JP2002055229A - Molecular alignment optical component and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molecular alignment optical component especially a polarizing plate which is light in weight (1), is capable of being molded into a large area part with several μm to several cm thickness (2), is usable with a light beam between a visible ray region and an infrared ray region (3), has a wide selection width of optical performance and further is easily controllable (4), is excellent in heat resistance and weather resistance (5), withstands a long period of use and thermal stress (6) and has excellent productivity (7). SOLUTION: The molecular alignment optical part is characterized by making light with a specified direction irradiate a mixture of a cyano group containing (meth)acrylate monomer or oligomer with a photo setting monomer and by hardening the mixture.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic molecular orientation optical component which is lightweight, has excellent heat resistance and weather resistance, and is particularly suitable for use as a polarizing plate for a liquid crystal panel or the like.

[0002]

2. Description of the Related Art Hitherto, as a polarizing plate, which is a kind of molecular orientation optical component, a polarizing plate in which an inorganic compound or an organic compound is oriented in a certain direction in glass or plastic to impart a polarizing property has been proposed. As a polarizing glass in which a specific compound is oriented in glass, an infrared polarizing glass in which a silver salt is precipitated and oriented in a glass stretching direction is commercially available,
By controlling the size of the silver salt particles, high-performance polarization performance with an extinction ratio of 1: 1000 to 10,000 is obtained. However, the polarizing glass has problems that it is heavy, it is difficult to reduce the thickness and the area, and the usable wavelength range is not the visible light range.

On the other hand, as a film in which a specific compound is oriented in plastic, a polarizing film in which a stretched film of polyvinyl alcohol or the like is doped with iodine or a dichroic dye and oriented is commercially available. It has a polarization degree of 90% or more. Although the polarizing film can solve the above-mentioned problems of the polarizing glass, there is a problem that heat resistance and weather resistance are inferior. Further, in order to achieve a low price, development of a polarizing film having better productivity and excellent polarizing performance is desired. Further, Japanese Unexamined Patent Publication No.
JP-A-159819 describes a plastic polarizing plate in which a cyano group-containing compound is physically dissolved. However, this polarizing plate can be used for a long period of time to remove the free cyano group-containing compound or to reduce the heat of orientation. It has been clarified that the degree of polarization may decrease due to thermal relaxation or the like.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and is lightweight and can be molded in a thickness of several μm to several cm even in a large area, and can be used for light rays in the visible or infrared region. To provide molecular orientation optical components, especially polarizers, which have a wide range of selectable optical performances, are easy to control, have excellent heat resistance and weather resistance, are resistant to long-term use and thermal stress, and are excellent in productivity. It is intended for.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above problems, and as a result, have found that a mixture of a cyano group-containing (meth) acrylate monomer or oligomer and a photocurable monomer. In addition, by irradiating light in a certain direction, the monomer or oligomer containing a cyano group in the polymer is arranged in a certain direction upon curing, and at the same time chemically bonds with the matrix resin by itself,
The present invention has been found to produce an optical component having a molecular orientation which is resistant to long-term and thermal stress. That is, the present invention is characterized in that a mixture of a (meth) acrylate-based monomer or oligomer containing a cyano group and a photocurable monomer is irradiated with light in a certain direction to cure the mixture. The present invention relates to a molecular orientation optical component and a method for manufacturing the same.

In the present invention, the optical component means a liquid crystal panel member such as a polarizing plate, an optical communication isolator, and the like. The sheet-like body means all the molded products having a flat front surface, and the thickness of the sheet is not limited. Therefore, the concept generally includes what is called a film, a sheet, and a block. (Meth) acrylate is a general term for acrylate and methacrylate.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The photocurable monomer used in the present invention is not particularly limited as long as it can be polymerized and cured by irradiation with light to form a transparent polymer. Preferably a (meth) acrylate compound, particularly preferably a bifunctional or higher polyfunctional (meth) compound
An acrylate compound, most preferably a bifunctional or higher polyfunctional acrylate. As the (meth) acrylate-based compound, triethylene glycol di (meth) acrylate, hexanediol di (meth) acrylate,
2,2-bis [4- (meth) acryloyloxyphenyl] propane, 2,2-bis [4- (2- (meth) acryloyloxyethoxy) phenylpropane, bis (oxymethyl) tricyclo [5.2.1 0.0 ^2,6 ] decane dimethacrylate, p-bis [β- (meth) acryloyloxyethylthio] xylylene, 4,4′-bis [β- (meth) acryloyloxyethylthio] diphenylsulfone, trimethylolpropane Polyfunctional (meth) acrylates such as tri (meth) acrylate, urethane acrylate, epoxy acrylate, and mixtures of these monomers with copolymerizable monofunctional monomers,
In addition, a mixture of these polyfunctional (meth) acrylate compounds and polythiol capable of addition polymerization can be used. Monofunctional monomers include, for example, methyl (meth) acrylate and benzyl (meth) acrylate, and polythiols include, for example, pentaerythritol tetrakis (β-thiopropionate) and tris [2- (β-thiopropionyloxy) ethyl] tri And isocyanurate.

