JP3213761B2 - 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. Further, it is also possible to manufacture optical elements on various substrates by aligning the polymer liquid crystal layer on an alignment substrate, fixing the polymer liquid crystal layer, and then transferring the polymer liquid crystal layer onto a light-transmitting substrate.

The present inventors have heretofore described, as an optical element using a liquid crystalline polymer, a compensating plate for a liquid crystal display element having a twisted structure inside a film (JP-A-3-87720) and an optical rotatory optical element (Japanese Patent Application No. Hei. 2-126962). These optical elements have high performance that could not be achieved with conventional optical elements, and those fabricated on polymer films have properties unique to polymer films such as light, thin, and flexible. It was a revolutionary combination. 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.

[0004]

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. In other words, if a heat treatment is performed during the alignment treatment of the liquid crystalline polymer, after the alignment is fixed, or after the transfer, the liquid crystalline polymer is aligned, and the flowability of the liquid crystal polymer is reduced while maintaining the alignment structure, and the heat resistance of the optical element is reduced. And finally completed the present invention.

[0005]

That is, the present invention provides a liquid crystal state in which nematic alignment or twisted nematic alignment is performed,
Liquid-crystalline polymer der ing and glassy state below the liquid crystal transition point
Liquid crystalline polymer having the property of being further polymerized by heat
Is coated on an alignment substrate to form a layer composed of the polymer,
Then the optical element produced by transferring the polymer layer on a transparent substrate, at least during the alignment process the polymer layer,
The present invention relates to a method for manufacturing a heat-resistant optical element, wherein a heat treatment is performed at a temperature at which polymerization of a liquid crystalline polymer proceeds in one stage after alignment fixation and transfer. The method for producing a heat-resistant optical element using the liquid crystalline polymer of the present invention has a high fluidity during the alignment treatment, and the liquid crystal polymer is used in a state of high alignment. Heat resistance can be imparted.

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 / or crosslinking by heat. There are two types of polymer liquid crystals that undergo twisted nematic alignment: a polymer that has an optically active group itself and a polymer that exhibits twisted nematic liquid crystallinity in a mixture of a base polymer that does not have an optically active group and another optically active compound.

As the polymer to be used, any thermopolymerizable high-molecular liquid crystal which is in a nematic alignment or 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 a twisted nematic alignment, optically active polyester, polyamide, main chain type liquid crystal polymer such as polyester imide, or non-optically active polyester,
Examples thereof include polymers obtained by adding other low-molecular or high-molecular optically active compounds to a main-chain liquid crystal polymer such as polyamide or polyesterimide. 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.

As an example of these,

(X represents hydrogen, 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.

[0009]

(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.

[0011]

(Y represents hydrogen, halogen such as Cl, Br, etc., an alkyl group having 1 to 4 carbon atoms, or an alkoxy or phenyl group. L is 0 to 2.)

(N represents an integer of 2 to 12)

Embedded image

And the like are preferably used.

The following can be exemplified as the dicarboxylic acid component.

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

Embedded image

And the like.

The following units can be specifically exemplified as the oxycarboxylic acid component.

The molar ratio of the dicarboxylic acid to the diol is approximately 1: 1 as in the case of a 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. Also 40
If it is more than mol%, the polymer tends not to exhibit liquid crystallinity, which is not preferable. The following polymers can be exemplified as typical polyesters.

[0014]

A polymer composed of the structural units of the formula:

A polymer comprising a structural unit of the following formula:

A polymer composed of structural units of the formula:

A polymer composed of structural units of the formula:

A polymer composed of structural units of the formula:

A polymer composed of structural units of the formula:

A polymer composed of structural units of the formula:

A polymer comprising the structural unit of the formula:

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

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The molecular weight of these polymers can be determined in various solvents such as phenol / tetrachloroethane (60/40
(Weight ratio) The logarithmic viscosity measured at 30 ° C in the mixed solvent is usually preferably from 0.05 to 3.0, more preferably from 0.07 to 2.0. Logarithmic viscosity is 0.05
If it is smaller, 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 a melt polymerization method, for example, an acetylated product of the corresponding dicarboxylic acid and the corresponding diol can be produced by polymerizing under a high temperature and a high vacuum, and the molecular weight can be easily controlled by controlling the polymerization time or controlling the charged composition. .
In order to accelerate the polymerization reaction, a conventionally known metal salt such as sodium acetate can be used. Also acid
When the chloride method is used, the 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.

