JP2008090321A - Optical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical device constructed by curing a polymerizable liquid crystal material of which the various optical characteristics are stable even against heating during manufacture of an optical apparatus such as an image display device. <P>SOLUTION: The optical device has a support and an optical functional layer made of a cured polymerizable liquid crystal material having a predetermined liquid crystal regularity and provided on the support. The optical device is characterized in that it is subjected to a heat treatment at a predetermined temperature and in that the thickness decrease of the optical functional layer defined by (A-B)/A is 5% or less, wherein: A is the thickness of the optical functional layer after the heat treatment; and B is the thickness of the optical functional layer after the optical device is heated for 60 minutes at the heat treatment temperature. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a heat-resistant optical element in which various characteristics are stable when heat is applied.

  Conventionally, an optical element such as a retardation film or a circularly polarized light control optical element used in an image display apparatus or the like may be used by being incorporated in an image display apparatus such as a liquid crystal display apparatus. When manufacturing such an image display device, for example, it may be heated at 200 ° C. or more for forming a polyimide film used for an alignment film or for forming an ITO film as a transparent electrode. When it is used for a display used in the above, it may be heated to 100 ° C. or more due to a temperature rise caused by sunlight. Therefore, the optical element such as the above-described retardation film used in the image display device such as the liquid crystal display device is also heated at a temperature of 100 ° C. or higher and in some cases 200 ° C. or higher depending on the order of incorporation and the place of use. There was a possibility.

On the other hand, in recent years, an optical element obtained by polymerizing a polymerizable liquid crystal material has been proposed as described in, for example, JP-A-2001-100045 and JP-T-10-508882. (Patent Document 1, Patent Document 2).
Since such an optical element has an advantage that the characteristics of the liquid crystal can be fixed by polymerization and used as a film, development to various applications is expected.

  Regarding these optical elements such as a retardation film, JP-A-5-2109 discloses a stretched retardation film having excellent heat resistance (Patent Document 3), and JP-A-5-142510. Discloses an optical element made of a liquid crystalline polymer that is thermally polymerized and has excellent heat resistance (Patent Document 4). Furthermore, Japanese Patent Application Laid-Open No. 2001-133628 discloses a polarizing diffractive film made of a liquid crystal material including a polymer liquid crystal excellent in heat resistance and a crosslinkable substance (Patent Document 5).

  However, an optical element obtained by polymerizing such a polymerizable liquid crystal material has a problem that, when heated, for example, in the case of a cholesteric layer having cholesteric regularity, a shift of the central reflection wavelength occurs. It was. Therefore, as described above, when incorporated in an image display device such as a liquid crystal display device, there is a problem that it can be used only in a portion that is not heated during manufacture.

  Further, when the stretched phase difference film is 80 ° C. or higher, particularly 100 ° C. or higher, the amount of retardation changes, and thus there is a problem such as display unevenness in an in-vehicle LCD.

Japanese Patent Laid-Open No. 2001-100045 Japanese National Patent Publication No. 10-508882 JP-A-5-2109 Japanese Patent Laid-Open No. 5-142510 JP 2001-133628 A

  The present invention has been made in view of the above problems, and a polymerizable liquid crystal material having stable various optical characteristics is cured even when heated in manufacturing an optical apparatus such as an image display device. The main object of the present invention is to provide an optical element.

  In order to achieve the above object, the present invention provides, as described in claim 1, an optical function comprising a support material and a polymerizable liquid crystal material cured on the support material with a predetermined liquid crystal regularity. The optical element is heat-treated at a predetermined temperature, the film thickness of the optical functional layer after the heat treatment is A, and the optical element is again subjected to the heat treatment temperature. When the film thickness of the optical function layer after heating for 60 minutes is B, the film thickness reduction rate of the optical function layer defined by (AB) / A is 5% or less. An optical element is provided. Thus, if the reduction rate of the film thickness when heated for 60 minutes at the same temperature as the heat treatment temperature is within the above-described range, for example, if the optical element is used as a retardation plate, the retardation value and the optical element are Since the circularly polarized light control optical element can minimize the change in the central reflection wavelength, even when incorporated in various image display devices, the change in the function of the optical element should be minimized. Is possible.

  In the invention described in claim 1, as described in claim 2, it is preferable that the polymerizable liquid crystal material has a photopolymerization initiator. This is because, in order to cure the polymerizable liquid crystal material with, for example, ultraviolet rays, it is preferable to include a photopolymerization initiator for promoting polymerization. Moreover, it is because the optical functional layer formed by curing a polymerizable liquid crystal material containing a photopolymerization initiator effectively exhibits the advantages of the present invention.

  In the invention described in claim 1 or 2, as described in claim 3, the support material may be a base material having orientation ability. If an optical functional layer is formed on a substrate having orientation ability and can be used as it is, there is no need to perform a transfer process or the like, which is advantageous in terms of the process.

  The present invention also provides a support material and a retardation layer obtained by curing a polymerizable liquid crystal material on the support material with nematic regularity, smectic regularity, or cholesteric regularity. The retardation layer laminate has a retardation value of Ra after the heat treatment, the retardation layer laminate being heat-treated at a predetermined temperature, and the retardation layer laminate When the retardation value of the retardation layer after heating for 60 minutes at the heat treatment temperature is Rb, the retardation reduction rate of the retardation layer defined by (Ra−Rb) / Ra is Provided is a retardation layer laminate characterized by being 5% or less. This is because when incorporated in various image display devices and used, if the change in retardation value due to heating is about this level, it can be used without problems.

  In the invention described in claim 4, as described in claim 5, the polymerizable liquid crystal material preferably has a photopolymerization initiator and a polymerizable liquid crystal monomer. As described, it is more preferable that the polymerizable liquid crystal material having cholesteric regularity has a photopolymerization initiator, a polymerizable liquid crystal monomer, and a polymerizable chiral agent. The retardation value is a value related to the thickness of the retardation layer, and the change in the thickness of the retardation layer due to heating is presumed to depend on the amount of residue of the photopolymerization initiator. Therefore, when the photopolymerization initiator is contained in the polymerizable liquid crystal material, it is considered that the advantages of the present invention can be particularly utilized.

  In the invention described in claims 4 to 6, as described in claim 7, the support material may be a base material having orientation ability. If a retardation layer can be formed on a substrate having orientation ability and used as a retardation layer laminate as it is, there is no need to perform a transfer step or the like, which is advantageous in terms of the process.

  The present invention further provides a circularly polarized light controlling optical element having a support material and a cholesteric layer in which a polymerizable liquid crystal material is cured with cholesteric regularity on the support material. The circularly polarized light controlling optical element is heat-treated at a predetermined temperature, the central reflection wavelength of the cholesteric layer after the heat treatment is λa, and the circularly polarized light controlling optical element is again heated to the heat treatment temperature at the heat treatment temperature. A change rate of the center wavelength defined by | λa−λb | / λa when the center reflection wavelength of the cholesteric layer after heating for a minute is λb, is 5% or less. A polarization control optical element is provided. This is because, for example, when incorporated in an image display device as a color filter or the like, if the fluctuation of the central reflection wavelength due to heating is about this level, it can be used without any problem.

