TW202126715A - Transparent polyurethane and method for producing transparent polyurethane, thermosetting composition containing transparent polyurethane, and transparent conductive film - Google Patents

Abstract

To provide a transparent polyurethane having a low degree of coloration (yellowness), a production method therefor, a thermosetting composition containing the transparent polyurethane, and a transparent conductive film using a cured film obtained from the thermosetting composition as a protective film. The invention involves using as a synthesis solvent a solvent having an SP value of less than 9.80 by the Fedors estimation method to synthesize (A) a carboxy group-containing transparent polyurethane having a b* value of 0.25 or lower when formed into a 50 [mu]m-thick film. Next, a transparent base material and a transparent conductive layer on at least one surface of the transparent base material are provided, and a cured film obtained from a thermosetting composition containing (A) the carboxy group-containing transparent polyurethane, (B) an epoxy compound, and (C) a solvent is formed on the surface of the transparent conductive layer facing away from the transparent base material, thereby forming a transparent conductive film.

Description

Transparent polyurethane and its manufacturing method, and thermosetting composition and transparent conductive film containing transparent polyurethane

The present invention relates to transparent polyurethane and its manufacturing method, as well as a thermosetting composition containing transparent polyurethane and a transparent conductive film using the cured film as a protective film. In more detail, it relates to transparent polyurethane with a small degree of coloring (yellowness) and its manufacturing method, and a thermosetting composition containing transparent polyurethane and using its cured film as a protective film. Transparent conductive film.

Transparent conductive films are used in liquid crystal displays (LCD), plasma display panels (PDP), organic electroluminescent displays, transparent electrodes of solar cells (PV) and touch panels (TP), antistatic (ESD) films and electromagnetic waves Various fields such as shielding (EMI) film. As such transparent conductive thin films, those using ITO (Indium Tin Oxide) have been used in the past, but there are problems in that the supply stability of indium is low, the manufacturing cost is high, the flexibility is lacking, and the high temperature is required for film formation. Therefore, the search for a transparent conductive film to replace ITO is actively carried out. Among them, transparent conductive films containing metal nanowires are suitable as a substitute for ITO due to their excellent conductivity, optical properties and flexibility, can be formed by wet processes, low manufacturing costs, and do not need to be at high temperatures during film formation. Transparent conductive film. For example, a transparent conductive film containing silver nanowires and having high conductivity, optical properties, and flexibility is known (refer to Patent Document 1).

However, the transparent conductive film containing silver nanowires has the problem of lack of environmental resistance due to the large surface area per mass of silver, which is easy to react with various compounds. The influence of oxygen or moisture in the air, etc., and the corrosion of nanostructures can easily reduce the conductivity. In addition, especially in applications such as electronic materials, in order to prevent the adhesion or mixing of fine particles, dust or dust, etc. on the surface of the substrate, a physical cleaning step using a brush or the like is used in most cases, but this step also causes the surface The problem of damage.

In order to solve this, various protective films have been explored. The protective film that functions as a transparent conductive film must also be transparent. On the other hand, the resin used in the protective film is generally known to cause so-called yellowing. The yellowing condition leads to the degradation of the performance as a transparent conductive film (the image quality of the display and the photoelectric conversion efficiency of the solar cell are reduced).

Patent Document 2 discloses a polyurethane elastomer suitable for optical films synthesized using a material with a specific skeleton (polyisocyanate containing 1,4-bis(isocyanatomethyl)cyclohexane), mainly The description is excellent in both transparency and yellowing resistance. In addition, Patent Document 3 discloses a method for producing a transparent polyurethane resin suitable for optical-related applications that has low hardness, flexibility and elasticity, and does not bleed out of plasticizers and/or solvents. Patent Document 4 It discloses a transparent coating made of soft polyurethane with anti-fogging effect. These are all synthesized by mixing raw materials with a specific chemical structure in a specific ratio to obtain transparent polyurethane, but it is related to the use of independent sheets or films, molded products or to improve other transparent glass or The mechanical properties of the plastic substrate, the use of a coating material for wettability (anti-fogging), and the function of a protective film that imparts environmental resistance (temperature, humidity, natural light) to the transparent conductive film are not mentioned. [Prior Technical Literature] [Patent Literature]

Patent Document 1: Japanese Special Publication No. 2010-507199 Patent Document 2: Japanese Patent Application Publication No. 2011-236329 Patent Document 3: Japanese Patent Application Publication No. 2005-272676 Patent Document 4: Japanese Patent Application Laid-Open No. 2-20580

[The problem to be solved by the invention]

The subject of the present invention is to provide a transparent polyurethane with a small degree of coloring (yellowness), a method of producing the same, a thermosetting composition containing the transparent polyurethane, and a cured film using the transparent polyurethane as a protective film. Transparent conductive film. [Means to solve the problem]

The inventors found that even if the monomers used to synthesize polyurethane are the same, by synthesizing under specific synthesis conditions, polyurethane with low coloring and better transparency can be obtained, which is suitable for It is used as a protective film for transparent conductive layer of transparent conductive film.

That is, the present invention has the following aspects.

[1] A (A) carboxyl group-containing transparent polyurethane, characterized in that the b* value when the film is formed to a thickness of 50 μm is 0.25 or less.

[2] As in [1], (A) carboxyl group-containing transparent polyurethane, wherein the aforementioned (A) carboxyl group-containing transparent polyurethane uses (a1) polyisocyanate compound and (a2) polybasic An alcohol compound and (a3) a carboxyl group-containing dihydroxy compound are synthesized as monomers.

[3] As in [2], (A) carboxyl group-containing transparent polyurethane, wherein the aforementioned (a2) polyol compound is a polycarbonate polyol.

[4] The (A) carboxyl group-containing transparent polyurethane as in [2] or [3], wherein the (a1) polyisocyanate compound is an aliphatic polyisocyanate or an alicyclic polyisocyanate.

[5] A thermosetting composition comprising (A) a carboxyl group-containing transparent polyurethane with a b* value of 0.25 or less when the film is formed to a thickness of 50 μm, (B) an epoxy compound, and (C) Solvent.

[6] The thermosetting composition as in [5], which further contains (D) a curing accelerator.

[7] The thermosetting composition according to [5] or [6], wherein the epoxy compound (B) is a multifunctional epoxy compound having 3 or more epoxy groups in one molecule.

[8] A transparent conductive film, which has a transparent substrate, a transparent conductive layer provided on at least one surface of the transparent substrate, and a protective film provided on the side of the transparent conductive layer opposite to the transparent substrate, characterized by A cured film of the aforementioned protective film-based thermosetting composition, the thermosetting composition comprising (A) carboxyl-containing transparent polyurethane, ( B) Epoxy compound and (C) solvent.

[9] The transparent conductive film of [8], wherein the transparent conductive layer includes metal nanowires.

[10] The transparent conductive film as in [9], wherein the aforementioned metal nanowire is silver nanowire.

[11] A manufacturing method of (A) carboxyl-containing transparent polyurethane as described in any one of [1] to [4], which is characterized by using Fedors’ inferred algorithm with an SP value of less than 9.80 The solvent is used as a synthetic solvent.

[12] The method for producing transparent polyurethane as in [11], wherein the aforementioned solvent is selected from the group consisting of diethanol monobutyl ether acetate, 1,4-butanediol diacetate, and tripropylene glycol dimethyl Ether, propylene glycol dimethyl ether, diethylene glycol dibutyl ether, triethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, tripropylene glycol dimethyl ether, n-propyl acetate, n-butyl acetate, 1,4-di Any of the group consisting of oxane, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, isophorone, tetrahydrofuran, 4-methyltetrahydropyran, and cyclopentyl methyl ether By.

[13] The method for producing transparent polyurethane as in [11], wherein the aforementioned solvent is 4-methyltetrahydropyran or triethylene glycol dimethyl ether.

[14] The method for producing transparent polyurethane according to [11], wherein the aforementioned solvent is methyltetrahydropyran. [Effects of the invention]

According to the present invention, it is possible to provide a transparent polyurethane with a small degree of coloring (yellowness), a method for producing the same, a thermosetting composition containing the transparent polyurethane, and a cured film using the transparent polyurethane as a protective film. Transparent conductive film.

Hereinafter, a mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described.

<Transparent polyurethane and thermosetting composition containing it> The characteristic film of (A) carboxyl group-containing transparent polyurethane in one aspect of the present invention has a b* value of 0.25 or less when the film is formed to have a thickness of 50 μm.