In order to cure these photocurable monomers by light irradiation, a photopolymerization initiator is added to the photocurable monomers. Known photopolymerization initiators are used, for example, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, trimethylbenzoylphenylphosphinic acid methyl ester, 1-hydroxycyclohexylphenyl ketone, benzophenone, diphenoxybenzophenone, and the like. No. These photopolymerization initiators may be used alone or in combination of two or more. In addition, the photocurable monomer, if necessary, an antioxidant,
Curing can also be performed by adding additives such as an ultraviolet absorber and a coloring agent.

As the (meth) acrylate monomer or oligomer having a cyano group (hereinafter sometimes abbreviated as “cyano group-containing compound”), a monomer or oligomer having a cyano group and a (meth) acrylate group is used. Generally, the number of carbon atoms to which a cyano group is bonded is 1 to 10
A monomer comprising an ester of acrylic acid or methacrylic acid with 0, preferably about 2 to 20 hydrocarbon groups (the hydrocarbon group may contain elements other than carbon and hydrogen, such as O, S, N, etc.) Alternatively, an oligomer composed of a monomer is suitably used. When the hydrocarbon group has a ring structure,
The ring structure may include a hetero atom such as N, O, S, and the like. The number of cyano groups in one monomer molecule is not particularly limited as long as it is one or more. The number of (meth) acrylate groups in one monomer molecule may be one or more. These cyano group-containing compounds may be used alone or as a mixture of a plurality of types.

Specific examples of the monomer constituting the (meth) acrylate monomer having a cyano group and the (meth) acrylate oligomer having a cyano group include 2-cyanoethyl acrylate (H ₂ C ＝ CHCO ₂ )
_{2 CH 2 CH 2 CN),} 2- cyanoethyl methacrylate _{(H 2 C = C (CH} 3) CO 2 CH 2 CH 2 CN),
Cyanomethyl methacrylate (H ₂ C = C (CH ₃ ) C
O ₂ CH ₂ CN), 1-cyano-1-methylethyl methacrylate (H ₂ C ＝ C (CH ₃ ) CO ₂ C (CH ₃ )
₂ CN), cyanobenzyl methacrylate (H ₂ C = C
_{(CH 3) CO 2 CH (} C 6 H 5) CN), 1- cyanomethyl-2-cyanoethyl methacrylate (H ₂ C = C
(CH ₃ ) CO ₂ CH (CH ₂ CN) ₂ ). Of these, methacrylate monomers, particularly cyanomethyl methacrylate and 2-cyanoethyl methacrylate, are preferably used.

In the present invention, the (meth) acrylate-based oligomer containing a cyano group refers to a (meth) acrylate-based monomer containing a cyano group, which is usually polymerized from about 2 to 20 and can be polymerized with a photocurable monomer. Refers to an oligomer. The addition amount of the cyano group-containing compound is usually 0.001 to 100 parts by weight based on 1 part by weight of the photocurable monomer,
Preferably it is 0.01 to 100 parts by weight, particularly preferably 0.1 to 10 parts by weight.

The molecular orientation optical component of the present invention generally comprises a liquid monomer composition for polymerization obtained by mixing a photocurable monomer, a cyano group-containing compound, a photopolymerization initiator and, if necessary, an additive. It is manufactured by shaping in a transparent casting mold such as plastic or on a flat plate, followed by polymerization by light irradiation. Hereinafter, a manufacturing method using a casting mold will be described with reference to the drawings. FIG. 1 shows a production example of an optical component 1 in the form of a sheet. A liquid monomer composition 2 in which a photocurable monomer, a cyano group-containing compound, a photopolymerization initiator and the like are mixed is placed on a glass plate 3. Is injected into the frame-shaped spacer 4 and shaped into a sheet. A linear light source 5 is provided parallel (horizontally) to the upper surface of the monomer composition 2 above the monomer composition 2 formed in a sheet shape, and irradiates light in a certain direction to cure the monomer composition 2.

