JP2008242216A - Manufacturing method of optical film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an optical film which uses for an alignment film a composition of polyvinyl alcohol (PVA) such that liquid crystal does not change in alignment performance and a birefringent layer is easily transferred. <P>SOLUTION: The manufacturing method of the optical film comprises the stages of: forming the alignment film on a base material; rubbing the formed alignment film; forming the birefringent layer on the rubbed alignment film; and transferring the formed birefringent layer onto a base material different from base material, the manufacturing method of the optical film being characterized in that the alignment film is made of polyvinyl alcohol containing polyacrylic acid sodium. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical film and a method for producing the same that are useful in the fields of liquid crystal displays, optics, optoelectronics, and the like.

Liquid crystalline films that use liquid crystal as a film material are useful as optical films for liquid crystal displays, etc., but the quality standards required for liquid crystalline films have become increasingly strict in recent years as the display becomes more precise. .
As a method for producing a liquid crystalline film, there is a method in which a thin film of a liquid crystal substance is formed on an alignment substrate to align the liquid crystal and fix the alignment. It is common to use a rubbing-treated substrate as this alignment substrate. The rubbing treatment is performed by rotating a roll around which a cloth (rubbing cloth) is wound and rubbing the traveling substrate. For example, a method in which a substrate on which an alignment film is formed is subjected to a rubbing treatment (see, for example, Patent Documents 1 and 2) or a method in which a plastic film is directly rubbed and used as an alignment substrate film (see, for example, Patent Document 3). ) Etc. are known. The method using the alignment film is advantageous in terms of quality, but has a problem that the formation of the alignment film is expensive and the number of steps increases. Therefore, a method that does not use an alignment film is advantageous in terms of cost and productivity.

  The alignment of the liquid crystal is greatly influenced by the state of the plastic film or sheet serving as the alignment substrate to be used and the surface of the alignment film. The cause is that the alignment regulation force changes due to minute protrusions on the surface or a small amount of impurities on the substrate surface, causing an abnormality in the alignment, resulting in an alignment failure. Although a strong rubbing method has been proposed as a method for strengthening the alignment regulating force, there are increased defects caused by an increase in dust accompanying the rubbing and scratches on the surface to be rubbed. In order to suppress dust generation and scratches, it is desired to increase the hardness of the alignment film material. On the other hand, impurities may be mixed from the manufacturing process, but it is also required to reduce the amount of impurities accompanying the manufacturing process of the alignment film material to reduce the alignment abnormality.

For example, polyvinyl alcohol (PVA) or polyimide is known as an organic material used as an alignment film applied on a substrate, and many improvements have been reported. For example, in PVA, a method for controlling the orientation of liquid crystal by saponification degree or chemical modification is known (see Patent Documents 4 to 6).
In many cases, the alignment substrate or alignment film cannot be used as it is for the final intended use due to the optical characteristics and the formation conditions of the birefringent layer. For example, the alignment substrate is colored or has non-uniform optical anisotropy. In such a case, it is necessary to transfer the formed birefringent layer to a substrate that does not hinder actual use.
Polyvinyl alcohol is known as an excellent alignment film material, but depending on the chemical structure and alignment conditions of the liquid crystal, it has strong adhesiveness with the formed birefringent layer (liquid crystal layer), making it difficult to transfer to other members. Sometimes there is a need for improvement.
Japanese Patent Laid-Open No. 08-152515 Japanese Patent Laid-Open No. 08-160429 Japanese Patent Laid-Open No. 06-242316 JP-A-62-183431 Japanese Patent Laid-Open No. 08-338913 JP 2002-062427 A

  The present invention provides a method for producing an optical film using the composition of polyvinyl alcohol (PVA), which solves the above-mentioned problems and does not change the alignment ability of liquid crystal and facilitates transfer of a birefringent layer, as an alignment film. .

  The first of the present invention is a step of forming an alignment film on a substrate, a step of rubbing the formed alignment film, a step of forming a birefringent layer on the alignment film subjected to the rubbing treatment, and the formed birefringence And a step of transferring the layer onto a base material different from the base material, wherein the alignment film is made of polyvinyl alcohol containing sodium polyacrylate. Method.

  Moreover, 2nd of this invention is 0.1-40 mass parts of content of sodium polyacrylate with respect to 100 mass parts of polyvinyl alcohol, The optical film as described in 1st of this invention characterized by the above-mentioned. Manufacturing method.

  3rd of this invention is a manufacturing method of the optical film as described in 1st of this invention characterized by the number average molecular weights of sodium polyacrylate being 1,000-500,000.

  4th of this invention is the manufacturing method of the optical film in any one of 1st-3rd of this invention characterized by the saponification degree of said polyvinyl alcohol being 98% or more.

  5th of this invention is a manufacturing method of the optical film in any one of 1st-4th of this invention characterized by the base material which forms the said alignment film being a plastic film.

  6th of this invention is a manufacturing method of the optical film in any one of the 1st-5th of this invention characterized by the said birefringent layer being formed from the material containing a liquid crystalline compound.

  7th of this invention is an optical film manufactured by the manufacturing method in any one of 1st-6th of this invention.

  An eighth aspect of the present invention is a liquid crystal display element using the optical film according to the seventh aspect of the present invention.

  According to the present invention, by using polyvinyl alcohol containing sodium polyacrylate as the alignment film, the transfer of the birefringent layer formed on the alignment film is facilitated, and the generation of defects (transfer defects and double defects) associated with the transfer is facilitated. Since the cracking of the refractive layer and the like can be suppressed, a product having an optically excellent quality can be obtained from the obtained optical film.

