WO2016104544A1 - Reflective-material production method - Google Patents

Abstract

According to the present invention, provided is a novel cost-effective production method for a reflective material including a circular polarization reflection layer comprising a layer in which a cholesteric liquid crystal phase is fixed, said circular polarization reflection layer being provided with a surface having a surface shape. The production method includes: a step in which a liquid crystal composition including a polymerizable liquid crystal compound is applied to a temporary support; a step in which the liquid crystal composition applied to the temporary support is dried; a step in which the layer of the dried liquid crystal composition is bonded to a complementary surface of a substrate or material, said complementary surface having a shape complementary to the abovementioned surface shape; and a step in which a stacked body including the substrate and the layer of the liquid crystal composition is heated or irradiated with light to cure the liquid crystal composition.

Description

Manufacturing method of reflector

The present invention relates to a method for manufacturing a reflector. The present invention particularly relates to a method for manufacturing a reflective material including a circularly polarized reflective layer having a surface shape.

For example, Patent Document 1 discloses a method for producing a reflective material including a circularly polarized reflective layer having a surface shape such as an uneven surface. In the method described in Patent Document 1, a polymerizable liquid crystal composition is applied to a base film to form a polymerizable liquid crystal layer, and the polymerizable liquid crystal layer is semi-cured and semi-cured to obtain a semi-cured polymerizable liquid crystal layer. Has been given a surface shape. And then, a method of fully curing the polymerizable liquid crystal layer to which the surface shape is imparted is specifically disclosed.

JP 2014-174321 A

An object of the present invention is to provide a novel manufacturing method of a reflecting material. In particular, it is an object of the present invention to provide a cost-effective manufacturing method as a manufacturing method of a reflective material including a circularly polarizing reflecting layer which is a circularly polarizing reflecting layer formed from a liquid crystal composition and has a surface shape. To do.

In the technique described in Patent Document 1, the liquid crystal composition is semi-cured before imparting the surface shape, but the fluidity of the liquid crystal composition is lowered by the semi-curing, so that the surface shape transferability is deteriorated. It is necessary to lengthen the pressing time during transfer. Therefore, make the surface shape transfer process a batch process with low production efficiency and lengthen the pressurization time, or increase the pressurization time by significantly lowering the transport speed in a continuous process separate from the application of the liquid crystal composition. This increases the manufacturing cost.
The inventors of the present invention have studied the conditions under which a shape can be imparted satisfactorily even if the pressurization time in the transfer process is shortened, and have completed the present invention.

That is, the present invention provides the following [1] to [11].
[1] A method for producing a reflective material including a circularly polarized reflective layer including a layer in which a cholesteric liquid crystal phase is fixed,
The circularly polarized light reflection layer has a surface having a surface shape,
The above manufacturing method includes the following:
Applying a liquid crystal composition containing a polymerizable liquid crystal compound on a temporary support;
Drying the liquid crystal composition coated on the temporary support,
The layer of the liquid crystal composition after the drying is bonded onto the complementary surface of a substrate or material having a complementary surface having a shape complementary to the surface shape, and the substrate and the liquid crystal composition The above-mentioned liquid crystal composition is cured by heating or irradiating the laminate with the layer.
[2] The surface having the surface shape is an uneven surface,
The concavo-convex surface alternately has inclined surfaces 1 and inclined surfaces 2 whose inclination directions are opposite to each other in the in-plane direction 1 of the circularly polarized light reflecting layer,
The maximum value of the angle formed by the inclined surface 1 and the flat surface inside the circularly polarized light reflecting layer and the maximum value of the angle formed by the inclined surface 2 and the flat surface inside the circularly polarized light reflecting layer are both 10 degrees or more. The production method according to [1], which is 60 degrees or less.
[3] The manufacturing method according to [2], wherein all the distances between the adjacent inclined surfaces 1 are 1 μm or more and 500 μm or less.

[4] The manufacturing method according to [3], wherein the distance is random.
[5] The manufacturing method according to [3], wherein the distance is constant.
[6] The layer of the liquid crystal composition after the drying is bonded to the surface of the complementary surface of the substrate or material having a complementary surface having a shape complementary to the surface shape of [1] to [5] The manufacturing method as described in any one.
[7] The production method according to any one of [1] to [6], wherein the bonding is performed at room temperature.
[8] The production method according to any one of [1] to [7], comprising peeling the temporary support from the circularly polarized light reflecting layer obtained after the curing.
[9] The production method according to any one of [1] to [8], wherein the substrate having a complementary surface is a microlens film, a prism film, or a lenticular sheet.
[10] The production method according to any one of [1] to [9], comprising peeling off the substrate from the circularly polarized light reflecting layer obtained after the curing.
[11] The production method according to [10], comprising bonding a surface generated by peeling the substrate and another substrate using an adhesive.
[12] The production method according to [10], comprising forming an overcoat layer on a surface generated by peeling the substrate.

According to the present invention, a novel method for producing a reflective material is provided. By the production method of the present invention, a reflective material comprising a circularly polarized light reflecting layer formed from a liquid crystal composition and having a desired surface shape can be produced cost-effectively.

It is a figure which shows typically the example of the cross section of the reflecting material which can be manufactured with the manufacturing method of this invention. It is a figure which shows typically the example of the shape of a circularly polarized light reflection layer. It is the picked-up image of the cross section of the reflecting material produced in the Example. It is a figure explaining the measuring method of the retroreflection signal strength performed in the Example. It is a figure which shows typically the example of arrangement | positioning in the display front of the optical member containing the reflecting material which can be manufactured with the manufacturing method of this invention.

Hereinafter, the present invention will be described in detail.
In the present specification, “˜” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value. In this specification, for example, an angle such as “45 degrees”, “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, an angle formed by a surface and a surface, a line and a surface, or a line and a line is expressed by an acute angle (an angle of 90 degrees or less).

In the present specification, each numerical value, numerical value range, and qualitative expression (for example, the expression “same”, “constant”, “entire”) includes numerical values that generally include an allowable error in this technical field. Are to be interpreted as indicating numerical ranges and properties. For example, when the wavelength is “same”, the difference is within 5 nm.
When the film thickness of the circularly polarized light reflection layer (distance from one point in the layer to the other surface) is constant, it means that the difference is less than 0.5 μm.