As a light source for light irradiation, a diffused light source is usually used, and light having a distribution of irradiation light amount is applied so that the illuminance of the upper surface on which the monomer composition is formed is inclined. In the present invention, irradiation with light in a certain direction means that the light irradiation angle does not change with time with respect to the upper surface of the shaped monomer composition. Usually, irradiation is performed in a state where the shaped monomer composition and the light source are fixed and allowed to stand. The monomer composition 2 that has been irradiated with light is photocured, and the coexisting cyano group-containing compound is oriented in the direction of the line of the linear light source 5. When a plurality of linear light sources are used, when the linear light sources are installed in parallel with each other (not shown), the compound having a cyano group is oriented in one direction as shown in FIG. Further, as shown in FIG. 2, line light sources 5a and 5
When b is used, the cyano group-containing compound has two orientations orthogonal to each other. Point light source 5 as light source
When c is used, the compound containing a cyano group is oriented concentrically as shown in FIG. When partially forming a molecular orientation state, after selectively irradiating the oriented portion using a mask or the like, curing is performed stepwise by uniformly irradiating the light while rotating the whole. .

The intensity of the irradiation light is determined in consideration of the degree of molecular orientation and the cured area, but is usually several to several hundred mw / cm.
Light in an illumination range of ² is used. The irradiation time is set in consideration of the photocurable monomer to be cured and the film thickness,
Even in the lowest illuminance part of the light intensity distribution, the total irradiation light amount is 1
It is performed so as to be at least mJ / cm ² , that is, to complete the curing. The light irradiation time is usually 1 second to 60 minutes, preferably 10 seconds to 10 minutes, more preferably 1 minute to 5 minutes. In order to improve the degree of curing, post-curing can be performed by applying heat after photocuring. Post-curing is usually 100
C. to 200.degree. C., preferably 150.degree. C. to 180.degree. C., usually for 1 minute to 2 hours, preferably 1 hour to 1 hour 30 minutes. The light source for light irradiation can be appropriately selected according to the characteristic wavelength of the photocurable liquid monomer and the photopolymerization initiator. Generally, an ultraviolet light source such as a high-pressure mercury lamp, a metal halide lamp, or a short arc lamp is used as a point light source or a line light source, but a visible light or an infrared light source such as a laser can be used in combination with a photosensitizer.

Although the principle of the arrangement of the cyano group-containing compounds is not necessarily elucidated, it is presumed that the orientation direction is determined by the following two factors. Molecular structure of a cyano group-containing compound. In particular, the position and bonding direction of the cyano group in the molecule. The intensity distribution of irradiation light during curing and the direction of curing shrinkage. For example, when a relatively linear cyano group-containing compound is used, the light intensity is uniformly arranged in a constant direction in the sheet plane (FIG. 1). On the other hand, in the case of a compound containing a cyano group in the side chain, the arrangement direction having an orientation component also in the sheet thickness direction is considerably affected by the position and bonding direction of the cyano group in the molecule, so that this high dielectric constant site is It is considered that the molecule interacts with the irradiation light, that is, the electromagnetic wave, and determines the orientation direction of the whole molecule. Therefore, in particular, 2
It is presumed that a cyano group-containing compound having two or more cyano groups has a stronger effect of fixing the molecular orientation in one direction.

The orientation direction and degree of the cyano group-containing compound can be controlled by changing the type and amount of the compound, and by changing the intensity distribution and direction of irradiation light during curing. Furthermore, by selectively irradiating light, it is possible to produce a molecularly oriented site at a desired position on a film or sheet. By utilizing this molecular orientation and, for example, two-dimensionally aligning the sheet in the plane of the sheet, a polarizing plate that transmits or absorbs only the polarized light in the orientation direction can be manufactured. The molecular orientation optical component thus obtained is in the form of a sheet having a thickness of usually 0.01 to 10 mm, preferably 0.05 to 5 mm, particularly preferably 0.1 to 3 mm. The degree of polarization is usually at least 50%, preferably at least 70%, particularly preferably at least 90%. The degree of orientation of the molecular orientation optical component of the present invention is such that the degree of decrease in the degree of polarization before and after heating at 150 ° C. for 7 days is usually 30% or less, preferably 10% or less, particularly preferably 1% or less. . The smaller the numerical value of the rate of decrease in the polarization rate, the smaller the rate of decrease in the polarization rate after heating, indicating that the composition is more resistant to thermal stress.

The degree of polarization P (%) and the rate of decrease in the degree of polarization are determined by the following equations.

(Equation 1)

(Equation 2)

(Equation 3)

## EQU4 ## Degree of decrease in degree of polarization = {(degree of polarization before heating)-(degree of polarization after heating)} / (degree of polarization before heating) × 100

In the present invention, the cyano group-containing compound is a (meth) acrylate-based monomer or an oligomer composed of a (meth) acrylate-based monomer. And copolymerize with it. This can prevent the cyano group-containing compound from falling off or sublimating during long-term use or at high temperatures. Therefore, it is possible to provide a high-temperature environment and a long-term stable alignment plate.