[0019]

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.

[0021]

A polymer composed of structural units of the formula:

A polymer composed of structural units of the formula:

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

A polymer composed of structural units of the formula:

A polymer composed of structural units of the formula:

A polymer composed of structural units of the formula:

A polymer composed of structural units of the formula:

A polymer composed of structural units of the formula:

A polymer composed of structural units of the formula:

A polymer composed of structural units of the formula:

A polymer comprising the structural unit of the formula:

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 which can form a uniform and monodomain twisted nematic alignment by itself without using other optically active compounds and can easily fix 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)

[0024]

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And the like.

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,

(M / n = usually 99.
9 / 0.1-80 / 20, preferably 99.5 / 0.5
~ 90/10, more preferably 99/1 ~ 95/5)

A polymer represented by the following formula (m / n = 0.5 / 9)
9.5 to 10/90, preferably 1/99 to 5/95)

A polymer represented by the following formula (m / n = 0.5 / 9)
9.5 to 10/90, preferably 1/99 to 5/95)

A polymer represented by the following formula (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)

A polymer represented by the following formula (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)

A polymer mixture represented by the following formula ((A) / (B))
= Usually 99.9 / 0.1-80 / 20 (weight ratio), preferably 99.5 / 0.5-85 / 5, more preferably 99 / 1-95 / 5, K = 1 + m, l / m = 75/25
~ 25/75, P = q + r, p / q = 80/20 ~ 20
/ 80) (A)

(B) Polymer mixture represented by cholesteryl benzoate ((A) / (B) = normally 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)

A polymer mixture represented by the following formula ((A) / (B))
= Usually 99.9 / 0.1-70 / 30 (weight ratio), preferably 99.5 / 0.5-80 / 20, preferably 99
/ 1 to 90/10, K = l + m, l / m = 25/75-
75/25, P = q + r, p / r = 20 / 80-80 /
20) (* indicates optically active carbon).

The method for producing a heat-resistant optical element comprising a liquid crystalline polymer according to the present invention is basically an optical element produced by transferring a liquid crystalline polymer layer formed on an alignment substrate onto a light transmitting substrate. In the method, the liquid crystal polymer layer is subjected to a heat treatment at a temperature at which polymerization of the liquid crystal polymer proceeds at least in one stage after the alignment treatment, after the alignment is fixed, and after the transfer.
The alignment substrate used in the production of the optical element of the present invention may be any one that has a capability of aligning a polymer liquid crystal, a predetermined heat resistance, a solvent resistance, and a peeling property capable of peeling a polymer liquid crystal layer. All can be used. Alignment ability, required heat resistance, solvent resistance or releasability, can not be said unconditionally because it depends on the type and properties of the polymer liquid crystal used,
Representative examples include a rubbed polyimide film and a rubbed polyvinyl alcohol film formed on a sheet-like or plate-like substrate such as a metal plate of aluminum, iron, or copper, a ceramic plate, an enamel plate, or glass. Alternatively, an oblique deposition film of silicon oxide or the like can be given. Other examples include polyimide, polyamide imide, polyether imide, polyamide, polyether ether ketone, polyether ketone, polyketone sulfide, polyether sulfone, polysulfone, polyphenylene sulfide, polyphenylene oxide, polyethylene terephthalate, polybutylene terephthalate, and polyacetal. , Polycarbonate, acrylic resin, polyvinyl alcohol, cellulosic plastics, epoxy resin,
Examples of the substrate include a plastic film such as a phenol resin or a substrate itself obtained by directly rubbing the surface of a sheet. Alternatively, a rubbed polyimide film, a rubbed polyvinyl alcohol film, and the like formed on these films or sheets are also examples of the alignment film. Among these plastic films or sheets, those with high crystallinity have the ability to align the polymer liquid crystal only by uniaxial stretching. For those, it is necessary to directly apply a rubbing treatment or a rubbing polyimide alignment film. It can be used as an alignment film as it is without performing. Examples include polyimide, polyether imide, polyether ether ketone, polyether ketone, polyphenylene sulfide, polyethylene terephthalate, and the like.