In this specification, the “surface” of a layer refers to the main surface (front surface, back surface) of the layer.
In the present specification, when the surface shapes are complementary to each other, it means a relationship that allows direct contact over the entire surfaces having the surface shapes. For example, the surface having a surface shape is an uneven surface. When the second layer is formed so as to fill the unevenness of the uneven surface of the first layer, a second layer having an uneven surface complementary to the uneven surface of the first layer is obtained. Further, the uneven surface of the first layer is complementary to the uneven surface of the obtained second layer.
In this specification, the values for the film thickness, the distance from one point in the layer to the other, the distance between the inclined surfaces 1 and the angle of the inclined surface are laser microscope, scanning electron microscope (SEM), transmission It is a value that can be measured in an image obtained with a microscope such as a scanning electron microscope (TEM).
In this specification, the “azimuth” means a direction in the plane of the reflecting material around the normal line of the reflecting material.
In this specification, “(meth) acrylate” is used to mean “one or both of acrylate and methacrylate”.

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” is sometimes 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 that can be seen by human eyes 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. Of the infrared light, near infrared light is an electromagnetic wave having a wavelength range of 780 nm to 2500 nm. Ultraviolet light is light having a wavelength in the range of 10 to 380 nm.

In the present specification, the “haze value” means a value measured using a haze meter NDH-2000 manufactured by Nippon Denshoku Industries Co., Ltd.
Theoretically, the haze value means a value represented by the following formula.
(Scattering transmittance of non-polarized light (natural light) of 380 to 780 nm) / (scattering transmittance of non-polarized light of 380 to 780 nm + transmissible parallel light of non-polarized light of 380 to 780 nm) × 100%
The scattering transmittance is a value that can be calculated by subtracting the parallel light transmittance from the obtained omnidirectional transmittance using a spectrophotometer and an integrating sphere unit. The parallel light transmittance is a transmittance at 0 degrees when based on a value measured using an integrating sphere unit.
In the present specification, the term “reflected light” or “transmitted light” is used to mean scattered light and diffracted light.

In addition, the polarization state of each wavelength of light can be measured using a spectral radiance meter or a spectrometer equipped with a circularly polarizing plate. In this case, the intensity of light measured through the right circularly polarizing plate corresponds to I _R , and the intensity of light measured through the left circularly polarizing plate corresponds to I _L. In addition, ordinary light sources such as incandescent light bulbs, mercury lamps, fluorescent lamps, and LEDs emit almost non-polarized light. However, the characteristic of producing polarized light of films mounted on these light sources is, for example, a polarization phase difference analyzer manufactured by AXOMETRIC It can be measured using AxoScan or the like.
Moreover, even if a circularly polarized light transmission plate is attached to an illuminance meter or an optical spectrum meter, it can be measured. The ratio can be measured by attaching a right circular polarized light transmission plate, measuring the right circular polarized light amount, attaching a left circular polarized light transmission plate, and measuring the left circular polarized light amount.

In this specification, “transparent” means having a light transmittance of 40% or more, preferably 50% or more, more preferably 60% or more, and further preferably 70% or more in the visible light wavelength region. It means being. The light transmittance is the light transmittance determined by the method described in JIS-K7105.

<Manufacturing method of reflective material>
The method for producing a reflective material of the present invention includes forming a circularly polarized light reflecting layer comprising a layer having a cholesteric liquid crystal phase fixed in the following procedure 1 or 2 and having a surface shape. .
Step 1
(1) A liquid crystal composition is applied on a temporary support.
(2) drying the liquid crystal composition applied on the temporary support;
(3) The liquid crystal composition layer obtained after (2) is bonded to a complementary surface of a substrate having a complementary surface having a shape complementary to the surface shape.
(4) The laminated body of the substrate and the liquid crystal composition layer is heated or irradiated with light to cure the liquid crystal composition.
(5) The temporary support is peeled off as necessary.

Step 2
(1) A liquid crystal composition is applied on a temporary support.
(2) drying the liquid crystal composition applied on the temporary support;
(3) The liquid crystal composition layer obtained after (2) is bonded to a complementary surface of a material having a complementary surface having a shape complementary to the surface shape.
(4) The laminated body of the material having a complementary surface and the liquid crystal composition layer is heated or irradiated with light to cure the liquid crystal composition.
(5) The temporary support is peeled off as necessary.
(6) peeling off the material having a complementary surface;
(7) If necessary, the surface from which the material having the complementary surface is peeled and another base material are bonded using an adhesive, or an overcoat layer is provided on the surface from which the material having the complementary surface is peeled off. .

Hereinafter, each material and each process used in the manufacturing method of the reflecting material will be described.

[Liquid crystal composition]
The cholesteric liquid crystal layer can be produced using a liquid crystal composition as a material. The liquid crystal composition includes a polymerizable liquid crystal compound. The liquid crystal composition preferably contains a chiral agent and a horizontal alignment agent. The liquid crystal composition may further contain a surfactant or a polymerization initiator.

(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.

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. Examples of polymerizable liquid crystal compounds are described in Makromol. Chem. , 190, 2255 (1989), Advanced Materials, Volume 5, 107 (1993), US Pat. Nos. 4,683,327, 5,622,648, and 5770107, International Publication WO95 / 22586. No. 95/24455, No. 97/00600, No. 98/23580, No. 98/52905, JP-A-1-272551, JP-A-6-16616, and JP-A-7-110469. 11-80081 and JP-A-2001-328773, and the like. 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.

The addition amount of the polymerizable liquid crystal compound in the liquid crystal composition is preferably 80 to 99.9% by mass with respect to the solid content mass (mass excluding the solvent) of the liquid crystal composition, and is preferably 85 to 99. It is more preferably 5% by mass, particularly preferably 90 to 99% by 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, 199 pages, 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.
The content of the chiral agent in the liquid crystal composition is preferably 0.01% by mass to 200% by mass and more preferably 1% by mass to 30% by mass with respect to the amount of the polymerizable liquid crystalline 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 photopolymerization initiators 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), a combination of triarylimidazole dimer and p-aminophenyl ketone (US patent) 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.
The content of the crosslinking agent is preferably 3% by mass to 20% by mass, and more preferably 5% by mass to 15% by mass. 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.

(Horizontal alignment agent)
In the liquid crystal composition, a horizontal alignment agent as 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 horizontal alignment 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. And compounds represented by the formulas (I) to (IV) as described above.
In addition, as a horizontal alignment agent, 1 type may be used independently and 2 or more types may be used together.

The addition amount of the horizontal alignment 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)
The liquid crystal composition may contain a solvent. 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.

(Layer with fixed cholesteric liquid crystal phase)
A layer in which a cholesteric liquid crystal phase is fixed can be formed from a liquid crystal composition containing a liquid crystal compound. 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.
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 circularly polarized light reflection layer may include one cholesteric liquid crystal layer or two or more layers, but is preferably a single layer.