As the resin that forms the protective film of the transparent conductive film, if it is a resin with high insulation performance and environmental resistance (temperature, humidity, natural light, etc.), it can be used without special problems, but if it is considered suitable for flexible displays , It is suitable for polyurethane with a moderately soft skeleton. In addition, in order to prevent damage to the transparent conductive layer constituting the transparent conductive film, it is preferably a curable resin having a crosslinking group that can be cured after being coated on the transparent conductive layer. After the protective film is formed on the transparent conductive layer, the curing of the cross-linking reaction group is performed, which is preferable because the scratch resistance and solvent resistance can be improved. As the crosslinking reactive group, considering the resistance to natural light, a thermally hardened crosslinking reactive group is preferred.

Among these thermosetting resins, (A) carboxyl group-containing transparent polyurethane has flexibility. By blending with a compound having an epoxy group or an isocyanate group, the crosslinking reaction group (Epoxy group or isocyanate group) can crosslink with the carboxyl group of (A) carboxyl-containing transparent polyurethane, so it is more preferable.

(A) The carboxyl-containing transparent polyurethane can be synthesized from polyol compounds, polyisocyanate compounds, and carboxyl-containing dihydroxy compounds.

The protective film of the transparent conductive film is preferably formed by printing and coating a thermosetting composition containing (A) a carboxyl group-containing transparent polyurethane on the transparent conductive layer, and by making it Hardened and formed. The thermosetting composition preferably contains (A) a carboxyl group-containing transparent polyurethane, (B) an epoxy compound, and (C) a solvent, and may further contain (D) a curing accelerator if necessary.

The above-mentioned (A) carboxyl group-containing transparent polyurethane has a weight average molecular weight of preferably 1,000 to 100,000, more preferably 2,000 to 70,000, and still more preferably 3,000 to 50,000. Here, the molecular weight is a value in terms of polystyrene measured by a gel permeation chromatograph (hereinafter referred to as GPC). When the weight average molecular weight is less than 1,000, the elongation, flexibility and strength of the coating film after printing will be impaired. When it exceeds 100,000, the solubility of polyurethane in solvents is reduced, because even the solubility viscosity is too high. High, so there is a limit to the use of the surface becomes larger.

In this manual, unless otherwise specified, the measurement conditions of GPC are as follows. Device name: HPLC unit HSS-2000 manufactured by JASCO Corporation String: Shodex string LF-804 Mobile phase: Tetrahydrofuran Flow rate: 1.0mL/min Detector: RI-2031Plus manufactured by JASCO Corporation Temperature: 40.0℃ Sample quantity: sample circulation 100μL Sample concentration: Prepared to be about 0.1% by mass

(A) The acid value of the carboxyl-containing transparent polyurethane is preferably 10 to 140 mg-KOH/g, more preferably 15 to 130 mg-KOH/g. When the acid value is less than 10 mg-KOH/g, not only the curability will be lowered, but the solvent resistance will also be worsened. If it exceeds 140 mg-KOH/g, the urethane resin has low solubility in solvents, and even if it dissolves, the viscosity becomes too high, making it difficult to handle. In addition, since the cured product becomes too hard, it is easy to cause problems such as warpage due to the base film.

In addition, in this specification, the acid value of the resin is the value measured by the following method. In a 100ml Erlenmeyer flask, approximately 0.2g of the sample was accurately weighed with a precision balance, and 10ml of a mixed solvent of ethanol/toluene=1/2 (mass ratio) was added and dissolved. Furthermore, 1 to 3 drops of a phenolphthalein ethanol solution as an indicator are added to the container, and the mixture is sufficiently stirred until the sample becomes uniform. It is titrated with 0.1N potassium hydroxide-ethanol solution, and the neutralization end point is when the reddish color of the indicator lasts for 30 seconds. From this result, the value obtained by the following calculation formula is used as the acid value of the resin. Acid value (mg-KOH/g)=[B×f×5.611]/S B: Usage amount of 0.1N potassium hydroxide-ethanol solution (ml) f: 0.1N potassium hydroxide-ethanol solution factor S: The amount of sample taken (g)

More specifically, (A) a carboxyl-containing transparent polyurethane is a polyisocyanate compound, (a2) a polyol compound, and (a3) a carboxyl-containing dihydroxy compound synthesized as monomers. Urethane. From the viewpoint of light resistance, it is desirable that each of (a1), (a2), and (a3) does not contain conjugated functional groups such as aromatic compounds. The following is a more detailed description of each monomer.

(a1) Polyisocyanate compound (A1) The polyisocyanate compound is preferably a diisocyanate having two isocyanate groups per molecule. As a polyisocyanate compound, an aliphatic polyisocyanate, an alicyclic polyisocyanate, etc. are mentioned, 1 type of these may be used individually or in combination of 2 or more types. (A) In the range where the carboxyl group-containing transparent polyurethane does not gel, a small amount of polyisocyanate having 3 or more isocyanate groups can also be used.

Examples of aliphatic polyisocyanates include 1,3-trimethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, and 1,9-nonamethylene diisocyanate , 1,10-decamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2,2'-Diethyl ether diisocyanate, dimer acid diisocyanate, etc.

As alicyclic polyisocyanate, for example, 1,4-cyclohexane diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, 1,4-bis(isocyanatomethyl) ring Hexane, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (IPDI, isophorone diisocyanate), bis-(4-isocyanatocyclohexyl) methane (hydrogenated MDI) ), hydrogenated (1,3- or 1,4-) xylene diisocyanate, norbornane diisocyanate (NBDI), etc.

Here, as the (a1) polyisocyanate compound, by using an alicyclic compound having 6 to 30 carbon atoms other than the carbon atoms in the isocyanate group (-NCO group), the polyaminomethyl The protective film formed by acid ester resin has high reliability especially at high temperature and high humidity, which is beneficial to the components of electronic equipment.

As the (a1) polyisocyanate compound, an aromatic or araliphatic polyisocyanate compound having an aromatic ring can also be used, but from the viewpoint of weather resistance and light resistance, it is preferable to use a polyisocyanate compound that does not have an aromatic ring as the (a1) polyisocyanate compound Compound. In the case of using aromatic polyisocyanate and aromatic aliphatic polyisocyanate, in (a1) polyisocyanate compound, relative to the total amount (100 mol%) of (a1) polyisocyanate compound, the content is 50 mol% or less, preferably 30 mol% or less , More preferably less than 10mol%.

(a2) Polyol compound (a2) The number average molecular weight (catalog value) of the polyol compound (but in (a2) the polyol compound does not contain the (a3) carboxyl-containing dihydroxy compound described later) is usually 250 to 50,000, preferably 400 to 10,000, more preferably 500~5,000.

(a2) The polyol compound is preferably a diol compound having hydroxyl groups at both ends. Examples are polycarbonate polyol, polyether polyol, polyester polyol, and polylactone polyol. Among these, considering the balance of water resistance, insulation reliability, and adhesion to the substrate as a protective film, a polycarbonate polyol is preferable.

The polycarbonate polyol can be obtained by reacting a diol having 3 to 18 carbon atoms as a raw material with a carbonate ester or carbon chloride, and is represented by, for example, the following structural formula (1).

In formula (1), R ³ is the residue after removing the hydroxyl group from the corresponding diol (HO-R ³ _{-OH), and n 3} is a positive integer, preferably 2-50.

The polycarbonate polyol represented by formula (1) can be specifically used by using 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3- Methyl-1,5-pentanediol, 1,8-octanediol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 1,9-nonanediol, 2-methyl Benzyl-1,8-octanediol, 1,10-decamethylene glycol, 1,2-tetradecanediol, etc. are produced as raw materials.

The above-mentioned polycarbonate polyol may also be a polycarbonate polyol (copolymerized polycarbonate polyol) having a plurality of alkylene groups in its skeleton. The use of copolymerized polycarbonate polyols is often advantageous from the viewpoint of preventing (A) carboxyl group-containing transparent polyurethane from crystallization. In addition, considering solubility in solvents, it is preferable to use a polycarbonate polyol having a branched skeleton and a hydroxyl group at the end of the branched chain in combination.

The above-mentioned polyether polyol compound is the dehydration condensation of diols with 2-12 carbon atoms, or the ring-opening of oxirane compounds, oxetane compounds, or tetrahydrofuran compounds with 2-12 carbon atoms The polymerization product is represented by the following structural formula (2), for example.

In formula (2), R ⁴ is the residue after removing the hydroxyl group from the corresponding diol (HO-R ⁴ _{-OH), and n 4} is a positive integer, preferably 4-50. The above-mentioned diols having 2 to 12 carbon atoms may be used alone to form a homopolymer, or two or more of them may be used in combination to form a copolymer.

