WO2019171877A1

WO2019171877A1 - Method for manufacturing layered body

Info

Publication number: WO2019171877A1
Application number: PCT/JP2019/004546
Authority: WO
Inventors: 洋平 ▲濱▼地; 小堂　厚司; 靖和桑山
Original assignee: 富士フイルム株式会社
Priority date: 2018-03-06
Filing date: 2019-02-08
Publication date: 2019-09-12
Also published as: JPWO2019171877A1; KR102445631B1; JP6741899B2; KR20200100799A

Abstract

Provided is a method for manufacturing a layered body provided with an optical film with improved orientation. In a first heating step (P1), a dry coating film (97) that includes a liquid crystal polymer (21) and a dichroic compound (31) is heated, bringing the dry coating film (97) to a first temperature (T1) that is higher than the melting point of the dichroic compound. In a first cooling step (P2), the dry coating film (97) is cooled, bringing the dry coating film (97) to a second temperature (T2) that is lower than the crystallization temperature (Tc) of the dichroic compound (31) and lower than the crystallization temperature (Ts) of the liquid crystal polymer (21). In a second heating step (P3), the dry coating film (97), having passed through the first cooling step (P2), is heated, bringing the dry coating film (97) to a third temperature (T3) that is lower than the nematic transition temperature (Tne) of the liquid crystal polymer (21).

Description

Manufacturing method of laminate

The present invention relates to a method for manufacturing a laminate.

In recent years, an attempt has been made to produce a polarizing plate that exhibits a polarizing function with a dichroic dye (Patent Document 1). A polarizing plate using a dichroic dye instead of polyvinyl alcohol (PVA) dyed with iodine for the purpose of improving heat resistance and moisture resistance is also known (Patent Document 2).

In Patent Document 1, a polarizing film, which is an optical film containing a dichroic dye, is formed on an alignment film. The polarizing film is formed from a coating solution in which a dichroic dye and a polymerizable liquid crystal compound (polymerizable liquid crystal compound) are dissolved in a solvent. Specifically, after the coating liquid is applied onto the alignment film and the formed coating film is polymerized at a temperature lower than the phase transition temperature of the polymerizable liquid crystal compound, the polymerizable liquid crystal compound is not polymerized. Dry with. Next, the dried coating film is heated above the nematic transition temperature of the polymerizable liquid crystal compound, and then cooled to a temperature at which a smectic phase liquid crystal state is obtained.

Patent Document 2 forms an alignment layer, which is an optical film containing a dichroic dye, on an alignment film. A liquid crystalline dichroic dye is used as the dichroic dye. A coating solution in which the liquid crystalline dichroic dye is dissolved in a solvent is applied onto the alignment film, and the solvent is removed from the formed coating film. Next, the orientation is fixed by heating the coating film to a temperature at which the liquid crystalline dichroic dye exhibits a liquid crystal state, and then the orientation is fixed by cooling.

JP 2013-228706 A JP 2005-189393 A

The manufacturing method of Patent Document 2 must use a liquid crystalline dichroic dye, but the manufacturing method of Patent Document 1 has an advantage in that it is not necessary to use a liquid crystalline dichroic dye. However, according to the manufacturing method of Patent Document 1, the orientation of the optical film may be insufficient.

Therefore, an object of the present invention is to provide a method for producing a laminate including an optical film with improved orientation.

The method for producing a laminate of the present invention includes a coating film forming step, a drying step, a first heating step, a cooling step, and a second heating step. The coating film forming step forms a coating film by applying a coating liquid containing a liquid crystalline compound, a dichroic compound, and a solvent that dissolves the liquid crystalline compound and the dichroic compound on the alignment film. . The drying process reduces the solvent from the coating. A 1st heating process heats the coating film in which the solvent decreased, and makes it 1st temperature higher than melting | fusing point of a dichroic compound. In the cooling step, the coating film that has undergone the first heating step is cooled to a second temperature that is lower than the crystallization temperature of the dichroic compound and lower than the crystallization temperature of the liquid crystalline compound. . A 2nd heating process heats the coating film which passed through the cooling process, and makes it the 3rd temperature lower than the nematic transition temperature of a liquid crystalline compound.

In the case where the dichroic compound has associative properties, the third temperature is preferably a temperature not lower than the association promotion temperature range that promotes the association of the dichroic compound.

The third temperature is preferably higher than at least the crystallization temperature of the liquid crystalline compound.

The third temperature is preferably lower than the crystallization temperature of the dichroic compound.

In the second heating step, the coating film that has undergone the cooling step is preferably heated at a heating rate of 0.1 ° C./second or more and 3.0 ° C./second or less.

In the second heating step, it is preferable to maintain the third temperature T3 for 1 second or longer.

According to the laminate production method of the present invention, a laminate comprising an optical film with improved orientation can be produced.

It is sectional drawing of a polarizing plate. It is explanatory drawing which shows the structure of a polarizing film. It is a block diagram of a manufacturing apparatus. It is explanatory drawing which shows the structure of a 1st protective layer formation part. It is explanatory drawing which shows the structure of an alignment film formation part. It is explanatory drawing which shows the structure of a coating optical film formation part. It is a block diagram which shows the structure of a temperature management part. It is a graph which shows the temperature control profile in a temperature management part. It is explanatory drawing which shows the state of the dry coating film in the temperature below nematic transition temperature. It is explanatory drawing which shows the state of the dry coating film made into 1st temperature. It is explanatory drawing which shows the state of the dry coating film after cooling. It is explanatory drawing which shows structures, such as a 1st heating part. It is explanatory drawing which shows the structure of a 2nd protective layer formation part.

[Laminate]
As shown in FIG. 1, the laminated body 10 manufactured by this invention is a polarizing plate which arranges incident light into specific polarized light, for example. The laminate 10 includes a base material 11, a first protective layer 12 laminated on the base material 11, an alignment film 13 laminated on the first protective layer 12, and a coating optical film 14 laminated on the alignment film 13. And a second protective layer 15 laminated on the coated optical film 14.

