JP3213762B2 - Manufacturing method of heat resistant optical element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a heat-resistant optical element made of a liquid crystalline polymer useful in displays, optoelectronics, and optics.

[0002]

2. Description of the Related Art Liquid crystalline polymers have optical anisotropy,
It is known that various molecular orientation structures can be obtained as compared with general polymers, and these structures can be immobilized and used as various optical elements. In particular, an optical element having a twisted structure inside a film can be achieved only by an optical element using a liquid crystalline polymer, and an optical element having characteristics that cannot be obtained by conventional optical elements can be manufactured. The present inventors have heretofore described a compensator for a liquid crystal display element having a twisted structure inside a film (Japanese Patent Application Laid-Open No. 3-87720) and an optical rotatory optical element (Japanese Patent Application No. 126962). These optical elements are epoch-making, having high performance that could not be achieved by conventional optical elements. However, these optical elements are stable when no external force is applied because the liquid crystalline polymer has fluidity at high temperatures. The alignment structure of the optical element was destroyed, and the predetermined optical performance could not be maintained, and as a result, the use environment conditions of the optical element, the secondary processing conditions, the incorporation conditions into the device, and the like were limited. For this reason, it has been difficult to apply conventional optical devices using liquid crystalline polymers to in-vehicle display devices and projection-type liquid crystal display devices that require high heat resistance in the usage environment. In the manufacturing process of an optical device or a display device using an optical element using the method, there is a problem that the maximum temperature in the process is limited.

[0003]

SUMMARY OF THE INVENTION The present inventors have conducted intensive studies on means for solving such a problem of an optical element using a liquid crystalline polymer, and as a result, it has been found that such a problem has been solved. Since the liquid crystalline polymer must be oriented during the fabrication of the device, it must be used in a state of high fluidity.On the other hand, after the alignment is completed, the fluidity of the polymer liquid crystal must be kept low. We focused on what would happen. That is, if a heat treatment is performed during the alignment treatment of the liquid crystalline polymer or after the alignment is fixed, the liquid crystalline polymer can be aligned, and the fluidity of the polymer liquid crystal can be reduced while maintaining the alignment structure, thereby imparting heat resistance to the optical element. And finally completed the present invention.

[0004]

That is, the present invention provides a light-transmitting substrate, an alignment film formed on the substrate, and nematic alignment or twisted nematic alignment in a liquid crystal state formed on the alignment film, In a method for producing an optical element comprising a film of a liquid crystalline polymer which is thermally polymerized to be in a glassy state below a liquid crystal transition point, the liquid crystalline polymer layer is subjected to alignment treatment and / or after alignment is fixed. The present invention relates to a method for producing a heat-resistant optical element, wherein a heat treatment is performed at a temperature at which polymerization proceeds. According to the method for producing a heat-resistant optical element of the present invention, a liquid crystalline polymer is used in a state of high fluidity and high orientation at the time of alignment treatment, so that heat resistance can be imparted to the optical element while maintaining high optical performance.

Hereinafter, the present invention will be described in detail. It is essential that the polymer liquid crystal used for the optical element has the following properties. In order to stably fix the nematic alignment or the twisted nematic alignment, it is important not to have a crystal phase in a lower temperature part than the nematic phase or the twisted nematic phase in the liquid crystal phase series. If a crystalline phase is present, it will necessarily pass through the crystalline phase when cooled for immobilization, resulting in the destruction of the nematic or twisted nematic orientation once obtained. Therefore, it is essential that the polymer liquid crystal used for this purpose not only has good orientation due to the interface effect, but also has a glass phase in a lower temperature part than the nematic phase or the twisted nematic phase. Further, in order to suppress the flow of the polymer liquid crystal by the heat treatment and improve the heat resistance, the polymer liquid crystal needs to be thermally polymerized. Here, thermal polymerization refers to polycondensation by heat and crosslinking by heat.

