JP2015186908A - laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate in which decrease in transmittance caused by disposition of a transparent conductive layer is suppressed and coloring caused by disposition of the transparent conductive layer is suppressed.SOLUTION: The laminate includes the following polymeric piezoelectric film, a high refractive index layer, a low refractive index layer, and a transparent conductive layer, in this order. The polymeric piezoelectric film contains a helical chiral polymer (A) having optical activity and a weight average molecular weight of 50000 to 1000000, and has a crystallization degree of 20% to 80% obtained by a DSC method and an internal haze of 5% or less, in which a product of the crystallization degree and a normalized molecular orientation MORc measured by a microwave transmission type molecular orientation meter in a reference thickness of 50 μm is 40 to 700.

Description

  The present invention relates to a laminate.

In recent years, polymer piezoelectric materials using helical chiral polymers having optical activity (for example, polylactic acid polymers) have been reported.
For example, a polymer piezoelectric material that exhibits a piezoelectric constant of about 10 pC / N at room temperature by stretching a molded product of polylactic acid has been disclosed (for example, see Patent Document 1).

As an apparatus using a polylactic acid-based polymer as a polymer piezoelectric member, for example, a touch input device (touch panel) including a piezoelectric sheet made from polylactic acid has been proposed (see, for example, Patent Documents 2 to 5). ). Since the touch input device (touch panel) can detect not only the two-dimensional position information on the touch panel but also the pressure on the touch panel surface, the operation method of the touch panel can be extended to three dimensions.
Transparent conductive substrates used for touch panels, etc. include conductive metal oxides such as indium tin oxide (ITO) and zinc oxide on glass plates, resin plates, and various thermoplastic polymer film substrates. A material obtained by laminating materials having a high refractive index such as the like is generally used.
In addition, a transparent conductive film in which a transparent conductive layer is combined with a multilayer optical film (for example, see Patent Document 6), a base material made of biaxially stretched polyester, acrylic resin and cyclic polyolefin, an adhesive layer, a high refractive index A laminated film in which a layer, a low refractive index layer, and a transparent conductive thin film layer are laminated in this order is disclosed (for example, see Patent Document 7).

JP-A-5-152638 International Publication No. 2010/143528 International Publication No. 2011/125408 International Publication No. 2012/049969 International Publication No. 2011/138903 JP 2011-098563 A JP 2014-096241 A

However, when a transparent conductive layer such as a metal oxide is laminated on the piezoelectric material, the total light transmittance decreases due to a decrease in the transmittance in the short wavelength range of visible light derived from the reflection and absorption of the transparent conductive layer, and at the same time, yellow Or it may turn brown.
Therefore, the objective of this invention is providing the laminated body by which the fall of the transmittance | permeability by providing a transparent conductive layer was suppressed, and the coloration by providing a transparent conductive layer was suppressed.

[1] A helical chiral polymer (A) having an optical activity of weight average molecular weight of 50,000 to 1,000,000, crystallinity obtained by DSC method of 20% to 80%, and microwave transmission Polymer whose normalized molecular orientation MORc and the crystallinity are 40 to 700 when the reference thickness measured by a type molecular orientation meter is 50 μm and whose internal haze for visible light is 5% or less Piezoelectric film,
A high refractive index layer;
A low refractive index layer;
A transparent conductive layer;
The laminated body which has these in this order.
[2] The refractive index n1 of the high refractive index layer is 1.50 to 2.20, the film thickness d1 of the high refractive index layer is 5 nm to 500 nm, and the refractive index n2 of the low refractive index layer is 1. 30 to 1.60, the film thickness d2 of the low refractive index layer is 5 nm to 500 nm, the refractive index n3 of the transparent conductive layer is 1.85 to 2.35, and the film of the transparent conductive layer The thickness d3 is 5 nm to 200 nm,
n2 <n1 ≦ n3
The laminate according to [1], which satisfies the above.
[3] The refractive index n1 of the high refractive index layer is 1.50 to 1.70, the film thickness d1 of the high refractive index layer is 25 nm to 80 nm, and the refractive index n2 of the low refractive index layer is 1. 40 to 1.50, the film thickness d2 of the low refractive index layer is 10 nm to 80 nm, the refractive index n3 of the transparent conductive layer is 1.85 to 2.35, and the film of the transparent conductive layer The laminate according to [1] or [2], wherein the thickness d3 is 5 nm to 60 nm.
[4] The laminated body according to any one of [1] to [3], wherein a refractive index n1 of the high refractive index layer is 1.53 to 1.62.
[5] The laminate according to any one of [1] to [4], which includes a cured resin layer between the polymer piezoelectric film and the high refractive index layer.
[6] The laminate according to [5], wherein the cured resin layer is at least one of an easily adhesive layer, a hard coat layer, an antistatic layer, and an antiblock layer.
[7] The laminate according to [5] or [6], wherein the cured resin layer includes a three-dimensional cross-linked resin and an active energy ray-cured resin cured by active energy ray irradiation.
[8] The laminate according to any one of [5] to [7], wherein the refractive index of the cured resin layer is 1.45 to 1.55.
[9] The laminate according to any one of [5] to [8], in which the cured resin layer has a refractive index of 1.46 to 1.52.
[10] The laminate according to any one of [1] to [9], wherein the thermal shrinkage rate when heated at 150 ° C. for 30 minutes is 2.0% or less in both the MD direction and the TD direction.
[11] Further, any one of [1] to [10], further including an adhesive layer and a peelable release film in this order on the side opposite to the high refractive index layer as viewed from the polymer piezoelectric film. The laminate according to Item 1.
[12] The laminate according to [11], wherein the acid value of the adhesive layer is 0.01 mgKOH / g to 10 mgKOH / g.
[13] The laminate according to [11] or [12], which has a cured resin layer between the polymer piezoelectric film and the adhesive layer.
[14] The laminate according to any one of [1] to [10], further including a peelable protective film on a side opposite to the high refractive index layer as viewed from the polymer piezoelectric film.
[15] The laminate according to [14], which has a cured resin layer between the polymer piezoelectric film and the peelable protective film.
[16] The polymeric piezoelectric film, the stress at 25 ° C. - piezoelectric constant _{d 14} measured by the charge method is 1 pC / N or more, [1] to laminate according to any one of [15].
[17] Any one of [1] to [16], wherein the helical chiral polymer (A) is a polylactic acid polymer having a main chain containing a repeating unit represented by the following formula (1). The laminated body as described in.

[18] The laminate according to any one of [1] to [17], wherein the helical chiral polymer (A) has an optical purity of 95.00% ee or more.
[19] The laminate according to any one of [1] to [18], wherein the polymer piezoelectric film has a content of the helical chiral polymer (A) of 80% by mass or more.
[20] The stabilizer (B) having a weight average molecular weight of 200 to 60000, wherein the polymer piezoelectric film has one or more functional groups selected from the group consisting of a carbodiimide group, an epoxy group, and an isocyanate group, The laminate according to any one of [1] to [19], comprising 0.01 to 10 parts by mass with respect to 100 parts by mass of the helical chiral polymer (A).

  ADVANTAGE OF THE INVENTION According to this invention, the fall of the transmittance | permeability by providing a transparent conductive layer is suppressed, and the laminated body by which the coloration by providing a transparent conductive layer was suppressed can be provided.

It is sectional drawing which shows the 1st aspect of the laminated body of this invention. It is sectional drawing which shows the 2nd aspect of the laminated body of this invention. It is sectional drawing which shows the 3rd aspect of the laminated body of this invention. It is sectional drawing which shows the 4th aspect of the laminated body of this invention.

Hereinafter, the present embodiment which is an example of the present invention will be described.
In this specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.
Further, in the present specification, “film” is a concept including not only what is generally called “film” but also what is generally called “sheet”.

≪Laminated body≫
The laminate of the present invention has a polymer piezoelectric film, a high refractive index layer, a low refractive index layer, and a transparent conductive layer in this order. The polymer piezoelectric film includes an optically active helical chiral polymer (A) having a weight average molecular weight of 50,000 to 1,000,000, the crystallinity obtained by DSC method is 20% to 80%, and The product of the normalized molecular orientation MORc and the crystallinity when the reference thickness measured with a microwave transmission type molecular orientation meter is 50 μm is 40 to 700, and the internal haze for visible light is 5% or less. is there.
When the laminate of the present invention has the above-described configuration, a decrease in transmittance due to the provision of the transparent conductive layer is suppressed, and coloration due to the provision of the transparent conductive layer is suppressed.
Conventionally, when a transparent conductive layer is used as an electrode pattern for a touch panel, there is a problem that it is difficult to accurately express the color of a display device disposed under the touch panel.
On the other hand, the laminate of the present invention suppresses a decrease in transmittance due to the provision of the transparent conductive layer and suppresses coloration due to the provision of the transparent conductive layer, thereby accurately expressing the color of the display device. It becomes easy.
Further, conventionally, there is a problem that a phenomenon called bone appearance occurs in which a difference in transmittance and color tone occurs between a portion where the electrode pattern exists and a portion where the electrode pattern does not exist, and the electrode pattern is visually recognized.
On the other hand, in the laminate of the present invention, it is difficult for a difference in transmittance and color tone between the portion where the electrode is present and the portion where the electrode is not present.
Moreover, since the transmittance | permeability is high when the laminated body of this invention is used for press detection apparatuses, such as a touch panel, the fall of the contrast of the display image of a display is suppressed.
The high refractive index layer, the low refractive index layer, and the transparent conductive layer formed on the polymer piezoelectric film may be formed only on one side or both sides of the polymer piezoelectric film.

<Polymer piezoelectric film>
As the polymer piezoelectric film (piezoelectric material), a predetermined polymer piezoelectric film containing the helical chiral polymer (A) having optical activity is applied.
[Helical Chiral Polymer with Optical Activity (A)]
The helical chiral polymer (A) is a helical chiral polymer having a weight average molecular weight of 50,000 to 1,000,000 and having optical activity.
Here, the “helical chiral polymer having optical activity” refers to a polymer having a helical structure and a molecular optical activity.
The helical chiral polymer (A) is a polymer having a weight average molecular weight of 50,000 to 1,000,000 among the above-mentioned “helical chiral polymers having optical activity”.

Examples of the helical chiral polymer (A) include polypeptides, cellulose derivatives, polylactic acid polymers, polypropylene oxide, poly (β-hydroxybutyric acid), and the like.
Examples of the polypeptide include poly (glutaric acid γ-benzyl), poly (glutaric acid γ-methyl), and the like.
Examples of the cellulose derivative include cellulose acetate and cyanoethyl cellulose.

  The helical chiral polymer (A) preferably has an optical purity of 95.00% ee or more, more preferably 96.00% ee or more, from the viewpoint of improving the piezoelectricity of the polymer piezoelectric film. More preferably, it is 99.00% ee or more, and even more preferably 99.99% ee or more. Desirably, it is 100.00% ee. By setting the optical purity of the helical chiral polymer (A) within the above range, the packing property of the polymer crystal that exhibits piezoelectricity is enhanced, and as a result, the piezoelectricity is considered to be enhanced.

Here, the optical purity of the helical chiral polymer (A) is a value calculated by the following formula.
Optical purity (% ee) = 100 × | L body weight−D body weight | / (L body weight + D body weight)
That is, the optical purity of the helical chiral polymer (A) is
“The amount difference (absolute value) between the amount of L-form (mass%) of helical chiral polymer (A) and the amount of D-form (mass%) of helical chiral polymer (A)” (absolute value) ” Multiply by (100) the value divided by (the total amount of (A) L-form [mass%] and helical chiral polymer (A) D-form [mass%]] ". (Multiplied).

  The amount of L-form [mass%] of the helical chiral polymer (A) and the amount of D-form [mass%] of the helical chiral polymer (A) are obtained by a method using high performance liquid chromatography (HPLC). Use the value obtained. Details of the specific measurement will be described later.

  The helical chiral polymer (A) is preferably a polymer having a main chain containing a repeating unit represented by the following formula (1) from the viewpoint of increasing optical purity and improving piezoelectricity.

Examples of the polymer having the repeating unit represented by the formula (1) as a main chain include polylactic acid-based polymers.
Here, the polylactic acid polymer is “polylactic acid (polymer consisting only of repeating units derived from a monomer selected from L-lactic acid and D-lactic acid)”, “L-lactic acid or D-lactic acid, and L -A copolymer of a compound copolymerizable with lactic acid or D-lactic acid ", or a mixture of both.
Among the polylactic acid polymers, polylactic acid is preferable, and L-lactic acid homopolymer (PLLA) or D-lactic acid homopolymer (PDLA) is most preferable.

Polylactic acid is a polymer in which lactic acid is polymerized by an ester bond and connected for a long time.
It is known that polylactic acid can be produced by a lactide method via lactide; a direct polymerization method in which lactic acid is heated in a solvent under reduced pressure and polymerized while removing water.
As polylactic acid, homopolymer of L-lactic acid, homopolymer of D-lactic acid, block copolymer containing at least one polymer of L-lactic acid and D-lactic acid, and at least one of L-lactic acid and D-lactic acid A graft copolymer containing a polymer may be mentioned.

