

The functional layer 20 having a function of exhibiting a high hardness on the surface and a function of absorbing ultraviolet light can be formed on the main surface 10a of the resin film 10 by using a UV absorber and a resin such as a resin in which the ultraviolet absorber is dispersed And a resin for forming a hard coat layer to form a coating film, and drying and curing the coating film. The resin forming the main component and the resin forming the hard coat layer may be the same.

The multilayer functional layer including a layer having a function of developing hardness on the surface and a layer having ultraviolet absorption can be formed by the following method.

A coating liquid is applied to the main surface 10a of the resin film 10 by applying a dispersion containing an ultraviolet absorbent and a resin such as a resin in which the ultraviolet absorbent is dispersed to form a coating film and the coating film is dried and cured to form an ultraviolet absorbing layer . Subsequently, a hard coat layer may be formed by applying a solution containing a resin forming the hard coat layer to the ultraviolet absorbing layer to form a coat, and drying and curing the coat. By this method, a multilayered functional layer including a layer having a function of exhibiting high hardness on the surface and a layer having ultraviolet absorption is formed.

A multilayer including a single layer having a function of exhibiting high hardness on the surface and a function of absorbing ultraviolet rays and a layer having a function of exhibiting high hardness on the surface can be formed by the following method.

A coating film is formed on the main surface 10a of the resin film 10 by applying a dispersion containing an ultraviolet absorber, a resin such as a resin in which an ultraviolet absorber is dispersed and a resin forming a hard coat layer, Forming a single layer having a function of exhibiting high hardness on the surface and a function of absorbing ultraviolet rays and applying a solution containing a resin for forming a hard coat layer on the single layer to form a coating film, The hard coat layer may be formed by drying and curing the coating film. By this method, a multilayered functional layer including a layer having a function of exhibiting high hardness on the surface and a layer having a function of absorbing ultraviolet rays and a layer having a function of exhibiting high hardness on the surface is formed.

The laminate 30 of the present embodiment thus obtained is excellent in flexibility. The layered product 30 can have functionalities such as transparency, ultraviolet ray characteristics, and a function of exhibiting high hardness on the surface when it is applied to a substrate or a front plate of an optical member or a display member of a flexible device . The layered product 30 is excellent in adhesion between the resin film 10 and the functional layer 20 when Si / N is not less than 8 on the main surface 10a of the resin film 10. [

3 is a cross-sectional view showing one embodiment of the laminate. The laminate 30 shown in Fig. 3 has a primer layer (not shown) provided between the resin film 10 and the functional layer 20 in addition to the resin film 10 and the functional layer 20 which are the same as the laminate of Fig. 25). The primer layer 25 is laminated on one main surface 10a of the resin film 10. The functional layer 20 is laminated on the main surface 25a opposite to the main surface of the primer layer 25 in contact with the resin film 10. [

It is preferable that the primer layer 25 is a layer formed from a primer and contains a material capable of enhancing adhesion between the resin film 10 and the functional layer 20. [ The compound contained in the primer layer 25 may be chemically bonded to the polyimide-based polymer or silicon material contained in the resin film 10 at the interface.

As the primer, for example, a primer of an ultraviolet curing type, a thermosetting type or a two-curing type epoxy compound can be mentioned. The primer agent may be polyamic acid. These primers are preferable because they enhance the adhesion between the resin film 10 and the functional layer 20.

The primer agent may contain a silane coupling agent. The silane coupling agent may be chemically bonded to the silicon material contained in the resin film 10 by a condensation reaction. The silane coupling agent can be suitably used particularly when the blending ratio of the silicon material contained in the resin film 10 is high.

As the silane coupling agent, a compound having a silicon atom and an alkoxysilyl group having 1 to 3 alkoxy groups covalently bonded to the silicon atom can be given. A compound containing a structure in which two or more alkoxy groups are covalently bonded to a silicon atom is preferable and a compound containing a structure in which three alkoxy groups are covalently bonded to a silicon atom is more preferable. Examples of the alkoxy group include a methoxy group, an ethoxy group, an isopropoxy group, an n-butoxy group, and a t-butoxy group. Among them, a methoxy group and an ethoxy group are preferable because they can increase reactivity with a silicon material.

It is preferable that the silane coupling agent has a substituent having high affinity with the resin film 10 and the functional layer 20. From the viewpoint of affinity with the polyimide-based polymer contained in the resin film 10, the substituent of the silane coupling agent is preferably an epoxy group, an amino group, an ureido group or an isocyanate group. When the functional layer 20 contains (meth) acrylates and the silane coupling agent used for the primer layer 25 has an epoxy group, a methacrylic group, an acrylic group, an amino group or a styryl group, . Among them, a silane coupling agent having a substituent selected from a methacryl group, an acryl group, and an amino group is preferable because it shows a tendency of excellent affinity with the resin film 10 and the functional layer 20.