The substrate 11 is not particularly limited as long as it does not change when forming the coated optical film 14 or the like. For example, the substrate 11 may be a polyester polymer such as polyethylene terephthalate or polyethylene naphthalate, diacetyl cellulose, or Cellulose polymer such as triacetyl cellulose (TAC), polycarbonate polymer, acrylic polymer such as polymethyl methacrylate, styrene polymer such as polystyrene or acrylonitrile styrene copolymer, polyethylene, polypropylene, cyclic or norbornene structure Olefin polymers such as polyolefin and ethylene propylene copolymers, vinyl chloride polymers, amide polymers such as nylon or aromatic polyamide, imide polymers Sulfone polymers, polyethersulfone polymers, polyetheretherketone polymers, polyphenylene sulfide polymers, vinyl alcohol polymers, vinylidene chloride polymers, vinyl butyral polymers, acrylate polymers, polyoxymethylene polymers, epoxy polymers A transparent polymer such as the above, or a film or sheet made of a blend of these polymers can be used. Further, the substrate 11 may be glass. In this embodiment, the base material 11 is a TAC film.

The first protective layer 12 protects the alignment film 13 and the coating optical film 14 from water (including water vapor) and / or oxygen that permeates the base material 11. In this embodiment, the 1st protective layer 12 is polyvinyl alcohol (PVA), and shields the water etc. which permeate | transmit the TAC film which is the base material 11. FIG. In addition, when the base material 11 does not permeate | transmit water etc., the 1st protective layer 12 can be abbreviate | omitted from the laminated body 10. FIG.

The alignment film 13 regulates the alignment of the liquid crystalline compound contained in the coating optical film 14 under specific conditions. In the present embodiment, the alignment film 13 contains an azo compound, and this azo compound is a photo-alignment film that is isomerized by irradiation with ultraviolet rays or the like polarized in a specific direction and aligned along a specific direction. . As the azo compound, any of a monomer, an oligomer, and a polymer can be used. In this example, azobenzene that is a monomer is used. Instead of the azo compound, for example, cinnamate may be used. Instead of laminating the alignment film 13, the coated optical film 14 is contained by rubbing the surface of the substrate 11, the first protective layer 12, or other film provided on the first protective layer 12. The orientation of the liquid crystal compound to be controlled can be regulated.

The coated optical film 14 has a function as a polarizer in the laminate 10. The coating optical film 14 is an optical film formed by coating, and contains a liquid crystalline compound and at least one dichroic compound 31.

In the present embodiment, the liquid crystalline polymer 21 (see FIG. 2) is used as the liquid crystalline compound. The liquid crystalline polymer 21 is a polymer having a mesogenic group in the main chain or side chain. As the liquid crystalline polymer 21, for example, a thermotropic liquid crystalline polymer described in JP2011-237513A or a polymer having thermotropic liquid crystal described in JP2016-4055A can be used. Moreover, the liquid crystalline polymer 21 may have a crosslinkable group (for example, acryloyl group and methacryloyl group) at the terminal. In addition, as the liquid crystalline compound, other liquid crystalline compounds such as a liquid crystalline monomer or a liquid crystalline polymer different from the liquid crystalline polymer 21 can be used instead of or together with the liquid crystalline polymer 21.

In the present embodiment, as shown in FIG. 2, the liquid crystalline polymer 21 contained in the coating optical film 14 is a so-called side chain type, and includes a flexible main chain 22 and a side chain 24 having a mesogenic group 23. Have. The mesogenic group 23 is generally aligned along a predetermined direction (hereinafter referred to as X direction) by the alignment film 13 in the manufacturing process. The main chain 22 is generally oriented in a direction perpendicular to the X direction (hereinafter referred to as the Y direction). Accordingly, the liquid crystalline polymer 21 of the coating optical film 14 is arranged in a ladder shape or a network shape, and at least partially includes the one or more dichroic compounds 31 by the main chain 22 and the mesogenic group 23. Form.

The dichroic compound 31 is a compound having so-called dichroism, and there is a difference in the absorption intensity of each linearly polarized light when irradiated with two linearly polarized light having different polarization directions by 90 degrees. In the present embodiment, the dichroic compound 31 contained in the coating optical film 14 has the above-mentioned dichroism, and the property that two or more are bonded in a regular arrangement by intermolecular force under specific conditions ( So-called association). Therefore, when the liquid crystalline polymer 21 traps (captures) the dichroic compound 31 having two or more associative properties in the void 26, these dichroic compounds 31 associate to form an aggregate 32 in the manufacturing process. The orientation is roughly aligned. In addition, the orientation of the dichroic compound 31 and / or the aggregate 32 of the dichroic compound 31 trapped in the void 26 is generally regulated in the same direction as the mesogenic group 23.

Examples of the dichroic compound 31 include paragraphs [0067] to [0071] in JP 2013-228706 A, paragraphs [0008] to [0026] in JP 2013-227532 A, and JP 2013-209367 A. [0008] to [0015] paragraphs of the publication, paragraphs [0045] to [0058] of JP 2013-14883 A, paragraphs [0012] to [0029] of JP 2013-109090 A, JP 2013-101328 A Paragraphs [0009] to [0017], JP-A-2013-37353, paragraphs [0051] to [0065], JP-A-2012-63387, paragraphs [0049] to [0073], JP-A-11- [0016] to [0018] paragraphs of Japanese Patent No. 305036, and [0009] of Japanese Patent Laid-Open No. 2001-133630. [0011] paragraph, [0030] to [0169] of JP 2011-215337 A, [0021] to [0075] paragraph of JP 2010-106242 A, [0011] of JP 2010-215846 A. [0025] paragraph, [0017] to [0069] paragraph of JP 2011-048411 A, [0013] to [0133] paragraph of JP 2011-213610 A, [0074] of JP 2011-237513 A. ] To [0246] paragraphs, WO2016 / 060173 paragraphs [0005] to [0041], WO2016 / 136561 paragraphs [0008] to [0062], etc. can be used. Moreover, the compound which shows dichroism in the other wavelength range which is not visible light may be sufficient. For example, a compound showing dichroism in the infrared or ultraviolet wavelength region can be used.

