JP2010072448A - Adhesive for liquid crystal film, liquid crystal film, and optical element film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive capable of restraining a tightening force between respective layers in a liquid crystal film from being changed with the lapse of time, and to provide the liquid crystal film or an optical element film using the adhesive. <P>SOLUTION: This adhesive with environmental stability for the liquid crystal film contains 1 to 50 mass% of acryl amide monomer in total component amount of the adhesive. The liquid crystal film or the optical element film is a film for compensating a visibility angle or the like, comprising a liquid crystal substance alignment-immobilized on an alignment substrate. The film is transferred to another substrate by the adhesive, the alignment substrate is separated, the film is thinned and weight-lightened, and the tightening force is restrained from being changed with the lapse of time, by using the adhesive. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an adhesive for a liquid crystal film useful for transferring or laminating a liquid crystal substance layer, a liquid crystal film obtained using the adhesive, and an optical element film using the same.

In recent years, higher durability is required for liquid crystal films used in liquid crystal display devices in addition to excellent optical performance. In particular, liquid crystal display devices for mobile devices such as mobile phones and in-vehicle devices are required to pass strict environmental tests assuming various use conditions.
Thin films (films) consisting of alignment layers of liquid crystal compounds, especially films made of liquid crystal materials with a fixed nematic structure, twisted nematic structure, or nematic hybrid structure, are used for wave plates for liquid crystal display elements, for color compensation and viewing angle compensation. And has excellent performance as an optical rotatory optical element, etc., and contributes to high performance and light weight of various display elements. As a method for producing these films, a method of transferring a layer made of a liquid crystal material formed on an alignment substrate onto a light-transmitting substrate that also serves as a support substrate has been proposed (Patent Documents 1 to 3).

Furthermore, as a measure to endure the severe durability test required for liquid crystal display elements, and for further reduction in thickness and weight, the manufacture of optical elements composed of liquid crystal material layers that do not use a support substrate film A method has also been proposed (Patent Documents 4 to 6). According to this manufacturing method, the layer made of the liquid crystal material formed on the alignment substrate is temporarily transferred to the temporary substrate via an adhesive, and then the temporary substrate is peeled off, so that there is no support substrate film. An optical element made of a liquid crystal material layer can be manufactured.
However, with conventional adhesives, the adhesive strength between the support substrate and the adhesive layer and between the liquid crystal substance layer and the adhesive layer may deteriorate with time, and may peel off during use. In addition, the adhesive force between the support substrate and the temporary substrate and the adhesive layer decreases with the lapse of time, which may cause a manufacturing trouble during the optical element manufacturing process.

JP-A-4-57017 JP-A-4-177216 JP-A-6-242434 JP-A-8-278491 JP 2004-117422 A JP 2004-138697 A

  The object of the present invention is to solve the above-mentioned problem and to change the adhesion force between layers without causing a decrease in the adhesion force between the substrate different from the alignment substrate used for the alignment of the liquid crystal material and the liquid crystal material layer over time. An adhesive capable of being suppressed is provided, and a liquid crystal film and an optical element film using the adhesive are provided.

The present inventors have found a specific adhesive for liquid crystal film, found that the above-mentioned problems can be solved by using the adhesive, and have completed the present invention.
That is, the present invention is as follows.

[1] An adhesive for a liquid crystal film, comprising 1% by mass to 50% by mass of an acrylamide monomer in the adhesive.
[2] A liquid crystal film obtained by adhering at least a liquid crystal material layer having an alignment on an alignment substrate fixed to the substrate different from the alignment substrate with the adhesive for a liquid crystal film according to the above [1], and peeling the alignment substrate.
[3] The above-mentioned liquid crystal material layer in which the alignment is fixed is composed of a polymer liquid crystal material that aligns liquid crystal at a temperature equal to or higher than the liquid crystal transition point and enters a glass state at a temperature equal to or lower than the liquid crystal transition point. 2] Liquid crystal film.
[4] The liquid crystal film according to the above [2], wherein the liquid crystal material layer in which the alignment is fixed is obtained by crosslinking a liquid crystal material layer in which low-molecular liquid crystals or polymer liquid crystals are aligned.
[5] An optical element film using the liquid crystal film according to any one of [2] to [4].

  By using the liquid crystal film adhesive of the present invention, it is possible to suppress a change (decrease) in the adhesion force between the substrate different from the alignment substrate used for the alignment of the liquid crystal material and the liquid crystal material layer over time, and various severe conditions. It is possible to provide a liquid crystal film and an optical element film that are compatible with environmental tests.

Hereinafter, the present invention will be described in detail.
The adhesive for liquid crystal films of the present invention is an adhesive for liquid crystal films, wherein the acrylamide monomer is 1% by mass to 50% by mass of the total amount of adhesive components.
The acrylamide monomer in the present invention is, for example, an active form (acid chloride, mixed acid anhydride, active ester, etc.) of acrylic acid or methacrylic acid (hereinafter collectively referred to as “(meth) acrylic acid”) and an amine. A compound synthesized by the reaction with. Examples of these compounds include (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, (meth) acryloylmorpholine, N-isopropyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, diacetone (meth) acrylamide, etc. can be mentioned.
Among these compounds, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, and (meth) acryloylmorpholine are particularly preferable.

  Further, for the purpose of balancing the hydrophilicity / lipophilicity of the adhesive for liquid crystal films, a compound obtained by modifying an acrylamide monomer with ethylene oxide or propylene oxide may be used instead of the acrylamide monomer.

  The content of the acrylamide monomer in the adhesive for a liquid crystal film of the present invention is 1% by mass to 50% by mass, preferably 1% by mass to 40% by mass, based on the total amount of the adhesive components. If the content is too small, the effect may not be recognized. If the content is too large, the adhesive strength with the liquid crystal substance layer may be lowered, which is not desirable.

  Components other than the acrylamide-based monomer constituting the adhesive of the present invention are not particularly limited, and known adhesives can be used. For example, (meth) acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyvinyl ether, vinyl acetate / vinyl chloride copolymer, modified polyolefin, epoxy, fluorine, natural rubber, synthetic rubber, etc. What uses a polymer as a base polymer can be selected suitably, and can be used. These are more preferably energy ray reactive types such as ultraviolet rays and electron beams, and are particularly excellent in optical transparency, such as acrylic adhesives mainly composed of (meth) acryloyl groups, and have appropriate wettability, cohesiveness and adhesion. Those exhibiting characteristics and excellent in weather resistance, heat resistance and the like are preferably used.

  The adhesive of the present invention can contain other components as necessary. For example, various (meth) acrylic monomers, (meth) acrylic oligomers, or photopolymerization initiators, cationic polymerization initiators, surface modifiers, viscosity modifiers, tackifiers, antiblocking agents, antioxidants Various additives such as an agent, an antistatic agent, a heat stabilizer, and an impact resistance improver can be mentioned.

  Examples of the (meth) acrylic monomer include ethyl (meth) acrylate, butyl (meth) acrylate, hydroxyethyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, and isobornyl. (Meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, ethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (Meth) acrylate, tris [(2-acryloyloxy) ethyl] isocyanurate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaa Examples include (relate) and dipentaerythritol hexaacrylate. Examples of the (meth) acrylic oligomer include polyester (meth) acrylate, epoxy (meth) acrylate, urethane (meth) acrylate, polyether (meth) acrylate, silicone ( And (meth) acrylate. These may be a mixture. Further, a monomer copolymerizable with a (meth) acryloyl group, for example, N-vinylformamide, N-vinylmorpholine, N-vinylpyrrolidone, styrene or the like may be used in combination. The (meth) acrylic monomer may be modified with ethylene oxide or propylene oxide for the purpose of balancing the hydrophilicity / lipophilicity of the adhesive.

  Examples of the photopolymerization initiator include known photopolymerization initiators such as benzoin alkyl ethers, benzylmethyl ketals, hydroxyphenyl ketones, 1,1-dichloroacetophenone, thioxanthones, hexaarylbiimidazoles, acylphosphine. Examples thereof include benzophenones combined with fin oxides or amines. These may be used as a mixture and, if necessary, a sensitizer may be used in combination. The amount of the photopolymerization initiator used is in the range of 0.1 to 10% by mass, preferably 0.5 to 7% by mass of the adhesive. Outside this range, polymerization is difficult to proceed, and light resistance due to cleaved initiator residue deteriorates.

  The surface modifier is not particularly limited as long as it has good compatibility with the adhesive and does not affect the curability of the adhesive or the optical performance after curing, an ionic or nonionic water-soluble surfactant, Oil-soluble surfactants, polymer surfactants, fluorine-based surfactants, silicone-based surfactants, organometallic surfactants, reactive surfactants, and the like can be used. Of these, fluorine-based surfactants and silicone-based surfactants are preferable because they have a great effect of reducing the peeling force.