As the polyether polyol represented by the above formula (2), specific examples are polyethylene glycol, polypropylene glycol, poly-1,2-butanediol, polytetramethylene glycol (poly1,4-butanediol ), poly-3-methyltetramethylene glycol, polyneopentyl glycol and other polyalkylene glycols. Moreover, for the purpose of improving the hydrophobicity of polyether polyols, these copolymers, such as copolymers of 1,4-butanediol and neopentyl glycol, can also be used.

The above-mentioned polyester polyol is obtained by dehydration condensation of dicarboxylic acid and diol, or transesterification reaction between esterification of dicarboxylic acid and lower alcohol and diol, and is represented by, for example, the following structural formula (3).

In formula (3), R ⁵ is the residue after removing the hydroxyl group from the corresponding diol (HO-R ^{5 -OH), and R 6} is the residue after removing 2 carboxyl groups from the corresponding dicarboxylic acid (HOCO-R ^{6 -COOH)} For the following residues, n ₅ is a positive integer, preferably 2-50.

As the above-mentioned glycol (HO-R ⁵ -OH), specific examples are ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1, 4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,8-octanediol, 1,3-cyclohexane Dimethanol, 1,4-cyclohexanedimethanol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 1,10-decamethylene glycol or 1,2-dec Tetraalkylene glycol, 2,4-Diethyl-1,5-pentanediol, butylethylpropanediol, 1,3-cyclohexanedimethanol, diethylene glycol, triethylene glycol, dipropylene glycol, etc. .

Moreover, as the above-mentioned dicarboxylic acid (HOCO-R ⁶ -COOH), specific examples are succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, decane dicarboxylic acid, tridecane dicarboxylic acid, 1,4-Cyclohexanedicarboxylic acid, hexahydrophthalic acid, methyl tetrahydrophthalic acid, endomethylene tetrahydrophthalic acid, methyl endomethylene tetrahydrophthalic acid, chlorosonic acid (Chloredic acid), fumaric acid, maleic acid, itaconic acid, citraconic acid.

The above-mentioned polylactone polyol is obtained by the condensation reaction of the ring-opening polymer of lactone and diol, or the condensation reaction of diol and hydroxyalkanoic acid, for example, it is represented by the following structural formula (4).

In formula (4), R ⁷ is the residue after removing the hydroxyl group and carboxyl group from the corresponding hydroxyalkanoic acid (HO-R ^{7 -COOH), and R 8} is removing the hydroxyl group from the corresponding diol (HO-R ⁸ -OH) For the following residues, n ₆ is a positive integer, preferably 2-50. As the diol (HO-R ⁸ -OH) is the same as the example of the diol (HO-R ⁵ -OH) persons.

Specific examples of the hydroxyalkanoic acid (HO-R ⁷ -COOH) include 3-hydroxybutyric acid, 4-hydroxyvaleric acid, 5-hydroxycaproic acid, and the like. The lactone is exemplified by ε-caprolactone.

(a3) Dihydroxy compound containing carboxyl group As (a3) the carboxyl-containing dihydroxy compound can control the cross-linking point, it is preferable to have two selected from hydroxyl groups and hydroxyalkyl groups having 1 or 2 carbon atoms and having a molecular weight of 200 or less The carboxylic acid or amino carboxylic acid. Specific examples are 2,2-dimethylolpropionic acid (DMPA), 2,2-dimethylolbutanoic acid (DMBA), N,N-bishydroxyethylglycine, N,N-bishydroxyethyl Among them, 2,2-dimethylolpropionic acid and 2,2-dimethylolbutanoic acid are particularly preferred based on solubility in solvents. These (a3) carboxyl group-containing dihydroxy compounds can be used individually by 1 type or in combination of 2 or more types.

The aforementioned (A) carboxyl group-containing transparent polyurethane can be synthesized from only the above three components ((a1), (a2) and (a3)). Furthermore, it can also react with (a4) a monohydroxy compound and/or (a5) a monoisocyanate compound to synthesize. From the viewpoint of light resistance, it is preferable to use a compound that does not contain an aromatic ring or a carbon-carbon double bond in the molecule.

(a4) Monohydroxy compound The (a4) monohydroxy compound is exemplified by compounds having a carboxylic acid such as glycolic acid and hydroxypivalic acid.

(a4) The monohydroxy compound can be used individually by 1 type or in combination of 2 or more types.

In addition, examples of (a4) monohydroxy compounds include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, pentanol, hexanol, octanol, etc. .

(a5) Monoisocyanate compound (A5) Monoisocyanate compounds are exemplified by hexyl isocyanate, dodecyl isocyanate, and the like.

The above-mentioned (A) carboxyl-containing transparent polyurethane can be made by using a suitable organic solvent in the presence or absence of a conventional urethane catalyst such as dibutyltin dilaurate. (a1) Polyisocyanate compound, (a2) polyol compound, and (a3) carboxyl group-containing dihydroxy compound are synthesized by reaction. However, if the reaction is done without a catalyst, it is not necessary to consider the final tin etc. mixing and it is more suitable.

The organic solvent used when synthesizing the above-mentioned (A) carboxyl-containing transparent polyurethane has low reactivity with isocyanate compounds and does not reduce the solubility of the resulting polyurethane, preferably without Basic functional groups such as amines have a boiling point of 50°C or higher, preferably 80°C or higher, and more preferably 100°C or higher. In addition, it is preferable to use a solvent with an SP value less than 9.80 by Fedors's calculation. The value of SP (Solubility Parameters) is the value of the solubility standard of a 2-component system solution, and substances with similar SP values tend to be easily mixed.

The SP value (δ) is proposed by Hildebrand and Scott by the regular solution (the cohesive force between the solute and the solvent is only the London dispersion force (Van der Waals force in the narrow sense), and there is no Electrostatic interaction, association (hydrogen bond), dipole interaction, etc. The theory of action is a value defined by the square root of the aggregation energy density as shown in the following formula. δ=(ΔE/V) ^1/2 =[(ΔH-RT)/V)] ^1/2 where V is the molecular volume of the solvent, ΔE is the condensation energy (evaporation energy), ΔH is the enthalpy of evaporation, and R is the gas Constant, T represents absolute temperature. The SI units of SP value are (J/cm ³ ) ^1/2 , (MPa) ^1/2 , but in this manual, the conventionally used (cal/cm ³ ) ^{1/2 is used} . The SP value is calculated from the latent heat of evaporation necessary to evaporate ^{1 cm 3 of liquid.}

Although the SP value defined above is limited to a known liquid whose boiling point can be measured, it is not inconsistent with the method of measuring the solubility of the polymer in a solvent with a known SP value for the purpose of being applicable to polymers or various compounds, etc. Way to export. As one of the SP value estimation algorithms, there is Fedors' estimation algorithm.

Fedors believes that both the agglutination energy density and the molar volume depend on the type and number of substituents, and proposes the following formula and specific constants per substituent. _{δ = [(Σe i) /} Σv i)] 1/2 where, Σe _i represents a cohesive energy, Σv _i represents a mole molecular volume. The unit of agglutination energy is J/mol in most cases, but the cal/mol used in the past is used in this manual.

As an example, a calculation example of 1-octanol is shown. Since the system of _{-CH 3 (e i = 1125 cal} / mol, v i = 33.5cm 3 / mol) as a _{unit, -CH 2 - (e i =} 1180cal / mol, v i = 16.1 cm 3 / mol) 7 _{units, -OH (e i = 7120cal /} mol, v i = 10.0cm 3 / mol) is a unit constituted, so _{Σe i = 1125 × 1 + 1180} × 7 + 7120 × 1 = 16505cal / mol , Σv _i =33.5×1+16.1×7+10.0×1=156.2cm ^{3 /} mol, δ ^=(16505/ 156.2) 1/2 =10.28(cal/cm ³ ) ^1/2 .

Fedors method and estimation of the specific constant (e _i, v _i) of each substituent group described in RF Fedors:... Polym Eng Sci, 14 [2], 147-154 (1974).

The inventors used various solvents to perform the synthesis of (A) carboxyl-containing transparent polyurethane, and found that the color tone of (A) carboxyl-containing transparent polyurethane is different depending on the solvent used. . That is, it was found that (A) a transparent carboxyl-containing polyurethane with a smaller yellowness (b* value) was obtained by using the solvent whose SP value was less than 9.80 by Fedors's calculation.