The cholesteric liquid crystal layer may be a layer in which the orientation of the liquid crystal compound that is in the cholesteric liquid crystal phase is maintained. Typically, after the polymerizable liquid crystal compound is in the orientation state of the cholesteric liquid crystal phase, ultraviolet rays are used. Any layer may be used as long as it is polymerized and cured by irradiation, heating, or the like to form a layer having no fluidity, and at the same time, the orientation state is not changed by an external field or an external force. In the layer in which the cholesteric liquid crystal phase is fixed, it is sufficient that the optical properties of the cholesteric liquid crystal phase are retained 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 cholesteric liquid crystal layer 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, to show circularly polarized light selective reflection in the near-infrared light wavelength region, the center wavelength λ is 750 nm to 2000 nm, preferably 800 nm to 1500 nm. What should I do. 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. In the present specification, the center wavelength of selective reflection means the center wavelength when measured from the normal direction (helical axis direction) of the cholesteric liquid crystal layer.

In addition, the sense of the reflected circularly polarized light of the cholesteric liquid crystal layer coincides with the sense of the spiral. That is, a cholesteric liquid crystal layer with a spiral sense on the right reflects right circularly polarized light, and a cholesteric liquid crystal layer with a spiral sense on the left reflects left circularly polarized light. Therefore, a cholesteric liquid crystal layer with a spiral sense on the right may be used as the right circularly polarized reflective layer, and a cholesteric liquid crystal layer with a spiral sense on the left may be used as the left circularly polarized reflective layer. The method described in “Introduction to Liquid Crystal Chemistry Experiments” edited by the Japanese Liquid Crystal Society, Sigma Publishing 2007, p. 46, and “Liquid Crystal Manual”, Liquid Crystal Handbook Editorial Committee Maruzen, p. 196 can be used. .

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 reflective material is measured using a spectrophotometer UV3150 (Shimadzu Corporation), a decrease in transmittance peak 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 half-value width of the circularly polarized light reflection band is usually about 50 nm to 150 nm for one kind of material. 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.

[Temporary support]
The temporary support is used as a substrate on which the liquid crystal composition is applied. The temporary support may be peeled off after sticking described later or after curing. When the reflective material is used as a constituent member of the optical member, the temporary support may be peeled off after an information presentation layer described later is formed on the reflective material having the temporary support.

As the temporary support, a plastic film such as polyester such as polyethylene terephthalate (PET), polycarbonate, acrylic resin, epoxy resin, polyurethane, polyamide, polyolefin, cellulose derivative, silicone, or glass can be used.
The film thickness of the temporary support may be about 5 μm to 1000 μm, preferably 10 μm to 250 μm, more preferably 15 μm to 100 μm.

An alignment layer may be formed on the surface side of the temporary support to which the liquid crystal composition is applied. The alignment layer has a rubbing treatment of organic compounds such as polymers (resins such as polyimide, polyvinyl alcohol, polyester, polyarylate, polyamideimide, polyetherimide, polyamide, modified polyamide), oblique deposition of inorganic compounds, and microgrooves. It can be provided by means such as formation of a layer or accumulation of an organic compound (for example, ω-tricosanoic acid, dioctadecylmethylammonium chloride, methyl stearylate) by the Langmuir-Blodgett method (LB film). An alignment layer that generates an alignment function by application of an electric field, application of a magnetic field, or light irradiation may be used.

In particular, the alignment layer made of a polymer is preferably subjected to a rubbing treatment and a liquid crystal composition is applied to the rubbing treatment surface. The rubbing treatment can be performed by rubbing the surface of the polymer layer several times in a certain direction with paper or cloth.
The liquid crystal composition may be applied to the surface of the temporary support without providing the alignment layer, or the surface obtained by rubbing the temporary support.
When the temporary support is peeled off, the alignment film does not have to be peeled off together with the temporary support to form a layer constituting the reflector, and is peeled off at the interface between the temporary support and the alignment film so that the alignment film is reflected. It may be a layer constituting the material.
The thickness of the alignment layer is preferably 0.01 to 5 μm, more preferably 0.05 to 2 μm.

[Application of liquid crystal composition]
The application method of the liquid crystal composition is not particularly limited and can be appropriately selected depending on the purpose. For example, a wire bar coating method, a curtain coating method, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, a die Examples thereof include a coating method, a spin coating method, a dip coating method, a spray coating method, and a slide coating method.

[Dry, Oriented]
The applied liquid crystal composition may be dried by leaving it as it is or by heating. The heating temperature is preferably 200 ° C. or lower, and more preferably 130 ° C. or lower. In the course of drying the liquid crystal composition, the liquid crystal molecules can be aligned to form a cholesteric phase.

[Bonding]
Bonding is performed by applying the liquid crystal composition layer obtained after drying to a surface having a surface shape such as an uneven surface or a surface shape of a material (a complementary surface having a surface shape complementary to the surface shape of a circularly polarized light reflecting layer) ). At this time, for example, the liquid crystal composition may be in contact with the surface of the uneven surface so as to fill a recessed portion such as the uneven surface. Thereby, the entire surface of the uneven surface of the substrate or material having the uneven surface can be transferred to the surface of the liquid crystal composition layer. Alternatively, there may be a gap between the uneven surface and the liquid crystal composition. Thereby, a part of the uneven surface shape of the substrate or material having the uneven surface can be transferred to the surface of the liquid crystal composition layer.
Examples of the void include a void larger than 0 and not more than 50% of a volume (volume of liquid that can fill the depressed portion) formed by the depressed portion of the concave portion of the uneven surface of the base material. The location of the gap is not limited, but may be, for example, the bottom of the recessed portion.

Since the liquid crystal composition layer obtained after drying is not cured at the time of pasting and has fluidity, the surface shape can be efficiently and accurately transferred. Here, the state having fluidity means a state in which a trace of a fingerprint remains when light pressure is applied with a fingertip and the adhesiveness is exhibited.
The substrate or material having a surface shape, or the liquid crystal composition layer surface may be heated before contact so that the entire surface can be efficiently contacted. Heating is preferably performed at 40 ° C. to 110 ° C., more preferably 50 ° C. to 100 ° C. More preferably, the heating is performed on both the liquid crystal composition layer and the substrate or material having an uneven surface. You may pressurize in the case of pasting. The pressurization may be performed at, for example, 0.05 to 60 MPa, preferably 0.05 to 20 MPa.