  In the invention described in claim 8, as described in claim 9, the polymerizable liquid crystal material has a photopolymerization initiator, a polymerizable liquid crystal monomer, and a polymerizable chiral agent. It is preferable. Although the central reflection wavelength of the cholesteric layer depends on the helical pitch, the helical pitch also changes as the film thickness changes. Therefore, it is preferable that a photopolymerization initiator is contained for the same reason as described above.

Also in this case, in the invention described in claim 8 or claim 9, as described in claim 10, the support material may be a base material having orientation ability.
If a cholesteric layer can be formed on a substrate having orientation ability and used as a circularly polarized light control optical element as it is, there is no need to perform a transfer step or the like, which is advantageous in terms of the process.

  The present invention further provides an optical element comprising: a support material; and an optical functional layer obtained by curing a polymerizable liquid crystal material with a predetermined liquid crystal regularity on the support material. On the other hand, a heat treatment method for an optical element is provided, in which heat resistance is imparted to the optical element by performing heat treatment at a predetermined temperature. By performing the heat treatment within the above-described range, it is possible to previously remove components that are removed during heating in the optical functional layer. It is also possible to increase the degree of polymerization (three-dimensional) of the polymerizable liquid crystal material. Therefore, even if the subsequent heating, that is, the heating during the manufacture of the image display device or the like is performed, it is possible to prevent the change in film thickness and the change in characteristics accompanying it, and the thermal stability of the optical functional layer can be prevented. It can be granted.

  Further, the present invention provides an optical element having a base material and an optical functional layer obtained by curing a polymerizable liquid crystal material on the base material with a predetermined liquid crystal regularity. In contrast, the present invention provides a method for heat-treating an optical element characterized by imparting heat resistance to the optical element by performing heat treatment at a temperature equal to or higher than the isotropic layer before polymerization of the polymerizable liquid crystal material. Thus, by performing heat treatment at a temperature higher than the isotropic layer before polymerization of the polymerizable liquid crystal material, molecules that are not completely polymerized (not cross-linked) in the optical element are made more stable. Therefore, even if heating is performed in the manufacture of an image display device or the like, it is possible to prevent a change in film thickness and a change in characteristics associated therewith. Can be granted.

  In the invention described in claim 11 or 12, as described in claim 13, it is preferable that the heat treatment is performed for 10 minutes to 60 minutes. This is because by performing the heat treatment for a time within this range, an optical functional layer having better thermal stability can be obtained.

  In the invention described in any one of claims 11 to 13, as described in claim 14, the polymerizable liquid crystal material preferably contains a photopolymerization initiator. This is because the change in the film thickness during the heating is considered to be related to the presence of the residue of the photopolymerization initiator present in the film as described above.

  In the invention described in claim 14, as described in claim 15, the content of the photopolymerization initiator is preferably 1% by mass or more. This is because the advantages of the present invention can be utilized particularly when the photopolymerization initiator in such an amount is contained.

  In the invention according to any one of claims 11 to 15, as described in claim 16, the temperature of the heat treatment is added in a manufacturing process of an optical device in which the optical functional layer is subsequently used. It is preferable that the temperature is within a range from a temperature to 10 ° C higher than that temperature. For example, when an optical element is used in a liquid crystal display device, components that are removed by heating are preliminarily heated at a temperature 10 ° C. higher than the temperature applied to the optical element when the liquid crystal display device is manufactured. This is because, since it has been removed, problems such as a reduction in film thickness do not occur in subsequent heating during manufacturing.

  In the invention described in any one of claims 11 to 16, as described in claim 17, the optical functional layer is a retardation layer, and the polymerizable liquid crystal material is A polymerizable liquid crystal monomer is included, and the liquid crystal regularity is preferably nematic regularity, smectic regularity, or cholesteric regularity. This is because when the optical element is a retardation layer laminate, the change in the retardation value can be minimized by performing heat treatment in advance. When the liquid crystal regularity is cholesteric regularity, the polymerizable liquid crystal material needs to contain a chiral agent.

  On the other hand, in the invention described in any one of claims 11 to 17, as described in claim 18, the optical functional layer is a cholesteric layer, and the polymerizable liquid crystal material is Further, it may contain a polymerizable liquid crystal monomer and a polymerizable chiral agent, and the liquid crystal regularity may be cholesteric regularity. As described above, when the optical element is a circularly polarized light controlling optical element, a change in the reflection center wavelength due to heating can be minimized by performing heat treatment in advance.

  In the invention described in any one of claims 11 to 16, the polymerizable liquid crystal material contains a polymerizable liquid crystal monomer as described in claim 19. The polymerizable liquid crystal monomer molecule may have a polymerizable functional group at both ends.

  Furthermore, in the invention described in claim 19, as described in claim 20, the polymerizable liquid crystal material contains a polymerizable liquid crystal monomer and a polymerizable chiral agent, and the polymerizable chiral agent The molecule may have a polymerizable functional group at both ends. As described above, if the polymerizable liquid crystal monomer molecules have polymerizable functional groups at both ends, the both ends of the adjacent monomer molecules are polymerized (crosslinked) in a three-dimensional network, resulting in more heat resistance. High optical element can be obtained.

  Since the present invention is an optical element having a very small reduction rate of film thickness when heated at 100 ° C. for 60 minutes, for example, when the optical element is used as a retardation plate, the retardation value is controlled and the optical element is circularly polarized. If it is an optical element, the change of the center reflection wavelength can be minimized. Therefore, even when used in various image display devices, it is possible to minimize the change in the function of the optical element, so that various applications can be developed.

  Hereinafter, after describing the optical element of the present invention, a heat treatment method for obtaining such an optical element will be described.

<Optical element>
The optical element of the present invention is an optical element having a support material and an optical functional layer obtained by curing a polymerizable liquid crystal material on the support material with a predetermined liquid crystal regularity, and the optical element is The film thickness of the optical functional layer after being heat-treated at a predetermined temperature, the film thickness of the optical functional layer after the heat treatment being A, and the optical element being heated again at the heat treatment temperature for 60 minutes. Is B, the film thickness reduction rate of the optical function layer defined by (AB) / A is 5% or less.

  In the present invention, as described above, when the rate of decrease in the film thickness of the optical functional layer is within the above-described range when the film is heated again at the same temperature as the heat treatment temperature for 60 minutes, various variations caused by film thickness variations occur. Therefore, it can be used in a manufacturing process in which heat is highly likely to be applied, so that it can be used in various applications. Here, when a polymer stretched film or the like is used as a base material as described below, the predetermined heat treatment temperature needs to be lower than the temperature at which the base material softens (deforms). Therefore, it is generally about 80 to 120 ° C. On the other hand, when a glass substrate or the like is used as the base material, thermal decomposition of the optical functional layer formed on the base material occurs at a temperature lower than the temperature at which the base material is deformed. It is about -240 degreeC.