Hereinafter, the alignment film used in the present invention will be described.
The alignment film used in the present invention is polyvinyl alcohol (PVA) containing sodium polyacrylate.
The PVA used has a saponification degree of 98% or more, preferably 99.5% or more, more preferably 99.9% or more. When the degree of saponification of PVA is less than 98%, the abrasion resistance is poor in the rubbing treatment process, and the scraping of the PVA film is likely to occur, which contaminates the optical film manufacturing process.
Moreover, although there is no limitation in particular about the average degree of polymerization of PVA, Preferably it is 500-3500, More preferably, it is 1500-3500. Outside this range, the abrasion resistance at the time of rubbing is insufficient, the solubility at the time of preparing the solution is lowered, and the gel-like product remains, which is not preferable.

Next, the sodium polyacrylate used in the present invention will be described.
The sodium polyacrylate referred to in the present invention is not necessarily limited to a polymer consisting only of sodium acrylate, and even a copolymer with sodium maleate, sodium vinyl sulfonate or the like can be used if it is water-soluble. A homopolymer of sodium acrylate is preferred.
Sodium polyacrylate may be appropriately selected from commercially available products, such as Aquaric (registered trademark) L series (Nippon Shokubai Co., Ltd.), Jurimer AC series (Nippon Pure Chemicals Co., Ltd.). Can do.
Although there is no restriction | limiting in particular also about the number average molecular weight of sodium polyacrylate, Preferably it is 1,000-500,000, More preferably, it is 2,000-70,000. Outside this range, the effect of addition is not observed, and the solution viscosity when made into a solution becomes high and is difficult to handle.
The amount of sodium polyacrylate added is preferably 0.1 to 40 parts by mass, more preferably 0.2 to 20 parts by mass, and still more preferably 0.5 to 5 parts by mass per 100 parts by mass of PVA. Outside this range, the effect of addition is poor, and the resulting alignment film is not preferable because of its hygroscopicity.

An alignment film forming process will be described.
The alignment film can be formed by applying a solution in which PVA containing sodium polyacrylate is dissolved on a substrate and drying it as necessary.
The solvent for preparing the solution of the composition comprising PVA and sodium polyacrylate is not particularly limited as long as it can dissolve the composition. Usually, water is used, but a small amount of methanol, ethanol, isopropyl alcohol, etc. These lower alcohols or mixtures thereof may be used in combination. In addition, additives such as surfactants, antifoaming agents, and leveling agents that do not adversely affect the coating and the alignment of the liquid crystal may be added. Moreover, you may heat in order to accelerate | stimulate melt | dissolution.
As water used for dissolution, water containing a large amount of polyvalent metal ions is not preferable, ion-exchanged water is preferable, and water having an electric conductivity of 10 μS / cm or less is more preferable.
Water containing polyvalent metal ions may react with sodium polyacrylate to produce an insoluble compound.
In addition, the solution of the composition consisting of PVA and sodium polyacrylate is a method of preparing both individual solutions and mixing them so as to achieve the desired ratio, or a composition mixed in advance so as to obtain a desired ratio. It may be a method of dissolving, or a method of adding sodium polyacrylate to the PVA solution.

The coating method used to form the alignment film on the substrate is not particularly limited, and the coating method for the large-area alignment film is in particular a flexographic printing method using a soft resin plate, a dispenser method, a gravure coating method, a micro coating method. A gravure method, a screen printing method, a lip coating method, a die coating method, and the like can be given. Among these, a gravure coating method, a lip coating method and a die coating method are preferable.
The applied alignment film is dried if necessary. The drying temperature is usually limited by the heat resistance of PVA, but may be higher depending on the purpose. Generally, it is 90 to 180 ° C, preferably 100 to 160 ° C. The drying time is not particularly limited, but is usually 10 seconds to 60 minutes, preferably 1 minute to 30 minutes. The relative moving speed between the film to be dried and the drying apparatus is preferably 60 m / min to 1200 m / min in terms of relative wind speed.

  As the base material on which the alignment film is formed, films such as polyimide, polyphenylene sulfide, polyphenylene oxide, polyether ether ketone, polyether sulfone, polyethylene naphthalate, polyethylene terephthalate, polyarylate, triacetyl cellulose, poly (cycloolefin), etc. Can be illustrated. These base materials may be a uniaxially or biaxially stretched film or a film that has been subjected to a surface treatment such as easy adhesion or easy peelability.

Next, the alignment film is rubbed.
In the rubbing treatment, rubbing is performed at a predetermined arbitrary angle with respect to the long direction (hereinafter referred to as MD) of the long film, preferably at an angle of 0 to 45 degrees. This angle (rubbing angle) is an angle in the clockwise direction from the MD when the rubbing surface is viewed from above.
The rubbing process can be performed by any method. For example, referring to FIG. 1 as one of the methods, the long film (12) as the alignment substrate is placed on the stage (11) that conveys the long film (12) to the MD at an arbitrary angle with respect to the long film (12) and the MD. A rubbing roll (10) is disposed, and the rubbing roll (10) is rotated while conveying the long film (12), so that the surface of the film (12) is rubbed. The angle formed by the rubbing roll (10) and the moving direction of the stage (11) is a mechanism that can be freely adjusted.
A rubbing cloth manufactured using fibers made of cotton, polyester, rayon or the like is attached to the surface of the rubbing roll.

  In the rubbing treatment, it is important to rub the alignment film substrate surface in a certain direction in consideration of the hardness of the alignment film substrate surface. From this point of view, the rubbing pressure, the number of rotations of the rubbing roll, etc. are set appropriately. Usually, the alignment substrate is moved at a speed of 0.5 to 100 m / min, preferably 1 to 30 m / min, and the number of rotations of the rubbing roll is selected from the range of 1 to 1000, preferably 5 to 200 as the peripheral speed ratio. The The rubbing pressure may be such that the surface of the rubbing cloth is slightly in contact, and the pushing-in degree of the bristles of the rubbing cloth may be about 100 μm to 5000 μm, preferably about 100 μm to 2000 μm. If necessary, a cleaning treatment may be performed by spraying a pressurized gas on the rubbed surface, contacting with an adhesive roll, or the like.