  Examples of the “compound copolymerizable with L-lactic acid or D-lactic acid” include glycolic acid, dimethyl glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxypropanoic acid, 3-hydroxypropanoic acid, 2- Hydroxyvaleric acid, 3-hydroxyvaleric acid, 4-hydroxyvaleric acid, 5-hydroxyvaleric acid, 2-hydroxycaproic acid, 3-hydroxycaproic acid, 4-hydroxycaproic acid, 5-hydroxycaproic acid, 6-hydroxycaprone Acids, hydroxycarboxylic acids such as 6-hydroxymethylcaproic acid and mandelic acid; cyclic esters such as glycolide, β-methyl-δ-valerolactone, γ-valerolactone and ε-caprolactone; oxalic acid, malonic acid, succinic acid, Glutaric acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, un Polyvalent carboxylic acids such as candioic acid, dodecanedioic acid, terephthalic acid and the like; ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butane Diol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, neopentyl Polyhydric alcohols such as glycol, tetramethylene glycol and 1,4-hexanedimethanol; polysaccharides such as cellulose; aminocarboxylic acids such as α-amino acids;

  The “copolymer of L-lactic acid or D-lactic acid and a compound copolymerizable with the L-lactic acid or D-lactic acid” includes a block copolymer or a graft copolymer having a polylactic acid sequence capable of forming a helical crystal. Can be mentioned.

The concentration of the structure derived from the copolymer component in the helical chiral polymer (A) is preferably 20 mol% or less.
For example, when the helical chiral polymer (A) is a polylactic acid-based polymer, the structure derived from lactic acid and the structure derived from a compound copolymerizable with lactic acid (copolymer component) in the polylactic acid-based polymer It is preferable that the concentration of the structure derived from the copolymer component is 20 mol% or less with respect to the total number of moles.

  Polylactic acid polymers are obtained by, for example, direct dehydration condensation of lactic acid described in JP-A-59-096123 and JP-A-7-033861; US Pat. No. 2,668,182 and A method of ring-opening polymerization using lactide, which is a cyclic dimer of lactic acid, as described in US Pat. No. 4,057,357.

  Furthermore, the polylactic acid polymer obtained by the above production methods has an optical purity of 95.00% ee or higher. For example, when polylactic acid is produced by the lactide method, the optical purity is improved by crystallization operation. It is preferable to polymerize lactide having an optical purity of 95.00% ee or higher.

-Weight average molecular weight-
The weight average molecular weight (Mw) of the helical chiral polymer (A) is 50,000 to 1,000,000 as described above.
When Mw of the helical chiral polymer (A) is 50,000 or more, the mechanical strength of the polymer piezoelectric film is improved. The Mw is preferably 100,000 or more, and more preferably 200,000 or more.
On the other hand, when the Mw of the helical chiral polymer (A) is 1,000,000 or less, the moldability when a polymer piezoelectric film is obtained by molding (for example, extrusion molding) is improved. The Mw is preferably 800,000 or less, and more preferably 300,000 or less.

  Further, the molecular weight distribution (Mw / Mn) of the helical chiral polymer (A) is preferably 1.1 to 5 and more preferably 1.2 to 4 from the viewpoint of the strength of the polymer piezoelectric film. preferable. Furthermore, it is preferable that it is 1.4-3.

  In addition, the weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of helical chiral polymer (A) point out the value measured by the following GPC measuring method using gel permeation chromatograph (GPC). Here, Mn is the number average molecular weight of the helical chiral polymer (A).

-GPC measuring device-
Waters GPC-100
-Column-
Made by Showa Denko KK, Shodex LF-804
-Sample preparation-
The helical chiral polymer (A) is dissolved in a solvent (for example, chloroform) at 40 ° C. to prepare a sample solution having a concentration of 1 mg / mL.
-Measurement conditions-
0.1 ml of the sample solution is introduced into the column at a solvent [chloroform], a temperature of 40 ° C., and a flow rate of 1 ml / min.

  The sample concentration in the sample solution separated by the column is measured with a differential refractometer. A universal calibration curve is created with a polystyrene standard sample, and the weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of the helical chiral polymer (A) are calculated.

Commercially available polylactic acid can be used as the polylactic acid polymer that is an example of the helical chiral polymer (A).
Examples of commercially available products, PURAC Co. PURASORB (PD, PL), manufactured by Mitsui Chemicals, Inc. of LACEA (H-100, H- 400), NatureWorks LLC Corp. ^Ingeo TM Biopolymer, and the like.
When using a polylactic acid polymer as the helical chiral polymer (A), in order to make the weight average molecular weight (Mw) of the polylactic acid polymer 50,000 or more, the polylactic acid is obtained by the lactide method or the direct polymerization method. It is preferable to produce a polymer.

The polymer piezoelectric film may contain only one kind of the above-described helical chiral polymer (A), or may contain two or more kinds.
The content of the helical chiral polymer (A) in the polymer piezoelectric film (the total content in the case of two or more) is from the viewpoint of more effectively achieving the effects of the present invention. 80 mass% or more is preferable with respect to the whole quantity.

[Stabilizer]
The polymer piezoelectric film further includes a stabilizer (B) having a weight average molecular weight of 200 to 60000 having one or more functional groups selected from the group consisting of a carbodiimide group, an epoxy group, and an isocyanate group in one molecule. It is preferable to contain. Thereby, heat-and-moisture resistance can be improved more.

  As the stabilizer (B), “stabilizer (B)” described in paragraphs 0039 to 0055 of International Publication No. 2013/054918 pamphlet can be used.

Examples of the compound containing a carbodiimide group (carbodiimide compound) that can be used as the stabilizer (B) include a monocarbodiimide compound, a polycarbodiimide compound, and a cyclic carbodiimide compound.
As the monocarbodiimide compound, dicyclohexylcarbodiimide, bis-2,6-diisopropylphenylcarbodiimide, and the like are preferable.
Moreover, as a polycarbodiimide compound, what was manufactured by the various method can be used. Conventional methods for producing polycarbodiimides (for example, U.S. Pat. No. 2,941,956, JP-B-47-33279, J.0rg.Chem.28, 2069-2075 (1963), Chemical Review 1981, Vol. 81 No. 1). 4, p619-621) can be used. Specifically, a carbodiimide compound described in Japanese Patent No. 4084953 can also be used.
Examples of the polycarbodiimide compound include poly (4,4′-dicyclohexylmethanecarbodiimide), poly (N, N′-di-2,6-diisopropylphenylcarbodiimide), poly (1,3,5-triisopropylphenylene-2, 4-carbodiimide and the like.
The cyclic carbodiimide compound can be synthesized based on the method described in JP2011-256337A.
Commercially available products may be used as the carbodiimide compound, for example, manufactured by Tokyo Chemical Industry, B2756 (trade name), manufactured by Nisshinbo Chemical Co., Ltd., Carbodilite LA-1, manufactured by Rhein Chemie, Stabaxol P, Stabaxol P400, Stabaxol I (all Product name).

  Examples of the compound (isocyanate compound) containing an isocyanate group in one molecule that can be used as the stabilizer (B) include 3- (triethoxysilyl) propyl isocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate. Diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, 2,2′-diphenylmethane diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, Etc.

  Examples of the compound (epoxy compound) containing an epoxy group in one molecule that can be used as the stabilizer (B) include phenyl glycidyl ether, diethylene glycol diglycidyl ether, bisphenol A-diglycidyl ether, hydrogenated bisphenol A-diglycidyl ether. Phenol novolac type epoxy resin, cresol novolac type epoxy resin, epoxidized polybutadiene and the like.

As described above, the weight average molecular weight of the stabilizer (B) is 200 to 60000, more preferably 200 to 30000, and still more preferably 300 to 18000.
When the molecular weight is within the above range, the stabilizer (B) is more easily moved, and the effect of improving heat and moisture resistance is more effectively exhibited.
The weight average molecular weight of the stabilizer (B) is particularly preferably 200 to 900. In addition, the weight average molecular weight 200-900 substantially corresponds with the number average molecular weight 200-900. Further, when the weight average molecular weight is 200 to 900, the molecular weight distribution may be 1.0. In this case, “weight average molecular weight 200 to 900” can be simply referred to as “molecular weight 200 to 900”. .

When the polymer piezoelectric film contains the stabilizer (B), the polymer piezoelectric film may contain only one kind of stabilizer or two or more kinds.
When the polymeric piezoelectric film contains the stabilizer (B), the content of the stabilizer (B) is 0.01 parts by mass to 10 parts by mass with respect to 100 parts by mass of the helical chiral polymer (A). It is preferably 0.01 parts by mass to 5 parts by mass, more preferably 0.1 parts by mass to 3 parts by mass, and particularly preferably 0.5 parts by mass to 2 parts by mass. preferable.
When the content is 0.01 parts by mass or more, the heat and humidity resistance is further improved.
Moreover, the transparency fall is suppressed more as the said content is 10 mass parts or less.

A preferred embodiment of the stabilizer (B) is a stabilizer having one or more functional groups selected from the group consisting of a carbodiimide group, an epoxy group, and an isocyanate group, and having a number average molecular weight of 200 to 900. (B1) and a stabilizer having two or more functional groups selected from the group consisting of a carbodiimide group, an epoxy group, and an isocyanate group in one molecule, and having a weight average molecular weight of 1000 to 60000 ( A mode in which B2) is used in combination is exemplified. The weight average molecular weight of the stabilizer (B1) having a number average molecular weight of 200 to 900 is about 200 to 900, and the number average molecular weight and the weight average molecular weight of the stabilizer (B1) are almost the same value. .
When the stabilizer (B1) and the stabilizer (B2) are used in combination as the stabilizer, it is preferable that a large amount of the stabilizer (B1) is contained from the viewpoint of improving the transparency.
Specifically, it is preferable that the stabilizer (B2) is in the range of 10 parts by mass to 150 parts by mass with respect to 100 parts by mass of the stabilizer (B1) from the viewpoint of achieving both transparency and wet heat resistance. More preferably, it is in the range of 50 to 100 parts by mass.

  Hereinafter, specific examples (stabilizers B-1 to B-3) of the stabilizer (B) are shown.

Hereinafter, with respect to the stabilizers B-1 to B-3, compound names, commercial products, and the like are shown.
Stabilizer B-1 The compound name is bis-2,6-diisopropylphenylcarbodiimide. The weight average molecular weight (in this example, simply equal to “molecular weight”) is 363. Commercially available products include “Stabaxol I” manufactured by Rhein Chemie and “B2756” manufactured by Tokyo Chemical Industry.
Stabilizer B-2 The compound name is poly (4,4′-dicyclohexylmethanecarbodiimide). As a commercially available product, “Carbodilite LA-1” manufactured by Nisshinbo Chemical Co., Ltd. may be mentioned as having a weight average molecular weight of about 2000.
Stabilizer B-3 The compound name is poly (1,3,5-triisopropylphenylene-2,4-carbodiimide). As a commercially available product, “Stabaxol P” manufactured by Rhein Chemie Co., Ltd. can be mentioned as having a weight average molecular weight of about 3000. Further, “Stabaxol P400” manufactured by Rhein Chemie is listed as having a weight average molecular weight of 20,000.

<Other ingredients>
The polymer piezoelectric film may contain other components as necessary.
Other components include known resins such as polyvinylidene fluoride, polyethylene resin and polystyrene resin; known inorganic fillers such as silica, hydroxyapatite and montmorillonite; known crystal nucleating agents such as phthalocyanine; other than stabilizer (B) And the like.
Examples of the inorganic filler and the crystal nucleating agent include components described in paragraphs 0057 to 0058 of International Publication No. 2013/054918.

<Physical properties of polymer piezoelectric film>
Polymeric piezoelectric film, it piezoelectric constant is large (preferably, the stress at 25 ° C. - that the piezoelectric constant d ₁₄ is 1 pC / N or more as measured by a charge method) is preferred. Furthermore, the polymer piezoelectric film is preferably excellent in transparency and longitudinal tear strength (that is, tear strength in a specific direction; the same applies hereinafter).

[Piezoelectric constant (stress-charge method)]
The piezoelectric constant of the polymer piezoelectric film is a value measured as follows.
First, the polymer piezoelectric film is cut to 150 mm in the direction of 45 ° with respect to the stretching direction (for example, MD direction) of the polymer piezoelectric film and 50 mm in the direction orthogonal to the direction of 45 °, and a rectangular test piece is formed. Make it. Next, the test piece obtained on the test stand of Showa vacuum SIP-600 is set, and Al is vapor-deposited on one surface of the test piece so that the deposition thickness of Al is about 50 nm. Next, Al is vapor-deposited in the same manner on the other surface of the test piece. As described above, an Al conductive layer is formed on both sides of the test piece.

  A direction in which a test piece of 150 mm × 50 mm (polymer piezoelectric film) having an Al conductive layer formed on both sides is formed by 45 ° with respect to the stretching direction (for example, MD direction) of the polymer piezoelectric film by 120 mm and 45 °. A rectangular film of 120 mm × 10 mm is cut out to 10 mm in a direction perpendicular to the film. This is a piezoelectric constant measurement sample.

The obtained sample is set in a tensile tester (manufactured by AND, TENSILON RTG-1250) with a distance between chucks of 70 mm so as not to be loosened. A force is periodically applied so that the applied force reciprocates between 4N and 9N at a crosshead speed of 5 mm / min. At this time, in order to measure the amount of electric charge generated in the sample according to the applied force, a capacitor having a capacitance Qm (F) is connected in parallel to the sample, and the voltage Vm between terminals of the capacitor Cm (95 nF) is converted into a buffer amplifier. Measure through. The generated charge amount Q (C) is calculated as the product of the capacitor capacitance Cm and the terminal voltage Vm. Piezoelectric constant d ₁₄ is calculated by the following equation.
d ₁₄ = (2 × t) / L × Cm · ΔVm / ΔF
t: Sample thickness (m)
L: Distance between chucks (m)
Cm: Capacitor capacity in parallel (F)
ΔVm / ΔF: Ratio of change in voltage between capacitor terminals to change in force

The higher the piezoelectric constant, the greater the displacement of the film relative to the voltage applied to the polymer piezoelectric film, and conversely the greater the voltage generated for the force applied to the polymer piezoelectric film. It is useful as a piezoelectric film.
Specifically, the stress at 25 ° C. - piezoelectric constant _{d 14} measured by the charge method is preferably more than 1 pC / N, more preferably at least pC / N, more preferably more than 4Pc / N. In addition, the upper limit of the piezoelectric constant is not particularly limited, but from the viewpoint of balance such as transparency described later, in the case of a polymer piezoelectric film using a helical chiral polymer (optically active polymer) having optical activity, 50 pC / N The following is preferable, and 30 pC / N or less is more preferable.
Similarly, from the viewpoint of balance with transparency, the piezoelectric constant d14 measured by the resonance method is preferably ₁₅ pC / N or less.