The pressurization time is preferably from 0.01 seconds to 20 seconds, more preferably from 0.01 seconds to 10 seconds, and further preferably from 0.01 seconds to 5 seconds. If it is 0.01 seconds or longer, the surface shape can be sufficiently transferred, and if it is 20 seconds or less, good productivity can be secured.

Bonding may be performed under vacuum. The vacuum bonding can be performed by using a commercially available vacuum bonding machine such as a vacuum bonding machine V-SE6055aa manufactured by Climb Products.
Moreover, if the liquid crystal composition has fluidity at the time of bonding, a polymerization reaction may be performed before bonding. In the case of a photopolymerizable liquid crystal composition, irradiation with light having a wavelength of 350 to 430 nm in a range of 20 mJ / cm ² or less in an atmosphere having an oxygen concentration of 0.05% or more and 20% or less results in a liquid crystal composition. The polymerization reaction can proceed with fluidity, and fluidity can be controlled.

When forming a cholesteric liquid crystal layer that has no surface shape such as an uneven surface and is flat on both sides, the liquid crystal molecules are aligned in the drying step, and the polymerizable liquid crystal compound is perpendicular to the surface of the substrate or the like. A layer that is twisted and oriented so as to have a helical axis in the direction is obtained. The amount of retroreflected light in the circularly polarized light selective reflection band of the cholesteric liquid crystal layer becomes high when light enters from the normal direction (= helical axis direction) of the cholesteric liquid crystal layer, and light from a direction that makes an angle from the normal direction. There is almost no retroreflected light amount for the incident light. That is, high retroreflectivity is exhibited only in the normal direction of the layer. In the alignment step in the formation of the cholesteric liquid crystal layer, by forming the surface shape on the cholesteric liquid crystal layer by bonding the dry film of the liquid crystal composition to a complementary surface having a surface shape such as an uneven surface, the direction of the helical axis A partial structure (for example, a structure in which the normal direction of the inclined surface of the concavo-convex surface is the spiral axis direction) is formed at an angle with respect to the normal direction of the reflector, and the angle with respect to the normal direction is A reflective material having a high retroreflective property can be manufactured even with respect to the incidence of light from the forming direction.

[Curing]
The circularly polarized light reflecting layer is formed by curing the liquid crystal compound layer having a surface shape such as an uneven surface by bonding. Curing may be either heat curing by heating or photocuring by light irradiation, but photocuring is preferred. It is preferable to use ultraviolet rays for light irradiation. The irradiation energy is preferably ^{20mJ / cm 2 ~ 50J / cm} 2, 100mJ / cm 2 ~ 1,500mJ / cm 2 is more preferable. In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions or in a nitrogen atmosphere. The irradiation ultraviolet wavelength is preferably 350 nm to 430 nm. The polymerization reaction rate is preferably high from the viewpoint of stability, preferably 70% or more, and more preferably 80% or more.
The polymerization reaction rate of the polymerizable liquid crystal compound in the liquid crystal composition by curing can determine the consumption ratio of the polymerizable functional group using the IR absorption spectrum.
In addition, when the liquid crystal compound layer is peeled off from the uneven surface of the base material or material having an uneven surface, the liquid crystal compound layer may be cured before or after peeling, but before the peeling. Is preferred.

[Surface shape of circularly polarized reflective layer]
The reflecting material manufactured by the manufacturing method of the present invention includes a circularly polarized light reflecting layer having a surface having a surface shape. Although both surfaces of the circularly polarized light reflecting layer may be surfaces having a surface shape, it is preferable that one surface of the circularly polarized light reflecting layer is a surface having a surface shape and the other surface is a flat surface.
The flat surface is a plane having an average roughness (Ra value) of 1 μm square of less than 100 nm, preferably less than 50 nm. In this specification, the in-plane direction of the circularly polarized light reflecting layer is the in-plane direction of a flat surface or a surface obtained by flattening the surface irregularities of a surface having a surface shape.

The surface having the surface shape may be an uneven surface. The concavo-convex surface is preferably a surface having alternately inclined surfaces 1 and inclined surfaces 2 whose inclination directions are opposite to each other in one of the in-plane directions (in-plane direction 1) of the circularly polarized light reflecting layer. The in-plane direction 1 may be any direction as long as the following properties are satisfied. In this specification, the inclined surface 1 and the inclined surface 2 are used to indicate that the directions of inclination are opposite to each other. In the present specification, when the term “inclined surface” is simply used, the inclined surfaces 1 and 2 Both shall mean.

All the distances between the adjacent inclined surfaces 1 are preferably 1 μm or more and 500 μm or less. That is, it is preferable that at least one inclined surface 1 and at least one inclined surface 2 exist in the entire range divided by 500 μm in the in-plane direction 1. With such a configuration, the retroreflectivity without unevenness can be shown for light incident obliquely on the incident surface including the in-plane direction 1. The distance between the adjacent inclined surfaces 1 is the distance between the parts showing the maximum value of the angle formed with the flat surface (in the case of a curved surface) or the distance between the centers of the inclined surfaces (in the case of a straight line) (FIG. 1 (e ) Refer to “d” in FIG. The distance between adjacent inclined surfaces 1 may be constant in the in-plane direction 1 or may vary randomly.
In addition, the distance between the adjacent inclined surfaces 1 is the distance between the points which show the maximum value as an angle with the line | wire corresponding to a flat surface used in the microscope image of the cross-sectional view of the reflector in the in-plane direction 1 or the inclination. It shall be obtained by measuring the distance between the centers.

The maximum value of the angle formed between the inclined surface 1 and the flat surface inside the circularly polarized light reflecting layer is preferably 10 degrees or more and 60 degrees or less, and the maximum angle formed between the inclined surface 2 and the flat surface inside the circularly polarized light reflecting layer is preferable. The value is preferably 10 degrees or more and 60 degrees or less. The angles are more preferably 20 degrees or more and 50 degrees or less. By having an inclined surface of 10 degrees or more and 60 degrees or less, the circularly polarized light reflection layer can exhibit high retroreflectivity even when light is incident from a direction that makes an angle from the normal direction of the reflective material. As described above, the inclined surface appears in the in-plane direction 1 so that the directions of the inclination are alternately opposite. Therefore, the circularly polarized light reflection layer can exhibit high retroreflectivity even when light is incident from a direction that forms an angle with respect to the normal direction of the reflector in at least two directions that are in a linear direction. In addition, since the inclined surface is 60 degrees or less, a cholesteric structure having a helical axis direction perpendicular to the inclination is easily obtained.