The SP value is more preferably 7.00 or more and less than 9.50, and still more preferably 7.50 or more and less than 9.00. Examples of solvents whose SP value does not reach 9.80 by Fedors's calculation are propylene glycol monomethyl ether acetate (SP value 8.73), diethanol monoethyl ether acetate (SP value 9.01), and diethanol monobutyl ether acetic acid Ester (SP value 8.94), 1,4-butanediol diacetate (SP value 9.64), tripropylene glycol dimethyl ether (SP value 8.06), or propylene glycol dimethyl ether (SP value 7.52), diethylene glycol Dimethyl ether (SP value 8.10), diethylene glycol dibutyl ether (SP value 8.29), triethylene glycol dimethyl ether (SP value 8.37), dipropylene glycol dimethyl ether (SP value 7.88), tripropylene glycol dimethyl ether Ether (SP value 8.06), n-propyl acetate (SP value 8.72), n-butyl acetate (SP value 8.70), 1,4-dioxane (SP value 8.64), methyl ethyl ketone (SP value 8.98) , Methyl isobutyl ketone (SP value 8.68), diisobutyl ketone (SP value 8.50), isophorone (SP value 9.20), tetrahydrofuran (SP value 8.28), 4-methyltetrahydropyran (SP Value 8.13), cyclopentyl methyl ether (SP value 8.13) and so on. Among them, diethanol monobutyl ether acetate, 1,4-butanediol diacetate, tripropylene glycol dimethyl ether, propylene glycol dimethyl ether, diethylene glycol dibutyl ether, and triethylene glycol are preferred. Dimethyl ether, dipropylene glycol dimethyl ether, tripropylene glycol dimethyl ether, n-propyl acetate, n-butyl acetate, 1,4-dioxane, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl Base ketone, isophorone, tetrahydrofuran, 4-methyltetrahydropyran, cyclopentyl methyl ether. As will be described later, if triethylene glycol dimethyl ether or 4-methyltetrahydropyran is used as the synthesis solvent, a transparent synthesis solution can be obtained, which is preferable for the production of transparent polyurethane. A more preferred solvent is 4-methyltetrahydropyran.

The order of feeding the raw materials when synthesizing the above (A) carboxyl-containing transparent polyurethane is not particularly limited, but usually (a2) polyol compound and (a3) carboxyl-containing dihydroxy compound are fed first, After dissolving or dispersing in the above solvent, add it while dropping (a1) polyisocyanate compound at 20~150℃, more preferably 60~120℃, and then add it at 30~160℃, more preferably 50~130℃ The reaction.

The feeding molar ratio of the raw materials is adjusted according to the molecular weight and acid value of the intended polyurethane. However, when the polyurethane is introduced into the monohydroxy compound (a4), the polyamine must be The end of the carbamic acid ester molecule becomes an isocyanate group. Compared with (a2) polyol compound and (a3) carboxyl-containing dihydroxy compound, (a1) polyisocyanate compound is used in excess (isocyanate group). More excess than the total of hydroxyl groups). When (a5) a monoisocyanate compound is introduced into the polyurethane, it is necessary to make the end of the polyurethane molecule become a hydroxyl group, so that (a1) the polyisocyanate compound is less than (a2) the polyol compound and (a3) Use as a carboxyl group-containing dihydroxy compound (isocyanate groups are less than the total number of hydroxyl groups).

Specifically, the isocyanate groups fed into the molar ratio (a1) polyisocyanate compound: ((a2) the hydroxyl group of the polyol compound + (a3) the hydroxyl group of the carboxyl-containing dihydroxy compound) is 0.5~ 1.5:1, preferably 0.8~1.2:1, more preferably 0.95~1.05:1.

In addition, (a2) the hydroxyl group of the polyol compound: (a3) the hydroxyl group of the carboxyl-containing dihydroxy compound is 1:0.1-30, preferably 1:0.3-10.

In the case of using (a4) monohydroxy compound, the molar number of (a1) polyisocyanate compound is more excessive than that of ((a2) polyol compound + (a3) carboxyl-containing dihydroxy compound) , (A4) The monohydroxy compound is preferably used in an excess molar amount relative to the isocyanate group, which is 0.5 to 1.5 times the molar amount, preferably 0.8 to 1.2 times the molar amount.

In the case of using (a5) monoisocyanate compound, the molar number of ((a2) polyol compound + (a3) carboxyl-containing dihydroxy compound) is more excessive than that of (a1) polyisocyanate compound, Preferably, the molar excess relative to the hydroxyl group is 0.5 to 1.5 times the molar amount, preferably 0.8 to 1.2 times the molar amount.

In order to introduce (a4) monohydroxy compound into (A) carboxyl group-containing transparent polyurethane, for the reaction of (a2) polyol compound and (a3) carboxyl group-containing dihydroxy compound and (a1) polyisocyanate compound At about the end of time, react the remaining isocyanate groups on both ends of (A) carboxyl-containing transparent polyurethane with (a4) monohydroxy compound, and in the reaction solution at 20~150℃, more preferably The (a4) monohydroxy compound is dropped at 70~120°C, and then the reaction is completed by keeping it at the same temperature.

In order to introduce (a5) monoisocyanate compound into (A) carboxyl group-containing transparent polyurethane, for the reaction between (a2) polyol compound and (a3) carboxyl group-containing dihydroxy compound and (a1) polyisocyanate compound At approximately the end of the time, the remaining hydroxyl groups on both ends of (A) carboxyl-containing transparent polyurethane are reacted with (a5) monoisocyanate compound in the reaction solution at 20~150℃, preferably 50~120 The (a5) monoisocyanate compound was dropped at °C, and then maintained at the same temperature to complete the reaction.

As the above-mentioned (B) epoxy compound, bisphenol A type epoxy compound, hydrogenated bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolak type epoxy resin, phenol novolak type epoxy resin can be exemplified. Resin, cresol novolac type epoxy resin, N-glycidyl type epoxy resin, bisphenol A novolac type epoxy resin, xylenol type epoxy resin, glyoxal type epoxy resin, containing amine group Epoxy resin, rubber modified epoxy resin, dicyclopentadiene phenol type epoxy resin, silicone modified epoxy resin, ε-caprolactone modified epoxy resin, aliphatic epoxy containing glycidyl group Epoxy compounds having two or more epoxy groups in one molecule, such as resins and alicyclic epoxy resins containing glycidyl groups.

In particular, it is more suitable to use a multifunctional epoxy compound having 3 or more epoxy groups in one molecule. Examples of these epoxy compounds are, for example, EHPE (registered trademark) 3150 (made by DAICEL Co., Ltd.), jER (registered trademark) 604 (made by Mitsubishi Chemical Co., Ltd.), EPICLON (registered trademark) EXA-4700 (DIC Co., Ltd.) Company product), EPICLON (registered trademark) HP-7200 (manufactured by DIC Co., Ltd.), pentaerythritol tetraglycidyl ether, pentaerythritol triglycidyl ether, TEPIC (registered trademark)-S (manufactured by Nissan Chemical Co., Ltd.), etc.

(A) The mixing ratio of carboxyl group-containing transparent polyurethane relative to the above-mentioned (B) epoxy compound is based on the equivalent of the carboxyl group in the polyurethane relative to the epoxy group of the epoxy compound (B) The ratio is preferably 0.5 to 1.5, more preferably 0.7 to 1.3, and still more preferably 0.9 to 1.1.

As the above-mentioned (D) hardening accelerator, phosphine compounds such as triphenylphosphine and tributylphosphine (manufactured by Beixing Chemical Industry Co., Ltd.), CURAZOLE (registered trademark) (imidazole-based epoxy resin hardener: Shikoku Kasei Industrial Co., Ltd.), 2-phenyl-4-methyl-5-hydroxymethylimidazole, U-CAT (registered trademark) SA series (DBU salt: manufactured by SAN APRO Co., Ltd.), U-CAT (registered Trademark) 5003 (phosphine compound: manufactured by SAN APRO Co., Ltd.) and the like. As for these usage amounts, if the usage amount is too small, there will be no additive effect, and if the usage amount is too much, the electrical insulation will decrease. Therefore, relative to the total mass of (A) and (B), use 0.1-10% by mass, more preferably 0.5 to 6 mass%, more preferably 0.5 to 5 mass%, particularly preferably 0.5 to 3 mass%.

Moreover, a hardening auxiliary agent can also be used together. Examples of curing aids include polyfunctional thiol compounds, oxetane compounds, and the like. Examples of polyfunctional thiol compounds include pentaerythritol tetrakis (3-mercaptopropionate), tris-[(3-mercaptopropionyloxy)-ethyl]-isocyanurate, trimethylolpropane tris (3 -Mercaptopropionate), CURRANTS (registered trademark) MT series (manufactured by Showa Denko Co., Ltd.), etc. Examples of the oxetane compound include ARON OXETANE (registered trademark) series (manufactured by Toagosei Co., Ltd.), ETERNACOLL (registered trademark) OXBP or OXMA (manufactured by Ube Industries Co., Ltd.). As for these usage amounts, if the usage amount is too small, there will be no additive effect. If the usage amount is too much, the curing speed will be too fast and the handling properties will decrease. Therefore, relative to the quality of (B), it is better to use 0.1-10% by mass, more preferably Use 0.5-6 mass%.