The thickness of the primer layer 25 is appropriately adjusted according to the functional layer 20, but is preferably 0.01 nm to 20 탆. When a primer agent of an epoxy compound is used, the thickness of the primer layer 25 is preferably 0.01 탆 to 20 탆, more preferably 0.1 탆 to 10 탆. When a silane coupling agent is used, the thickness of the primer layer 25 is preferably 0.1 nm to 1 탆, and more preferably 0.5 nm to 0.1 탆.

The laminate 30 of Fig. 3 is obtained by, for example, applying a solution in which a primer agent is dissolved to a main surface 10a of a resin film 10 to form a coating film, drying and curing the coating film to form a primer layer , And the like. The method of forming the other members is the same as that of the layered body 30 of Fig. The primer layer 25 may be cured simultaneously with the functional layer 20 or may be separately cured before the functional layer 20 is formed.

The resin film and the laminate of this embodiment have high transparency and can maintain excellent visibility at the time of bending. In addition, the resin film and the laminate may have excellent flexibility. When a primer layer is provided between the resin film and the functional layer, the adhesion between the resin film and the functional layer is enhanced. The resin film and the laminate can have functionalities such as transparency, ultraviolet ray characteristics, and a function of exhibiting high hardness on the surface, which are required when applied to a substrate or a front plate of an optical member or a display member of a flexible device .

The constitution of the resin film and the laminate can be appropriately modified. For example, functional layers may be provided on both sides of the resin film. In this case, a primer layer may be formed between each functional layer and the resin film.

[Display device (flexible device)]

4 is a cross-sectional view showing an embodiment of a display device. The display device 100 shown in Fig. 4 has an organic EL device 50, a touch sensor 70, and a front plate 90. Fig. These are usually housed in a housing. Between the organic EL device 50 and the touch sensor 70 and between the touch sensor 70 and the front plate 90 are bonded with an optical adhesive (not shown), for example, Optical Clear Adhesive.

The organic EL device 50 is a display member having the organic EL element 51, the first substrate 55, the second substrate 56, and the sealing material 59.

The organic EL element 51 has a pair of electrodes (a first electrode 52 and a second electrode 53) and a light emitting layer 54. The light emitting layer 54 is disposed between the first electrode 52 and the second electrode 53.

The first electrode 52 is formed of a conductive material having light transmittance. The second electrode 53 may also have light transmittance. As the first electrode 52 and the second electrode 53, known materials can be used.

The light emitting layer 54 can be formed by a known light emitting material constituting the organic EL element. The light emitting material may be either a low molecular compound or a high molecular compound.

When electric power is supplied between the first electrode 52 and the second electrode 53, carriers (electrons and holes) are supplied to the light emitting layer 54, and light is generated in the light emitting layer 54. Light generated in the light emitting layer 54 is emitted to the outside of the organic EL device 50 through the first electrode 52 and the first substrate 55.

The first substrate 55 is formed of a light-transmitting material. The second substrate 56 may have light transmittance. The first substrate 55 and the second substrate 56 are bonded together by a sealing material 59 arranged so as to surround the periphery of the organic EL element. The first substrate 55, the second substrate 56, and the sealing material 59 form a sealing structure for sealing the organic EL element therein. The first substrate 55 and / or the second substrate 56 are often gas barrier materials.

As a material for forming one or both of the first substrate 55 and the second substrate 56, an inorganic material such as glass, or a known transparent resin such as an acrylic resin can be used. As these members, a resin film or a laminate related to the above-described embodiment can be employed.

The first substrate 55 and the second substrate 56, which can adopt the laminate related to the present embodiment, correspond to the substrate of the display member or the gas barrier member in the present embodiment. The organic EL device 50 having the first substrate 55 and the second substrate 56 has excellent flexibility because it employs the resin film or laminate related to the present embodiment.

The touch sensor 70 is an optical member having a touch sensor base material 71 and an element layer 72 having a detection element formed on the touch sensor base material 71.

The touch sensor base material 71 is formed of a material having light transmittance. As the touch sensor substrate 71, an inorganic material such as glass or a known transparent resin such as acrylic resin can be used. As the touch sensor substrate 71, a resin film or a laminate related to the above-described embodiment may be employed.

In the element layer 72, a well-known detecting element composed of a semiconductor element, a wiring, a resistor and the like is formed. As a configuration of the detection element, a configuration realizing a known detection system such as a matrix switch, a resistive film system, or a capacitance system can be adopted.