The thickness of the adhesive layer is usually 0.5 to 50 μm, desirably 0.5 to 20 μm, and more desirably 1 to 10 μm. If the thickness is less than 0.5 μm, it is difficult to process when peeling from the liquid crystal material layer, and if it is more than 50 μm, it takes time to cure the adhesive layer, and unfavorable peeling failure is likely to occur. .
The adhesive layer is applied in a solution or in a molten state by an appropriate method such as a flexographic printing method, an offset printing method, a dispenser method, a gravure coating method, a micro gravure method, a bar coating method, a screen printing method, a lip coating method, or a die coating method. do it.

  The liquid crystal material layer in which the alignment of the liquid crystal used in the present invention is fixed is a layer fixed by using means for fixing the liquid crystal material in the alignment state. As a means of fixing the alignment of the liquid crystal, in the case of a polymer liquid crystal material, a method of rapidly cooling from the alignment state and fixing in a vitrified state, in the case of a low molecular liquid crystal material having a reactive functional group or a polymer liquid crystal material May be a method in which the functional group is reacted (cured, crosslinked, etc.) and fixed after the orientation.

  Examples of the reactive functional group include a vinyl group, a (meth) acryloyl group, a vinyloxy group, an oxiranyl group, an oxetanyl group, a carboxyl group, a hydroxyl group, an amino group, an isocyanate group, and an acid anhydride group. The reaction is carried out by a method suitable for the above.

  The liquid crystal material that can be used for the liquid crystal material layer can be selected from a wide range regardless of whether it is a low-molecular liquid crystal material or a high-molecular liquid crystal material, depending on the intended use and manufacturing method of the liquid crystal film. Substances are preferred. Furthermore, the molecular shape of the liquid crystal substance may be a rod shape or a disk shape. For example, a discotic liquid crystal compound exhibiting a discotic nematic liquid crystal property can also be used.

  Examples of the liquid crystal phase of the liquid crystal material layer before fixing include a nematic phase, a twisted nematic phase, a cholesteric phase, a smectic phase, a discotic nematic phase, and the like. Examples of the alignment state include a homogeneous alignment that is horizontally aligned on the alignment substrate, a homeotropic alignment that is aligned vertically, and a tilt alignment and a hybrid alignment that are considered to be an intermediate state therebetween.

Low molecular liquid crystal substances include saturated benzene carboxylic acids, unsaturated benzene carboxylic acids, biphenyl carboxylic acids, aromatic oxycarboxylic acids, Schiff base types, bisazomethine compounds, azo compounds, azoxy compounds, cyclohexane ester compounds Examples thereof include a compound exhibiting liquid crystallinity in which the reactive functional group is introduced at the terminal, such as sterol compounds, and a composition obtained by adding a crosslinkable compound to a compound exhibiting liquid crystallinity among the compounds.
Examples of the discotic liquid crystal compound include triphenylene and torquesen.

  As the polymer liquid crystal material, various main chain polymer liquid crystal materials, side chain polymer liquid crystal materials, or a mixture (composition) thereof can be used.

  Main chain polymer liquid crystal materials include polyester, polyamide, polycarbonate, polyimide, polyurethane, polybenzimidazole, polybenzoxazole, polybenzthiazole, polyazomethine, polyesteramide, polyester carbonate Polymer liquid crystal substances such as polyester and polyesterimide, or mixtures thereof. Of these, liquid crystalline polyesters are preferable from the viewpoints of ease of synthesis, orientation, glass transition point, and the like, and the reactive functional groups may be bonded.

The main chain type liquid crystalline polyester includes an aromatic diol unit (hereinafter referred to as a structural unit (A)), an aromatic dicarboxylic acid unit (hereinafter referred to as a structural unit (B)) and an aromatic hydroxycarboxylic acid unit (hereinafter referred to as a structural unit (B)). The main-chain liquid crystalline polyester containing at least two of the structural units (C) as essential units.
Hereinafter, the structural units (A), (B), and (C) will be sequentially described.

  The compound for introducing the structural unit (A) is preferably a compound represented by the following general formula (a), specifically, catechol, resorcin, hydroquinone or the like or a substituted product thereof, 4,4′-biphenol 2,2 ′, 6,6′-tetramethyl-4,4′-biphenol, 2,6-naphthalenediol, and the like, and in particular, catechol, resorcin, hydroquinone, and the like, or substituted products thereof are preferable.

However, -X in the _{formula, -H, -CH 3, -C 2} H 5, -CH 2 CH 2 CH 3, -CH (CH 3) 2, -CH 2 CH 2 CH 2 CH 3, -CH _{2 CH (CH 3) CH 3} , -CH (CH 3) CH 2 CH 3, -C (CH 3) 3, -OCH 3, -OC 2 H 5, -OC 6 H 5, -OCH 2 C 6 H ₅ , —F, —Cl, —Br, —NO ₂ , or —CN, particularly preferably a compound represented by the following formula (a ′).

  As the compound for introducing the structural unit (B), a compound represented by the following general formula (b) is preferable. Specifically, terephthalic acid, isophthalic acid, phthalic acid or the like or a substituted product thereof, 4, 4 Examples include '-stilbene dicarboxylic acid or a substituted product thereof, 2,6-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, and the like, and terephthalic acid, isophthalic acid, phthalic acid, and the like or substituted products thereof are particularly preferable.

However, -X in the _{formula, -H, -CH 3, -C 2} H 5, -CH 2 CH 2 CH 3, -CH (CH 3) 2, -CH 2 CH 2 CH 2 CH 3, -CH _{2 CH (CH 3) CH 3} , -CH (CH 3) CH 2 CH 3, -C (CH 3) 3, -OCH 3, -OC 2 H 5, -OC 6 H 5, -OCH 2 C 6 H ₅ , -F, -Cl, -Br, -NO ₂ , or -CN.

  As the compound for introducing the structural unit (C), a compound represented by the following general formula (c) is preferable, and specifically, hydroxybenzoic acid or a substituted product thereof, 4′-hydroxy-4-biphenylcarboxylic acid Or a substituted product thereof, 4′-hydroxy-4-stilbenecarboxylic acid or a substituted product thereof, 6-hydroxy-2-naphthoic acid, 4-hydroxycinnamic acid, and the like. Particularly, hydroxybenzoic acid and a substituted product thereof, 4 '-Hydroxy-4-biphenylcarboxylic acid or a substituted product thereof, 4'-hydroxy-4-stilbenecarboxylic acid or a substituted product thereof is preferred.

However, -X in the formula, -X _1, -X ₂ are each _{individually, -H, -CH 3, -C 2} H 5, -CH 2 CH 2 CH 3, -CH (CH 3) 2, _{-CH 2 CH 2 CH 2 CH 3} , -CH 2 CH (CH 3) CH 3, -CH (CH 3) CH 2 CH 3, -C (CH 3) 3, -OCH 3, -OC 2 H 5, -OC ₆ H _5, represents _{-OCH 2 C 6 H 5, -F} , -Cl, -Br, any group of -NO _2, or -CN,.

  The main-chain liquid crystalline polyester contains at least two kinds of (A) an aromatic diol unit, (B) an aromatic dicarboxylic acid unit, and (C) an aromatic hydroxycarboxylic acid unit as a structural unit. Any other structural unit may be used as long as it exhibits liquid crystallinity, and the other structural units are not particularly limited as long as these conditions are satisfied.

  The proportion of the structural units (A), (B) and (C) constituting the main chain type liquid crystalline polyester in the total structural units is such that the structural units (A), (B) and (C) are diols or dicarboxylic acids or When expressed as a ratio of the sum of the weights of all the monomers as the hydroxycarboxylic acid, it is usually 20 to 99%, preferably 30 to 95%, particularly preferably 40 to 90%. If it is less than 20%, the temperature range for developing liquid crystallinity may be extremely narrow, and if it exceeds 99%, the liquid crystal phase expression temperature may be too high.

  The main-chain liquid crystalline polyester can contain structural units other than the above (A), (B) and (C). Other structural units that can be contained are not particularly limited, and compounds known in the art (monomer: (D)) can be used. For example, naphthalene carboxylic acid, biphenyl carboxylic acid, aliphatic carboxylic acid and compounds in which a halogen group, alkyl group or alkoxy group is introduced, biphenol, naphthalenediol, aliphatic diol and these compounds in halogen group, alkyl group or The compound etc. which introduce | transduced the alkoxy group can be mentioned.