  The reason why the decrease rate due to heating of the film thickness of the optical functional layer in the optical element of the present invention is small is presumed to be as follows.

  That is, a conventional optical element using a polymerizable liquid crystal material is polymerized and fixed in a state where the polymerizable liquid crystal material has a predetermined liquid crystal structure. In a state where the polymerizable liquid crystal material is only polymerized into a polymer, in addition to the polymer having this liquid crystal structure, for example, a polymerization reaction such as a photopolymerization initiator residue and a product derived from the photopolymerization initiator. There may be impurities or photopolymerization initiator residues produced during the process. Since such impurities are not chemically bonded to the polymer main chain, there is a high possibility that they will escape from the optical functional layer when heated after polymerization. Thus, if the substance in the optical functional layer is removed during heating, the film thickness of the optical functional layer is naturally reduced.

  In the present invention, as will be described later, the optical functional layer is heated in advance at a predetermined temperature to remove impurities present in the optical functional layer in advance, and thus the impurities are removed in advance. Therefore, even if heat is applied after that, the reduction of the film thickness can be within a range where there is no problem.

  The optical element of the present invention has the following actions and effects because there is little decrease in film thickness due to heating.

  That is, the film thickness of the optical functional layer is, for example, a value related to the retardation value when the optical functional layer is a retardation layer, the optical element is a circular polarization control optical element, and the optical functional layer is a cholesteric layer. (In the present invention, a layer in which a liquid crystal material having cholesteric regularity is fixed is referred to as a cholesteric layer.) In this case, the central reflection wavelength of the cholesteric layer is a film thickness (spiral pitch). The spiral pitch also changes as the film thickness changes.

  Therefore, when the film thickness of the optical functional layer is greatly reduced by heating, such an important optical characteristic greatly varies. Thus, when used in an image display device, the expected optical characteristics cannot be obtained, making it difficult to use. In the optical element of the present invention, since the reduction rate of the film thickness by heating is within the above-described range, it is possible to greatly reduce the fluctuation due to heating of the optical characteristics of the optical element described above. Even in an image display device or the like that is highly likely to be heated, an optical element that can be sufficiently used can be obtained.

  Hereinafter, such an optical element will be described for each element.

1. Support material The support material as used in the field of this invention shows the to-be-transferred material, when the base material which has orientation ability, or when an optical function layer is transcribe | transferred by the transfer process.

(Substrate having orientation ability)
The optical element of the present invention is obtained by forming an optical functional layer obtained by curing a polymerizable liquid crystal material with a predetermined liquid crystal regularity on a substrate having alignment ability.

  Examples of such a substrate having orientation ability include a case where the substrate itself has orientation ability, and a case in which an orientation film is formed on a transparent substrate and functions as a substrate having orientation ability. Can do. Hereinafter, each will be described as a first embodiment and a second embodiment.

a. First Embodiment This embodiment is an embodiment in which the base material itself has orientation ability, and specifically includes a case where the base material is a stretched film. By using a stretched film in this way, it is possible to align the liquid crystal material along the stretched direction.
Therefore, since the preparation of the base material can be performed simply by preparing a stretched film, it has an advantage that it is extremely simple in terms of the process. As such a stretched film, a commercially available stretched film can be used, and stretched films of various materials can be formed as necessary.

  Specifically, polycarbonate polymers, polyester polymers such as polyarylate and polyethylene terephthalate, polyimide polymers, polysulfone polymers, polyethersulfone polymers, polystyrene polymers, polyolefins such as polyethylene and polypropylene Film made of thermoplastic polymer such as polymer based polymer, polyvinyl alcohol polymer, cellulose acetate polymer, polyvinyl chloride polymer, polymethyl methacrylate polymer, or film made of liquid crystal polymer. it can.

  In the present invention, among them, a polyethylene terephthalate (PET) film is preferably used from the viewpoints of a wide range of stretch ratio and availability.

  The stretch ratio of the stretched film used in the present invention is not particularly limited as long as the stretch ratio is such that the orientation ability can be exhibited. Therefore, even if it is a biaxially stretched film, it can be used as long as the stretch ratio differs between the two axes.

  This stretch ratio varies greatly depending on the material used, and is not particularly limited, but generally a stretch ratio of about 150% to 300% can be used, preferably 200% to 250%. Is used.

b. Second Embodiment A second embodiment is an embodiment in which the base material having the alignment ability is composed of a transparent substrate and an alignment film formed on the transparent substrate.

  This embodiment has an advantage that a relatively wide range of alignment directions can be selected by selecting an alignment film. By selecting the kind of the coating liquid for forming the alignment film applied on the transparent substrate, various alignment directions can be realized, and more effective alignment can be performed.

  As the alignment film used in the present embodiment, an alignment film usually used in a liquid crystal display device or the like can be suitably used. In general, a film obtained by rubbing a polyimide-based or polyvinyl alcohol-based alignment film is preferable. Used for. It is also possible to use a photo-alignment film.

  Further, the transparent substrate used in the present embodiment is not particularly limited as long as it is formed of a transparent material. For example, the flexible substrate such as quartz glass, Pyrex (registered trademark) glass, synthetic quartz plate, etc. A transparent rigid material having no flexibility, or a transparent flexible material having flexibility such as a transparent resin film and an optical resin plate can be used.

(Transfer material)
The transfer material used in the present invention is appropriately selected according to the use of the optical element, but since it is generally an optical element, a transparent material, that is, a transparent substrate is preferably used.

  Since this transparent substrate is the same as that described in the above-mentioned “base material having orientation ability”, description thereof is omitted here.

2. Optical functional layer The optical element of the present invention comprises an optical functional layer formed by curing a polymerizable liquid crystal material having a predetermined liquid crystal regularity on the substrate. Such an optical functional layer is made of a polymerizable liquid crystal material constituting a polymer having liquid crystal regularity. In addition, the residue of additives, such as a photoinitiator contained in the coating liquid for liquid crystal layer formation mentioned later may be contained. Hereinafter, these will be described.

(Polymerizable liquid crystal material)
Examples of the polymerizable liquid crystal material used in the present invention include a polymerizable liquid crystal monomer, a polymerizable liquid crystal oligomer, and a polymerizable liquid crystal polymer. As such a polymerizable liquid crystal material, a material having nematic regularity or smectic regularity is usually used, but is not particularly limited to this, and the polymerizable liquid crystal material has cholesteric regularity. It may be. Further, when cholesteric regularity is required depending on the optical element, and the polymerizable liquid crystal material itself exhibits nematic regularity or smectic regularity, a polymerizable chiral agent may be further used to impart cholesteric regularity. Good. Each will be described below.

(1) Polymerizable liquid crystal material Examples of the polymerizable liquid crystal material used in the present invention include a polymerizable liquid crystal monomer, a polymerizable liquid crystal oligomer, and a polymerizable liquid crystal polymer as described above. Such a polymerizable liquid crystal material is not particularly limited as long as it is a polymerizable liquid crystal material capable of forming a liquid crystal phase having nematic regularity, smectic regularity, or cholesteric regularity when a liquid crystal phase is formed only by these. However, it is preferable to have polymerizable functional groups at both ends of the molecule in order to obtain an optical element with good heat resistance.

