JP2008009346A - Retardation film and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a retardation film in which a transparent substrate comprising a cycloolefin-based resin is used, and which has properties as a positive C plate and excels in adhesion between the transparent substrate and another layer. <P>SOLUTION: The retardation film comprises the transparent substrate comprising the cycloolefin-based resin and an adhesive retardation layer formed on the transparent substrate, containing a polymer of a polymerizable monomer and a liquid crystal material having homeotropic alignment property, and satisfying the relationship of nx=ny<zy among refractive indexes nx and ny in an arbitrary x direction and y direction perpendicular to each other in an in-plane direction and a refractive index nz in a thickness direction, wherein value (N/M) given by diving the number N of carbons constituting the polymerizable monomer by the number M of elements constituting the polymerizable monomer except carbon and hydrogen is ≥3. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a retardation film used for a liquid crystal display device and the like, and a method for producing the same, and more particularly relates to a retardation film using a transparent substrate made of a cycloolefin resin and a method for producing the same. Is.

  The liquid crystal display device has features such as power saving, light weight, thinness, and the like, and has rapidly spread in recent years in place of the conventional CRT display. As a general liquid crystal display device, as shown in FIG. 3, a liquid crystal display device having an incident-side polarizing plate 102 </ b> A, an emitting-side polarizing plate 102 </ b> B, and a liquid crystal cell 104 can be exemplified. The polarizing plates 102A and 102B are configured to selectively transmit only linearly polarized light (schematically illustrated by arrows in the figure) having a vibration surface in a predetermined vibration direction. They are arranged to face each other in a crossed Nicol state so as to have a right angle relationship with each other. The liquid crystal cell 104 includes a large number of cells corresponding to the pixels, and is disposed between the polarizing plates 102A and 102B.

  Such a liquid crystal display device is known to use various driving methods depending on the arrangement form of the liquid crystal material used in the liquid crystal cell. The main liquid crystal display devices that are widely used today are TN, It is classified into STN, MVA, IPS and OCB. In particular, today, those having the MVA and IPS drive systems have come into widespread use.

  On the other hand, the liquid crystal display device has a problem of viewing angle dependency due to the refractive index anisotropy of the liquid crystal cell as a specific problem. This problem of viewing angle dependency is a problem in which the color and contrast of a visually recognized image change between when the liquid crystal display device is viewed from the front and when viewed from an oblique direction. Such a problem of viewing angle characteristics has become more serious as the liquid crystal display device has recently been enlarged.

In order to improve such a problem of viewing angle dependency, various techniques have been developed so far, and a representative method is a method using a retardation film. In the method using such a retardation film, the retardation film 30 having predetermined optical characteristics is disposed between the liquid crystal cell 104 and the polarizing plate 102B as shown in FIG. It is a way to improve the problem. Since this method can improve the viewing angle dependency only by incorporating the retardation film 30 in the liquid crystal display device, it is widely used as a method for easily obtaining a liquid crystal display device having excellent viewing angle characteristics. Has come to be.
Here, as the retardation film, for example, a film having a structure in which a retardation layer containing a regularly arranged liquid crystal material is formed on a transparent substrate or a film made of a stretched film is generally known. It has been.
Among them, in an IPS (In-Plane Switching) type liquid crystal display device, a retardation film having a retardation layer having properties as a positive C plate is obtained by homeotropic alignment of a liquid crystal material. .

  Conventionally, a film made of cellulose triacetate has been widely used as a transparent substrate constituting such a retardation film. Cellulose triacetate is a material with low birefringence and excellent optical isotropy, so it is easy to design optical properties, and because it uses cellulose, which is a natural material, as a raw material, it is industrially inexpensive. The main reason is that it is highly useful in that it is available in However, the retardation film used in the liquid crystal display device as described above is required to have a desired birefringence according to the display method of various liquid crystal display devices, and the cellulose triacetate has heat resistance. There is a problem that it is low and has high water absorption, so that it is easily deformed by heat and moisture. There is also a problem that the birefringence variation due to moisture absorption is large.

  In order to solve such a problem, Patent Document 1 and Patent Document 2 disclose a retardation film using a cycloolefin resin instead of the cellulose triacetate. The cycloolefin-based resin has the advantage that the glass transition point and the moisture absorption rate can be controlled in a preferable range by molecular design, and good heat resistance and appropriate water absorption can be realized. Therefore, by using a cycloolefin resin, it is possible to obtain a retardation film with little optical property change and dimensional change due to water absorption.

Taking advantage of such a cycloolefin resin, Patent Document 3 discloses that a retardation layer in which a liquid crystal material is homeotropically aligned is formed on a substrate made of a cycloolefin resin, and is suitable for an IPS liquid crystal display device. A retardation film having properties as a positive C plate used in the above is disclosed. Such a retardation film has an advantage that, by using a transparent substrate made of a cycloolefin-based resin, moisture absorption deformation or the like that has been a problem when a film made of triacetyl cellulose has been conventionally used can be improved. .
However, since the cycloolefin-based resin generally has low adhesion to the liquid crystal material used for the retardation layer, the retardation film described in Patent Document 3 includes a retardation layer and a transparent substrate. There was a problem that the adhesion of the material was low and the practicality was poor.
In this regard, Patent Document 4 discloses the idea of using a pressure-sensitive adhesive made of an acrylic resin or the like to bond a homeotropically aligned retardation layer and a transparent substrate made of a cycloolefin-based resin, Even when such a pressure-sensitive adhesive is used, it has been difficult to achieve sufficient adhesion between the retardation layer and the transparent substrate.

  For these reasons, a retardation film using a cycloolefin-based resin has the above-described advantages, but has a problem of lack of practicality.

Japanese Patent Laying-Open No. 2005-8698 Japanese Patent Application Laid-Open No. 2004-309979 JP 2002-174725 A JP 2003-121853 A

  The present invention has been made in view of such problems, and is a retardation film having a property as a positive C plate using a transparent substrate made of a cycloolefin-based resin. The main object of the present invention is to provide a retardation film having excellent adhesion to the layer.

  In order to solve the above problems, the present invention includes a transparent substrate made of a cycloolefin-based resin, a polymer of a polymerizable monomer and a liquid crystal material having homeotropic alignment formed so as to be in contact with the transparent substrate. An adhesive retardation layer in which a relationship of nx = ny <nz is established between the refractive indices nx and ny in any x direction and y direction perpendicular to each other in the in-plane direction and the refractive index nz in the thickness direction; Wherein the polymerizable monomer is at least one polymerizable selected from the group consisting of the following formulas (I), (II), (III), (IV), and (V) A value (N / M) obtained by dividing the carbon number N constituting the polymerizable monomer by the number M of elements other than carbon and hydrogen constituting the polymerizable monomer is 3 or more. is there To provide a phase difference film characterized and.

Here, in the above formula, R ¹ , R ² and R ³ represent a methyl group or hydrogen. R ⁴ represents hydrogen, a methyl group or an ethyl group.

According to the present invention, at least one polymerizable functional group selected from the group consisting of the above formulas (I), (II), (III), (IV), and (V) is provided on the adhesive retardation layer. (N / M) (hereinafter simply referred to as “carbon content ratio”), and the number N of carbons constituting the polymerizable monomer and the number M of elements other than carbon and hydrogen constituting the polymerizable monomer. ) Is improved to improve the adhesion between the adhesive retardation layer and the transparent substrate made of the cycloolefin resin. Can do. For this reason, according to the present invention, a retardation film using a transparent substrate made of a cycloolefin-based resin is obtained, and a retardation film having excellent adhesion between the adhesive retardation layer and the transparent substrate is obtained. Can do.
Further, there is a relationship of nx = ny <nz between the refractive indexes nx and ny in any x direction and y direction in which the adhesive retardation layer is orthogonal to each other in the in-plane direction and the refractive index nz in the thickness direction. By being established, the retardation film of the present invention can be imparted with a property as a positive C plate.
Therefore, according to the present invention, a retardation film having properties as a positive C plate using a transparent substrate made of a cycloolefin resin, comprising an adhesive retardation layer and a transparent substrate, A retardation film having excellent adhesion can be obtained.

  In addition, the retardation film of the present invention has an adhesion function in which the adhesive retardation layer improves adhesion to the transparent substrate, and a retardation imparting function that imparts retardation to the retardation film of the present invention. Therefore, for example, it has an advantage that the manufacturing process can be simplified as compared with a retardation film separately having the layer having the adhesion function and the layer having the retardation imparting function.

  In the present invention, the adhesive retardation layer preferably contains a surfactant. As a result, the homeotropic alignment of the liquid crystal material in the adhesive phase difference layer can be made more regular, and therefore the adhesive phase difference layer in the present invention has excellent retardation properties. It is because it can be made.