The touch sensor base 71 capable of employing the laminate related to the present embodiment corresponds to the optical member of the present embodiment. Since the touch sensor 70 having such a touch sensor base 71 adopts the resin film or the laminate according to the present embodiment, the touch sensor 70 is excellent in flexibility.

The front plate 90 is formed of a light-transmitting material. The front plate 90 is located at the outermost layer on the display screen side of the display device and functions as a protective member for protecting the display device. The front plate may be referred to as a window film. As the front plate 90, an inorganic material such as glass or a known transparent resin such as acrylic resin can be used. As the front plate 90, a resin film or a laminate related to the above-described embodiment can be employed. When a laminate is employed as the front plate 90, a laminate is usually arranged in a direction in which the functional layer is located outside the display device.

The front plate 90, which can employ the resin film or the laminate related to the present embodiment, has excellent flexibility because it employs the resin film or laminate according to the present embodiment.

If the display device 100 is one or more constituent members selected from the organic EL device 50, the touch sensor 70, and the front plate 90 and the resin film or the laminate related to the present embodiment is employed, It can have excellent flexibility. That is, the display device 100 may be a flexible device.

The device (flexible device) to which the resin film and the laminate related to this embodiment can be applied is not limited to the display device. For example, a solar cell having a substrate on which a photoelectric conversion element is formed and a front plate provided on the substrate surface. In this case, if a resin film or a laminate related to the present embodiment is employed as a substrate or a front plate of the solar cell, the solar cell can have overall excellent flexibility.

Example

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[Example 1]

The compound represented by the formula (1), the compound represented by the formula (2), the compound represented by the formula (3), the catalyst and the solvent (? -Butyrolactone and dimethylacetamide) were placed in a polymerization vessel purged with nitrogen. The charged amount was 75.0 g of the compound represented by Formula (1), 36.5 g of the compound represented by Formula (2), 76.4 g of the compound represented by Formula (3), 1.5 g of the catalyst, 438.4 g of gamma -butyrolactone and 313.1 g of dimethylacetamide did. The molar ratio of the compound represented by formula (2) to the compound represented by formula (3) is 3: 7, the compound represented by formula (2) and the compound represented by formula (3) , And 1.00: 1.02.

The mixture in the polymerization vessel was stirred to dissolve the raw material in the solvent, and then the mixture was heated to 100 DEG C, then heated to 200 DEG C, and kept warm for 4 hours to polymerize the polyimide. During this heating, water in the liquid was removed. Thereafter, the polyimide was obtained by purification and drying.

Subsequently, a solution of polyimide of γ-butyrolactone adjusted to a concentration of 20 mass%, a dispersion in which silica particles having a solid concentration of 30 mass% were dispersed in γ-butyrolactone, a dimethylacetamide solution of an alkoxysilane having an amino group, Absorbent (TINUVIN (registered trademark) 479, manufactured by BASF), and water were mixed and stirred for 30 minutes. These agitations were carried out in accordance with the method described in U.S. Patent No. 8,207,256B2.

Here, the mass ratio of the silica particles to the polyimide was 60:40, the amount of the alkoxysilane having the amino group was 1.67 parts by mass based on 100 parts by mass of the total of the silica particles and the polyimide, the amount of the triazine-based ultraviolet absorber was changed to silica particles and polyimide , And the amount of water was adjusted to 10 parts by mass with respect to 100 parts by mass of the total of silica particles and polyimide.

The mixed solution was applied to a glass substrate and dried by heating at 50 DEG C for 30 minutes and at 140 DEG C for 10 minutes. Thereafter, the film was peeled off from the glass substrate, and a metal frame was mounted and heated at 210 DEG C for 1 hour to obtain a resin film having a thickness of 80 mu m. The content of the silica particles in this resin film was 60 mass%.

[Example 2 (Laminate)]

A two-part curing type primer (trade name: ARACOAT AP2510, manufactured by Arakawa Chemical Industry Co., Ltd.) was applied as a primer layer to one surface of the resin film produced in Example 1, And cured to form a primer layer having a thickness of 1 mu m.

Subsequently, 47.5 parts by mass of tetrafunctional acrylate (trade name: A-TMMT, manufactured by Shin-Nakamura Chemical Co., Ltd.), 47.5 parts by mass of trifunctional acrylate (trade name: A-TMPT, (Trade name: 8BR-600, manufactured by Taisei Fine Chemical Co., Ltd., 40% by mass product), 3 parts by mass of a triazine-based ultraviolet absorber (TINUVIN (registered trademark) 479, BASF), IRGACURE (registered trademark) 184 , 0.6 parts by mass of a leveling agent (trade name: BYK-350, manufactured by BICKEMI Japan Co., Ltd.), and 107 parts by mass of methyl ethyl ketone was applied to form a coating film. The coating film was dried and cured to form a functional layer as a "functional layer having a function of exhibiting high hardness on the surface and a function of ultraviolet ray absorption" having a thickness of 10 μm to obtain a laminate of Example 2.

[Comparative Example 1]

A resin film having a thickness of 80 占 퐉 was obtained in the same manner as in Example 1 except that a triazine-based ultraviolet absorber was not added to the mixed solution for forming the resin film.

[Comparative Example 2]

Polyimide having a glass transition temperature of 390 占 폚 ("Neopurim" manufactured by Mitsubishi Gas Chemical Co., Ltd.) was prepared. A 20% by mass γ-butyrolactone solution of the polyimide, a dispersion in which silica particles having a solid concentration of 30% by mass were dispersed in γ-butyrolactone, a dimethylacetamide solution of an alkoxysilane having an amino group, and water were mixed , And the mixture was stirred for 30 minutes to obtain a mixed solution. The mass ratio of the silica particles to the polyimide is 55:45, the amount of the alkoxysilane having an amino group is 1.67 parts by mass based on 100 parts by mass of the total of the silica particles and the polyimide, the total amount of the silica particles and the polyimide is 100 parts by mass Parts by mass. Using this mixed solution, a resin film having a thickness of 80 탆 was obtained in the same manner as in Example 1.

(evaluation)

1) Optical properties (Yellowness value (YI value))

The Yellow Index (YI value) of each of the resin films of Examples and Comparative Examples was measured by an ultraviolet visible near infrared spectrophotometer V-670 manufactured by Nippon Bunko K.K. After the background measurement in the absence of the sample, the resin film was set in the sample holder, and the transmittance was measured with respect to the light of 300 to 800 nm to obtain the tristimulus values (X, Y, Z). The YI value was calculated based on the following formula.

YI = 100 x (1.2769X-1.0592Z) / Y

2) Transmittance

The ultraviolet-visible near infrared spectrophotometer V-670 manufactured by Nihon Spectroscopy Co., Ltd. was used to measure the transmittance with respect to the light of 300 to 800 nm, and the transmittance to the light with the wavelength of 550 nm was calculated.

3) Hayes

The resin films of Examples and Comparative Examples were set on a sample holder by means of a fully automatic Hayes computer HGM-2DP manufactured by Suga Test Instruments, and the haze of the resin film was measured.

4) Light irradiation test

The resin films of Examples and Comparative Examples were provided for a light irradiation test using UVCON manufactured by Atras. The light source was UV-B 313 nm, the output was 40 W, and the distance between the resin film and the light source was set at 5 cm. The resin film was irradiated with ultraviolet rays for 24 hours. After irradiation with ultraviolet rays, the optical characteristics (YI value, transmittance) were evaluated as described above.

5) Visibility

The film before the light irradiation test was bent, and the state of appearance such as contrast and color at that time was confirmed, and visibility was judged based on the following criteria.

A: No change in contrast or color is confirmed.

C: Appearance change such as change of contrast and color was confirmed.

Table 1 shows the evaluation results. The resin film of the examples provided in the light irradiation test satisfied the above conditions (i) and (ii), and it was confirmed that the resin film and the laminate having the resin film had high visibility at the time of bending.

10 resin film
20 function layer
25 primer layer
30 laminate (laminate)
50 organic EL device
70 touch sensor
90 front plate
100 display device

Claims (12)

A resin film containing a polyimide-based polymer,
When a light irradiation test was performed in which light of 313 nm was irradiated to the resin film from one side of the resin film for 24 hours by a light source with an output of 40 W provided at a distance of 5 cm from the resin film, :
(i) the resin film after the light irradiation test has a transmittance of 85% or more with respect to light of 550 nm, and
(ii) the resin film before the light irradiation test has a yellowness value of 5 or less, and the difference in yellowness before and after the light irradiation test of the resin film is less than 2.5,
. The method according to claim 1,
Wherein the resin film after the light irradiation test has a haze of 1.0% or less. 3. The method according to claim 1 or 2,
Wherein the resin film further contains an ultraviolet absorber. A laminate having a resin film according to any one of claims 1 to 3 and a functional layer provided on at least one side of the resin film. 5. The method of claim 4,
Wherein the functional layer is a layer having at least one function selected from the group consisting of functions of absorbing ultraviolet rays, tackiness, and exhibiting high hardness on the surface. The method according to claim 4 or 5,
And a primer layer provided between the resin film and the functional layer. An optical member having the resin film according to claim 1 or 2. An optical member having the laminate according to any one of claims 3 to 6. A display member comprising the resin film according to any one of claims 1 to 3. A display member having the laminate according to any one of claims 3 to 6. A front plate having the resin film according to claim 1 or 2. A front plate having a laminate according to any one of claims 3 to 6.

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