The thermosetting composition (sometimes called protective film ink) preferably contains (C) a solvent of 95.0% by mass or more and 99.9% by mass, more preferably 96% by mass or more and 99.7% by mass or less, and still more preferably 97% by mass % Or more and 99.5 mass% or less. As the (C) solvent, it is preferable to directly use the solvent used in the synthesis of (A) carboxyl-containing transparent polyurethane, but in order to adjust the solubility or printability of the polyurethane resin, other solvents can also be used. Solvent. Other solvents that can be used can also be solvents outside the SP value range of the preferred solvent used in the synthesis of (A) carboxyl-containing transparent polyurethane. In consideration of the stability of the thermosetting composition for the protective film, the boiling point of the solvent is preferably 60°C to 300°C, more preferably 70°C to 250°C. If the boiling point is less than 60°C, it is easy to dry during printing, and it is easy to produce unevenness. When the boiling point is higher than 300°C, it is not conducive to industrial production due to the need for long-term heating treatment at high temperature during drying and hardening.

As these solvents, propylene glycol monomethyl ether acetate (boiling point 146°C), γ-butyrolactone (boiling point 204°C), diethylene glycol monoethyl ether acetate (boiling point 218°C), and tripropylene glycol dimethyl ether acetate can be used. Solvents used in the synthesis of polyurethanes such as ether (boiling point 243°C), or ether solvents such as propylene glycol dimethyl ether (boiling point 97°C) and diethylene glycol dimethyl ether (boiling point 162°C), etc. Propanol (boiling point 82℃), tertiary butanol (boiling point 82℃), propylene glycol monomethyl ether (boiling point 120℃), 1-hexanol (boiling point 151℃), diethylene glycol monomethyl ether (boiling point 194℃) , Diethylene glycol monoethyl ether (boiling point 196℃), diethylene glycol monobutyl ether (boiling point 230℃), triethylene glycol (boiling point 276℃), ethyl lactate (boiling point 154℃) and other hydroxyl-containing solvents, Methyl ethyl ketone (boiling point 80°C), ethyl acetate (boiling point 77°C), n-propyl acetate (boiling point 102°C). These solvents may be used individually by 1 type, and may mix and use 2 or more types. When mixing two or more types, in addition to the solvent used in the synthesis of (A) carboxyl-containing transparent polyurethane, considering the solubility of the polyurethane resin, epoxy resin, etc. used, it is preferable to use it in combination Solvents with a boiling point of more than 100°C that do not cause aggregation or precipitation, or from the viewpoint of the dryness of the protective film ink, it is preferable to use a solvent with a boiling point of 100°C or less in combination.

The above-mentioned protective film ink is preferably formulated such that (C) the solvent content is 95.0% by mass or more and 99.9% by mass or less, the above-mentioned (A) carboxyl-containing transparent polyurethane, (B) epoxy compound and (C) ) Solvent. Furthermore, if necessary, (D) a hardening accelerator may be blended. In the case of blending hardening accelerator (D), after blending, it can be used after mixing until uniform.

The solid content concentration in these protective inks also varies depending on the desired film thickness or printing method, but is preferably 0.1-10% by mass, more preferably 0.5% by mass to 5% by mass. If the solid content concentration is in the range of 0.1-10% by mass, the coating on the transparent conductive film will not cause the shortcomings of no electrical contact due to the excessive thickness of the film, and sufficient weather resistance and light resistance will be obtained. Sexual protective film.

In addition, if halogen is contained in the protective film ink, in the case of a protective film of a transparent conductive film, since the halogen remains in the protective film and adversely affects the conductive part, the lower the halogen content, the better. The amount of halogen contained in the protective film ink is preferably 200 ppm by mass or less, more preferably 100 ppm by mass or less, still more preferably 50 ppm by mass or less, and particularly preferably 10 ppm or less. (B) The epoxy compound is preferably prepared by a method that does not use epichlorohydrin as a synthetic raw material, for example, a compound containing a carbon-carbon double bond is oxidized with a peroxide such as hydrogen peroxide to produce a halogen-free one. Epoxy compound.

Using the above-mentioned protective film ink, the printing pattern is formed on the substrate on which the transparent conductive layer is formed by the printing method such as bar coating printing method, gravure printing method, inkjet method, slit coating method, etc. After the solvent of the printed pattern is dried and removed, it is heated as necessary to harden it into a protective film. By forming the protective film on the transparent conductive layer formed on the transparent substrate, the sheet resistance and haze change after light irradiation are less, and the transparent conductive film with the transparent conductive layer provided with the protective film can be obtained. The term "transparent" in this manual means that the total light transmittance is 75% or more.

In addition, when the protective film ink is cured by heating, it is heated under the conditions of a temperature of 100°C or less and a heating time of 10 minutes or less.

The above-mentioned transparent conductive layer can be produced by printing conductive ink on a transparent substrate. Especially when silver nanowires are used as conductive inks to make a transparent conductive layer, since the surface area per unit mass of silver nanowires is large, and the fine wiring is equivalent to low insulation reliability under high temperature and high humidity, the protective film of the above embodiment The ink protection is effective.

Next, the transparent conductive film that can be provided with the above-mentioned protective film will be described. The transparent conductive film includes a transparent substrate and a transparent conductive layer provided on at least one principal surface of the transparent substrate, and the above-mentioned protective film on the surface of the transparent conductive layer opposite to the transparent substrate. The transparent conductive film can also be coated with a peeling (separable) film with protective function on one or both sides.

＜Transparent substrate＞ The transparent substrate preferably has a total light transmittance of 80% or more. For example, polyester (polyethylene terephthalate [PET], polyethylene naphthalate [PEN], etc.), polycarbonate, acrylic resin (polymethyl methacrylate [PMMA], etc.) can be suitably used. , Resin film of cycloolefin polymer, etc. In addition, these transparent substrates can also have single or plural functions such as easy bonding, optical adjustment (anti-glare, anti-reflection, etc.), hard coating, etc., without compromising optical properties, electrical properties, or bending resistance. The layer can also be provided on one or both sides. Among these resin films, polyethylene terephthalate and cycloolefin polymers are preferably used in terms of excellent light transmittance (transparency), flexibility, and mechanical properties. As the cycloolefin polymer, a hydrogenated ring-opening metallocene polymerized cycloolefin polymer of norbornene (ZEONOR (registered trademark, manufactured by ZEON Co., Ltd.), ZEONEX (registered trademark, manufactured by ZEON Co., Ltd.), ARTON can be used (Registered trademark, manufactured by JSR Co., Ltd.), etc.) or norbornene/ethylene addition copolymerized cycloolefin polymer (APEL (registered trademark, manufactured by Mitsui Chemicals Co., Ltd.), TOPAS (registered trademark, manufactured by POLYPLASTIC Co., Ltd.) )). Those with a mid-glass transition temperature (Tg) of 90 to 170°C are preferred because they can withstand heating in subsequent steps such as pulling out the wiring or the connector part, and more preferably 125 to 145°C. The thickness is preferably 1 to 200 μm, more preferably 5 to 150 μm, and still more preferably 8 to 100 μm.

＜Transparent conductive layer＞ As the conductive fibers constituting the transparent conductive layer, metal nanowires, carbon fibers, etc. are exemplified, and metal nanowires can be suitably used. The metal nanowire is a metal whose diameter is the nanometer level and is a conductive material with a linear shape. In addition, in this embodiment, a porous or non-porous metal nanotube with a tubular shape conductive material can also be used together (mixed) with or instead of the metal nanowire. In this manual, "linear" and "tubular" are both linear, but the former means that the center is not hollow, and the latter means that the center is hollow. The shape can be soft or rigid. The former is called "metal nanowires in a narrow sense", and the latter is called "metal nanotubes in a narrow sense". In the following description, "metal nanowires" include narrowly defined metal nanowires and narrowly defined metal nanotubes. Use it regardless of its meaning. Narrow metal nanowires and narrow metal nanotubes can be used alone or in combination.

As a method of manufacturing metal nanowires, conventional manufacturing methods can be used. For example, silver nanowires can be synthesized by polyol (Poly-ol) method by reducing silver nitrate in the presence of polyvinylpyrrolidone (refer to Chem. Mater., 2002, 14, 4736). The same is true for gold nanowires, which can be synthesized by reducing chloroauric acid hydrate in the presence of polyvinylpyrrolidone (refer to J. Am. Chem. Soc., 2007, 129, 1733). The large-scale synthesis and purification techniques of silver nanowires and gold nanowires are described in detail in the International Publication No. 2008/073143 and International Publication No. 2008/046058. The gold nanowire with porous structure can be synthesized by reducing the chloroauric acid solution by using silver nanowire as a mold. Here, the silver nanowire used in the mold is dissolved in the solution by the oxidation-reduction reaction with chloroauric acid, and the result can be a gold nanotube with a porous structure (refer to J.Am. Chem. Soc., 2004 , 126, 3892-3901).