  In order to solve the above problems, the present invention uses a transparent substrate made of a cycloolefin-based resin, and forms an adhesive retardation layer in which at least a polymerizable monomer and a liquid crystal material having homeotropic orientation are dissolved in a solvent. An adhesive phase difference layer forming layer forming step for forming an adhesive phase difference layer forming layer by coating the coating liquid so as to be in contact with the transparent substrate; and the adhesive phase difference layer forming step. A curing treatment step of forming an adhesive retardation layer by polymerizing a polymerizable monomer contained in the layer, and on the transparent substrate, any x direction and y direction perpendicular to each other in the in-plane direction For producing a retardation film in which an adhesive retardation layer is formed in which a relationship of nx = ny <nz is established between the refractive indexes nx and ny of the film and the refractive index nz in the thickness direction The polymerizable monomer has at least one polymerizable functional group selected from the group consisting of the following formulas (I), (II), (III), (IV), and (V) And the value (N / M) obtained by dividing the number N of carbon atoms constituting the polymerizable monomer by the number M of elements other than carbon and hydrogen constituting the polymerizable monomer is 3 or more. A method for producing a retardation film is provided.

Here, in the above formula, R ¹ , R ² and R ³ represent a methyl group or hydrogen. R ⁴ represents hydrogen, a methyl group, or an ethyl group.

According to the present invention, at least one selected from the group consisting of the above formulas (I), (II), (III), (IV), and (V) is used as the adhesive retardation layer forming coating solution. In the retardation film produced according to the present invention, the adhesive phase-difference layer is produced by including a polymer of a polymerizable monomer having one polymerizable functional group and a carbon content ratio of 3 or more, Adhesion with a transparent substrate made of a cycloolefin resin can be improved. For this reason, according to the present invention, a retardation film using a transparent substrate made of a cycloolefin-based resin is manufactured, and the retardation film having excellent adhesion between the adhesive retardation layer and the transparent substrate is produced. be able to.
Further, the retardation film produced according to the present invention has a refractive index nx and ny in any x direction and y direction orthogonal to each other in the in-plane direction, and a refractive index nz in the thickness direction, nx = ny < By having an adhesive retardation layer that satisfies the nz relationship, a retardation film having properties as a positive C plate can be produced according to the present invention.
Therefore, according to the present invention, a retardation film having properties as a positive C plate using a transparent substrate made of a cycloolefin resin, comprising an adhesive retardation layer and a transparent substrate, A retardation film having excellent adhesion can be produced.

  The present invention is a retardation film having a property as a positive C plate using a transparent substrate made of a cycloolefin-based resin, and having excellent adhesion between an adhesive retardation layer and a transparent substrate. There is an effect that a film can be obtained.

  Hereinafter, the retardation film of the present invention and the method for producing the retardation film will be described in order.

A. Retardation Film First, the retardation film of the present invention will be described. The retardation film of the present invention contains a transparent substrate made of a cycloolefin-based resin, a polymer of a polymerizable monomer formed on and in contact with the transparent substrate, and a liquid crystal material having homeotropic orientation, Having an adhesive retardation layer in which a relationship of nx = ny <nz is established between any refractive index nx and ny in the x direction and y direction orthogonal to each other in the inner direction and the refractive index nz in the thickness direction The polymerizable monomer has at least one polymerizable functional group selected from the group consisting of the formulas (I), (II), (III), (IV), and (V) And the value (N / M) obtained by dividing the number N of carbon atoms constituting the polymerizable monomer by the number M of elements other than carbon and hydrogen constituting the polymerizable monomer is 3 or more. To do It is.

Such a retardation film of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view showing an example of the retardation film of the present invention. As illustrated in FIG. 1, a retardation film 10 of the present invention is formed on a transparent substrate 1 made of a cycloolefin resin and the transparent substrate 1, and any x direction and y direction perpendicular to each other in the in-plane direction. The adhesive phase difference layer 2 in which the relationship of nx = ny <nz is established between the refractive indexes nx and ny of the above and the refractive index nz in the thickness direction.
In such an example, the retardation film 10 of the present invention is applied to the adhesive retardation layer 2 from the group consisting of the above formulas (I), (II), (III), (IV), and (V). A polymer of a polymerizable monomer having at least one polymerizable functional group selected and having a carbon content ratio of 3 or more and a liquid crystal material having homeotropic alignment are included. is there.
In the retardation film 10 of the present invention, the liquid crystal material contained in the adhesive retardation layer 2 has a homeotropic alignment property that has a property of forming a homeotropic alignment without using a vertical alignment film. Therefore, the liquid crystal material contained in the adhesive retardation layer 2 usually has homeotropic alignment.

According to the present invention, at least one polymerizable functional group selected from the group consisting of the above formulas (I), (II), (III), (IV), and (V) is provided on the adhesive retardation layer. And a polymer of a polymerizable monomer having a carbon content ratio of 3 or more is included, thereby improving the adhesion between the adhesive retardation layer and the transparent substrate made of the cycloolefin resin. be able to. For this reason, according to the present invention, a retardation film using a transparent substrate made of a cycloolefin-based resin is obtained, and a retardation film having excellent adhesion between the adhesive retardation layer and the transparent substrate is obtained. Can do.
Here, the adhesion between the transparent substrate and the adhesive retardation layer can be improved by containing a polymer of the polymerizable monomer having the structure in the adhesive retardation layer as follows. Based on the reason.
In other words, cycloolefin resins have a problem of poor adhesion to liquid crystal materials generally used for retardation films and the like, but this is widely used for transparent substrates for retardation films. It is thought that the main cause was that the molecular polarity was lower than that of cellulose triacetate.
In this regard, in the retardation film of the present invention, the polymerizable monomer constituting the polymer of the polymerizable monomer contained in the adhesive retardation layer is represented by the above formulas (I), (II), (III), ( IV) and having at least one polymerizable functional group selected from the group consisting of (V) and having a carbon content ratio of 3 or more, the polarity of the polymerizable monomer is changed. It can be approximated to the polarity of the cycloolefin resin. For this reason, since the polymer of the polymerizable monomer used in the present invention has excellent adhesion to the cycloolefin-based resin, the adhesion between the adhesion retardation layer and the transparent substrate is improved. It is considered possible.

Further, there is a relationship of nx = ny <nz between the refractive indexes nx and ny in any x direction and y direction in which the adhesive retardation layer is orthogonal to each other in the in-plane direction and the refractive index nz in the thickness direction. By being established, the retardation film of the present invention can be imparted with a property as a positive C plate.
In the present invention, since the liquid crystal material contained in the adhesive retardation layer has a homeotropic alignment capable of forming a homeotropic alignment without using a vertical alignment film, The liquid crystal material contained in the phase difference layer usually has a homeotropic alignment. For this reason, in the present invention, due to the contribution of the birefringence of the liquid crystal material having such homeotropic alignment, the above-mentioned adhesion phase difference layer is naturally established in the above-mentioned relationship between nx, ny and nz. It can be done.
Therefore, according to the present invention, a retardation film having properties as a positive C plate using a transparent substrate made of a cycloolefin resin, comprising an adhesive retardation layer and a transparent substrate, A retardation film having excellent adhesion can be obtained.

  In addition, the retardation film of the present invention has an adhesion function in which the adhesive retardation layer improves adhesion to the transparent substrate, and a retardation imparting function that imparts retardation to the retardation film of the present invention. Therefore, for example, it has an advantage that the manufacturing process can be simplified as compared with a retardation film separately having the layer having the adhesion function and the layer having the retardation imparting function.

The retardation film of the present invention has at least a transparent substrate and an adhesive retardation layer.
Hereafter, each structure used for the retardation film of this invention is demonstrated in order.

1. Adhesive Retardation Layer First, the adhesive retardation layer used in the present invention will be described. The adhesive retardation layer used in the present invention has at least one polymerizable functional group selected from the group consisting of the above formulas (I), (II), (III), (IV), and (V). And a polymer of a polymerizable monomer having a carbon content ratio of 3 or more and a liquid crystal material having homeotropic orientation, and any x direction and y direction perpendicular to each other in the in-plane direction The relationship of nx = ny <nz is established between the refractive indexes nx and ny of ## EQU1 ## and the refractive index nz in the thickness direction.
And the adhesive phase difference layer used for this invention has a function which provides the property as a positive C plate to the phase difference film of this invention.

  As described above, in the present invention, the adhesive phase difference layer contains a polymer of the polymerizable monomer having the above structure, so that the adhesion between the adhesive phase difference layer and the transparent substrate is excellent. A phase difference film can be obtained.

  Hereinafter, such an adhesive retardation layer will be described in detail.

(1) Polymerized product of polymerizable monomer First, the polymerized product of the polymerizable monomer used in the present invention will be described. The polymer of the polymerizable monomer used in the present invention is at least one polymerizable functional group selected from the group consisting of the above formulas (I), (II), (III), (IV), and (V). And a polymerizable monomer having a carbon content ratio of 3 or more is polymerized.

