JP2009092825A - Optical laminate - Google Patents

Abstract

[PROBLEMS] To prevent the occurrence of cracks when used in a high temperature environment and the decrease in the degree of polarization when used in a high humidity environment.
A polarizing film having a solidified layer or a cured layer of an organic dye, a pressure-sensitive adhesive layer in contact with the polarizing film, and a substrate that supports the polarizing film and the pressure-sensitive adhesive layer are provided. The organic pigment is preferably a perylene dye exhibiting lyotropic liquid crystallinity. The pressure-sensitive adhesive layer is preferably an acrylic pressure-sensitive adhesive. The pressure-sensitive adhesive layer has a creep amount of 10 μm / h to 300 μm / h.
[Selection] Figure 1

Description

  The present invention relates to an optical laminate including a polarizing film of an organic dye used for a display device or the like.

Polarizing films used for liquid crystal display devices and the like are roughly classified into iodine type and organic type depending on the manufacturing method. The iodine-based polarizing film is easily broken in the stretching direction because a polymer film mainly composed of a polyvinyl alcohol-based resin dyed with iodine is stretched. Then, the method of apply | coating the solution containing an organic pigment | dye on a base material and drying it and manufacturing a polarizing film is known (patent document 1).
JP 2007-061755 A

  The organic polarizing film forms an organic dye layer on the substrate, so if it is used in a high temperature environment and expands and contracts repeatedly, it will crack due to the stress applied to the organic dye layer on the substrate. There is a problem of causing the occurrence of. In addition, there is a problem that the degree of polarization is lowered when used in a high humidity environment and repeated drying and moisture absorption.

  This invention is made | formed in view of the said situation, and it aims at preventing the fall of the polarization degree in the generation | occurrence | production of the crack in the use in a high temperature environment, and the use in a humid environment.

  By arranging the contact layer in contact with the polarizing film of the organic dye, the present inventors can reduce the temperature change and humidity change acting on the polarizing film of the organic dye, thereby causing cracks. It was found that drying and moisture absorption that cause expansion, contraction, and decrease in polarization degree can be prevented.

  That is, the optical layered body of the present invention includes a polarizing film provided with a solidified layer or a cured layer of an organic dye, a contact layer disposed in contact with the polarizing film, and a substrate that supports the polarizing film and the contact layer. And comprising. According to this configuration, by arranging the contact layer in contact with the polarizing film, expansion and contraction of the polarizing film are suppressed, and generation of cracks due to temperature changes can be prevented. Further, by bringing the contact layer into contact with each other, drying and moisture absorption of the polarizing film are suppressed, and a decrease in the degree of polarization due to a change in humidity can be prevented.

  In the present invention, the organic pigment is preferably a perylene dye exhibiting lyotropic liquid crystallinity. The contact layer is preferably an adhesive layer. The contact layer is preferably an adhesive layer made of an acrylic adhesive. Further, the contact layer preferably has a creep amount of 10 μm / h to 300 μm / h.

  Hereinafter, each layer which comprises the optical laminated body of this invention is demonstrated.

(Base material)
As the substrate, any substrate such as a glass plate or a polymer film can be used. The base material may be subjected to any treatment such as orientation treatment or easy adhesion treatment. Examples of the alignment treatment include mechanical alignment treatment such as rubbing treatment, chemical alignment treatment such as photo-alignment treatment, and the like. Examples of the easy adhesion treatment include corona treatment, plasma treatment, and UV treatment. On the other hand, an alignment film may be formed on the substrate. When the alignment film is formed on the substrate, the alignment film is preferably subjected to an alignment treatment.

(Polarizing film)
(1) Optical properties The polarizing film preferably exhibits absorption dichroism at a wavelength of 550 nm. Such a polarizing film is used as a polarizer of a liquid crystal display, for example. The dichroic ratio of the polarizing film is preferably 20 or more, more preferably 30 or more, at a wavelength of 550 nm. Note that the dichroic ratio is such that a linearly polarized measurement light is incident using a spectrophotometer so that the electric field vector of the polarization of the measurement light is parallel and orthogonal to the orientation direction of the optical anisotropic layer. It can be calculated by measuring the transmittance.

(2) Organic dye The polarizing film is a solidified layer or a cured layer of an organic dye. The solidified layer or cured layer is preferably formed from an organic dye exhibiting lyotropic liquid crystallinity. The organic dye exhibiting lyotropic liquid crystallinity is soluble in a solvent and has a property of causing an isotropic phase-liquid crystal phase transition by changing temperature or concentration. The liquid crystal phase is not particularly limited, and examples thereof include a nematic liquid crystal phase, a smectic liquid crystal phase, and a cholesteric liquid crystal phase. The solubility of the organic dye exhibiting lyotropic liquid crystal properties in a solvent is preferably 0.5 mmol to 0.1 mol, and more preferably 5 mmol to 50 mmol, with respect to 100 g of water. The organic dye exhibiting lyotropic liquid crystallinity is preferably water-soluble, and such an organic dye preferably has a hydrophilic substituent in order to impart water solubility to the material. The hydrophilic substituent is preferably at least one substituent selected from the group consisting of —COOM, —SO ₃ M, —PO ₃ M, —OH, and —NH ₂ .
Examples of the organic dye include anthraquinone dyes, azo dyes, perylene dyes, quinophthalone dyes, naphthoquinone dyes, merocyanine dyes, and the like. Of these, a perylene dye is preferably used.

