JP2018112702A - Method of manufacturing reverse mode polymer dispersed light control device - Google Patents

Abstract

The present invention provides a method for producing a reverse mode polymer dispersed light control device having excellent permeability when no voltage is applied.
A method for producing a reverse mode polymer dispersed light control device according to the present invention comprises preparing a pair of substrates; a liquid crystal composition comprising a liquid crystal compound and a monomer component on one of the pair of substrates. Forming a coating layer by coating the other substrate on the coating layer; and irradiating the stack with active energy rays. In embodiments of the present invention, the temperature _{T IR} during active energy ray irradiation is -10 ° C. to 20 ° C..
[Selection] Figure 1

Description

  The present invention relates to a method for producing a reverse mode polymer dispersed light control device.

  Conventionally, a light control device using a light scattering effect in a composite of a polymer and a liquid crystal material has been developed. In such a composite, since the liquid crystal material has a structure in which the liquid crystal material is phase-separated or dispersed in the polymer matrix, the refractive index of the polymer and the liquid crystal material is matched, and a voltage is applied to the composite to apply the liquid crystal. By changing the orientation of the material, the transmission mode for transmitting light and the scattering mode for scattering light can be controlled.

  Examples of the driving method of the polymer dispersion type (for example, PDLC, PNLC) light control device include a normal mode and a reverse mode. The normal mode is the transmission mode when voltage is applied, the scattering mode when no voltage is applied; the reverse mode is the scattering mode when voltage is applied, and no voltage is applied. It becomes the transmission mode. Since the reverse mode is a transmission mode in a state where no voltage is applied, there is an advantage that power consumption is small and safety at the time of power failure is excellent. On the other hand, in the reverse mode, there is a demand for further improvement in transparency (transparency) when no voltage is applied.

Japanese Patent No. 5017963 JP 2014-080605 A JP 2014-080606 A

  The present invention has been made in order to solve the above-described conventional problems, and its main object is to provide a method for producing a reverse mode polymer dispersion type light control device having excellent permeability when no voltage is applied. There is.

The method for producing a reverse mode polymer dispersed light control device of the present invention comprises preparing a pair of substrates; applying a liquid crystal composition containing a liquid crystal compound and a monomer component onto one of the pair of substrates. Forming a coating layer; laminating the other substrate on the coating layer to produce a laminate; and irradiating the laminate with active energy rays. Temperature _{T IR} during active energy ray irradiation is -10 ° C. to 20 ° C..
In one embodiment, the monomer component includes a liquid crystal monomer.
In one embodiment, the difference between the liquid crystal phase transition temperature _TLC of the liquid crystal compound and the temperature _TIR is 50 ° C. or more.
In one embodiment, the active energy ray irradiation includes a first active energy ray irradiation for selectively irradiating a predetermined portion of the laminate, and after the first active energy ray irradiation, the laminate. And a second active energy ray irradiation for irradiating the entire surface, and a temperature _TIR2 at the time of the second active energy ray irradiation is −10 ° C. to 20 ° C.

  According to the present invention, the reverse mode polymer dispersion type having excellent permeability when no voltage is applied by setting the temperature at the time of irradiation with active energy rays for forming the light control layer to −10 ° C. to 20 ° C. A method of manufacturing a light control device can be realized.

It is the schematic explaining an example of the manufacturing method of the light modulation device of this invention.

  Hereinafter, although embodiment of this invention is described, this invention is not limited to these embodiment.

A. Outline of Method for Manufacturing Light Control Device A method for manufacturing a reverse mode polymer dispersion type light control device according to an embodiment of the present invention comprises preparing a pair of substrates; on one of the pair of substrates, Applying a liquid crystal composition containing a liquid crystal compound and a monomer component to form a coating layer; laminating the other substrate on the coating layer to produce a laminate; and irradiating the laminate with active energy rays Including: In embodiments of the present invention, the temperature _{T IR} during active energy ray irradiation is -10 ° C. to 20 ° C..

  Hereinafter, the manufacturing method of the above embodiment will be described more specifically with reference to FIG.

B. Substrate First, a pair of substrates 10a and 10b is prepared. In the substrates 10a and 10b, typically, a transparent electrode and an alignment film are provided in this order on a base material (not shown). The transparent electrode does not need to be provided on both of the pair of substrates, and may be provided only on one of the substrates depending on the purpose.