(Polymerizable monomer)
The polymerizable monomer used in the present invention has at least one polymerizable functional group selected from the group consisting of the above formulas (I), (II), (III), (IV) and (V). And the carbon content ratio is 3 or more. Since the polymerizable monomer used in the present invention has a carbon content ratio within the above range, the polarity of the polymerizable monomer can be approximated to the polarity of the cycloolefin resin constituting the transparent substrate described later. It is possible to improve the adhesion between the crystalline retardation layer and the transparent substrate described later.

  The carbon content ratio of the polymerizable monomer used in the present invention is not particularly limited as long as it is within the range specified in the present invention, and is arbitrary according to the type of cycloolefin resin constituting the transparent substrate described later. Can be determined. Among them, the polymerizable monomer used in the present invention preferably has a carbon content in the range of 3 to 10, particularly preferably in the range of 3 to 7, and more preferably in the range of 3 to 5. Some are preferred. The carbon content ratio indicates that the larger the value, the smaller the polarity of the polymerizable monomer. Therefore, when the carbon content ratio is smaller than the above range, the polarity of the polymerizable monomer becomes too large, and the transparency described later This is because the difference between the polarity of the cycloolefin-based resin constituting the substrate widens, and as a result, the adhesion between the transparent substrate and the adhesive retardation layer described later may be insufficient. On the other hand, if it is larger than the above range, the ratio of the polymerizable functional group contained in the polymerizable monomer becomes too small, and the solvent resistance of the adhesive retardation layer may be impaired.

Here, as described above, the carbon content ratio is a value (N / M) obtained by dividing the carbon number N constituting the polymerizable monomer by the number M of elements other than carbon and hydrogen constituting the polymerizable monomer. However, “the number N of carbon atoms constituting the polymerizable monomer” means the number of carbons indicated when the polymerizable monomer is represented by a molecular formula. The “number of elements M other than carbon and hydrogen constituting the polymerizable monomer” means the sum of the numbers of elements other than carbon and hydrogen expressed when the polymerizable monomer is expressed by a molecular formula. Is. Therefore, for example, in the case of 1,6-hexanediol diacrylate having a molecular formula of C ₁₂ H ₁₈ O ₄ , the number of carbon atoms N constituting the polymerizable monomer is 12, other than carbon and hydrogen constituting the polymerizable monomer. Since the number of elements M is 4, the above N / M is 3. In the case of acryloylmorpholine having a molecular formula of C ₇ H ₁₁ NO ₂ , the number N of carbon atoms constituting the polymerizable monomer is 7, and the number M of elements other than carbon and hydrogen constituting the polymerizable monomer is 3 (nitrogen). + / Oxygen), the N / M is 2.3.

  The polymerizable monomer used in the present invention may contain one of the polymerizable functional groups in the molecule or may contain a plurality of polymerizable functional groups. In particular, in the present invention, it is preferable to use a polymerizable monomer containing a plurality of polymerizable functional groups. Thereby, since the crosslinking density of the polymerized polymerizable monomer in the adhesive retardation layer can be increased, an adhesive retardation layer having excellent solvent resistance can be obtained.

  In addition, when the polymerizable monomer used in the present invention is formed by bonding a plurality of the polymerizable functional groups, all of the polymerizable functional groups may be the same or different from each other.

  Moreover, it is preferable that the polymerizable monomer used for this invention has an aliphatic hydrocarbon. By having such an aliphatic hydrocarbon, the carbon content ratio is within the range specified in the present invention, and the polarity of the polymerizable monomer used in the present invention is close to the polarity of the cycloolefin resin. This is because it becomes easy.

  The aliphatic hydrocarbon used in the present invention may be a linear one, a branched one, or a cyclic one. It is preferably linear or cyclic. Since the hydrocarbon chain is linear or cyclic, the molecular structure of the polymerizable monomer can be approximated by the molecular structure of a cycloolefin-based resin, which will be described later. As a result, it is possible to obtain a retardation film having more excellent adhesion between the transparent substrate and the adhesion retardation layer.

The polymerizable monomer used in the present invention preferably has a hydroxyl value of 150 mgKOH / g or less, more preferably 50 mgKOH / g or less, and particularly preferably 5 mgKOH / g or less. Further, the polymerizable monomer used in the present invention preferably has an acid value of 150 mgKOH / g or less, more preferably 50 mgKOH / g or less, and particularly preferably 5 mgKOH / g or less.
When the polymerizable monomer used in the present invention has a highly polar hydroxyl group and acidic group (such as carboxylic acid, phosphoric acid, and sulfonic acid), and either the hydroxyl value or acid value is higher than 150 mgKOH / g, the carbon content ratio Even within the range specified in the present invention, it becomes difficult to approximate the polarity of the polymerizable monomer to the polarity of the cycloolefin resin described later, and the adhesion between the adhesive retardation layer and the transparent substrate is lowered. It is because it is assumed that it is.
Here, the hydroxyl value can be measured by a method based on JIS K0070. Moreover, the said acid value can be measured by the method based on JISK2501.

  Specific examples of the polymerizable monomer used in the present invention include, for example, polymerizable monomers represented by the following formulas (VI) and (VII).

In the above formula, X ¹ , X ² , and X ³ are each independently a polymerizable functional group of any one of the above formulas (I), (II), (III), (IV), and (V). To express. Y ¹ is a linear or branched hydrocarbon represented by —C _m H _{2m + 1} (m is an integer of 4 to 17), a cyclohexyl group, an isobornyl group, an unsubstituted group or an alkyl group. Represents a phenyl group or a biphenyl group. r ¹ , r ² , r ³ and r ⁴ are each independently 0 or 1;
Further, Y ² represents a linear or branched hydrocarbon represented by —C _n H _2n — (n is an integer of 1 to 34), a cyclohexyl group, a tricyclodecanedimethyl group, a phenyl group, Or represents a biphenyl group.

  In the present invention, among the polymerizable monomers represented by the above formulas (VI) and (VII), the following polymerizable monomers are preferably used (hereinafter, numerical values in <> Indicates the carbon content ratio of the compound.)

A polymerizable monomer having a polymerizable functional group represented by the above formula (I); cyclohexyl acrylate <4.5>, isobornyl acrylate <6.5>, 1,6-hexanediol diacrylate <3>, 1 , 9-nonanediol diacrylate <3.75>, 2-methyl-1,8-octanediol diacrylate <3.75>, 2-butyl-2-ethyl-1,4-propanediol diacrylate <3. 75>, 1,10-decanediol diacrylate <3.75>, tricyclodecane dimethanol diacrylate <4.5>.
Polymerizable monomer having a polymerizable functional group represented by the above formula (II): 1,6-hexanediol divinyl ether <5>, cyclohexanediol divinyl ether <5>, cyclohexanedimethanol divinyl ether <6>, nonanediol Divinyl ether <6.5>, trimethylpropane trivinyl ether <4>.
A polymerizable monomer having a polymerizable functional group represented by the above formula (III); ethylhexyl glycidyl ether <5.5>.
A polymerizable monomer having a polymerizable functional group represented by the above formulas (III) and (IV); dipentene dioxide <5>.
A polymerizable monomer having a polymerizable functional group represented by the above formula (V); 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane <7>, di [1-ethyl (3-oxetanyl)] methyl Ether <4>.
A polymerizable monomer having a polymerizable functional group represented by the above formulas (I) and (V); 3-ethyl-3-oxetanylmethyl acrylate <3>.

  In addition, it can be clarified, for example, by NMR analysis that the polymerizable phase difference layer in the present invention contains a polymer of the polymerizable monomer.

(Polymerized monomer)
Next, the polymerized polymerizable monomer used in the present invention will be described. The polymerized polymerizable monomer used in the present invention is obtained by polymerizing the polymerizable monomer described above.

  The polymer of the polymerizable monomer used in the present invention is not particularly limited as long as it is obtained by polymerizing the polymerizable monomer described above. Examples of such a polymerized product of polymerizable monomers include an embodiment in which only the same polymerizable monomer is polymerized and an embodiment in which two or more kinds of polymerizable monomers are polymerized. In the present invention, any of the polymerizable monomers can be suitably used. However, among these, the polymerizable monomer polymerized only in the same polymerizable monomer is used. Is preferred.

Moreover, as content of the polymer of the polymerizable monomer contained in the adhesive phase difference layer in the present invention, a range in which the adhesiveness between the adhesive phase difference layer and the transparent substrate described later can be within a desired range. If it is, it will not specifically limit. Especially in this invention, it is preferable to exist in the range of 0.01 mass%-30 mass% with respect to the liquid crystal material which forms homeotropic alignment, and it is especially the range of 1 mass%-20 mass%. preferable.
When the content is more than the above range, it may be difficult to impart desired retardation to the retardation film of the present invention. On the other hand, when the content is less than the above range, the adhesive retardation layer and the transparent film are transparent. This is because the adhesive strength with the substrate may not be within a desired range.