There are two types of polymer liquid crystals that are twisted nematically aligned: a polymer having an optically active group itself and a polymer having a twisted nematic liquid crystallinity as a mixture of a base polymer having no optically active group and another optically active compound. is there. As the polymer to be used, any thermopolymerizable polymer liquid crystal which is in a nematic alignment or a twisted nematic alignment in a liquid crystal state and is in a glassy state at or below a liquid crystal transition point can be used. Examples of the nematic alignment include a main chain type liquid crystal polymer such as polyester, polyamide, and polyesterimide. In the case of twisted nematic alignment, a main chain type liquid crystal polymer such as optically active polyester, polyamide, or polyesterimide, or a main chain type liquid crystal polymer such as polyester, polyamide, or polyesterimide that is not optically active, or other low molecular weight or high molecular weight. Examples thereof include a polymer to which a molecular optically active compound is added. Among them, polyester is preferred from the viewpoint of ease of synthesis, orientation, glass transition point and the like. As the polyester used, a polymer containing an ortho-substituted aromatic unit as a constituent component is most preferable, but an aromatic having a bulky substituent in place of the ortho-substituted aromatic unit, or an aromatic having a fluorine or fluorine-containing substituent, or the like. Polymers containing as a component can also be used. The ortho-substituted aromatic unit referred to in the present invention means a structural unit in which a bond constituting a main chain is ortho-positioned to each other.

[0007] Examples of these are:

Embedded image (X represents hydrogen, a halogen such as Cl or Br, an alkyl group or an alkoxy group having 1 to 4 carbon atoms, or a phenyl group, and k is 0 to 2). Of these, particularly preferred examples include the following.

[0008]

Embedded image (Me; methyl group, Et; ethyl group, Bu; butyl group)

The polyester used in the present invention includes (a) a structural unit derived from a diol (hereinafter, referred to as a structural unit).
A structural unit derived from a diol component) and a dicarboxylic acid (hereinafter, referred to as a dicarboxylic acid component) and / or (b) a structural unit derived from an oxycarboxylic acid containing both a carboxylic acid and a hydroxyl group in one unit (hereinafter, referred to as a dicarboxylic acid component). Oxycarboxylic acid component) as a constituent component, and preferably further includes the above-mentioned ortho-substituted aromatic unit.

Among these, examples of the diol component include the following aromatic and aliphatic diols.

Embedded image (Y is hydrogen, halogen such as Cl, Br, etc., having 1 to 4 carbon atoms.
Represents an alkyl group or an alkoxy or phenyl group. l is 0-2. )

Embedded image (N represents an integer of 2 to 12)

Embedded image Especially

Embedded image And the like are preferably used.

The following can be exemplified as the dicarboxylic acid component.

Embedded image (Z represents a hydrogen atom, a halogen atom such as Cl or Br, an alkyl group having 1 to 4 carbon atoms, an alkoxy group or a phenyl group; m is 0 to 2);

Embedded image Above all,

Embedded image Are preferred.

Specific examples of the oxycarboxylic acid component include the following units.

Embedded image The molar ratio between dicarboxylic acid and diol is approximately 1: 1 as in general polyester (when oxycarboxylic acid is used, the ratio of carboxylic acid groups to hydroxyl groups). The proportion of the ortho-substituted aromatic unit in the polyester is usually preferably in the range of 5 mol% to 40 mol%, and more preferably in the range of 10 mol% to 30 mol%. If the amount is less than 5 mol%, a crystal phase tends to appear below the nematic phase, which is not preferable. If it is more than 40 mol%, the polymer tends to exhibit no liquid crystallinity, which is not preferable. The following polymers can be exemplified as typical polyesters.

[0013]

Embedded image A polymer composed of structural units of

Embedded image A polymer composed of structural units of

Embedded image A polymer composed of structural units of

Embedded image A polymer composed of structural units of

Embedded image A polymer composed of structural units of

Embedded image A polymer composed of structural units of

Embedded image A polymer composed of structural units of

Embedded image A polymer composed of the structural units of

In place of the ortho-substituted aromatic units, the following polymers having aromatic units containing bulky substituents or aromatic units containing fluorine or fluorine-containing substituents are also preferably used.