In the present invention, the material for forming the birefringent layer is preferably a material containing a liquid crystalline compound (liquid crystalline composition), as long as the composition exhibits liquid crystallinity, and all the individual components constituting the liquid crystalline composition are included. It is not necessary to show liquid crystallinity.
As a component constituting the liquid crystalline composition, a low molecular liquid crystalline compound or a high molecular liquid crystalline compound is used regardless of the presence or absence of a reactive group, preferably a high molecular liquid crystalline compound, more preferably It is a polymer liquid crystalline compound having a reactive group.
The liquid crystal molecules may be rod-shaped or disk-shaped, but rod-shaped liquid crystal molecules are preferred.
In addition, other non-liquid crystalline polymer compounds that are miscible with the low-molecular liquid crystalline compounds and high-molecular liquid crystalline compounds, various activators and various additives such as surfactants, leveling agents, antifoaming agents, Antioxidants, dyes, pigments and the like can be added without departing from the scope of the present invention.
Examples of the low-molecular liquid crystalline compound include low-molecular liquid crystalline compounds having a polymerizable group such as a (meth) acryloyl group, a vinyloxy group, an oxiranyl group, and an oxetanyl group.

The polymer liquid crystalline compounds are roughly classified into main chain types and side chain types.
Examples of the main chain type polymer liquid crystalline compound include polyesters, polyester amides, polyamides, polycarbonates, etc., which exhibit liquid crystallinity, among others, from the viewpoint of ease of synthesis, orientation, glass transition point, etc. Liquid crystalline polyester is preferable, and main chain type liquid crystalline polyester having a cationic polymerizable group bonded thereto is particularly preferable.
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)). A main-chain liquid crystalline polyester containing at least two of the structural units (C) as essential units, and including a structural unit having a cationically polymerizable group at least at one end of the main chain. Main chain type liquid crystalline polyester. 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 has, as structural units, at least two of (A) aromatic diol units, (B) aromatic dicarboxylic acid units, and (C) aromatic hydroxycarboxylic acid units, preferably further Any structural unit may be used as long as it includes a structural unit having a cationically polymerizable group (hereinafter referred to as structural unit (D)) at least at one end of the main chain and exhibits thermotropic liquid crystallinity. Other structural units satisfy these conditions. As long as it does, it is not specifically limited.

  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 the amount is less than 20%, the temperature range in which the liquid crystallinity is exhibited may be extremely narrow. If the amount exceeds 99%, the number of units having a cationic polymerizable group is relatively small, and the orientation retention ability is reduced. The mechanical strength may not be improved.

  Next, the structural unit (D) having a cationic polymerizable group will be described. As the cationic polymerizable group, a functional group selected from the group consisting of an epoxy group, an oxetanyl group, and a vinyloxy group is preferable, and an oxetanyl group is particularly preferable. The compound for introducing the structural unit (D) is selected from an epoxy group, an oxetanyl group, and a vinyloxy group as an aromatic compound having a phenolic hydroxyl group or a carboxyl group, as shown in the following general formula (d). It is a compound to which a functional group having cationic polymerizability is bonded. Moreover, you may have a suitable spacer part between an aromatic ring and the said cation polymeric group.

However, -X in the formula, -X _1, -X _2, -Y, -Z represents any of the following groups each independently for each structural unit.
_{(1) -X, -X 1,} -X 2: -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,
(2) -Y: single _{bond, - (CH 2) n -} , - O -, - O- (CH 2) n -, - (CH 2) n -O -, - O- (CH 2) n - O -, - O-CO - , - CO-O -, - O-CO- (CH 2) n -, - CO-O- (CH 2) n -, - (CH 2) n -O-CO- , — (CH ₂ ) _n —CO—O—, —O— (CH ₂ ) _n —O—CO—, —O— (CH ₂ ) _n —CO—O—, —O—CO— (CH ₂ ) _{n -O -, - CO-O-} (CH 2) n -O -, - O-CO- (CH 2) n -O-CO -, - O-CO- (CH 2) n -CO-O- _{, -CO-O- (CH 2)} n -O-CO- or _{-CO-O- (CH 2) n} -CO-O-, ( where, n is an integer of 1-12.)
(3) Z:

  In the structural unit (D), the bonding position of the cationic polymerizable group or the substituent containing the cationic polymerizable group and the phenolic hydroxyl group or carboxylic acid group is 1 when the skeleton to which these groups are bonded is a benzene ring. From the viewpoint of liquid crystallinity, the 4-positional position is preferably a 2,6-positional position in the case of a naphthalene ring, and a 4,4′-positional position in the case of a biphenyl skeleton or a stilbene skeleton. More specifically, 4-vinyloxybenzoic acid, 4-vinyloxyphenol, 4-vinyloxyethoxybenzoic acid, 4-vinyloxyethoxyphenol, 4-glycidyloxybenzoic acid, 4-glycidyloxyphenol, 4- (oxetanyl) Methoxy) benzoic acid, 4- (oxetanylmethoxy) phenol, 4′-vinyloxy-4-biphenylcarboxylic acid, 4′-vinyloxy-4-hydroxybiphenyl, 4′-vinyloxyethoxy-4-biphenylcarboxylic acid, 4′- Vinyloxyethoxy-4-hydroxybiphenyl, 4′-glycidyloxy-4-biphenylcarboxylic acid, 4′-glycidyloxy-4-hydroxybiphenyl, 4′-oxetanylmethoxy-4-biphenylcarboxylic acid, 4′-oxetanylmethoxy- 4-hydroxybi Enyl, 6-vinyloxy-2-naphthalenecarboxylic acid, 6-vinyloxy-2-hydroxynaphthalene, 6-vinyloxyethoxy-2-naphthalenecarboxylic acid, 6-vinyloxyethoxy-2-hydroxynaphthalene, 6-glycidyloxy-2 -Naphthalenecarboxylic acid, 6-glycidyloxy-2-hydroxynaphthalene, 6-oxetanylmethoxy-2-naphthalenecarboxylic acid, 6-oxetanylmethoxy-2-hydroxynaphthalene, 4-vinyloxycinnamic acid, 4-vinyloxyethoxycinnamic acid, 4-glycidyloxycinnamic acid, 4-oxetanylmethoxycinnamic acid, 4'-vinyloxy-4-stilbenecarboxylic acid, 4'-vinyloxy-3'-methoxy-4-stilbenecarboxylic acid, 4'-vinyloxy-4-hydroxystilbene 4 '-Vinyloxyethoxy-4-stilbenecarboxylic acid, 4'-vinyloxyethoxy-3'-methoxy-4-stilbenecarboxylic acid, 4'-vinyloxyethoxy-4-hydroxystilbene, 4'-glycidyloxy-4- Stilbenecarboxylic acid, 4′-glycidyloxy-3′-methoxy-4-stilbenecarboxylic acid, 4′-glycidyloxy-4-hydroxystilbene, 4′-oxetanylmethoxy-4-stilbenecarboxylic acid, 4′-oxetanylmethoxy- 3′-methoxy-4-stilbene carboxylic acid, 4′-oxetanylmethoxy-4-hydroxystilbene and the like are preferable.