From the viewpoint of workability in the transfer step, an alignment film having high flexibility is more preferable. Among these, polyimide, polyethylene terephthalate, polyphenylene sulfide, polyether ether ketone, polyether ketone, polyether imide, polyvinyl alcohol An alignment film obtained by directly rubbing the above film or sheet is particularly preferable. A polymer liquid crystal is coated on these alignment films, dried and heat-treated to form a uniform, monodomain nematic structure or twisted nematic structure. Then, the optical element of the present invention is manufactured by immobilizing the alignment in the liquid crystal state without impairing it, and transferring it onto a light-transmitting substrate.

First, a nematic liquid crystalline or twisted nematic liquid crystalline 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, and halogenated carbonization such as chloroform, dichloroethane, tetrachloroethane, trichloroethylene, tetrachloroethylene and orthodichlorobenzene. Hydrogen, a mixed solvent thereof with phenol, dimethylformamide, dimethylacetamide, dimethylsulfoxide 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 an alignment substrate.

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 the heat treatment for orientation and the heat treatment for thermal polymerization are performed at the same time, the heat treatment temperature is preferably higher in order to assist the orientation by the interface effect and to promote the thermal polymerization. In comparison, it is preferable that the heat treatment temperature is higher. However, if the temperature is too high, depending on the type of the polymer, the polymer has an isotropic phase in a high-temperature portion. That is, according to the characteristics of the polymer, 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, and at a temperature at which the polymerization of the high-molecular liquid crystal proceeds. Is preferable,
Particularly, the range of 150 ° C. to 300 ° C. is preferable. 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 are:
Although it depends on the composition, molecular weight and required heat resistance of the polymer and cannot be unconditionally determined, it is preferably in the range of 30 seconds to 120 minutes, particularly preferably in the range of 60 seconds to 100 minutes. When the time is shorter than 30 seconds, the orientation becomes insufficient and 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.
In other words, preparing a plurality of heat treatment tanks having different temperatures, first aligning the polymer liquid crystal, then imparting heat resistance in a high-temperature tank, orienting the polymer liquid crystal, and then cooling the sample once, A similar effect can be obtained by performing a heat treatment for imparting heat resistance after fixing the orientation of the polymer liquid crystal. In addition, the same effect can be obtained by performing a heat treatment for imparting heat resistance after transferring the polymer liquid crystal layer onto the translucent substrate without performing a heat treatment for imparting heat resistance on the alignment substrate. Can be. 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, but if the temperature is too high, depending on the type of the polymer, the polymer has an isotropic phase in a high-temperature portion. Accordingly, it is preferable to perform the heat treatment 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, generally in the range of 50 ° C to 300 ° C, and particularly preferably in the range of 100 ° C to 250 ° C. is there. 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 the 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. In general, the heat treatment conditions at this time are preferably in the range of 100 ° C. to 350 ° C.
In particular, the range of 150 ° C to 300 ° C is suitable, and generally,
It is desirable that the temperature is higher than the heat treatment temperature only for the alignment treatment, but if the temperature is too high, depending on the type of the polymer, the polymer has an isotropic phase in a high temperature part. As a result, according to the characteristics of the used liquid crystalline polymer (polymer), it is desirable 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 polymer liquid crystal proceeds. The time required for imparting sufficient heat resistance depends on the composition, molecular weight and required heat resistance of the polymer and cannot be determined unconditionally, but is preferably in the range of 10 seconds to 60 minutes, particularly preferably 30 minutes.
A range from seconds to 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. Further, the heat treatment for imparting heat resistance may be performed after transferring the polymer liquid crystal layer onto the translucent substrate without performing the heat treatment for imparting heat resistance on the alignment substrate (described later).