Further, when an optically active compound is used as a raw material for the units constituting the main chain type liquid crystalline polyester, it is possible to impart a chiral phase to the main chain type liquid crystalline polyester. The optically active compound is not particularly limited. For example, an optically active aliphatic alcohol (C _n H _{2n + 1} OH, where n represents an integer of 4 to 14), an optically active aliphatic group is bonded. alkoxy benzoate _{(C n H 2n + 1 O} -Ph-COOH, where n is 4 to 14 integer, Ph represents a phenylene group.), menthol, camphor acid, naproxen derivatives, binaphthol, 1,2-propanediol, 1 , 3-butanediol, 2-methylbutanediol, 2-chlorobutanediol, tartaric acid, methylsuccinic acid, 3-methyladipic acid and the like.

  The molecular weight of the main-chain liquid crystalline polyester is preferably such that the logarithmic viscosity η measured at 30 ° C. in a phenol / tetrachloroethane mixed solvent (mass ratio 60/40) is 0.03 to 0.50 dl / g. Preferably it is 0.05-0.15 dl / g. When η is smaller than 0.03 dl / g, the solution viscosity of the main-chain liquid crystalline polyester is low, and there is a possibility that a uniform coating film cannot be obtained when forming into a film. On the other hand, when it is larger than 0.50 dl / g, the alignment treatment temperature required for aligning the liquid crystal becomes high, and there is a risk of decreasing the alignment property.

  In the present invention, the molecular weight control of the main chain type liquid crystalline polyester is determined solely by the charged composition. Specifically, by introducing a monofunctional monomer that reacts in such a manner as to seal both ends of the molecule, that is, a structural unit having one hydroxyl group or carboxyl group (such as (D) above), Depending on the content, the average degree of polymerization (average number of bonds of structural units (A) to (D)) of the main-chain liquid crystalline polyester obtained is determined. Therefore, in order to obtain a main-chain liquid crystalline polyester having a desired logarithmic viscosity, it is necessary to adjust the charged composition according to the type of charged monomer.

As a method for synthesizing the main-chain liquid crystalline polyester, a method used when synthesizing a normal polyester can be adopted, and the method is not particularly limited. For example, a method in which a carboxylic acid unit is activated to an acid chloride or a sulfonic acid anhydride and reacted with a phenol unit in the presence of a base (acid chloride method), a carboxylic acid unit and a phenol unit are converted into DCC (dicyclohexylcarbodiimide), etc. A method of directly condensing using a condensing agent of the above, a method of acetylating a phenol unit, and deaceticating polymerization of this with a carboxylic acid unit under melting conditions can be used. The crude main chain type liquid crystalline polyester obtained by the polymerization reaction may be purified by a method such as recrystallization or reprecipitation.
Further, the main chain type liquid crystalline polyester may have the above-mentioned reactive functional group at the terminal.

Examples of the side chain type polymer liquid crystal material include materials having a linear or cyclic skeleton such as polyacrylate, polymethacrylate, polyvinyl, polysiloxane, polyether, polymalonate, and polyester. In addition, a polymer liquid crystal substance in which a mesogen group is bonded as a side chain, or a mixture thereof.
Among these, poly (meth) acrylates bonded with a reactive group represented by the following general formula (1) are preferable.

In Formula (1), each R ³ independently represents hydrogen or a methyl group, and each R ⁴ independently represents hydrogen, methyl group, ethyl group, butyl group, hexyl group, octyl group, nonyl group, decyl group. Group, dodecyl group, methoxy group, ethoxy group, propoxy group, butoxy group, pentyloxy group, hexyloxy group, heptyloxy group, octyloxy group, decyloxy group, dodecyloxy group, cyano group, bromo group, chloro group, fluoro R ⁵ represents a hydrogen group, a methyl group or an ethyl group, R ⁶ represents a hydrocarbon group having 1 to 24 carbon atoms, and L ² each independently represents a group or a carboxyl group. Represents a single bond, —O—, —O—CO—, —CO—O—, —CH═CH— or —C≡C—, p represents an integer of 1 to 10, and q represents Represents an integer of 10 from, a, b, c, d, e and f represent the mole ratio of each unit in the polymer (a + b + c + d + e + f = 1.0, but not the c + d + e = 0).

The molar ratio of each component constituting the side chain type polymer liquid crystal material represented by the formula (1) is not a + b + c + d + e + f = 1.0, c + d + e = 0, and needs to exhibit liquid crystallinity. The molar ratio of each component may be arbitrary as long as this requirement is satisfied, but is preferably as follows.
a: Preferably 0 to 0.80, more preferably 0.05 to 0.50
b: preferably 0 to 0.90, more preferably 0.10 to 0.70
c: preferably 0 to 0.50, more preferably 0.10 to 0.30
d: preferably 0 to 0.50, more preferably 0.10 to 0.30
e: preferably 0 to 0.50, more preferably 0.10 to 0.30
f: Preferably 0 to 0.30, more preferably 0.01 to 0.10

Each component in these poly (meth) acrylates does not need to be present in all six types as long as the above conditions are satisfied.
R ⁴ is preferably hydrogen, methyl group, butyl group, methoxy group, cyano group, bromo group or fluoro group, particularly preferably hydrogen, methoxy group or cyano group, and L ² is preferably Is a single bond, —O—, —O—CO— or —CO—O—, and R ⁶ is preferably a hydrocarbon group having 2, 3, 4, ⁶ , 8, 10 and 18 carbon atoms. To express.
Furthermore, although the birefringence of the side chain type polymer liquid crystal substance represented by the general formula (1) varies depending on the molar ratio of each of the components a to f and the orientation form, the birefringence when the nematic orientation is taken. Is preferably 0.001 to 0.300, more preferably 0.05 to 0.25.

Each (meth) acrylic compound corresponding to each component of the above-mentioned side chain polymer liquid crystal substance can be obtained by an ordinary organic chemistry synthesis method.
A (meth) acrylic compound having an oxetanyl group can be obtained by, for example, combining a site having an oxetanyl group and a site having a (meth) acryloyl group by means such as Williamson's ether synthesis or ester synthesis using a condensing agent. A (meth) acrylate having an oxetanyl group having two reactive groups completely different from an oxetanyl group and a (meth) acryloyl group can be synthesized. However, in the reaction, since the oxetanyl group has cationic polymerizability, it is necessary to select reaction conditions in consideration of causing side reactions such as polymerization and ring opening under strong acidic conditions. May be appropriately selected from the range described in detail in the synthesis of the compound represented by the general formula (2) described later.
Said side chain type polymer liquid crystal substance is easily synthesized by copolymerizing (meth) acrylic group of each (meth) acrylic compound obtained by the above method corresponding to each component by radical polymerization or anionic polymerization. can do. Polymerization conditions are not particularly limited, and normal conditions can be employed.

  As an example of radical polymerization, a (meth) acrylic compound corresponding to each component is dissolved in a solvent such as dimethylformamide (DMF) or diethylene glycol dimethyl ether, and 2,2′-azobisisobutyronitrile (AIBN) or benzoyl peroxide is dissolved. The method of making it react for several hours at 60-120 degreeC by using (BPO) etc. as an initiator is mentioned. Moreover, in order to make the liquid crystal phase appear stably, copper bromide (I) / 2,2′-bipyridyl series, 2,2,6,6-tetramethylpiperidinooxy free radical (TEMPO) series, etc. are used. A method of controlling the molecular weight distribution by conducting living radical polymerization as an initiator is also effective. These radical polymerizations need to be performed under deoxygenated conditions.

  An example of anionic polymerization is a method in which a (meth) acrylic compound corresponding to each component is dissolved in a solvent such as tetrahydrofuran (THF) and reacted with a strong base such as an organic lithium compound, an organic sodium compound, or a Grignard reagent as an initiator. Can be mentioned. In addition, the molecular weight distribution can be controlled by optimizing the initiator and the reaction temperature for living anionic polymerization. These anionic polymerizations need to be performed under dehydration and deoxygenation conditions.

  The side chain type polymer liquid crystal substance preferably has a weight average molecular weight of 1,000 to 200,000, particularly preferably 3,000 to 50,000. Outside this range, the strength is insufficient or the orientation is deteriorated.

  In addition, the above-mentioned discotic liquid crystal molecules, that is, discotic liquid crystal molecules, are described in various documents (C. Destrade et al., Mol. Cryst. Liq. Cryst., Vol. 71, page 111 (1981); Chapter, Quarterly Chemistry Review, No. 22, Liquid Crystal Chemistry, Chapter 5, Chapter 10, Section 2 (1994); B. Kohne et al., Angew. Chem. Soc. Chem. Comm., Page 1794 ( 1985); J. Zhang et al., J. Am. Chem. Soc., Vol. 116, page 2655 (1994)). The polymerization of discotic liquid crystalline molecules is described in JP-A-8-27284.

  Furthermore, various compounds having functional groups or sites that can react by heat or photocrosslinking reaction or the like in the liquid crystal substance may be blended within a range that does not hinder the development of liquid crystallinity. Examples of the functional group capable of undergoing a crosslinking reaction include the various reactive functional groups described above.