Embedded image

Embedded image The molecular weight of these polymers can be determined in various solvents, for example, phenol / tetrachloroethane (60/40 (weight ratio)).
The logarithmic viscosity measured at 30 ° C. in a mixed solvent is usually 0.05
To 3.0, more preferably 0.07 to 2.0. When the logarithmic viscosity is smaller than 0.05, the strength of the obtained polymer liquid crystal becomes weak, which is not preferable. On the other hand, if it is larger than 3.0, the viscosity at the time of liquid crystal formation is too high, causing problems such as a decrease in alignment and an increase in the time required for alignment.

The method for synthesizing these polymers is not particularly limited, and they are synthesized by a polymerization method known in the art, for example, a melt polymerization method or an acid chloride method using a corresponding acid chloride of dicarboxylic acid. In the case of synthesis by the acid chloride method , for example, the corresponding acetylated product of the corresponding dicarboxylic acid and the corresponding diol can be produced by polymerizing at high temperature and under high vacuum, and the molecular weight can be easily controlled by controlling the polymerization time or controlling the charge composition. . In order to accelerate the polymerization reaction, a conventionally known metal salt such as sodium acetate can be used. When the melt polymerization method is used, a desired polyester can be easily obtained by dissolving a predetermined amount of dicarboxylic acid dichloride and diol in a solvent and heating in the presence of an acid acceptor such as pyridine.

The optically active compounds to be mixed to impart a twist to these nematic liquid crystalline polymers will be described. A typical example is an optically active low molecular compound. Any compound having optical activity can be used in the present invention, but an optically active liquid crystalline compound is desirable from the viewpoint of compatibility with the base polymer. Specifically, the following compounds can be exemplified.

[0017]

Embedded image

Embedded image Cholesterol derivatives, etc.

The optically active compounds used in the present invention include the following optically active high molecular compounds. Any polymer compound having an optically active group in the molecule can be used, but a polymer compound exhibiting liquid crystallinity is desirable from the viewpoint of compatibility with the base polymer. Examples thereof include liquid crystalline polyacrylates, polymethacrylates, polymalonates, polysiloxanes, polyesters, polyamides, polyesteramides, polycarbonates, polypeptides, and celluloses having an optically active group. Above all, an aromatic-based optically active polyester is most preferable because of its compatibility with the base nematic liquid crystalline polymer. Specifically, the following polymers can be exemplified.

[0019]

Embedded image A polymer composed of structural units of

Embedded image A polymer composed of structural units of

Embedded image A polymer composed of (n = 2 to 12) structural units,

Embedded image A polymer composed of structural units of

Embedded image A polymer composed of structural units of

Embedded image A polymer composed of structural units of

Embedded image A polymer composed of structural units of

Embedded image A polymer composed of structural units of

Embedded image A polymer composed of structural units of

Embedded image A polymer composed of structural units of

Embedded image A polymer composed of the structural units of

The proportion of the optically active group in these polymers is usually 0.5 mol% to 80 mol%, preferably 5 mol% to 60 mol%. The molecular weights of these polymers are, for example, 0.05 to 5. 5 logarithmic viscosities measured in phenol / tetrachloroethane at 30 ° C.
A range of 0 is preferred. If the logarithmic viscosity is greater than 5.0, the viscosity is too high, which results in a decrease in the orientation, which is not preferred. If the logarithmic viscosity is less than 0.05, control of the composition becomes difficult, which is not preferred.

The heat-resistant optical element of the present invention also uses a polymer liquid crystal capable of forming a uniform, monodomain twisted nematic alignment by itself without using other optically active compounds, and of easily fixing the alignment state. It can also be manufactured by: It is essential that these polymers have an optically active group in the main chain and are themselves optically active, and specific examples thereof include main chain type liquid crystal polymers such as optically active polyesters, polyamides, and polyesterimides. be able to. Among them, polyester is preferred from the viewpoint of ease of synthesis, orientation, glass transition point and the like. As the polyester used, a polymer containing an ortho-substituted aromatic unit as a constituent component is most preferable, but an aromatic having a bulky substituent in place of the ortho-substituted aromatic unit, or an aromatic having a fluorine or fluorine-containing substituent, or the like. Polymers containing as a component can also be used. These optically active polyesters can be obtained by introducing the following optically active groups into the nematic liquid crystalline polyester described so far using an optically active diol, dicarboxylic acid or oxycarboxylic acid. (In the formula, * indicates optically active carbon)

[0022]

Embedded image

Embedded image Such.

