JP2016016538A - Optical laminate, method for manufacturing optical laminate, and transfer material for manufacturing optical laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical laminate including two or more cholesteric liquid crystal layers, an adhesive, and a substrate, which has a low haze value and high interlayer adhesiveness, and to provide a method for manufacturing the optical laminate and a transfer material for manufacturing the optical laminate.SOLUTION: The optical laminate includes a substrate, an adhesive layer, and two or more liquid crystal layers, in this order. The liquid crystal layers are formed by curing a cholesteric liquid crystal phase to fix: one of the liquid crystal layers is in contact with the adhesive layer; and the liquid crystal layer in contact with the adhesive layer has a highest curing degree in the two or more liquid crystal layers. The adhesive layer contains an adhesive component. The optical laminate has a haze value of 3% or less. The method for manufacturing an optical laminate includes a step of transferring a transfer body including two or more liquid crystal layers formed through sequential coating steps, onto a substrate by using a temporal support body. The transfer material includes the transfer body on a temporal support body.SELECTED DRAWING: None

Description

  The present invention relates to an optical laminate, a method for producing the optical laminate, and a transfer material for producing the optical laminate.

  A layer in which a cholesteric liquid crystal phase is fixed (hereinafter referred to as a cholesteric liquid crystal layer) is known to exhibit selective reflection at a specific wavelength, and a film in which a plurality of cholesteric liquid crystal layers are laminated is a heat shielding film, an image display device, etc. Is used in various applications. For example, Patent Document 1 discloses an infrared light reflective article including a visible light transmissive substrate and an infrared light reflective cholesteric liquid crystal layer. Patent Document 2 discloses a polarizing element having a plurality of cholesteric liquid crystal layers.

  As an example of a method for producing a laminate including a plurality of cholesteric liquid crystal layers, there are the following methods described in Patent Documents 3 and 4, for example. First, a liquid crystal composition containing a polymerizable liquid crystal compound is applied onto a substrate, and after forming a cholesteric liquid crystal phase in the coating film, the coating film is cured by ultraviolet irradiation to fix the cholesteric liquid crystal phase and form a first layer. To do. Then, it is a method including applying the liquid crystal composition for forming the second layer on the surface of the first layer and repeating the above. Patent Document 3 discloses a technique related to repeatedly irradiating ultraviolet rays onto a previously formed layer. Patent Document 4 discloses an infrared reflective film in which a cholesteric liquid crystal layer is formed on the surface of an adhesion imparting layer to improve adhesion between liquid crystal layers.

Special table 2009-514022 gazette Japanese Patent No. 3500127 JP 2011-18037 A JP 2013-158970 A

A film in which a cholesteric liquid crystal layer is laminated is required to be used by firmly bonding to various base materials according to the spread of use. Patent Document 4 discloses a configuration in which the adhesion between the base material and the cholesteric liquid crystal layer is increased by using an adhesion-imparting layer. However, since it is produced by applying the liquid crystal composition before curing to the adhesion-imparting layer, a portion where the orientation of liquid crystal molecules is non-uniform is generated, and the resulting film has a high haze and its use is limited.
An object of the present invention is to make it possible to adhere a film in which a cholesteric liquid crystal layer is laminated to a substrate with high adhesiveness without affecting the optical properties of the cholesteric liquid crystal layer. More specifically, the object of the present invention is to provide an optical laminate having a low haze value and high interlayer adhesion as an optical laminate comprising two or more cholesteric liquid crystal layers, an adhesive, and a substrate. It is to be. Another object of the present invention is to provide a production method and a transfer material for producing the above optical laminate.

  In adhering a film in which a cholesteric liquid crystal layer is laminated to various substrates, it is considered preferable to use an adhesive containing a pressure-sensitive adhesive component having a high adhesive strength in order to increase adhesion. However, when the present inventors used a film containing a cholesteric liquid crystal layer adhered to a substrate using the above adhesive, an example in which the reflection spectrum of the cholesteric liquid crystal layer was changed was observed. The cause of this is thought to be that the adhesive component penetrates into the cholesteric liquid crystal layer at high temperatures and disturbs the alignment of the liquid crystal compound, and the present inventors have formed the liquid crystal composition containing the liquid crystal compound by curing. An attempt was made to suppress the intrusion of adhesive components by increasing the degree of cure of the cholesteric liquid crystal layer. However, if the degree of cure of the cholesteric liquid crystal layer is increased, the adhesion between the cholesteric liquid crystal layers and the bond between the cholesteric liquid crystal layer and the adhesive layer when the cholesteric liquid crystal layers are laminated are weakened. occured. Moreover, in order to improve the adhesiveness at the time of increasing the degree of curing, when the liquid crystal composition was cured by ultraviolet irradiation at a high oxygen concentration, a problem of blocking occurred.

Accordingly, the present inventors have further studied in consideration of the characteristics of the production method for producing a laminate having a plurality of cholesteric liquid crystal layers, and completed the present invention.
That is, the present invention provides the following [1] to [14].
[1] An optical laminate including a substrate, an adhesive layer, and two or more liquid crystal layers in this order,
The liquid crystal layer is a layer in which the cholesteric liquid crystal phase is fixed by curing the liquid crystal composition containing a polymerizable liquid crystal compound after making the cholesteric liquid crystal phase,
One of the liquid crystal layers is in contact with the adhesive layer;
The liquid crystal layer in contact with the adhesive layer has the highest degree of curing among the two or more liquid crystal layers,
The adhesive layer contains an adhesive component,
The optical laminated body whose haze value of the said optical laminated body is 3% or less.
[2] The optical laminate according to [1], wherein the degree of cure of the two or more liquid crystal layers is sequentially decreased from the substrate side.
[3] The optical laminate according to [1] or [2], wherein the adhesive component is urethane acrylate or epoxy acrylate.

[4] The optical layered body according to any one of [1] to [3], wherein the base material is polycarbonate.
[5] A method for producing an optical laminate including a substrate, an adhesive layer, and two or more liquid crystal layers in this order, and the following steps:
A liquid crystal composition containing a polymerizable liquid crystal compound is applied onto the first temporary support, and the liquid crystal composition is made into a cholesteric liquid crystal phase, and then cured to fix the first cholesteric liquid crystal phase and fix the first liquid crystal layer. Forming a first curing step;
A step of applying a liquid crystal composition containing a polymerizable liquid crystal compound on the previously formed liquid crystal layer and forming the liquid crystal layer in the same procedure as the formation of the first liquid crystal layer is repeated one or more times on the first temporary support. A repeated curing step of producing a transfer body comprising two or more liquid crystal layers;
A first transfer step in which the liquid crystal layer side surface finally formed in the repetitive curing step of the transfer body is adhered to a second temporary support with an adhesive, and then the first temporary support is peeled off;
The manufacturing method including the 2nd transcription | transfer process which adhere | attaches the said transcription | transfer body on a base material with the adhesive agent containing an adhesion component in the peeling surface obtained after the said peeling.
[6] The manufacturing method according to [5], including a step of peeling the second temporary support after the second transfer step.