(Contact layer)
Any contact layer may be used as long as it is provided in contact with the polarizing film and can protect the polarizing film by covering the polarizing film. Examples thereof include an adhesive layer and an elastic material layer. When an adhesive layer is used as the contact layer, the contact layer, the polarizing film and the base material are laminated in this order to constitute an optical laminate, whereby the contact layer and the polarizing film are brought into contact with each other to prevent the polarizing film from cracking and the degree of polarization. Not only is the effect of preventing the decrease high, but the optical laminate can be attached to a display device or the like through the contact layer of the pressure-sensitive adhesive layer. In this case, the polarizing film and the base material may be brought into contact with each other and laminated, or may be laminated through an alignment layer or an adhesive layer. Even when an elastic material layer such as rubber is used as the contact layer, the elastic material can be brought into contact with the polarizing film to suppress expansion and contraction of the polarizing film, drying of the polarizing film, and moisture absorption. Hereinafter, a pressure-sensitive adhesive layer suitable for attaching an optical laminate to a display device will be described.

(Adhesive layer)
(1) Composition of pressure-sensitive adhesive Any suitable material may be used as the pressure-sensitive adhesive layer as long as it has a suitable adhesive force. Preferably, the pressure-sensitive adhesive layer is made of an acrylic pressure-sensitive adhesive. The acrylic pressure-sensitive adhesive preferably contains a polymer or copolymer synthesized from an acrylate monomer and / or a methacrylate monomer as a base polymer. In addition, the said acrylic adhesive may contain arbitrary additives, such as a crosslinking agent, antioxidant, and tackifier. Alternatively, the base polymer and the additive may interact to change the composition.

(2) Base polymer As the base polymer of the acrylic pressure-sensitive adhesive, a linear or branched polymer having about 2 to 10 carbon atoms is preferably used. Specific examples thereof include n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, n-pentyl acrylate, isopentyl acrylate and the like.

(3) Crosslinking agent Preferably, the acrylic pressure-sensitive adhesive is crosslinked with a crosslinking agent. The crosslinking agent is preferably a peroxide and / or an isocyanate compound. As the peroxide, diacyl peroxides are preferably used. Examples of commercially available cross-linking agents include “Paroyl” series and “Nyper” series manufactured by NOF Corporation. As the isocyanate compound, xylene diisocyanates are preferably used. Examples of commercially available isocyanate compounds include “Takenate” series manufactured by Mitsui Takeda Chemical Co., Ltd. and “Coronate” series manufactured by Nippon Polyurethane Industry Co., Ltd.

(4) Creep amount If the contact layer creep amount is too large, expansion or contraction of the polarizing film cannot be suppressed, and if it is too small, expansion or contraction of the polarizing film cannot be followed. Since there is a possibility that the contact with the substrate may be separated, it is preferably 10 μm / h to 300 μm / h, more preferably 40 μm / h to 260 μm / h. With such a contact layer, it is considered that the stress applied to the polarizing film can be alleviated by expanding or contracting in synchronization with the polarizing film with respect to the temperature change.

  Note that “creep” refers to a phenomenon in which plastic deformation of a sample increases with time under a constant stress. The amount of creep was 10 mm x 10 mm, and the upper part 10 mm x 10 mm of the sample was attached to a bake plate via an adhesive layer as a contact layer, and after autoclaving at 50 ° C, 5 atm for 15 minutes, at room temperature After being left for 1 hour, the amount of deviation of the sample when a load of 500 g is applied to the lower end of the laminated film at 23 ° C. for 1 hour is calculated. The creep amount of the pressure-sensitive adhesive layer specified in the present specification can be appropriately increased or decreased by changing the molecular weight of the base polymer of the pressure-sensitive adhesive and / or the amount of the crosslinking agent added to the pressure-sensitive adhesive. For example, the amount of creep of the pressure-sensitive adhesive layer can be decreased by increasing the amount of the base polymer or increasing the amount of the crosslinking agent in the pressure-sensitive adhesive. On the other hand, the creep amount of the pressure-sensitive adhesive layer can be increased by reducing the molecular weight of the base polymer or decreasing the amount of the crosslinking agent in the pressure-sensitive adhesive.