According to the present invention, it is lightweight and has a thickness of several μm to
Thickness of several centimeters can be molded even in a large area, can be used for light rays in the visible or infrared region, has a wide range of selectable optical performances, is easy to control, has excellent heat resistance and weather resistance, and is long. Polarization plates, optical communication isolators, refractive index control plates, light condensing plates, components for liquid crystal projectors such as polarizing beam splitters, etc. Can be provided.

[0019]

The following examples serve to illustrate the present invention more specifically. Parts in the examples indicate parts by weight. The polarization transmittance (T) of the molecular orientation sheet described in the examples was determined by irradiating the sheet with linearly polarized light, measuring the transmission intensity, and using the following mathematical expressions 1 and 2. The degree of polarization (P) was determined according to the following equation 3 based on the calculated numerical values.

(Equation 5)

(Equation 6)

(Equation 7)

Example 1 In 50 parts of p-bis (β-methacryloyloxyethylthio) xylylene, 50 parts of 2-cyanoethyl methacrylate, and as a photopolymerization initiator,
0.1 part of 2,4,6-trimethylbenzoyldiphenylphosphine oxide was uniformly stirred and mixed. This composition was poured into a glass mold using a silicon plate having a thickness of 2 mm as a spacer, and irradiated with ultraviolet rays for 3 minutes using a metal halide lamp located at a distance of 40 cm above the glass surface.
After the irradiation, the mold was released to obtain a cured product. The light transmittance of the obtained cured product was 50% in the range of 400 to 900 nm, and the degree of polarization was 70%. After the cured product was heated in an oven at 150 ° C. for 7 days, no decrease was observed in the degree of polarization.

Comparative Example 1 100 parts of p-bis (β-methacryloyloxyethylthio) xylylene was added to 2,3-
0.1 parts of dicyanonaphthalene, as a photopolymerization initiator,
0.1 part of 2,4,6-trimethylbenzoyldiphenylphosphine oxide was uniformly stirred and mixed. A cured product was obtained in the same manner as in Example 1 except that this composition was used. The light transmittance of the obtained cured product is 400 to 900 nm.
And the degree of polarization was 90%. After the cured product was heated in an oven at 150 ° C. for 7 days, the degree of polarization was reduced to 30%.

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining a production example of the present invention.

FIG. 2 is a schematic view for explaining another production example of the present invention.

FIG. 3 is a schematic diagram for explaining a manufacturing example using a point light source.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical component 2 Monomer composition 3 Glass plate 4 Frame spacer 5, 5a, 5b, 5c Light source

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // C08L 33:14 C08L 33:14 (72) Inventor Yutaka Tamura 8-3 Chuo, Ami-cho, Inashiki-gun, Ibaraki Prefecture No. 1 Mitsubishi Chemical Corporation Tsukuba Research Laboratory F term (reference) 2H049 BA02 BA24 BB46 BC05 BC22 2H091 FA07X FA07Z FB02 FB04 LA30 4F071 AA33 AF29Y BA02 BB02 BC01 BC12 4J011 QA03 QA12 QA13 QA22 QA38 QA40 QA45 QA45 SA UA01 UA06 VA01 WA07 4J027 AA02 AE01 AG01 BA07 BA11 BA19 BA25 CB10 CC04 CC05 CD01

Claims (6)

[Claims] 1. A molecule obtained by irradiating a mixture of a (meth) acrylate-based monomer or oligomer containing a cyano group and a photocurable monomer with light in a certain direction to cure the mixture. Oriented optical components. 2. The optical component having a molecular orientation of 0.1 to 3 mm in thickness.
The molecularly oriented optical component according to claim 1, wherein the component is a sheet. 3. The molecularly oriented optical component according to claim 1, wherein the degree of polarization is 50% or more. 4. The photocurable monomer is a monomer or oligomer containing a polyfunctional (meth) acrylate having at least two unsaturated bonds in a molecule as an essential component.
4. The molecular orientation optical component according to any one of the above-mentioned items. 5. A (meth) acrylate-based monomer or oligomer containing a cyano group is mixed with a photocurable monomer, and the mixture is shaped, and then irradiated with light in a certain direction to cure the mixture. And producing a (meth) acrylate monomer or oligomer containing a cyano group. 6. The production method according to claim 5, wherein the irradiation with light is cured by a linear light source provided in parallel with the shaped photocurable monomer surface.