[7] The production method according to [5] or [6], wherein all the curing is performed by ultraviolet irradiation.
[8] The liquid crystal composition containing a polymerizable liquid crystal compound is directly applied to the surface of the liquid crystal layer previously formed on the liquid crystal layer formed in advance. [5] to [7] The manufacturing method as described.
[9] The production method according to any one of [5] to [8], wherein at least one selected from the group consisting of a first temporary support and a second temporary support is a polyethylene terephthalate film.
[10] The production method according to any one of [5] to [9], wherein the adhesive component is urethane acrylate or epoxy acrylate.
[11] The production method according to any one of [5] to [10], wherein the substrate is polycarbonate.
[12] A transfer material for producing an optical laminate,
Including a temporary support, an adhesive layer, and a transfer body including two or more liquid crystal layers in this order,
The liquid crystal layer is a layer in which the cholesteric liquid crystal phase is fixed by curing after a liquid crystal composition containing a polymerizable liquid crystal compound is converted into a cholesteric liquid crystal phase,
The liquid crystal layer farthest from the temporary support has the highest degree of cure among the two or more liquid crystal layers,
A transfer material having a haze value of 3% or less.
[13] The transfer material according to [12], wherein the degree of cure of the two or more liquid crystal layers sequentially increases from the second temporary support side.
[14] The transfer material according to [12] or [13], wherein the temporary support is a polyethylene terephthalate film.

  According to the present invention, an optical laminate having good optical properties and high interlayer adhesion is provided as an optical laminate comprising two or more cholesteric liquid crystal layers, an adhesive, and a substrate. The present invention also provides a production method and a transfer material capable of providing the above optical laminate.

Hereinafter, the present invention will be described in detail. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.
In the present specification, for example, an angle such as “45 °”, “parallel”, “vertical”, or “orthogonal”, unless otherwise specified, has a difference from an exact angle within a range of less than 5 degrees. Means. The difference from the exact angle is preferably less than 4 degrees, and more preferably less than 3 degrees.
In this specification, “(meth) acrylate” is used to mean “one or both of acrylate and methacrylate”.

In this specification, “selective” for circularly polarized light means that the amount of light of either the right circularly polarized component or the left circularly polarized component of the irradiated light is greater than that of the other circularly polarized component. Specifically, when referred to as “selective”, the degree of circular polarization of light is preferably 0.3 or more, more preferably 0.6 or more, and even more preferably 0.8 or more. More preferably, it is substantially 1.0. Table In _{/ (I R + I L)} | Here, the degree of circular polarization, the intensity of the right circularly polarized light component of the light I _R, when the strength of the left-handed circularly polarized light component and I _L, | I _R -I _L Is the value to be In this specification, the degree of circular polarization is sometimes used to represent the ratio of circularly polarized light components.

  In this specification, “sense” for circularly polarized light means right circularly polarized light or left circularly polarized light. The sense of circularly polarized light is right-handed circularly polarized light when the electric field vector tip turns clockwise as time increases when viewed as the light travels toward you, and left when it turns counterclockwise. Defined as being circularly polarized.

  In this specification, the term “sense” may be used for the twist direction of the spiral of the cholesteric liquid crystal. The selective reflection by the cholesteric liquid crystal reflects right circularly polarized light when the twist direction (sense) of the cholesteric liquid crystal spiral is right, transmits left circularly polarized light, and reflects left circularly polarized light when the sense is left, Transmits circularly polarized light.

  Visible light is light having a wavelength visible to the human eye among electromagnetic waves, and indicates light having a wavelength range of 380 nm to 780 nm. Infrared rays (infrared light) are electromagnetic waves in the wavelength range that are longer than visible rays and shorter than radio waves. Among infrared rays, near infrared light is an electromagnetic wave having a wavelength range of 780 nm to 2500 nm. Ultraviolet rays are electromagnetic waves in a wavelength range shorter than visible light and longer than X-rays. The ultraviolet light may be light in a wavelength region that can be distinguished from visible light and X-rays, for example, light having a wavelength in the range of 10 nm to 380 nm.

<Optical laminate>
The optical laminate of the present invention is a laminate comprising a plurality of layers including two or more cholesteric liquid crystal layers.
The optical layered body includes a base material, an adhesive layer, and two or more cholesteric liquid crystal layers in this order, and is in direct contact with any one of the adhesive layer and the two or more cholesteric liquid crystal layers. The cholesteric liquid crystal layer in direct contact with the adhesive layer may be a cholesteric liquid crystal layer closest to the adhesive layer among the two or more cholesteric liquid crystal layers.
The optical layered body may include other layers such as an alignment layer and a surface protective layer. It is preferable that an adhesive layer is not included between two adjacent cholesteric liquid crystal layers of two or more cholesteric liquid crystal layers. It is preferable that another layer is not included between two adjacent cholesteric liquid crystal layers of two or more cholesteric liquid crystal layers, or only an alignment layer is provided. It is also preferable that two cholesteric liquid crystal layers adjacent to each other of two or more cholesteric liquid crystal layers are in direct contact with each other.

The shape of the optical layered body is not particularly limited, but may be usually a sheet shape, a film shape, a plate shape, or the like. Even if the optical layered body is long, it is cut into a necessary size according to the use mode (in this specification, “cutting” includes “punching” and “cutting”). There may be. In addition, the optical layered body can take various shapes other than the above in accordance with the shape of the substrate described later.
The optical layered body may be, for example, a light reflecting material or a circularly polarized light separating film. As described later, the reflection wavelength may be adjusted by adjusting the pitch of the cholesteric liquid crystal phase to be a heat-shielding film that totally reflects light in the infrared wavelength range, and circularly polarized light in the visible wavelength range. It may be in a form that can be used as a reflective polarizer, a projection screen or the like used in an optical liquid crystal display device that selectively reflects.

<Optical properties of optical laminate>
The optical layered body exhibits optical characteristics mainly derived from a layer in which a cholesteric liquid crystal phase is fixed, and has a low haze value.

(Optical properties of a layer with a fixed cholesteric liquid crystal phase)
The optical laminate includes a layer in which a cholesteric liquid crystal phase is fixed. It is known that the cholesteric liquid crystal phase has a circularly polarized light selective reflection property that selectively reflects either right circularly polarized light or left circularly polarized light. Many films formed of a composition containing a polymerizable liquid crystal compound have been known as films exhibiting circularly polarized light selective reflection. For the layer in which the cholesteric liquid crystal phase is fixed, refer to those prior arts. Can do.

  The layer in which the cholesteric liquid crystal phase is fixed is a layer in which the orientation of the liquid crystal compound in the cholesteric liquid crystal phase is maintained. In this specification, a layer in which a cholesteric liquid crystal phase is fixed may be referred to as a cholesteric liquid crystal layer or a liquid crystal layer. The cholesteric liquid crystal layer is a layer cured by light irradiation or the like after the polymerizable liquid crystal compound is brought into an alignment state of the cholesteric liquid crystal phase. The cholesteric liquid crystal layer may be a layer in which a layer having no fluidity is formed by curing thereof, and at the same time, the layer is changed to a state in which the alignment form is not changed by an external field or an external force. In the cholesteric liquid crystal layer, it is sufficient that the optical properties of the cholesteric liquid crystal phase are maintained in the layer, and the liquid crystalline compound in the layer may no longer exhibit liquid crystallinity. For example, the polymerizable liquid crystal compound may have a high molecular weight due to a curing reaction and may no longer have liquid crystallinity.