For example, when the poly (meth) acrylate represented by the formula (1) is used, it is preferable to contain a dioxetane compound represented by the following general formula (2).

In the formula (2), each R ⁷ independently represents hydrogen, a methyl group or an ethyl group, and each L ³ independently represents a single bond or — (CH ₂ ) _n — (n is an integer of 1 to 12) X ¹ represents each independently a single bond, —O—, —O—CO— or —CO—O—, and M ¹ is represented by formula (3) or formula (4). P ¹ in formulas (3) and (4) each independently represents a group selected from formula (5), P ² represents a group selected from formula (6), and L ⁴ Each independently represents a single bond, —CH═CH—, —C≡C—, —O—, —O—CO— or —CO—O—.
-P ¹ -L ⁴ -P ² -L ⁴ -P ^1- (3)
-P ¹ -L ⁴ -P ^1- (4)

In the formulas (5) and (6), Et represents an ethyl group, iPr represents an isopropyl group, nBu represents a normal butyl group, and tBu represents a tertiary butyl group.
More specifically, the linking groups connecting the left and right oxetanyl groups as viewed from the M ¹ group may be different (asymmetric) or the same (symmetric), particularly when two L ³ are different or other Depending on the structure of the linking group, it may not exhibit liquid crystallinity, but it is not a restriction for use.
The compound represented by the general formula (2) can be exemplified by many compounds from the combination of M ¹ , L ³ and X ¹ , and preferably the following compounds can be mentioned.

These compounds can be synthesized according to a usual synthesis method in organic chemistry, and the synthesis method is not particularly limited.
In the synthesis, since the oxetanyl group has cationic polymerizability, it is necessary to select reaction conditions in consideration of causing side reactions such as polymerization and ring opening under strong acidic conditions. The oxetanyl group is less likely to cause a side reaction than an oxiranyl group that is a similar cationically polymerizable functional group. Furthermore, various compounds such as similar alcohols, phenols, carboxylic acids and the like may be reacted one after another, and utilization of protecting groups may be considered as appropriate.

  As a more specific synthesis method, for example, hydroxybenzoic acid is used as a starting compound, an oxetanyl group is bound by Williamson's ether synthesis method, etc., and then the resulting compound and a diol suitable for the present invention are combined with an acid chloride. Or by condensing using a carbodiimide condensation method or the like, or conversely protecting the hydroxyl group of hydroxybenzoic acid with an appropriate protecting group in advance, condensing with a diol suitable for the present invention, removing the protecting group, and Examples thereof include a method of reacting a hydroxyl group with a compound having an oxetanyl group (oxetane compound), for example, a haloalkyloxetane or the like.

  For the reaction between the oxetane compound and the hydroxyl group, a reaction condition suitable for the form and reactivity of the compound used may be selected. Usually, the reaction temperature is -20 ° C to 180 ° C, preferably 10 ° C to 150 ° C. The reaction time is 10 minutes to 48 hours, preferably 30 minutes to 24 hours. Outside these ranges, the reaction does not proceed sufficiently or side reactions occur, which is not preferable. Moreover, the mixing ratio of both is preferably 0.8 to 1.2 equivalents of the oxetane compound per equivalent of hydroxyl group.

  The reaction can be carried out without solvent, but is usually carried out in a suitable solvent. The solvent used is not particularly limited as long as it does not interfere with the intended reaction. For example, aromatic hydrocarbons such as benzene, toluene and xylene, amides such as dimethylformamide, dimethylacetamide and N-methylpyrrolidone, methyl ethyl ketone, Examples include ketones such as methyl isobutyl ketone, ethers such as dibutyl ether, ethylene glycol dimethyl ether and diethylene glycol dimethyl ether, esters such as ethyl acetate and ethyl benzoate, halogenated hydrocarbons such as chloroform and dichloromethane, and mixtures thereof. .

  Even if the liquid crystal substance used in the present invention is the above-mentioned liquid crystal compound alone or a mixture containing various liquid crystal compounds and various activators and additives, the whole exhibits liquid crystal properties. That's fine. These liquid crystalline compositions contain at least 10% by mass, preferably 30% by mass or more, and more preferably 50% by mass or more of the above low-molecular liquid crystal substance or polymer liquid crystal substance, and exhibit liquid crystallinity. . When the content of the low-molecular liquid crystal substance or the high-molecular liquid crystal substance is less than 10% by mass, the concentration of the compound exhibiting liquid crystallinity in the composition becomes low, and the composition may not exhibit liquid crystallinity, which is not preferable.

As described above, the liquid crystalline composition in the present invention can contain various compounds that can be mixed without impairing liquid crystallinity in addition to the low-molecular liquid crystal substance or the high-molecular liquid crystal substance. Examples of compounds that can be contained include various polymerizable compounds having a radical polymerizable group such as a vinyl group and a (meth) acryloyl group, and a cationic polymerizable group such as an oxetanyl group, an oxiranyl group, and a vinyloxy group, a carboxyl group, and an amino group. A compound having a reactive group such as a group or an isocyanate group, or various polymer compounds having film-forming ability can also be blended. In addition, when a surfactant, antifoaming agent, leveling agent, etc., or a compound having a reactive functional group or a low-molecular or high-molecular liquid crystal substance is used, a reaction initiator or activity suitable for each functional group is used. Agents, sensitizers and the like may be added within a range not departing from the object of the present invention.
A liquid crystalline composition having a reactive group is obtained by achieving a desired alignment and then reacting under a condition suitable for reacting the reactive group to achieve a desired final product by crosslinking or increasing molecular weight. It is also possible to contribute to the improvement of the mechanical strength and the like.

Examples of the reaction initiator include organic peroxides, azo compounds and various photopolymerization initiators used for general radical polymerization.
Examples of the photopolymerization initiator include a photo radical initiator that cleaves with appropriate light to generate radicals, and a photo cation generator that cleaves with appropriate light to generate cations. If necessary, a thermal cation generator that can generate cations when heated to an appropriate temperature can also be used.

  As the photo radical initiator, commercially available benzoin ethers, acyl phosphine oxides, triazine derivatives, biimidazole derivatives generally used for known ultraviolet (UV) curable paints, UV curable adhesives, negative resists, etc. And the like.

Examples of the photocation generator include organic sulfonium salt systems, iodonium salt systems, and phosphonium salt systems. Antimonates, phosphates, borates and the like are preferably used as counter ions of these compounds. Specific examples of the compound include Ar ₃ S ⁺ SbF ₆ ⁻ , Ar ₃ P ⁺ BF ₄ ⁻ and Ar ₂ I ⁺ PF ₆ ⁻ (wherein Ar represents a phenyl group or a substituted phenyl group). In addition, sulfonate esters, triazines, diazomethanes, β-ketosulfone, iminosulfonate, benzoinsulfonate, and the like can also be used.

  Examples of the thermal cation generator include benzylsulfonium salts, benzylammonium salts, benzylpyridinium salts, benzylphosphonium salts, hydrazinium salts, carboxylic acid esters, sulfonic acid esters, amine imides, antimony pentachloride-acetyl chloride complex , Diaryl iodonium salt-dibenzyloxy copper, boron halide-tertiary amine adduct, and the like.

  The amount of these reaction initiators added to the liquid crystal composition varies depending on the structure of the mesogen part and spacer part, the molecular weight, the alignment condition of the liquid crystal, etc. constituting the liquid crystal compound to be used. On the other hand, it is usually in the range of 100 mass ppm to 20 mass%, preferably 1000 mass ppm to 10 mass%, more preferably 0.5 mass% to 7 mass%. If the amount is less than 100 mass ppm, the amount of active species generated from the reaction initiator may not be sufficient and the reaction may not proceed. If the amount is more than 20 mass%, it remains in the liquid crystal composition. This is not preferable because there is a risk that the decomposition residue of the reaction initiator and the like increase in color and the light resistance and the like deteriorate.

  Next, a method for forming a liquid crystal material layer with a fixed orientation and a method for producing a liquid crystal film of the present invention will be described. However, the method for forming a liquid crystal material layer and the method for producing a liquid crystal film of the present invention are not limited to these. is not.

First, a liquid crystalline composition is developed on an alignment substrate.
As alignment substrates, polyimide, polyamide, polyamideimide, polyphenylene sulfide, polyphenylene oxide, polyether ketone, polyether ether ketone, polyether sulfone, polysulfone, polyethylene terephthalate, polyethylene naphthalate, polyarylate, triacetyl cellulose, epoxy resin, A film such as a phenol resin can be exemplified.