The second protective layer 15 protects the coated optical film 14 from water or the like. The second protective layer 15 is formed of an acrylic polymer, an acrylate monomer polymer, an epoxy monomer polymer, or a cyclic olefin polymer (COP) or a cyclic olefin copolymer (COC). Not limited to.

In the laminate 10 configured as described above, the dichroic compound 31 and / or the aggregate 32 absorbs polarized light in the X direction with respect to light incident from the substrate 11 side or the second protective layer 15 side, Moreover, since it transmits polarized light in the Y direction, it functions as a polarizing plate. Further, the coating optical film 14 having a function as a polarizer can be formed very thin, and the orientation of the dichroic compound 31 is aligned with high accuracy in the coating optical film 14. For this reason, when the transmittance | permeability is made higher than the polarizing plate (henceforth an iodine addition PVA polarizing plate) which uses the PVA which added iodine for the laminated body 10 (especially, the transmittance | permeability is set to the high transmittance | permeability of 50% or more). In the case), the degree of polarization is higher than that of the iodine-added PVA polarizing plate. In addition, the coating optical film 14 can be formed thinner than the iodine-added PVA polarizing plate. As a result, the entire laminate 10 is thinner than the iodine-added PVA polarizing plate, and is equal to or higher than the iodine-added PVA polarizing plate. It has durability (heat resistance or moisture resistance).

[Laminate Manufacturing Apparatus and Manufacturing Method]
The laminate 10 is manufactured using, for example, a manufacturing apparatus 40 shown in FIG. In this example, the laminate 10 is manufactured in a long shape, but may be manufactured in a sheet shape by cutting the obtained long laminate 10. The manufacturing apparatus 40 includes a first protective layer forming unit 41, an alignment film forming unit 42, a coating optical film forming unit 43, and a second protective layer forming unit 44 in order from the upstream side in the transport direction of the long base material 11. Prepare. The first protective layer forming unit 41 forms the first protective layer 12 on the substrate 11. The alignment film forming unit 42 forms the alignment film 13 on the first protective layer 12. The coating optical film forming unit 43 forms the coating optical film 14 on the alignment film 13. The second protective layer forming unit 44 forms the second protective layer 15 on the coated optical film 14. The manufacturing apparatus 40 uses the transport mechanism (transport roller, transport roller drive mechanism, and the like) (not shown) to transport the base material 11 in the longitudinal direction, and the respective units sequentially stack the films or layers to form the laminate 10. obtain. In addition, the code | symbol Dc is attached | subjected to the conveyance direction of the base material 11. FIG.

As shown in FIG. 4, the first protective layer forming unit 41 includes a coating film forming unit 51 and a drying unit 52. The coating film forming unit 51 applies a coating solution 53 in which PVA is dissolved in a solvent on the base material 11 moving in the transport direction Dc to form a coating film 54. Thereafter, the drying section 52 forms the first protective layer 12 on the substrate 11 by reducing the solvent from the coating film 54 by heating, blowing, natural drying and / or other methods, and drying the coating film 54. To do.

As shown in FIG. 5, the alignment film forming unit 42 includes a coating film forming unit 61, a drying unit 62, and a light irradiation unit 63. The coating film forming unit 61 applies a coating solution 66 in which an azo compound is dissolved in a solvent on the first protective layer 12 to form a coating film 67. Thereafter, the drying unit 62 reduces the solvent from the coating film 67 by heating, blowing, natural drying, and / or other methods, and drying the coating film 67, thereby forming the dried coating film 68 on the first protective layer 12. Form. Next, the light irradiation unit 63 irradiates the dried coating film 68 with ultraviolet polarized light. As a result, the dried coating film 68 isomerizes the azo compound in accordance with the polarization direction of the ultraviolet rays to form the alignment film 13.

As shown in FIG. 6, the coating optical film forming unit 43 includes a coating film forming unit 91, a drying unit 92, and a temperature management unit 93. The coating film forming unit 91 applies a coating liquid 94 containing the liquid crystalline polymer 21, the dichroic compound 31, and a solvent for dissolving the liquid crystalline polymer 21 and the dichroic compound 31 on the alignment film 13. By doing so, the coating film 96 is formed (coating film formation process). In addition, the coating liquid 94 of this example is in a state where the liquid crystalline polymer 21 and the dichroic compound 31 are dissolved in a solvent. Thereafter, the drying unit 92 reduces the solvent from the coating film 96 by heating, blowing, natural drying, and / or other methods, and the coating film 96 is dried, thereby forming the dried coating film 97 on the alignment film 13. (Drying process). The temperature management unit 93 ripens the dried coating 97 by raising the temperature of the dried coating 97, which is a coating with a reduced solvent, and lowering the temperature, and / or maintaining a specific temperature range. By the temperature management performed by the temperature management unit 93, the orientation of the liquid crystalline polymer 21 and the dichroic compound 31 is more precisely adjusted in the dry coating film 97. As a result, the dried coating film 97 becomes the coated optical film 14 having a function as a polarizer. At the end of the drying process, the solvent may remain in the dry coating 97, and a small amount remains in this example.

As shown in FIG. 7, the temperature management unit 93 includes a first heating unit 101, a first cooling unit 102, a second heating unit 103, and a second cooling unit 104, and the temperature control shown in FIG. Manage the temperature according to the profile.

1st heating part 101 heats intermediate layered product 110 conveyed from drying part 92, and makes it specific temperature from the temperature at the time of conveying from drying part 92 (for example, normal temperature To). Specifically, the first heating unit 101 performs at least a first heating step P1 that heats at least the dry coating film 97 to a first temperature T1 that is higher than the melting point Tm of the dichroic compound 31. The melting point Tm of the dichroic compound 31 is usually higher than the nematic transition temperature Tne of the liquid crystalline polymer 21. For this reason, when the 1st heating part 101 makes the dry coating film 97 1st temperature T1, it will exceed the nematic transition temperature Tne of the liquid crystalline polymer 21 automatically.