  The layer in which the cholesteric liquid crystal phase is fixed exhibits circularly polarized light selective reflection derived from the helical structure of the cholesteric liquid crystal. The central wavelength λ of the circularly polarized light selective reflection depends on the pitch P (= spiral period) of the helical structure in the cholesteric phase and follows the relationship between the average refractive index n of the cholesteric liquid crystal layer and λ = n × P. Therefore, by adjusting the pitch of this spiral structure, the wavelength exhibiting circularly polarized light selective reflection can be adjusted. That is, by adjusting the n value and the P value, for example, in order to selectively reflect either the right circularly polarized light or the left circularly polarized light in at least a part of the near-infrared light wavelength range, λ can be between 780 nm and 2500 nm, and in order to selectively reflect either right circularly polarized light or left circularly polarized light in at least a part of the visible light wavelength region, the central wavelength λ is In order to selectively reflect either the right-handed circularly polarized light or the left-handed circularly polarized light in at least a part of the ultraviolet light wavelength range, the central wavelength λ may be 380 nm to 780 nm. Can be in the wavelength range of 10 to 380 nm. Since the pitch of the cholesteric liquid crystal phase depends on the type of chiral agent used together with the polymerizable liquid crystal compound or the concentration of the chiral agent, the desired pitch can be obtained by adjusting these. Two or more liquid crystal layers in the optical layered body may have the same period P or different depending on the application.

The sense of reflected circularly polarized light in the cholesteric liquid crystal layer coincides with the sense of a spiral. Therefore, as the liquid crystal layer, a cholesteric liquid crystal layer whose spiral sense is either right or left may be used. The two or more liquid crystal layers in the optical layered body may have the same or different spiral senses depending on the application.
For the method of measuring spiral sense and pitch, use the methods described in “Introduction to Liquid Crystal Chemistry Experiments”, edited by the Japanese Liquid Crystal Society, Sigma Publishing 2007, page 46, and “Liquid Crystal Handbook”, Liquid Crystal Handbook Editing Committee, page 196. be able to.

  The half-value width Δλ (nm) of the selective reflection band (circular polarization reflection band) showing the circularly polarized selective reflection follows that ΔΔ depends on the birefringence Δn of the liquid crystal compound and the pitch P, and Δλ = Δn × P. . Therefore, the width of the selective reflection band can be controlled by adjusting Δn. Δn can be adjusted by adjusting the kind of the polymerizable liquid crystal compound and the mixing ratio thereof, or by controlling the temperature at the time of fixing the alignment.

In addition, the reflection center wavelength and half value width of a cholesteric liquid crystal layer can be calculated | required as follows.
When the transmission spectrum of the light reflection layer is measured using a spectrophotometer UV3150 (Shimadzu Corporation), a peak of decrease in transmittance is observed in the selective reflection region. Of the two wavelengths having a transmittance of 1/2 the maximum peak height, the wavelength value on the short wave side is λ1 (nm) and the wavelength value on the long wave side is λ2 (nm). The reflection center wavelength and the half width can be expressed by the following formula.
Reflection center wavelength = (λ1 + λ2) / 2
Half width = (λ2−λ1)

  The width of the circularly polarized reflection band (usually “width” is substantially the same as “half-value width Δλ” because the circularly polarized reflection spectrum profile of the cholesteric liquid crystal layer is square) is usually the same for one material. It is about 50 nm to 150 nm. In order to widen the selection wavelength range, two or more cholesteric liquid crystal layers having different center wavelengths of reflected light with different periods P may be stacked. Alternatively, in one cholesteric liquid crystal layer, the control wavelength region can be widened by gradually changing the period P in the film thickness direction.

(Haze value of optical laminate)
The haze value of the optical laminate is 3% or less. In this specification, the haze value is obtained by measuring with a haze meter NDH2000 (manufactured by Murakami Color Research Laboratory Co., Ltd.). Theoretically, the haze value is a value calculated from the following formula.
Haze (%) = Td / Tt × 100 (Td: diffuse transmittance of visible light Tt: total light transmittance of visible light)
Here, the total light transmittance is an omnidirectional transmittance obtained using a spectrophotometer and an integrating sphere unit. The diffuse transmittance is a value that can be calculated by subtracting the direct transmittance from the omnidirectional transmittance. The direct transmittance is a transmittance at 0 ° based on a value measured using an integrating sphere unit. Visible light means light having a wavelength of 380 to 780 nm.
It is also preferable that the haze value of a portion including two or more liquid crystal layers (sometimes referred to as “transfer body” in this specification) excluding the base material and the adhesive layer of the optical layered body is 3% or less. The haze value of the transfer body is more preferably 2.5% or less, and further preferably 2% or less.

<Curing degree of cholesteric liquid crystal layer in optical laminate>
In the optical layered body of the present invention, among the two or more cholesteric liquid crystal layers, the cholesteric liquid crystal layer in contact with the adhesive layer has the highest degree of curing. In the optical layered body of the present invention, it is preferable that the degree of curing of two or more liquid crystal layers is sequentially decreased from the adhesive layer side.
In the present specification, the degree of cure is a value represented by the following formula.
(Number of polymerizable functional groups in cholesteric liquid crystal layer obtained by curing) / (Number of polymerizable functional groups in liquid crystal composition before curing) × 100 (%)
That is, the degree of cure corresponds to the consumption rate of polymerizable functional groups (usually double bonds) when the liquid crystal composition is cured to produce a cholesteric liquid crystal layer. Therefore, the absorbance of the wave number of the peak value of absorption corresponding to the double bond in the IR absorption spectrum of each layer (absorption near 1620-1680 cm ⁻¹ ) is expressed as “the number of polymerizable functional groups in the cholesteric liquid crystal layer”. The degree of cure can be determined as

The degree of cure of two or more layers formed from liquid crystal compositions having substantially the same type and concentration of the polymerizable liquid crystal compound can be compared with the above-mentioned comparison of absorbance. That is, the higher the absorbance (the lower the consumption ratio of the polymerizable functional group), the lower the curing degree, and the lower the absorbance (the higher the consumption ratio of the polymerizable functional group), the higher the curing degree.
As will be described later, two or more cholesteric liquid crystal layers are composed of a cholesteric liquid crystal layer formed by light irradiation as a first layer, and a liquid crystal composition for forming a second cholesteric liquid crystal layer on the first layer. And a liquid crystal composition is cured by light irradiation. Usually, ultraviolet irradiation is used for light irradiation. In the above method, each time each layer is formed, the curing reaction is advanced by irradiating ultraviolet rays, so that the previously formed layer is repeatedly irradiated with ultraviolet rays. Therefore, the degree of cure is high in the previously formed layer, and when there is the first layer, the second layer, the third layer, and the nth layer from the lower layer side, the degree of cure is high in this order. Become.
In addition, the present inventors confirmed that the degree of curing was high in the layer repeatedly irradiated with ultraviolet rays by the following method.

The same liquid crystal composition as used in the examples was applied on a PET film, dried to form a cholesteric liquid crystal layer having a thickness of 10 μm, and the first UV irradiation at an illuminance of 28.3 mW / cm ² for 3 seconds. Carried out. The degree of cure was determined from the light absorbance of (1620-1680 cm ⁻¹ ) of the IR absorption spectrum of the layer after UV irradiation. The same layer was subjected to a second UV irradiation under the same conditions as the first UV irradiation, and the degree of cure was determined in the same manner as described above. Further, the third and fourth ultraviolet irradiations were performed under the same conditions as the first ultraviolet irradiation, respectively, and the degree of curing was measured. As a result, the degree of curing after the first ultraviolet irradiation was the smallest (80%), and the degree of curing increased with each increase in the number of ultraviolet irradiations (second time: 85.2%, third time: 89.4%, 4th: 92.9%).
As a result, in the laminate including two or more cholesteric liquid crystal layers, the cholesteric liquid crystal layer on the outermost surface has the highest degree of curing, and the curing degree of the two or more liquid crystal layers gradually decreases from the outermost layer side. It can be seen that the laminated body can be obtained by the method of sequentially applying and curing the liquid crystal composition as described above.