The average diameter of the metal nanowire is preferably 1 to 500 nm, more preferably 5 to 200 nm, still more preferably 5 to 100 nm, and particularly preferably 10 to 50 nm. In addition, the average long axis length of the metal nanowire is preferably 1 to 100 μm, more preferably 1 to 80 μm, still more preferably 2 to 70 μm, and particularly preferably 5 to 50 μm. The average diameter and thickness of the metal nanowire and the average long axis length satisfy the above ranges, and the average aspect ratio is preferably greater than 5, more preferably 10 or more, still more preferably 100 or more, particularly preferably 200 or more. Here, the aspect ratio refers to the case where the average diameter of the diameter of the metal nanowire is approximated to b, and the average length of the long axis approximates to a, and the value is calculated as a/b. a and b can be measured using scanning electron microscope (SEM) and optical microscope. Specifically, b (average diameter) can be measured using electric field emission scanning electron microscope JSM-7000F (manufactured by JEOL Co., Ltd.) to measure the size (diameter) of arbitrarily selected 100 silver nanowires, and obtain the arithmetic mean value. . In addition, for the calculation of a (average length), a shape measuring laser microscope VK-X200 (manufactured by Keyence Co., Ltd.) can be used to measure the size (length) of 100 silver nanowires arbitrarily selected, and obtain the arithmetic average.

Examples of materials for these metal nanowires include at least one selected from the group consisting of gold, silver, platinum, copper, nickel, iron, cobalt, zinc, ruthenium, rhodium, palladium, cadmium, osmium, and indium, and Alloys formed by combining these metals, etc. In order to obtain a coating film with low surface resistance and high total light transmittance, it is preferable to include at least one of gold, silver, and copper. Due to the high conductivity of these metals, when a certain surface resistance is obtained, the metal density occupied on the surface can be reduced, so a high total light transmittance can be achieved. Among these metals, it is more preferable to include at least one of gold or silver. As the most suitable aspect, for example, silver nanowires.

The transparent conductive layer contains conductive fibers and binder resin. As the binder resin, if it has the bending resistance and transparency that is the subject of the present invention, it can be used without particular limitation. However, the use of metal nanowires using the polyol method as the conductive fiber is based on its production From the viewpoint of solvent (polyol) compatibility, it is preferable to use a binder resin that is soluble in alcohol, water, or a mixed solvent of alcohol and water. Specifically, water-soluble cellulose resins such as poly-N-vinylpyrrolidone, methyl cellulose, hydroxyethyl cellulose, and carboxymethyl cellulose, butyral resin, and poly-N-vinyl can be used. Acetamide (PNVA (registered trademark)). Poly-N-vinylacetamide is a homopolymer of N-vinylacetamide (NVA), but copolymers with N-vinylacetamide (NVA) of more than 70 mol% can also be used. Examples of monomers copolymerizable with NVA are, for example, N-vinylformamide, N-vinylpyrrolidone, acrylic acid, methacrylic acid, sodium acrylate, sodium methacrylate, acrylamide, acrylonitrile, and the like. If the content of the copolymerization component increases, the sheet resistance of the obtained transparent conductive film will increase, and the adhesion between the silver nanowire and the substrate will tend to decrease, and the heat resistance (the temperature at which thermal decomposition begins) will decrease. Therefore, the monomer unit derived from N-vinylacetamide preferably contains more than 70 mol% in the polymer, more preferably contains more than 80 mol%, and still more preferably contains more than 90 mol%. The absolute molecular weight of these polymers is preferably 30,000 to 4 million in terms of weight average molecular weight, more preferably 100,000 to 3 million, and still more preferably 300,000 to 1.5 million. The absolute molecular weight is measured by the following method.

<Measurement of absolute molecular weight> The binder resin was dissolved in the following eluent and left to stand for 20 hours. The binder resin concentration in the solution was 0.05% by mass. This was filtered with a 0.45 μm membrane filter, and the filtrate was measured with GPC-MALS. GPC: Shodex (registered trademark) SYSTEM 21 manufactured by Showa Denko Co., Ltd. Column: TSKgel (registered trademark) G6000PW manufactured by TOSOH Co., Ltd. Column temperature: 40° C. Eluent: 0.1 mol/L, NaH ₂ PO ₄ aqueous solution + 0.1 mol/L Na ₂ HPO ₄ Aqueous solution flow rate: 0.64mL/min Sample injection volume: 100μL MALS detector: Wyatt Technology Corporation, DAWN (registered trademark) DSP Laser wavelength: 633nm Multi-angle nesting method: Berry method

The above-mentioned resins may be used alone or in combination of two or more kinds. In the case of combining two or more types, it is sufficient to simply mix them, and copolymers may also be used.

The transparent conductive layer is formed by printing a conductive ink containing the conductive fiber, a binder resin, and a solvent on at least one main surface of a transparent substrate, and drying to remove the solvent.

As the solvent, if the conductive fiber shows good dispersibility and dissolves the binder resin, it is not particularly limited. However, in the case of using a metal nanowire synthesized by the polyol method as the conductive fiber, it is based on its production From the viewpoint of the compatibility of the solvent (polyol method), alcohol, water, or a mixed solvent of alcohol and water is preferred. As the aforementioned binder resin, it is also preferable to use a binder resin that is soluble in alcohol, water, or a mixed solvent of alcohol and water. From the viewpoint that the drying speed of the adhesive resin can be easily controlled, it is better to use a mixed solvent of alcohol and water. The alcohol contains at least one saturated monovalent alcohol (methanol, ethanol, n-propanol and isopropanol) with carbon atoms of 1 to 3 represented _{by C n} H _{2n+1 OH (n is an integer of 1 to 3)} [Hereinafter simply referred to as "saturated monovalent alcohols with 1 to 3 carbon atoms"]. Saturated monovalent alcohols with 1 to 3 carbon atoms preferably contain more than 40% by mass in all alcohols. If a saturated monovalent alcohol with a carbon number of 1 to 3 is used, the procedure is more convenient because the drying becomes easier. As the alcohol, it can be used in combination with alcohols other than saturated monovalent alcohols having 1 to 3 carbon atoms. Examples of alcohols other than saturated monovalent alcohols having 1 to 3 carbon atoms that can be used in combination include ethylene glycol, propylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, and propylene glycol monoethyl ether. . By combining with the above saturated monovalent alcohols with 1 to 3 carbon atoms, the drying speed can be adjusted. In addition, the total alcohol content in the mixed solvent is preferably 5 to 90% by mass. When the alcohol content in the mixed solvent is less than 5 mass% or more than 90 mass%, the defect of streaks (coating spots) may occur during coating.

The conductive ink can be manufactured by stirring and mixing the binder resin, conductive fiber, and solvent with a rotation revolution mixer or the like. The content of the binder resin contained in the conductive ink is preferably in the range of 0.01 to 1.0% by mass. The content of the conductive fiber contained in the conductive ink is preferably in the range of 0.01 to 1.0% by mass. As a compounding ratio (mass ratio) of the conductive fiber and the binder resin, the binder resin is preferably 0.1-10 relative to the conductive fiber. The content of the solvent contained in the conductive ink is preferably in the range of 98.0 to 99.98% by mass.

In addition, when the aforementioned protective film ink also contains halogen in the conductive ink, when the conductive layer of the transparent conductive film is formed, since the halogen remains in the conductive film and adversely affects the conductive part, the halogen content is preferably lower.

The conductive ink can be printed by printing methods such as bar coating, spin coating, spray coating, gravure, and slit coating. The shape of the printed film or pattern formed at this time is not particularly limited, but examples include the shape of wiring and electrode pattern formed on the substrate, or a film covering the entire or partial surface of the substrate (full-surface pattern) Shape etc. The formed pattern can be made conductive by drying the solvent by heating. The preferred thickness of the transparent conductive layer or transparent conductive pattern obtained after the solvent is dried depends on the diameter of the conductive fiber used or the desired surface resistance value, but it can be 10~300 nm, more preferably 30~200nm . If it is thicker than 10 nm, the number of intersections of the conductive fibers increases and therefore good conductivity is shown. And if it is thinner than 300nm, since light is easily transmitted and reflection due to conductive fibers is suppressed, it exhibits good optical properties. The formed transparent conductive layer or transparent conductive pattern can be made conductive by heating the solvent to dry, but the transparent conductive layer or transparent conductive pattern can also be appropriately irradiated with light as needed. [Example]

Hereinafter, embodiments of the present invention will be described in detail. In addition, the following embodiments are for easy understanding of the present inventor, and the present invention is not limited to these embodiments.