  The ratio of the structural unit (D) having a cationic polymerizable group to the total structural units constituting the main-chain liquid crystalline polyester is similarly expressed by the weight ratio in the composition charged with the structural unit (D) as carboxylic acid or phenol. When used, it is usually 1 to 60%, preferably 5 to 50%. If it is less than 1%, there is a possibility that the improvement of the orientation holding ability and the mechanical strength may not be obtained. If it exceeds 60%, the crystallinity is increased and the liquid crystal temperature range is narrowed. Is also not preferable.

  Each structural unit of (A) to (D) has one or two carboxyl groups or phenolic hydroxyl groups, but the carboxyl groups and phenolic hydroxyl groups of (A) to (D) are charged. It is desirable that the total number of equivalents of the respective functional groups be roughly aligned at this stage. That is, when the structural unit (D) is a unit having a free carboxyl group, (number of moles of (A) × 2) = (number of moles of (B) × 2) + number of moles of (D) ), When the structural unit (D) is a unit having a free phenolic hydroxyl group, (number of moles of (A) × 2) + (number of moles of (D)) = (number of moles of (B) × 2) It is desirable to generally satisfy the relationship In the case of a charged composition greatly deviating from this relational expression, carboxylic acid or phenol other than the unit involved in cationic polymerization, or a derivative thereof becomes the molecular end, and not only sufficient cationic polymerizability cannot be obtained, The presence of these acidic residues is not preferable because a polymerization reaction or a decomposition reaction may occur at a stage other than the desired stage in the process.

  The main chain type liquid crystalline polyester can contain structural units other than (A), (B), (C) and (D). Other structural units that can be contained are not particularly limited, and compounds (monomers) known in the art can be used. For example, naphthalene dicarboxylic acid, biphenyl dicarboxylic acid, aliphatic dicarboxylic acid, compounds in which halogen groups or alkyl groups are introduced into these compounds, biphenols, naphthalenediol, aliphatic diols, and compounds in which halogen groups or alkyl groups are introduced into these compounds Etc.

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 phenyl 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 0.03 to 0.50 dl / g in logarithmic viscosity η measured at 30 ° C. in a phenol / tetrachloroethane mixed solvent (mass ratio 60/40). Is 0.05 to 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, if 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 that the alignment and the crosslinking occur simultaneously to deteriorate the alignment.

  In the present invention, the molecular weight control of the main chain type liquid crystalline polyester is determined solely by the charged composition. Specifically, the main chain obtained by the relative content in the total charge composition of the monofunctional monomer that reacts in such a manner that both ends of the molecule are sealed, that is, the compound for introducing the structural unit (D) described above. The average degree of polymerization of the liquid crystal polyester (average number of bonds of the structural units (A) to (D)) 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. However, in the case of using deacetic acid polymerization under melting conditions, it is necessary to strictly control the reaction conditions because the monomer unit having a cationic polymerizable group may cause polymerization or decomposition reaction under the reaction conditions. In many cases, it is desirable to use a method such as using an appropriate protective group or reacting a compound having another functional group once and then introducing a cationically polymerizable group later. There is also. The crude main chain type liquid crystalline polyester obtained by the polymerization reaction may be purified by a method such as recrystallization or reprecipitation.

  The main-chain liquid crystalline polyester thus obtained is identified by the analytical means such as NMR (nuclear magnetic resonance method) at what ratio each monomer is present in the main-chain liquid crystalline polyester. can do. In particular, the average number of bonds of the main-chain liquid crystalline polyester can be calculated from the amount ratio of the cationic polymerizable group.

  It is also possible to mix other compounds with the main-chain liquid crystalline polyester containing the cationic polymerizable group as long as the scope of the present invention is not exceeded. For example, you may add the other high molecular compound miscible with the main chain type liquid crystalline polyester used for this invention, various low molecular weight compounds, etc. Such low molecular weight compounds may or may not have liquid crystallinity, and may or may not have a polymerizable group capable of reacting with a crosslinkable main chain liquid crystalline polyester. It is preferable to use a liquid crystalline compound having a polymerizable group, and examples thereof include the following.

Here, n represents an integer of 2 to 12, and -V- and -W each represents one of the following groups.
-V-: single bond, -O -, - O-C m H 2m -O- ( although, m is an integer from 2 to 12)
-W:

In addition, when the high molecular compound and low molecular compound to add are optically active, a chiral liquid crystal phase can be induced as a composition. Such a composition can be used for production of a film having a twisted nematic alignment structure or a cholesteric alignment structure.
Examples of the side chain polymer liquid crystalline compound include poly (meth) acrylate, polymalonate, polysiloxane, and the like. Among them, poly (meth) acrylate bonded with a reactive group represented by the following general formula (1) Is preferred.