The degree of curing can be adjusted by adjusting the reaction rate of the curing reaction of the liquid crystal composition (for example, the polymerization reaction of a polymerizable liquid crystal compound) that proceeds by irradiation with ultraviolet rays as described later. The degree of cure is preferably 70% or more in the liquid crystal layer having the lowest degree of cure in the optical layered body from the viewpoint of maintaining the mechanical strength of the layer and suppressing unreacted substances from flowing out of the layer. 75% or more, more preferably 80% or more. Further, in the liquid crystal layer having the highest degree of curing in the optical laminate, it is preferably 80% or more, more preferably 85% or more, and still more preferably 90% or more.
Details of a method for producing an optical laminate including two or more cholesteric liquid crystal layers will be described later.

<Liquid Crystal Composition Containing Polymerizable Liquid Crystal Compound>
The cholesteric liquid crystal layer is formed from a liquid crystal composition containing a polymerizable liquid crystal compound. The liquid crystal composition may be applied to the surface of a temporary support, an alignment layer, or another cholesteric liquid crystal layer, which is a lower layer, and then a cholesteric liquid crystal phase may be formed through drying or heating. Thereafter, it is sufficient that the layer is cured by a polymerization reaction or the like to fix the cholesteric liquid crystal phase.
In addition to the polymerizable liquid crystal compound, the liquid crystal composition may contain a chiral agent, a polymerization initiator, an alignment controller, and other additives.

(Polymerizable liquid crystal compound)
The polymerizable liquid crystal compound may be a rod-like liquid crystal compound or a disk-like liquid crystal compound, but is preferably a rod-like liquid crystal compound.
Examples of the rod-like polymerizable liquid crystal compound forming the cholesteric liquid crystal layer include a rod-like nematic liquid crystal compound. Examples of rod-like nematic liquid crystal compounds include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines. , Phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used. Not only low-molecular liquid crystal compounds but also high-molecular liquid crystal compounds can be used.

Examples of the rod-like polymerizable liquid crystal compound are described in Makromol. Chem. 190, 2255 (1989), Advanced Materials 5, 107 (1993), US Pat. No. 4,683,327, US Pat. No. 5,622,648, US Pat. No. 5,770,107, International Publication WO95 / 22586. No. 95/24455, No. 97/00600, No. 98/23580, No. 98/52905, JP-A-1-272551, No. 6-16616, and No. 7-110469. 11-80081, JP-A-2001-328773, JP-A-2001-64627, JP-A-11-513019, JP-A-2007-279688, and the like.
As the discotic liquid crystal compound, for example, those described in JP-A 2007-108732 and JP-A 2010-244038 can be used.

The polymerizable liquid crystal compound can be obtained by introducing a polymerizable group into the liquid crystal compound. Examples of the polymerizable group include an unsaturated polymerizable group, an epoxy group, and an aziridinyl group, preferably an unsaturated polymerizable group, and particularly preferably an ethylenically unsaturated polymerizable group. The polymerizable group can be introduced into the molecule of the liquid crystal compound by various methods. The number of polymerizable groups possessed by the polymerizable liquid crystal compound is preferably 1 to 6, more preferably 1 to 3.
Two or more kinds of polymerizable liquid crystal compounds may be used in combination. When two or more kinds of polymerizable liquid crystal compounds are used in combination, the alignment temperature can be lowered.

  Moreover, it is preferable that the addition amount of the polymeric liquid crystal compound in a liquid-crystal composition is 80-99.9 mass% with respect to solid content mass (mass except a solvent) of a liquid-crystal composition, and 85-99. More preferably, it is 5 mass%, and it is especially preferable that it is 90-99 mass%.

(Chiral agent: optically active compound)
The chiral agent has a function of inducing a helical structure of a cholesteric liquid crystal phase. The chiral compound may be selected according to the purpose because the helical sense or helical pitch induced by the compound is different.
The chiral agent is not particularly limited, and known compounds (for example, liquid crystal device handbook, Chapter 3-4-3, TN, chiral agent for STN, page 199, Japan Society for the Promotion of Science, 142nd edition, 1989) Description), isosorbide, and isomannide derivatives can be used.
A chiral agent generally contains an asymmetric carbon atom, but an axially asymmetric compound or a planar asymmetric compound containing no asymmetric carbon atom can also be used as the chiral agent. Examples of the axial asymmetric compound or the planar asymmetric compound include binaphthyl, helicene, paracyclophane, and derivatives thereof. The chiral agent may have a polymerizable group. When both the chiral agent and the liquid crystal compound have a polymerizable group, they are derived from the repeating unit derived from the polymerizable liquid crystal compound and the chiral agent by a polymerization reaction between the polymerizable chiral agent and the polymerizable liquid crystal compound. A polymer having repeating units can be formed. In this aspect, the polymerizable group possessed by the polymerizable chiral agent is preferably the same group as the polymerizable group possessed by the polymerizable liquid crystal compound. Therefore, the polymerizable group of the chiral agent is also preferably an unsaturated polymerizable group, an epoxy group or an aziridinyl group, more preferably an unsaturated polymerizable group, and an ethylenically unsaturated polymerizable group. Particularly preferred.
The chiral agent may be a liquid crystal compound.

It is preferable that the chiral agent has a photoisomerizable group because a pattern having a desired reflection wavelength corresponding to the emission wavelength can be formed by irradiation with a photomask such as actinic rays after coating and orientation. As a photoisomerization group, the isomerization part of the compound which shows photochromic property, an azo, an azoxy, and a cinnamoyl group are preferable. Specific examples of the compound include JP 2002-80478, JP 2002-80851, JP 2002-179668, JP 2002-179669, JP 2002-179670, and JP 2002-2002. Use the compounds described in JP-A No. 179681, JP-A No. 2002-179682, JP-A No. 2002-338575, JP-A No. 2002-338668, JP-A No. 2003-313189, and JP-A No. 2003-313292. Can do.
The content of the chiral agent in the liquid crystal composition is preferably 0.01 mol% to 200 mol%, more preferably 1 mol% to 30 mol% of the amount of the polymerizable liquid crystal compound.

(Polymerization initiator)
The liquid crystal composition preferably contains a polymerization initiator. In the embodiment in which the polymerization reaction is advanced by ultraviolet irradiation, the polymerization initiator to be used is preferably a photopolymerization initiator that can start the polymerization reaction by ultraviolet irradiation. Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbon substituted aromatics. Group acyloin compounds (described in US Pat. No. 2,722,512), polynuclear quinone compounds (described in US Pat. Nos. 3,046,127 and 2,951,758), combinations of triarylimidazole dimers and p-aminophenyl ketone (US patents) No. 3549367), acridine and phenazine compounds (JP-A-60-105667, US Pat. No. 4,239,850), oxadiazole compounds (US Pat. No. 4,221,970), and the like. .
The content of the photopolymerization initiator in the liquid crystal composition is preferably 0.1 to 20% by mass, and preferably 0.5 to 5% by mass with respect to the content of the polymerizable liquid crystal compound. Further preferred.