<(A) Synthesis example of carboxyl-containing transparent polyurethane> Synthesis example 1. In a 2L three-necked flask equipped with a stirring device, a thermometer, and a condenser, C-1015N (manufactured by KURARAY Co., Ltd., polycarbonate diol as the (a2) polyol compound, with 1,9- Nonanediol and 2-methyl-1,8-octanediol, molecular weight 1000 (catalog value)) 23.23g, as (a3) 2,2-dimethylolbutanoic acid (DMBA) as a dihydroxy compound containing carboxyl group ) (Manufactured by Huzhou Changsheng Chemical Co., Ltd.) 15 g and 86.8 g of propylene glycol monomethyl ether acetate (PMA (SP value: 8.73)) as a solvent, and dissolve the aforementioned 2,2-dimethylolbutanoic acid at 90°C .

After visually confirming that it has been dissolved, use a dropping funnel to drop DESMODUR (registered trademark)-W ((bis-(4-isocyanatocyclohexyl)methane), Sumika) as a polyisocyanate compound (a1) in 30 minutes. Covestro Urethane Co., Ltd.) 32.78g. After the dropwise addition, the temperature was raised to 100°C, and the reaction was performed at 100°C for 7 hours. After confirming that the isocyanate group had almost disappeared by IR, 0.5 g of isobutanol was added, and the reaction was further performed at 100°C for 2 hours.

Add 45.1 g of PMA as a solvent so that the solid content concentration becomes 35% by mass, and stir until uniform. The weight average molecular weight of the obtained (A) carboxyl-containing transparent polyurethane was 32,300.

Synthesis example 2~13. Except that the raw materials shown in Table 1 were used, (A) a carboxyl group-containing transparent polyurethane was synthesized in the same manner as in Synthesis Example 1. The main skeleton and molecular weight of (a2) polyol compounds other than C-1015N used in Synthesis Example 1 in the table are as follows. UC-100: Polyalkylene carbonate diol, molecular weight 1000 (catalog value) (manufactured by Ube Industries Co., Ltd.) PH-50: Polyalkylene carbonate diol, molecular weight 500 (catalog value) (manufactured by Ube Industries Co., Ltd.) G3450J: Polyalkylene carbonate diol, molecular weight 800 (catalog value) (manufactured by Asahi Kasei Chemical Co., Ltd.) T5651: Polyalkylene carbonate diol, molecular weight 1000 (catalog value) (manufactured by Asahi Kasei Chemical Co., Ltd.)

Synthesis examples 14~23 The synthesis was carried out in the same manner except that the solvent of Synthesis Example 1 was changed as shown in Table 2. In the case of a solvent with a boiling point of 100°C or less, the reaction temperature is 5°C lower than the boiling point.

The abbreviations in the table are shown below. In addition, NPAc is manufactured by Showa Denko Co., Ltd., but other solvents are purchased from Fujifilm Wako Pure Chemical Industries, Ltd. PGDM: Propylene glycol dimethyl ether (SP value: 7.52) DEGDM: Diethylene glycol dimethyl ether (SP value: 8.1) CPME: Cyclopentyl methyl ether (SP value: 8.13) MTHP: 4-methyltetrahydropyran (SP value: 8.13) TEGDM: Triethylene glycol dimethyl ether (SP value: 8.37) NPAc: n-propyl acetate (SP value: 8.72) BCA: Diethylene glycol monobutyl ether acetate (SP value: 8.94) ECA: Diethylene glycol monoethyl ether acetate (SP value: 9.01) BDDA: 1,4-butanediol diacetate (SP value: 9.64) NMP: N-methylpyrrolidone (SP value: 11.52)

＜Visual inspection＞ Table 1 and Table 2 show the visual appearance of each polyurethane solution obtained in Synthesis Examples 1-23. In the synthesis examples 1 to 8 in Table 1, it can be seen that only the conditions of polyol, polyisocyanate, dicarboxylic acid, acid value, etc. are changed, and the appearance of the obtained resin does not change. In Synthesis Examples 1, 2, 3, 5, 8 and Synthesis Examples 9 to 13, it can be seen that only the solvents at the time of synthesis were changed, but there was coloring.

In addition, from Table 2, it can be seen that even if the obtained resin skeleton is the same, only the solvent is changed, and the appearance has a significant change.

From these results, it can be seen that the solvent used in the synthesis greatly affects the coloring, which is not due to the specific resin structure in the scope of the discussion. Regarding the white turbidity or milky white, it is caused by the compatibility of resins with each other. Since the film in the final shape becomes transparent, there is no problem. When the protective film ink composition is made, it is eliminated by adding a good solvent. It is cloudy, so there is no problem.

＜Evaluation of optical properties＞ Example 1 To 10 g of the polyurethane resin solution with a solid content concentration of 35% by mass obtained in Synthesis Example 14, 10 g of 1-hexanol (manufactured by Toyo Gosei Chemical Industry Co., Ltd.) was added, and the mixture was stirred for 3 hours with a stirring shaker manufactured by AS ONE. Let the solid content concentration be 17.5% by mass. Then, using a film coater with a micrometer (manufactured by TAKUMI Giken Co., Ltd.), the untreated COP film (ZF14-100 manufactured by ZEON Co., Ltd., thickness 100μm) was coated with a wet film thickness of 300μm. , Dry at 100°C for 30 minutes. The transparent polyurethane film obtained on the COP film was peeled from the COP, and the film thickness measured with a micrometer was 50 μm. Using this film, a test piece with a size of 3 cm×3 cm was cut out in accordance with the color measurement method of JIS Z8722, and the color and color difference (b* value) was measured using a color difference meter COH7700 manufactured by Nippon Denshoku Kogyo Co., Ltd., and the light source as D65.

Examples 2-10, Comparative Examples 1, 2 The measurement was performed in the same manner as in Example 1, except that the polyurethane resin solution obtained by each synthesis example shown in Table 3 was used. The results are shown in Table 3.

It can be seen from Table 3 that Examples 1 to 10 are suitable for obtaining optical properties, especially a colorless and transparent film with a b* value of 0.25 or less.

＜Thermosetting composition for protective film＞ Modulation example 1 Add 10 g of the 35% by mass polyurethane resin solution obtained as (A) Synthesis Example 14 of carboxyl group-containing transparent polyurethane, and (B) pentaerythritol tetraglycidyl ether as epoxy resin (Showa Denko Co., Ltd.) 0.49g, (D) U-CAT (registered trademark) 5003 as a hardening accelerator 0.24g, (C) 1-hexanol as a solvent 65.19g, ethyl acetate (Fuji Film Wako Pure Chemical Industries, Ltd.) Company make) 65.19g, stirred with a stirring shaker for 2 hours to make it uniform. The halogen content of the obtained protective film ink is 10 mass ppm or less. The content of halogen atoms is the value measured in accordance with JIS K7243-3.

Modification example 2~12 The composition was produced in the same manner as in Preparation Example 1, except that the polyurethane resin solutions were replaced with those shown in Table 4, respectively.

Modification examples 13, 14 The composition was produced in the same manner as in Preparation Example 1, except that the polyurethane resin solutions were replaced with those shown in Table 4, and the curing accelerator was replaced with U-CAT (registered trademark) SA102 (manufactured by SAN APRO Co., Ltd.).

Modulation example 15 The composition was produced in the same manner as in Preparation Example 1, except that the polyurethane resin solutions were replaced with those shown in Table 4 and the hardening accelerator was not used.

<Transparent conductive film><Production of silver nanowire> Polyvinylpyrrolidone K-90 (manufactured by Nippon Shokubai Co., Ltd.) (0.98g), AgNO ₃ (1.04g) and FeCl ₃ (0.8mg) are dissolved In ethylene glycol (250ml), the reaction was heated at 150°C for 1 hour. The obtained silver nanowire coarse dispersion was dispersed in 2000 ml of methanol, and poured into a desktop small tester (manufactured by Nippon Kenko Co., Ltd., using a ceramic membrane filter CEFILT, with a membrane area of 0.24 m ² , a pore size of 2.0 μm, and a size of ϕ 30 mm× 250mm, filtration differential pressure 0.01MPa), circulating flow rate 12L/min, dispersion temperature 25℃, cross flow filtration (cross flow filtration) to remove impurities, concentrated to the total amount of 100g, to obtain silver nanowires (average diameter : 26nm, average length: 20μm) methanol dispersion. The average diameter of the obtained silver nanowires was calculated by using an electric field emission scanning microscope JSM-7000F (manufactured by JEOL Co., Ltd.) to measure the size of 100 silver nanowires arbitrarily selected, and calculate the arithmetic average. In addition, the average length of the obtained silver nanowires was calculated by using a shape measuring laser microscope VK-X200 (manufactured by Kenyence Co., Ltd.) to measure the size of 100 silver nanowires arbitrarily selected, and obtain the arithmetic average. In addition, the above-mentioned methanol, ethylene glycol, AgNO ₃ , and FeCl ₃ use Fujifilm Wako Pure Chemical Co., Ltd. reagents.