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 crystalline compound 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 preferably represents a hydrocarbon group having 2, 3, 4, ⁶ , 8 or 18 carbon atoms.
Furthermore, the birefringence of the side chain type polymer liquid crystalline compound represented by the general formula (1) varies depending on the molar ratio of each component a to f and the orientation form, but the birefringence when nematic orientation is taken. The rate 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 crystalline compound can be obtained by an ordinary organic chemical synthesis method. The (meth) acrylic compound having an oxetanyl group can be easily obtained by a method similar to the synthesis of compounds corresponding to formulas (7), (8) and (9) described later.

  Said side chain type polymer liquid crystalline compound can be easily obtained by copolymerizing the (meth) acrylic group of each (meth) acrylic compound obtained by the above method corresponding to each component by radical polymerization or anionic polymerization. Can be synthesized. 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 polymer liquid crystalline compound 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 disclosed in various documents (C. Destrade et al., Mol. Crysr. 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.

In the present invention, the liquid crystalline composition preferably contains 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. .

  The liquid crystalline composition used in the present invention contains at least 10% by mass, preferably 30% by mass or more, more preferably 50% by mass or more of the low molecular liquid crystalline compound or the high molecular liquid crystalline compound, and has liquid crystallinity. It is the composition shown. When the content of the low-molecular liquid crystalline compound or the high-molecular liquid crystalline compound is less than 10% by mass, the concentration of the compound exhibiting liquid crystallinity in the composition is low, and the composition may not exhibit liquid crystallinity. Absent.

As described above, the liquid crystalline composition of the present invention may contain various compounds that can be mixed without impairing liquid crystallinity in addition to the low molecular liquid crystalline compound or the high molecular liquid crystalline compound. Examples of the 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 epoxy 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, if a surfactant, antifoaming agent, leveling agent, etc., as well as a compound having a reactive functional group or a low molecular or high molecular liquid crystal is used as described above, a reaction start suitable for each functional group is started. You may add an agent, an activator, a sensitizer, etc. within the range which does not deviate from the objective of this 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.

  As said polymeric compound, the compound which can improve the workability and adhesiveness in the next processing process of the liquid crystal film obtained by a case is preferable, and the (meth) acrylates which have an oxetanyl group are especially preferable. Examples of these (meth) acrylates include compounds represented by general formulas (7), (8) and (9).

In the above formula (7), formula (8) and formula (9), each R ¹ independently represents hydrogen or a methyl group, each R ² independently represents hydrogen, a methyl group or an ethyl group, L ¹ each independently represents a single bond, —O—, —O—CO— or —CO—O—, m is each independently an integer of 1 to 10, and n is each independently Represents an integer from 0 to 10.

などが特に好ましい。 Various specific compounds corresponding to these formulas (7), (8) and (9) can be mentioned, but they do not necessarily have liquid crystallinity.
More specifically,

Etc. are particularly preferred.

The method for synthesizing these (meth) acrylates having an oxetanyl group is not particularly limited, and can be synthesized by applying a method used in ordinary organic chemistry synthesis methods.
For example, by combining a site with an oxetanyl group and a site with a (meth) acryloyl group by means such as Williamson's ether synthesis or ester synthesis using a condensing agent, the oxetanyl group and the (meth) acryloyl group are completely A (meth) acrylate having an oxetanyl group having two different reactive groups 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 detailed in the synthesis of the compound represented by the above general formula (1).

Examples of the reaction initiator include organic peroxides used in general radical polymerization and various photopolymerization initiators.
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.

Examples of the photoradical initiator include commercially available benzoin ethers, acylphosphine oxides, triazine derivatives, and imidazole derivatives used for general ultraviolet (UV) curable paints, UV adhesives, negative resists, 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 ⁻ , Ar ₂ I ⁺ PF ₆ ⁻ (wherein Ar represents a phenyl group or a substituted phenyl group), and the like. 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.

Although the formation method of a liquid crystalline composition (birefringence) layer is demonstrated below, as a formation method of a liquid crystalline composition layer, it is not limited to these.
First, the liquid crystalline composition of the present invention is developed on the alignment film substrate.
As a method for forming a liquid crystalline composition layer by spreading the liquid crystalline composition on the alignment film substrate, a method in which the liquid crystalline composition is directly applied on the alignment substrate in a molten state, or a solution of the liquid crystalline composition is used. The method of drying a coating film and distilling a solvent after apply | coating on an orientation board | substrate is mentioned.
The solvent used for preparing the solution is not particularly limited as long as it is a solvent that can dissolve various compounds used in the liquid crystal composition of the present invention and can be distilled off under appropriate conditions. Generally, acetone, methyl ethyl ketone, isophorone, Ketones such as cyclohexanone, butoxyethyl alcohol, hexyloxyethyl alcohol, ether alcohols such as methoxy-2-propanol and benzyloxyethanol, glycol ethers such as ethylene glycol dimethyl ether and diethylene glycol dimethyl ether, ethyl acetate, ethyl lactate, γ- Esters such as butyrolactone, phenols such as phenol and chlorophenol, amides such as N, N-dimethylformamide, N, N-dimethylacetamide and N-methylpyrrolidone, chloro Lum, tetrachloroethane, halogenated such or a mixture of these systems, such as dichlorobenzene are preferably used. Moreover, 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. Examples thereof include a flexographic printing method, an offset printing method, a dispenser method, a gravure coating method, a micro gravure method, a screen printing method, a lip coating method, and a die coating method. 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 application of the birefringent layer to be obtained, etc., but it is 0.1 to 20 μm, preferably 0.3 to 30 mm after drying. 10 μm. Alternatively, since the liquid crystalline composition of the present invention exhibits refractive index anisotropy by being oriented, it is not always sufficient to simply define the coating film thickness only by the film thickness. In some cases, it is preferable to specify the value (= refractive index anisotropy × film thickness: Δn × d). The retardation value at that time is 10 to 1000 nm, preferably 20 to 800 nm. If the film thickness and / or retardation value is outside this range, the desired effect is not observed, and the orientation is insufficient.