As described above, a film having a layer of the optical element of the present invention on an alignment substrate is obtained. Next, a method of transfer onto another translucent substrate will be described. First, the surface of the polymer liquid crystal layer of this film and another translucent substrate are bonded together using an adhesive or a pressure-sensitive adhesive. Next, the polymer liquid crystal layer is peeled off at the interface between the alignment substrate and the polymer liquid crystal layer, and only the polymer liquid crystal layer is transferred onto another translucent substrate. Examples of the translucent substrate to be used include, besides various types of glass, plastic films having transparency and optical isotropy.
For example, polymethyl methacrylate, polystyrene, polycarbonate, polyether sulfone, polyphenylene sulfide, polyarylate, polyethylene terephthalate, amorphous polyolefin, triacetyl cellulose, epoxy resin, or the like can be used. Among them, polymethyl methacrylate, polycarbonate, polyether sulfone, polyarylate, triacetyl cellulose, amorphous polyolefin, polarizing film and the like are preferably used. Further, it is also possible to transfer these substrates to the substrate portion of an apparatus or device having a part of the member.

The adhesive or pressure-sensitive adhesive for adhering the translucent substrate and the polymer liquid crystal layer is not particularly limited as long as it is of an optical grade, but may be acrylic, epoxy, ethylene-vinyl acetate copolymer or rubber. Etc. can be used. The peeling method may of course be a manual operation, and more complete transfer is possible by mechanical means. Since the releasability differs depending on the properties of the polymer liquid crystal and the alignment substrate to be used, the method most suitable for the system should be adopted. Further, as described above, it is also possible to perform a heat treatment for imparting heat resistance after transferring the polymer liquid crystal layer onto the translucent substrate. In this case, the heat treatment temperature is preferably higher to promote the thermal polymerization of the polymer liquid crystal layer, but the heat treatment temperature is preferably higher to promote the thermal polymerization, but if the temperature is too high, depending on the type of the polymer, Since it has an isotropic phase in the high-temperature portion, the orientation state is not maintained when heat treatment is performed in this temperature range. 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 ° C. Preferred, especially 150
A range of from 300C to 300C 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 under reduced pressure,
It is also possible to mix a polymerization catalyst in the polymer liquid crystal.

The alignment sample thus obtained is then cooled to a temperature lower than the glass transition point of the liquid crystal polymer, 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 limitation on the maximum temperature of the manufacturing process is eased when the optical element is incorporated into an optical device or a display device, and is extremely high in industrial value.

[0038]

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 Torsion Angle and Δn · d The torsion angle was determined by ellipsometry, and Δn · d was determined by analyzing data measured with an ellipsometer.

Example 1

Embedded image The polymer represented by the formula (1) (logarithmic viscosity: 0.1
A 17% by weight phenol / tetrachloroethane (60/40 weight ratio) solution containing 8) was prepared. Using this solution, a directly rubbed polyetheretherketone having a size of 15 cm × 23 cm and a thickness of 100 μm (P
EEK) A film was formed on a film using a gravure roll coater, dried, heat-treated at 270 ° C. for 60 minutes, and then cooled to fix a uniform monodomain nematic structure. Using a UV-curable acrylic adhesive on this polymer liquid crystal layer, the same size 50 μm thick
Polyethersulfone (PES) film was attached and adhered. Next, the PEEK film used as the alignment substrate was gently peeled off, and the polymer liquid crystal layer was transferred onto the PES film. Δn · d of this optical element was 0.82 μm, and the logarithmic viscosity of the polymer was increased to 1.9. 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 optical element had a uniform monodomain nematic structure, and no change in optical parameters was observed.

Example 2 17% by weight of phenol / tetrachloroethane (60/60%) containing the polymer represented by the formula (1) (logarithmic viscosity: 0.18)
(40 weight ratio) solution was prepared. Using this solution, 15
A gravure roll coater was used to form a coating film on a directly rubbed polyimide (PI) film having a size of cm × 23 cm and a thickness of 75 μm, followed by drying.
A heat treatment was performed at 0 ° C. for 30 minutes, and then, after cooling to fix a uniform monodomain nematic structure, another heat treatment was performed at 290 ° C. for 45 minutes. This polymer liquid crystal layer is adhered on glass using an epoxy-based adhesive,
Next, gently peel off the PI film used as the alignment substrate,
The polymer liquid crystal layer was transferred onto glass. Δ of this optical element
n · d was 0.80 μm, and the logarithmic viscosity of the polymer was increased to 2.9. 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