(Crosslinking agent)
The liquid crystal composition may optionally contain a crosslinking agent in order to improve the film strength after curing and improve the durability. As the cross-linking agent, one that can be cured by ultraviolet rays, heat, moisture, or the like can be suitably used.
There is no restriction | limiting in particular as a crosslinking agent, According to the objective, it can select suitably, For example, polyfunctional acrylate compounds, such as a trimethylol propane tri (meth) acrylate and pentaerythritol tri (meth) acrylate; Glycidyl (meth) acrylate , Epoxy compounds such as ethylene glycol diglycidyl ether; aziridine compounds such as 2,2-bishydroxymethylbutanol-tris [3- (1-aziridinyl) propionate], 4,4-bis (ethyleneiminocarbonylamino) diphenylmethane; hexa Isocyanate compounds such as methylene diisocyanate and biuret type isocyanate; polyoxazoline compounds having an oxazoline group in the side chain; vinyltrimethoxysilane, N- (2-aminoethyl) 3-aminopropylto Alkoxysilane compounds such as methoxy silane. Moreover, a well-known catalyst can be used according to the reactivity of a crosslinking agent, and productivity can be improved in addition to membrane strength and durability improvement. These may be used individually by 1 type and may use 2 or more types together.
3 mass%-20 mass% are preferable, and, as for content of a crosslinking agent, 5 mass%-15 mass% are more preferable. When the content of the crosslinking agent is less than 3% by mass, the effect of improving the crosslinking density may not be obtained. When the content exceeds 20% by mass, the stability of the cholesteric liquid crystal layer may be decreased.

(Orientation control agent)
In the liquid crystal composition, an alignment control agent that contributes to stably or rapidly forming a cholesteric liquid crystal layer having a planar alignment may be added. Examples of the orientation control agent include fluorine (meth) acrylate polymers described in paragraphs [0018] to [0043] of JP-A-2007-272185, and paragraphs [0031] to [0034] of JP-A-2012-203237. Etc.] and the compounds represented by the formulas (I) to (IV).
In addition, as an orientation control agent, 1 type may be used independently and 2 or more types may be used together.

  The addition amount of the alignment control agent in the liquid crystal composition is preferably 0.01% by mass to 10% by mass, more preferably 0.01% by mass to 5% by mass with respect to the total mass of the polymerizable liquid crystal compound. 0.02% by mass to 1% by mass is particularly preferable.

(Other additives)
In addition, the liquid crystal composition may contain at least one selected from a surfactant for adjusting the surface tension of the coating film to make the film thickness uniform, and various additives such as a polymerizable monomer. . Further, in the liquid crystal composition, if necessary, a polymerization inhibitor, an antioxidant, an ultraviolet absorber, a light stabilizer, a colorant, metal oxide fine particles, and the like may be added as long as the optical performance is not deteriorated. Can be added.

(Solvent, etc.)
There is no restriction | limiting in particular as a solvent used for preparation of a liquid-crystal composition, Although it can select suitably according to the objective, An organic solvent is used preferably.
The organic solvent is not particularly limited and may be appropriately selected depending on the intended purpose. For example, ketones, alkyl halides, amides, sulfoxides, heterocyclic compounds, hydrocarbons, esters, ethers, etc. Is mentioned. These may be used individually by 1 type and may use 2 or more types together. Among these, ketones are particularly preferable in consideration of environmental load.

<Base material>
The optical layered body of the present invention includes a base material. In the optical layered body of the present invention, the type of substrate is not particularly limited because the substrate is different from a support necessary for producing a cholesteric liquid crystal layer and does not apply a liquid crystal composition in a liquid state thereon. However, the base material is preferably transparent, and when used in combination with a cholesteric liquid crystal layer and an adhesive layer, those capable of maintaining the haze value at the above values are preferable. As a base material, what is illustrated as a material which can be used as a below-mentioned temporary support body is mentioned. In particular, a polycarbonate film, a polyacrylic resin film, a cellulose triacetate film or a polyethylene terephthalate film (PET), a glass plate, and the like are preferable.
The film thickness of the substrate may be about 5 μm to 100 mm, preferably 10 μm to 50 mm, and more preferably 15 μm to 30 mm.
Moreover, it is preferable that the haze value of a base material is 0.5% or less.

<Adhesive layer (adhesive)>
Adhesives include hot melt type, thermosetting type, photocuring type, reactive curing type, and pressure-sensitive adhesive type that does not require curing, from the viewpoint of curing method, and the materials are acrylate, urethane, urethane acrylate, epoxy , Epoxy acrylate, polyolefin, modified olefin, polypropylene, ethylene vinyl alcohol, vinyl chloride, chloroprene rubber, cyanoacrylate, polyamide, polyimide, polystyrene, polyvinyl butyral, etc. can do. From the viewpoint of workability and productivity, the photocuring type is preferable as the curing method, and from the viewpoint of optical transparency and heat resistance, the material is preferably an acrylate, urethane acrylate, epoxy acrylate, or the like. .

In the optical layered body of the present invention, the adhesive layer between the base material and the cholesteric liquid crystal layer contains an adhesive component.
In the present specification, the adhesive component means a component that can achieve adhesion only by applying a slight pressure at room temperature for a short time without using water, a solvent, heat or the like. Specifically, an adhesive component satisfying the following criteria is used.
Adhesive component Melting point 130 ° C. or less Average molecular weight 100,000 or less Viscosity (25 ° C.) 100 to 10000 mPa · s (100 to 10000 cp)

  Specific examples of adhesives containing adhesive components include so-called organic adhesives, acrylate adhesives (including urethane acrylates or epoxy acrylates), silicone adhesives, rubber adhesives (natural rubber or synthetic) Examples of the adhesive containing a pressure-sensitive adhesive component include an adhesive containing urethane acrylate or epoxy acrylate.

<Method for producing optical laminate>
The optical layered body of the present invention includes two or more cholesteric liquid crystal layers having different degrees of curing. Of the two or more cholesteric liquid crystal layers, the configuration in which the outermost layer is the cholesteric liquid crystal layer having the highest degree of curing, and the configuration in which the degree of curing is sequentially decreased from the outermost layer to the outermost layer can be realized as described above. .
However, for example, as described in JP2013-158970A, when a cholesteric liquid crystal layer is formed by applying a liquid crystal composition containing a polymerizable liquid crystal compound on an adhesive layer, particularly on the surface of the adhesive layer, a cholesteric liquid crystal layer is formed. In the liquid crystal layer, the alignment of liquid crystal molecules is disturbed, and the haze value of the optical laminate is increased. Therefore, the optical laminate cannot be used in a form that requires a low haze value. Therefore, it is preferable to manufacture the optical laminate by a method including the following steps.

A liquid crystal composition containing a polymerizable liquid crystal compound is applied onto a first temporary support to form a cholesteric liquid crystal phase, and then cured to fix the cholesteric liquid crystal phase to form a first liquid crystal layer. Curing step;
A step of applying a liquid crystal composition containing a polymerizable liquid crystal compound on the previously formed liquid crystal layer and forming the liquid crystal layer in the same manner as the formation of the first liquid crystal layer is repeated one or more times on the first temporary support. A repeated curing step in which a transfer body comprising two or more liquid crystal layers is prepared;
The surface of the obtained transfer body on the side of the liquid crystal layer that was finally formed in the repeated curing step with respect to the first temporary support is attached to the second temporary support with an adhesive (preferably an adhesive not containing an adhesive component). A first transfer step of adhering to a support and subsequently peeling off the first temporary support;
A second transfer step, in which the release surface of the transfer body obtained after the first transfer step is adhered to a substrate with an adhesive containing an adhesive component.
After the second transfer step, the second temporary support may or may not be peeled off, and is preferably peeled off.

(Application method)
When applying a liquid crystal composition containing a polymerizable liquid crystal compound on the previously formed liquid crystal layer, it may be performed directly on the surface of the previously formed liquid crystal layer, or via another layer such as an alignment layer. Also good.
The method of applying the liquid crystal composition to the temporary support (first temporary support) of the liquid crystal composition, the previously formed liquid crystal layer, or the alignment layer surface is not particularly limited and may be appropriately selected depending on the purpose. For example, wire bar coating method, curtain coating method, extrusion coating method, direct gravure coating method, reverse gravure coating method, die coating method, spin coating method, dip coating method, spray coating method, slide coating method, etc. It is done. It can also be carried out by transferring a liquid crystal composition separately coated on a temporary support onto a substrate.