  The substrate may be a resin substrate or a glass substrate. A resin base material is preferable. As a material for forming the resin base material, polyester resins, (meth) acrylic resins, olefin resins, cyclic olefin resins, polycarbonate resins, polyurethane resins, cellulose resins, styrene resins, and the like can be preferably used. . Specific examples of polyester resins include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), isophthalic acid, cycloaliphatic dicarboxylic acid containing cyclohexane ring, alicyclic diol, etc. Copolymerized PET containing PET (PET-G), other polyesters, and copolymers and blends thereof. These materials may be used alone or in combination of two or more.

  The thickness of the substrate can be, for example, 20 μm to 500 μm, preferably 50 μm to 300 μm.

The transparent electrode can be formed using a metal oxide such as indium tin oxide (ITO), zinc oxide (ZnO), tin oxide (SnO ₂ ), for example. Alternatively, the transparent electrode can be formed of silver nanowires (AgNW), carbon nanotubes (CNT), an organic conductive film, a metal layer, or a laminate thereof. The transparent electrode can be patterned into a desired shape according to the purpose. For example, the blind function can be suitably imparted to the light control device by forming the transparent electrode in a pattern of vertical stripes, horizontal stripes, or lattices.

  The alignment film can be formed, for example, by subjecting a coating film such as polyimide or polyvinyl alcohol to a rubbing treatment with a cloth such as rayon.

  The light transmittance (wavelength 550 nm) of the substrate is preferably 80% or more, more preferably 85% or more, and further preferably 90% or more. If the light transmittance is within such a range, excellent transparency in the transmission mode can be realized.

C. Next, as shown in FIG. 1A, the liquid crystal composition is applied to the alignment film side surface of the substrate 10a to form a coating layer 40. The liquid crystal composition typically includes a liquid crystal compound and a monomer component.

  As the liquid crystal compound, any appropriate non-polymerization type liquid crystal compound is used. For example, nematic, smectic, and cholesteric liquid crystal compounds can be given. A nematic liquid crystal compound is preferably used because excellent transparency can be realized in the transmission mode. The dielectric anisotropy may be positive or negative.

  Specific examples of the liquid crystal compound include cyanobiphenyl, cyanophenylcyclohexane, cyanophenyl ester, benzoic acid phenyl ester, phenylpyrimidine compounds, and mixtures thereof as described in JP-A-11-174211, etc. And a low-molecular liquid crystal compound exhibiting a nematic phase or a smectic phase at room temperature or high temperature. Specific examples of such a low-molecular liquid crystal compound include biphenyl, phenylbenzoate, cyclohexylbenzene, azoxybenzene, azobenzene, azomethine, and terphenyl, as described in JP-A-11-153787. And various low molecular liquid crystal compounds such as biphenylbenzoate, cyclohexylbiphenyl, phenylpyrimidine, cyclohexylpyrimidine, and cholesterol. These low-molecular liquid crystal compounds may be used alone or in combination.

Liquid crystal phase transition temperature of the liquid crystal compound (a liquid crystal phase - isotropic phase transition _{temperature) T LC} is preferably 60 ° C. to 150 DEG ° C., more preferably 80 ° C. to 150 DEG ° C.. If the liquid crystal phase transition temperature is in such a range, the orientation of the liquid crystal compound becomes very high when the temperature at the time of irradiation of active energy rays described later is set to a predetermined low temperature. Therefore, in the obtained light control layer, the liquid crystal compound is phase-separated or dispersed in a state where the orientation is very high in the network structure formed by the polymer. As a result, the transparency (transparency when no voltage is applied) ) Having a very high reverse mode can be obtained.

  The monomer component can be appropriately selected according to the light transmittance, the refractive index of the liquid crystal compound, and the like. Typical examples of the monomer component include a polymerization type liquid crystal monomer (which may include a bifunctional or higher functional crosslinking monomer) and a monomer of an active energy ray curable resin. Specific examples of the active energy ray-curable resin include (meth) acrylic resins, silicone resins, epoxy resins, fluorine resins, polyester resins, and polyimide resins. A monomer component may be used independently and may use 2 or more types together. Preferably, the monomer component contains at least one liquid crystal monomer because the matching of the refractive index with the liquid crystal compound is facilitated.