  As an example of such a polymerizable liquid crystal material, for example, compound (I) represented by the following general formula (1) and the following compounds can be mentioned. As the compound (I), it is also possible to use a mixture of two compounds included in the general formula (1).

化合物（Ｉ）を表わす一般式（１）において、Ｒ¹及びＲ²はそれぞれ水素又はメチル基を示し、Ｘは、塩素又はメチル基であることが好ましい。また、化合物（Ｉ）のスペーサーであるアルキレン基の鎖長を示すａ及びｂは、２〜９の範囲であることが液晶性を発現させる上で好ましい。 As the polymerizable liquid crystal material, a compound included in the general formula (1) or two or more of the following compounds may be mixed and used.

In the general formula (1) representing the compound (I), R ¹ and R ² each represent hydrogen or a methyl group, and X is preferably a chlorine or methyl group. Moreover, it is preferable that a and b which show the chain length of the alkylene group which is a spacer of compound (I) are in the range of 2-9 in order to develop liquid crystallinity.

  In the example described above, an example of a polymerizable liquid crystal monomer has been described. However, in the present invention, a polymerizable liquid crystal oligomer, a polymerizable liquid crystal polymer, or the like can be used. As such a polymerizable liquid crystal oligomer and a polymerizable liquid crystal polymer, those conventionally proposed can be appropriately selected and used.

(2) Chiral agent In the present invention, when the optical element is a circular polarization control optical element, that is, the optical functional layer is a cholesteric layer and the polymerizable liquid crystal material exhibits nematic regularity or smectic regularity, In addition to the liquid crystalline material, it is necessary to add a chiral agent.

カイラル剤（ＩＩ）を表わす一般式（２）、（３）又は（４）において、Ｒ⁴は水素又はメチル基を示す。Ｙは上記に示す式（ｉ）〜（ｘｘｉｖ）の任意の一つであるが、なかでも、式（ｉ），（ｉｉ），（ｉｉｉ），（ｖ）及び（ｖｉｉ）の何れか一つであることが好ましい。また、アルキレン基の鎖長を示すｃ及びｄは、２〜９の範囲であることが好ましい。ｃ及びｄが、２未満または１０以上であると、液晶性が発現しにくくなる。 The polymerizable chiral agent used in the present invention is a low molecular compound having an optically active site, and means a compound having a molecular weight of 1500 or less. The chiral agent is mainly used for the purpose of inducing a helical pitch in the positive uniaxial nematic regularity expressed by the compound (I). As long as this purpose is achieved, the compound (I) and the above compound are compatible with each other in a solution state or in a molten state, and the liquid crystal property of the polymerizable liquid crystal material capable of taking the nematic regularity is not impaired. As long as it can induce a helical pitch, the kind of low molecular compound as a chiral agent shown below is not particularly limited, but an optical element having good heat resistance can be obtained by having polymerizable functional groups at both ends of the molecule. Preferred above. It is essential that the chiral agent used for inducing a helical pitch in the liquid crystal has at least some chirality in the molecule. As the chiral agent having an optically active site to be contained in the liquid crystalline composition of the present invention, it is preferable to select a chiral agent having a large effect of inducing a helical pitch. Specifically, the general formulas (2), (3 ) Or (4), it is preferable to use a low molecular compound (II) having axial asymmetry in the molecule.

In the general formula (2), (3) or (4) representing the chiral agent (II), R ⁴ represents hydrogen or a methyl group. Y is any one of formulas (i) to (xxiv) shown above, and among them, any one of formulas (i), (ii), (iii), (v), and (vii) It is preferable that Moreover, it is preferable that c and d which show the chain length of an alkylene group are the range of 2-9. When c and d are less than 2 or 10 or more, liquid crystallinity is hardly exhibited.

  The amount of the chiral agent blended in the polymerizable liquid crystal material of the present invention is determined in consideration of the helical pitch inducing ability and the cholesteric property of the finally obtained circularly polarized light controlling optical element. Specifically, although it varies greatly depending on the polymerizable liquid crystal material to be used, it is selected in the range of 1 to 20 parts by mass per 100 parts by mass of the total amount of the polymerizable liquid crystal material. When the blending amount is less than the above range, the polymerizable liquid crystal material may not be provided with sufficient cholesteric property. There is a risk of affecting.

  In the present invention, it is not essential that such a chiral agent has polymerizability. However, in consideration of the thermal stability and the like of the obtained optical functional layer, it is preferable to use a polymerizable chiral agent that can be polymerized with the above-described polymerizable liquid crystal material and fix the cholesteric regularity. In particular, it is preferable to have a polymerizable functional group at both ends of the molecule in order to obtain an optical element having good heat resistance.

(Photopolymerization initiator)
In the present invention, it is preferable that a photopolymerization initiator is added to the polymerizable liquid crystal material described above. For example, when a polymerizable liquid crystal material is polymerized by electron beam irradiation, a photopolymerization initiator may be unnecessary, but in the case of curing by, for example, ultraviolet (UV) irradiation, which is generally used, This is because the photopolymerization initiator is used for promoting the polymerization.

  In addition to the photopolymerization initiator, it is also possible to add a sensitizer as long as the object of the present invention is not impaired.

  Such an addition amount of the photopolymerization initiator can be generally added to the polymerizable liquid crystal material of the present invention in the range of 0.5 to 10% by mass.

3. Liquid Crystal Regularity In the present invention, an optical functional layer is used in which the polymerizable liquid crystal material is cured with a predetermined liquid crystal regularity.

  Here, the liquid crystal regularity includes nematic regularity, smectic regularity, and cholesteric regularity. When the optical element is a retardation layer laminate, the optical functional layer has nematic regularity or smectic regularity. On the other hand, when the optical element is a circular polarization control optical element, it has cholesteric regularity.

  The regularity is basically determined by the liquid crystal regularity exhibited by the polymerizable liquid crystal material used and whether or not a chiral agent is used.

  Such liquid crystal regularity forms a liquid crystal layer composed of the above-described polymerizable liquid crystal material and a polymerizable chiral agent added as necessary on a substrate having alignment ability, thereby improving the alignment ability of the substrate. It is obtained by orienting along. And it can be hardened by irradiating actinic radiation in the state which has liquid crystal regularity, and it can be set as the optical functional layer hardened in the state which has liquid crystal regularity.

4). Reduction rate of optical functional layer by heating The feature of the present invention is that when the optical functional layer as described above is heated for 60 minutes at the same temperature as the temperature at which the optical element is heat-treated, the reduction rate of the film thickness is 5% or less, preferably 3% or less, particularly preferably 1% or less. If the reduction rate is within this range, for example, in the case where the optical element is a retardation plate, or in the case of a circular polarization control optical element, the retardation value or central reflection wavelength, which is an important optical characteristic, Even when heated in the manufacturing process of an image display apparatus or the like using these optical elements, there is no significant change. Therefore, the optical element of the present invention can be used even when it is heated in the process after the optical element is attached.