When the melting point Tm of the dichroic compound 31 is lower than the nematic transition temperature Tne of the liquid crystalline polymer 21 due to a specific combination of the liquid crystalline polymer 21 and the dichroic compound 31, the first temperature T1 is a temperature higher than the nematic transition temperature Tne of the liquid crystalline polymer 21. That is, the first temperature T1 is at least higher than the melting point Tm of the dichroic compound 31 and higher than the nematic transition temperature Tne of the liquid crystalline polymer 21.

The first temperature T1 needs to be lower than the melting point (not shown) of the liquid crystalline polymer 21. When the melting point of the liquid crystalline polymer 21 is exceeded, the dried coating film 97 is melted and the film state cannot be maintained. As a result, the coated optical film 14 cannot be formed from the dried coating film 97. . Similarly, the first temperature T1 is a temperature at which the substrate 11, the first protective layer 12, or the alignment film 13 is damaged (for example, melting, deformation, or alteration (the alignment film 13 loses the direction of isomerization). It is necessary that the temperature be lower than the temperature at which Furthermore, the first temperature T1 needs to be lower than the transition temperature to another phase such as the phase transition temperature (not shown) of the liquid crystalline polymer 21 to the smectic phase. That is, the first temperature T1 is a temperature at which the liquid crystalline polymer 21 exhibits a nematic phase.

More specifically, the first heating step P1 preferably includes a temperature raising step P1a and a temperature maintaining step P1b. The temperature raising step P1a is a step in which a practical temperature rise change up to the first temperature T1 is generated and the dry coating film 97 having a temperature lower than the first temperature T1 is first raised to the first temperature T1. The temperature maintenance process P1b is a process of maintaining the dry coating film 97 that has reached the first temperature T1 at the first temperature T1.

The reason why the dry coating film 97 is set to the first temperature T1 is that the liquid crystalline polymer 21 and the dichroic compound 31 are compatible by making the liquid crystalline polymer 21 into a nematic phase and melting the dichroic compound 31. It is for making it into a state. Therefore, if this state can be created, the specific temperature rise profile when the dry coating film 97 is set to the first temperature T1 is arbitrary. For example, in the temperature profile of FIG. 8, the temperature raising step P1a linearly raises the temperature of the dry coating film 97 at a constant rate of temperature rise from the elapsed time t1 to the elapsed time t2, but the temperature raising step P1a The temperature may be raised stepwise up to one temperature T1 or along a curve of an arbitrary shape.

In the temperature maintaining step P1b, the first temperature T1 is almost completely maintained from the elapsed time t2 to the elapsed time t3, but it is only necessary to maintain a temperature equal to or higher than the first temperature T1. That is, “maintaining the first temperature T1” means “maintaining a temperature higher than the melting point Tm of the dichroic compound 31 and higher than the nematic transition temperature Tne of the liquid crystalline polymer 21”. The temperature range in which the other layers or films such as the coating optical film 14 and the alignment film 13 are free from defects, the liquid crystalline polymer 21 exhibits a nematic phase, and the compatibility between the liquid crystalline polymer 21 and the dichroic compound 31 can be continued. It means that the temperature of the dried coating film 97 is maintained inside. Therefore, the temperature maintaining step P1b does not need to strictly continue the first temperature T1, and there may be a temperature change of the dry coating film 97 in the temperature maintaining step P1b.

The time required for the temperature raising step P1a (Δt ₂₁ = t2-t1), the time required for the temperature maintaining step P1b (Δt ₃₂ = t3-t2), and the time required for the entire first heating step P1 (Δt ₃₁ = t3− t1) can be adjusted according to the material of each part constituting the liquid crystalline polymer 21, the dichroic compound 31, and the other intermediate laminate 110. In the temperature maintaining step P1b, the actual liquid crystal polymer 21 exhibits a nematic phase in the entire dry coating film 97, and is a practical requirement for realizing a state in which the liquid crystal polymer 21 and the dichroic compound 31 are compatible. It is sufficient to maintain the first temperature T1 for a long time. The time for maintaining the first temperature T1 depends on the material of each part constituting the liquid crystalline polymer 21, the dichroic compound 31, and the other intermediate laminate 110, and is, for example, about several seconds to several tens of seconds. The time is preferably from 19 seconds to 19 seconds, more preferably from 15 seconds to 15 seconds, and particularly preferably from 9 seconds to 11 seconds. In the present embodiment, the time for maintaining the first temperature T1 is 10 seconds.

When the first heating unit 101 heats the dry coating film 97, in the state where the temperature of the dry coating film 97 is lower than the nematic transition temperature Tne of the liquid crystalline polymer 21, as shown in FIG. The liquid crystalline polymer 21 and the dichroic compound 31 are solidified in a state of being arranged almost randomly. Thereafter, when the dry coating film 97 reaches the first temperature T1, as shown in FIG. 10, the liquid crystalline polymer 21 increases the fluidity to exhibit a nematic phase, and is aligned approximately in accordance with the alignment film 13. On the other hand, when the dried coating film 97 reaches the first temperature T1, the dichroic compound 31 melts and is compatible with the liquid crystalline polymer 21, but the liquid crystalline polymer 21 has an orientation generally in accordance with the alignment film 13. Therefore, as a result, it becomes easy to gather between the mesogenic groups 23.

The first cooling unit 102 cools the dried coating film 97 that has undergone the first heating step P1, and changes the first temperature T1 to a second temperature T2 that is lower than at least the crystallization temperature Tc of the dichroic compound 31. Cooling process P2 (cooling process) is performed. More preferably, the second temperature T2 is a temperature lower than the crystallization temperature Tc of the dichroic compound 31 and lower than the crystallization temperature Ts of the liquid crystalline polymer 21. In the present embodiment, the second temperature T2 is a temperature lower than the crystallization temperature Tc of the dichroic compound 31 and lower than the crystallization temperature Ts of the liquid crystalline polymer 21.