(2) Liquid Crystal Material Next, the liquid crystal material used in the present invention will be described. The liquid crystal material used in the present invention has homeotropic alignment.

Here, in the present invention, since the liquid crystal material has homeotropic alignment, the liquid crystal material in the adhesive retardation layer usually forms homeotropic alignment. And, by such homeotropic alignment of the liquid crystal material, the adhesive retardation layer in the present invention satisfies the relationship of nx = ny <nz.
Therefore, the fact that the adhesive retardation layer used in the present invention has the relationship of nx = ny <nz is in agreement with the liquid crystal material forming homeotropic alignment in the adhesive retardation layer. I can say that.

  The “homeotropic orientation” in the present invention means a property capable of forming homeotropic orientation without using a vertical alignment film.

  The liquid crystal material used in the present invention is not particularly limited as long as it has homeotropic alignment, but preferably has a polymerizable functional group. This is because by using such a liquid crystal material, they can be polymerized with each other via a polymerizable functional group, so that the mechanical strength of the adhesive retardation layer in the present invention can be improved. In addition, the alignment stability of the liquid crystal material in the adhesive retardation layer can be improved.

  As the polymerizable functional group, various polymerizable functional groups that are polymerized by the action of ionizing radiation such as ultraviolet rays and electron beams, or heat are used. Representative examples of these polymerizable functional groups include radically polymerizable functional groups or cationic polymerizable functional groups. Further, representative examples of radically polymerizable functional groups include functional groups having at least one addition-polymerizable ethylenically unsaturated double bond, and specific examples include vinyl groups having or not having substituents, An acrylate group (generic name including an acryloyl group, a methacryloyl group, an acryloyloxy group, and a methacryloyloxy group) and the like can be given. Specific examples of the cationic polymerizable functional group include an epoxy group. In addition, examples of the polymerizable functional group include an isocyanate group and an unsaturated triple bond. In the present invention, among these polymerizable functional groups, a functional group having an ethylenically unsaturated double bond is preferably used from the viewpoint of the process.

  In addition, the liquid crystal material used in the present invention may have a plurality of the above-described polymerizable functional groups, or may have only one.

  Specific examples of such a liquid crystal material include, for example, a monomer unit containing a liquid crystal fragment side chain having positive refractive index anisotropy and a monomer unit containing a non-liquid crystal fragment side chain. Examples of the liquid crystal polymer include a chain type liquid crystal polymer and a side chain type liquid crystal polymer containing a monomer unit containing the liquid crystalline fragment side chain and a monomer unit containing a liquid crystalline fragment side chain having an alicyclic ring structure. be able to. Examples of such a liquid crystal polymer include compounds described in JP-A No. 2003-121853, JP-A No. 2002-174725, and JP-A No. 2005-70098.

The liquid crystal material used in the present invention may be one kind or two or more kinds. When two or more kinds of liquid crystal materials are used, a liquid crystal material having homeotropic orientation and a liquid crystal material having no homeotropic orientation may be mixed and used.
Here, the above “liquid crystal material having no homeotropic alignment” means a liquid crystal material that cannot form homeotropic alignment by itself, but can form homeotropic alignment by using a vertical alignment film. To do.

  The liquid crystal material having no homeotropic alignment used in the present invention is not particularly limited, but preferably has a polymerizable functional group as described above. By using such a liquid crystal material, it is possible to polymerize with a liquid crystal material having homeotropic orientation via a polymerizable functional group, so that the mechanical strength of the adhesive retardation layer in the present invention can be improved. Because. In addition, the alignment stability of the liquid crystal material in the adhesive retardation layer can be improved.

Note that the liquid crystal material having no homeotropic alignment used in the present invention may have a plurality of the above-described polymerizable functional groups, or may have only one, However, in the present invention, those having a plurality of polymerizable functional groups are preferably used. The reason is as follows.
That is, since many liquid crystal materials having homeotropic alignment generally have a structure having only one polymerizable functional group in the molecule, only such a liquid crystal material has excellent mechanical strength. It may be difficult to form an adhesive retardation layer. However, a liquid crystal material having homeotropic alignment and a liquid crystal material having no homeotropic alignment can be obtained by mixing with a liquid crystal material having a plurality of polymerizable functional groups and not homeotropic alignment. This is because the adhesion retardation layer having excellent mechanical strength can be easily formed.

  Specific examples of such a liquid crystal material having no homeotropic alignment are described in, for example, JP-A-7-258638, JP-A-10-508882, and JP-A-2003-287623. Such compounds can be mentioned. In particular, in the present invention, a compound represented by the following chemical formula can be preferably used.

  Further, specific examples of the liquid crystal material having no homeotropic alignment include compounds described in JP-A-10-319408. In particular, in the present invention, a compound represented by the following chemical formula can be preferably used.

In the above formula, x is 1 to 12, Z is a 1,4-phenylene group or 1,4-cyclohexylene group, R ⁵ is halogen or cyano, or has 1 to 12 carbon atoms. An alkyl group or an alkoxy group, and L is H, halogen or CN, or an alkyl group, an alkoxy group or an acyl group having 1 to 7 carbon atoms.

  Moreover, it is preferable that the liquid crystal material used in the present invention has the same polymerizable functional group as the polymerizable functional group of the polymerizable monomer described above. By using such a liquid crystal material, the polymerizable monomer and the liquid crystal material can be polymerized at the same time in the step of producing the retardation film of the present invention, so that the retardation film of the present invention is more productive. It is because it can be made high.

  When a compound having a polymerizable functional group is used as the liquid crystal material, the liquid crystal material contained in the adhesive retardation layer in the present invention is a polymer polymerized through the polymerizable functional group.

(3) Other compounds The adhesive retardation layer in the invention may contain a compound other than the polymer of the polymerizable monomer and the liquid crystal material. As said other compound used for this invention, according to the use etc. of the phase difference film of this invention, if a desired functionality can be provided to the said adhesive phase difference layer, it will not specifically limit. . Among them, examples of the other compound that can be suitably used in the present invention include an alignment control compound that assists in forming homeotropic alignment of the liquid crystal material in the adhesive retardation layer.

  As an alignment control compound used in the present invention, by being contained in the adhesive alignment layer, it can assist in forming homeotropic alignment of the liquid crystal material and can impart desired retardation to the retardation film of the present invention. If it is a thing, it will not specifically limit. Among these, as the alignment control compound used in the present invention, a surfactant can be preferably used. This is because the surfactant is suitable for assisting in forming homeotropic alignment of the liquid crystal material because it can be arranged by being present at the air interface in the adhesive retardation layer.

  Examples of the surfactant include a sulfonate surfactant, and a fluorinated sulfonate surfactant is particularly preferably used.

  Specific examples of the fluorinated sulfonate surfactant include trade names FC-4430 and FC-4432 (both manufactured by 3M Company).

  The content of the orientation control compound in the adhesive retardation layer is particularly limited as long as it can impart a desired retardation to the retardation film of the present invention, depending on the type of the orientation control compound. Not. In particular, the content of the alignment control compound in the present invention is preferably within a range of 0.01% by mass to 10% by mass with respect to the liquid crystal material, and particularly within a range of 0.01% by mass to 3% by mass. Preferably there is.

  In addition to the above, examples of the other compound used in the present invention include a polymerization initiator, a polymerization inhibitor, a plasticizer, a surfactant, and a silane coupling agent. In particular, when the polymerizable liquid crystal material is used as the liquid crystal material, it is preferable to use a polymerization initiator or a polymerization inhibitor as the other compound.

  Examples of the polymerization initiator include benzophenone, methyl o-benzoylbenzoate, 4,4-bis (dimethylamine) benzophenone, 4,4-bis (diethylamine) benzophenone, α-amino acetophenone, 4,4-dichloro. Benzophenone, 4-benzoyl-4-methyldiphenyl ketone, dibenzyl ketone, fluorenone, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2-hydroxy-2-methylpropiophenone, p- tert-Butyldichloroacetophenone, thioxanthone, 2-methylthioxanthone, 2-chlorothioxanthone, 2-isopropylthioxanthone, diethylthioxanthone, benzyldimethyl ketal, benzylmethoxyethyl acetal, benzo Methyl ether, benzoin butyl ether, anthraquinone, 2-tert-butylanthraquinone, 2-amylanthraquinone, β-chloroanthraquinone, anthrone, benzanthrone, dibenzsuberone, methyleneanthrone, 4-azidobenzylacetophenone, 2,6-bis (p- Azidobenzylidene) cyclohexane, 2,6-bis (p-azidobenzylidene) -4-methylcyclohexanone, 2-phenyl-1,2-butadion-2- (o-methoxycarbonyl) oxime, 1-phenyl-propanedione-2 -(O-ethoxycarbonyl) oxime, 1,3-diphenyl-propanetrione-2- (o-ethoxycarbonyl) oxime, 1-phenyl-3-ethoxy-propanetrione-2- (o-benzoyl) oxy , Michler's ketone, 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone, naphthalene Sulfonyl chloride, quinoline sulfonyl chloride, n-phenylthioacridone, 4,4-azobisisobutyronitrile, diphenyl disulfide, benzthiazole disulfide, triphenylphosphine, camphorquinone, Adeka N1717, carbon tetrabromide, tri Examples include combinations of photoreducing dyes such as bromophenyl sulfone, benzoin peroxide, eosin, and methylene blue with reducing agents such as ascorbic acid and triethanolamine. In this invention, these photoinitiators can be used 1 type or in combination of 2 or more types.