  In the present specification, the “MD direction” is the direction in which the film flows (Machine Direction), that is, the stretching direction, and the “TD direction” is orthogonal to the MD direction and parallel to the main surface of the film. Transverse direction.

[Transparency (internal haze)]
The transparency of the polymer piezoelectric film can be evaluated by measuring internal haze.
The polymer piezoelectric film has an internal haze with respect to visible light of 5% or less. Further, the internal haze of the polymer piezoelectric film is preferably 2.0% or less, and more preferably 1.0% or less, from the viewpoint of further improving transparency and longitudinal crack strength. The lower limit value of the internal haze of the polymer piezoelectric film is not particularly limited, and examples of the lower limit value include 0.01%.
Here, the internal haze of the polymer piezoelectric film refers to the haze excluding the haze due to the shape of the outer surface of the polymer piezoelectric film.
The internal haze of the polymer piezoelectric film was measured according to JIS-K7105 with respect to the polymer piezoelectric film having a thickness of 0.03 mm to 0.05 mm [TC Density Co., Ltd., TC- HIII DPK] is a value measured at 25 ° C., and details of the measuring method will be described in detail in Examples.

[Standardized molecular orientation MORc]
The normalized molecular orientation MORc is a value determined based on the “molecular orientation degree MOR” which is an index indicating the degree of orientation of the helical chiral polymer (A).
Here, the molecular orientation degree MOR (Molecular Orientation Ratio) is measured by the following microwave measurement method. That is, a polymer piezoelectric film (for example, a film-shaped polymer piezoelectric material) is placed in a microwave resonant waveguide of a well-known microwave molecular orientation measuring device (also referred to as a microwave transmission type molecular orientation meter). It arrange | positions so that the surface (film surface) of a polymeric piezoelectric film may become perpendicular | vertical to the advancing direction of a wave. Then, in a state where the sample is continuously irradiated with the microwave whose vibration direction is biased in one direction, the polymer piezoelectric film is rotated 0 to 360 ° in a plane perpendicular to the traveling direction of the microwave, and the sample is transmitted. The degree of molecular orientation MOR is obtained by measuring the measured microwave intensity.

The normalized molecular orientation MORc is a molecular orientation degree MOR when the reference thickness tc is 50 μm, and can be obtained by the following formula.
MORc = (tc / t) × (MOR-1) +1
(Tc: reference thickness to be corrected, t: thickness of polymer piezoelectric film)
The normalized molecular orientation MORc can be measured with a known molecular orientation meter such as a microwave molecular orientation meter MOA-2012A or MOA-6000 manufactured by Oji Scientific Instruments Co., Ltd., at a resonance frequency in the vicinity of 4 GHz or 12 GHz.

The polymer piezoelectric film preferably has a normalized molecular orientation MORc of 1.0 to 15.0, more preferably 2.0 to 10.0, and 4.0 to 10.0. Further preferred.
If the normalized molecular orientation MORc is 1.0 or more, there are many optically active polymer molecular chains (for example, polylactic acid molecular chains) arranged in the stretching direction, and as a result, the rate of formation of oriented crystals increases. High piezoelectricity can be expressed.
If the normalized molecular orientation MORc is 15.0 or less, the longitudinal crack strength is further improved.
Moreover, from the viewpoint of further improving the adhesion between the polymer piezoelectric film and the intermediate layer, the normalized molecular orientation MORc is preferably 7.0 or less.

  For example, when the polymer piezoelectric film is a stretched film, the normalized molecular orientation MORc is controlled by the heat treatment conditions (heating temperature and heating time) before stretching, the stretching conditions (stretching temperature and stretching speed), and the like. sell.

The normalized molecular orientation MORc can be converted into a birefringence Δn obtained by dividing the retardation amount (retardation) by the thickness of the film. Specifically, retardation can be measured using RETS100 manufactured by Otsuka Electronics Co., Ltd. MORc and Δn are approximately in a linear proportional relationship, and when Δn is 0, MORc is 1.
For example, when the helical chiral polymer (A) is a polylactic acid polymer and the birefringence Δn of the polymer piezoelectric film is measured at a measurement wavelength of 550 nm, it is the lower limit of the preferred range of the normalized molecular orientation MORc. 2.0 can be converted to birefringence Δn 0.005. Further, 40, which is the lower limit of the preferred range of the product of the normalized molecular orientation MORc and crystallinity of the polymer piezoelectric film described later, is the product of the birefringence Δn and crystallinity of the polymer piezoelectric film of 0.1 Can be converted to

[Crystallinity]
The crystallinity of the polymer piezoelectric film is determined by the DSC method.
The degree of crystallinity of the polymer piezoelectric film according to the present invention is 20% to 80%. When the degree of crystallinity is 20% or more, the piezoelectricity of the polymer piezoelectric film is maintained high. When the degree of crystallinity is 80% or less, the transparency of the polymer piezoelectric film is maintained high, and when the degree of crystallinity is 80% or less, whitening and breakage hardly occur during stretching. Easy to manufacture piezoelectric film.
Therefore, the crystallinity of the polymer piezoelectric film is 20% to 80%, but the crystallinity is preferably 25% to 70%, more preferably 30% to 50%.

[Product of normalized molecular orientation MORc and crystallinity]
The product of the normalized molecular orientation MORc and the crystallinity of the polymer piezoelectric film is 40 to 700, preferably 75 to 680, more preferably 90 to 660, still more preferably 125 to 650, and particularly preferably 150 to 350. It is. When the above product is in the range of 40 to 700, the polymer piezoelectric film has a good balance between the piezoelectricity and transparency, and has high dimensional stability, and can be suitably used as a piezoelectric element described later.
In the polymer piezoelectric film according to the present invention, for example, the product can be adjusted to the above range by adjusting the crystallization and stretching conditions when the polymer piezoelectric film is produced.

[Shape and film thickness]
Although there is no restriction | limiting in particular in the shape of a polymeric piezoelectric film, A film shape is preferable.
The film thickness of the polymer piezoelectric film (for example, the film thickness of the polymer piezoelectric film in the case of a film shape) is not particularly limited, but is preferably 10 μm to 400 μm, more preferably 20 μm to 200 μm, and more preferably 20 μm to 100 μm. Is more preferable, and 20 μm to 80 μm is particularly preferable. However, when the polymer piezoelectric film is a multilayer film composed of a plurality of layers, the film thickness represents the thickness of the entire multilayer film.

<High refractive index layer>
〔material〕
The material of the high refractive index layer is not particularly limited as long as it can adjust the optical properties (for example, transmittance, color, bone appearance) of the laminate, and the refractive index deviates from a specific range. As long as the object of the present embodiment is not impaired, a conventionally known material can be used. For example, inorganic materials such as metals and metal oxides; organic materials such as resins; organic / inorganic composite compositions containing resins and metal oxide fine particles;
Examples of the inorganic substance include metal oxides such as zinc oxide, titanium oxide, cerium oxide, aluminum oxide, silane oxide, tantalum oxide, yttrium oxide, ytterbium oxide, zirconium oxide, indium tin oxide, and antimony tin oxide. Of these, zirconium oxide, titanium oxide, indium tin oxide, antimony tin oxide, and cerium oxide are preferable, and zirconium oxide is most preferable from the viewpoints of refractive index, electrical insulation, light resistance, and the like. These inorganic substances may be used alone or in combination of two or more.
Examples of the metal include at least one selected from Al, Si, Ti, V, Cr, Fe, Co, Ni, Cu, Zn, In, Sn, W, Ag, Au, Pd, Pt, Sb, Ta, and Zr. Or an alloy thereof.
Examples of the metal oxide and metal oxide fine particles include titanium oxide, zirconium oxide, zinc oxide, niobium oxide, antimony oxide, tin oxide, indium oxide, cerium oxide, aluminum oxide, silicon oxide, magnesium oxide, yttrium oxide, and oxide. Examples thereof include ytterbium, tantalum oxide, and composite oxides thereof. These metal oxides and metal oxide fine particles may be used alone or in combination of two or more.
The average primary particle size of the metal oxide fine particles is preferably from 1 nm to 500 nm, more preferably from 5 nm to 300 nm, and still more preferably from 10 nm to 200 nm, from the viewpoint of transparency. Scattering of visible light is suppressed when it is 500 nm or less, and secondary aggregation of fine particles is suppressed when it is 1 nm or more, which is desirable from the viewpoint of maintaining transparency.
The resin (organic substance) is not particularly limited, and examples thereof include acrylic compounds, methacrylic compounds, vinyl compounds, allyl compounds, urethane compounds, epoxy compounds, epoxide compounds, glycidyl compounds, oxetanes. A compound containing at least one selected from the group consisting of a compound, a melamine compound, a cellulose compound, an ester compound, a silane compound, a silicone compound, a siloxane compound, a silica-acrylic hybrid compound, and a silica-epoxy hybrid compound It is preferable.
As the resin, a cured product obtained by curing with temperature or active energy rays can also be used.

  The method for forming the high refractive index layer is not particularly limited, and for example, a vapor deposition method, a sputtering method, an ion plating method, a chemical vapor deposition (CVD) method, a dry coating method such as a plating method, a wet coating method, or the like can be employed. . Among these, the vapor deposition method and the sputtering method are preferable from the viewpoint of easy control of the layer thickness.

[Refractive index]
The refractive index n1 of the high refractive index layer is preferably 1.50 to 2.20, more preferably 1.50 to 1.70, and more preferably 1.53 to 1.70 from the viewpoint of suppressing a decrease in transmittance and coloration. 62 is more preferable.
Further, the refractive index n1 of the high refractive index layer is larger than the refractive index n2 of the low refractive index layer described later and less than or equal to the refractive index n3 of the transparent conductive layer described later from the viewpoint of suppressing the decrease in transmittance and coloration. That is, it is preferable to satisfy n2 <n1 ≦ n3.
As means for setting the refractive index n1 of the high refractive index layer within the above range, the types and ratios of materials (metal, metal oxide, resin, metal oxide fine particles, additives, etc.) contained in the high refractive index layer And a method for selecting the production conditions (temperature, time, pressure, etc.) of the high refractive index layer.

[Measurement method of refractive index]
A method for measuring the refractive index n1 of the high refractive index layer will be described in detail in Examples.

[Film thickness]
The film thickness d1 of the high refractive index layer is preferably 5 nm to 500 nm, more preferably 10 nm to 200 nm, and even more preferably 25 to 80 nm from the viewpoint of suppressing the decrease in transmittance and coloration.

  The film thickness d1 of the high refractive index layer is measured as follows. A laminate including a high refractive index layer is cut out to a size of 1 mm × 10 mm and embedded in an epoxy resin for an electron microscope. This is fixed to an ultramicrotome sample holder, and a cross-sectional thin section parallel to the short side of the embedded sample piece is prepared. Next, in a section where the thin film of this section is not significantly damaged, a transmission electron microscope (manufactured by JEOL, JEM-2010) is used to obtain a photograph at an acceleration voltage of 200 kV and a bright field at an observation magnification of 10,000 times. The film thickness is obtained from the photograph taken.

  Note that a plurality of high refractive index layers may be provided. In that case, the film thickness of the high refractive index layer is the total thickness of the high refractive index layer. When a plurality of high refractive index layers are provided, the refractive index n1 of the high refractive index layer may be different from each other.

(Formation method)
As a method for forming the high refractive index layer, known methods that have been generally used can be used as appropriate, and examples thereof include a wet coating method. For example, by applying a coating liquid (high refractive index layer coating liquid) in which a material for forming a high refractive index layer (metal oxide fine particles, curable resin, additive, solvent, etc.) is dispersed or dissolved A high refractive index layer is formed.
Examples of the wet coating method include a roll coating method, a spin coating method, a dip coating method, a bar coating method, and a gravure coating method.

  Further, if necessary, the solvent (volatilizing resin, etc.) applied as described above is volatilized by drying the solvent or irradiated with heat or active energy rays (ultraviolet rays, electron beams, radiation, etc.). May be cured.

  In addition, as a material contained in a high refractive index layer, the active energy ray hardening resin hardened | cured by irradiation of active energy rays (an ultraviolet ray, an electron beam, radiation, etc.) among the said curable resin is preferable. By including the active energy ray curable resin, the production efficiency is improved, and the performance degradation of the piezoelectric body caused by the formation of the high refractive index layer can be further suppressed.

From the viewpoint of further improving the adhesion between the surface of the polymer piezoelectric film and the high refractive index layer and the coating property of the high refractive index layer on the surface of the polymer piezoelectric film, corona treatment, itro treatment, ozone treatment, plasma treatment. The surface of the polymer piezoelectric film can also be treated by, for example.
In addition, adhesion and coating properties can be improved by coating different surfaces on the surface of the polymer piezoelectric film. Examples of such materials include inorganic substances such as metals and metal oxides; organic substances such as resins; organic / inorganic composite compositions containing resins and metal oxide fine particles. As the resin, a cured product obtained by curing with temperature or active energy rays can also be used.