5. Specific Examples of Optical Element Specific examples of the optical element of the present invention include a retardation layer laminate when the optical functional layer is a retardation layer and a circularly polarized light controlling optical element in which the optical functional layer is a cholesteric layer. it can. Each will be described below.

(Retardation layer laminate)
When the optical element is a retardation layer laminate, in the present invention, the support material and the polymerizable liquid crystal material on the support material are cured with nematic regularity, smectic regularity, or cholesteric regularity. A retardation layered body having a retardation layer, wherein a change in the retardation value of the retardation layer due to heating is 5% or less when heated at the same temperature as a predetermined heat treatment temperature for 60 minutes, preferably Is a retardation layer laminate having a content of 3% or less, particularly 1% or less.

  As described above, in the optical element of the present invention, since the variation in film thickness when heat is applied is extremely small, when the optical element is a retardation layer laminate, the retardation value when heat is applied. It is possible to make the fluctuation of the extremely small.

  In the present invention, since the fluctuation of the retardation value when heat is applied in this way is extremely small, it is necessary to perform a heat treatment, for example, for forming an ITO film after incorporating the retardation layer laminate. Even in such a case, it can be used. Therefore, it has the advantage that the range of use of the retardation layer laminate of the present invention can be greatly expanded.

  As such a liquid crystal material used for the retardation layer, a material obtained by applying the above-described polymerizable liquid crystal monomer and a photopolymerization initiator in a state of being dissolved in a solvent and curing it is preferably used. As the polymerizable liquid crystal monomer and photopolymerization initiator that can be used in this case, those described above can be used.

  Since other configurations are the same as those described above, description thereof is omitted here.

(Circular polarization control optical element)
In the case where the optical element is a circular polarization control optical element, in the present invention, a circularly polarized light having a support material and a cholesteric layer in which a polymerizable liquid crystal material is cured with cholesteric regularity on the support material. The control optical element, wherein the change in the central reflection wavelength of the cholesteric layer is not more than 5%, preferably not more than 3%, particularly not more than 1% when heated at the same temperature as the predetermined heat treatment temperature for 60 minutes. A certain circular polarization control optical element can be mentioned.

  Similarly, in this case, since the change in the film thickness is related to the change in the central reflection wavelength of the cholesteric layer, when the optical element is a circularly polarized light control optical element, heat is generated when the image display device is manufactured. Even if added, the fluctuation of the central reflection wavelength can be made extremely small.

  In such a circularly polarized light control optical element, since the fluctuation of the central reflection wavelength at the time of heating is extremely small as described above, the circularly polarized light control optical element, specifically, after being incorporated into the image processing apparatus as a color filter, For example, it can be used even in the case where heat treatment must be performed to form an ITO film. Therefore, it has an advantage that the range of use of the circularly polarized light control optical element can be extremely widened.

  As such a liquid crystal material used for the cholesteric layer of the circular polarization control optical element, the above-described polymerizable liquid crystal monomer, polymerizable chiral agent, and photopolymerization initiator are applied in a state of being dissolved in a solvent. Those obtained by curing are preferably used. As the polymerizable liquid crystal monomer, polymerizable chiral agent and photopolymerization initiator that can be used in this case, those described above can be used.

  Since other configurations are the same as those described above, description thereof is omitted here.

<Heat treatment method>
The optical element heat treatment method of the present invention is applied to an optical element having a base material and an optical functional layer obtained by curing a polymerizable liquid crystal material with a predetermined liquid crystal regularity on the base material. It is characterized by imparting heat resistance to the optical element by performing a heat treatment at a temperature within the range of, or by performing a heat treatment at a temperature higher than the isotropic layer before polymerization of the polymerizable liquid crystal material. . In this case, the heat treatment time is preferably 10 minutes to 60 minutes. By performing such heat treatment, a liquid crystal component or a chiral component that is not cured or does not form a sufficient three-dimensional network structure can be moved to a stable state (position) in the layer.

According to the heat treatment method for an optical element of the present invention, heat treatment is performed in advance at a predetermined temperature, and thus impurities in the optical functional layer are removed at this time. Therefore, when heating is performed after that, that is, for example, in the case where the heating is performed to form a transparent electrode after attaching the optical element subjected to the heat treatment of the present invention in the image processing apparatus, Since the heat treatment is performed in advance, the film thickness of the optical element does not change, and as a result, the various optical functions related to the film thickness do not change.
Therefore, when the optical element subjected to such heat treatment is attached to an image processing apparatus or the like, there are no restrictions on the attachment position and the attachment timing, so the degree of freedom in manufacturing the image processing apparatus and the freedom of product design are reduced. The advantage is that the degree can be greatly improved.

  Hereinafter, a method for producing an optical element of the present invention including such a heat treatment method will be described.

  FIG. 1 shows an example of a method for producing an optical element of the present invention.

  In this example, first, a base material 3 having an orientation ability in which an orientation film 2 is formed on a transparent substrate 1 is formed (base material preparation step, see FIG. 1A).

  Next, a coating liquid for forming a liquid crystal layer in which a polymerizable liquid crystal material and a photopolymerization initiator are dissolved in a solvent is applied onto the base material 3 having the alignment ability, and the solvent is dried and removed. The liquid crystal layer 4 is formed by maintaining a temperature at which a phase is exhibited (liquid crystal layer forming step, see FIG. 1B). This liquid crystal layer has liquid crystal regularity by the action of the alignment film 2.

  Then, by irradiating the liquid crystal layer 4 having the liquid crystal regularity with ultraviolet light 5, the polymerizable liquid crystal material in the liquid crystal layer is polymerized by radicals generated from the photopolymerization initiator, and the liquid crystal layer 4 is optically It is set as the functional layer 6 (refer to an optical functional layer formation process, FIG.1 (c) and (d)).

  Next, the optical element 8 having the optical functional layer 6 formed on the base material 3 in this way is heated at a predetermined temperature in, for example, an oven, thereby applying heat 7 and performing heat treatment (heat treatment process, FIG. 1 (e)).

  As a result, heat treatment is applied, and an optical element 8 in which dimensional stability by heating and various optical functions associated therewith can be obtained (see FIG. 1 (f)).

  Hereinafter, the manufacturing method for manufacturing such an optical element of the present invention will be described, and the heat treatment method of the present invention will be described in detail therein.

1. Substrate preparation step In producing the optical element of the present invention, a substrate having orientation ability is first prepared. As the base material having such orientation ability, the base material itself has orientation ability, and the base material having orientation ability when the orientation film 2 is formed on the transparent substrate 1 as shown in FIG. 3 can function. Since these are the same as those described in the section <Optical element> above, description thereof is omitted here.

2. Liquid Crystal Layer Forming Step In the present invention, next, as shown in FIG. 1B, the liquid crystal layer 4 is formed on the base material 3 having the alignment ability.