  Furthermore, when using the said photoinitiator, a photoinitiator adjuvant can be used together. Examples of such photopolymerization initiation assistants include tertiary amines such as triethanolamine and methyldiethanolamine, and benzoic acid derivatives such as ethyl 2-dimethylaminoethylbenzoate and ethyl 4-dimethylamidebenzoate. Yes, but not limited to these.

  Examples of the polymerization inhibitor include diphenylpicrylhydrazide, tri-p-nitrophenylmethyl, p-benzoquinone, p-tert-butylcatechol, picric acid, copper chloride, methylhydroquinone, methoquinone, tert-butylhydroquinone and the like. Although a polymerization inhibitor for the reaction can be used, a hydroquinone polymerization inhibitor is preferred from the viewpoint of storage stability, and methyl hydroquinone is particularly preferred.

  Furthermore, the following compounds can be added to the adhesive retardation layer in the present invention within the range not impairing the object of the present invention. Examples of compounds that can be added include polyester (meth) acrylate obtained by reacting (meth) acrylic acid with a polyester prepolymer obtained by condensing polyhydric alcohol and monobasic acid or polybasic acid; A polyurethane (meth) acrylate obtained by reacting a compound having two isocyanate groups with each other and then reacting the reaction product with (meth) acrylic acid; bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolak Type epoxy resins, polycarboxylic acid polyglycidyl esters, polyol polyglycidyl ethers, aliphatic or cycloaliphatic epoxy resins, amino group epoxy resins, triphenolmethane type epoxy resins, dihydroxybenzene type epoxy resins and the like (meta Acu Photopolymerizable compounds such as epoxy (meth) acrylate obtained by reacting Le acid; photopolymerizable liquid crystal compound having an acryl group or methacryl group and the like.

(4) Adhesive Retardation Layer The thickness of the adhesive retardation layer used in the present invention is within a range in which a desired retardation can be expressed depending on the type of the polymerizable monomer or the liquid crystal material. It is not particularly limited. Especially in this invention, it is preferable to exist in the range of 0.1 micrometer-10 micrometers, and it is especially preferable to exist in the range of 0.1 micrometer-5 micrometers.

The adhesive retardation layer in the present invention exhibits retardation, but such retardation can be arbitrarily adjusted according to the use of the retardation film of the present invention. In particular, the retardation layer (Rth) in the thickness direction of the adhesive retardation layer in the present invention is preferably in the range of −1000 nm to 0 nm, and more preferably in the range of −300 nm to 0 nm.
Here, the above-mentioned retardation in the thickness direction (hereinafter sometimes simply referred to as “Rth”) refers to refractive indices in arbitrary x and y directions orthogonal to each other in the in-plane direction, respectively nx, ny, It is an amount represented by Rth = {(nx + ny) / 2−nz} × d, where nz is the refractive index in the thickness direction and d is the thickness. Moreover, the said thickness direction retardation can be measured by a parallel Nicol rotation method, for example using KOBRA-WR by Oji Scientific Instruments.

2. Transparent substrate Next, the transparent substrate used in the present invention will be described. The transparent substrate used in the present invention is made of a cycloolefin resin.

  Here, the cycloolefin resin in the present invention means a resin having a monomer unit composed of a cyclic olefin (cycloolefin). Moreover, as a monomer which consists of the said cyclic olefin, a norbornene, a polycyclic norbornene-type monomer, etc. can be mentioned, for example.

  The cycloolefin resin used in the present invention may be a homopolymer of a monomer comprising the above cyclic olefin, or may be a copolymer.

The cycloolefin-based resin used in the present invention is not particularly limited as long as a transparent substrate having desired transparency can be obtained. Among them, the cycloolefin resin used in the present invention preferably has a saturated water absorption at 23 ° C. of 1% by mass or less, and particularly preferably within a range of 0.1% by mass to 0.7% by mass. . This is because by using such a cycloolefin-based resin, it is possible to make the retardation film of the present invention less susceptible to changes in optical properties and dimensions due to water absorption.
Here, the saturated water absorption is obtained by immersing in 23 ° C. water for 1 week according to ASTM D570 and measuring the increased weight.

  In addition, the cycloolefin resin used in the present invention preferably has a glass transition point in the range of 100 ° C to 200 ° C, particularly preferably in the range of 100 ° C to 180 ° C, and in particular, 100 ° C. What is in the range of -150 degreeC is preferable. This is because, when the glass transition point is within the above range, the retardation film of the present invention can be made more excellent in heat resistance and processability.

  Examples of such a cycloolefin resin include those having a structural unit represented by the following formula (a) or the following formula (b).

Here, in the above formula (a), t and u each independently represent 0 or a positive integer, except when t and u are 0 at the same time. A represents an ethylene group or a vinylene group, and R ^{11 to} R ¹⁴ are each independently a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 30 carbon atoms, or — (CH ₂ ) n—COOR ( n represents 0 to 5, and R represents an alkyl group having 1 to 12 carbon atoms.
Here, R ¹¹ or R ¹² and R ¹³ or R ¹⁴ may be bonded to each other to form a carbocyclic or heterocyclic ring. Furthermore, the carbocycle or heterocycle may be a monocyclic structure or a polycyclic structure.

In the above formula (b), B represents an ethylene group or a vinylene group. R ^{15 to} R ¹⁸ each independently represent a hydrogen atom, a halogen atom, or a hydrocarbon group having 1 to 30 carbon atoms. Further, R ¹⁵ and R ¹⁶ , or R ¹⁷ and R ¹⁸ may be integrated to form a divalent hydrocarbon group.

  In the transparent substrate used in the present invention, only one kind of the cycloolefin-based resin may be used, or two or more kinds may be used.

The transparency of the transparent substrate used in the present invention may be arbitrarily determined according to the use of the retardation film of the present invention, etc., but it is usually preferable that the transmittance in the visible light region is 80% or more, 90 % Or more is more preferable. When the transmittance is in the above range, for example, when the retardation film of the present invention is used for a viewing angle compensation film of a liquid crystal display device, it is possible to prevent the display luminance of the liquid crystal display device from being lowered. Because.
Here, the transmittance of the transparent substrate can be measured by JIS K7361-1 (a test method for the total light transmittance of a plastic-transparent material).

  The thickness of the transparent substrate used for this invention will not be specifically limited if it is in the range which can provide desired self-supporting property. Especially in this invention, it is preferable to exist in the range of 25 micrometers-1000 micrometers, and it is especially preferable to exist in the range of 30 micrometers-100 micrometers. This is because if the thickness of the transparent substrate is thinner than the above range, the necessary self-supporting property may not be imparted to the transparent substrate of the present invention. Moreover, when the thickness is thicker than the above range, for example, when cutting the retardation film of the present invention, the processing waste may increase or the cutting blade may be worn quickly.

  The configuration of the transparent substrate in the present invention is not limited to a configuration composed of a single layer, and may have a configuration in which a plurality of layers are laminated. When it has the structure by which the several layer was laminated | stacked, the layer of the same composition may be laminated | stacked, and the several layer which has a different composition may be laminated | stacked.

The transparent substrate used in the present invention may exhibit retardation. Such retardation is not particularly limited as long as a desired refractive index anisotropy can be imparted to the retardation film according to the use of the retardation film of the present invention. In particular, the transparent substrate used in the present invention preferably has an in-plane retardation in the range of 0 nm to 1000 nm, and particularly preferably in the range of 0 nm to 300 nm.
Here, the in-plane retardation (hereinafter sometimes simply referred to as “Re”) is the refractive index in the slow axis direction in the plane of the transparent substrate is nx, and the in-plane fast axis direction is in the in-plane retardation direction. When the refractive index is ny and the thickness of the transparent substrate is d, Re = (nx−ny) × d. The Re can be measured by, for example, a parallel Nicol rotation method using KOBRA-WR manufactured by Oji Scientific Instruments.

  Specific examples of the transparent substrate made of cycloolefin resin used in the present invention include, for example, Ticona Topas, JSR Arton, ZEON Corporation ZEONOR, ZEON Corporation ZEONEX, Mitsui Chemicals, Inc. Can be mentioned.