  The temperature range in which the liquid crystal monomer exhibits liquid crystal properties varies depending on the type. Specifically, the temperature range is preferably 40 ° C to 120 ° C, more preferably 50 ° C to 100 ° C, and most preferably 60 ° C to 90 ° C.

  Any appropriate liquid crystal monomer can be adopted as the liquid crystal monomer. For example, polymerized mesogenic compounds described in JP-T-2002-533742 (WO00 / 37585), EP358208 (US52111877), EP66137 (US4388453), WO93 / 22397, EP02661712, DE195504224, DE44081171, and GB2280445 can be used. Specific examples of such a polymerization type mesogenic compound include, for example, trade name LC242 of BASF, trade name E7 of Merck, and trade name LC-Silicon-CC3767 of Wacker-Chem. As the liquid crystal monomer, for example, a nematic liquid crystal monomer is preferable.

  The compounding ratio (liquid crystal compound: monomer component (weight basis)) of the liquid crystal compound and the monomer component in the liquid crystal composition is, for example, 5:95 to 30:70, preferably 10:90 to 20:80. The liquid crystal composition is used as a photosensitive material by using a photosensitive monomer component, blending a photoinitiator, and the like.

  The liquid crystal composition may further include any appropriate component depending on the purpose. For example, the liquid crystal composition may further include a chiral agent. By using a chiral agent, the liquid crystal compound or the obtained liquid crystal polymer can be made cholesteric alignment. The type and amount of the chiral agent can be appropriately determined according to a desired set value such as a helical pitch. For example, the liquid crystal composition may further contain a polymerization initiator. The type and addition amount of the polymerization initiator can be appropriately determined according to the type and composition of the monomer component. Examples of other optional components include an antioxidant, a plasticizer, and a pigment. The content of optional components in the liquid crystal composition can be, for example, 10% by weight or less.

  Any appropriate method can be adopted as a method for applying the liquid crystal composition. Examples thereof include a roll coating method, a spin coating method, a wire bar coating method, a dip coating method, a die coating method, a curtain coating method, a spray coating method, a knife coating method (comma coating method and the like). The coating layer may be naturally dried or heat dried as necessary.

  Next, as shown in FIG. 1B, the substrate 10 b is laminated on the coating layer 40 so that the surface on the alignment film side faces the coating layer 40, thereby producing a laminate.

  You may heat-process a laminated body as needed. When performing the heat treatment, the heating temperature is, for example, 70 ° C. to 110 ° C., and the heating time is, for example, 40 seconds to 120 seconds. By performing the heat treatment, the disorder of the liquid crystal alignment caused by the application can be eliminated. As a result, the transparency when no voltage is applied can be further enhanced.

D. Formation of Light Control Layer by Active Energy Ray Irradiation Next, active energy ray irradiation is performed on the laminate as shown in FIG. Thereby, a monomer component superposes | polymerizes in the active energy ray irradiation area | region of the coating layer 40, and the light control layer 30 is formed. As the active energy ray, ionizing radiation such as ultraviolet ray, electron beam, α ray, β ray, γ ray and the like is used. Of these, ultraviolet rays are preferable. In the illustrated example, active energy ray irradiation is performed on the entire surface of the multilayer body, but active energy beam irradiation may be performed only on a predetermined position of the multilayer body.

When ultraviolet rays are employed as the active energy rays, the irradiation conditions of the ultraviolet rays can be appropriately set according to the type of monomer component. For example, the irradiation conditions of the ultraviolet rays in the active energy ray irradiation are preferably an illuminance of 1 mW / cm ^{2 to} 300 mW / cm ² , more preferably 10 mW / cm ^{2 to} 150 mW / cm ² and an irradiation time of preferably 1 minute to 30 minutes. More preferably, it can be 3 minutes to 15 minutes. As the light source, for example, a high-pressure mercury lamp, a low-pressure mercury lamp, a metal halide lamp, a UV-LED, or the like can be used.