(Formation of cholesteric liquid crystal phase)
In the embodiment where the liquid crystal composition is prepared as a coating solution containing a solvent, the cholesteric liquid crystal phase may be formed by drying the coating film and removing the solvent. Moreover, in order to set it as the transition temperature to a cholesteric liquid crystal phase, you may heat the above-mentioned coating film if desired. For example, the cholesteric liquid crystal phase can be stably formed by heating to the temperature of the isotropic phase and then cooling to the cholesteric liquid crystal phase transition temperature. The liquid crystal phase transition temperature of the polymerizable liquid crystal composition described above is preferably in the range of 10 to 250 ° C., more preferably in the range of 10 to 150 ° C., from the standpoint of production suitability and the like. More preferably, it is within the range of ° C. By this alignment treatment, an optical thin film in which the polymerizable liquid crystal compound is twisted and aligned so as to have a helical axis in a direction substantially perpendicular to the film surface is obtained.

(Curing)
Curing is preferably performed by ultraviolet irradiation. The irradiation energy is preferably ^{20mJ / cm 2 ~50J / cm 2} , more preferably ^{100mJ / cm 2 ~1,500mJ / cm 2} , 100mJ / cm 2 ~800mJ / cm 2 is more preferred. The irradiation ultraviolet wavelength is preferably 350 nm to 430 nm.
In order to accelerate the curing reaction, ultraviolet irradiation may be performed under heating conditions. Moreover, it is preferable to maintain the temperature at the time of ultraviolet irradiation in the temperature range which exhibits a cholesteric liquid crystal phase so that a cholesteric liquid crystal phase may not be disturbed. In addition, since the oxygen concentration in the atmosphere is related to the degree of cure, if the desired degree of polymerization is not reached in the air and the film strength is insufficient, the oxygen concentration in the atmosphere is reduced by a method such as nitrogen substitution. It is preferable. The oxygen concentration is preferably 10% or less, more preferably 7% or less, and most preferably 3% or less. In order to improve the curing degree, a method of increasing the irradiation amount of ultraviolet rays to be irradiated and polymerization under a nitrogen atmosphere or heating conditions are effective. Moreover, after superposing | polymerizing once, the method of hold | maintaining at a temperature higher than superposition | polymerization temperature, and pushing a reaction further by thermal polymerization reaction, and the method of irradiating an ultraviolet-ray again can also be used.

(Film thickness of liquid crystal layer)
The thickness of each cholesteric liquid crystal layer is not particularly limited as long as it exhibits the above characteristics, but is preferably in the range of 1.0 to 150 μm, more preferably in the range of 4.0 to 100 μm. .
The total thickness of the cholesteric liquid crystal layer in the optical layered body of the present invention is preferably in the range of 2.0 to 300 μm, more preferably in the range of 8.0 to 200 μm. The selective reflection based on the spiral can be sufficiently ensured with a thickness of 2.0 μm or more. In addition, with a thickness of 300 μm or less, it is possible to sufficiently ensure the transmittance of light such as visible light.

(Temporary support)
The temporary support can function as a layer that supports a layer formed of a composition containing a liquid crystal compound, and can be peeled off from a layer (cholesteric liquid crystal layer) provided thereon. Being peelable means that the optical properties and the film surface state of the cholesteric liquid crystal layer can be separated without changing to an extent that affects use.
The temporary support is not particularly limited and may be rigid or flexible, but is preferably flexible in terms of easy handling. The rigid support is not particularly limited, but is a known glass plate such as a soda glass plate having a silicon oxide film on its surface, a low expansion glass, a non-alkali glass, a quartz glass plate, a metal such as an aluminum plate, an iron plate, or a SUS plate. A board, a resin board, a ceramic board, a stone board, etc. are mentioned.
Examples of the flexible support include polymer film, paper, aluminum foil, and cloth.

Examples of polymer films include cellulose acylate films (eg, cellulose triacetate film, cellulose diacetate film, cellulose acetate butyrate film, cellulose acetate propionate film), polyethylene, polypropylene, and polymers having an alicyclic structure (norbornene resin). (Arton: trade name, manufactured by JSR, amorphous polyolefin (Zeonex: trade name, manufactured by Nippon Zeon)), etc., polyester resin films such as polyethylene terephthalate and polyethylene naphthalate, polyethersulfone films , Polyacrylic resin film such as polymethylmethacrylate, polyurethane resin film, polycarbonate film, polystyrene and acrylo Examples thereof include styrene polymers such as tolyl / styrene copolymer (AS resin), among which cellulose acylate film, polyester resin film, polyolefin resin film, polycarbonate film, or styrene polymer are preferable. A rate film and a polyester resin film are more preferable, and a cellulose triacetate film or a polyethylene terephthalate film (PET) is more preferable.
In view of ease of handling, the thickness of the rigid support is preferably 100 to 3000 μm, and more preferably 300 to 1500 μm. As the film thickness of the flexible support,
What is necessary is just about 5 micrometers-1000 micrometers, Preferably it is 10 micrometers-250 micrometers, More preferably, they are 15 micrometers-90 micrometers.

In order to make the temporary support and the layer provided thereon peelable, the temporary support is subjected to surface treatment (eg, saponification treatment, glow discharge treatment, corona discharge treatment, ultraviolet (UV) treatment, flame treatment). It is preferable not to do so. That is, for example, a cellulose triacetate film preferably used as a support is preferably saponified but not saponified. As the temporary support, an unsaponified cellulose acylate film is preferred.
In order to make the temporary support and the layer provided thereon peelable, it is also preferable to select the layer provided thereon according to the selected temporary support material and adjust the composition.
In addition, to the long temporary support, inorganic particles having an average particle diameter of about 10 to 100 nm are provided in order to impart slip properties in the transport process or to prevent the back surface and the surface from sticking after winding. It is preferable to use what formed the polymer layer which mixed 5 to 40% by solid content mass ratio by the application | coating or co-casting with the temporary support body on the one side of a temporary support body.

(Orientation layer)
A liquid crystal composition containing a polymerizable liquid crystal compound may be applied to the alignment layer surface.
The alignment layer has a function of aligning liquid crystal molecules in the liquid crystal composition applied to the surface thereof.
The alignment film is a layer having an organic compound, a rubbing treatment of a polymer (resin such as polyimide, polyvinyl alcohol, polyester, polyarylate, polyamide imide, polyether imide, polyamide, modified polyamide), oblique deposition of an inorganic compound, or a micro groove. Or accumulation of organic compounds (eg, ω-tricosanoic acid, dioctadecylmethylammonium chloride, methyl stearylate) by the Langmuir-Blodgett method (LB film). Furthermore, an alignment film in which an alignment function is generated by application of an electric field, application of a magnetic field, or light irradiation is also known.
In particular, the alignment film made of a polymer is preferably subjected to a rubbing treatment and then a composition for forming a liquid crystal layer is applied to the rubbing treatment surface. The alignment film to be formed is particularly preferable. The rubbing treatment can be performed by rubbing the surface of the polymer layer several times in a certain direction with paper or cloth.
You may apply | coat a liquid-crystal composition to the surface which rubbed the temporary support body surface or the temporary support body without providing an alignment film. Further, a liquid crystal composition may be applied to the surface of the cholesteric liquid crystal layer. Furthermore, the alignment film may not be peeled off together with the temporary support to form a layer constituting the optical laminate of the present invention.
The thickness of the alignment layer is preferably 0.01 to 5 μm, and more preferably 0.05 to 2 μm.