Some of these films exhibit a sufficient alignment ability for the liquid crystal substance used in the present invention without performing a treatment for expressing the alignment ability again depending on the production method, but the alignment ability is insufficient, or When the orientation ability is not exhibited, these films are stretched under moderate heating, the film surface is rubbed in one direction with a rayon cloth or the like, so-called rubbing treatment is performed, polyimide, polyvinyl alcohol, silane cup on the film A film that exhibits orientation ability by providing an orientation film made of a known orientation agent such as a ring agent and performing rubbing treatment, oblique vapor deposition treatment such as silicon oxide, or a combination thereof may be used.
Further, as the alignment substrate, a metal plate such as aluminum, iron, or copper having various regular fine grooves on the surface, various glass plates, or the like can be used.

  Here, the direction (orientation) of the alignment treatment applied to the alignment substrate is not particularly limited, and can be appropriately selected by performing each of the above treatments in an arbitrary direction. In particular, when a liquid crystal material layer is formed on a long alignment substrate, it is desirable to select a desired angle with respect to the length direction (MD) of the long film and perform alignment treatment. By laminating a liquid crystal film on a polarizing plate or a retardation film with an axial arrangement that can exhibit optimal optical characteristics by aligning the film in a desired angular direction, it is necessary to apply a long film with MD aligned. This is extremely advantageous from the viewpoints of enabling bonding (so-called roll-to-roll bonding) or increasing the efficiency of taking products.

The liquid crystal composition can be spread on the alignment substrate to form a liquid crystal material layer. The liquid crystal composition can be applied directly on the alignment substrate in a molten state, or the liquid crystal composition solution can be applied on the alignment substrate. And a method of drying the coating film and distilling off the solvent.
The solvent used for preparing the solution is not particularly limited as long as it can dissolve various compounds used in the liquid crystalline composition and can be distilled off under appropriate conditions, and generally includes acetone, methyl ethyl ketone, isophorone, cyclohexanone, and the like. Ketones, butoxyethyl alcohol, hexyloxyethyl alcohol, ether alcohols such as methoxy-2-propanol and benzyloxyethyl alcohol, glycol ethers such as ethylene glycol dimethyl ether and diethylene glycol dimethyl ether, ethyl acetate, ethyl lactate, γ-butyrolactone, etc. Esters, phenols such as phenol and chlorophenol, amides such as N, N-dimethylformamide, N, N-dimethylacetamide and N-methylpyrrolidone, Arm, tetrachloroethane, halogenated such or a mixture of these systems, such as dichlorobenzene are preferably used. Further, in order to form a uniform coating film on the alignment substrate, a surfactant, an antifoaming agent, a leveling agent, or the like may be added to the solution.

  There is no particular limitation on the application method, either a method of directly applying a liquid crystalline composition or a method of applying a solution, as long as the uniformity of the coating film is ensured, and a known method is adopted. be able to. For example, a flexographic printing method, an offset printing method, a dispenser method, a gravure coating method, a micro gravure method, a bar coating method, a screen printing method, a lip coating method, a die coating method, and the like can be given. Of these, gravure coating, kiss coating, lip coating and die coating are preferred.

In the method of applying the liquid crystal composition solution, it is preferable to include a drying step for removing the solvent after the application. As long as the uniformity of a coating film is maintained, this drying process can employ | adopt a well-known method, without being specifically limited. For example, a method such as a heater (furnace) or hot air blowing may be used.
The coating film thickness is not determined unconditionally because it is adjusted depending on the liquid crystal composition to be used and the use of the resulting birefringent layer, etc., but is 0.1 to 50 μm, preferably 0.2 to 0.5 mm after drying. It is 20 μm, more preferably 0.3 to 10 μm. If the film thickness is outside this range, the desired effect cannot be obtained, and the orientation becomes insufficient.

  Subsequently, after aligning the liquid crystal in the liquid crystal material layer formed on the alignment substrate by a method such as heat treatment, a reactive group is reacted by light irradiation and / or heat treatment as necessary to fix the alignment. In the first heat treatment, the liquid crystal is aligned by the self-alignment ability inherent in the liquid crystalline composition by heating to a desired temperature within the liquid crystal phase expression temperature range of the used liquid crystalline composition. As the conditions for the heat treatment, the optimum conditions and limit values differ depending on the liquid crystal phase behavior temperature (transition temperature) of the liquid crystal composition to be used, but it cannot be generally stated, but is usually 10 to 300 ° C., preferably 20 to 250 ° C. It is preferable that the heat treatment be performed at a temperature not lower than the glass transition point (Tg) of the liquid crystalline composition, more preferably not lower than 10 ° C. higher than Tg. If the temperature is too low, the liquid crystal alignment may not proceed sufficiently, and if the temperature is high, the liquid crystal composition and the alignment substrate may be adversely affected. Moreover, about heat processing time, it is 3 seconds-30 minutes normally, Preferably it is the range of 10 seconds-10 minutes. If the heat treatment time is shorter than 3 seconds, the liquid crystal alignment may not be completed sufficiently, and if the heat treatment time exceeds 30 minutes, the productivity is deteriorated.

  After forming the liquid crystal material layer by the above-described method, when a liquid crystal composition containing a reactive group is used, the liquid crystal composition is included in the composition while maintaining the liquid crystal alignment state. The function of the reaction initiator is expressed and the reactive group is reacted to fix the orientation.

When the reaction initiator exhibits the function of the initiator by light irradiation, the light irradiation method includes a metal halide lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a low pressure mercury lamp having a spectrum in the absorption wavelength region of the reaction initiator used. The reaction initiator is activated by irradiating light from a light source such as a xenon lamp, an arc lamp, or a laser. The dose per square centimeter is usually in the range of 1 to 2000 mJ, preferably 10 to 1000 mJ as the cumulative dose. However, this is not the case when the absorption region of the reaction initiator and the spectrum of the light source are significantly different, or when the liquid crystalline composition itself has the ability to absorb light of the light source wavelength. In these cases, an appropriate photosensitizer, or a mixture of two or more reaction initiators having different absorption wavelengths may be used.
The temperature at the time of light irradiation is preferably a temperature range in which the liquid crystalline composition takes liquid crystal alignment. In order to sufficiently enhance the reaction effect, light irradiation is performed at a liquid crystal phase temperature equal to or higher than Tg of the liquid crystalline composition. Is preferred.

Thus, a liquid crystal material layer in which the alignment is fixed is formed on the alignment substrate.
Then, the liquid crystal film adhesive is applied to the liquid crystal material layer or a substrate different from the alignment substrate described later by a method suitable for the adhesive, and if necessary, a drying treatment such as a solvent is applied to form an adhesive layer. The liquid crystal film of the present invention can be obtained by forming and attaching a liquid crystal substance layer and a substrate different from the alignment substrate, curing the substrate if necessary, and then peeling the alignment substrate.

  The curing method is not particularly limited, and examples thereof include heat curing, redox room temperature curing, anaerobic curing, and curing with active rays such as ultraviolet rays and electron beams. A preferable curing method is a curing method using active rays such as ultraviolet rays and electron beams. In particular, a curing method using actinic radiation is preferable because it has a fast reaction and has little influence on the liquid crystal material layer in which the alignment is fixed. For curing, light from a light source such as a metal halide lamp, high-pressure mercury lamp, ultra-high pressure mercury lamp, low-pressure mercury lamp, xenon lamp, arc lamp, laser or synchrotron radiation source is applied to the adhesive layer to which the photopolymerization initiator is added. Irradiation can be performed. The amount of irradiation per unit area (one square centimeter) is usually in the range of 1 to 2000 mJ, preferably 10 to 1000 mJ as the integrated irradiation amount. However, this is not the case when the absorption region of the photopolymerization initiator and the spectrum of the light source are significantly different, or when the compound to be reacted itself has the ability to absorb the light source wavelength. In these cases, an appropriate photosensitizer or a method of using a mixture of two or more photoinitiators having different absorption wavelengths can be used. The acceleration voltage in the case of curing with an electron beam is usually 10 kV to 200 kV, preferably 20 kV to 100 kV.

  As the substrate (film) different from the alignment substrate, polyolefin resins such as polyethylene, polypropylene, poly (4-methylpentene-1), amorphous polyolefin, poly (cycloolefin), polyamide, polyimide, polyamideimide, poly Ether imide, polyether ketone, polyether ether ketone, polyether sulfone, polyketone sulfide, polysulfone, polystyrene, polyphenylene oxide, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyarylate, polyacetal, uniaxially stretched polyester, polycarbonate, polyvinyl alcohol , Polymethyl methacrylate, polyarylate, triacetyl cellulose, or epoxy resin Lum can be used.

In particular, as a transparent and optically isotropic film having excellent inspection of optical defects, poly (4-methylpentene-1), polymethyl methacrylate, polystyrene, polycarbonate, polyethersulfone, polyarylate, amorphous polyolefin Plastic films such as poly (cycloolefin), triacetyl cellulose, or epoxy resin are preferably used.
In particular, the adhesive of the present invention can particularly suppress the deterioration of the adhesion with time with triacetylcellulose among these transparent films.