In embodiments of the present invention, as described above, the temperature _{T IR} during ultraviolet irradiation was -10 ° C. to 20 ° C., preferably from -5 ° C. to 15 ° C.. When the temperature _TIR is within such a range, ultraviolet irradiation (polymerization of monomer components) is possible in a state where the alignment of the liquid crystal compound is very high. Therefore, in the obtained light control layer, the liquid crystal compound is phase-separated or dispersed in a state where the orientation is very high in the network structure formed by the polymer. As a result, the transparency (transparency when no voltage is applied) ) Having a very high reverse mode can be obtained.

The difference between the temperature _{T IR} and the liquid crystal phase transition temperature _{T LC} when the irradiation is preferably at 50 ° C. or higher, more preferably 60 ° C. to 95 ° C.. When the temperature difference is within such a range, it becomes easier to control the liquid crystal compound at the time of ultraviolet irradiation to a high alignment state.

  The monomer component is polymerized by the active energy ray irradiation as described above. As a result, the obtained light control layer contains a polymer (polymer of monomer components) and a liquid crystal compound. More specifically, the light control layer includes a liquid crystal compound that exists in a phase-separated or dispersed state in a network structure formed by the polymer.

  When the monomer component contains a liquid crystal monomer, a liquid crystal polymer is obtained by the above polymerization. The liquid crystal polymer is preferably aligned in a predetermined direction, and the alignment state is fixed. Since the alignment state of the liquid crystal polymer is fixed, switching between the transmission mode and the scattering mode can be suitably performed through a change in the alignment state of the liquid crystal compound. Such a liquid crystal polymer can be obtained by aligning liquid crystal monomers (which can include a bifunctional or higher functional cross-linked monomer) and then polymerizing or cross-linking the liquid crystal monomers. Here, a polymer is formed by polymerization, and a network structure is formed by crosslinking, but these are non-liquid crystalline. Therefore, in the obtained liquid crystal polymer, for example, a transition to a liquid crystal phase, a glass phase, or a crystal phase due to a temperature change specific to a liquid crystal compound does not occur.

  As described above, the light control layer 30 is formed, and a reverse mode polymer dispersed light control device is obtained.

E. Formation of light control layer and partition wall Irradiation with active energy rays (for example, ultraviolet rays) may be performed in two stages. Specifically, in the active energy ray irradiation, the entire surface of the laminate is irradiated after the first active energy ray irradiation for selectively irradiating a predetermined portion of the laminate and the first active energy ray irradiation. Second active energy ray irradiation. With such a configuration, a partition wall can be formed in the predetermined portion. The selective irradiation in the first active energy ray irradiation can be performed using a mask having a predetermined opening pattern. For example, by irradiating the laminated body through a mask having an opening pattern having a planar lattice shape, and then irradiating the entire surface of the laminated body by removing the mask, the light control layer and the continuous structure in the planar lattice shape are formed. And a partition wall that divides the light control layer into a plurality of sections. The light control layer and the partition can be formed as regions having different polymer contents from one liquid crystal composition due to a difference in exposure conditions. By setting it as such a structure, the light control device excellent in impact resistance and mechanical strength can be obtained.

In this embodiment, temperature _TIR2 at the time of 2nd active energy ray irradiation is -10 _degreeC- 20 _degreeC , Preferably it is -5 degreeC-15 degreeC. The temperature _TIR1 at the time of the first active energy ray irradiation can be set to any appropriate temperature. _TIR1 is, for example, 20 ° C to 50 ° C.

F. Light control device The light control device obtained by the manufacturing method of the present invention is in the reverse mode, and is in the scattering mode when a voltage is applied, and in the transmission mode when no voltage is applied. Specifically, due to the alignment action of the alignment film provided on the transparent electrode surfaces of the substrates 10a and 10b, the liquid crystal compound is aligned when no voltage is applied and becomes a transmission mode, and the alignment of the liquid crystal compound is disturbed by the application of voltage. It becomes a scattering mode. Note that the alignment film can be omitted as long as the liquid crystal compound can be aligned when no voltage is applied (for example, when the electrode surface is directly rubbed).

  The liquid crystal compound exhibits substantially the same refractive index as the polymer in the alignment state. Therefore, in the transmission mode (when no voltage is applied) in which the degree of alignment of the liquid crystal compound is high, light incident on the light control layer can be transmitted through the light control layer without greatly bending the traveling direction. At this time, the haze value of the light control layer may be, for example, 10% or less, preferably 7% or less. The haze value can be measured according to, for example, JIS K7136. In addition, since the polarization dependence by liquid crystal orientation may generate | occur | produce when chiral property is not provided, in such a case, it can measure through a polarizing plate.