  Subsequently, after the liquid crystal composition (birefringence) layer formed on the alignment film substrate is aligned with a liquid crystal by a method such as heat treatment, a reactive group is reacted by light irradiation and / or heat treatment as necessary. The orientation is fixed. 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 alignment of the liquid crystalline composition layer by the above method, when a liquid crystalline composition containing a reactive group is used, the liquid crystalline composition is kept in the composition while maintaining the liquid crystal alignment state. The function of the reaction initiator contained is expressed and the reactive group is reacted to fix the orientation or improve the mechanical strength.

When the reaction initiator expresses the function of the initiator by light irradiation, the light irradiation method includes a metal halide lamp having a spectrum in the absorption wavelength region of the reaction initiator used, a high-pressure mercury lamp, a low-pressure mercury lamp, a xenon lamp, Irradiates light from a light source such as an arc lamp or laser to activate the reaction initiator. 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 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 during light irradiation is preferably in the 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 crystal material. preferable.
Thus, a birefringent layer is formed on the alignment film substrate.

Next, the transfer process of the birefringent layer will be described.
As an alignment film substrate, it is not optically isotropic, or the resulting birefringent layer is finally opaque in the intended use wavelength region, or the film thickness of the alignment film substrate is too thick, which hinders actual use. When there is a problem such as occurring, a wavelength different from the alignment film substrate from the form formed on the alignment film substrate, for example, the optically isotropic or the obtained birefringent layer is finally intended wavelength In the region, the film is transferred to a film that is temporarily supported until a transparent film or a birefringent layer is bonded to a liquid crystal cell or the like.
As a transfer method, a known method can be adopted. For example, as described in JP-A-4-57017 and JP-A-5-333313, a birefringent layer is required after laminating a substrate different from the alignment film substrate via an adhesive or an adhesive. A method of transferring only the birefringent layer by subjecting the pressure-sensitive adhesive or adhesive to curing treatment and peeling the alignment film substrate from the laminate can be exemplified.

Examples of the substrate different from the alignment film substrate include triacetyl cellulose films such as Fujitac (product of Fuji Photo Film) and Konicatak (product of Konica Minolta Opto), TPX film (product of Mitsui Chemicals), Arton film ( Transparent films such as JSR products), ZEONEX films (Nippon ZEON products), acrylprene films (Mitsubishi Rayon products), and the like. Moreover, temporary support films, such as a polyethylene terephthalate film etc. which performed the silicone process or provided the easy peeling layer on the surface etc. are mentioned. Furthermore, if necessary, a film provided with a retardation function by stretching or the like, various retardation films including a liquid crystal alignment layer, a polarizing element, a polarizing plate, various glasses, and the like can be exemplified.
Examples of the film provided with the retardation function include those obtained by uniaxially stretching or biaxially stretching a polymer film, and various retardation films including a liquid crystal alignment layer include coating / alignment films of liquid crystalline polymers. Can be mentioned.

  The polymer film that performs uniaxial stretching or biaxial stretching preferably has a smooth plane and high transmittance, and examples thereof include films and sheets made of organic polymer materials, such as polyvinyl alcohol and polyimide. , Polyester polymers such as polyphenylene oxide, polyether ketone, polyether ether ketone, polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, polycarbonate polymers, acrylic polymers such as polymethyl methacrylate, etc. And a film made of a transparent polymer. Also, styrene polymers such as polystyrene, acrylonitrile / styrene copolymer, olefin polymers such as polyethylene, polypropylene, polycycloolefin, ethylene / propylene copolymer, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide. A film made of a transparent polymer such as Furthermore, imide polymers, sulfone polymers, polyether sulfone polymers, polyether ether ketone polymers, polyphenylene sulfide polymers, vinyl alcohol polymers, vinylidene chloride polymers, vinyl butyral polymers, arylate polymers, polyoxymethylene polymers Examples thereof include a film made of a transparent polymer such as a polymer, an epoxy-based polymer, and a blend of the above polymers. Among these, plastic films such as triacetyl cellulose, polycarbonate, and polycycloolefin that are used as optical films are used. Examples of the organic polymer film include ZEONOR (trade name, manufactured by ZEON CORPORATION), ZEONEX (trade name, manufactured by ZEON CORPORATION), Arton (trade name, manufactured by JSR Corporation), etc. A plastic film made of a polymer material having a cyclic structure is preferably used. A retardation film produced by a method of uniaxially or biaxially stretching the above-described film, a method of reducing the retardation in the stretching direction by a heat shrink film as disclosed in JP-A-5-157911, and The polymer film described in 2001-343529 (WO01 / 37007) has optically excellent characteristics. Examples of the polymer material include a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain. For example, a resin composition having an alternating copolymer composed of isobutene and N-methylenemaleimide and an acrylonitrile / styrene copolymer can be mentioned. The polymer film may be, for example, an extruded product of the resin composition.

  As a liquid crystal polymer coating / alignment film, a liquid crystal polymer that exhibits uniform and monodomain nematic alignment and can easily fix the alignment state on a substrate or a substrate coated with an alignment film. By heat-treating to form a uniform, monodomain nematic structure and then cooling, it is manufactured by fixing without impairing the alignment in the liquid crystal state. The liquid crystal polymer can also be used as a liquid crystal composition by blending a photopolymerizable liquid crystal compound. Since the liquid crystal polymer containing the photopolymerizable liquid crystal compound can form a film on a substrate or a substrate coated with an alignment film having nematic alignment ability, the glass transition point (Tg) of the liquid crystal film can be designed to be low. . In order to improve the durability that can be used for applications such as a liquid crystal display, it is preferable to use a nematic alignment liquid crystalline composition containing a photopolymerizable liquid crystal compound for the film made of these liquid crystal compounds. The nematic alignment liquid crystalline composition is irradiated with light such as ultraviolet rays after being aligned.