The molecular weight of these polymers can be determined in various solvents such as phenol / tetrachloroethane (60/4
The logarithmic viscosity measured at 30 ° C in the mixed solvent of 0) is 0.0
It is preferably from 5 to 3.0, more preferably from 0.07 to 2.0. When the logarithmic viscosity is smaller than 0.05, the strength of the obtained polymer liquid crystal becomes weak, which is not preferable. On the other hand, if it is larger than 3.0, the viscosity at the time of forming the liquid crystal is too high, causing problems such as a decrease in the alignment and an increase in the time required for the alignment. Polymerization of these polymers can be carried out by a melt polycondensation method or an acid chloride method.

As representative examples of the liquid crystalline polymer of the present invention described above, specifically,

Embedded image (M / n = usually 99.9 / 0.1)
８０80/20, preferably 99.5 / 0.5 to 90/1
0, more preferably 99/1 to 95/5)

Embedded image (M / n = 0.5 / 99.5 to 10)
/ 90, preferably 1/99 to 5/95)

Embedded image (M / n = 0.5 / 99.5 to 10)
/ 90, preferably 1/99 to 5/95)

Embedded image (K = l + m + n, K / n = 99.
5 / 0.5 to 90/10, preferably 99/1 to 95
/ 5, 1 / m = 5/95 to 95/55)

Embedded image (K = l + m + n, K / n = 99.
5 / 0.5 to 90/10, preferably 99/1 to 95
/ 5, 1 / m = 5/95 to 95/55)

Embedded image (A) / (B) = Normal 9
9.9 / 0.1 to 80/20 (weight ratio), preferably 9
9.5 / 0.5 to 85/5, more preferably 99/1
~ 95/5, K = l + m, l / m = 75/25 to 25 /
75, P = q + r, p / q = 80 / 20-20 / 80) (A)

Embedded image (B) Polymer mixture represented by cholesteryl benzoate ((A) / (B) = usually 9)
9.9 / 0.1 to 70/30 (weight ratio), preferably 9
9.5 / 0.5 to 80/20, preferably 99/1 to 9
0/10, m = K + 1, K / 1 = 80/20 to 20/8
0)

Embedded image (A) / (B) = Normal 9
9.9 / 0.1 to 70/30 (weight ratio), preferably 9
9.5 / 0.5 to 80/20, preferably 99/1 to 9
0/10, K = 1 + m, 1 / m = 25 / 75-75 / 2
5, P = q + r, p / r = 20/80 to 80/20) (* mark indicates optically active carbon).

The method for producing a heat-resistant optical element comprising a liquid crystalline polymer according to the present invention basically comprises a light-transmitting substrate, an alignment film formed on the light-transmitting substrate, and a liquid crystal layer formed on the alignment film. In an optical element having a laminated structure of a polymer film, the liquid crystal polymer layer is subjected to a heat treatment at a temperature at which thermal polymerization of the liquid crystal polymer proceeds during the alignment treatment and / or after the alignment is fixed. As the light-transmitting substrate, glass, a light-transmitting plastic film, a plastic sheet, or the like can be used. Of these, the plastic substrate is preferably optically isotropic, for example, polymethyl methacrylate, polystyrene, polycarbonate,
Polyether sulfone, polyphenylene sulfide, polyolefin, epoxy resin, or the like can be used. As the alignment film, a rubbed polyimide film is preferably used, but an alignment film known in the art, such as an obliquely deposited silicon oxide film and a rubbed polyvinyl alcohol film, can of course be used. Further, a substrate obtained by directly rubbing a light-transmitting substrate is also used. A nematic polymer liquid crystal layer or a twisted nematic polymer liquid crystal layer is formed on the alignment film formed on the translucent substrate.