  On the other hand, in the scattering mode (when voltage is applied) in which the degree of orientation of the liquid crystal compound is low, the orientation of the liquid crystal compound becomes irregular, so that the refractive index difference increases between the polymer and the liquid crystal compound. In this state, the light incident on the light control layer is scattered with the traveling direction greatly bent due to the difference in refractive index. At this time, the haze value of the light control layer may be, for example, 80% or more, preferably 85% or more.

  In the embodiment in which the partition walls are formed, as described above, the partition walls having a plan view shape corresponding to the opening pattern of the mask can be formed. For example, when a partition wall having a lattice shape in plan view is formed, the arrangement interval of the partition walls extending in the same direction is, for example, 1 mm or less, preferably 30 μm to 500 μm; The maximum width is, for example, 3 μm to 50 μm, preferably 5 μm to 30 μm.

  The partition wall has substantially no change in light transmittance when a voltage is applied and when no voltage is applied. The light transmittance (wavelength 550 nm) of the partition wall is, for example, 30% to 95%, preferably 40% to 90%.

  In one embodiment, the ratio (aperture ratio) of the area of the light control layer to the total area of the light control layer and the partition in plan view is, for example, 60% or more, preferably 70% or more, and more preferably. Is 80% to 95%. When the area (aperture ratio) of the light control layer is 60% or more, the light control function can be suitably exhibited.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples. Further, the following “parts” or “%” means “parts by weight” or “% by weight” unless otherwise specified.

[Example 1]
A polyimide (manufactured by JSR, “Optomer AL1254”) is applied to the electrode surface of a 40 mm × 30 mm PET film (thickness: 100 μm) having a transparent electrode (ITO film) of 100Ω / □ on one side, and the thickness is 90 ° C. After heating for 10 minutes, the film was baked at 120 ° C. for 90 minutes and rubbed in a uniaxial direction to form a parallel alignment film. As a result, a substrate A having a configuration of [alignment film / transparent electrode / PET film] was obtained.
Liquid crystal compound (HCCH Co., _{"854600-100", T} LC = 82 ° C.) and 95 parts of cross-linked liquid crystal monomer (BASF Corp., "LC242") obtained by mixing 5 parts. 0.95 parts of a polymerization initiator (manufactured by BASF, “IRGACURE TPO”) was added to the obtained mixture, heated to an isotropic phase, and stirred to obtain a liquid crystal composition.
The obtained liquid crystal composition was applied to the surface of the alignment film of the substrate A with a thickness of 10 μm. Next, another substrate A was bonded onto the coating layer so that the alignment film was in contact with the coating layer, and a laminate having a configuration of [substrate A / coating layer / substrate A] was produced. This laminate was subjected to a heat treatment at 90 ° C. for 60 seconds. Next, the laminate was irradiated with ultraviolet rays. Specifically, irradiation was performed continuously for 10 minutes at an illuminance of 30 mW / cm ² with an LED light source having a center wavelength of 365 nm. The temperature at the time of irradiation was 20 ° C. Thereby, the liquid crystal monomer was polymerized to form a liquid crystal polymer, and a composite (light control layer) in which the liquid crystal compound was phase-separated or dispersed in the network of the liquid crystal polymer was formed.
As described above, a reverse mode light control film was obtained.

  The haze when no voltage was applied to the obtained light control film was measured. The results are shown in Table 1.

[Example 2]
A reverse mode light control film was obtained in the same manner as in Example 1 except that the temperature during UV irradiation was 10 ° C. The haze when no voltage was applied to the obtained light control film was measured. The results are shown in Table 1.

[Example 3]
A reverse mode light control film was obtained in the same manner as in Example 1 except that the temperature during UV irradiation was 10 ° C. The haze when no voltage was applied to the obtained light control film was measured. The results are shown in Table 1.

[Example 4]
A reverse mode light control film was obtained in the same manner as in Example 1 except that the temperature during UV irradiation was 5 ° C. The haze when no voltage was applied to the obtained light control film was measured. The results are shown in Table 1.