  The pressure-sensitive adhesive or adhesive used for transfer is not particularly limited as long as it is of optical grade. For example, acrylic, epoxy resin, ethylene-vinyl acetate copolymer, rubber, urethane, and mixtures thereof And various reactive types such as a thermosetting type and / or a photo-curing type and an electron beam curable type. The reaction (curing) conditions for the reactive ones vary depending on the components constituting the adhesive / adhesive, the viscosity, the reaction temperature, and the like. Therefore, the conditions suitable for each may be selected. For example, in the case of the photo-curing type, the same light source as in the case of fixing the liquid crystal composition layer with light described above may be used and the irradiation amount may be the same. , Preferably 20 kV to 100 kV.

Thus, the birefringent layer is transferred from the alignment film substrate to another substrate to obtain an optical film.
The optical film of the present invention has various uses depending on its orientation structure, and is particularly preferably used as a viewing angle improving film for liquid crystal display elements.
Although there is no restriction | limiting in particular as a liquid crystal display element, Various liquid crystal display elements of a transmissive type, a reflective type, and a semi-transmissive type can be mentioned. Examples of modes by liquid crystal alignment in a liquid crystal cell include TN type, STN type, VA (vertical alignment) type, MVA (multi-domain vertical alignment) type, OCB (optically compensated bend) type, ECB (electrically concentrated bend) type, and ECB (electrically concentrated bend) type. Type, HAN (hybrid-aligned nematic) type, IPS (in-plane switching) type, and the like. With respect to the liquid crystal alignment, it may have a single directionality within the plane of the cell, or may be used for a liquid crystal display element or the like in which the alignment is divided. Further, in terms of a method of applying a voltage to the liquid crystal cell, for example, a liquid crystal display element driven by a passive method using an ITO electrode or the like, an active method using a TFT (thin film transistor) electrode, a TFD (thin film diode) electrode, or the like. be able to.

EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to this.
The measurement methods used are described below.
(1) Measurement of molecular weight A compound is dissolved in tetrahydrofuran, and TS is used with Tosoh 8020GPC system.
K-GEL SuperH1000, SuperH2000, SuperH3000, S
Upper H4000 was connected in series and measured using tetrahydrofuran as the eluent. Polystyrene standards were used for molecular weight calibration.
(2) Measurement of solid content concentration The solid content concentration was measured from the decrease in mass before and after measuring the obtained PVA composition solution on an aluminum tray using an oven HT310S manufactured by ETAC and drying in air at 107 ° C for 3 hours. did.
(3) Microscope observation The orientation state of the birefringent layer was observed with an Olympus BH2 polarizing microscope. In addition, a part was also observed visually.
(4) Peel strength measurement method (evaluation of transferability)
The test was carried out with a 25 mm wide specimen in accordance with the JIS K6854 180 degree peeling method test. The measurement used Toyo Seiki Seisakusho Strograph E-L.

[Reference Example 1]
In a 500 L stainless steel tank equipped with a reflux condenser and a stirrer, PVA (manufactured by Nippon Vinegar Poval Co., Ltd., trade name AT, average saponification degree 99.94%, average polymerization degree 1700 (PVA 53%, moisture 47 %) 30.19 kg of deionized water (electric conductivity value: 1 μS / cm or less) was added, heated at 95 ° C. for 3 hours, dissolved by stirring, and then cooled to 70 ° C. Next, as sodium polyacrylate Aqualic L series YS100 (45% aqueous solution, number average molecular weight 5500, Nippon Shokubai Co., Ltd.) 0.91 kg was gradually added to obtain a homogeneous solution.
It cooled to 30 degreeC vicinity, and extracted, filtering the PVA composition solution from the said tank. Filtration is performed using a cartridge filter (ADVANTEC TCP-JX-S1FE (1 μm)) capable of collecting particles having an average particle diameter of 1 μm at a filtration rate of 20 kg / 2 minutes, and 270 kg of a solution having a solid concentration of about 5% by mass. Got. In addition, the ratio of sodium polyacrylate / PVA is 2.6 / 100 (mass ratio).

[Reference Example 2]
In the same manner as in Reference Example 1, a PVA composition solution was prepared. However, PVA is a product name of VC-20DH (average saponification degree 99.92%, average degree of polymerization 2000) manufactured by Nippon Vinegar Poval Co., Ltd., and sodium polyacrylate is Aqualic L series DL- 453 (number average molecular weight 50000, Nippon Shokubai Co., Ltd.) was used. The ratio of sodium polyacrylate / PVA is 2.6 / 100 (mass ratio).

[Reference Example 3]
In the same manner as in Reference Example 1, PVA (manufactured by Nippon Vinegar Poval Co., Ltd., trade name AT, average degree of saponification 99.94%, average degree of polymerization 1700 (PVA 53%, moisture 47%)) was used. Thus, a PVA composition solution was obtained. The ratio of sodium polyacrylate / PVA is 1.5 / 100 (mass ratio).

[Reference Example 4]
In the same manner as in Reference Example 1, a PVA composition solution was obtained using PVA (manufactured by Kuraray Co., Ltd., trade name PVA117, average degree of saponification 98.0%, average degree of polymerization 1700). The ratio of sodium polyacrylate / PVA is 2.6 / 100 (mass ratio).

[Reference Example 5]
In the same manner as in Reference Example 1, PVA (Nippon Vinegar Poval Co., Ltd., trade name AT, average saponification degree 99.94%, average polymerization degree 1700 (PVA 53%, moisture 47%)) was used. A PVA composition solution was obtained. The ratio of sodium polyacrylate / PVA is 1.0 / 100 (mass ratio).