The crystallization temperature Tc of the dichroic compound 31 is usually lower than the nematic transition temperature Tne of the liquid crystalline polymer 21. For this reason, when the 1st cooling part 102 makes the dry paint film 97 2nd temperature T2, it is automatically lower than the nematic transition temperature Tne of the liquid crystalline polymer 21. In general, since the crystallization temperature Ts of the liquid crystalline polymer 21 is lower than the crystallization temperature Tc of the dichroic compound 31, the first cooling unit 102 is in the process of setting the dry coating film 97 to the second temperature T2. The dichroic compound 31 is crystallized before the liquid crystalline polymer 21.

Due to the specific combination of the liquid crystalline polymer 21 and the dichroic compound 31, the level relationship between the crystallization temperature Ts of the liquid crystalline polymer 21 and the crystallization temperature Tc of the dichroic compound 31 is as described above. It may reverse. Also in this case, the second temperature T2 is a temperature lower than at least the crystallization temperature Tc of the dichroic compound 31. That is, the second temperature T2 needs to be at least lower than the crystallization temperature Tc of the dichroic compound 31, but is not necessarily lower than the crystallization temperature Ts of the liquid crystalline polymer 21. In the first cooling step P2, the liquid crystalline polymer 21 includes one or a plurality of dichroic compounds 31 in the voids 26 formed as a result of regular alignment according to the alignment film 13, and dichroism. This is because the compound 31 only needs to be able to suppress movement such as movement or rotation while maintaining a substantially constant orientation in the constant gap 26 formed by the liquid crystalline polymer 21.

The first cooling step P2 is a step of rapidly cooling the dried coating film 97. For this reason, in the first cooling step P2, the dried coating film 97 is cooled at a cooling rate equal to or higher than a predetermined cooling rate, or the dried coating film 97 is cooled within a predetermined time from the first temperature T1 to the second temperature T2. To do. The cooling rate is a rate of temperature decrease that lowers (ie, decreases) the temperature. For example, the cooling rate of 3 ° C./second means that the temperature is lowered by 3 ° C. per second.

Specifically, the first cooling step P2 is performed by dry coating at a cooling rate (hereinafter referred to as a predetermined cooling rate) of at least 1 ° C./second or more, more preferably 3 ° C./second or more, particularly preferably 5 ° C./second or more. The membrane 97 is cooled. In the present embodiment, for simplicity, the dichroic compound 31 is crystallized at the crystallization temperature Tc. More practically, the dichroic compound 31 is in a predetermined temperature range (hereinafter, Crystallization occurs in the crystallization temperature range. The upper limit temperature of the crystallization temperature range (that is, the temperature at which crystallization of the dichroic compound 31 starts during cooling) is “Tc1”, and the lower limit temperature of the crystallization temperature range (that is, the crystal of the dichroic compound 31) When the temperature at which crystallization is completed is “Tc2”, at least the cooling rate from the upper limit temperature Tc1 of the crystallization temperature range to the lower limit temperature Tc2 of the crystallization temperature range is a predetermined cooling rate. preferable. The predetermined cooling rate is a so-called average rate. For this reason, it may include time for cooling at a cooling rate lower than a predetermined cooling rate in a part of the process of cooling the dry coating film 97. In this case, the cooling rate averaged in any one of the temperature sections may be a predetermined cooling rate. There is basically no upper limit to the cooling rate in the first cooling step P2. For this reason, it is preferable to cool as fast as possible if each part of the intermediate | middle laminated body 110 which has the dry coating film 97 changes in quality, or it is in the range which does not produce defects, such as wrinkles (wrinkles).

In the first cooling step P2, the dry coating film 97 is applied from the first temperature T1 to the second temperature T2, within 0.01 seconds to 110 seconds, preferably within 0.01 seconds to 40 seconds, more preferably The dried coating film 97 is cooled within 0.01 seconds to 25 seconds, particularly preferably within 0.01 seconds to 10 seconds. More practically, the time required to reach at least the upper limit temperature Tc1 of the crystallization temperature range and the lower limit temperature Tc2 of the crystallization temperature range may be 0.01 seconds or more and 40 seconds or less. The time is more preferably from 01 seconds to 20 seconds, and particularly preferably from 0.01 seconds to 10 seconds.

In the first cooling step P2, it is only necessary that the dry coating film 97 can be cooled at least within the predetermined cooling rate or within the predetermined time, and the dry coating film 97 is cooled within the predetermined cooling rate and within the predetermined time. It is preferable. In addition, when the predetermined cooling rate or the predetermined time is observed, a specific cooling profile in the first cooling step P2 is arbitrary. For example, in FIG. 8, in the first cooling step P2, the temperature of the dry coating film 97 is linearly decreased at a constant cooling rate from the elapsed time t3 to the elapsed time t4, but the first cooling step P2 is performed at the second temperature. The temperature may be lowered stepwise up to T2 or along a curve of an arbitrary shape. In addition, the first cooling step P2 may include a part of the time period during which the temperature of the dry coating film 97 does not decrease (maintain a constant temperature, etc.). Moreover, the 1st cooling process P2 may have the time slot | zone when the temperature of the dry coating film 97 rises in a part. As described above, in the first cooling process P2, when the temperature is lowered stepwise or along a curve of an arbitrary shape, or part of the time period during which the temperature of the dried coating film 97 does not decrease or the temperature of the dried coating film 97 When the time zone during which the temperature rises is included, the lowest temperature reached in the first cooling step P2 is the second temperature T2.

Further, the first cooling process P2 is the next process of the first heating process P1. That is, after the first heating step P1 and before the start of the first cooling step P2, the first step without the step with the temperature change of the dry coating 97 and the other step with the change in the state of the dry coating 97 are not performed. The first cooling step P2 is performed immediately after the heating step P1.