3. Retardation film The retardation exhibited by the retardation film of the present invention can be appropriately determined according to the use of the retardation film of the present invention. Among them, the retardation film of the present invention has an Nz factor of 1. Is preferably 0.0 or less, and more preferably in the range of −1.5 ≦ Nz <1.0.
Here, the Nz factor is a parameter that defines the shape of the refractive index ellipsoid. It is determined by the refractive indices nx and ny in the arbitrary x direction and y direction orthogonal to each other in the in-plane direction, and the refractive index nz in the thickness direction. Is represented by the following equation.
Nz = (nx-nz) / (nx-ny)
The Nz factor can be obtained by, for example, measuring nx, ny, and nz by the parallel Nicol rotation method using KOBRA-WR manufactured by Oji Scientific Instruments Co., Ltd., and then calculating according to the above formula. it can.

  The Re wavelength dispersion of the retardation film of the present invention may be a reverse dispersion type in which the Re value decreases as the wavelength becomes shorter, or a positive dispersion type in which the Re value increases as the wavelength becomes shorter. Alternatively, a flat type in which the Re value does not have wavelength dependency may be used.

  The form of the retardation film of the present invention is not particularly limited, and may be, for example, a sheet shape that matches the screen size of a liquid crystal display device using the retardation film of the present invention, or a long shape. There may be.

4). Use of Retardation Film The retardation film of the present invention can be used as a viewing angle compensation film, an elliptically polarizing plate, a brightness enhancement film and the like used in a liquid crystal display device.

  When the retardation film of the present invention is used as a viewing angle compensation film for a liquid crystal display device, the retardation film of the present invention can be used alone, and the retardation film of the present invention and other optical functions can be used. It is also possible to use it laminated with a film. Furthermore, it is also possible to directly laminate another adhesive retardation layer on the surface opposite to the side on which the adhesive retardation layer is formed of the transparent substrate used in the retardation film of the present invention. .

  As an example of laminating and using the retardation film of the present invention and another optical functional film, for example, by laminating a liquid crystal layer containing cholesteric aligned liquid crystal molecules on the retardation film of the present invention, Examples of use as a brightness enhancement film for liquid crystal display devices can be given.

  Moreover, the retardation film of this invention can be used also for the use as a polarizing plate by bonding together with a polarizer. That is, the polarizing plate is usually composed of a polarizer and a polarizing plate protective film formed on both surfaces thereof. In the present invention, for example, as one polarizing plate protective film, the retardation of the present invention is used. By using a film, it can be used as a polarizing plate having a viewing angle compensation function of a liquid crystal display device.

5. Production method of retardation film The production method of the retardation film of the present invention is not particularly limited as long as it can produce the retardation film having the above-described configuration. As such a method, the manufacturing method demonstrated in the term of the "B. manufacturing method of retardation film" mentioned later, for example can be used.

B. Next, a method for producing the retardation film of the present invention will be described. The method for producing a retardation film of the present invention uses a transparent substrate made of a cycloolefin-based resin, and at least a polymerizable monomer and a liquid crystal material having homeotropic orientation are dissolved in a solvent, and a coating for forming an adhesive retardation layer. In the adhesive phase difference layer forming layer forming step, the adhesive phase difference layer forming layer is formed by coating the working liquid so as to be in contact with the transparent substrate, and in the adhesive phase difference layer forming layer. A curing treatment step of forming an adhesive retardation layer by polymerizing a polymerizable monomer contained in the substrate, and refraction in any x direction and y direction perpendicular to each other in the in-plane direction on the transparent substrate. A retardation film in which an adhesive retardation layer in which a relationship of nx = ny <nz is established between the ratios nx and ny and the refractive index nz in the thickness direction is produced. Mo The mer has at least one polymerizable functional group selected from the group consisting of the following formulas (I), (II), (III), (IV), and (V), and the polymerization The value (N / M) obtained by dividing the carbon number N constituting the polymerizable monomer by the number M of elements other than carbon and hydrogen constituting the polymerizable monomer is 3 or more.

Here, in the above formula, R ¹ , R ² and R ³ represent a methyl group or hydrogen. R ⁴ represents hydrogen, a methyl group, or an ethyl group.

Such a method for producing a retardation film of the present invention will be described with reference to the drawings. FIG. 2 is a schematic view showing an example of a method for producing a retardation film of the present invention. As illustrated in FIG. 2, the method for producing a retardation film of the present invention uses a transparent substrate 1 made of a cycloolefin-based resin (FIG. 2 (a)), and at least a polymerizable monomer and a liquid crystal material having homeotropic orientation. Adhesive Retardation Layer Forming Layer 2 'is Adhesive Retardation Layer Forming Layer 2' by Applying an Adhesive Retardation Layer Forming Coating Solution Dissolved in a Solvent to Contact the Transparent Substrate 1 A layer forming step for forming a layer (FIG. 2B), and a curing treatment step (FIG. 2C) for polymerizing the polymerizable monomer contained in the adhesive phase difference layer forming layer 2 ′. Through such a process, on the transparent substrate 1, between any refractive index nx and ny in the x direction and y direction orthogonal to each other in the in-plane direction and the refractive index nz in the thickness direction, dense where the relationship of nx = ny <nz holds It is intended to produce a retardation film 10 that sexual retardation layer 2 was formed (Figure 2 (d)).
In such an example, in the method for producing a retardation film of the present invention, the polymerizable monomer contained in the adhesive phase difference layer forming coating liquid is represented by the above formulas (I), (II), (III). , (IV), and (V) having at least one polymerizable functional group selected from the group consisting of carbon atoms constituting the polymerizable monomer and N constituting the polymerizable monomer. And the value (N / M) divided by the number M of elements other than hydrogen is 3 or more.

According to the present invention, at least one selected from the group consisting of the above formulas (I), (II), (III), (IV), and (V) is used as the adhesive retardation layer forming coating solution. In the retardation film produced according to the present invention, the adhesive phase-difference layer is produced by including a polymer of a polymerizable monomer having one polymerizable functional group and a carbon content ratio of 3 or more, Adhesion with a transparent substrate made of a cycloolefin resin can be improved. For this reason, according to the present invention, a retardation film using a transparent substrate made of a cycloolefin-based resin is manufactured, and the retardation film having excellent adhesion between the adhesive retardation layer and the transparent substrate is produced. be able to.
Further, the retardation film produced according to the present invention has a refractive index nx and ny in any x direction and y direction orthogonal to each other in the in-plane direction, and a refractive index nz in the thickness direction, nx = ny < By having an adhesive retardation layer that satisfies the nz relationship, a retardation film having properties as a positive C plate can be produced according to the present invention.
Therefore, according to the present invention, a retardation film having properties as a positive C plate using a transparent substrate made of a cycloolefin resin, comprising an adhesive retardation layer and a transparent substrate, A retardation film having excellent adhesion can be produced.

  Here, the reason why a retardation film excellent in adhesion between the adhesive retardation layer and the transparent substrate can be produced by using the polymerizable monomer having the structure in the present invention is described above. Since it is the same as the reason demonstrated in the section of "A. Retardation film", description here is abbreviate | omitted.

The method for producing a retardation film of the present invention includes at least the above-mentioned adhesive retardation layer forming layer forming step and the above curing treatment step, and may include other steps as necessary. It is.
Hereinafter, each process used for the manufacturing method of the retardation film of this invention is demonstrated in order.

1. Adhesive retardation layer forming layer forming step First, the adhesive retardation layer forming layer forming step used in the present invention will be described. In this step, a transparent substrate made of a cycloolefin resin is used, and a coating solution for forming an adhesive retardation layer formed by dissolving at least a polymerizable monomer and a liquid crystal material having homeotropic orientation in a solvent is formed on the transparent substrate. It is the process of forming the layer for adhesion phase contrast layer formation by applying so that it may touch.
In this step, the polymerizable monomer has at least one polymerizable functional group selected from the group consisting of the above formulas (I), (II), (III), (IV), and (V). And having a carbon content ratio of 3 or more.

  Here, in the present invention, a retardation film having excellent adhesion between the adhesive retardation layer and the transparent substrate can be produced by using the compound having the structure as the polymerizable monomer. .

  Hereinafter, the layer forming process for forming an adhesive retardation layer used in the present invention will be described in detail.

(1) Adhesive Retardation Layer Forming Coating Solution First, the adhesive retardation layer forming coating solution used in this step will be described. The coating solution for forming an adhesive retardation layer used in this step is obtained by dissolving at least a polymerizable monomer and a liquid crystal material having homeotropic alignment in a solvent.

(solvent)
The solvent used in this step is not particularly limited as long as it can dissolve the polymerizable monomer and the liquid crystal material at a desired concentration. As the solvent used in this step, a cycloolefin-soluble solvent that is soluble in the polymerizable monomer and the liquid crystal material, and that is also soluble in a cycloolefin-based resin constituting the transparent substrate described later. Examples thereof include a cycloolefin-insoluble solvent which exhibits solubility in the polymerizable monomer and the liquid crystal material but does not exhibit solubility in the cycloolefin-based resin constituting the transparent substrate described later.