  The liquid crystal layer in the present invention is formed of a polymerizable liquid crystal material and is not particularly limited as long as it is a layer capable of adopting liquid crystal phases having various liquid crystal regularities.

  Examples of a method for forming such a liquid crystal layer include the following methods. That is, a liquid crystal layer is formed by applying a liquid crystal layer forming coating solution in which a polymerizable liquid crystal material such as a polymerizable monomer, a chiral agent, and further a photopolymerization initiator and the like are dissolved in a normal solvent. A working layer is formed.

  In this case, examples of the coating method include a spin coating method, a roll coating method, a slide coating method, a printing method, a dip pulling method, a curtain coating method (die coating method), and the like.

  After forming the liquid crystal forming layer in this way, the liquid crystal layer having various liquid crystal regularities is formed by removing the solvent. As a method for removing the solvent at this time, for example, removal under reduced pressure or removal by heating, or a combination of these is performed.

  In the present invention, the method for forming the liquid crystal layer is not limited to the method using the liquid crystal layer forming coating liquid described above, and a dry film made of a liquid crystal material is laminated on a substrate having orientation ability, A method of imparting liquid crystal regularity by heating this may be used. However, in the present invention, it can be said that the method using the liquid crystal layer forming coating liquid described above is a preferable method from the viewpoint of easiness in the process.

  The polymerizable liquid crystal material, chiral agent, and photopolymerization initiator used in the liquid crystal layer forming coating solution are the same as those described in the above “optical element”, and thus the description thereof is omitted here. Hereinafter, the solvent and other additives used in the liquid crystal layer forming coating solution will be described.

(solvent)
The solvent used in the liquid crystal layer-forming coating solution may be a solvent that can dissolve the above-described polymerizable liquid crystal material and the like and that does not inhibit the alignment ability on the substrate having alignment ability. There is no particular limitation.

  If only a single type of solvent is used, the solubility of the polymerizable liquid crystal material or the like may be insufficient, or the substrate having alignment ability may be eroded as described above. However, this inconvenience can be avoided by using a mixture of two or more solvents. The concentration of the solution depends on the solubility of the liquid crystalline composition and the film thickness of the circular polarization control optical element to be produced, but cannot be defined unconditionally, but is usually adjusted in the range of 5 to 60% by mass.

  In addition, a surfactant or the like can be added to the liquid crystal layer forming coating solution in order to facilitate application.

  The amount of the surfactant added depends on the type of the surfactant, the type of the polymerizable liquid crystal material, the type of the solvent, and the type of the substrate having the alignment ability to apply the solution, but usually the liquid crystal contained in the solution. It is in the range of 0.01 to 1% by mass of the composition.

3. Optical Functional Layer Forming Process In the present invention, the liquid crystal layer has the liquid crystal regularity by irradiating the active liquid crystal layer with the active liquid crystal layer mainly composed of the polymerizable liquid crystal material formed in the liquid crystal layer forming process. By curing in such a state, optical functional layers having various optical functions can be formed.

  The actinic radiation irradiated at this time is not particularly limited as long as it is a radiation capable of polymerizing a polymerizable liquid crystal material, a polymerizable chiral agent, or the like, but is usually irradiated with a wavelength of 250 to 450 nm. Light is used.

  Irradiation intensity is appropriately adjusted according to the composition of the polymerizable liquid crystal material forming the liquid crystal layer and the amount of photopolymerization initiator.

4). Transfer step In the present invention, if necessary, after the optical functional layer forming step, a step of transferring the optical functional layer formed on the substrate having the orientation ability onto a transfer material is included. May be.

  This is because when the optical functional layer is used in combination with other layers, or the optical functional layer is preferably formed on a non-flexible substrate, it is desired to use it on the surface of the flexible film in use. It is performed as needed.

  The transfer is performed by bringing the surface of the transfer material into contact with the surface of the optical functional layer formed in the optical functional layer forming step described above (see FIGS. 1B and 1C).

  As a transfer method at this time, for example, an adhesive layer is formed in advance on the surface of the material to be transferred or the surface of the optical function layer, and a method of transferring by this adhesive force, an alignment film on the substrate is made easy to peel. The method etc. which are put are mentioned.

  More effective methods include a method in which the surface hardness of the surface of the optical functional layer on which the material to be transferred comes into contact is lower than the surface hardness of the base material side, and transfer is performed in this state. Examples of the method include forming a layer so that the residual double bond ratio of the surface of the transfer material side of the layer is higher than that of the substrate side, and performing transfer in this state. As described above, as a method of forming the polymerization degree on the surface side in the optical functional layer lower than the polymerization degree on the substrate side, the above-described polymerization is performed using the above-described polymerization initiator having an oxygen dependency in which the polymerization rate decreases in the presence of oxygen. Examples thereof include a method of polymerizing under a condition that oxygen is used only on the surface side and used for a conductive liquid crystal material.

  The transfer material used in this step is appropriately selected according to the use of the optical element to be used, but since it is generally an optical element, a transparent material, that is, a transparent substrate is preferably used. It is done.

  Since this transparent substrate is the same as that described in the above-mentioned “base material having orientation ability”, description thereof is omitted here.

5. Heat treatment step The present invention is characterized in that a heat treatment step is performed after the optical functional layer formation step, and the heat treatment method for an optical element of the present invention includes the heat treatment method in this step.

  That is, the heat treatment method for an optical element of the present invention is performed at a predetermined temperature with respect to an optical element having the above-described support material and the optical function layer formed on the support material by the above-described optical function layer forming step. Heat treatment is performed, and as described above, when a polymer stretched film or the like is used as the substrate, the heat treatment temperature is about 80 to 120 ° C. A more preferable temperature is in the range of 90 ° C to 120 ° C, and more preferably in the range of 90 ° C to 110 ° C. On the other hand, when a glass substrate or the like is used as the base material, the heat treatment temperature is about 180 ° C to 240 ° C. More preferably, it is in the range of 190 ° C to 230 ° C, and more preferably in the range of 200 ° C to 220 ° C.

  The above temperature is usually determined in consideration of the heating temperature applied when manufacturing an image processing apparatus, for example, when forming an ITO electrode or when forming a polyimide film as an alignment film. That is, the optical element to be heat-treated is required to have stable film thickness, and thus various functions of the optical element related to the film thickness, at the temperature applied to the above-described manufacturing process of the image processing apparatus. Therefore, it is preferable that the heat treatment is performed at least between a temperature applied to the manufacturing process of the image processing apparatus in which the optical element is used and a temperature at least 10 ° C. higher than that.

  In the present invention, it is preferable to perform the heat treatment at a temperature as described above for 10 minutes to 60 minutes, preferably 15 minutes to 45 minutes, particularly 20 minutes to 40 minutes.

  The heat treatment time may be a time enough to remove the internal impurities as described above, and the heat treatment is performed within the above-described range from this viewpoint.

  Such heat treatment can be performed using a general heat treatment apparatus such as an oven.