When the first cooling unit 102 cools the dry coating film 97, the liquid crystalline polymer 21 is solidified while the mesogenic group 23 approaches the regular alignment state according to the alignment film 13 more accurately as shown in FIG. Thus, the air gap 26 is further clarified. On the other hand, the dichroic compound 31 follows the alignment direction of the mesogenic groups 23 in the voids 26 and is solidified while maintaining a substantially constant alignment state, and is in a phase-separated state with respect to the liquid crystalline polymer 21. As a result, the dried coating film 97 has a function as a uniform polarizer as a whole.

As described above, in the first cooling step P2, the dichroic compound 31 trapped in the void 26 destroys the void 26 or is bonded to another void 26, for example. The reason why the crystallization is performed while maintaining the arrangement order according to the voids 26 formed by the mesogenic groups 23 and the like without crystal growth with random orientation is because the dried coating film 97 is rapidly cooled in the first cooling step P2. It is. Further, in the first cooling step P2, the liquid crystalline polymer 21 is solidified while the mesogenic group 23 approaches the regular alignment state according to the alignment film 13 more accurately. It is because it cools quickly.

The 2nd heating part 103 performs the 2nd heating process P3 which heats the dry paint film 97 which passed through the 1st cooling process P2, and makes it the 3rd temperature T3. The third temperature T3 is at least lower than the nematic transition temperature Tne of the liquid crystalline polymer 21. Further, the third temperature T3 is preferably lower than the crystallization temperature Tc of the dichroic compound 31. The crystallization temperature Ts of the liquid crystalline polymer 21 is lower than the nematic transition temperature Tne, and the third temperature T3 is at least higher than the crystallization temperature Ts of the liquid crystalline polymer 21. The third temperature T3 is a temperature in the temperature range where the association of the dichroic compound 31 is promoted (hereinafter referred to as the association promotion temperature range) RT or higher. Therefore, the second heating step P3 promotes the association of the plurality of dichroic compounds 31 included in one void 26 formed by the liquid crystalline polymer 21. When association-accelerating temperature range RT is X ₁ ° C. or more X ₂ ° C. or less, and the meeting promotes temperature range RT or higher, at least X ₁ ° C. or higher, X ₁ ° C. or more X ₂ ° C. below the temperature The temperature may be X ₂ ° C or higher.

More specifically, the second heating step P3 preferably includes a temperature raising step P3a and a temperature maintaining step P3b. The temperature raising step P3a is a step in which a practical temperature increase up to the third temperature T3 is generated, and the dry coating film 97 is first heated to the third temperature T3. The temperature maintaining step P3b is a step of maintaining the dry coating film 97 that has reached the third temperature T3 at the third temperature T3.

The reason why the dry coating film 97 is set to the third temperature T3 is to promote the association of the dichroic compound 31, and therefore the specific temperature rise profile when the dry coating film 97 is set to the third temperature T3 is arbitrary. It is. For example, in the temperature profile of FIG. 8, the temperature raising step P3a linearly raises the temperature of the dry coating film 97 at a constant rate of temperature rise from the elapsed time t5 to the elapsed time t6. The temperature can be raised stepwise up to 3 temperatures T3 or along a curve of an arbitrary shape.

However, in the second heating step P3, it is preferable to heat the dried coating film 97 that has undergone the first cooling step P2 at a predetermined heating rate (hereinafter referred to as a predetermined heating rate). The heating rate is a rate of temperature increase that raises the temperature (that is, increases the temperature). For example, a heating rate of 3 ° C./second means that the temperature is increased by 3 ° C. per second.

Specifically, the predetermined heating rate is, for example, 0.1 ° C./second or more and 3.0 ° C./second or less, and more preferably 0.5 ° C./second or more and 2.0 ° C./second or less. Since it takes time for the dichroic compound 31 to form the association body 32, if the heating rate is high, a sufficient association body cannot be formed, and the degree of orientation decreases. Further, when the heating rate is slow, the process length becomes long and the process load increases. The predetermined heating rate is a so-called average rate. For this reason, in the part of the process which heats the dry coating film 97 which passed through the 1st cooling process P2, the time heated at the heating rate outside the range of the predetermined heating rate may be included. For example, the heating rate averaged in the temperature raising step P3a may be a predetermined heating rate.

In addition, the temperature maintaining step P3b schematically maintains the third temperature T3 almost completely from the elapsed time t6 to the elapsed time t7, but it is only necessary to maintain at least a temperature higher than the association promotion temperature range RT. That is, “maintaining the third temperature T3” means maintaining a temperature not lower than the association promotion temperature range RT. Therefore, the temperature maintaining process P3b does not need to strictly maintain a specific temperature (the third temperature T3 set as a target for temperature increase), and there may be a temperature change of the dry coating film also in the temperature maintaining process P3b. .

Time required for the temperature raising step P3a (ΔT ₆₅ = t6−t5), time required for the temperature maintaining step P3b (ΔT ₇₆ = t7−t6), and time required for the entire second heating step P3 (ΔT ₇₅ = t7− t5) can be adjusted according to the material of each part constituting the liquid crystalline polymer 21, the dichroic compound 31, and the other intermediate laminate 110. In the temperature maintaining step P3b, the liquid crystal polymer 21 does not break the alignment state according to the alignment film 13 and the association of the dichroic compound 31 is substantially completed in the entire dry coating film 97. It is only necessary to maintain the third temperature T3 for a long time. Note that the second heating step P3 is performed in the temperature maintaining step P3b and / or the temperature raising step P3a, depending on the liquid crystal polymer 21, the dichroic compound 31, and other materials constituting the intermediate laminate 110. The third temperature T3 is preferably maintained continuously or intermittently for at least 1 second or more, and more preferably maintained for 3 seconds or more.