The maximum value of the angle formed between the inclined surface 1 and the flat surface inside the circularly polarized light reflecting layer is the same as the maximum value of the angle formed between the inclined surface 2 and the flat surface inside the circularly polarized light reflecting layer. May be different. Further, the maximum value of the angle formed between the inclined surface 1 and the flat surface inside the circularly polarized light reflecting layer and the maximum value of the angle formed between the inclined surface 2 and the flat surface inside the circularly polarized light reflecting layer are respectively the in-plane directions. 1 may be constant or may vary randomly.
These angles are obtained by measuring the angle between the line corresponding to the flat surface and the inclination using the microscopic image of the cross-sectional view of the reflector in the in-plane direction 1. (See “θ” in FIG. 1E.)
The inclined surface may be a curved surface. In the case of a curved surface, the angle of the inclined surface is the angle of the tangent plane of the curved surface (the tangent of the curve in the sectional view).

It is preferable that the circularly polarized light reflection layer has a cross section sandwiched between straight lines and lines having alternating inclinations in at least one in-plane direction (in-plane direction 1). In this cross section, the distance between the adjacent slopes corresponding to the inclined surface 1 is 1 μm or more and 500 μm or less as described above (the distance between the points indicating the maximum angle formed with the straight line corresponding to the flat surface or the center of the inclination) Range). As described above, the maximum inclination angle between the circularly polarized light reflecting layer and the flat surface is 10 degrees or more and 60 degrees or less. An example of this cross section of the reflector is schematically shown in FIG. As an example of the line which has inclination alternately, the line (FIGS. 1 (a), (b), (f), (g), (h), (i))), a triangular wave (FIG. 1) (C)) A semicircle and a straight line (FIG. 1 (d)), a sine wave (FIG. 1 (e)), etc. are mentioned.

For example, the line having the slopes may include a straight line (for example, 10 μm or less, 5 μm or less, 3 m or less, 1 μm or less) without increasing or decreasing the distance at the maximum value or the minimum value (for example, (FIG. 1D Further, the distance between adjacent inclined surfaces 1 may be constant (other than (f), (h), and (i) in FIG. 1) in the in-plane direction 1 and may change randomly (FIG. 1 (f)). ), (H), (i)).
The difference between the maximum value and the minimum value of the distance corresponding to the flat surface from the line alternately having the above-described inclination (the depth of the unevenness) may be in the range of 2 μm or more and less than 200 μm, and 3 μm or more and less than 100 μm. It is preferable that it is the range of this, and it is more preferable that it is 20 micrometers or less. The increase / decrease width of the distance for each inclination in the in-plane direction 1 may be constant (other than (f), (h), (i) in FIG. 1) or may change randomly (FIG. 1 (f), ( h) and (i)). In addition, the said distance means the shortest distance from the point in an uneven surface to a flat surface.

The concavo-convex surface may be an concavo-convex surface having repeated concave portions having the same or substantially similar (including similar) cross-sectional shape. The repetition may be continuous, or may be intermittent as long as the distance between the adjacent inclined surfaces 1 is satisfied. It is also preferable that the repeated cross-sectional shape is a line-symmetric shape.

As an aspect of the uneven surface, a surface including the inclined surface 1 and the inclined surface 2 alternately in the in-plane direction 2 perpendicular to the in-plane direction 1 of the circularly polarized light reflecting layer can be mentioned. Examples of such surfaces include a shape in which the hemisphere is two-dimensionally continuous, a shape in which corner cubes and prisms are two-dimensionally continuous (FIGS. 2A and 2B), or any of these. Complementary uneven surface shape). The hemisphere may have a flat surface side as the center of the sphere, and may have the opposite side as the center of the sphere.
In this aspect, high retroreflectivity with respect to the incidence of light from a direction that makes an angle with respect to the normal line of the reflecting material as described above can be obtained in multiple directions.

As another aspect of the uneven surface, an uneven surface having a direction having no unevenness, that is, a straight line parallel to the in-plane direction 2 perpendicular to the in-plane direction 1 of the circularly polarized light reflection layer has a constant distance from the flat surface. And a concave / convex surface which is a set of points (FIG. 2 (c), (d), or a concave / convex surface shape complementary to one of these). Examples of the structure for providing such a surface include a lenticular shape (continuous shape of a semi-columnar body), a prism shape (a continuous shape of a triangular prism), a shape complementary to the lenticular shape, and the like.
In this embodiment, the reflective material is anisotropic in the retroreflective size. For example, the most retroreflective property can be obtained with respect to the incidence of light from a direction perpendicular to the ridgeline of the half-columnar body or the triangular column and at an angle with respect to the normal line of the half-columnar reflector as described above. it can. For example, when the angle between the straight line orthogonal to the ridge line and the component of the incident light or reflected light projected onto the reflecting material surface is φ in the reflecting material surface, when φ is 10 degrees or more, φ is 0 degree. In this case, it is 50% or less with respect to the retroreflectance with respect to the incidence of light from the direction forming the same angle.

The maximum thickness of the circularly polarized light reflecting layer is preferably 3 μm or more and 50 μm or less, more preferably 5 μm or more and 30 μm or less. The minimum value is preferably in the range of 10 μm or less, more preferably 3 μm or less, and the thickness may be not less than the selective reflection wavelength.

[Base material]
The substrate is preferably transparent in the visible light region and has a small refractive index difference from the circularly polarized reflective layer. This is because haze is less likely to occur due to the small difference in refractive index. The difference in refractive index is preferably 0.1 or less, more preferably 0.05 or less, and further preferably 0.02 or less.
Further, when the circularly polarized light reflection layer includes only one of a cholesteric liquid crystal layer having a spiral sense on the right and a cholesteric liquid crystal layer having a spiral sense on the left, the substrate may have low birefringence. preferable. In this specification, low birefringence means that the front phase difference is 10 nm or less at a wavelength of 550 nm. In this specification, the front phase difference is a value measured using an AxoScan manufactured by Axometrics.

The base material having a complementary surface having a shape complementary to the surface shape of the circularly polarized light reflecting layer includes a base material having an uneven surface complementary to the uneven surface of the circularly polarized light reflecting layer. Examples of the substrate having an uneven surface complementary to the uneven surface of the circularly polarized light reflecting layer include a microlens film, a prism film, and a lenticular sheet. As a microlens film, for example, ML1 or ML4 made by SKC Haas Display Films Co.Ltd., As a prism film, for example, HD74U made by Korea SKC Haas Display Films Co.Ltd., SPX2 made by Suntech Opto, As SPX3, SPX6, and lenticular sheet, for example, LS-200Y manufactured by FUJIFILM (China) Investment Co., Ltd. can be used.