In addition, these films temporarily support the liquid crystal material layer in the final form of the liquid crystal film or optical element film of the present invention when the liquid crystal material layer functions as a support substrate and before the optical element film is produced. Depending on the case of having a function as a temporary substrate, it can be appropriately selected.
Furthermore, these films have an organic thin film or an inorganic thin film formed on the surface in advance for the purpose of adjusting the adhesive force, or have been subjected to a treatment such as a corona discharge treatment or an easily peelable silicone treatment. Also good.
In the case of a temporary substrate, a known film may be used as a so-called separator film.

  The thickness of these films is preferably 10 to 100 μm, particularly preferably 25 to 50 μm. If the thickness is too thick, the peeling point may not be stable when the alignment substrate is peeled off, and the peelability may be deteriorated. On the other hand, if the thickness is too thin, the mechanical strength of the film cannot be maintained. There is a fear.

  In order to protect the surface of the liquid crystal substance layer after the alignment substrate is peeled off, a surface protective layer may be provided. Examples of the surface protective layer include the above-mentioned adhesives, other adhesives, and protective films made of polymer films. Can do.

The optical element film of the present invention will be described.
The optical element film of the present invention is a laminate obtained by combining the liquid crystal film, a polarizing plate, and various retardation films.

  The polarizing plate is not particularly limited, and a polarizing plate (film) usually used in a liquid crystal display device can be used as appropriate, but a thin film type that has been recently developed and marketed is desirable. Specifically, iodine and / or dichroism is applied to a hydrophilic polymer film made of a PVA polarizing film such as polyvinyl alcohol (PVA) or partially acetalized PVA, or a partially saponified ethylene-vinyl acetate copolymer. A polarizing film formed by adsorbing a dye and stretching, a polarizing film composed of a polyene oriented film such as a dehydrated PVA product or a dehydrochlorinated polyvinyl chloride product, and the like can be used. A reflective polarizing film can also be used.

  The polarizing plate may be used alone, or may be provided with a transparent protective layer or the like on one side or both sides of the polarizing film for the purpose of improving strength, improving moisture resistance, improving heat resistance, etc. good. Transparent protective layers include transparent plastic films such as polyester, poly (cycloolefin), and triacetyl cellulose laminated directly or via an adhesive layer or adhesive layer, resin coating layers, acrylic or epoxy systems And a photo-curable resin layer. When these transparent protective layers are coated on both surfaces of the polarizing film, protective layers made of the same material may be provided on both surfaces, or protective layers made of different materials may be provided.

  The retardation film has optical properties (optical anisotropy) to be described later, and is not particularly limited as long as it is long. For example, a retardation film composed of a birefringent polymer film, a retardation film that is heated after a polymer compound is coated on a transparent support and developed to exhibit birefringence, and a low-molecular or high-molecular liquid crystalline compound on the transparent support Any of a retardation film having a retardation layer formed by coating or transferring a film can be used. Moreover, each can also be laminated | stacked and used.

  The optical properties (optical anisotropy) of the retardation film are defined as Re = (nx−ny) × d using the in-plane refractive indexes nx and ny (nx ≧ ny) and the film thickness d. It is represented by in-plane retardation (Re). Although there is no particular limitation on the range of Re, in general, those within a range called a quarter-wave plate and a half-wave plate are preferable, and the former Re is 60 to 200 nm, preferably 70 to 180 nm, more preferably. Is 90 to 160 nm, and the latter Re is 180 to 320 nm, preferably 200 to 300 nm, more preferably 220 to 280 nm. Note that Re is a value measured at a wavelength of 550 nm.

  The retardation film may be formed from a polymer film. The polymer film is formed from a polymer capable of developing birefringence. As the birefringent polymer film, those having excellent controllability of birefringence characteristics, transparency and heat resistance, and those having low photoelasticity are preferable. In this case, the polymer material to be used is not particularly limited as long as it is a polymer that can achieve uniform uniaxial orientation or biaxial orientation, and is preferably a conventionally known material that can be formed by a solution casting method or an extrusion method. , Norbornene polymer, polycarbonate polymer, polyarylate polymer, polyester polymer, aromatic polymer such as polysulfone, polyolefin such as polypropylene, cellulose acylate, or two or three of these polymers Examples thereof include a polymer obtained by mixing the above.

  The birefringence (optical anisotropy) of the polymer film is preferably expressed by uniaxial or biaxial stretching. Uniaxial stretching is preferably longitudinal uniaxial stretching using the difference in peripheral speed between two or more rolls, or tenter stretching in which both sides of the polymer film are gripped and stretched in the width direction. Further, biaxial optical anisotropy may be developed by stretching the polymer film in the longitudinal direction and the transverse direction. In addition, using two or more polymer films, the optical properties of the entire two or more films may satisfy the above conditions. The polymer film is preferably produced by a solvent cast method in order to reduce unevenness in birefringence. The thickness of the polymer film is preferably 20 to 400 μm, and most preferably 30 to 100 μm. A polarizing film using iodine, which is widely used, is manufactured by a continuous longitudinal uniaxial stretching process, and therefore has an absorption axis parallel to the longitudinal direction of the roll. Therefore, the long polarizing film stretched in a general longitudinal uniaxial direction and the long first optically anisotropic layer have the absorption axis of the polarizing film orthogonal to the slow axis of the first optically anisotropic layer. Thus, when laminating by roll-to-roll, it is preferable to use a transverse stretching machine so that the slow axis is orthogonal to the transport direction.

The retardation film may be formed as a layer (film) in which a low molecular weight or high molecular liquid crystalline compound is oriented.
The liquid crystalline compound is preferably fixed in an aligned state, and more preferably fixed by polymerization. As long as the optical characteristics are satisfied, the type of the liquid crystalline compound is not particularly limited. For example, a layer (film) obtained by forming a desired orientation in a liquid crystal state of a low-molecular liquid crystalline compound and then fixing the orientation by polymerization or cross-linking reaction with actinic rays, electron beam, heat, etc., or polymer liquid crystal A layer (film) or the like obtained by fixing the alignment by forming a desired compound in a liquid crystal state and then cooling, or by causing polymerization or a crosslinking reaction in the same manner as in the case of a low molecular liquid crystal compound. Can be used. The layer (film) obtained by fixing the orientation can be used with or without a support.
Examples of the alignment phase of the liquid crystal compound include a smectic phase, a nematic phase, and a twisted nematic phase. Examples of the alignment form include homogeneous alignment, homeotropic alignment, tilt alignment, and hybrid alignment.
In the present invention, the liquid crystal layer in which the alignment is fixed is a layer formed by fixing the alignment of the liquid crystalline compound by polymerization or the like, and it is no longer necessary to exhibit liquid crystallinity after forming the layer. . As a liquid crystalline compound, it can select from the above-mentioned liquid crystal substance suitably.

  The optical element film of the present invention is a laminate obtained by combining a liquid crystal film, a polarizing plate, and various retardation films, and the laminated body usually has a displacement or distortion in each film or polarizing plate constituting the laminate. It is formed using an adhesive or a pressure-sensitive adhesive so as not to occur.

The pressure-sensitive adhesive can be made of an optically transparent material or a light diffusing material. Adhesives, also called pressure sensitive adhesives, are adhered to the surface of other substances simply by pressing them, and when they are peeled off from the adherend surface, they can be removed with almost no trace as long as the adherend has strength. It is a viscoelastic body. As the adhesive, acrylic, vinyl chloride, synthetic rubber, natural rubber, silicone, etc. can be used. From these, transparent and optically isotropic What is necessary is just to select and use. These pressure-sensitive adhesives may be reactive such as a photo-curing type. Moreover, the adhesive agent for liquid crystal films of this invention can also be used.
Of these, acrylic pressure-sensitive adhesives are preferred from the viewpoints of handling properties and transparency.

When a reactive pressure-sensitive adhesive is used, conditions that do not adversely affect the resulting optical element film and cause a reaction (curing) suitable for the reactivity may be used.
The curing method is not particularly limited, and examples thereof include heat curing, redox room temperature curing, anaerobic curing, and active ray curing such as ultraviolet rays and electron beams. A preferable curing method is a curing method using active rays such as ultraviolet rays and electron beams. In particular, a curing method using actinic radiation is preferable because it has a fast reaction and has little influence on the liquid crystal material layer in which the alignment is fixed. For curing, light from a light source such as a metal halide lamp, high-pressure mercury lamp, ultra-high pressure mercury lamp, low-pressure mercury lamp, xenon lamp, arc lamp, laser, synchrotron radiation light source is applied to the adhesive layer to which the photopolymerization initiator is added. Irradiation can be performed. The amount of irradiation per unit area (one square centimeter) is usually in the range of 1 to 2000 mJ, preferably 10 to 1000 mJ as the integrated irradiation amount. However, this is not the case when the absorption region of the photopolymerization initiator and the spectrum of the light source are significantly different, or when the compound to be reacted itself has the ability to absorb the light source wavelength. In these cases, an appropriate photosensitizer, or a method of using a mixture of two or more photopolymerization initiators having different absorption wavelengths can be used. The acceleration voltage in the case of curing with an electron beam is usually 10 kV to 200 kV, preferably 20 kV to 100 kV.