  In the present invention, the polymerizable liquid crystal material preferably contains a photopolymerization initiator. In the present invention, as described above, the optical function during heating is prevented by preventing a decrease in film thickness due to removal of impurities that do not have a chemical bond with the main chain, present in the optical functional layer during heating. The change in the thickness of the functional layer is minimized. Therefore, it is because the advantage of the heat treatment method of the present invention can be maximized when the residue such as a photopolymerization initiator is present in the optical functional layer in advance.

  Such a heat treatment method is particularly effective in a retardation laminate in which the optical functional layer is a retardation layer. If the thickness of the retardation layer varies due to heating in the manufacturing process of the image display device, the retardation value of the retardation layer varies greatly. If the retardation value of the retardation layer fluctuates in this way, it becomes a big problem in optical design, and such a retardation layer laminate in which the retardation value fluctuates cannot usually be used.

  According to the heat treatment method of the present invention, since the heat treatment as described above is performed in advance, for example, even when heat is applied to the retardation layer in the manufacturing process of the imaging device, the heat treatment is performed in advance. Fluctuation is minimal. Therefore, even when heat is applied in the manufacturing process, it can be used, and there is an advantage that the use as a retardation layer laminate is greatly expanded.

  The above heat treatment method is also particularly effective for a circularly polarized light control optical element in which the optical functional layer is a cholesteric layer. In such a cholesteric layer, the central reflection wavelength depends on the film thickness. Therefore, as with the above-described retardation layer, the central reflection wavelength, which is an important optical characteristic, does not vary even when heated at the time of manufacture, so the use as a circularly polarized light control optical element is greatly expanded. This is because it has advantages.

  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.

  The following examples further illustrate the invention.

・カイラル剤：下記化学式（６）に示す化合物のメソゲン両端にスペーサーを介して、アクリレートを設け、重合可能にした重合性カイラル剤

・光重合開始剤：チバスぺシャリティケミカルズ社製のＩＲＧ９０７（商品名） （配向膜の調製） A. Cholesteric layer (Preparation of coating liquid for liquid crystal layer formation)
Coating for forming a liquid crystal layer by dissolving a powder obtained by mixing a polymerizable liquid crystal material, a chiral agent, and a photopolymerization initiator in a ratio of 100: 5: 5 (mass%) in toluene so as to be 30 mass%. A liquid was prepared. The following were used as the polymerizable liquid crystal material, the chiral agent, and the photopolymerization initiator.
Polymerizable liquid crystal material: a polymerizable liquid crystal monomer represented by the following chemical formula (5) having a polymerizable functional group at the terminal and exhibiting nematic liquid crystal properties at 50 ° C. to 100 ° C.

-Chiral agent: a polymerizable chiral agent in which an acrylate is provided at both ends of a mesogen of a compound represented by the following chemical formula (6) via a spacer to enable polymerization.

Photopolymerization initiator: IRG907 (trade name) manufactured by Ciba Specialty Chemicals (preparation of alignment film)

  Next, a 0.7 mm thick glass substrate is spin-coated with an alignment film solution containing polyimide as a main component, and after the solvent is evaporated, post-baking is performed at 200 ° C., and the alignment film is rubbed by a known method. Produced.

  Further, an alignment film solution containing polyvinyl alcohol as a main component was bar-coated on a 75 μm-thick TAC film, the solvent was evaporated, post-baked at 100 ° C., and rubbed by a known method to prepare an alignment film.

(Formation of cholesteric layer)
The liquid crystal layer forming coating solution was spin-coated on the polyimide alignment film. Next, after evaporating the solvent, the liquid crystal molecules are aligned at 80 ° C. for 3 minutes, and after confirming that the selective reflection specific to the cholesteric structure is exhibited, UV irradiation is performed to form a cholesteric layer. Sample 1 was prepared.

  The liquid crystal forming coating solution was bar-coated on the polyvinyl alcohol alignment film. Next, after evaporating the solvent, the liquid crystal molecules are aligned at 80 ° C. for 3 minutes, and after confirming that the selective reflection specific to the cholesteric structure is exhibited, UV irradiation is performed to form a cholesteric layer. Sample 2 was prepared.

  The sample 1 thus obtained was heat-treated at 200 ° C. for 60 minutes, then naturally cooled to room temperature and allowed to stand for 1 day (Example 1), and a sample not subjected to heat treatment (Comparative Example 1) ) Was adjusted.

  Sample 2 was heat treated at 100 ° C. for 60 minutes, and then a sample that was naturally cooled to room temperature and allowed to stand for 1 day (Example 2) and a sample that was not subjected to heat treatment (Comparative Example 2) were prepared. .

(Evaluation)
The samples of Example 1 and Comparative Example 1 were heated at 200 ° C. for 60 minutes, the selective reflection center wavelength of each sample before and after heating was measured, and the change rate of the center wavelength was calculated. The following results were obtained.
-Example 1 1% fluctuation toward short wavelength side-Comparative Example 1 6% fluctuation toward short wavelength side

Further, the samples of Example 2 and Comparative Example 2 were heated at 100 ° C. for 60 minutes, and the change rate of the center wavelength of each sample was calculated in the same manner as described above, and the following results were obtained.
-Example 2 1% fluctuation toward short wavelength side-Comparative Example 2 6% fluctuation toward short wavelength side

B. Retardation layer 1
(Preparation of liquid crystal phase forming coating solution and alignment film)
A liquid crystal layer-forming coating solution was prepared in the same manner as A described above except that the chiral liquid crystal material and the photopolymerization initiator were changed to 100: 5 (mass%) without using a chiral agent. The alignment film was also adjusted in the same manner as A above.

(Formation of retardation layer)
The liquid crystal layer forming coating solution was spin-coated or bar-coated on the alignment film. Next, after evaporating the solvent, the liquid crystal molecules were nematically aligned at 80 ° C. for 3 minutes and then irradiated with UV for polymerization to form a retardation layer, thereby preparing Samples 3 and 4.

  The sample 3 having the nematic structure thus obtained was heat-treated at 200 ° C. for 60 minutes, then naturally cooled to room temperature and allowed to stand for one day (Example 3), and a sample not subjected to heat treatment (Comparative Example 3) was prepared, and Sample 4 was heat-treated at 100 ° C. for 60 minutes, and then naturally cooled to room temperature and allowed to stand for 1 day (Example 4). A sample (Comparative Example 4) was prepared.

(Evaluation)
When the samples of Example 3 and Comparative Example 3 were heated at 200 ° C. for 60 minutes, the retardation value of each sample before and after heating was measured, and the rate of change of the retardation value before and after heating was calculated. The following results were obtained.
Example 3 Variation of 1% retardation value Comparative Example 3 Variation of 6% retardation value

Further, the samples of Example 4 and Comparative Example 4 were heated at 100 ° C. for 60 minutes, and the change rate of the retardation value of each sample was calculated in the same manner as described above. The following results were obtained.
Example 4 Variation of 1% retardation value Comparative Example 4 Variation of 6% retardation value

C. Phase difference layer 2
(Preparation of liquid crystal phase forming coating solution and alignment film)
A liquid crystal layer-forming coating solution was prepared in the same manner as A described above except that the polymerizable liquid crystal material, the chiral agent, and the photopolymerization initiator were in a ratio of 100: 15: 5 (mass%).
The alignment film was also adjusted in the same manner as A above.