These base materials may be used as they are, or may be used by adjusting the concave / convex shape to a desired shape by filling a part of the concave portion of the concave / convex surface. In such a case, the uneven shape may be adjusted to a desired shape by heating. As a method for filling a part of the concave portion of the concave and convex surface, for example, application of a resin such as an adhesive or vapor deposition of a metal material can be applied, but the method is not limited thereto.
When peeling the said base material from a liquid crystal composition after bonding, the uneven | corrugated surface of the said base material may release-process previously. As a release treatment method, for example, a method of laminating a fluorine-based polymer or a silicone resin on an uneven surface by coating or plasma treatment can be applied, but the method is not limited thereto.

The film thickness of the substrate may be about 5 μm to 1000 μm, preferably 10 μm to 250 μm, more preferably 15 μm to 100 μm, as the film thickness of the substrate having both flat surfaces. Also in the base material which has an uneven surface, the average value of a film thickness should just be the said range.

[Material with complementary surface]
In the present specification, among the substrates having complementary surfaces having a shape complementary to the surface shape of the circularly polarized light reflection layer, the substrate that may be peeled off may be referred to as “material”.
As a material having a complementary surface having a shape complementary to the surface shape of the circularly polarized light reflecting layer, any material (such as a mold) having the complementary surface can be used in addition to the substrate having the complementary surface. .

[Adhesion of another substrate or formation of an overcoat layer]
When the material having a complementary surface having a shape complementary to the surface shape is peeled after the liquid crystal composition is cured, another substrate may be bonded to the surface generated by peeling using an adhesive. An overcoat layer may be provided on the resulting surface.
The other base material and the overcoat layer are preferably transparent and have a small refractive index difference from the circularly polarized light reflection layer, and preferably have a low birefringence.

Another substrate used for another substrate may be flat on both sides. As another substrate, inorganic glass or a plastic film can be used. Examples of the plastic film include polyester such as polyethylene terephthalate (PET), polycarbonate, acrylic resin, epoxy resin, polyurethane, polyamide, polyolefin, cellulose derivative, and silicone.
As an adhesive used for adhesion between the surface generated by peeling and another substrate, an adhesive used for forming an adhesive layer described later can be used.

The overcoat layer can be provided by, for example, applying a layer made of a film containing a thermoplastic polymer or a composition containing an ultraviolet curable monomer to the surface of the circularly polarized light reflecting layer and then curing the composition. For example, when a composition containing an ultraviolet curable monomer is applied to the surface of the circularly polarized light reflecting layer that is a concavo-convex surface, it is preferably applied so that no voids are formed between the concavo-convex surface and the layer to be formed. This is to prevent a decrease in retroreflectance and an increase in haze.

Specific examples of the thermoplastic polymer include polyethylene, polypropylene, vinyl chloride resin, and polyurethane elastomer. When the overcoat layer is a film containing a thermoplastic polymer, even if it is applied directly to the entire surface of the concave and convex circularly polarized reflective layer, it is bonded to the concave and convex circularly polarized reflective layer as a cover film via an adhesive or adhesive. Also good. There are no particular restrictions on the pressure-sensitive adhesive or adhesive, but the pressure-sensitive adhesive is acrylic, silicone, urethane, and the adhesive is natural rubber, starch, acrylic, urethane, vinyl acetate, vinyl chloride. , Silicone, epoxy, isocyanate and the like. In the bonding step, bonding may be performed using heat or pressure according to the thickness of the thermoplastic polymer or the glass transition temperature. In the case of vinyl chloride resin, it is preferable to use heat and pressure of 100 ° C. or higher. In the case of polyethylene and polypropylene, it is preferable to use heat and pressure of 50 ° C. or higher. In the case of a polyurethane elastomer, heat is not necessary and it can be bonded only by pressure, which is preferable.

Examples of UV curable monomers include esters of polyhydric alcohols and (meth) acrylic acid (eg, ethylene glycol di (meth) acrylate, 1,4-dichlorohexane diacrylate, pentaerythritol tetra (meth) acrylate), penta Erythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, pentaerythritol hexa (meth) acrylate 1,2,3-cyclohexanetetramethacrylate, polyurethane polyacrylate, polyester polyacrylate), vinylbenzene and its derivatives (eg, 1,4-divinyl) , 4-vinylbenzoic acid-2-acryloyl ethyl ester, 1,4-divinylcyclohexanone), vinyl sulfone (eg, divinyl sulfone), acrylamide (eg, methylenebisacrylamide) and methacrylamide, epoxy monomer (diethylene glycol diglycidyl ether) Hexanediol diglycidyl ether, dimethylolpropane diglycidyl ether, polypropylene glycol diglycidyl ether, trimethylolpropane triglycidyl ether, and pentaerythritol tetraglycidyl ether). The ultraviolet curable monomer may be a mixture of two or more.

<Reflecting material>
The reflective material may be a film shape, a sheet shape, or a plate shape. An example of a cross section of the reflector is schematically shown in FIG.
The reflective material includes a circularly polarized reflective layer 1. The circularly polarized light reflecting layer 1 may usually be either a right circularly polarized light reflecting layer that selectively reflects right circularly polarized light or a left circularly polarized light reflecting layer that selectively reflects left circularly polarized light. The reflective material may include the base material 2, the adhesive layer 3, and the like in addition to the circularly polarized light reflective layer.

[Optical properties of reflective material]
The reflective material can reflect light in any wavelength region such as a visible light region, an ultraviolet light region, and an infrared light region. The reflecting material is preferably capable of reflecting light in the infrared wavelength region. For example, when the transmittance spectrum of the reflecting material is confirmed, it is preferable that a reflection wavelength band having a center wavelength in the range of 780 to 2000 nm, preferably in the range of 800 to 1500 nm can be confirmed. It is also preferable that the reflection wavelength is selected according to the use of the reflective material. For example, it is preferable that the wavelength is selected according to the wavelength of a light source such as an optical pen used in combination or the wavelength of infrared rays sensed by a sensor of an image sensor. The half width of the reflection wavelength band is 50 to 500 nm, preferably 100 to 300 nm.

The haze value of the reflective material is preferably 50% or less, and more preferably 30% or less.
The reflective material is preferably transparent in the visible light region.