<Transfer material>
A laminate having a transfer body including two or more liquid crystal layers on the second temporary support can be used as a transfer material for producing an optical laminate. That is, a laminate (transfer body) including two or more liquid crystal layers can be used as a transfer material for transferring to an arbitrary substrate. In the transfer material, the liquid crystal layer farthest from the temporary support has the highest degree of curing among the two or more liquid crystal layers. In addition, it is preferable that the degree of curing of two or more liquid crystal layers is sequentially increased from the second temporary support side.
Although it does not specifically limit as an adhesive agent for adhesion | attachment to the base material in the case of transcription | transfer, The adhesive agent containing an adhesive component with high adhesive force can be used.

The transfer material can be produced by a method including the following steps in this order.
A liquid crystal composition containing a polymerizable liquid crystal compound is applied onto a first temporary support to form a cholesteric liquid crystal phase, and then cured to fix the cholesteric liquid crystal phase to form a first liquid crystal layer. Curing step;
A liquid crystal composition containing a polymerizable liquid crystal compound is applied onto the previously formed liquid crystal layer, and the formation of the liquid crystal layer is repeated one or more times in the same manner as the first liquid crystal layer, and two liquid crystals are formed on the first temporary support. A repeated curing step of producing a transfer body comprising the above liquid crystal layer;
The surface of the liquid crystal layer side finally formed in the repeated curing step is applied to the first temporary support of the obtained transfer body by an adhesive (preferably an adhesive not containing an adhesive component). The process of making it adhere to.
The first temporary support may or may not be peeled off. If not peeled off, the first temporary support may be peeled off when adhered to the substrate.

  The features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Accordingly, the scope of the present invention should not be construed as being limited by the specific examples shown below.

[Example 1]
<Preparation of coating liquid for forming liquid crystal layer>
The following components were mixed to prepare a liquid crystal layer forming coating solution.
───────────────────────────────────
Liquid crystal layer forming coating solution ───────────────────────────────────
The following liquid crystal compound A (RM-257, manufactured by Merck) 95 parts by mass The following chiral agent B 4.5 parts by mass The following monofunctional monomer C 5 parts by mass MEK
(Methyl ethyl ketone, manufactured by Wako Pure Chemical Industries, Ltd.) 200 parts by mass cyclohexanone 20 parts by mass polymerization initiator D
(IRGACURE819 BASF) 4 parts by weight orientation control agent E 0.1 parts by weight ──────────────────────────────── ---

<Preparation of an adhesive containing no adhesive component>
Each component shown below was mixed to prepare an adhesive containing no adhesive component.
───────────────────────────────────
Adhesives that do not contain adhesive components ───────────────────────────────────
Vanaresin GH-1203 (manufactured by Shin-Nakamura Chemical Co., Ltd.) 50 parts by mass Biscoat 360 (manufactured by Osaka Organic Chemical Industry Co., Ltd.) 50 parts by mass polymerization initiator D 0.03 parts by mass MEK 300 parts by mass ───────── ──────────────────────────

<Formation of optical laminate>
On the surface of a 50 μm thick Fujifilm PET film (first PET), the above liquid crystal layer forming coating solution is dried using a wire bar so that the dry film thickness is about 4 to 5 μm. Application was at room temperature. The coating layer was dried at 30 ° C. for 30 seconds and then heated at 100 ° C. for 2 minutes to form a cholesteric liquid crystal phase. The cholesteric liquid crystal phase was irradiated with UV at an illuminance of 28.3 mW / cm ² for 3 seconds to fix the cholesteric liquid crystal phase to produce a liquid crystal first layer. The UV irradiation was performed at 30 ° C. with an Igraphic metal halide lamp to adjust the output and under nitrogen substitution at an oxygen concentration of 1% or less. Thereafter, the liquid crystal layer-forming coating solution was applied to the surface of the first layer, and a second layer was produced in the same procedure as the production of the first layer. Further, the liquid crystal layer-forming coating solution was applied to the surface of the second layer, and a third layer was produced in the same procedure as the production of the first layer. Said UV irradiation was implemented from the coating-film side seeing from the PET film, after apply | coating the coating liquid for 1st liquid crystal layer formation. Further, even after the second and third liquid crystal layer forming coating solutions were applied, UV irradiation was performed from the coating film side as seen from the PET film.

On the surface of the third layer of the laminate of the obtained liquid crystal layer, the adhesive prepared without the adhesive component prepared above was applied using a wire bar so that the dry film thickness after drying was about 2 to 3 μm. And heated in an atmosphere at 100 ° C. for 1 minute. Thereafter, the laminate was bonded to the surface of a 50 μm thick Fujifilm PET film (second PET film) on the adhesive surface. Next, the adhesive was irradiated with UV at an illuminance of 28.3 mW / cm ² for 3 seconds to cure the adhesive and form an adhesive layer. UV irradiation was performed at 30 ° C. while adjusting the output with an igraphic metal halide lamp and under nitrogen substitution. Thereafter, the first PET film was peeled off.

On the surface of the first liquid crystal layer obtained by peeling off the first PET, an epoxy acrylate adhesive (DIC Corporation Unidic V5500: resin component (bisphenol A type epoxy resin etc.) 80 parts by mass and n-acetate 20 parts by weight of butyl) was applied using a wire bar so that the thickness of the dried film after drying was about 2 to 3 μm and heated in a 100 ° C. atmosphere for 1 minute. Thereafter, UV irradiation was performed at an illuminance of 28.3 mW / cm ² for 3 seconds to cure the adhesive and prepare an adhesive layer. UV irradiation was performed at 30 ° C. while adjusting the output with an igraphic metal halide lamp and under nitrogen substitution. The obtained adhesive layer was adhered to a polycarbonate plate (made by Takiron Co., Ltd.) having a thickness of 2.0 mm. Thereafter, the second PET film was peeled off to obtain the optical laminate of Example 1.

<Evaluation of optical laminate>
The obtained optical layered body was allowed to stand in a 100 ° C. atmosphere for 100 hours, and then the following items were evaluated.
(Adhesion)
For the adhesion test, a cross-cut test as defined in JISK5600-5-6 was carried out, and peeling was 25 squares with 0 square being A, 1 square to 5 squares being B, and 6 squares being C.
(Shift of reflection band center wavelength)
The shift of the reflection band center wavelength was performed by measuring the transmittance spectrum with a spectrometer (manufactured by Shimadzu Corporation). The spectrum measurement was carried out by measuring the transmittance of the optical laminate in the range of 300 to 3000 nm. When the shift of the center of the reflection band from before to after placing in an atmosphere of 100 ° C. is less than 10 nm, A is set to B when the shift is more than 10 nm.
(Haze value)
The haze value was measured with a haze meter NDH2000 (manufactured by Murakami Color Research Laboratory Co., Ltd.).

[Example 2]
Urethane acrylate adhesive (made by DIC, Unidic 17-806: 80 parts by mass of resin component (urethane acrylate) and 20 parts by mass of solvent (butyl acetate, toluene)) The optical laminate of Example 2 was produced in the same procedure as in Example 1 except that was used.