(2) A 15 wt% phenol / tetrachloroethane (60/40 weight ratio) solution containing the mixed polymer represented by the formula (logarithmic viscosity of base polymer 0.18, logarithmic viscosity of optically active polymer 0.15) Was prepared. Using this solution, a film was formed on a 50 μm-thick PEEK film directly rubbed with a size of 15 cm × 23 cm using a roll coater, and then dried, and dried at 180 ° C. × 3.
A heat treatment was performed for 0 minutes, followed by cooling to fix a uniform monodomain twisted nematic structure. This polymer liquid crystal layer is made of polyarylate (PA) using an epoxy adhesive.
PEE adhered on film and then used as alignment substrate
The K film was gently peeled off, and the polymer liquid crystal layer was transferred onto the PA film. Next, the transferred film was heat-treated at 190 ° C. for 60 minutes under reduced pressure (0.05 mmHg). The twist angle of this optical element is -230 °,
Δn · d was 0.84 μm. 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, and after setting,
Heat treatment was performed at 20 ° C. for 60 minutes to harden 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 17% by weight of phenol / tetrachloroethane (60/60%) containing the polymer represented by the formula (1) (logarithmic viscosity: 0.18)
(40 weight ratio) solution was prepared. Using this solution, 15
A gravure roll coater was used to form a coating film on a directly rubbed polyetheretherketone (PEEK) film having a size of cm × 23 cm and a thickness of 100 μm, followed by drying and heat treatment at 180 ° C. for 60 minutes.
Next, it was cooled to immobilize a uniform monodomain nematic structure. A 50 μm-thick polyethersulfone (PES) film of the same size was adhered to and bonded to the polymer liquid crystal layer using a UV-curable acrylic adhesive. Next, the PEEK film used as the alignment substrate was gently peeled off, and the polymer liquid crystal layer was transferred onto the PES film.
Δn · d of this optical element was 0.84 μm, and the logarithmic viscosity of the polymer was 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 17% by weight of phenol / tetrachloroethane (60/60) containing the polymer represented by the formula (1) (logarithmic viscosity: 0.18)
(40 weight ratio) solution was prepared. Using this solution, 15
A gravure roll coater was used to form a coating film on a directly rubbed polyimide (PI) film having a size of cm × 23 cm and a thickness of 75 μm, followed by drying.
Heat treatment was performed at 0 ° C. for 30 minutes, and then cooling was performed to fix a uniform monodomain nematic structure. This polymer liquid crystal layer was adhered on glass using an epoxy adhesive, and then the PI film used as an alignment substrate was gently peeled off, and the polymer liquid crystal layer was transferred onto glass. Δn of this optical element
D was 0.80 μm, and the logarithmic viscosity of the polymer was 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 is opaque,
The nematic structure of the homogeneous monodomain 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 on a 50 μm-thick PEEK film directly rubbed in a size of 15 cm × 23 cm using a roll coater, dried, heat-treated at 180 ° C. for 30 minutes, and then cooled. To immobilize a uniform monodomain twisted nematic structure. This polymer liquid crystal layer was adhered on a polyarylate (PA) film using an epoxy adhesive, and then the PEEK film used as an alignment substrate was gently peeled off, and the polymer liquid crystal layer was transferred onto the PA film. The twist angle of this optical element is -225 °, Δ
n · d was 0.85 μm. The logarithmic viscosity of the polymer was 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.

[0048]

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] 1. A to nematic orientation or a twisted nematic orientation in a liquid crystal state, it a glassy state below the liquid crystal transition point
The property of further polymerized by a liquid-crystalline polymer heat that
Having a liquid crystalline polymer on an alignment substrate
Forming a Li Cheng layer, then the optical element produced by transferring the polymer layer on a transparent substrate, at least during the alignment process the polymer layer, the liquid crystal in one stage and after post-transcriptional orientation fixed A method for producing a heat-resistant optical element, comprising performing heat treatment at a temperature at which polymerization of a conductive polymer proceeds.