The light diffusable pressure-sensitive adhesive is one in which fine particles are dispersed in the pressure-sensitive adhesive as described above to express light diffusibility. As fine particles blended to express light diffusibility, silicon dioxide called titanium, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, Examples thereof include aluminum silicate, magnesium silicate and calcium phosphate, and polymer fine particles such as polymethyl methacrylate and polystyrene.
The haze of the light diffusing pressure-sensitive adhesive is preferably 20% or more, more preferably 40% or more, and particularly preferably 60% or more. The haze is a value defined in JIS K 7105, and is represented by (diffuse transmittance / total light transmittance) × 100 (%).

  In addition, the thickness of each pressure-sensitive adhesive is 0.5 to 50 μm, desirably 1 to 30 μm, and more desirably 3 to 20 μm. If the thickness is too thin, the adhesive force tends to be insufficient and adhesion becomes difficult, and if it is too thick, it may ooze from the end portion and cause a defective product appearance.

The optical element film of the present invention has various forms depending on the laminated form regardless of the presence or absence of a support substrate or a temporary substrate.
(1) Polarizing plate / viscous / adhesive layer / liquid crystal film / viscous / adhesive layer (/ separator)
(2) Polarizing plate / viscous / adhesive layer / retardation film / viscous / adhesive layer / liquid crystal film / viscous / adhesive layer (/ separator)
(3) Structures of polarizing plate / viscous / adhesive layer / liquid crystal film / viscous / adhesive layer / retardation film can be exemplified. The above-mentioned “viscous / adhesive layer” means a pressure-sensitive adhesive layer or an adhesive layer, and “/” means an interface of each layer.
Furthermore, a plurality of retardation films can be laminated.

  The optical element film of the present invention may be formed by appropriately laminating each film so as to have a target layer structure. When a temporary substrate is used as a substrate different from the alignment substrate, the liquid crystal film is used in the example of (2) above. After sequentially sticking a retardation film and a polarizing plate to the liquid crystal layer side, the temporary substrate is peeled off to form an adhesive / adhesive layer, or after attaching a retardation film to the liquid crystal layer side of the liquid crystal film, After the temporary substrate is peeled off and the adhesive / adhesive layer attached with a separator is formed, it can be produced by a method of sticking a polarizing plate on the surface of the retardation film.

The liquid crystal film and optical element film of the present invention can be used for liquid crystal cells and liquid crystal display devices in various display modes depending on the liquid crystal material layer constituting the liquid crystal film and the optical anisotropy of the retardation film.
For example, TN (Twisted Nematic), IPS (In-Plane Switching), OCB (Optically Compensatory Bend), ECB (Electrically Controlled Birefringence), STN (Supper Twisted Nematic), VA (Vertically Aligned) and HAN (Hybrid Aligned Nematic) Various display modes can be mentioned.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In addition, each analysis method used in the Example is as follows.

(1) Observation of phase behavior The phase behavior was observed with a BH2 polarizing microscope manufactured by Olympus Optical Co., Ltd. while heating the sample on a hot stage FP82HT manufactured by Mettler.
The phase transition temperature was measured with a differential scanning calorimeter DSC7 manufactured by Perkin-Elmer.
(2) Measurement of logarithmic viscosity of polymer liquid crystal substance It was measured at 30 ° C. in a phenol / tetrachloroethane (60/40: mass ratio) mixed solvent using an Ubbelohde viscometer.
(3) Measurement of molecular weight (GPC measurement)
The compound was dissolved in tetrahydrofuran, TSK-GELSuperH1000, SuperH2000, SuperH3000, and SuperH4000 were connected in series with an 8020 GPC system manufactured by Tosoh Corporation, and measurement was performed using tetrahydrofuran as an eluent. Polystyrene standards were used for molecular weight calibration.
(4) Parameter measurement of liquid crystal film The retardation value (Δnd) of the aligned liquid crystal material layer and the like was measured with KOBRA-21ADH manufactured by Oji Scientific Instruments using light having a wavelength of 550 nm.
(5) Film thickness measurement SURFACE TEXTURE ANALYSIS SYSTEM Dektak 3030ST manufactured by SLOAN was used. Moreover, the method of calculating | requiring a film thickness from the data of interference wave measurement (The JASCO Corporation UV / visible / near infrared spectrophotometer V-570) and refractive index data was used together.
(6) Measurement of adhesion (peeling force) Strograph E-L II manufactured by Toyo Seiki Seisakusho Co., Ltd. was used. The sample film was fixed on a metal plate with an adhesive, and the peeling force (adhesion force) when peeled 180 ° at room temperature was measured at a peeling speed of 300 mm / min.

[Preparation Example 1]
Polycondensation was performed at 270 ° C. for 12 hours in a nitrogen atmosphere using 50 mmol of terephthalic acid, 50 mmol of 2,6-naphthalenedicarboxylic acid, 40 mmol of methylhydroquinone diacetate, 60 mmol of catechol diacetate and 60 mg of N-methylimidazole. Next, the obtained reaction product was dissolved in tetrachloroethane, and then purified by reprecipitation with methanol to obtain 14.6 g of a liquid crystalline polyester. This liquid crystalline polyester (Polymer 1) has a logarithmic viscosity of 0.16 dl / g, a nematic phase as a liquid crystal phase, an isotropic phase-liquid crystal phase transition temperature of 250 ° C. or higher, and a glass transition temperature by a differential scanning calorimeter (DSC). Was 112 ° C.
A solution was prepared by dissolving 20 g of Polymer 1 in 80 g of N-methyl-2-pyrrolidone. This solution is applied onto a polyimide film (trade name “Kapton”, manufactured by DuPont) rubbed with a rayon cloth, and the solvent is dried and removed, followed by heat treatment at 210 ° C. for 20 minutes for nematic orientation. A structure was formed. After the heat treatment, the nematic alignment structure was fixed by cooling to room temperature to obtain a liquid crystal material layer 1 uniformly aligned with an actual film thickness of 0.7 μm on the polyimide film.
In order to measure Δnd of the liquid crystal material layer 1, the adhesive layer surface of the triacetyl cellulose (TAC) film with adhesive (manufactured by Fuji Film Co., Ltd.) and the liquid crystal material layer 1 are attached, and then the polyimide film is attached. It peeled. As a result of measuring Δnd of the obtained laminated film and correcting the Δnd value of the triacetyl cellulose film with an adhesive separately measured, Δnd of the liquid crystal material layer 1 was 128 nm.

[Preparation Example 2]
(Preparation of liquid crystalline composition solution)
A liquid crystal composition solution used for the production of the liquid crystal material layer 2 was prepared as follows.
A liquid crystalline polymer represented by the following formula (7) was synthesized by ordinary radical polymerization. The molecular weight was, in terms of polystyrene, number average molecular weight (Mn) = 8000 and weight average molecular weight (Mw) = 15000.
200.0 g of this liquid crystalline polymer was dissolved in 1800 ml of cyclohexanone, 20 g of a triallylsulfonium hexafluoroantimonate 50% propylene carbonate solution (manufactured by Aldrich) was added in the dark, and then the pore size was 0.45 μm. A liquid crystalline composition solution was prepared by filtration through a polytetrafluoroethylene filter.
In addition, although following formula (7) is displayed with the form of a block copolymer, it displays the monomer composition ratio (mol ratio) at the time of superposition | polymerization.

(Formation of alignment film)
A polyvinyl alcohol [PVA; (PVA; (PVA; Product name AT, manufactured by Nippon Vinegar Poval Co., Ltd., composition: powder composed of 53% PVA component and 47% water)] solution (PVA 4 mass%, solvent composition: water / isopropyl alcohol = 80/20 mass ratio) ) The solution was applied continuously. The coating film was continuously dried at a relative drying air speed of 600 m / min with a hot air circulation drier set at 50 ° C., 70 ° C., 90 ° C. and 130 ° C. to obtain a long film with an alignment film.

(Rubbing process)
While the long film with the alignment film obtained above is conveyed at a speed of 20 m / min, a rubbing roll having a diameter of 150 mm around which the rubbing cloth is wound is set at 45 degrees with respect to the MD of the film. The cloth was rubbed continuously by rotating the bristles of the cloth at a pressure of 500 μm and rotating at 1500 rpm (circumferential speed ratio 35), and was wound on a roll.