  The method for producing an optical layered body of the present invention includes a step of applying a solution containing an organic dye on the surface of a base material and drying to produce a first stack including the base material and a solidified layer of the organic dye. And applying a solution containing an adhesive on the surface of the release liner and drying to produce a second laminate comprising the release liner and the adhesive layer, the first laminate and the first A step of adhering the laminated layer 2 so that the solidified layer and the pressure-sensitive adhesive layer are opposed to and in contact with each other.

  In the method for producing an optical laminate of the present invention, the step of producing the first laminate is preferably performed by applying a solution containing the organic dye on the surface of a substrate that has been subjected to orientation treatment and easy adhesion treatment, and drying. Is. Or the process of producing the said 1st lamination | stacking apply | coats the solution containing an organic pigment | dye to the surface of the base material in which the alignment film was formed preferably, and is made to dry.

  The release liner is peeled off when the optical layered body of the present invention is attached to any desired object. In the meantime, the release liner is left to prevent the adhesive layer from being contaminated. Can do.

  Applications of the optical laminate of the present invention include, for example, OA equipment such as personal computer monitors, notebook personal computers, and copy machines, mobile phones, watches, digital cameras, personal digital assistants (PDAs), portable equipment such as portable game equipment, and video cameras. Household appliances such as TVs and microwave ovens, back monitors, monitors for car navigation systems, in-vehicle devices such as car audio, display equipment such as information monitors for commercial stores, alarm equipment such as monitoring monitors, nursing care Care and medical equipment such as monitors and medical monitors. The polarizing film may be used after being peeled off from the substrate, or may be used as a laminate. When the laminated body is used for optical applications, the support is preferably transparent in the visible light wavelength region.

  According to the present invention, by arranging the contact layer in contact with the polarizing film, expansion and contraction of the polarizing film are suppressed, and generation of cracks due to temperature changes can be prevented. Further, by arranging the contact layers in contact with each other, the polarizing film can be protected and drying and moisture absorption of the polarizing film can be suppressed, and a decrease in the degree of polarization due to humidity change can be prevented.

Example 1
Corona treatment [discharge amount: 349 W · min / m ² ] is applied to a film whose main component is a norbornene-based resin having a thickness of 100 μm [trade name “ZEONOR” manufactured by Nippon Zeon Co., Ltd.], and the treated surface contains a perylene dye. An aqueous solution having a concentration of 12% by weight [trade name “NO15” manufactured by Optiva, Inc.] was applied at a coating speed of 20 m / min using Mayer Rod (# 1.5) [manufactured by BUSCHMAN], dried, and norbornene-based A first laminate including a film mainly composed of a resin and a solidified layer (thickness 0.5 μm) containing a perylene dye was produced.

  The following pressure-sensitive adhesive (1) was applied to the surface of the release liner and dried to produce a second laminate comprising a release liner and a pressure-sensitive adhesive layer (thickness 25 μm).

  Next, the second stack and the first stack are bonded so that the solidified layer and the pressure-sensitive adhesive layer face each other and come into contact with each other, and the first stack almost covers the entire surface of the second stack. A laminate (i) arranged so as to be covered was produced. FIG. 1 is a diagram showing a layer structure of a laminate (i), in which reference numeral 10 denotes an adhesive layer constituting the second laminate, and reference numeral 20 denotes a solidified layer containing a perylene dye constituting the first laminate (polarized light). Membrane) and reference numeral 30 indicate a film (base material) constituting the first laminate. The film 30 may or may not be in contact with the solidified layer 20. For example, as shown in FIG. 2, an arbitrary layer 40 such as a light distribution film or an adhesive layer may be disposed between the film 30 and the solidified layer 20.

(Example 2)
A laminate (ii) was produced in the same manner as in Example 1 except that the following adhesive (2) was used instead of the adhesive (1).

(Example 3)
A laminate (iii) was produced in the same manner as in Example 1 except that the following adhesive (3) was used in place of the adhesive (1).

(Comparative Example 1)
A laminate (iv) is produced in the same manner as in Example 1 except that the first laminate and the second laminate are pasted so that the substrate and the pressure-sensitive adhesive layer face each other and come into contact with each other. (See FIG. 3).

(Composition of pressure-sensitive adhesives (1) to (3))
Table 1 shows the compositions of the pressure-sensitive adhesives (1) to (3) used in Examples 1 to 3 and Comparative Example 1, respectively. These pressure-sensitive adhesives were synthesized by a thermal polymerization reaction in a toluene solution at 60 ° C. for 8 hours in the presence of a polymerization initiator.