  Examples of the cycloolefin-soluble solvent used in this step include cyclohexanone, cyclopentanone, methyl isobutyl ketone, xylene, toluene, dichloroethane, n-pentane, n-hexane, n-octane, ethyl ether, tetrahydrofuran, and the like. Can do.

  On the other hand, examples of the cycloolefin-insoluble solvent used in this step include methanol, ethanol, isopropyl alcohol, acetone, methyl ethyl ketone, PGMEA, methyl acetate, ethyl acetate, dilute sulfuric acid, acetic acid, formic acid and the like.

In this step, any of the cycloolefin-soluble solvent and the cycloolefin-insoluble solvent can be suitably used. Therefore, the solvent used in this step may be composed of a simple substance of the cycloolefin-soluble solvent, or may be composed of a simple substance of the cycloolefin-insoluble solvent. In particular, in this step, it is preferable to use a mixed solvent of the cycloolefin-soluble solvent and the cycloolefin-insoluble solvent. The reason is as follows.
That is, when the cycloolefin-soluble solvent is used as the solvent used in this step, the surface of the transparent substrate is formed when the adhesive retardation layer forming layer is formed on the transparent substrate in this step by the action of the solvent. However, a part will elute to the adhesive phase difference layer forming layer side. Thereby, the adhesive retardation layer forming layer formed in this step has a region in which the adhesive retardation layer forming layer and the transparent substrate are partially mixed in the vicinity of the interface with the transparent substrate. Therefore, the adhesion between the two can be improved.
However, when the above cycloolefin-soluble solvent is used alone, the cycloolefin resin is excessively eluted from the transparent substrate when forming the adhesive retardation layer in this step, and as a result, the transparency of the transparent substrate and The optical properties may be impaired.
In this regard, by using a mixed solvent in which the cycloolefin-soluble solvent is mixed with the cycloolefin-soluble solvent as a solvent, the solubility of the entire solvent in the cycloolefin-based resin can be improved, such as the transparency and optical characteristics of the transparent substrate. It becomes possible to adjust to the extent which can improve the adhesiveness of a transparent substrate and the layer for adhesive orientation layer formation, without impairing.
For this reason, it is preferable to use a mixed solvent of the cycloolefin-soluble solvent and the cycloolefin-insoluble solvent in this step.

  When a mixed solvent of the cycloolefin-soluble solvent and the cycloolefin-insoluble solvent is used as the solvent used in this step, the mixing ratio of the two solvents is the type of the cycloolefin-soluble solvent and the cycloolefin-insoluble solvent or the above Depending on the type of cycloolefin resin, etc., the solubility for the cycloolefin resin as a whole solvent does not impair the transparency and optical properties of the transparent substrate, and the layer for forming an adhesive alignment layer. If it is the range which can improve adhesiveness with, it will not specifically limit. Among them, the mixed solvent used in this step is preferably such that the mixed amount of the cycloolefin-soluble solvent with respect to 100 parts by weight of the cycloolefin-insoluble solvent is in the range of 0 to 100 parts by weight, particularly 0 to What is in the range of 50 weight part is preferable.

  Specific examples of such a mixed solvent include, for example, acetone: toluene = 2: 1, acetone: toluene = 3: 1, acetone: toluene = 4: 1, acetone: cyclohexanone = 2: 1, acetone: cyclohexanone = 3. : 1, acetone: cyclohexanone = 4: 1, methyl ethyl ketone: toluene = 2: 1, methyl ethyl ketone: toluene = 3: 1, methyl ethyl ketone: toluene = 4: 1, methyl ethyl ketone: cyclohexanone = 2: 1, methyl ethyl ketone: cyclohexanone = 3: 1 And a mixed solvent of methyl ethyl ketone: cyclohexanone = 4: 1.

(Polymerizable monomer)
Next, the said polymerizable monomer used for this process is demonstrated. The polymerizable monomer used in this step has at least one polymerizable functional group selected from the group consisting of the above formulas (I), (II), (III), (IV), and (V). And carbon content ratio is 3 or more.

  Here, since the polymerizable monomer used in this step is the same as that described in the section “A. Retardation film”, description thereof is omitted here.

  Only one type of polymerizable monomer may be used in this step, or two or more types may be used.

  Moreover, as content of the said polymerizable monomer in the coating liquid for the said adhesive phase difference layer formation used for this process, in the phase difference film manufactured by this invention, an adhesive phase difference layer, a transparent substrate, If it is in the range which can make adhesiveness of desired range, it will not specifically limit. Especially in this process, it is preferable that it exists in the range of 0.01 mass%-30 mass% with respect to the liquid crystal material contained in the said coating liquid for adhesive phase difference layer formation, Especially 1 mass%- It is preferable to be within the range of 20% by mass. This is because if the content of the polymerizable monomer is less than the above range, the adhesive property between the adhesive retardation layer and the transparent substrate may be impaired in the retardation film produced according to the present invention. On the other hand, when the amount is larger than the above range, the homeotropic alignment of the liquid crystal material is inhibited, and it may be difficult to impart desired retardation to the retardation film produced according to the present invention.

(Liquid crystal material)
Next, the liquid crystal material used in this step will be described. The liquid crystal material used in this step has homeotropic alignment.

  Here, since the liquid crystal material used in this step is the same as that described in the section “A. Retardation film”, description thereof is omitted here.

  Only one type of liquid crystal material may be used in this step, or two or more types may be used.

  Moreover, it is preferable that the liquid crystal material used in this step has the same polymerizable functional group as the polymerizable functional group that the polymerizable monomer described above has. By using such a liquid crystal material, the polymerizable monomer and the liquid crystal material can be polymerized at the same time in the curing treatment step described later, so that the production efficiency of the retardation film according to the present invention can be improved. Because.

  The content of the liquid crystal material in the coating liquid for forming an adhesive retardation layer used in this step is particularly limited as long as a desired retardation can be imparted to the retardation film produced according to the present invention. It is not something. Especially in this process, it is preferable to exist in the range of 5 mass%-60 mass%, and it is especially preferable to exist in the range of 10 mass%-40 mass%.

(Other)
The adhesive phase difference layer forming coating solution used in this step may contain other compounds in addition to the polymerizable monomer and the liquid crystal material. As such another compound, a compound capable of imparting a desired function to the retardation film can be arbitrarily selected and used depending on the use of the retardation film produced according to the present invention. As such other compounds, for example, the same compounds as those described as the other compounds that can be contained in the adhesive retardation layer in the section of “A. Retardation film” can be used. .

(2) Transparent substrate Next, the transparent substrate used for this process is demonstrated. The transparent substrate used in this step is made of a cycloolefin resin.
Here, since the transparent substrate used in this step is the same as that described in the section “A. Retardation film”, description thereof is omitted here.

(3) Method for forming adhesive phase difference layer forming layer Next, in this step, an adhesive phase difference layer forming coating solution is applied onto the transparent substrate to thereby provide an adhesive position on the transparent substrate. A method of forming the phase difference layer forming layer will be described.

  In this step, as the method for applying the adhesive phase difference layer forming coating liquid on the transparent substrate, any method can be used as long as it can form an adhesive phase difference layer forming layer capable of achieving desired flatness. It is not particularly limited. Examples of such coating methods include gravure coating, reverse coating, knife coating, dip coating, spray coating, air knife coating, roll coating, printing, curtain coating, die coating, and casting. Method, bar coating method, extrusion coating method, E-type coating method and the like.

Moreover, as a drying method of the coating film of the said adhesive phase difference layer forming coating liquid, generally used drying methods, such as a heat drying method, a reduced pressure drying method, and a gap drying method, can be used, for example.
Note that the drying method used in this step is not limited to a single method, and, for example, a plurality of drying methods are adopted in such a manner that the drying method is sequentially changed according to the amount of solvent remaining in the coating film. May be.

2. Curing treatment step Next, the curing treatment step used in the present invention will be described. This step is performed by polymerizing the polymerizable monomer contained in the adhesive phase difference layer forming layer formed on the transparent substrate in the adhesive phase difference layer forming layer forming step. In this step, the phase difference layer forming layer is used as an adhesive phase layer.

  In the curing treatment step, the method for polymerizing the polymerizable monomer is not particularly limited as long as it is a method capable of inducing a polymerization reaction of the polymerizable monomer contained in the adhesive phase difference layer forming layer. Absent. Such a method depends on the type of the polymerizable monomer, but in general, a method of irradiating the adhesive retardation layer forming layer with ultraviolet light, or the adhesive retardation layer forming method. A method of heating the layer or the like is used.

  As the ultraviolet rays, those having a wavelength in the range of 150 nm to 500 nm, more preferably in the range of 250 nm to 450 nm are usually used.

  As described above, this step is a step of polymerizing the polymerizable monomer contained in the adhesive phase difference layer forming layer, but the liquid crystal contained in the adhesive phase difference layer forming layer. In the case where the material has a polymerizable functional group, it is preferable to polymerize the polymerizable monomer and the liquid crystal material simultaneously in this step.