First, a nematic liquid crystal polymer or a twisted nematic liquid crystal polymer is dissolved in a solvent at a predetermined ratio to prepare a solution. The solvent used at this time varies depending on the type of polymer, but usually, ketones such as acetone, methyl ethyl ketone, and cyclohexanone; ethers such as tetrahydrofuran and dioxane; Hydrogen, a mixed solvent of these and phenol, dimethylformamide, dimethylacetamide,
Dimethyl sulfoxide, N-methylpyrrolidone and the like can be used. The concentration of the solution varies greatly depending on the viscosity of the polymer, but is usually used in the range of 5 to 50%, preferably in the range of 10 to 40%. This solution is then applied on a translucent glass plate, plastic plate or plastic film that has been subjected to an orientation treatment. The method of the alignment treatment is not particularly limited, but any method may be used as long as the liquid crystal molecules are aligned in parallel with the interface.For example, a polyimide rubbed glass or film obtained by applying polyimide on a substrate and rubbing is suitable. Used for

The coating method includes spin coating, roll coating, slot coating, slide coating,
A printing method, an immersion pulling method, or the like can be employed. After the application, the solvent is removed by drying, and heat treatment is performed at a predetermined temperature for a predetermined time to complete a monodomain nematic alignment or a twisted nematic alignment. When heat treatment for orientation and heat treatment for thermal polymerization are performed simultaneously, it is preferable that the heat treatment temperature is higher in order to assist the orientation by the interfacial effect and to promote the thermal polymerization. It is preferable that the heat treatment temperature is higher. However, if the temperature is too high, depending on the type of the polymer, an isotropic phase is present in a high-temperature portion, so that orientation cannot be obtained by heat treatment in this temperature range. According to the characteristics of the polymer as described above, it is preferable to perform the heat treatment at a temperature equal to or higher than the glass transition point but equal to or lower than the transition point to the isotropic phase, and at a temperature at which the polymerization of the polymer liquid crystal proceeds. Is preferably in the range of from 150 to 300 ° C. The time required to obtain sufficient alignment in the liquid crystal state on the alignment film and the time required to provide sufficient heat resistance depend on the composition, molecular weight and required heat resistance of the polymer, and are generally I can't say, but from 30 seconds to 120
Minutes is preferable, and particularly preferably 60 seconds to 100 minutes. If the time is shorter than 30 seconds, the orientation becomes insufficient,
Further, sufficient heat resistance is not provided. If the time is longer than 120 minutes, productivity is undesirably reduced. In order to provide sufficient heat resistance in a short heat treatment time, heat treatment can be performed under reduced pressure, or a polymerization catalyst can be mixed into the polymer liquid crystal. Similar effects can also be obtained by applying the polymer in a molten state on an oriented substrate and then performing a heat treatment.

The alignment state thus obtained is then cooled to a temperature lower than the glass transition point of the polymer liquid crystal, whereby the alignment can be fixed without impairing the alignment at all. Generally, when a polymer having a crystal phase in a lower temperature portion than a liquid crystal phase is used, the orientation in the liquid crystal state is broken by cooling. According to the method of the present invention, since a polymer system having a glass phase below a liquid crystal phase is used, such a phenomenon does not occur, and the orientation of the polymer liquid crystal can be completely fixed. There is no particular limitation on the cooling rate, and the cooling rate is fixed only by taking out from the heating atmosphere into an atmosphere below the glass transition point. In order to increase production efficiency, forced cooling such as air cooling or water cooling may be performed.