The reflective material including the circularly polarized light reflecting layer having the convex surface in one of the in-plane directions (in-plane direction 1) of the circularly polarized light reflecting layer as described above is from a direction that forms an angle with respect to the normal line of the reflective material. At least one incident surface with high retroreflectivity is provided for light incidence. Retroreflection means reflection in which incident light is reflected in the incident direction. By having high retroreflectivity, high sensitivity can be obtained even when light is incident from a direction that makes an angle with respect to the normal line of the reflective material and the reflected light is detected from the same direction. For example, the above-described reflecting material has a wavelength at which the amount of retroreflected light is the largest when light having an angle of 45 degrees with respect to the normal of the reflecting material is incident on the incident surface from the specific surface side of the reflecting material. The amount of retroreflected light is 15% or more of the amount of retroreflected light of a standard diffusion plate (manufactured by Labsphere). The retroreflection can be obtained particularly when light is incident from the uneven surface side of the circularly polarized light reflection layer.

<An example of the use of the reflective material: optical member>
The reflective material can be used as a constituent member of the optical member.
The optical member further includes an information presentation layer. The optical member may be in the form of a film or a sheet.
In an optical member, the uneven surface of a circularly polarized light reflection layer should just be the information presentation layer side. As a layer structure of the optical member when the reflective material includes a base material, a structure in which an information presentation layer, a base material, and a circularly polarized light reflection layer are arranged in this order is preferable.

[Information presentation layer]
The information presentation layer has a pattern of a material that absorbs or reflects light having the reflection wavelength. That is, the information presentation layer has a pattern of a material that absorbs or reflects infrared rays. The pattern may be in the entire information presentation layer or in part. The material that absorbs or reflects the light having the reflection wavelength may be applied and printed on the surface of the reflective material by, for example, an ink jet method to form a pattern. Alternatively, for example, a pattern may be formed by uniformly applying to the surface of the substrate and then evaporating and printing in units of 0.5 to 3000 μm using an infrared laser. For the latter method, reference can be made to, for example, the description of JP-A-2011-152652.

The pattern may be a pattern that can give at least the position or coordinate information of the selected partial area in the information presentation layer when the partial area is selected. The part to be selected may be a unit that can be photographed by a pen-type imaging device having, for example, a light source that emits infrared rays and a sensor that senses infrared rays. Examples of the pattern include a dot pattern described in paragraphs 0123 to 0152 of JP 2014-98943 A.

(Material that absorbs or reflects infrared rays)
Examples of materials that absorb or reflect infrared rays include carbon inks, inks containing inorganic ions (metals such as copper, iron, and ytterbium), phthalocyanine dyes, dioctyl compound dyes, squalium dyes, croconium dyes, nickel complex dyes, and the like. Other known organic dyes, other known infrared absorbing dyes, known infrared reflective particles, and the like can be used. The material that absorbs or reflects infrared rays preferably has no reflection or absorption in the visible wavelength region.

(Adhesive layer)
The optical member may include an adhesive layer for bonding the layers. The reflective material may include an adhesive layer. The adhesive layer may be formed from an adhesive.
The adhesive layer preferably has a refractive index difference of 0.15 or less, more preferably 0.10 or less, and particularly preferably 0.05 or less. The adhesive layer is also preferably low birefringent.

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. .

[Use of optical members]
The use of the optical member is not particularly limited.
For example, it can be used as a handwriting input sheet used in a system using an optical pen that digitizes handwritten information and inputs it to an information processing apparatus. In use, the composition of the cholesteric liquid crystal layer is adjusted so that the wavelength of infrared rays emitted from the optical pen is the wavelength at which the reflective material shows reflection. Specifically, the spiral pitch of the cholesteric liquid crystal phase may be adjusted by the above method. When the optical member is used as a handwritten input sheet, it is sufficient that light is irradiated from the information presentation layer side of the optical member and reflected light is detected from the information presentation layer side of the optical member.

The optical member is disposed, for example, on the display surface or in front of the image display device, and can be used as a handwriting input sheet. In FIG. 5, the optical member 12 including the reflecting material 11 and the information presentation layer 5 disposed in front of the display 6 is shown. Light 21 irradiated with light from the information presentation layer 5 side having the dot pattern 13 and reflected by the reflector 11 can be detected.

The optical member may be bonded directly to the display surface or via another film or the like, and may be integrated with the display. For example, the optical member may be detachably attached to the display surface. When integrated, the optical member may be disposed between the forefront of the image display device or the protective front plate and the display panel. The optical member is preferably arranged so that the reflective material and the information presentation layer side are in this order from the display surface side. It is preferable that the display does not emit infrared light in the reflection wavelength region of the reflective material in the optical member so that there is no false detection with the image sensor of the optical pen.

Regarding a handwriting input system that digitizes handwritten information and inputs it to an information processing apparatus or an image display device equipped with a handwriting input sheet, Japanese Patent Application Laid-Open Nos. 2014-67398, 2014-98943, and 2008-165385 Reference can be made to [0021] to [0032] of Japanese Patent Laid-Open No. 2008-108236, Japanese Patent Laid-Open No. 2008-077451 or Japanese Patent No. 4725417.

The present invention will be described more specifically with reference to the following examples. The materials, reagents, amounts and ratios of substances, operations, and the like shown in the following examples can be appropriately changed without departing from the gist of the present invention. Therefore, the scope of the present invention is not limited to the following examples.

[Production of reflective material]
A surface of Toyobo Co., Ltd. Cosmo Shine A-4100 (PET: thickness 75 μm) not subjected to easy adhesion treatment was subjected to rubbing treatment, and coating solution 1 shown in Table 1 was applied to the rubbing treated surface of the dried film after drying. It apply | coated at room temperature so that thickness might be set to 10 micrometers.

The coating layer was dried at room temperature for 30 seconds and then heated at 85 ° C. for 1 minute. This coating layer was bonded to the concavo-convex surface of a lenticular sheet (manufactured by Fuji Glue (China) Investment Co., Ltd., LS-200Y) at room temperature using a laminator (manufactured by HARTEX, Bio330). Bonding was performed at 25 ° C., the bonding speed was 0.4 m / min, and the pressing time was 1 second.
The obtained laminated body was irradiated with 600 mJ / cm ² of ultraviolet light using a fusion D bulb (lamp 90 mW / cm) to form a circularly polarized light reflecting layer. Thereafter, the PET layer (Cosmo Shine A-4100) was peeled off to obtain a reflective material. FIG. 3 (1) shows an image obtained by photographing a cross section of the obtained reflecting material with a microscope (manufactured by Keyence Corporation, VHX-500F).