[Comparative Example 1]
Apply the liquid crystal layer forming coating solution used in Example 1 on the surface of a 50 μm thick Fujifilm PET film at room temperature using a wire bar so that the dry film thickness after drying is about 4 to 5 μm. And applied. The coating solution was dried at 30 ° C. for 30 seconds and then heated at 100 ° C. for 2 minutes to obtain a cholesteric liquid crystal phase. The cholesteric liquid crystal phase was irradiated with UV at an illuminance of 28.3 mW / cm ² for 3 seconds to fix the cholesteric liquid crystal phase to produce a liquid crystal first layer. The UV irradiation was performed under nitrogen substitution by adjusting the output with an igraphic metal halide lamp at 30 ° C. Thereafter, the liquid crystal layer-forming coating solution was applied to the surface of the first layer, and a second layer was produced in the same procedure as the production of the first layer. Further, the liquid crystal layer-forming coating solution was applied to the surface of the second layer, and a third layer was produced in the same procedure as the production of the first layer. Said UV irradiation was implemented from the coating-film side seeing from the PET film, after apply | coating the coating liquid for 1st liquid crystal layer formation. Further, even after the second and third liquid crystal layer forming coating solutions were applied, UV irradiation was performed from the coating film side as seen from the PET film.

An epoxy acrylate-based adhesive (DIC Corporation Unidic V5500) was applied to the third layer surface of the obtained liquid crystal layer laminate using a wire bar so that the dry film thickness after drying was about 2 to 3 μm. And heated at 100 ° C. for 1 minute. Thereafter, the laminate was bonded to the surface of a polycarbonate plate (made by Takiron Co., Ltd.) having a thickness of 2.0 mm on the adhesive surface. Next, the adhesive was irradiated with UV at an illuminance of 28.3 mW / cm ² for 3 seconds to cure the adhesive and form an adhesive layer. The UV irradiation was performed under nitrogen substitution by adjusting the output with an igraphic metal halide lamp at 30 ° C. Thereafter, the PET film was peeled off to obtain an optical laminate of Comparative Example 1.

[Comparative Example 2]
The optical layered body of Comparative Example 2 was prepared in the same procedure as Comparative Example 1 except that a urethane acrylate adhesive (Unidic 17-806 manufactured by DIC) was used as the adhesive applied to the surface of the liquid crystal third layer. did.

[Comparative Example 3]
The optical layered body of Comparative Example 3 was produced in the same procedure as Example 1 except that the adhesive produced without the adhesive component produced above was used as the adhesive applied to the liquid crystal first layer.

[Comparative Example 4]
An epoxy acrylate adhesive (Unidic V5500 manufactured by DIC) was applied to the surface of a 50 μm thick Fujifilm PET film using a wire bar so that the dry film thickness after drying was about 2 to 3 μm. Heated for 1 minute in an atmosphere. Thereafter, the adhesive was irradiated with UV at an illuminance of 28.3 mW / cm ² for 3 seconds to cure the adhesive and prepare an adhesive layer. UV irradiation was performed at 30 ° C. while adjusting the output with an igraphic metal halide lamp and under nitrogen substitution. The liquid crystal layer forming coating solution used in Example 1 was applied to the surface of the obtained adhesive layer at room temperature using a wire bar so that the dry film thickness after drying was about 4 to 5 μm. . The coating film was dried at 30 ° C. for 30 seconds and then heated at 100 ° C. for 2 minutes to form a cholesteric liquid crystal phase. Thereafter, the cholesteric liquid crystal phase was irradiated with UV at an illuminance of 28.3 mW / cm ² for 3 seconds to fix the cholesteric liquid crystal phase to produce a liquid crystal first layer. UV irradiation was performed at 30 ° C. while adjusting the output with an igraphic metal halide lamp and under nitrogen substitution. Further, the liquid crystal layer-forming coating solution was applied to the surface of the first layer, and a second layer was produced in the same procedure as the production of the first layer. Further, the liquid crystal layer-forming coating solution was applied to the surface of the second layer, and a third layer was prepared in the same procedure as the preparation of the first layer, whereby an optical laminate of Comparative Example 4 was obtained. UV irradiation was performed from the side of the coating film as viewed from the PET film after the first liquid crystal layer forming coating solution was applied. Further, even after the second and third liquid crystal layer forming coating solutions were applied, UV irradiation was performed from the coating film side as seen from the PET film.

Claims (14)

An optical laminate including a base material, an adhesive layer, and two or more liquid crystal layers in this order,
The liquid crystal layer is a layer in which the cholesteric liquid crystal phase is fixed by curing the liquid crystal composition containing a polymerizable liquid crystal compound after making the cholesteric liquid crystal phase,
One of the liquid crystal layers is in contact with the adhesive layer;
The liquid crystal layer in contact with the adhesive layer has the highest degree of curing among the two or more liquid crystal layers,
The adhesive layer contains an adhesive component,
The optical laminated body whose haze value of the said optical laminated body is 3% or less. The optical laminate according to claim 1, wherein the degree of cure of two or more liquid crystal layers is sequentially decreased from the substrate side. The optical laminate according to claim 1, wherein the adhesive component is urethane acrylate or epoxy acrylate. The optical laminate according to any one of claims 1 to 3, wherein the substrate is polycarbonate. A method for producing an optical laminate including a base material, an adhesive layer, and two or more liquid crystal layers in this order, and the following steps:
A liquid crystal composition containing a polymerizable liquid crystal compound is applied onto a first temporary support, and the liquid crystal composition is made into a cholesteric liquid crystal phase, and then cured to fix the first cholesteric liquid crystal phase to form a first liquid crystal layer. Forming a first curing step;
A step of applying a liquid crystal composition containing a polymerizable liquid crystal compound on the previously formed liquid crystal layer and forming the liquid crystal layer in the same procedure as the formation of the first liquid crystal layer is repeated one or more times on the first temporary support. A repeated curing step of producing a transfer body comprising two or more liquid crystal layers;
A first transfer step in which the liquid crystal layer side surface finally formed in the repeated curing step of the transfer body is adhered to a second temporary support with an adhesive, and then the first temporary support is peeled off;
The manufacturing method including the 2nd transcription | transfer process which adheres the said transfer body to a base material with the adhesive agent containing an adhesion component in the peeling surface obtained after the said peeling. The manufacturing method of Claim 5 including the process of peeling a 2nd temporary support body after a 2nd transcription | transfer process. The manufacturing method according to claim 5 or 6, wherein all the curing is performed by ultraviolet irradiation. The manufacturing method as described in any one of Claims 5-7 with which the said application | coating on the liquid crystal layer formed previously of the liquid crystal composition containing a polymeric liquid crystal compound is directly performed on the surface of the liquid crystal layer formed previously. The manufacturing method according to any one of claims 5 to 8, wherein at least one selected from the group consisting of the first temporary support and the second temporary support is a polyethylene terephthalate film. The manufacturing method according to any one of claims 5 to 9, wherein the adhesive component is urethane acrylate or epoxy acrylate. The said base material is a polycarbonate, The manufacturing method as described in any one of Claims 5-10. A transfer material for producing an optical laminate,
Including a temporary support, an adhesive layer, and a transfer body including two or more liquid crystal layers in this order,
The liquid crystal layer is a layer in which the cholesteric liquid crystal phase is fixed by curing after a liquid crystal composition containing a polymerizable liquid crystal compound is converted into a cholesteric liquid crystal phase,
The liquid crystal layer farthest from the temporary support has the highest degree of cure among the two or more liquid crystal layers,
A transfer material having a haze value of 3% or less. The transfer material according to claim 12, wherein the degree of cure of the two or more liquid crystal layers sequentially increases from the second temporary support side. The transfer material according to claim 12 or 13, wherein the temporary support is a polyethylene terephthalate film.