Compounding ratio: Units are by weight BA: Butyl acrylate HEA: 2-hydroxyethyl acrylate ACMO: Acrylylmorpholine
AA: Acrylic acid HBA: 4-Hydroxybutyl acrylate Coronate L: Product name “Coronate L” manufactured by Nippon Polyurethane Industry Co., Ltd.
BMT40SV: Product name “Nyper BMT40SV” manufactured by NOF Corporation
D110N: Trade name “Takenate D110N” manufactured by Mitsui Takeda Chemical Co., Ltd.
A-100: Product name “A-100” manufactured by Soken Chemical Co., Ltd.

(Evaluation)
The laminates (i) to (iv) according to Examples and Comparative Examples were bonded to a glass plate through the pressure-sensitive adhesive layer while removing the release liner, and samples (i) to (iv) were produced. Samples were prepared for the next crack test and the polarization degree change test, respectively.

(High temperature durability test)
The samples (i) to (iv) were stored in a constant temperature room at 80 ° C. for 500 hours. Thereafter, the samples (i) to (iv) were taken out from the high temperature chamber and left at room temperature for 30 minutes, and then the presence or absence of cracks in the polarizing film was confirmed by visual observation.

(High humidity durability test)
The samples (i) to (iv) were stored in a constant temperature and humidity chamber at 60 ° C. and 90% RH for 500 hours. Thereafter, samples (i) to (iv) were taken out from the high humidity chamber and allowed to stand at room temperature for 30 minutes, and then the degree of polarization was measured to determine the change in degree of polarization.

  Table 2 shows the results of the high temperature durability test and the high humidity durability test of samples (i) to (iv).

(Measurement method of creep amount of adhesive layer)
The upper 10 mm × 10 mm of the sample cut to 10 mm × 30 mm was attached to a baking plate via an adhesive layer, and after autoclaving at 50 ° C., 5 atm, 15 minutes, left at room temperature for 1 hour, then 23 ° C. Then, the amount of deviation of the sample when a load of 500 g was applied to the lower end of the laminated film for 1 hour was measured. (Laser type creep testing machine)

(Measurement method of degree of polarization)
For the degree of polarization of the laminated film, two samples of the laminated film prepared under the same conditions are prepared, and a high-speed integrating sphere type spectral transmittance measuring device [product name “Dot-3C” manufactured by Murakami Color Research Laboratory Co., Ltd.] is used. , Tp and Tc were measured and determined from the following equations.
P = {(Tp−Tc) / (Tp + Tc)} ^1/2 × 100
Tp represents the light transmittance when the absorption axes of the two laminated films are parallel, and Tc represents the light transmittance when the absorption axes of the two laminated films are orthogonal.

(Measurement method of polarization degree change)
The change in polarization degree was calculated from {polarization degree after test (P ₅₀₀ ) −polarization degree before test (P ₀ )}. The above _{P 500} is, 80 ° C. of the temperature-controlled room or 60 ° C., in a constant-temperature constant-humidity chamber of RH 90%, expressed after storage for 500 hours, the degree of polarization of the sample.

The figure which shows the layer structure of the optical laminated body which concerns on embodiment of this invention The figure which shows the other layer structure of the optical laminated body which concerns on embodiment of this invention The figure which shows the layer structure of the optical laminated body which concerns on the comparative example of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Adhesive layer 20 Polarizing film 30 Base material 40 layer

Claims (9)

A polarizing film comprising a solidified layer or a cured layer of an organic dye;
A contact layer disposed in contact with the polarizing film;
An optical laminate comprising: the polarizing film and a substrate that supports the contact layer.   The optical laminate according to claim 1, wherein the organic pigment is a perylene dye exhibiting lyotropic liquid crystallinity.   The optical laminate according to claim 1, wherein the contact layer is a pressure-sensitive adhesive layer.   The optical laminate according to claim 3, wherein the contact layer is an adhesive layer made of an acrylic adhesive.   The optical laminate according to claim 1, wherein the contact layer has a creep amount of 10 μm / h to 300 μm / h. Applying a solution containing an organic dye on the surface of the substrate, drying, and preparing a first laminate including the substrate and a solidified layer of the organic dye; and
Applying a solution containing a pressure-sensitive adhesive to the surface of the release liner, drying, and preparing a second laminate including the release liner and the pressure-sensitive adhesive layer;
The manufacturing method of the optical laminated body including the process of sticking the said 1st lamination | stacking and said 2nd lamination | stacking so that the said solidification layer and the layer of the said adhesive may oppose and contact.   The method for producing an optical laminate according to claim 6, wherein the step of producing the first laminate is performed by applying a solution containing the organic dye on the surface of the substrate subjected to the alignment treatment and drying the solution.   The method for producing an optical laminate according to claim 6, wherein the step of producing the first laminate is performed by applying a solution containing the organic dye on the surface of the base material subjected to the easy adhesion treatment and drying the solution.   The method for producing an optical laminate according to claim 6, wherein the step of producing the first laminate is performed by applying a solution containing an organic dye to the surface of the substrate on which the alignment film is formed, and drying the solution.

Images