[Reference Example 6]
In the same manner as in Reference Example 1, PVA (manufactured by Nippon Vinegar Bipovar Co., Ltd., trade name AT, average degree of saponification 99.94%, average degree of polymerization 1700 (PVA 53%, moisture 47%)) was used. A composition solution was obtained. The ratio of sodium polyacrylate / PVA is 0.5 / 100 (mass ratio).

[Reference Example 7]
In a 500 L stainless steel tank equipped with a reflux condenser and a stirrer, PVA (manufactured by Nihon Vinegar Bipoval Co., Ltd., trade name AT, average saponification degree 99.94%, average polymerization degree 1700 (PVA 53%, moisture 47%) ) 30.19 kg of deionized water 369.81 kg (electrical conductivity value: 1 μS / cm or less) was added, heated at 95 ° C. for 3 hours, dissolved by stirring, and then gradually cooled to room temperature.
It cooled to 30 degreeC vicinity, and extracted, filtering the PVA solution from the said tank. Filtration is performed using a cartridge filter (ADVANTEC TCP-JX-S1FE (1 μm)) capable of collecting particles having an average particle diameter of 1 μm at a filtration rate of 20 kg / 2 minutes, and 360 kg of a solution having a PVA concentration of about 4% by mass is obtained. Obtained.

[Reference Example 8]
A liquid crystal composition solution used for production of an optical film was prepared as follows.
A liquid crystalline polymer represented by the following formula (10) 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.
After 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, reagent) was added in the dark, and then a pore diameter of 0.45 μm was added. A liquid crystal composition solution was prepared by filtration through a polytetrafluoroethylene filter.
In addition, although following formula (10) is displayed with the form of a block copolymer, it represents the monomer composition ratio (mol ratio) at the time of superposition | polymerization.

[Examples 1 to 6 and Comparative Example 1]
(Formation of alignment film)
Obtained in Reference Examples 1 to 7 on a polyethylene naphthalate film (PEN: Teijin DuPont Films Co., Ltd., trade name Q51) having a width of 650 mm and a length of 1000 m so that the dry film thickness is about 1 μm by a gravure coater at room temperature. The obtained PVA composition solution or PVA solution was continuously applied. The coating film was continuously dried 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)
With the apparatus shown in FIG. 1, a 150 mm diameter rubbing roll with a rubbing cloth wrapped around the alignment film surface is conveyed with respect to the MD of the film while conveying the long film with the alignment film obtained above at a speed of 20 m / min. The rubbing cloth was continuously rubbed by rotating at 1500 rpm (peripheral speed ratio 35) with the pushing of the bristles of the rubbing cloth set to 45 μm and rotating at 1500 rpm, and wound on a roll.

(Manufacture of optical film)
The liquid crystalline composition solution obtained in Reference Example 8 was applied on the rubbing-treated long film using a roll coater so that the birefringent layer thickness after orientation / curing was 1 μm, and then at 60 ° C. And dried at 140 ° C. for 2 minutes to orient the liquid crystalline composition layer, and then an ultraviolet ray irradiation apparatus equipped with a high-pressure mercury lamp maintained at an ambient temperature of 70 ° C. is applied with an ultraviolet ray of 300 mJ / cm ² . The alignment was fixed by irradiation with light and cooled to room temperature to obtain an alignment substrate having a birefringent layer.

Since the PEN film as the base material is optically anisotropic, the birefringent layer was transferred onto the triacetyl cellulose film with an acrylic adhesive as follows.
On the birefringent layer of the alignment film substrate having the obtained birefringent layer, a commercially available UV curable adhesive (UV-3400, manufactured by Toagosei Co., Ltd.) was applied as an adhesive layer to a thickness of 5 μm. After laminating with a triacetyl cellulose (TAC) film and irradiating ultraviolet rays from the TAC film side to cure the adhesive layer, the PEN film and the alignment film layer were peeled off to obtain an optical film. About the obtained optical film, orientation, a fault, etc. were test | inspected by the microscope and visual observation. Moreover, the peelability at the time of peeling a birefringent layer, a PEN film, and an alignment film layer was observed, and the peel strength was also measured. The results are shown in Table 1.
As is apparent from Table 1, the peel strength can be reduced without changing the orientation of the liquid crystal layer, the occurrence of defects, etc., and transfer to a substrate different from the alignment substrate can be easily performed.

It is a top view of the apparatus which rubs a long film-like orientation board | substrate at arbitrary angles with respect to the MD.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Rubbing roll 11 Stage 12 which conveys alignment board Long film as alignment board

Claims (8)

  The step of forming an alignment film on a substrate, the step of rubbing the formed alignment film, the step of forming a birefringent layer on the alignment film that has been rubbed, and the formed birefringent layer as the substrate A method for producing an optical film comprising the steps of: transferring to a different substrate, wherein the alignment film comprises polyvinyl alcohol containing sodium polyacrylate.   Content of sodium polyacrylate is 0.1-40 mass parts with respect to 100 mass parts of polyvinyl alcohol, The manufacturing method of the optical film of Claim 1 characterized by the above-mentioned.   The number average molecular weight of sodium polyacrylate is 1,000-500,000, The manufacturing method of the optical film of Claim 1 characterized by the above-mentioned.   The method for producing an optical film according to claim 1, wherein the degree of saponification of the polyvinyl alcohol is 98% or more.   The method for producing an optical film according to claim 1, wherein the base material on which the alignment film is formed is a plastic film.   The method for producing an optical film according to claim 1, wherein the birefringent layer is formed of a material containing a liquid crystal compound.   The optical film manufactured by the manufacturing method in any one of Claims 1-6.   A liquid crystal display device using the optical film according to claim 7.

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