<Low refractive index layer>
〔material〕
The material for the low refractive index layer is not particularly limited as long as it can adjust the optical characteristics (for example, transmittance, color, bone appearance) of the laminate. Inorganic substances such as resins; organic substances such as resins; composite compositions containing resins and fine particles;
Examples of the metal include at least one selected from Al, Si, Ti, V, Cr, Fe, Co, Ni, Cu, Zn, In, Sn, W, Ag, Au, Pd, Pt, Sb, Ta, and Zr. Or an alloy thereof.
Examples of the metal oxide and metal oxide fine particles include titanium oxide, zirconium oxide, zinc oxide, niobium oxide, antimony oxide, tin oxide, indium oxide, cerium oxide, aluminum oxide, silicon oxide, magnesium oxide, yttrium oxide, and oxide. Examples thereof include ytterbium, tantalum oxide, and composite oxides thereof. These metal oxides and metal oxide fine particles may be used alone or in combination of two or more.
Examples of the inorganic substance include silicon oxide, aluminum oxide, magnesium oxide, magnesium fluoride, aluminum fluoride, calcium fluoride, cerium fluoride, or a mixture thereof. These inorganic substances may be used alone or in combination of two or more.
Examples of the fine particles include silicon oxide, aluminum oxide, magnesium oxide, magnesium fluoride, aluminum fluoride, calcium fluoride, cerium fluoride, or a mixture thereof. Examples of the hollow inorganic fine particles include fluorine resin fine particles; silicone resin fine particles; styrene resin fine particles; acrylic resin fine particles; glass; shirasu; silica; alumina; These fine particles may be used alone or in combination of two or more.
The average primary particle size of the fine particles is preferably from 1 nm to 500 nm, more preferably from 5 nm to 300 nm, and even more preferably from 10 nm to 200 nm, from the viewpoint of transparency. Scattering of visible light is suppressed when it is 500 nm or less, and secondary aggregation of fine particles is suppressed when it is 1 nm or more, which is desirable from the viewpoint of maintaining transparency.
Examples of the resin (organic substance) include the same materials as those used in the high refractive index layer, fluorine resins, and silicone resins. Moreover, the hardened | cured material obtained by making it harden | cure with temperature or an active energy ray can also be utilized.

[Refractive index]
The refractive index n2 of the low refractive index layer is preferably 1.30 to 1.60, more preferably 1.40 to 1.50, from the viewpoint of suppressing the decrease in transmittance and coloration.
Further, the refractive index n2 of the low refractive index layer is preferably smaller than the refractive index n1 of the high refractive index layer, that is, satisfies n2 <n1 from the viewpoint of suppressing a decrease in transmittance and coloration.

  As a means for setting the refractive index n2 of the low refractive index layer in the above range, when the low refractive index layer is made of a transparent metal oxide or a composite metal oxide, the material contained in the low refractive index layer (metal, metal Method for selecting ratio of oxide, resin, additive, etc .; Method for selecting film formation method (for example, vacuum deposition method, sputtering method, CVD method, ion plating method, spray method); Film formation condition (oxygen gas) For example, a method for selecting conditions (temperature, time, pressure, etc.) for annealing treatment, and the like. In addition, when the low refractive index layer is made of a cured product containing a curable resin, a method for selecting the curing conditions (temperature, time, etc.) of the curable resin; materials contained in the low refractive index layer (curable resin, fine particles) , Additives, etc.) ratios; and the like.

[Measurement method of refractive index]
The method for measuring the refractive index n2 of the low refractive index layer will be described in detail in Examples.

[Film thickness]
The film thickness d2 of the low refractive index layer is preferably 5 nm to 500 nm, more preferably 10 nm to 200 nm, and even more preferably 25 to 80 nm from the viewpoint of suppressing the decrease in transmittance and coloration.

  The film thickness d2 of the low refractive index layer is measured as follows. A laminate including the low refractive index layer is cut into a size of 1 mm × 10 mm and embedded in an epoxy resin for an electron microscope. This is fixed to an ultramicrotome sample holder, and a cross-sectional thin section parallel to the short side of the embedded sample piece is prepared. Next, in a section where the thin film of this section is not significantly damaged, a transmission electron microscope (manufactured by JEOL, JEM-2010) is used to obtain a photograph at an acceleration voltage of 200 kV and a bright field at an observation magnification of 10,000 times. The film thickness is obtained from the photograph taken.

  Note that a plurality of low refractive index layers may be provided. In this case, the film thickness d2 of the low refractive index layer is the total thickness of the low refractive index layer. When a plurality of low refractive index layers are provided, the refractive index n2 of the low refractive index layer may be different from each other.

(Formation method)
As a method for forming the low refractive index layer, known methods that have been generally used can be used as appropriate.
Specifically, when the low refractive index layer is made of a transparent metal oxide or a composite metal oxide, examples of the method for forming the low refractive index layer include a vacuum deposition method, a sputtering method, a CVD method, an ion plating method, a spraying method. Method, wet coating and the like. Among these, the sputtering method is preferable from the viewpoint of reducing variation in film thickness. For example, when a silicon oxide film is formed by a sputtering method, a single crystal, polycrystal, columnar silicon target, or the like is used as a target. However, in order to suppress target surface oxidation and moisture adsorption, the target is vacuum-reduced. It is preferable to use one that has been stored under an environment of N ₂ purge, low humidity, 5% RH or less, preferably 1% RH or less. More preferably, in order to suppress the adsorption of reactive gas or moisture to the non-erosion part, a hollow target or a silicon target with a glass coating on the non-erosion part may be used.

When the low refractive index layer is made of a composition containing a resin and, if necessary, an inorganic substance or resin fine particles, a method for forming the low refractive index layer includes, for example, a wet coating method. In this case, for example, a coating liquid (low refractive index layer coating liquid) in which a material for forming the low refractive index layer (inorganic matter, resin fine particles, resin, additive, solvent, etc.) is dispersed or dissolved is applied. Thus, a low refractive index layer is formed.
As the resin, a curable resin may be used, and if necessary, the solvent (e.g., curable resin) applied as described above is volatilized by drying, or heat or active energy rays (ultraviolet, The curable resin may be cured by irradiation with an electron beam or radiation.
The material contained in the low refractive index layer is preferably an active energy ray curable resin cured by irradiation with active energy rays (ultraviolet rays, electron beams, radiation, etc.) among the curable resins. By including the active energy ray-curable resin, the production efficiency can be improved, and the performance degradation of the piezoelectric body caused by the formation of the low refractive index layer can be further suppressed.

<Transparent conductive layer>
〔material〕
As a material for the transparent conductive layer, a metal film, a conductive metal oxide film, a conductive polymer film, a conductive composition such as a metal or a resin containing a conductive metal oxide, or the like can be used. Although not particularly limited, it is preferable to use, for example, indium-tin oxide, indium oxide, tin oxide, zinc oxide, indium-zinc oxide, or the like from the viewpoint of suppressing the decrease in transmittance and coloration. These oxides may be doped with a dopant such as a metal, and may be in a crystalline state or an amorphous state. Silver nanowires, carbon nanotubes, graphene, and resin compositions containing them can also be used.
The surface resistance of such a transparent conductive layer is preferably 2000 Ω / sq or less, more preferably 1000 Ω / sq, further preferably 500 Ω / sq, and particularly preferably 200 Ω / sq from the viewpoint of power consumption of the device.

[Refractive index]
The refractive index n3 of the transparent conductive layer is preferably 1.85 to 2.35 from the viewpoint of suppressing a decrease in transmittance and coloration.
Further, as described above, the refractive index n3 of the transparent conductive layer preferably satisfies the refractive index n1 of the high refractive index layer, that is, satisfies n1 ≦ n3.
Means for setting the refractive index n3 of the transparent conductive layer within the above range include: a method of selecting a material of the transparent conductive layer; a method of selecting formation conditions (temperature, time, pressure, etc.); and conditions of annealing treatment (temperature, A method of selecting time, pressure, etc.).

[Measurement method of refractive index]
A method for measuring the refractive index n3 of the transparent conductive layer will be described in detail in Examples.

[Film thickness]
The film thickness d3 of the transparent conductive layer is preferably 5 nm to 200 nm, more preferably 5 nm to 60 nm, from the viewpoint of suppressing the decrease in transmittance and coloration.
The film thickness d3 of the transparent conductive layer is measured by a method based on the method for measuring the film thickness d1 of the high refractive index layer.

(Formation method)
As a method for forming the transparent conductive layer, known methods that have been generally used can be appropriately used. For example, a vacuum deposition method, a sputtering method, an ion plating method, a CVD method, an electron beam deposition method, a sol- Examples thereof include a gel method and a wet coating method.

<First cured resin layer>
The laminate of the present invention has the viewpoint of improving the adhesion between the high refractive index layer and the polymer piezoelectric film, the viewpoint of preventing the polymer piezoelectric film from being scratched, the viewpoint of preventing the blocking of the polymer piezoelectric film, and the thermal contraction rate. From the viewpoint of lowering the cured resin layer (hereinafter referred to as “first cured resin”) between the polymeric piezoelectric film and the high refractive index layer and / or on the main surface of the polymeric piezoelectric film in which the high refractive index layer is not formed. It may be preferable to have a layer).

〔material〕
The material of the cured resin layer is not particularly limited, but for example, acrylic compounds, methacrylic compounds, vinyl compounds, allyl compounds, urethane compounds, epoxy compounds, epoxide compounds, glycidyl compounds, At least one selected from the group consisting of oxetane compounds, melamine compounds, cellulose compounds, ester compounds, silane compounds, silicone compounds, siloxane compounds, silica-acrylic hybrid compounds, and silica-epoxy hybrid compounds. It is preferable to include a material (curable resin).
Among these, acrylic compounds, epoxy compounds, and silane compounds are more preferable.
Moreover, in order for the cured resin layer to exhibit a necessary function, various additives may be included. The additive may be an inorganic filler or an organic substance such as a low molecule or a polymer. The average primary particle size of the inorganic filler is preferably from 1 nm to 500 nm, more preferably from 5 nm to 300 nm, and even more preferably from 10 nm to 200 nm from the viewpoint of transparency. Scattering of visible light is suppressed when it is 500 nm or less, and secondary aggregation of the inorganic filler is suppressed when it is 1 nm or more, which is desirable from the viewpoint of maintaining transparency.

[Refractive index]
The refractive index of the cured resin layer is preferably 1.45 to 1.55, more preferably 1.46 to 1.52, from the viewpoint of suppressing a decrease in transmittance.
As a means for setting the refractive index of the cured resin layer within the above range, a method of selecting a ratio of materials (curable resin, additives, etc.) contained in the cured resin layer; curing conditions of the curable resin (temperature, And the like.

[Measurement method of refractive index]
The method for measuring the refractive index of the cured resin layer will be described in detail in Examples.

[Film thickness]
Although the film thickness of a cured resin layer is not specifically limited, The range of 0.01 micrometer-10 micrometers is preferable.
When the thickness is 0.01 μm or more, for example, the cured resin layer exhibits functions such as a hard coat layer described later.
On the other hand, when the thickness is 10 μm or less, a large charge is generated in the electrode when the electrode (transparent conductive layer) is provided in the laminate.

  The upper limit value of the thickness is more preferably 6 μm or less, and further preferably 3 μm or less. Further, the lower limit value is more preferably 0.2 μm or more, and further preferably 0.3 μm or more.

However, in the case where the cured resin layer (first cured resin layer) is a multilayer film composed of a plurality of functional layers, the above thickness represents the thickness of the entire multilayer film. Further, the cured resin layer may be on both sides of the polymer piezoelectric film. Further, the refractive indexes of the cured resin layers may be different values.
In addition, the film thickness of the cured resin layer is determined by the following formula using a digital length measuring device DIGIMICRO STAND MS-11C manufactured by Nikon Corporation.
Formula d = dt-dp
dt: Average thickness of 10 positions of the laminate in which the cured resin layer is formed on the polymer piezoelectric film dt: Average thickness of 10 positions of the polymer piezoelectric film before forming the cured resin layer or after removing the cured resin layer

[Type of cured resin layer (use)]
Examples of the cured resin layer include various functional layers. As functional layers, for example, easy adhesion layer, hard coat layer, anti-reflection layer, anti-glare layer, easy slip layer, anti-block layer, protective layer, adhesive layer, adhesive layer, antistatic layer, heat dissipation layer, ultraviolet absorption layer, anti-layer Examples include a Newton ring layer, a light scattering layer, a polarizing layer, a gas barrier layer, and a hue adjustment layer. The functional layer may be a layer having two or more of these functions. Among these, at least one of an easy adhesion layer, a hard coat layer, an antistatic layer, and an antiblock layer is preferable from the viewpoint of suppressing a decrease in transmittance and coloration.
When the first cured resin layers are provided on both main surfaces of the polymer piezoelectric film, the two first cured resin layers may be the same functional layer or different functional layers.

  Further, by forming the cured resin layer, defects such as die lines and dents on the surface of the polymer piezoelectric film are filled, and the appearance is improved. In this case, the smaller the refractive index difference between the polymer piezoelectric film and the cured resin layer, the more the reflection at the interface between the polymer piezoelectric film and the cured resin layer is reduced, and the appearance is further improved.

(Formation method)
As a method of forming the cured resin layer, a known method that has been generally used can be appropriately used. For example, a wet coating method can be used. For example, the cured resin layer is formed by applying a coating liquid in which a material (curable resin, additive, solvent, or the like) for forming the cured resin layer is dispersed or dissolved.

  Further, if necessary, the solvent (volatilizing resin, etc.) applied as described above is volatilized by drying the solvent or irradiated with heat or active energy rays (ultraviolet rays, electron beams, radiation, etc.). Is cured.