(Formation of retardation layer)
The liquid crystal layer forming coating solution was spin-coated on the polyimide alignment film. Next, after evaporating the solvent, liquid crystal molecules were aligned at 80 ° C. for 3 minutes and polymerized by irradiating UV to form a cholesteric layer, thereby preparing Sample 5.
Since the liquid crystal layer coating solution contains more chiral agent components than the liquid crystal forming coating solution used in Example 1, the selective reflection center wavelength of the prepared sample 5 was in the ultraviolet region. The retardation layer prepared in this way functioned as a negative retardation compensation plate.

  The liquid crystal forming coating solution was bar-coated on the polyvinyl alcohol alignment film. Next, after evaporating the solvent, the liquid crystal molecules were aligned at 80 ° C. for 3 minutes and polymerized by irradiation with UV to form a cholesteric layer, thereby preparing Sample 6. Also in sample 6, the selective reflection center wavelength was in the ultraviolet region.

  The sample 3 having the nematic structure thus obtained was heat-treated at 200 ° C. for 60 minutes, then naturally cooled to room temperature and allowed to stand for one day (Example 5), and a sample not subjected to heat treatment (Comparative Example 5) was prepared, and Sample 6 was also heat-treated at 100 ° C. for 60 minutes, and then naturally cooled to room temperature and allowed to stand for 1 day (Example 6), and no heat treatment was performed. A sample (Comparative Example 6) was prepared.

(Evaluation)
When the samples of Example 5 and Comparative Example 5 were heated at 200 ° C. for 60 minutes, the retardation value of each sample before and after heating was measured, and the rate of change of the retardation value before and after heating was calculated. The following results were obtained.
Example 5 Variation of 1% retardation value Comparative Example 5 Variation of 6% retardation value

Further, the samples of Example 6 and Comparative Example 6 were heated at 100 ° C. for 60 minutes, and the change rate of the retardation value of each sample was calculated in the same manner as described above. The following results were obtained.
Example 6 Fluctuation of 1% retardation value Comparative Example 6 Fluctuation of 6% retardation value

It is process drawing which shows an example of the manufacturing method of the optical element of this invention.

Explanation of symbols

3 Base material 4 Liquid crystal layer 6 Optical function layer 8 Optical element

Claims (20)

  An optical element having a support material and an optical functional layer obtained by curing a polymerizable liquid crystal material on the support material with a predetermined liquid crystal regularity, wherein the optical element is heat-treated at a predetermined temperature. When the film thickness of the optical functional layer after the heat treatment is A, and the film thickness of the optical functional layer after the optical element is heated again at the heat treatment temperature for 60 minutes is B. , (AB) / A, wherein the optical function layer has a thickness reduction rate of 5% or less.   The optical element according to claim 1, wherein the polymerizable liquid crystal material has a photopolymerization initiator.   The optical element according to claim 1, wherein the support material is a base material having orientation ability.   A retardation layer laminate comprising: a support material; and a retardation layer obtained by curing a polymerizable liquid crystal material on the support material with nematic regularity, smectic regularity, or cholesteric regularity. The layer laminate is heat-treated at a predetermined temperature, the retardation value of the retardation layer after the heat treatment is Ra, and the retardation layer laminate is heated again at the heat treatment temperature for 60 minutes. When the retardation value of the retardation layer is Rb, the retardation reduction rate of the retardation layer defined by (Ra−Rb) / Ra is 5% or less. Laminated body.   The retardation layer laminate according to claim 4, wherein the polymerizable liquid crystal material having cholesteric regularity includes a photopolymerization initiator, a polymerizable liquid crystal monomer, and a polymerizable chiral agent.   The retardation layer laminate according to claim 4, wherein the polymerizable liquid crystal material has a photopolymerization initiator and a polymerizable liquid crystal monomer.   The retardation layer laminate according to any one of claims 4 to 6, wherein the support material is a substrate having orientation ability.   A circularly polarized light control optical element comprising: a support material; and a cholesteric layer in which a polymerizable liquid crystal material is cured with cholesteric regularity on the support material, wherein the circular polarization control optical element is heat-treated at a predetermined temperature. The central reflection wavelength of the cholesteric layer after the heat treatment is λa, and the central polarization wavelength of the cholesteric layer after the circular polarization control optical element is heated again at the heat treatment temperature for 60 minutes is λb. , Wherein the rate of change of the central wavelength defined by | λa−λb | / λa is 5% or less.   The circularly polarized light controlling optical element according to claim 8, wherein the polymerizable liquid crystal material has a photopolymerization initiator, a polymerizable liquid crystal monomer, and a polymerizable chiral agent.   The circularly polarized light controlling optical element according to claim 8 or 9, wherein the support material is a base material having orientation ability.   An optical element having a base material and an optical functional layer in which a polymerizable liquid crystal material is cured with a predetermined liquid crystal regularity on the base material is subjected to a heat treatment at a predetermined temperature to form an optical element. A heat treatment method for an optical element, characterized by imparting heat resistance.   For an optical element having a base material and an optical functional layer in which the polymerizable liquid crystal material is cured with a predetermined liquid crystal regularity on the base material, isotropicity before polymerization of the polymerizable liquid crystal material A heat treatment method for an optical element, characterized by imparting heat resistance to the optical element by performing a heat treatment at a temperature higher than the layer.   The method according to claim 11 or 12, wherein the heat treatment is performed for a time of 10 minutes to 60 minutes.   The method according to any one of claims 11 to 13, wherein the polymerizable liquid crystal material contains a photopolymerization initiator.   The method according to claim 14, wherein the content of the photopolymerization initiator is 1% by mass or more.   The temperature of the heat treatment is a temperature within a range from a temperature applied in a manufacturing process of an optical device in which the optical functional layer is subsequently used or a temperature from the temperature at which the optical device is used to a temperature higher by 10 ° C. than the temperature. The method of any one of Claims 11-15.   The optical functional layer is a retardation layer, the polymerizable liquid crystal material contains a polymerizable liquid crystal monomer, and the liquid crystal regularity is nematic regularity, smectic regularity, or cholesteric regularity. Item 17. The method according to any one of Items 11 to 16.   The optical functional layer is a cholesteric layer, the polymerizable liquid crystal material contains a polymerizable liquid crystal monomer and a polymerizable chiral agent, and the liquid crystal regularity is cholesteric regularity. The method of any one of these.   The method according to any one of claims 11 to 16, wherein the polymerizable liquid crystal material contains a polymerizable liquid crystal monomer, and the polymerizable liquid crystal monomer molecule has a polymerizable functional group at both ends.   The method according to claim 19, wherein the polymerizable liquid crystal material includes a polymerizable liquid crystal monomer and a polymerizable chiral agent, and the polymerizable chiral agent molecule has a polymerizable functional group at both ends.

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