Example 2
In Example 1, reflection was performed in the same manner as in Example 1 except that the lenticular sheet (LS-200Y, manufactured by Fuji Gela (China) Investment Co., Ltd.) was heated at 85 ° C. for 1 minute and then the uneven surface was bonded to the coating layer. Made the material. FIG. 3 (2) shows an image obtained by photographing a cross section of the obtained reflecting material with a microscope (manufactured by Keyence Corporation, VHX-500F).
Example 3
A reflective material was prepared in the same manner as in Example 1 except that the uneven surface of the prism film (manufactured by Suntec Opto, SPX3) was bonded to the coating layer. FIG. 3 (3) shows an image obtained by photographing a cross section of the obtained reflecting material with a microscope (manufactured by Keyence Corporation, VHX-500F).

Example 4
The coating solution 2 shown in Table 2 was applied to the uneven surface of a microlens film (manufactured by SKC Haas Display Films Co. Ltd., Korea, ML1) with a No. 8 bar and then dried at 85 ° C for 1 minute to obtain a D valve made by Fusion. Curing was performed by irradiating with 300 mJ / cm ² of ultraviolet light (lamp 90 mW / cm). An image obtained by photographing a cross section of the obtained film with a microscope (manufactured by Keyence Corporation, VHX-500F) is shown in FIG.
A reflective material was prepared in the same manner as in Example 1 except that the uneven surface of the film was bonded to the coating layer. An image obtained by photographing a cross section of the obtained film with a microscope (manufactured by Keyence Corporation, VHX-500F) is shown in FIG.

Comparative Example 1
In Example 1, before the liquid crystal layer was bonded to the lenticular sheet, the liquid crystal layer was irradiated with ultraviolet rays of 300 mJ / cm ^{2 in} an atmosphere having an oxygen concentration of 0.03% or less using a fusion D bulb (lamp 90 mW / cm). Then, the lenticular sheet was pasted in the same manner as in Example 1 to produce a reflector, but no irregular shape was formed on the surface of the liquid crystal layer.
Comparative Example 2
A reflector was prepared in the same manner as in Example 1 except that the uneven surface of the microlens film (manufactured by SKC Haas Display Films Co. Ltd., ML8) was bonded to the liquid crystal. FIG. 3 (11) shows an image obtained by photographing a cross section of the obtained film with a microscope (manufactured by Keyence Corporation, VHX-500F).

(45 degree relative retroreflectivity)
Measurement was performed using an ultraviolet-visible near-infrared spectrophotometer V-670 (manufactured by JASCO Corporation) in combination with an absolute reflectance measurement unit ARV474S (manufactured by JASCO Corporation). As shown in FIG. 4, incident light is applied from a position inclined 45 degrees with respect to the normal direction of the sample 101 surface, and a signal at a position 8 degrees from the position (53 degrees with respect to the normal direction of the sample surface) is obtained. This was detected and used as the retroreflective signal intensity. In FIG. 4, a detector 103 is an InGaAs detector in the ultraviolet-visible near-infrared spectrophotometer V-670, and can detect near-infrared light. The incident light was adjusted to a wavelength of 850 nm, and the incident light was applied from the uneven surface side of the circularly polarized light reflecting layer during measurement.

The retroreflective signal intensity when a standard diffuser (manufactured by Labsphere) is installed at the sample position is 100%, and the ratio of the retroreflective intensity when each of the reflection films prepared above is installed at the sample position is a relative recursion. The reflectance was calculated by the following formula.

(Relative retroreflectivity) = (Retroreflective signal intensity of reflective film) / (Retroreflective signal intensity of standard diffuser) × 100

In Examples 1 to 3, the measurement was performed from two directions, a vertical direction and a parallel direction, with respect to the ridge line direction of the concavo-convex shape.

(Evaluation of uneven shape)
The surface asperity shape was evaluated by measuring the cross section of the reflector using a microscope (manufactured by Keyence Corporation, VHX-500F).

As can be seen from the results in Table 3, the reflective material obtained by the manufacturing method of the present invention has a high retroreflectivity in a direction that forms an angle of 45 degrees with respect to the normal direction of the reflective material, and the cholesteric liquid crystal Thus, it was possible to obtain a reflecting material in which a partial structure in which the spiral axis direction is an angle from the normal direction of the reflecting material.

DESCRIPTION OF SYMBOLS 1 Circularly polarized light reflection layer 2 Base material 3 Adhesive layer 4 UV curable resin 5 Information presentation layer 6 Display 11 Reflector 12 Optical member 13 Dot pattern 21 Light 101 Sample 102 Mirror 103 Detector

Claims (12)

A method of manufacturing a reflective material including a circularly polarized reflective layer including a layer in which a cholesteric liquid crystal phase is fixed,
The circularly polarized light reflection layer has a surface having a surface shape,
The manufacturing method includes the following:
Applying a liquid crystal composition containing a polymerizable liquid crystal compound on a temporary support;
Drying the liquid crystal composition coated on the temporary support,
The layer of the liquid crystal composition after the drying is bonded onto the complementary surface of a substrate or material having a complementary surface having a shape complementary to the surface shape, and the substrate and the liquid crystal composition The liquid crystal composition is cured by heating or irradiating the laminate with the layer. The surface having the surface shape is an uneven surface,
The concavo-convex surface has alternately inclined surfaces 1 and inclined surfaces 2 whose inclination directions are opposite to each other in the in-plane direction 1 of the circularly polarized light reflecting layer,
The maximum value of the angle formed between the inclined surface 1 and the flat surface inside the circularly polarized light reflecting layer and the maximum value of the angle formed between the inclined surface 2 and the flat surface inside the circularly polarized light reflecting layer are both 10 degrees. The manufacturing method according to claim 1, which is 60 degrees or more. The manufacturing method according to claim 2, wherein all the distances between the adjacent inclined surfaces 1 are 1 μm or more and 500 μm or less. The manufacturing method according to claim 3, wherein the distance is random. The manufacturing method according to claim 3, wherein the distance is constant. The layer of the liquid crystal composition after the drying is bonded to the surface of the complementary surface of a substrate or material having a complementary surface having a shape complementary to the surface shape. The manufacturing method as described. The production method according to any one of claims 1 to 6, wherein the bonding is performed at room temperature. The production method according to any one of claims 1 to 7, further comprising peeling the temporary support from the circularly polarized light reflecting layer obtained after the curing. The production method according to any one of claims 1 to 8, wherein the substrate having the complementary surface is a microlens film, a prism film, or a lenticular sheet. The production method according to any one of claims 1 to 9, further comprising peeling the substrate from the circularly polarized light reflecting layer obtained after the curing. The manufacturing method of Claim 10 including adhere | attaching the surface which peels the said base material, and another base material using an adhesive agent. The manufacturing method of Claim 10 including forming an overcoat layer in the surface produced by peeling the said base material.

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