When the second heating unit 103 heats the dried coating film 97, the mesogenic group 23 of the liquid crystalline polymer 21 is gradually maintained while generally maintaining the alignment state of the liquid crystalline polymer 21 and the dichroic compound 31 (see FIG. 11). Gain some mobility. As a result, the mesogenic group 23 follows the alignment film 13 better. Further, the dichroic compound 31 obtains mobility when the crystallization temperature Tc exceeds the crystallization temperature Tc and becomes a temperature equal to or higher than the association promotion temperature range RT, but the gap 26 formed by the mesogenic group 23 and the like is not removed and the same. The probability of contact with another dichroic compound 31 in the void 26 is increased. As a result, the association of the dichroic compound 31 proceeds in each gap 26, and the degree of orientation of the dried coating film 97 is improved (see FIG. 2).

The second cooling unit 104 performs a second cooling step P4 that cools the dried coating film 97 that has undergone the second heating step P3 naturally or actively by blowing air or the like. In the second cooling step P4, the dried coating film 97 is brought to a temperature such as room temperature To or room temperature, for example. The dried coating film 97 that has undergone the second cooling step P4 becomes the coated optical film 14 having a high degree of orientation while maintaining a good polarizer state with improved polarization degree (see FIG. 6).

The first heating unit 101, the first cooling unit 102, the second heating unit 103, and the second cooling unit 104 constituting the temperature management unit 93 are, for example, a conveyance roller with a temperature adjustment function as shown in FIG. (Hereinafter referred to as a temperature control roller) 116 and a temperature control unit 117. The temperature control roller 116 adjusts the temperature of the contact surface with the intermediate laminate 110 by passing oil or the like whose temperature has been adjusted by the temperature control unit 117 inside. In addition, the temperature control roller 116 is a drive roller having a rotation control unit in the present embodiment. However, the temperature control roller 116 may be a driven roller that rotates by contact with the conveyed intermediate laminate 110. In the present embodiment, the contact area of the intermediate laminate 110 with respect to the peripheral surface of the temperature control roller 116 is increased by sucking the atmosphere below the paper surface of FIG. I am letting. Thereby, the intermediate | middle laminated body 110 can be heated or cooled more rapidly and uniformly.

As shown in FIG. 13, the second protective layer forming unit 44 includes a coating film forming unit 121 and a drying unit 122. The coating film forming unit 121 applies a coating liquid 126 containing an epoxy monomer polymer that is a material of the second protective layer 15 and a solvent that dissolves the epoxy monomer polymer onto the coating optical film 14. Application is performed to form a coating film 127. Thereafter, the drying unit 122 reduces the solvent from the coating film 127 by heating, blowing, natural drying, and / or other methods, and the coating film 127 is dried, so that the second protective layer 15 is formed on the coated optical film 14. Form. Thereby, the laminated body 10 is completed.

As described above, the manufacturing apparatus 41 includes the liquid crystalline polymer 21 and the dichroic compound 31, and when forming the coating optical film 14 that expresses the function as a polarizer by the orientation of the dichroic compound 31, Since the 1st heating process P1 and the 1st cooling process P2 are performed, the laminated body 10 which has the coating optical film 14 with high orientation degree and the coating optical film 14 with high orientation degree can be obtained. In addition, when the dichroic compound 31 has an associative property, the coating optical film 14 and the laminated body in which the dichroic compound 31 forms the associated body 32 and the degree of orientation is further improved by performing the second heating step P3. 10 is obtained.

In the above-described embodiments and examples, the coating optical film 14 is formed by using the liquid crystalline polymer 21 and one type of dichroic compound 31, but the coating optical film 14 has two or more types. The dichroic compound 31 can be contained.

Since the dichroic compound 31 has different wavelength bands of light to be absorbed depending on the type, when the coating optical film 14 contains two or more types of dichroic compounds 31, only one type of dichroic compound 31 is used. The wavelength band in which the laminate 10 functions as a polarizing plate can be made wider than in the case. When manufacturing the laminated body 10 which functions as a polarizing plate in the wavelength band of visible light, it is preferable that at least one type contains the dichroic compound 31 that mainly absorbs the green wavelength band. It is particularly preferable that the dichroic compound 31 that absorbs the green wavelength band has association properties. This is because green has higher visibility than blue or red.

When the coating optical film 14 contains two or more kinds of dichroic compounds 31, it is preferable that at least one kind contains the dichroic compounds 31 having associative properties. This is because the degree of orientation is particularly easily improved by promoting the association by performing the second heating step P3. However, even when the coating optical film 14 contains only one type or a plurality of types of dichroic compounds 31 that do not have associative properties, the dichroism is obtained through the first heating step P1 and the first cooling step P2. The compound 31 can obtain a certain orientation. Even when the coating optical film 14 contains only one or a plurality of types of dichroic compounds 31 having no associative properties, the orientation degree of the liquid crystalline polymer 21 is improved by performing the second heating step P3. Therefore, the degree of orientation of the dichroic compound 31 is improved following the improvement of the degree of orientation of the liquid crystalline polymer 21.

When the coating optical film 14 contains two or more dichroic compounds 31, the first temperature T1 is set to a temperature higher than the maximum value of the melting point Tm of the dichroic compound 31. This is because all the dichroic compounds 31 are melted. In the first cooling step P2, the second temperature T2 is set to a temperature lower than at least the minimum value of the crystallization temperature Tc of the dichroic compound 31. This is because all the dichroic compounds 31 are solidified to suppress motility. However, in many cases, since the crystallization temperature Ts of the liquid crystalline polymer 21 is lower than the crystallization temperature Tc of the dichroic compound 31, the second temperature is lower than the crystallization temperature Ts of the liquid crystalline polymer 21. By setting T2, all the dichroic compounds 31 can be solidified. In the second heating step P3, the third temperature is set to a value lower than the lowest value of the crystallization temperature Tc of the associative dichroic compound 31 and lower than the nematic transition temperature Tne of the liquid crystalline polymer 21. Set T3. This is because the dichroic compound 31 having all the associative properties is given motility and the association is promoted with the positional restriction in the void 26 being imposed.