(Preparation of liquid crystal substance layer 2)
The liquid crystalline composition solution obtained above was applied on the rubbing-treated long film using a roll coater so that the liquid crystal material layer thickness after orientation and curing was 1 μm, and then dried at 60 ° C. Thereafter, the liquid crystal material layer is aligned by heat treatment at 140 ° C. for 2 minutes, and then irradiated with 300 mJ / cm ² of ultraviolet light with an ultraviolet irradiation device equipped with a high-pressure mercury lamp maintained at an ambient temperature of 70 ° C. The orientation was fixed and cooled to room temperature to obtain a film having a liquid crystal material layer 2 / PVA layer / PEN layer structure.
In the same manner as in Preparation Example 1, in order to measure Δnd of the liquid crystal material layer 2, the pressure-sensitive adhesive layer surface of the triacetyl cellulose (TAC) film (manufactured by FUJIFILM Corporation) and the liquid crystal material layer 2 are attached. Then, it peeled between the liquid crystal substance layer 2 and the PVA layer. As a result of measuring Δnd of the obtained laminated film and correcting the Δnd value of the triacetyl cellulose (TAC) film with adhesive (manufactured by FUJIFILM Corporation) separately measured, Δnd of the liquid crystal material layer 2 was 92 nm. there were.

[Example 1]
UV obtained by adding 30 parts by mass of N, N-dimethylacrylamide to 70 parts by mass of UV curable acrylic adhesive (UV-3400 manufactured by Toagosei Co., Ltd.) on the liquid crystal material layer 1 obtained in Preparation Example 1. A curable acrylic adhesive was applied as an adhesive 1 to a thickness of 5 μm, and a 50 μm-thick triacetyl cellulose (TAC) film (manufactured by Fuji Film Co., Ltd.) was laminated thereon as a support substrate. The adhesive 1 was cured by UV irradiation. Thereafter, the TAC / adhesive 1 / liquid crystal material layer 1 / polyimide film is peeled off from the laminate in which the TAC / adhesive 1 / liquid crystal material layer 1 / polyimide film is integrated to transfer the liquid crystal material layer 1 to the triacetyl cellulose film. A liquid crystal film 1 comprising the liquid crystal material layer 1 was obtained.
Further, a UV curable acrylic adhesive (UV-3400) is applied to the liquid crystal material layer 1 of the liquid crystal film 1 to a thickness of 5 μm, a separator film is laminated thereon, and the UV irradiation of about 600 mJ UV-3400 was cured to obtain a liquid crystal film 2 composed of TAC / adhesive 1 / liquid crystal substance layer 1 / UV-3400 (/ separator).

[Example 2]
It replaced with the adhesive agent 1 used in Example 1, and implemented except having used the adhesive agent 2 which contained 30 mass parts of N, N- diethyl acrylamide in 70 mass parts of UV curable acrylic adhesives (UV-3400). In the same manner as in Example 1, a liquid crystal film 3 composed of TAC / adhesive 2 / liquid crystal substance layer 1 / UV-3400 (/ separator) was obtained.

[Comparative Example 1]
TAC / UV-3400 / liquid crystal substance layer 1 / UV, except that the adhesive 1 used in Example 1 was replaced with a UV curable acrylic adhesive (UV-3400). A laminate comprising -3400 (/ separator) was obtained.

[Comparative Example 2]
Example except that the adhesive 1 used in Example 1 was replaced with the adhesive 3 containing 60 parts by mass of N, N-dimethylacrylamide in 40 parts by mass of UV curable acrylic adhesive (UV-3400). 1 to obtain a laminate composed of TAC / adhesive 3 / liquid crystal substance layer 1 / UV-3400 (/ separator).

[Example 3]
Instead of the adhesive 1 used in Example 1, an adhesive 4 containing 5 parts by mass of acryloylmorpholine in 95 parts by mass of a UV curable acrylic adhesive (UV-3400) was used, and the liquid crystal substance layer 1 was replaced by a liquid crystal substance. A liquid crystal film 4 composed of TAC / adhesive 4 / liquid crystal material layer 2 / UV-3400 (/ separator) was obtained except that layer 2 was used and triacetylcellulose was used as a temporary substrate. .

[Comparative Example 3]
TAC / UV-3400 / Liquid crystal material layer 2 / UV was carried out in the same manner as in Example 3 except that a UV curable acrylic adhesive (UV-3400) was used instead of the adhesive 4 used in Example 3. A laminate comprising -3400 (/ separator) was obtained.

[Performance evaluation 1]
Test (1): 1 mm thick glass plate provided with an adhesive layer in advance after the separator was peeled off from the liquid crystal films 2 and 3 obtained in Examples 1 and 2 and the laminates obtained in Comparative Examples 1 and 2. The test piece adhered to was subjected to an accelerated test under a constant temperature and humidity condition of 60 ° C. and a relative humidity of 90%, and the interlayer adhesion was measured at room temperature. The results are shown in Table 1.
Test (2): The liquid crystal film 4 obtained in Example 3 and the laminate obtained in Comparative Example 3 were stored at room temperature for 3 months and 6 months, and the peel force between the TAC and the adhesive layer was measured. The results are shown in Table 2.

[Example 4]
A 40 μm thick ZEONOR film (manufactured by ZEON Co., Ltd., Δnd) is bonded to a TAC surface of the liquid crystal film 1 on a 38 μm thick separator having a 25 μm thick adhesive layer formed thereon and bonded in advance at a desired angle. Is 275 nm) and a polarizing plate (manufactured by Sumitomo Chemical Co., Ltd.) through a 20 μm thick adhesive, thereby polarizing plate / adhesive layer / Zeonor / adhesive layer / liquid crystal film 1 / adhesive layer / The optical element film 1 consisting of a separator was obtained.

[Example 5]
The same procedure as in Example 4 was performed except that a film having a 25 μm thick adhesive layer formed on a 38 μm thick separator was bonded to the TAC surface of the liquid crystal film 2 and the separator of the liquid crystal film 2 was peeled off. Element film 2 was obtained.

[Comparative Example 4]
A laminate 3 was obtained in the same manner as in Example 4 except that instead of the liquid crystal film 1, the laminate produced in Comparative Example 1 which was stored at room temperature for 1 year was used.

[Performance evaluation 2]
Test (3): Optical element films 1 and 2 and laminate 3 obtained in Examples 4 and 5 and Comparative Example 4 were cut into a rectangular size of 3.5 cm × 4.5 cm, the separator film was peeled off, and then glass Affixed to a plate (2 mm).
Then, the said optical element film etc. were peeled off from the glass plate again, and rework property was confirmed. The results are shown in Table 3.

[Example 6]
After the separator of the liquid crystal film 4 was peeled off, a film on which a pressure-sensitive adhesive layer having a thickness of 25 μm was formed on a separator having a thickness of 38 μm was bonded, and TAC as a temporary substrate was peeled off. Thereafter, a 40 μm-thick ZEONOR film (manufactured by ZEON Co., Ltd., Δnd is 275 nm) and a polarizing plate (manufactured by Sumitomo Chemical Co., Ltd.) bonded in advance through a pressure-sensitive adhesive having a thickness of 20 μm are pasted at a desired angle. By doing this, an optical element film consisting of a polarizing plate / adhesive layer / zeonore / adhesive layer / adhesive 4 / liquid crystal substance layer 2 / UV-3400 / adhesive layer / separator was obtained.

[Comparative Example 5]
An optical element film was obtained in the same manner as in Example 6 except that the laminated body obtained in Comparative Example 3 which had been stored at room temperature for 6 months was used. However, when the separator was peeled off, TAC was used. / Liquid between UV3400 occurred, and the target optical element film was not produced.

Claims (5)

  An adhesive for a liquid crystal film, comprising 1% by mass to 50% by mass of an acrylamide monomer in the adhesive.   A liquid crystal film in which an alignment substrate is peeled off by adhering at least a liquid crystal substance layer on which alignment on the alignment substrate is fixed and a substrate different from the alignment substrate with the adhesive for liquid crystal film according to claim 1.   The liquid crystal material layer in which the alignment is fixed is made of a polymer liquid crystal material that aligns liquid crystal at a temperature equal to or higher than a liquid crystal transition point and enters a glass state at a temperature equal to or lower than the liquid crystal transition point. Liquid crystal film.   The liquid crystal film according to claim 2, wherein the liquid crystal material layer in which the alignment is fixed is a cross-linked liquid crystal material layer in which a low-molecular liquid crystal or a polymer liquid crystal is aligned.   The optical element film using the liquid-crystal film of any one of Claims 2-4.