  In addition, as a material contained in a cured resin layer, the active energy ray cured resin hardened | cured by irradiation of active energy rays (an ultraviolet ray, an electron beam, radiation, etc.) among the said curable resin is preferable. By including the active energy ray curable resin, the production efficiency is improved, and the performance degradation of the polymer piezoelectric film caused by the formation of the cured resin layer can be further suppressed.

  Moreover, it is preferable that the said cured resin layer contains the three-dimensional crosslinked resin which has a three-dimensional crosslinked structure from a viewpoint of raising a crosslinking density.

  As a means for producing a cured product having a three-dimensional crosslinked structure, a method using a monomer having three or more polymerizable functional groups (a monomer having three or more functional groups) as a curable resin, or a crosslinking having three or more polymerizable functional groups. Examples include a method using a crosslinking agent (a trifunctional or higher functional crosslinking agent), and a method using a crosslinking agent such as an organic peroxide as a crosslinking agent. A plurality of these means may be used in combination.

  Examples of the tri- or higher functional monomer include (meth) acrylic compounds having three or more (meth) acrylic groups in one molecule, and epoxy compounds having three or more epoxy groups in one molecule. .

In the present specification, “(meth) acrylic group” represents at least one of an acrylic group and a methacrylic group.
Further, “having three or more (meth) acrylic groups in one molecule” means having at least one of an acrylic group and a methacrylic group in one molecule, and an acrylic group and a methacrylic group in one molecule. The total number is 3 or more.

Here, as a method for confirming whether or not the material contained in the cured resin layer is a cured product having a three-dimensional cross-linked structure, a method of measuring the gel fraction can be mentioned.
Specifically, the gel fraction can be derived from the insoluble matter after the cured resin layer is immersed in a solvent for 24 hours. In particular, it can be presumed that a solvent having a gel fraction of a certain level or more has a three-dimensional crosslinked structure, whether the solvent is a hydrophilic solvent such as water or a new oily solvent such as toluene.

The use of the cured resin layer by the wet coat method can be applied to any of the above-listed layers. In the case of the wet coating method, the polymer piezoelectric film may be stretched after the coating liquid has been applied to the original film before stretching of the polymer piezoelectric film, or the coating liquid may be applied after stretching the polymer piezoelectric film original film.
The thickness (one layer) of the cured resin layer by wet coating is preferably in the range of several tens of nm to 10 μm.
Moreover, various organic substances and inorganic substances such as a refractive index adjusting agent, an ultraviolet absorber, a leveling agent, an antistatic agent, and an antiblocking agent can be added to the cured resin layer according to the purpose.
From the viewpoint of improving the adhesion between the surface of the polymer piezoelectric film and the cured resin layer and the coating property on the surface of the polymer piezoelectric film, the polymer piezoelectric film can be treated by corona treatment, itro treatment, ozone treatment, plasma treatment, etc. The surface can also be treated.

[Relative permittivity]
The relative dielectric constant of the cured resin layer is preferably 1.5 or more, more preferably 2.0 or more and 20000 or less, and further preferably 2.5 or more and 10,000 or less.
Due to the relative dielectric constant being in the above range, when an electrode (transparent conductive layer) is further provided on the cured resin layer in the laminate via a high refractive index layer and a low refractive index layer, a large charge is generated by the electrode. .

The relative dielectric constant of the cured resin layer is measured by the following method.
After forming a cured resin layer on one side of the polymer piezoelectric film, Al of about 50 nm is deposited on both sides of the laminate of the polymer piezoelectric film and the cured resin layer using Showa Vacuum SIP-600. A 50 mm × 50 mm film is cut out from this laminate. This test piece is connected to LCR METER 4284A manufactured by HEWLETT PACKARD, the capacitance C is measured, and the relative dielectric constant εc of the cured resin layer is calculated by the following equation.
εc = (C × d × 2.7) / (ε ₀ × 2.7 × S−C × dp)
d: thickness of cured resin layer, ε ₀ : vacuum dielectric constant, S: test piece area, dp: thickness of polymer piezoelectric film

[Internal haze of cured resin layer]
The internal haze of the cured resin layer is preferably 10% or less, more preferably 0.0% or more and 5% or less, and further preferably 0.01% or more and 2% or less.
When the internal haze is in the above range, excellent transparency is exhibited, and it can be effectively used as a touch panel, for example.

The internal haze Hc of the cured resin layer is calculated by the following formula.
Hc = H-Hp
H: Internal haze of laminated body of polymer piezoelectric film and cured resin layer Hp: Internal haze of polymer piezoelectric film before formation of cured resin layer or after removal of cured resin layer The measuring method is as described above. The internal haze of the laminate is also measured by the same method as the internal haze of the polymer piezoelectric film.

≪Laminated body≫
In addition, the laminate of the present invention has a polymer piezoelectric film, a high refractive index layer, a low refractive index layer, and a transparent conductive layer in this order. On the opposite side, the adhesive layer and the peelable release film may be provided in this order. The laminated body may have a first cured resin layer between the polymer piezoelectric film and the high refractive index layer.

<Adhesive layer>
〔material〕
The adhesive layer is a layer having adhesiveness. As the adhesive layer, an adhesive layer of a double-sided tape (OCA; Optical Clear Adhesive) in which both surfaces are laminated with a separator can be used.
The pressure-sensitive adhesive layer can also be formed using a solvent-based, solvent-free, water-based or other pressure-sensitive adhesive coating solution, UV curable OCR (Optical Clear Resin), hot melt adhesive, or the like.

  As OCA, optical transparent adhesive sheet LUCIACS series (manufactured by Nitto Denko Corporation), highly transparent double-sided tape 5400A series (manufactured by Sekisui Chemical Co., Ltd.), optical adhesive sheet Optia series (manufactured by Lintec Corporation), high transparency adhesive Agent transfer tape series (manufactured by Sumitomo 3M Co., Ltd.), SANCUARY series (manufactured by Sanei Kaken Co., Ltd.), etc.

  Adhesive coating solutions include SK Dyne Series (manufactured by Soken Chemical Co., Ltd.), Fine Tack Series (manufactured by DIC Corporation), Bon Coat Series, LKG Series (manufactured by Fujikura Kasei Co., Ltd.), and Coponille Series (Nippon Gosei Chemical Co., Ltd. Company-made).

  As the adhesive layer, from the viewpoint of preventing the heating of the polymer piezoelectric film, an OCA adhesive layer, an adhesive layer formed using OCR, an adhesive layer formed by applying an adhesive coating solution to a member other than the polymer piezoelectric film An adhesive layer formed using a hot melt adhesive on a member other than the polymer piezoelectric film is preferred.

Although it does not specifically limit as a material of an adhesion layer, It is preferable that resin is included.
Examples of the resin include acrylic resin, methacrylic resin, urethane resin, cellulose resin, vinyl acetate resin, ethylene-vinyl acetate resin, epoxy resin, nylon-epoxy resin, vinyl chloride resin, chloroprene rubber resin, and cyanoacrylate resin. Resin, silicone resin, modified silicone resin, aqueous polymer-isocyanate resin, styrene-butadiene rubber resin, nitrile rubber resin, acetal resin, phenol resin, polyamide resin, polyimide resin, melamine resin, urea resin, bromine Resins, starch resins, polyester resins, polyolefin resins and the like can be mentioned.

[Film thickness]
The thickness of the pressure-sensitive adhesive layer is not particularly limited, but from the viewpoint of maintaining the adhesion of the pressure-sensitive adhesive layer and suppressing the decrease in transmittance, the thickness is 5 μm or more, preferably 7 to 100 μm, more preferably 7 to The range of 60 μm, more preferably 10 to 30 μm is preferable.
The film thickness d of the adhesive layer is determined by the following formula using a digital length measuring device DIGIMICRO STAND MS-11C manufactured by Nikon Corporation.
Formula d = dt-dp
dt: Average thickness of 10 laminates having an adhesive layer dt: Average thickness of 10 laminates before formation of the adhesive layer or after removal of the adhesive layer

[Acid value of adhesive layer]
The acid value of the pressure-sensitive adhesive layer is preferably 0.01 mgKOH / g to 10 mgKOH / g, more preferably 0.05 mgKOH / g to 5 mgKOH / g, from the viewpoint of suppressing adhesion strength and deterioration of the laminate under a moist heat environment. 0.1 mgKOH / g to 1 mgKOH / g is more preferable. By maintaining the acid value of the adhesive layer at 0.01 mg KOH / g to 10 mg KOH / g, the layer having the acid value with the polymer piezoelectric film while maintaining the stability of the polymer piezoelectric film (particularly heat and moisture resistance) It is possible to increase the adhesion with.
In the laminate of the present invention, the acid value of the adhesive layer refers to the amount (mg) of KOH required to neutralize the free acid in 1 g of the adhesive layer. The amount (mg) of KOH is measured by titrating an adhesive layer dissolved or swollen in a solvent with a 0.005 M KOH (potassium hydroxide) ethanol solution using phenolphthalein as an indicator.

<Releasable release film>
〔material〕
As a peelable release film material, a material having releasability (peelability) is preferably used. The release film may be a single film or a multilayer film composed of a plurality of layers. When the release film is a multilayer film composed of a plurality of layers, the release film is preferably formed in a structure in which a material having releasability is provided on the surface facing the adhesive layer. In this case, the release film may be formed in a structure including a base material and a material having releasability.

Specific examples of the releasable material include polyester resins such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate; olefin resins such as polyethylene, polypropylene, and polymethylpentene; polytetrafluoroethylene, polyfluorinated Fluorine resins such as vinylidene, polyvinyl chloride, styrene (meth) acrylic acid copolymers, styrene (meth) acrylic acid ester copolymers, vinyl resins such as polystyrene and ethylene vinyl acetate; and the like.
In addition, polyurethane resin, polyimide resin, polyamide resin, silicone resin, acrylic silicone resin, melamine resin, alkyd resin, wax resin, and the like can be given.
The release film may be a single film of these or a multilayer film composed of a plurality of layers. In this case, the release film is preferably formed in a structure in which a material having releasability is provided on a surface facing the adhesive layer. Among these, a silicone resin, a fluororesin, a polyester resin, a polyolefin resin, an alkyd resin, and a wax resin are used as the material having releasability provided on the surface facing the adhesive layer in order to further improve the peelability from the adhesive layer. It is more preferable to use a silicone resin.

  Examples of silicone resins include those obtained by reacting silanol-functional dimethylpolysiloxane with methylhydrogenpolysiloxane or methylmethoxysiloxane in the presence of an organotin catalyst (thermal condensation reaction type); Or a reaction of methyl vinyl polysiloxane having vinyl groups at both ends and side chains with methyl hydrogen polysiloxane in the presence of a platinum-based catalyst (thermal addition reaction type); siloxane containing alkenyl group and mercapto group With photopolymerization agent added (ultraviolet curing type (radical addition type)); using the same platinum catalyst as thermal addition reaction type (ultraviolet curing type (hydrosilyl type)); containing (meth) acrylic group Siloxane and photopolymerization agent (UV curable type (radical polymerization type)); Siloxy containing epoxy group Onium salt photoinitiator (ultraviolet curable type (cationic polymerization type)); radical polymerizable group-containing siloxane (electron beam curable type, but no functional group, no photoinitiator) May also be included). Moreover, the form of the silicone resin can be appropriately selected from a solvent type, an emulsion type, a solventless type, and the like.

〔Base material〕
When the release film is formed in a structure including a substrate and a material having releasability, as the substrate, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polyethylene, polypropylene, polymethylpentene, triacetyl Examples of the resin include cellulose, cellophane, rayon, polystyrene, polycarbonate, polyimide, polyamide, polyphenylene sulfide, polyetherimide, polyethersulfone, aromatic polyamide, and polysulfone. These uniaxially or biaxially stretched films; nonwoven fabrics; foams Examples include the body. The substrate can be selected from glass, metal foil, ceramic, paper and the like.

[Other materials]
If necessary, the release film may be provided with a layer containing other materials such as an antistatic agent, an oligomer migration inhibitor, a smoothing agent, and an easy-adhesive layer on a layer other than the surface facing the adhesive layer. Good. For example, when the release film is formed in a structure including a base material and a material having releasability, the surface where the base material and the material having releasability face each other, and the releasability of the base material A layer containing the above-described other material can be provided on either or both of the surface opposite to the surface facing the material having the above.

[Film thickness]
The film thickness of the release film is not particularly limited, but from the viewpoint of ease of release and handling, a range of 5 μm or more is preferable, a range of 10 μm to 100 μm is more preferable, and a range of 20 μm to 80 μm. Is more preferable, and the range of 30 μm to 80 μm is particularly preferable.

[Peelability of release film (release property)]
In order to make the release film peelable, the adhesive force between the adhesive layer and the polymer piezoelectric film is preferably larger than the adhesive force between the adhesive layer and the release film.

(Formation method)
As a method for forming the release film, a known method that has been generally used can be appropriately used. For example, the release film may be formed by extruding a resin for forming the release film with a film forming machine. When the release film is a multilayer film composed of a plurality of layers, each of the formed release films may be formed into a multilayer with an adhesive, and co-extruded to form a multilayer by a multilayer film forming machine. It may be formed.
Further, when the release film is a multilayer film composed of a plurality of layers formed in a structure including a base material and a material having releasability, the formed base material and the formed material having releasability May be formed in multiple layers with an adhesive, or may be formed into multiple layers by extrusion-forming a material having releasability on the formed base material, or the material constituting the base material and the mold release The material having the property may be co-extruded with a multilayer film forming machine to form a multilayer.

  Further, it may be formed by a wet coating method. For example, when a release film is formed by a wet coating method, a coating liquid (release film coating liquid) in which a material (resin, additive, etc.) for forming the release film is dispersed or dissolved is used as an adhesive layer. It can be formed by coating on top. In addition, when the release film is a multilayer film composed of a plurality of layers formed in a structure including a substrate and a material having releasability, it is formed by applying a release film coating solution onto the substrate. Can be made.