[Example]
Using the manufacturing apparatus 40, the cooling conditions in the first cooling step P2 were changed to the conditions shown in Table 1, and the stacked body 10 of the example and the stacked body of the comparative example were manufactured. The laminated body 10 of each example and the laminated body of each comparative example have the same manufacturing conditions and configuration other than the conditions shown in Table 1. Specifically, the substrate 11 is formed of a TAC film, the first protective layer 12 is formed of PVA, the alignment film 13 is a photo-alignment film using azobenzene, and the second protective layer 15 is an epoxy-based film. It is a monomer polymer. The liquid crystalline polymer 21 used for the coating optical film 14 is L1 below. The liquid crystalline polymer 21 of L1 is composed of a repeating unit represented by (1) and a repeating unit represented by (2). The ratio of the repeating unit represented by (1) and the repeating unit represented by (2) in one molecule is {repeating unit represented by (1)}: {repeating unit represented by (2)} = 80:20. The liquid crystalline polymer 21 of the following L1 has a nematic transition temperature Tne of about 97 ° C. and a crystallization temperature Ts of about 67 ° C. The dichroic compound 31 used for the coating optical film 14 is D1 below. The following dichroic compound 31 of D1 has a melting point Tm of about 140 ° C. and a crystallization temperature Tc of about 85 ° C. The heating rate in the second heating step P3 is about 2.0 ° C./second, and the heating time is at least 1 second. Further, the association promotion temperature range RT of the dichroic compound 31 shown in D1 below is about 50 ° C. or higher and about 80 ° C. or lower. The parentheses () written in the “presence / absence of maintenance step” column of Table 1 is the time during which the first temperature T1 was maintained.

Moreover, the laminated body 10 of an Example and the laminated body of a comparative example were evaluated using the orientation degree by the following method.
<Measurement method of orientation degree>
The second protective layer 15 was peeled from the obtained laminate 10. Then, in a state where a linear polarizer is inserted on the light source side of an optical microscope (manufactured by Nikon Corporation, product name “ECLIPSE E600 POL”), “laminate with the second protective layer 15 peeled off” on the sample base in the examples and comparative examples The body 10 ”was set, the absorbance in the wavelength region of 400 to 700 nm was measured using a multi-channel spectrometer (product name“ QE65000 ”manufactured by Ocean Optics), and the degree of orientation was calculated by the following formula. The results are shown in Table 1 below.
Orientation degree: S = [(Az0 / Ay0) -1] / [(Az0 / Ay0) +2]
Az0: Absorbance with respect to polarized light in the direction of absorption axis Ay0: Absorbance with respect to polarized light in the direction of polarization axis <Evaluation Method>
An orientation degree of 0.95 or more was evaluated as A, an orientation degree of less than 0.95 and 0.92 or more was evaluated as B, and an orientation degree of less than 0.92 was defined as C. In terms of the degree of orientation, evaluation A and evaluation B are acceptable, and evaluation C is unacceptable.

DESCRIPTION OF SYMBOLS 10 Laminated body 11 Base material 12 1st protective layer 13 Orientation film 14 Coating optical film 15 2nd protective layer 21 Liquid crystalline polymer 22 Main chain 23 Mesogenic group 24 Side chain 26 Space | gap 31 Dichroic compound 32 Aggregate 40 Production apparatus 41 First protective layer forming part 42 Alignment film forming part 43 Coating optical film forming part 44 Second protective

layer forming part

51, 61, 91 Coating

film forming part

52, 62, 92 Drying part 53, 66, 94

Coating liquid

54, 67 , 96 Coating film 63

Light irradiation part

68, 97 Dry coating film 93 Temperature management part 101 1st heating part 102 1st cooling part 103 2nd heating part 104 2nd cooling part 110 Intermediate laminated body A, B Evaluation of orientation degree Dc Transport direction P1 First heating step P1 First cooling step P1a, P3a Temperature rising step P1b, P3b Temperature maintaining step P2 First cooling step P3 Second heating step t1 to t8 Elapsed time 1 First temperature T2 Second temperature T3 Third temperature Tc Crystallization temperature of dichroic compound Tm Melting point of dichroic compound Tne Nematic transition temperature of liquid crystalline polymer To Room temperature Ts Crystallization temperature of liquid crystalline polymer RT Association promotion temperature range

Claims

A coating film forming step of forming a coating film by applying a coating liquid containing a liquid crystalline compound, a dichroic compound, and a solvent for dissolving the liquid crystalline compound and the dichroic compound on the alignment film. When,
A drying step of reducing the solvent from the coating film;
A first heating step of heating the coating film in which the solvent is reduced to a first temperature higher than the melting point of the dichroic compound;
The coating film that has undergone the first heating step is cooled, and from the first temperature to a second temperature that is lower than the crystallization temperature of the dichroic compound and lower than the crystallization temperature of the liquid crystalline compound. Cooling process to
A second heating step of heating the coating film that has undergone the cooling step to a third temperature that is lower than the nematic transition temperature of the liquid crystalline compound;
The manufacturing method of the laminated body which has this.
The method for producing a laminate according to claim 1, wherein when the dichroic compound has associative properties, the third temperature is equal to or higher than an association promotion temperature range that promotes association of the dichroic compound.
The method for producing a laminate according to claim 1 or 2, wherein the third temperature is higher than at least a crystallization temperature of the liquid crystal compound.
The method for producing a laminate according to any one of claims 1 to 3, wherein the third temperature is lower than a crystallization temperature of the dichroic compound.
5. The method according to claim 1, wherein the second heating step heats the coating film that has undergone the cooling step at a heating rate of 0.1 ° C./second or more and 3.0 ° C./second or less. A manufacturing method of a layered product.
The method for manufacturing a laminated body according to any one of claims 1 to 5, wherein, in the second heating step, the third temperature T3 is maintained for 1 second or longer.