＜Production of conductive ink (silver nanowire ink)＞ 11g of methanol dispersion of silver nanowire synthesized by the above polyol method (silver nanowire concentration 0.62% by mass), 3.5g water, 10.8g ethanol (manufactured by Fujifilm Wako Pure Chemical Co., Ltd.), propylene glycol monomethyl Ether (PGME, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) 12.8 g, propylene glycol 1.2 g (PG, manufactured by Asahi Glass Co., Ltd.), PNVA (registered trademark) aqueous solution (manufactured by Showa Denko Co., Ltd., solid content concentration 10 mass %, weight average molecular weight 900,000) 0.7g, mixed with a stirring shaker VMR-5R (manufactured by AS ONE Co., Ltd.) at room temperature and atmospheric environment for 1 hour (rotation speed 100 rpm) to produce silver nanowire ink 40g.

＜Formation of transparent conductive layer (silver nanowire layer)＞ Plasma treatment was performed using a plasma treatment device (AP-T03 manufactured by Sekisui Chemical Industry Co., Ltd.) (gas: nitrogen, conveying speed: 50mm/sec, treatment time: 6 seconds, setting voltage: 400V), and used as a transparent substrate On the A4 size cycloolefin polymer film ZF14-050 (50μm thick by ZEON Co., Ltd., Japan), TQC automatic film coater standard (manufactured by COTEC Co., Ltd.) and wireless bar coater OSP-CN- 22L (manufactured by COTEC Co., Ltd.), the transparent substrate (ZF14-050) is coated with silver nanowire ink (coating speed 500mm/sec) so that the wet film thickness becomes 22μm. Subsequently, it was dried with a thermostat HISPEC HS350 (manufactured by Kusumoto Chemical Co., Ltd.) under hot air at 80°C for 1 minute in an atmospheric environment to form a silver nanowire layer (film thickness after drying: 90 nm). The film thickness was measured using a film thickness measurement system F20-UV (manufactured by FILMETRICS Co., Ltd.) based on the optical interference method. Change the measurement position, and use the average value of 3 points as the film thickness. The analysis system uses a spectrum of 450nm to 800nm. According to this measuring system, the film thickness (Tc) of the silver nanowire ink coating (transparent conductive layer) formed on the transparent substrate (ZF14-050) can be directly measured.

＜Formation of protective film (production of transparent conductive film)＞ Example 11 On the silver nanowire layer formed on a transparent substrate, using the TQC automatic film coater standard (manufactured by COTEC Co., Ltd.), using the wireless rod coater OSP-CN-10M, the wet film thickness becomes 5μm In this way, the thermosetting composition for protective film of Preparation Example 1 shown in Table 4 was applied. Subsequently, it was dried (thermally cured) with a thermostat HISPEC HS350 (manufactured by Kusumoto Chemical Co., Ltd.) at 80° C. in an atmospheric environment with hot air for 1 minute to form a protective film (film thickness after drying: 90 nm). The film thickness of the protective film was measured using the film thickness measurement system F20-UV (manufactured by FILMETRICS Co., Ltd.) based on the light interference method in the same way as the film thickness of the silver nanowire ink coating film described above. Change the measurement position, and use the average value of 3 points as the film thickness. The analysis system uses a spectrum of 450nm to 800nm. According to this measuring system, it is possible to directly measure the total film thickness (Tc) of the silver nanowire ink coating film (transparent conductive layer) formed on the transparent substrate and the film thickness (Tp) of the protective film formed thereon. Thickness (Tc+Tp), so the protective film thickness (Tp) is obtained by subtracting the previously measured film thickness (Tc) of the silver nanowire ink coating (transparent conductive layer) from the measured value.

Examples 12-23, Comparative Examples 3 and 4 A transparent conductive film was produced in the same manner as in Example 11 except that the protective film compositions were replaced with those shown in Table 4, respectively.

＜Measurement of surface resistance＞ Cut a 3cm×3cm test piece from the above-mentioned A4 size fully coated silver nanowire coating film, and touch the terminal of the manual non-destructive resistance tester EC-80P (manufactured by NAPSON Co., Ltd.) to the center of the test piece Department of measurement. Either film showed a sheet resistance value of about 40Ω/□.

<Total light transmittance, turbidity measurement, color measurement (b*)> Use the above 3cm×3cm test piece, according to JIS Z8722 color measurement method, JIS K7361-1 transparent material total light transmittance measurement method, JIS K7136 transparent material haze determination method, use color difference meter COH7700( (Manufactured by Nippon Denshoku Industries Co., Ltd.), the light source was set to D65, and the total light transmittance, turbidity, and color difference (b* value) were measured. The measurement results are summarized in Table 4.

It can be seen from Table 4 that the transparent conductive film with protective film prepared by using a resin synthesized with a solvent with an SP value of 9.80 or more produces rainbow spots or haze, and the b* value exceeds 1.00. Especially in the case of using NMP with an SP value exceeding 10, the haze is also a value exceeding 2.0, which shows that it is not suitable for a transparent conductive film. In contrast, in the case of using solvents with SP values below 9.80 in Examples 11 to 23 to synthesize protective film resins, the turbidity is below 2.0, and the b* value below 1.00 indicates that it is suitable for transparent conductive films.

Claims (14)

A (A) carboxyl group-containing transparent polyurethane, characterized in that the b* value when the film is formed to a thickness of 50 μm is 0.25 or less. Such as claim 1 (A) carboxyl group-containing transparent polyurethane, wherein the aforementioned (A) carboxyl group-containing transparent polyurethane uses (a1) a polyisocyanate compound, (a2) a polyol compound, and (a3) A carboxyl-containing dihydroxy compound synthesized as a monomer. According to claim 2 (A) carboxyl group-containing transparent polyurethane, wherein the aforementioned (a2) polyol compound is a polycarbonate polyol. According to claim 2 or 3, (A) carboxyl group-containing transparent polyurethane, wherein the aforementioned (a1) polyisocyanate compound is an aliphatic polyisocyanate or an alicyclic polyisocyanate. A thermosetting composition comprising (A) a carboxyl group-containing transparent polyurethane with a b* value of 0.25 or less when the film is formed to a thickness of 50 μm, (B) an epoxy compound, and (C) a solvent. The thermosetting composition according to claim 5, which further contains (D) a hardening accelerator. The thermosetting composition according to claim 5 or 6, wherein the aforementioned (B) epoxy compound is a multifunctional epoxy compound having 3 or more epoxy groups in one molecule. A transparent conductive film, which has a transparent substrate, a transparent conductive layer arranged on at least one surface of the transparent substrate, and a protective film arranged on the surface of the transparent conductive layer opposite to the transparent substrate. The characteristic is The aforementioned protective film is a cured film of a thermosetting composition comprising (A) carboxyl-containing transparent polyurethane, (B ) Epoxy compound and (C) solvent. The transparent conductive film of claim 8, wherein the transparent conductive layer includes metal nanowires. Such as the transparent conductive film of claim 9, wherein the aforementioned metal nanowire is a silver nanowire. A manufacturing method of (A) carboxyl-containing transparent polyurethane as in any one of claims 1 to 4, which is characterized by using a solvent with an SP value of less than 9.80 by Fedors’s calculation as the synthesis solvent . The method for producing transparent polyurethane according to claim 11, wherein the aforementioned solvent is selected from the group consisting of diethanol monobutyl ether acetate, 1,4-butanediol diacetate, tripropylene glycol dimethyl ether, and propylene glycol Dimethyl ether, diethylene glycol dibutyl ether, triethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, tripropylene glycol dimethyl ether, n-propyl acetate, n-butyl acetate, 1,4-dioxane, Any of the group consisting of methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, isophorone, tetrahydrofuran, 4-methyltetrahydropyran, and cyclopentyl methyl ether. According to claim 11, the method for producing transparent polyurethane, wherein the aforementioned solvent is 4-methyltetrahydropyran or triethylene glycol dimethyl ether. According to claim 11, the method for producing transparent polyurethane, wherein the aforementioned solvent is methyltetrahydropyran.