When a material having releasability is formed by a wet coating method, the material having releasability is used as a coating solution such as a solution or an emulsion liquid, and this is used as a roll coater, comma coater, die coater, Mayer bar coater, reverse roll. You may form by apply | coating and drying on an adhesion layer or a base material by well-known methods, such as a coater and a gravure coater.
When the release film is a multilayer film composed of a plurality of layers, the surface opposite to the surface facing the adhesive layer of the release film, or the surface opposite to the surface facing the adhesive layer of the release film. A surface activation treatment such as a corona discharge treatment, a flame treatment, an ozone treatment, or an anchor coating treatment using an anchor treatment agent may be applied to a substrate in contact with the surface. Since the adhesion of the multilayer film is improved by such treatment, it can be improved from the releasability with the adhesive layer.

<Second cured resin layer>
The laminate of the present invention may have a cured resin layer (hereinafter also referred to as “second cured resin layer”) between the polymer piezoelectric film and the adhesive layer.
The characteristics (material, type (use), refractive index, film thickness, etc.) of the second cured resin layer may be the same as or different from those of the first cured resin layer. The second cured resin layer can be formed by the same method as the first cured resin layer.

≪Laminated body≫
In addition, the laminate of the present invention has a polymer piezoelectric film, a high refractive index layer, a low refractive index layer, and a transparent conductive layer in this order. You may have a peelable protective film on the opposite side. The laminated body may have a first cured resin layer between the polymer piezoelectric film and the high refractive index layer.

<Peelable protective film>
As for a protective film, the film which has a base material and the adhesion layer laminated | stacked on one main surface of a base material is mentioned, for example. In addition, a protective film is good also as a single layer structure of a base material. In this case, the protective film is disposed on the surface of the polymer piezoelectric film or a third cured resin layer described later, for example, electrostatically or due to the adhesiveness of the protective film itself.
〔material〕
Examples of the base material include polyethylene resin, polypropylene resin, polyethylene / polypropylene copolymer resin, cyclic polyolefin, polyester resin, nylon resin, polyvinyl alcohol resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl chloride resin, and polycarbonate resin. , Polymethyl methacrylate resin, polyurethane resin, fluororesin, polyacrylonitrile, polybutene resin, polyimide resin, polyarylate resin, acetylcellulose resin and the like.
The base material may be a multilayer body of these resin layers.

  Examples of the material for the adhesive layer include ethylene-vinyl acetate copolymer (EVA) adhesives, acrylic adhesives, rubber adhesives, polyolefin adhesives (eg, polyethylene oligomer adhesives), and cellulose adhesives. (For example, glue), silicone adhesive, urethane adhesive, vinyl alkyl ether adhesive, polyvinyl alcohol adhesive, polyvinyl pyrrolidone adhesive, polyacrylamide adhesive, and the like. Among these, as the material for the adhesive layer, EVA adhesives, acrylic adhesives, and rubber adhesives are preferable from the viewpoint of moisture resistance and adhesiveness, and EVA adhesives are more preferable.

Here, examples of the adhesive polymer of the acrylic adhesive include, for example, an alkyl group having 1 to 10 carbon atoms such as 2-ethylhexyl acrylate, butyl acrylate, isooctyl acrylate, butyl methacrylate, propyl methacrylate, and the like ( A copolymer of a monomer mixture containing a (meth) acrylic acid ester and a functional group-containing unsaturated monomer such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, hydroxyethyl acrylate, and hydroxyethyl methacrylate. Preferably mentioned.
Preferable examples of the adhesive polymer of the rubber adhesive include styrene / butadiene random copolymer, styrene / isoprene block copolymer, and natural rubber.

〔Characteristic〕
The adhesive strength of the protective film (the adhesive strength of the protective film to the object (polymer piezoelectric film or third cured resin layer described later) to which the protective film is bonded) is preferably 0.01 N / 50 mm to 1.5 N / 50 mm. 0.02 N / 50 mm to 1.0 N / 50 mm is more preferable. When the adhesive strength of the protective film is within the above range, peeling of the protective film from the laminate is suppressed, and easy peeling of the protective film is easily realized when peeling the protective film.
The adhesive strength of the protective film is a value measured by pulling the protective film from the laminate having the protective film in a 180 ° direction at a speed of 300 mm / min with a tensile tester.

[Film thickness]
The thickness of the protective film is not particularly limited, but from the viewpoint of enhancing the protective function, the thickness is preferably 5 μm or more, more preferably 10 μm to 100 μm, even more preferably 20 μm to 80 μm, and even more preferably 30 μm to 30 μm. A range of 50 μm is particularly preferred.
Here, the film thickness of the substrate is preferably in the range of 9 μm to 99 μm, more preferably in the range of 19 μm to 79 μm, and still more preferably in the range of 29 μm to 49 μm. On the other hand, the thickness of the adhesive layer is preferably in the range of 1 μm to 20 μm, and more preferably in the range of 3 μm to 10 μm.

(Formation method)
As a method of forming the protective film, a known method that has been generally used can be appropriately used. For example, the protective film is formed by extruding a resin for forming the protective film with a film forming machine. Further, it may be formed by a wet coating method. When forming a protective film by the wet coat method, a coating liquid (coating liquid for protective film) in which a material (resin, additive, etc.) for forming the protective film is dispersed or dissolved is applied onto the polymer piezoelectric film. It is formed by coating.
Specifically, the material to be the base material and the material to be the adhesive layer are formed by extrusion using a multilayer film forming machine to form a protective film.
In addition, from the viewpoint of improving the releasability (peelability) of the protective film, the surface of the protective film can be treated by corona treatment, itro treatment, ozone treatment, plasma treatment, or the like.

  Examples of commercially available protective films include the PAC series from Sanei Kaken Co., Ltd., the 622 series from Sekisui Chemical Co., Ltd., the FM series from Daio Paper Industries Co., Ltd., and the V series from Sumilon Corporation.

<Third cured resin layer>
The laminate of the present invention may further have a cured resin layer (hereinafter also referred to as “third cured resin layer”) between the polymer piezoelectric film and the peelable protective film.
The characteristics (material, type (use), refractive index, film thickness, etc.) of the third cured resin layer may be the same as or different from those of the first cured resin layer. The third cured resin layer can be formed by the same method as the first cured resin layer.

[First embodiment]
FIG. 1A shows a cross-sectional view of the first embodiment of the laminate of the present invention. The laminate 100 of the first aspect includes a polymer piezoelectric film 10, a high refractive index layer 11, a low refractive index layer 12, and an electrode pattern 14 as a transparent conductive layer in this order. Further, a first cured resin layer (not shown) may be provided between the polymer piezoelectric film 10 and the high refractive index layer 11.
The laminated body of the first aspect has the above-described configuration, so that a decrease in transmittance due to the provision of the transparent conductive layer is suppressed, and coloration due to the provision of the transparent conductive layer is suppressed.

[Second embodiment]
FIG. 1B shows a cross-sectional view of the second embodiment of the laminate of the present invention. The laminate 101 of the second embodiment has a polymer piezoelectric film 10, a high refractive index layer 11A, a low refractive index layer 12A, and an electrode pattern 14A as a transparent conductive layer in this order. The high refractive index layer 11B, the low refractive index layer 12B, and the electrode pattern 14B as a transparent conductive layer are provided in this order on the opposite side of the film 10 from the high refractive index layer 11A. Further, a first cured resin layer (not shown) may be provided between the polymer piezoelectric film 10 and the high refractive index layer 11A and / or between the polymer piezoelectric film 10 and the high refractive index layer 11B. Good.
The laminated body of the second aspect has the above-described configuration, so that a decrease in transmittance due to the provision of the transparent conductive layer is suppressed, and coloration due to the provision of the transparent conductive layer is suppressed.

[Third embodiment]
In FIG. 2, sectional drawing of the 3rd aspect of the laminated body of this invention is shown. The laminated body 102 of the third aspect further includes an adhesive layer 16 and a release mold that can be peeled from the laminated body 100 of the first aspect on the side opposite to the high refractive index layer 11 when viewed from the polymer piezoelectric film 10. And a film 18 in this order. In addition, a first cured resin layer (not shown) may be provided between the polymer piezoelectric film 10 and the high refractive index layer 11, and a second between the polymer piezoelectric film 10 and the adhesive layer 16. May have a cured resin layer (not shown).
The laminated body of the 3rd aspect has the said structure, the fall of the transmittance | permeability by providing a transparent conductive layer is suppressed, and the coloration by providing a transparent conductive layer is suppressed.

[Fourth Embodiment]
In FIG. 3, sectional drawing of the 4th aspect of the laminated body of this invention is shown. The laminate 104 of the fourth aspect further has a peelable protective film 20 on the side opposite to the high refractive index layer 11 when viewed from the polymer piezoelectric film 10 with respect to the laminate 100 of the first aspect. Further, a first cured resin layer (not shown) may be provided between the polymer piezoelectric film 10 and the high refractive index layer 11, and between the polymer piezoelectric film 10 and the peelable protective film 20. May have a third cured resin layer (not shown).
The laminated body of the 4th aspect has the said structure, the fall of the transmittance | permeability by providing a transparent conductive layer is suppressed, and the coloration by providing a transparent conductive layer is suppressed.

<Physical properties of the laminate>
[Thermal dimensional stability (thermal shrinkage)]
In the laminate of the present invention, the thermal shrinkage rate when heated at 150 ° C. for 30 minutes is preferably 2.0% or less in both the MD direction and the TD direction.
In the laminated body, the whole or a part of the laminated body is heated in a step of crystallizing the formed transparent conductive layer or a step of connecting the transparent conductive layer and an external circuit when using the laminated body as a device. However, if the thermal contraction rate is large, the formed transparent electrode layer may be damaged or misaligned, the connection with the extraction electrode may be poor, or the laminate may be deformed. Is preferred.
The thermal dimensional stability of the laminate is evaluated by measuring the thermal shrinkage rate at 30 ° C. for 30 minutes in the MD direction and the TD direction, respectively. Specifically, the thermal contraction rate of the laminate is calculated by the following method.

  The heat shrinkage rate of the laminate was determined by placing a sample piece cut into a 100 mm square in the MD direction and a 100 mm square in the TD direction in an oven at 150 ° C. for 30 minutes, and removing the sample piece from the oven at room temperature. Measure dimensions in direction and TD direction. Using the measured value, the heat shrinkage rate is calculated from the following formula.

  Heat shrinkage rate = 100 × (size of sample piece before standing in oven−size of sample piece measured at room temperature after standing in oven) / size of sample piece before standing in oven

<Use of laminate>
The laminate of the present invention includes a speaker, a headphone, a touch panel, a remote controller, a microphone, an underwater microphone, an ultrasonic transducer, an ultrasonic applied measuring instrument, a piezoelectric vibrator, a mechanical filter, a piezoelectric transformer, a delay device, a sensor, an acceleration sensor, Shock sensor, vibration sensor, pressure sensor, tactile sensor, electric field sensor, sound pressure sensor, display, fan, pump, variable focus mirror, sound insulation material, sound insulation material, keyboard, sound equipment, information processing machine, measurement equipment, medical equipment It can be used in various fields such as.
Moreover, the laminated body of this invention can also be used as a touchscreen combined with the display apparatus. As the display device, for example, a liquid crystal panel, an organic EL panel, or the like can be used.
Moreover, the laminated body of this invention can also be used in combination with the touch panel (position detection member) of another system as a pressure sensor. Examples of the detection method of the position detection member include an anti-film method, a capacitance method, a surface acoustic wave method, an infrared method, and an optical method.

Moreover, a laminated body can be repeatedly stacked and used as a laminated piezoelectric element. As an example, a laminate is repeatedly stacked, and finally the surface of the laminate that is not covered with an electrode (transparent conductive layer) is covered with an electrode.
Further, when the laminated piezoelectric element includes polymer piezoelectric films in a plurality of laminated bodies, if the optical activity of the helical chiral polymer (A) contained in the polymer piezoelectric film of a certain layer is L, the other layers The helical chiral polymer (A) contained in the polymer piezoelectric film may be L-form or D-form. The arrangement of the polymer piezoelectric film can be appropriately adjusted according to the use of the piezoelectric element.

  For example, the first layer of the polymer piezoelectric film containing the L-form helical chiral polymer (A) as the main component contains the second high-density polymer containing the L-form helical chiral polymer (A) as the main component via the electrode. When laminated with a molecular piezoelectric film, the uniaxial stretching direction (main stretching direction) of the first polymer piezoelectric film intersects, preferably orthogonal, with the uniaxial stretching direction (main stretching direction) of the second polymer piezoelectric film. This is preferable because the direction of displacement of the first polymer piezoelectric film and the second polymer piezoelectric film can be made uniform, and the piezoelectricity of the entire laminated piezoelectric element is enhanced.

  On the other hand, the first layer of the piezoelectric polymer film containing the L-form helical chiral polymer (A) as the main component contains the second high-density polymer containing the D-form helical chiral polymer (A) as the main component via the electrode. When laminated with a molecular piezoelectric film, the uniaxial stretching direction (main stretching direction) of the first polymeric piezoelectric film is substantially parallel to the uniaxial stretching direction (main stretching direction) of the second polymeric piezoelectric film. It is preferable that the first polymer piezoelectric film and the second polymer piezoelectric film can be arranged in the same direction, and the piezoelectricity of the entire laminated piezoelectric element is enhanced.

  In particular, the electrode (transparent conductive layer) preferably has transparency. Here, the transparency of the electrode specifically means that the internal haze is 20% or less and the total light transmittance is 80% or more.