In the method for producing a heat-resistant optical element using the liquid crystalline polymer of the present invention, the heat treatment for imparting heat resistance may be performed separately from the heat treatment for aligning the polymer liquid crystal. May be performed plural times.
That is, a plurality of heat treatment tanks are prepared, the polymer liquid crystal is oriented first, then the heat resistance is imparted in a high-temperature bath, or after the polymer liquid crystal is oriented, the sample is cooled once, and the polymer liquid crystal is cooled. The same effect can be obtained by performing a heat treatment for imparting heat resistance after fixing the orientation of. In such a case, it is preferable that the heat treatment temperature is high in order to assist the alignment by the interfacial effect at the time of the alignment treatment. Accordingly, the heat treatment is preferably performed at a temperature equal to or higher than the glass transition point and equal to or lower than the transition point to the isotropic phase.
A range of 00 ° C. is preferred, and a range of 100 ° C. to 250 ° C. is particularly preferred. The time required to obtain sufficient alignment in the liquid crystal state on the alignment film depends on the composition and molecular weight of the polymer and cannot be unconditionally determined, but is preferably in the range of 10 seconds to 60 minutes, and particularly preferably in the range of 30 seconds to 30 minutes. A range is preferred. If the time is shorter than 10 seconds, the orientation becomes insufficient, and if the time is longer than 60 minutes, the productivity is undesirably reduced. A similar orientation state can also be obtained by applying a polymer in a molten state on an oriented substrate and then performing a heat treatment.

By subjecting the thus-obtained oriented sample to a heat treatment at a temperature at which thermal polymerization of the polymer liquid crystal proceeds, heat resistance can be imparted without impairing the orientation state of the sample. The heat treatment for imparting heat resistance may be performed subsequently to the heat treatment for the alignment treatment, or the sample that has been subjected to the heat treatment for the alignment treatment is once cooled to a temperature equal to or lower than the glass transition point of the polymer liquid crystal. May be performed after the orientation is fixed. It is preferable that the heat treatment temperature is high in order to promote thermal polymerization. However, if the temperature is too high, depending on the type of polymer, an isotropic phase is formed in a high-temperature portion. Therefore, according to the characteristics of the polymer used, it is preferable to perform the heat treatment at a temperature lower than the transition point to the isotropic phase and at a temperature at which the polymerization of the high-molecular liquid crystal proceeds, generally in the range of 100 ° C. to 350. At 150 ° C
The range of -300 ° C is preferred. The time required for imparting sufficient heat resistance depends on the composition, molecular weight and required heat resistance of the polymer and cannot be unconditionally determined, but is preferably in the range of 10 seconds to 60 minutes, and particularly preferably in the range of 30 seconds. A range of 30 minutes is preferred. When the time is shorter than 10 seconds, sufficient heat resistance is not provided, and when the time is longer than 60 minutes, productivity is undesirably reduced. In order to provide sufficient heat resistance in a short heat treatment time, heat treatment can be performed under reduced pressure, or a polymerization catalyst can be mixed into the polymer liquid crystal.

The alignment sample thus obtained is then cooled to a temperature lower than the glass transition point of the polymer liquid crystal, whereby the alignment can be fixed without impairing the alignment at all. Generally, when a polymer having a crystal phase in a lower temperature portion than a liquid crystal phase is used, the orientation in the liquid crystal state is broken by cooling. According to the method of the present invention, since a polymer system having a glass phase below a liquid crystal phase is used, such a phenomenon does not occur, and the orientation of the polymer liquid crystal can be completely fixed. There is no particular limitation on the cooling rate, and the cooling rate is fixed only by taking out from the heating atmosphere into an atmosphere below the glass transition point. In order to increase production efficiency, forced cooling such as air cooling or water cooling may be performed.

The optical element of the present invention manufactured as described above has high heat resistance while maintaining the characteristics of the optical element using a liquid crystalline polymer.
The degree of freedom in the subsequent processing and incorporation into equipment is expanded, and it is extremely useful in the field of optics or optoelectronics. In particular, in the field of displays, it contributes to improvement of contrast and brightness of an in-vehicle liquid crystal display device and a projection type liquid crystal display device. Further, the optical element of the present invention has such features that the restriction on the maximum temperature of the manufacturing process is eased when incorporated into an optical device or a display device, and is extremely industrially valuable.