3. Other Steps In the method for producing a retardation film of the present invention, other steps other than the above-mentioned adhesive retardation layer forming layer forming step and the above curing treatment step may be used. Such other process is not particularly limited as long as it can provide a desired function to the retardation film produced according to the present invention. In particular, as another process suitably used in the present invention, the liquid crystal material contained in the adhesive retardation layer after the layer forming process for forming the adhesive alignment layer and before the curing process is homeotropically aligned. An alignment treatment step can be given.

  In the present invention, the reason why the above alignment treatment step is suitably used is as follows. In other words, since the liquid crystal material used in the present invention has homeotropic alignment, the liquid crystal material is usually homeotropically aligned without performing a special step of homeotropic alignment of the liquid crystal material. Often it is possible. However, depending on the type of the liquid crystal material and the conditions for forming the adhesive retardation layer in the adhesive retardation layer forming layer forming step, homeotropic alignment formation of the liquid crystal material may be insufficient. . This is because in such a case, the liquid crystal material can be sufficiently homeotropically aligned by using the alignment treatment step.

  The method for homeotropic alignment of the liquid crystal material in the alignment treatment step is not particularly limited, but a method of heating the liquid crystal layer to a temperature higher than the transition temperature to the homeotropic liquid crystal phase is usually used.

4). Next, the retardation film produced according to the present invention will be described. The retardation film produced according to the present invention contains a transparent substrate made of a cycloolefin-based resin, a polymer of a polymerizable monomer formed on and in contact with the transparent substrate, and a liquid crystal material having homeotropic orientation. An adhesive retardation layer in which a relationship of nx = ny <nz is established between the refractive indices nx and ny in any x direction and y direction perpendicular to each other in the in-plane direction and the refractive index nz in the thickness direction; Wherein the polymerizable monomer is at least one polymerizable function selected from the group consisting of the following formulas (I), (II), (III), (IV), and (V): And a value (N / M) obtained by dividing the number N of carbon atoms constituting the polymerizable monomer by the number M of elements other than carbon and hydrogen constituting the polymerizable monomer is 3 or more. Also To become.
Since such a retardation film is the same as that described in the section “A. Retardation film”, description thereof is omitted here.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. Are included in the technical scope.

  Next, the present invention will be described more specifically by showing examples.

(1) Example 1
A liquid crystal mixture of 50% by mass of a side chain polymer represented by the following formula A and 50% by mass of a photopolymerizable liquid crystal represented by the following formula B, a photopolymerization initiator (manufactured by Ciba Specialty Chemicals, Irgacure 907, photopolymerizable compound) And a mixture obtained by adding 10% by mass of tricyclodecane dimethanol diacrylate (carbon content ratio = 4.5) as a polymerizable monomer to the above liquid crystal mixture was added to acetone: toluene = 4: By dissolving so that it might become 20 mass% of solid content in 1 mixed solution, the coating liquid for adhesive phase difference layer formation was obtained.

Next, the coating solution for forming the adhesive retardation layer is applied on a Re = 100 nm transparent substrate made of a norbornene resin (trade name: Arton, manufactured by JSR), and then dried at 100 ° C. for 1 minute. The mixture was homeotropically aligned by cooling to room temperature. Furthermore, it hardened | cured with 100 mJ / cm < ² > UV, and produced the phase difference film by forming the adhesive phase difference layer of thickness 1 micrometer on the said transparent base material.

(2) Example 2
A retardation film was produced in the same manner as in Example 1 except that 1,9-nonanediol diacrylate (carbon content ratio = 3.75) was used as the polymerizable monomer.

(3) Example 3
A liquid crystal mixture containing liquid crystal materials represented by the following formulas C, D and E, a photopolymerization initiator (manufactured by Ciba Specialty Chemicals, Irgacure 907, 5% by mass with respect to the liquid crystal mixture), and tricyclo as a polymerizable monomer Decandimethanol diacrylate (carbon content ratio = 4.5) is 10% by mass with respect to the liquid crystal mixture, and surfactant (trade name: FC-4430: manufactured by 3M Company) is 0.05% by mass with respect to the liquid crystal mixture. % Of the mixture was dissolved in an acetone: toluene = 4: 1 mixed solution so as to have a solid content of 20% by mass to obtain a coating solution for forming an adhesive retardation layer.

Next, the coating liquid for forming the adhesive retardation layer is applied onto a Re = 100 nm transparent substrate made of norbornene resin (trade name: Arton, manufactured by JSR), and then dried at 60 ° C. for 2 minutes. And homeotropic alignment. Furthermore, it hardened | cured with 100 mJ / cm < ² > UV, and produced the phase difference film by forming the adhesive phase difference layer of thickness 1 micrometer on the said transparent substrate.

(4) Example 4
A retardation film was produced in the same manner as in Example 1 except that 1,6-hexanediol acrylate (carbon content ratio = 3.0) was used as the polymerizable monomer.

(5) Comparative Example 1
A retardation film was produced in the same manner as in Example 1 except that pentaerythritol triacrylate (carbon content ratio = 1.86) was used as the polymerizable monomer.

(6) Comparative Example 2
A retardation film was produced in the same manner as in Example 3 except that neopentyl glycol diacrylate (carbon content ratio = 1.86) was used as the polymerizable monomer.

(7) Evaluation Liquid crystal orientation evaluation and adhesiveness evaluation were performed about the retardation film produced in the said Example and comparative example. In the liquid crystal orientation evaluation, nx, ny, and nz of the retardation film were calculated using an automatic birefringence measuring device KOBRA. If nx>nz> ny, it was determined that a positive C plate function was imparted. .
As a result, it was confirmed that the positive C plate function was imparted to any of the retardation films prepared in the above Examples and Comparative Examples.

In addition, the above-mentioned adhesion evaluation is performed by placing 1 mm square cuts in a grid pattern, and attaching an adhesive tape (product name: cello tape (registered trademark)) manufactured by Nichiban Co., Ltd. to the surface of the retardation layer, and thereafter adhesive tape Was peeled off and visually observed. At this time, the evaluation was performed based on the number of cells in the portion where the adhesion was not peeled / the number of cells in the region where the tape was attached.
The results are shown in Table 1.

  As shown in Table 1, although the retardation film produced in the said Example had favorable adhesiveness, the adhesiveness produced in the said comparative example was not what can endure practicality.

It is the schematic which shows an example of the retardation film of this invention. It is the schematic which shows an example of the manufacturing method of the retardation film of this invention. It is the schematic which shows a part of common liquid crystal display device typically.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Transparent substrate 2 ... Adhesive phase difference layer 2 '... Adhesive phase difference layer formation layer 10 ... Retardation film

Claims (3)

A transparent substrate made of cycloolefin resin;
A refractive index nx in any x-direction and y-direction formed in contact with the transparent substrate, containing a polymer of a polymerizable monomer and a liquid crystal material having homeotropic alignment and orthogonal to each other in an in-plane direction, and a retardation film having an adhesive retardation layer in which a relationship of nx = ny <nz is established between ny and a refractive index nz in a thickness direction,
The polymerizable monomer has at least one polymerizable functional group selected from the group consisting of the following formulas (I), (II), (III), (IV), and (V); The value obtained by dividing the number N of carbon atoms constituting the polymerizable monomer by the number M of elements other than carbon and hydrogen constituting the polymerizable monomer (N / M) is 3 or more. the film.

(In the above formula, R ¹ , R ² and R ³ represent a methyl group or hydrogen. R ⁴ represents a hydrogen, methyl group or ethyl group.)   The retardation film according to claim 1, wherein a surfactant is contained in the adhesive retardation layer. A transparent substrate made of a cycloolefin resin is used, and an adhesive retardation layer forming coating solution in which at least a polymerizable monomer and a liquid crystal material having homeotropic alignment are dissolved in a solvent is brought into contact with the transparent substrate. By coating, an adhesive retardation layer forming layer forming step for forming an adhesive retardation layer forming layer, and a polymerizable monomer contained in the adhesive retardation layer forming layer is polymerized. And a curing treatment step for forming an adhesive retardation layer by,
Adhesiveness on the transparent substrate in which a relationship of nx = ny <nz is established between the refractive indices nx and ny in the arbitrary x and y directions perpendicular to each other in the in-plane direction and the refractive index nz in the thickness direction. A phase difference film is produced by producing a phase difference film in which a phase difference layer is formed,
The polymerizable monomer has at least one polymerizable functional group selected from the group consisting of the following formulas (I), (II), (III), (IV), and (V); The value obtained by dividing the number N of carbon atoms constituting the polymerizable monomer by the number M of elements other than carbon and hydrogen constituting the polymerizable monomer (N / M) is 3 or more. A method for producing a film.

(In the above formula, R ¹ , R ² , and R ³ represent a methyl group or hydrogen. R ⁴ represents a hydrogen, a methyl group, or an ethyl group.)

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