  The piezoelectric element using the laminate of the present invention can be applied to the above-described various piezoelectric devices such as speakers and touch panels. In particular, a piezoelectric element provided with a transparent electrode is suitable for application to a speaker, a touch panel, an actuator, and the like.

<Method for producing laminate>
As an example of a method for producing a laminate, a method for producing a laminate having a polymer piezoelectric film, a high refractive index layer, a low refractive index layer, and a transparent conductive layer in this order will be described.
First, a polymer piezoelectric film is manufactured. Examples of a method for producing a polymer piezoelectric film include a method of crystallizing and stretching (any of which may be first) on an amorphous sheet containing the optically active polymer described above. .

  The non-crystalline sheet is an optically active polymer (helical chiral polymer (A)) alone or a mixture containing the optically active polymer heated to a temperature equal to or higher than the melting point Tm of the optically active polymer, The sheet obtained by rapid cooling is shown. An example of the rapid cooling temperature is 50 ° C.

In the method for producing a polymer piezoelectric film, the optically active polymer (polylactic acid polymer or the like) may be used alone as a raw material for the polymer piezoelectric film (or amorphous sheet). Using a mixture of two or more optically active polymers (such as polylactic acid-based polymers) described above, or a mixture of at least one optically active polymer described above and at least one other component Also good.
The above mixture is preferably a mixture obtained by melt kneading.
Specifically, for example, when mixing an optically active polymer, or when mixing other components (for example, the above-described inorganic filler and crystal nucleating agent) with one or more types of optically active polymer, the optical activity to be mixed The polymer (along with other components as required) is used for 5 to 20 minutes under the conditions of mixer rotation speed 30 rpm to 70 rpm, 180 ° C. to 250 ° C. using a melt kneader (manufactured by Toyo Seiki Co., Ltd., Laboplast mixer). By melt-kneading, a blend of a plurality of types of optically active polymers or a blend of optically active polymers and other components such as inorganic fillers can be obtained.

  The polymer piezoelectric film is also manufactured by a manufacturing method including a step of stretching a sheet containing an optically active polymer (preferably an amorphous sheet) mainly in a uniaxial direction and an annealing treatment step in this order. it can.

In addition, the polymer piezoelectric film is a polymer piezoelectric film from the viewpoint of further improving the adhesion between the polymer piezoelectric film and the high refractive index layer and further improving the moisture heat resistance and tear strength of the polymer piezoelectric film. You may adjust the ratio of the acryl terminal of the polymer contained in.
Specifically, the polymer piezoelectric film was obtained by measuring a ¹ H-NMR spectrum of a solution obtained by dissolving 20 mg of the polymer piezoelectric film in 0.6 mL of deuterated chloroform, and measuring the measured ¹ H-NMR spectrum. Based on the following formula (X), when the ratio of the acrylic terminal of the polymer contained in the polymer piezoelectric film is determined, the ratio of the acrylic terminal of the polymer is 2.0 × 10 ⁻⁵ to 10 −10. It may be 0.0 × 10 ⁻⁵ .
Ratio of acrylic end of the polymer = integral value of peak derived from acrylic end of polymer / integral value of peak derived from methine in the main chain of the polymer Formula (X)
The polymeric piezoelectric film may contain at least one colorant in order to adjust the hue. Examples of the colorant include a bluing agent for correcting yellowishness.

  Next, a high refractive index layer is formed on the polymer piezoelectric film. The high refractive index layer is, for example, a step of applying a coating liquid (high refractive index layer coating liquid) in which a material containing metal oxide fine particles and a curable resin is dispersed or dissolved to a polymer piezoelectric film; The coating liquid can be formed through a process of drying the coating liquid as needed and a process of curing the coating liquid by irradiation with heat or active energy rays (ultraviolet rays, electron beams, radiation, etc.).

Next, a low refractive index layer is formed on the high refractive index layer. The low refractive index layer can be formed by a known method (vacuum deposition method, sputtering method, CVD method, ion plating method, spray method, wet coating method, etc.). For example, when SiO ₂ is formed as a low refractive index layer by sputtering, it is formed by using silicon as a target and adjusting film forming conditions (flow rate of oxygen gas, pressure, voltage, temperature, time, etc.). Can do. The low refractive index layer may be formed by a wet coating method.

Next, a transparent conductive layer is formed on the low refractive index layer.
The transparent conductive layer is formed on the low refractive index layer by a known method (vacuum evaporation method, sputtering method, ion plating method, CVD method, electron beam evaporation method, sol-gel method, wet coating method, etc.). After the formation, a part of the transparent conductive layer can be formed by etching with an acid or alkali using pattern forming means (masking, lithography, etc.). Alternatively, the low refractive index layer can be formed by masking a part of the low refractive index layer with a pattern mask, a mending tape or the like, and forming a transparent conductive layer on a part of the low refractive index layer by a known method. Moreover, even if the composition containing the material of the transparent conductive layer is partially applied to the low refractive index layer by a part coat method, a screen printing method, a gravure printing method, or the like, it can be formed.

  When the laminate has an adhesive layer and a peelable release film in this order on the side opposite to the high refractive index layer when viewed from the polymer piezoelectric film, or the high refractive index layer when viewed from the polymer piezoelectric film. When it has a peelable protective film on the opposite side, the adhesive layer, the peelable release film and the peelable protective film can be formed by the above-described methods. The same applies to the first to third cured resin layers.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist thereof.

<Production of polymer piezoelectric film>
As helical chiral polymer (A), NatureWorks LLC Corp. polylactic acid polymer (product ^name: Ingeo TM Biopolymer, brand: 4032D, weight average molecular weight Mw: 20 million in the melting point (Tm): 166 ° C., a glass transition temperature ( Tg): 57 ° C. to 60 ° C.) was prepared as a raw material.
The prepared raw material is put into an extrusion molding machine hopper, extruded from a T-die while being heated to 220 ° C. to 230 ° C., and brought into contact with a 55 ° C. cast roll for 0.5 minutes to produce a 150 μm thick pre-crystallized sheet. Filmed (pre-crystallization step). The crystallinity of the pre-crystallized sheet was measured and found to be 5.63%.
The obtained pre-crystallized sheet was stretched by roll-to-roll while being heated to 70 ° C. at a stretching speed of 1650 mm / min, and uniaxially stretched in the MD direction up to 3.3 times (stretching step). The thickness of the obtained film was 0.05 mm (50 μm).
Thereafter, the uniaxially stretched film was brought into contact with a roll heated to 130 ° C. for 60 seconds by roll-to-roll and annealed to produce a polymer piezoelectric film (annealing step).

<Measurement of physical properties of helical chiral polymer (A)>
The optical purity of the helical chiral polymer (A) was measured by the following method. Moreover, the weight average molecular weight and molecular weight distribution were measured by the above-mentioned method. The results are shown in Table 1.

[Optical purity]
The optical purity of the helical chiral polymer (A) (polylactic acid) contained in the polymer piezoelectric film was measured as follows.

First, 1.0 g sample (the above-mentioned polymer piezoelectric film) is weighed into a 50 mL Erlenmeyer flask, and 2.5 mL of IPA (isopropyl alcohol) and 5 mL of 5.0 mol / L sodium hydroxide solution are added to the sample. It was set as the solution.
Next, the Erlenmeyer flask containing the sample solution was placed in a water bath at a temperature of 40 ° C. and stirred for about 5 hours until the polylactic acid was completely hydrolyzed.
The sample solution after stirring for about 5 hours was cooled to room temperature, neutralized by adding 20 mL of 1.0 mol / L hydrochloric acid solution, and the Erlenmeyer flask was sealed and mixed well.
Next, 1.0 mL of the sample solution stirred above was placed in a 25 mL volumetric flask, and a mobile phase having the following composition was added thereto to obtain 25 mL of HPLC sample solution 1.
5 μL of the obtained HPLC sample solution 1 was injected into the HPLC apparatus, and HPLC measurement was performed under the following HPLC measurement conditions. From the obtained measurement results, the area of the peak derived from the D-form of polylactic acid and the area of the peak derived from the L-form of polylactic acid were determined, and the amount of L-form and the amount of D-form were calculated. Based on the obtained results, the optical purity (% ee) was determined.
As a result, the optical purity was 97.0% ee. In Table 1 below, “LA” represents polylactic acid.
-HPLC measurement conditions-
・ Column Optical resolution column, SUMICHIRAL OA5000 manufactured by Sumika Chemical Analysis Co., Ltd.
・ HPLC equipment: JASCO Corporation liquid chromatography column temperature: 25 ℃
-Composition of mobile phase 1.0 mM-copper (II) sulfate buffer / IPA = 98/2 (V / V)
(In this mobile phase, the ratio of copper (II) sulfate, IPA, and water is copper (II) sulfate / IPA / water = 156.4 mg / 20 mL / 980 mL).
・ Mobile phase flow rate 1.0mL / min ・ Detector UV detector (UV254nm)

<Measurement of physical properties of polymer piezoelectric film>
About the said polymeric piezoelectric film, melting | fusing point Tm, crystallinity, and internal haze were measured with the following method. In addition, the piezoelectric constant (stress-charge method) and the normalized molecular orientation MORc were measured by the methods described above. The results are shown in Table 1.

[Melting point Tm and crystallinity]
10 mg of the polymer piezoelectric film was accurately weighed and measured using a differential scanning calorimeter (DSC-1 manufactured by Perkin Elmer Co., Ltd.) at a temperature rising rate of 10 ° C./min to obtain a melting endotherm curve. The melting point Tm and the crystallinity were obtained from the obtained melting endotherm curve.

[Internal haze]
The internal haze (hereinafter also referred to as internal haze (H1)) of the polymer piezoelectric film was obtained by the following method.
First, a laminate in which only silicon oil (Shin-Etsu Silicone (trademark) manufactured by Shin-Etsu Chemical Co., Ltd., model number: KF96-100CS) is sandwiched between two glass plates is prepared, and the haze in the thickness direction of the laminate is prepared. (Hereinafter referred to as haze (H2)) was measured.
Next, a laminated body is prepared in which the polymer piezoelectric film having a surface uniformly coated with silicon oil is sandwiched between the two glass plates, and a haze in the thickness direction of the laminated body (hereinafter, haze ( H3)) was measured.
Next, the internal haze (H1) of the polymer piezoelectric film was obtained by taking these differences as in the following formula.
Internal haze (H1) = Haze (H3) -Haze (H2)

Here, the measurement of haze (H2) and haze (H3) was respectively performed using the following apparatus under the following measurement conditions.
Measuring device: manufactured by Tokyo Denshoku Co., Ltd., HAZE METER TC-HIIIDPK
Sample size: 30mm width x 30mm length
Measurement conditions: Conforms to JIS-K7105 Measurement temperature: Room temperature (25 ° C.)

[Example 1]
As solid content, 25 parts by mass of zirconium oxide fine particles having an average particle diameter of 0.02 μm, 75 parts by mass of urethane acrylate (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., Purple Light UV7600B) and a photopolymerization initiator (Ciba Specialty Chemicals Co., Ltd.) Manufactured by IRGACURE 184) was mixed with methyl ethyl ketone so that the solid content was 10% by mass to prepare a coating solution for a high refractive index layer.
As the zirconium oxide fine particles, a dispersion of zirconium oxide fine particles (ZRMEK 25% -F47 manufactured by CI Kasei Co., Ltd.) was used, and the dispersion was mixed so that the solid content was the above-mentioned parts by mass.
The high refractive index layer coating solution is applied to the polymer piezoelectric film produced by the above method with a wire bar, dried at 60 ° C. for 5 minutes, and then irradiated with ultraviolet light having an accumulated light amount of 400 mJ / cm ² with a metal halide lamp. Thus, a high refractive index layer was formed. The film thickness d1 of the high refractive index layer was 40 nm, and the refractive index n1 was 1.55.
Next, sputtering was performed on the surface of the high refractive index layer by adjusting the oxygen partial pressure using silicon as a target to form SiO ₂ having a film thickness of 40 nm and a refractive index of 1.46 as the low refractive index layer.
Furthermore, after masking a part of the low refractive index layer surface with a mending tape, sputtering was performed using indium oxide containing 36% by mass of tin oxide as a target with respect to the low refractive index layer surface. Then, the masking was peeled off, the part which has a transparent conductive layer, and the part which does not have a transparent conductive layer were formed, and the electrode pattern which consists of a transparent conductive layer was obtained. Thus, indium tin oxide (ITO) having an actual thickness of 15 nm and a refractive index of 1.95 was formed as a transparent conductive layer on a part of the low refractive index layer surface.
As described above, a laminate having a polymer piezoelectric film, a high refractive index layer, a low refractive index layer, and a transparent conductive layer in this order was obtained. The refractive index n1 and film thickness d1 of the high refractive index layer, the refractive index n2 and film thickness d2 of the low refractive index layer, and the refractive index n3 and film thickness d3 of the transparent conductive layer were measured by the following methods, respectively. The methods for measuring the refractive index and film thickness of Examples 2 to 7 and Comparative Example 1 are the same. The results are shown in Table 2.