[0033]

EXAMPLES Examples will be described below, but the present invention is not limited to these examples. In addition, each analysis method used in the Example is as follows. (1) Determination of composition of polymer The polymer was dissolved in deuterated chloroform or deuterated trifluoroacetic acid, and measured and determined by 400 MHz ¹ H-NMR (JNM-GX400 manufactured by JEOL Ltd.).

(2) Measurement of logarithmic viscosity The viscosity was measured at 30 ° C. in a phenol / tetrachloroethane (60/40 weight ratio) mixed solvent using an Ubbelohde viscometer.

(3) Determination of liquid crystal phase series DSC (DuPont 990 Thermal An)
aliza) measurement and observation with an optical microscope (BH2 polarizing microscope manufactured by Olympus Optical Co., Ltd.).

(4) Determination of Twist Angle and Δn · d The twist angle was determined by ellipsometry, and Δn · d was determined by analyzing data measured with an ellipsometer.

Embodiment 1

Embedded image 18% by weight of phenol / tetrachloroethane (60/50) containing the polymer represented by the formula (1) (logarithmic viscosity: 0.13)
(40 weight ratio) solution was prepared. Using this solution, 15
On a glass plate having a rubbed polyimide layer having a size of cm × 23 cm and a thickness of 0.1 cm, it was cast using a screen printing machine, dried, and then dried at 280 ° C. × 6.
Heat treatment was performed for 0 minutes, and then cooling was performed to fix a uniform monodomain nematic structure. Δn · of this optical element
d is 0.92 μm and the logarithmic viscosity of the polymer is 2.2
Was rising. A silicone-based hard coat material was applied to the polymer liquid crystal surface of the optical element thus produced by a spray coating method, and after setting, heat treatment was performed at 120 ° C. for 60 minutes to cure the hard coat material. Even after the heat treatment for hardening the hard coat material, the optical element had a uniform monodomain nematic structure, and no change in optical parameters was observed.

Example 2 18% by weight of phenol / tetrachloroethane (60/50%) containing the polymer represented by the formula (1) (logarithmic viscosity: 0.13)
(40 weight ratio) solution was prepared. Using this solution, 15
On a glass plate having a rubbed polyimide layer having a size of cm × 23 cm and a thickness of 0.1 μm, it was cast using a screen printing machine, dried, and then dried at 180 ° C. × 3.
0 minute heat treatment, then cooling to fix the uniform monodomain nematic structure,
Heat treatment was performed at 90 ° C. for 45 minutes. Δ of this optical element
n · d was 0.93 μm, and the logarithmic viscosity of the polymer was increased to 2.8. The optical element thus produced was subjected to thermocompression bonding with another glass sheet at 140 ° C. × 14 kgf / cm ² for 20 minutes using a polyvinyl butyral sheet as an intermediate layer. The obtained laminated glass had high transparency and no change in optical parameters was observed.

Embodiment 3

Embedded image The mixed polymer represented by the formula (2) (logarithmic viscosity of base polymer 0.18, logarithmic viscosity of optically active polymer 0.15)
A phenol / tetrachloroethane (60/40 weight ratio) solution containing 15% by weight was prepared. Using this solution, a film was formed using a roll coater on a 50 μm-thick polyethersulfone film having a rubbed polyimide layer having a size of 15 cm × 23 cm, and then dried, followed by heat treatment at 180 ° C. for 30 minutes. And then cooled to fix the uniform monodomain twisted nematic structure and then again under reduced pressure (0.05 mmHg)
At 190 ° C. for 60 minutes. The twist angle of this optical element is -230 ° and Δn · d is 0.84 μ
m. The logarithmic viscosity of the polymer was increased to 1.6. A silicone-based hard coat material was applied to the polymer liquid crystal surface of the optical element thus manufactured by a spray coating method, set, and then heat-treated at 120 ° C. for 60 minutes to cure the hard coat material. Even after the heat treatment for hardening the hard coat material, the sample retained a uniform monodomain twisted nematic structure, and no change in optical parameters was observed.