[Example 5]
A reverse mode light control film was obtained in the same manner as in Example 1 except that the temperature during UV irradiation was 0 ° C. The haze when no voltage was applied to the obtained light control film was measured. The results are shown in Table 1.

[Example 6]
A reverse mode light control film was obtained in the same manner as in Example 1 except that the temperature at the time of ultraviolet irradiation was −5 ° C. The haze when no voltage was applied to the obtained light control film was measured. The results are shown in Table 1.

[Example 7]
A reverse mode light control film was obtained in the same manner as in Example 1 except that the temperature at the time of ultraviolet irradiation was −10 ° C. The haze when no voltage was applied to the obtained light control film was measured. The results are shown in Table 1.

[Comparative Example 1]
A reverse mode light control film was obtained in the same manner as in Example 1 except that the temperature at the time of ultraviolet irradiation was room temperature (23 ° C.). The haze when no voltage was applied to the obtained light control film was measured. The results are shown in Table 1.

[Comparative Example 2]
A reverse mode light control film was obtained in the same manner as in Example 1 except that the temperature during UV irradiation was 50 ° C. The haze when no voltage was applied to the obtained light control film was measured. The results are shown in Table 1.

[Comparative Example 3]
A reverse mode light control film was obtained in the same manner as in Example 1 except that the temperature during ultraviolet irradiation was 75 ° C. The haze when no voltage was applied to the obtained light control film was measured. The results are shown in Table 1.

[Comparative Example 4]
A reverse mode light control film was obtained in the same manner as in Example 1 except that the temperature at the time of ultraviolet irradiation was −15 ° C. The haze when no voltage was applied to the obtained light control film was measured. The results are shown in Table 1.

[Example 8]
To obtain a light control film of the reverse mode except for using "850100-100" _(T LC = 73 ℃) HCCH manufactured by the liquid crystal compound in the same manner as in Example 1. The haze when no voltage was applied to the obtained light control film was measured. The results are shown in Table 1.

[Example 9]
To give a light control film of the reverse mode except for using the "21600-000" _(T LC = 95 ℃) HCCH manufactured by the liquid crystal compound in the same manner as in Example 1. The haze when no voltage was applied to the obtained light control film was measured. The results are shown in Table 1.

[Example 10]
To obtain a light control film of the reverse mode except for using the "21700-000" _(T LC = 114 ℃) HCCH manufactured by the liquid crystal compound in the same manner as in Example 1. The haze when no voltage was applied to the obtained light control film was measured. The results are shown in Table 1.

  As is apparent from Table 1, reverse mode polymer dispersion type dimming with excellent transparency when no voltage is applied, by setting the temperature at the time of ultraviolet irradiation for forming the dimming layer to a low temperature within a predetermined range. You can get a device. If the temperature is too high or too low, the haze value will be high (bad). If the temperature is too high, the fluidity of the liquid crystal compound is too high and the orientation is insufficient; if the temperature is too low, the orientation is not fixed because the fluidity is too low and the photopolymerization reaction does not proceed; It is estimated that

  The light control device obtained by the manufacturing method of this invention is used suitably in field | areas, such as a film for window glasses, an image display apparatus.

10a substrate 10b substrate 30 light control layer 40 coating layer

Claims (4)

Preparing a pair of substrates,
Applying a liquid crystal composition containing a liquid crystal compound and a monomer component on one of the pair of substrates to form a coating layer;
Laminating the other substrate on the coating layer to produce a laminate, and irradiating the laminate with active energy rays,
Temperature _{T IR} during active energy ray irradiation is -10 ° C. to 20 ° C.,
A method for producing a reverse mode polymer dispersed light control device.   The manufacturing method according to claim 1, wherein the monomer component includes a liquid crystal monomer. The manufacturing method of Claim 1 or 2 whose difference of the liquid crystal phase transition temperature _TLC of the said liquid crystal compound and the said temperature _TIR is 50 degreeC or more. In the active energy ray irradiation, a first active energy ray irradiation that selectively irradiates a predetermined portion of the stacked body, and a first active energy ray irradiation that irradiates the entire surface of the stacked body after the first active energy ray irradiation. 2 active energy ray irradiation,
The temperature _TIR2 at the time of irradiation with the second active energy ray is −10 ° C. to 20 ° C.,
The manufacturing method in any one of Claim 1 to 3.