-Measuring method of refractive index (high refractive index layer)-
(1) On a PET film (trade name “A4100”, manufactured by Toyobo Co., Ltd.) having a refractive index of 1.63, a coating solution for each high refractive index layer is applied by a dip coater (manufactured by Sugiyama Motochemical Co., Ltd.). The thickness of each layer was adjusted and applied so that the thickness after drying and curing was about 100 to 500 nm.
(2) After drying at 60 ° C. for 5 minutes, it was cured by irradiating with a metal halide lamp with an ultraviolet ray having an integrated light quantity of 400 mJ / cm ² . The back surface of the cured PET film was roughened with sandpaper, and the reflection spectrum was measured with a reflection spectral film thickness meter (trade name “FE-3000”, manufactured by Otsuka Electronics Co., Ltd.).
(3) From the reflectance read from the reflection spectrum, the constant of the wavelength dispersion formula (Formula 1) of n-Couchy shown below was obtained, and the refractive index at a wavelength of 550 nm was obtained.
N (λ) = a / λ4 + b / λ2 + c (Formula 1)

-Measuring method of refractive index (low refractive index layer)-
The refractive index n2 of the low refractive index layer was measured by the same method as the measuring method of the refractive index n1 of the high refractive index layer.

-Measuring method of refractive index (transparent conductive layer)-
The refractive index n3 of the transparent conductive layer was measured by the same method as the measuring method of the refractive index n1 of the high refractive index layer.

-Measuring method of film thickness (high refractive index layer)-
The film thickness d1 of the high refractive index layer was measured as follows. The laminate including the high refractive index layer was cut into a size of 1 mm × 10 mm and embedded in an epoxy resin for an electron microscope. This was fixed to a sample holder of an ultramicrotome, and a cross-sectional thin section parallel to the short side of the embedded sample piece was produced. Next, in a section where the thin film of this section is not significantly damaged, a transmission electron microscope (manufactured by JEOL, JEM-2010) is used to obtain a photograph at an acceleration voltage of 200 kV and a bright field at an observation magnification of 10,000 times. The film thickness was determined from the photograph taken.

-Film thickness measurement method (low refractive index layer)-
The film thickness d2 of the low refractive index layer was measured as follows. The laminate including the low refractive index layer was cut into a size of 1 mm × 10 mm and embedded in an epoxy resin for an electron microscope. This was fixed to a sample holder of an ultramicrotome, and a cross-sectional thin section parallel to the short side of the embedded sample piece was produced. Next, in a section where the thin film of this section is not significantly damaged, a transmission electron microscope (manufactured by JEOL, JEM-2010) is used to obtain a photograph at an acceleration voltage of 200 kV and a bright field at an observation magnification of 10,000 times. The film thickness was determined from the photograph taken.

-Measuring method of film thickness (transparent conductive layer)-
The film thickness d3 of the transparent conductive layer was measured as follows. The laminate including the transparent conductive layer was cut into a size of 1 mm × 10 mm and embedded in an epoxy resin for an electron microscope. This was fixed to a sample holder of an ultramicrotome, and a cross-sectional thin section parallel to the short side of the embedded sample piece was produced. Next, in a section where the thin film of this section is not significantly damaged, a transmission electron microscope (manufactured by JEOL, JEM-2010) is used to obtain a photograph at an acceleration voltage of 200 kV and a bright field at an observation magnification of 10,000 times. The film thickness was determined from the photograph taken.

[Example 2]
The amount of zirconium oxide fine particles having an average particle size of 0.02 μm in the coating solution for high refractive index layer is changed to 58 parts by mass, and the amount of urethane acrylate (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., purple light UV7600B) is changed to 42 parts by mass. A laminate was obtained in the same manner as in Example 1 except that. The high refractive index layer had a film thickness d1 of 40 nm and a refractive index n1 of 1.60.

Example 3
The amount of zirconium oxide fine particles having an average particle size of 0.02 μm in the high refractive index layer coating liquid is changed to 67 parts by mass, and the amount of urethane acrylate (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., purple light UV7600B) is changed to 33 parts by mass. A laminate was obtained in the same manner as in Example 1 except that. The high refractive index layer had a film thickness d1 of 40 nm and a refractive index n1 of 1.65.

Example 4
A laminate was obtained in the same manner as in Example 1 except that the thickness d1 of the high refractive index layer was changed to 60 nm by adjusting the coating thickness with a wire bar. The refractive index n1 of the high refractive index layer was 1.55.

Example 5
A laminate was obtained in the same manner as in Example 2 except that the thickness d1 of the high refractive index layer was changed to 20 nm by adjusting the coating thickness with a wire bar. The refractive index n1 of the high refractive index layer was 1.60.

Example 6
A laminate was obtained in the same manner as in Example 2 except that the thickness d1 of the high refractive index layer was changed to 60 nm by adjusting the coating thickness with a wire bar. The refractive index n1 of the high refractive index layer was 1.60.

Example 7
Example except that the high refractive index layer was formed after forming the first cured resin layer as the antiblock hard coat layer on both sides of the polymer piezoelectric film before forming the high refractive index layer by the following procedure. 1 to obtain a laminate. The film thickness d1 of the high refractive index layer was 40 nm, and the refractive index n1 was 1.55.
The first cured resin layer as the anti-block hard coat layer was prepared by applying an acrylic resin coating liquid (manufactured by Toyo Ink, anti-block hard coat LIODURAS TYAB-014) to the main surface of the polymer piezoelectric film with an applicator. It was formed by irradiating ultraviolet rays with an integrated light quantity of 1000 mJ / cm ² with a metal halide lamp after drying at 5 ° C. for 5 minutes. The film thickness of the first cured resin layer was 2 μm and the refractive index was 1.52. In addition, the refractive index and film thickness of the 1st cured resin layer were measured with the following method.
Moreover, about the obtained laminated body, as a result of measuring the thermal contraction rate when heated at 150 ° C. for 30 minutes in the MD direction (stretching direction) and the TD direction (direction orthogonal to the stretching direction), the MD direction is 1.1% and TD direction was 0.9%. The heat shrinkage rate was measured by the method described above.

-Measuring method of refractive index (first cured resin layer)-
A cured resin layer was formed on the glass plate, and measurement was performed according to JIS K 7142 using an Abbe refractometer (NAGO-4T, Na light source, wavelength: 589 nm, manufactured by Atago Co., Ltd.).

-Film thickness measurement method (first cured resin layer)-
The film thickness of the first cured resin layer is determined by the following formula using a digital length measuring device DIGIMICRO STAND MS-11C manufactured by Nikon Corporation.
Formula d = dt-dp
dt: Average thickness of 10 places of the laminate of the polymer piezoelectric film and the cured resin layer dt: Average thickness of 10 places of the polymer piezoelectric film before forming the cured resin layer or after removing the cured resin layer

[Comparative Example 1]
A laminate was obtained in the same manner as in Example 1 except that the high refractive index layer and the low refractive index layer were not formed.

<Evaluation of laminate>
For the laminates obtained in Examples 1 to 7 and Comparative Example 1, internal haze, total light transmittance difference, and b ^* difference were measured by the following methods. In addition, bone appearance was evaluated. The results are shown in Table 2.

[Internal haze]
In the measurement of the internal haze of the polymer piezoelectric film described above, the internal haze of the laminate was measured by the same method except that the polymer piezoelectric film was changed to the laminate of Examples 1 to 7 and Comparative Example 1.

[Total light transmittance difference]
Measure the total light transmittance of the portion where the transparent conductive layer is not formed by the masking of the laminate and the portion where the transparent conductive layer is formed, and calculate the absolute value of the difference of the total light transmittance as the total light transmittance difference. did.

[B ^* difference]
The b ^* of the part where the transparent conductive layer was not formed by the masking of the laminate and the part where the transparent conductive layer was formed was measured, and the difference between each b ^* was defined as the b ^* difference.
b ^* was measured using a color difference meter (“SQ-2000”, manufactured by Nippon Denshoku Industries Co., Ltd.). This b ^* is a value in the L ^* a ^* b color system defined in JIS Z 8729. In addition, it shows that the coloration by providing a transparent conductive layer is suppressed, so that b ^* difference is small.

[Bone appearance]
The boundary between the location where the transparent conductive layer was not formed and the location where the transparent conductive layer was formed by masking the laminate was visually confirmed and judged according to the following criteria.
A: The boundary was not confirmed and the bone appearance of the electrode pattern was remarkably suppressed. B: The boundary was hardly confirmed and the bone appearance was suppressed. C: The boundary was confirmed well and the bone appearance was remarkable. The

<Description of Table 2>
The first cured resin layer of Example 7 was provided on both surfaces of the polymer piezoelectric film. The film thickness of the cured resin layers on both sides is 2 μm.

As shown in Table 2, in this example, the total light transmittance difference in the part where the transparent conductive layer was not formed and the part where the transparent conductive layer was formed was smaller than in the comparative example.
In this example, the b ^* difference was small, and the bone appearance of the electrode pattern was suppressed in the bone appearance evaluation.
As a result, it was found that in this example, a decrease in transmittance due to the provision of the transparent conductive layer was suppressed, and coloration due to the provision of the transparent conductive layer was suppressed.
In particular, Examples 2 and 6 in which the film thickness d1 of the high refractive index layer is in the range of 25 nm to 80 nm are compared to Example 5 in which the film thickness d1 of the high refractive index layer is less than 25 nm, and b ^* It was found that both differences were reduced.
Further, Examples 1 and 2 in which the refractive index n1 of the high refractive index layer is in the range of 1.53 to 1.62 are compared with Example 3 in which the refractive index n1 of the high refractive index layer exceeds 1.62. ^{* The} difference became smaller and the bone appearance of the electrode pattern was further suppressed.
From the above, it was found that if the laminate of this example is used in a pressure detection device such as a touch panel, a decrease in contrast of the display image on the display is also suppressed.

10 polymer piezoelectric film, 11, 11A, 11B high refractive index layer, 12, 12A, 12B low refractive index layer, 14, 14A, 14B electrode pattern, 16 adhesive layer, 18 peelable release film, 20 peelable Protective film, 100, 101, 102, 104 Laminate

Claims (20)

Including a helical chiral polymer (A) having an optical activity with a weight average molecular weight of 50,000 to 1,000,000, crystallinity obtained by DSC method of 20% to 80%, and microwave transmission molecular orientation A polymer piezoelectric film in which the product of the normalized molecular orientation MORc and the crystallinity when the reference thickness measured by a meter is 50 μm is 40 to 700, and the internal haze for visible light is 5% or less; ,
A high refractive index layer;
A low refractive index layer;
A transparent conductive layer;
The laminated body which has these in this order. The refractive index n1 of the high refractive index layer is 1.50 to 2.20, the film thickness d1 of the high refractive index layer is 5 nm to 500 nm, and the refractive index n2 of the low refractive index layer is 1.30. 1.60, the film thickness d2 of the low refractive index layer is 5 nm to 500 nm, the refractive index n3 of the transparent conductive layer is 1.85 to 2.35, and the film thickness d3 of the transparent conductive layer is 5 nm to 200 nm,
n2 <n1 ≦ n3
The laminated body of Claim 1 satisfy | filling.   The refractive index n1 of the high refractive index layer is 1.50 to 1.70, the film thickness d1 of the high refractive index layer is 25 nm to 80 nm, and the refractive index n2 of the low refractive index layer is 1.40 to 40. 1.50, the film thickness d2 of the low refractive index layer is 10 nm to 80 nm, the refractive index n3 of the transparent conductive layer is 1.85 to 2.35, and the film thickness d3 of the transparent conductive layer is The layered product according to claim 1 or 2 which is 5 nm-60 nm.   The layered product according to any one of claims 1 to 3, wherein a refractive index n1 of the high refractive index layer is 1.53 to 1.62.   The laminate according to any one of claims 1 to 4, further comprising a cured resin layer between the polymer piezoelectric film and the high refractive index layer.   The laminate according to claim 5, wherein the cured resin layer is at least one of an easy adhesion layer, a hard coat layer, an antistatic layer, and an antiblock layer.   The laminate according to claim 5 or 6, wherein the cured resin layer is an active energy ray-cured resin that is a three-dimensional crosslinked resin and is cured by irradiation with active energy rays.   The refractive index of the said cured resin layer is 1.45 to 1.55, The laminated body of any one of Claims 5-7.   The laminated body according to any one of claims 5 to 8, wherein the refractive index of the cured resin layer is 1.46 to 1.52.   The laminate according to any one of claims 1 to 9, wherein a heat shrinkage rate when heated at 150 ° C for 30 minutes is 2.0% or less in both the MD direction and the TD direction.   Furthermore, it has an adhesive layer and a peelable release film in this order on the side opposite to the high refractive index layer when viewed from the polymer piezoelectric film. The laminated body of description.   The laminate according to claim 11, wherein the acid value of the adhesive layer is 0.01 mgKOH / g to 10 mgKOH / g.   The laminate according to claim 11 or 12, wherein a cured resin layer is provided between the polymer piezoelectric film and the adhesive layer.   Furthermore, the laminated body of any one of Claims 1-10 which has a peelable protective film on the opposite side to the said high refractive index layer seeing from the said polymer piezoelectric film.   The laminated body of Claim 14 which has a cured resin layer between the said polymeric piezoelectric film and the said peelable protective film. The piezoelectric polymer film, the stress at 25 ° C. - piezoelectric constant d ₁₄ measured by the charge method is 1 pC / N or more, the laminated body according to any one of claims 1 to 15. The helical helical polymer (A) is a polylactic acid polymer having a main chain containing a repeating unit represented by the following formula (1), according to any one of claims 1 to 16. Laminated body.

  The laminate according to any one of claims 1 to 17, wherein the helical chiral polymer (A) has an optical purity of 95.00% ee or higher.   The laminate according to any one of claims 1 to 18, wherein the polymer piezoelectric film has a content of the helical chiral polymer (A) of 80% by mass or more.   The polymer piezoelectric film comprises a stabilizer (B) having a weight average molecular weight of 200 to 60,000 having at least one functional group selected from the group consisting of a carbodiimide group, an epoxy group, and an isocyanate group. The laminated body of any one of Claims 1-19 containing 0.01 mass part-10 mass parts with respect to 100 mass parts of molecules (A).