Comparative Example 1 18% by weight of phenol / tetrachloroethane (60/60%) containing the polymer represented by the formula (1) (logarithmic viscosity: 0.13)
(40 weight ratio) solution was prepared. Using this solution, 15
On a glass plate having a rubbed polyimide layer having a size of cm × 23 cm and a thickness of 0.1 cm, the film was cast using a screen printing machine and then dried, and then dried at 180 ° C. × 3.
A heat treatment was performed for 0 minutes, and then the mixture was cooled to fix the nematic structure. Δn · d of this optical element was 0.94 μm, and the logarithmic viscosity of the polymer hardly changed. A silicone-based hard coat material was applied to the polymer liquid crystal surface of the optical element thus manufactured by a spray coating method, set, and then heat-treated at 120 ° C. for 60 minutes to cure the hard coat material. After the heat treatment for hardening the hard coat material, the orientation of the polymer liquid crystal layer was disturbed, and the monodomain structure was not maintained.

Comparative Example 2 18% by weight of phenol / tetrachloroethane (60/60%) containing the polymer represented by the formula (1) (logarithmic viscosity: 0.13)
(40 weight ratio) solution was prepared. Using this solution, 15
On a glass plate having a rubbed polyimide layer having a size of cm × 23 cm and a thickness of 0.1 cm, the film was cast using a screen printing machine and then dried, and then dried at 180 ° C. × 3.
Heat treatment was performed for 0 minutes, and then cooling was performed to fix a uniform monodomain nematic structure. Δn · of this optical element
d was 0.94 μm, and the logarithmic viscosity of the polymer hardly changed. The optical element thus produced was subjected to thermocompression bonding with another glass sheet at 140 ° C. × 14 kgf / cm ² for 20 minutes using a polyvinyl butyral sheet as an intermediate layer. The resulting laminated glass was opaque and the uniform monodomain nematic structure was completely destroyed.

Comparative Example 3 Mixed polymer represented by formula (2) (logarithmic viscosity of base polymer: 0.18, logarithmic viscosity of optically active polymer: 0.15)
A phenol / tetrachloroethane (60/40 weight ratio) solution containing 15% by weight was prepared. Using this solution, a film was formed using a roll coater on a 50 μm-thick polyethersulfone film having a rubbed polyimide layer having a size of 15 cm × 23 cm, and then dried, followed by heat treatment at 180 ° C. for 30 minutes. This was followed by cooling to immobilize a uniform monodomain twisted nematic structure. The twist angle of this optical element is -225 °,
Δn · d was 0.84 μm. Also, the logarithmic viscosity of the polymer hardly changed. A silicone-based hard coat material was applied to the polymer liquid crystal surface of the optical element thus manufactured by a spray coating method, and after setting, a heat treatment was performed at 120 ° C. for 60 minutes to cure the hard coat material. After the heat treatment for hard coating material hardening, the sample did not retain a uniform monodomain twisted nematic structure.

[0043]

According to the method for producing a heat-resistant optical element using a liquid crystalline polymer of the present invention, high heat resistance can be imparted while maintaining the characteristics of an optical element using a liquid crystalline polymer.
The degree of freedom in the use environment, secondary processing, and incorporation into equipment of the optical element produced by this method is widened, and the industrial value is extremely high in fields such as optics and optoelectronics.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G02F 1/13363 G02F 1/1335 G02F 1/13 101 G02F 1/13 505

Claims (1)

(57) [Claims] An alignment film is formed on a light-transmitting substrate to form a liquid crystal.
And nematic orientation or a twisted nematic orientation in state, there in the liquid crystal polymer ing and glassy state below the liquid crystal transition point
Liquid crystalline polymer that has the property of polymerizing further by heat
In the method for manufacturing an optical element by coating on the orientation film to form a layer made of the polymer, the alignment treatment of the polymer layer and / or after orientation fixed polymerization of the polymer is heat-treated at a temperature to proceed A method for producing a heat-resistant optical element, comprising: