JP2010122315A - Optical laminated body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical laminated body, having both hardness and flexibility to prevent a sheet polarizer from being damaged and prevent the occurrence of cracks. <P>SOLUTION: The optical laminated body includes a light transmitting base material and a protective layer provided on the light transmitting base material. The light transmitting base material is formed of at least one kind selected from a group of polyethylene terephthalate, polyethylene naphthalate, polybuthylene terephthalate, polycarbonate and cycloolefin polymer. The protective layer includes a compound expressed by a general formula (A) (wherein A indicates a bonding group having a chain structure having four or more atoms in the main chain, and R<SP>1</SP>and R<SP>2</SP>indicate an isocyanate radical, a hydrogen atom or a hydrocarbon radical) and ultraviolet curable resin formed of a urethane polymer obtained from bifunctional or more acrylate having a hydroxyl group reactive with the isocyanate radical of the general formula (A). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to an optical laminate.

Image display devices such as cathode ray tube display (CRT), liquid crystal display (LCD), plasma display (PDP), electroluminescence display (ELD), etc. are generally displayed when the surface is damaged by external contact. In some cases, the visibility of the displayed image is reduced. For this reason, a protective layer is generally laminated on the surface for surface protection.

As such a surface protective film, Patent Document 1 discloses a polarizing plate provided with a protective layer made of an ultraviolet curable epoxy acrylate resin having a certain degree of hardness.

However, since the ultraviolet curable epoxy acrylate resin has a tendency to become brittle as the hardness increases, there is a problem that even if a slight bending occurs during the manufacturing process or use, a crack is generated. .

On the other hand, Patent Document 2 discloses a protective film for a polarizing plate including a base material made of triacetyl cellulose and a protective layer laminated on the base material. However, it does not describe forming a protective layer on other base materials.
JP-A-5-341123 Japanese Patent No. 3476165

In view of the above-mentioned present situation, the present invention provides an optical laminate that can prevent the surface of an image display device from being damaged and also prevent cracks from occurring by combining hardness and flexibility. It is the purpose.

The present invention is an optical laminate having a light-transmitting substrate and a protective layer provided on the light-transmitting substrate, the light-transmitting substrate comprising polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, Polycarbonate, cycloolefin polymer, polyethersulfone, polysulfone, polyetherketone, polyether, polyamideimide, polyimide, acrylic resin, epoxy resin, polyamide, polyacetal, syndiotactic polystyrene, polyphenylene sulfide, polyetheretherketone, liquid crystal polymer , Fluororesin, polyether nitrile, modified polyphenylene ether and polyetherimide, and the protective layer has the following general formula (A)

(In the formula, A represents a linking group having a chain structure in which the number of atoms in the main chain is 4 or more, and R ¹ and R ² represent an isocyanate group, a hydrogen atom, or a hydrocarbon group.)
And an ultraviolet curable resin formed from a urethane polymer obtained from a bifunctional or higher functional acrylate having a hydroxyl group capable of reacting with the isocyanate group of the general formula (A). It is a laminate.

The compound represented by the general formula (A) includes trimethylolpropane, pentaerythritol or dipentaerythritol, and the following general formula (B)

(In the formula, n represents an integer of 6 to 20.)
It is preferable that it is a compound obtained by reaction with the compound represented by these.
The acrylate is an ester compound of a polyhydric alcohol having three or more hydroxyl groups and acrylic acid or methacrylic acid, and preferably has one hydroxyl group.
Hereinafter, the present invention will be described in detail.

The light transmissive substrate constituting the optical laminate of the present invention is polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polycarbonate, cycloolefin polymer, polyethersulfone, polysulfone, polyetherketone, polyether, polyamideimide, polyimide At least selected from the group consisting of acrylic resin, epoxy resin, polyamide, polyacetal, syndiotactic polystyrene, polyphenylene sulfide, polyether ether ketone, liquid crystal polymer, fluororesin, polyether nitrile, modified polyphenylene ether and polyetherimide It consists of one kind. The light-transmitting substrate generally has a thickness of about 10 to 300 μm, preferably about 30 to 200 μm.

Examples of the cycloolefin polymer include a norbornene polymer, a monocyclic olefin polymer, a cyclic conjugated diene polymer, and a vinyl alicyclic hydrocarbon polymer. Commercially available products of the cycloolefin polymer include ZEONEX and ZEONOR (norbornene polymer) manufactured by Nippon Zeon Co., Ltd., Sumilite FS-1700 manufactured by Sumitomo Bakelite Co., Ltd. Polymer), Appell (cyclic olefin copolymer) manufactured by Mitsui Chemicals, Topas (cyclic olefin copolymer) manufactured by Ticona, Optretz OZ-1000 series manufactured by Hitachi Chemical Co., Ltd. (alicyclic) Acrylic resin), FV series manufactured by Asahi Kasei Chemicals Corporation, and the like.

The protective layer constituting the optical laminate of the present invention has the following general formula (A)

(In the formula, A represents a linking group having a chain structure in which the number of atoms in the main chain is 4 or more, and R ¹ and R ² represent an isocyanate group, a hydrogen atom, or a hydrocarbon group.)
And an ultraviolet curable resin formed from a urethane polymer obtained from a bifunctional or higher functional acrylate having a hydroxyl group capable of reacting with the isocyanate group of the general formula (A).

In the general formula (A), A represents a linking group having a chain structure in which the number of atoms in the main chain is 4 or more.
The number of atoms of the main chain represented by A is preferably 10 to 100, more preferably 15 to 60.
R ¹ and R ² each independently represent an isocyanate group, a hydrogen atom or a hydrocarbon group.
R ¹ and R ² are preferably isocyanate groups.

The general formula (A) includes trimethylolpropane, pentaerythritol or dipentaerythritol, and the following general formula (B)

(In the formula, n represents an integer of 6 to 20.)
It is preferable that it is a compound obtained by reaction with the compound represented by these.

In the said general formula (B), n represents the integer of 6-20.
The above n is preferably 8 to 18, more preferably 10 to 16.

Specific examples of the compound obtained by the reaction of trimethylolpropane, pentaerythritol or dipentaerythritol with the compound represented by the general formula (B) include the following formulas (a-1) and (a-2 ), Formula (a-3)

Etc.

The protective layer constituting the optical layered body of the present invention is obtained from the compound represented by the general formula (A) and a bifunctional or higher functional acrylate having a hydroxyl group capable of reacting with the isocyanate group of the general formula (A). It contains an ultraviolet curable resin formed from a urethane polymer.

The acrylate is bifunctional or higher having a hydroxyl group capable of reacting with the isocyanate group of the general formula (A).
The acrylate is an ester compound of a polyhydric alcohol having three or more hydroxyl groups and acrylic acid or methacrylic acid, and preferably has one hydroxyl group.
Examples of the polyhydric alcohol include glycerin, trimethylolpropane, pentaerythritol, dipentaerythritol and the like.
Examples of the acrylate include pentaerythritol triacrylate, dipentaerythritol pentaacrylate, and 2-hydroxy-1-acryloxy-3-methacrylate.

If desired, the protective layer may use fillers such as organic fine particles and inorganic fine particles in order to add antiglare properties.
Examples of the organic fine particles include styrene resin, styrene-acrylic copolymer resin, acrylic resin, divinylbenzene resin, silicone resin, urethane resin, melamine resin, styrene-isoprene resin, benzoguanamine resin, and the like as main components. Can be used.

The type of the inorganic fine particles is not particularly limited, and examples thereof include silica, alkali metal oxide, alkaline earth oxide, titanium oxide, zinc oxide, aluminum oxide, boron oxide, tin oxide, Phosphorus oxide, indium tin oxide, zirconium oxide, metal, metal nitride, carbon isotope, fine silicate, calcium silicate, aluminum silicate, calcium carbonate, magnesium carbonate, fine talc, titanium oxide, diatomaceous earth, smectite, kaolin clay Etc.

Although the formation method of the said protective layer is not specifically limited, For example, it obtains by mixing the urethane polymer obtained from the compound represented with the said general formula (A), and the said acrylate, a photoinitiator, a solvent, and arbitrary components. It can form by apply | coating the composition for protective layer formation on the transparent base material. Solvents include alcohols such as isopropyl alcohol, methanol and ethanol; ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; esters such as methyl acetate, ethyl acetate and butyl acetate; halogenated hydrocarbons; toluene, xylene and the like Aromatic hydrocarbons; or mixtures thereof.
The photopolymerization initiator is not particularly limited, and known ones can be used. For example, benzoins such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, acetophenone, 2,2-dimethoxy- Acetophenones such as 2-phenylacetophenone and 2,2-diethoxy-2-phenylacetophenone, anthraquinones such as 2-methylanthraquinone, 2-ethylanthraquinone and 1-chloroanthraquinone, 2,4-dimethylthioxanthone, 2,4- Thioxanthones such as diethylthioxanthone and 2-chlorothioxanthone, ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal, benzophenone, 1-hydroxycyclohexyl phenyl ketone, 1- (4- Hydroxy ketones such as sopropylphenyl) -2-hydroxy-2-methyl-propan-1-one and 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 2,4,6-trimethylbenzoyl Examples include phosphine oxides such as -diphenylphosphine oxide and bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide. The said photoinitiator may be used independently and may use 2 or more types together.

The composition for forming a protective layer can be applied by a known coating method such as a Miya bar coating method, a roll coating method, or a gravure coating method. After application of the protective layer forming composition, drying and curing with ultraviolet rays are performed. Curing with ultraviolet rays can be performed, for example, with a metal halide lamp, a high-pressure mercury lamp, a low-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a carbon arc lamp, a black light fluorescent lamp, or the like.

According to the present invention, the light transmissive substrate is polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polycarbonate, cycloolefin polymer, polyethersulfone, polysulfone, polyetherketone, polyether, polyamideimide, polyimide, acrylic resin, Consists of at least one selected from the group consisting of epoxy resin, polyamide, polyacetal, syndiotactic polystyrene, polyphenylene sulfide, polyether ether ketone, liquid crystal polymer, fluororesin, polyether nitrile, modified polyphenylene ether and polyether imide Therefore, the transparency and mechanical strength of the optical laminate can be increased. Moreover, since it has the above-mentioned specific protective layer, it is possible to prevent the surface of the image display device from being damaged and to prevent the occurrence of cracks.

The optical laminate according to the present invention is provided on the outermost surface of the image display device. The image display device may be a non-self-luminous image display device such as an LCD, or a self-luminous image display device such as a PDP, FED, ELD (organic EL, inorganic EL), or CRT.

An LCD as a typical example of the non-spontaneous light emission type includes a transmissive display body and a light source device that irradiates the transmissive display body from the back. When the image display device is an LCD, the optical laminate of the present invention is formed on the surface of the transmissive display.

When the image display device is a liquid crystal display device having the optical laminate, the light source of the light source device is irradiated from the lower side of the optical laminate. Note that in the STN liquid crystal display device, a retardation plate may be inserted between the liquid crystal display element and the polarizing plate. An adhesive layer may be provided between the layers of the liquid crystal display device as necessary.

By providing the optical laminate according to the present invention on the surface of the polarizing element on the surface opposite to the surface on which the protective layer is present in the optical laminate, a polarizing plate can be obtained.

The polarizing element is not particularly limited, and for example, a polyvinyl alcohol film, a polyvinyl formal film, a polyvinyl acetal film, an ethylene-vinyl acetate copolymer saponified film, etc. dyed and stretched with iodine or the like can be used. In the laminating process of the polarizing element and the optical laminate of the present invention, it is preferable to saponify the light-transmitting substrate (preferably a triacetyl cellulose film). By the saponification treatment, the adhesiveness is improved and an antistatic effect can be obtained.

The PDP which is the spontaneous emission type image display device includes a front glass substrate and a rear glass substrate disposed with a discharge gas sealed between the front glass substrate and the front glass substrate. When the image display device is a PDP, the above-described optical laminate is provided on the surface of the surface glass substrate or the front plate (glass substrate or film substrate).

The self-luminous image display device is an ELD device that emits light when a voltage is applied, such as zinc sulfide and a diamine substance: a phosphor is deposited on a glass substrate, and the voltage applied to the substrate is controlled. It may be an image display device such as a CRT that converts light into light and generates an image visible to the human eye. In this case, the optical laminated body described above is provided on the outermost surface of each display device as described above or the surface of the front plate.

In any case, the image display device can be used for display of a television, a computer, a word processor, or the like. In particular, it can be suitably used for the surface of high-definition image displays such as CRTs, liquid crystal panels, PDPs, and ELDs.

With the optical layered body of the present invention, it is possible to prevent the surface of the image display device from being damaged and to prevent the occurrence of cracks.

EXAMPLES Hereinafter, although this invention is demonstrated in more detail based on an Example, this invention is not limited only to these Examples. In the examples, “parts” means “parts by weight” unless otherwise specified.

Example 1
The following protective layer coating liquid (A) is applied to a thickness of about 5 μm on a polyester (A4300, manufactured by Toyobo) film having a thickness of about 188 μm using a normal applicator, and then dried and cured by irradiating with ultraviolet rays. Thus, an optical laminate was prepared.

<Protective layer coating solution (A)>
Polymer F9 100 parts Photopolymerization initiator (Irgacure 184, manufactured by Ciba Specialty Chemicals) 5 parts Isopropyl alcohol 50 parts Methyl ethyl ketone 50 parts

The polymer F9 is a 9-functional urethane polymer obtained by urethane-polymerizing pentaerythritol triacrylate with an addition compound of hexamethylene diisocyanate and trimethylolpropane.

(Example 2)
An optical laminate was produced in the same manner as in Example 1 except that the polymer F9 was replaced with the polymer F15.

The polymer F15 is a 15-functional urethane polymer obtained by urethane-polymerizing pentaerythritol pentaacrylate with an addition compound of hexamethylene diisocyanate and trimethylolpropane.

(Example 3)
An optical laminate was prepared in the same manner as in Example 1 except that the 15-functional urethane polymer (polymer F15) used in Example 2 was used and 50 parts of porous silica gel was added to the protective layer coating solution.

Example 4
The protective layer coating solution (A) is applied to a polybutylene terephthalate [PBT] film having a thickness of about 100 μm with a thickness of about 5 μm using a normal applicator, and then dried and cured by irradiating with ultraviolet rays. An optical laminate was prepared.

(Example 5)
The protective layer coating solution (A) is applied to a thickness of about 5 μm on a polycarbonate [PC] film having a thickness of about 100 μm using a normal applicator, and then dried and cured by irradiating with ultraviolet rays to optically. A laminate was created.

(Example 6)
The protective layer coating solution (A) is applied to an amorphous olefin polymer (Cyclo-Olefin-Polymer: COP) film having a thickness of about 60 μm with a thickness of about 5 μm using a normal applicator, and then ultraviolet rays are applied. Was dried and cured to produce an optical laminate.
ZEONOR manufactured by Nippon Zeon Co., Ltd. was used for the amorphous olefin polymer film.

(Example 7)
The protective layer coating solution (A) is applied to a polyethylene naphthalate [PEN] film having a thickness of about 100 μm to a thickness of about 5 μm using a normal applicator, and then dried and cured by irradiation with ultraviolet rays. An optical laminate was prepared.

(Comparative Example 1)
The following protective layer coating solution (B) is applied to a thickness of about 7 μm on a polyester film (A4300, manufactured by Toyobo Co., Ltd.) having a thickness of about 188 μm using a normal applicator, and then dried and cured by irradiation with ultraviolet rays. Thus, an optical laminate was prepared.

<Protective layer coating solution (B)>
Dipentaerythritol pentaacrylate 100 parts Polyfunctional aromatic isocyanate (Coronate L, manufactured by Nippon Polyurethane Co., Ltd.) 1 part Photopolymerization initiator (Darocur 1173, manufactured by Ciba Specialty Chemicals) 5 parts

(Comparative Example 2)
An optical laminate was prepared in the same manner as in Comparative Example 1 except that Irgacure 184 (manufactured by Ciba Specialty Chemicals) was used as the photopolymerization initiator and the amount of colloidal silica added was 5 parts.

(Comparative Example 3)
An optical laminate was prepared in the same manner as in Comparative Example 1 except that the amount of colloidal silica added was 10 parts.

(Comparative Example 4)
Apply a protective layer coating solution (C) to a thickness of about 7 μm on a polyester (A4300, manufactured by Toyobo) film with a thickness of about 188 μm using a normal applicator, and then dry and cure by irradiating with ultraviolet rays. An optical laminate was prepared.
<Protective layer coating solution (C)>
Isocyanuric acid EO-modified triacrylate (trifunctional) 100 parts Photopolymerization initiator (Darocur 1173, manufactured by Ciba Specialty Chemicals) 5 parts Isopropyl alcohol 50 parts Methyl ethyl ketone 50 parts

(Test example)
The optical laminates obtained from the examples and the comparative examples were tested as follows.
Adhesion test Adhesion was evaluated by a cellophane tape peeling test.
In Table 1, n / 100 indicates that the number of times that peeling of the protective layer was not observed was performed n times by performing 100 peeling tests.

Measurement of hardness The pencil hardness was measured according to "Pencil scratch test" of JIS K5400.

90 [deg.] And 180 [deg.] Bending test The number of cracks after the sample film was bent by pressing it against a 90 [deg.] And 180 [deg.] Jig with the protective layer on the outside was judged visually.
(Evaluation criteria)
○: No crack △: Small number of cracks ×: Many cracks

From Table 1, the optical laminated bodies of Examples 1 to 7 have both hardness and flexibility. The optical laminated bodies of Comparative Examples 1 to 4 are about the same or inferior in hardness to those of Examples 1 to 7. Moreover, about plasticity, it is inferior compared with the thing of Examples 1-7.

The optical layered body of the present invention can be used as a film for protecting a surface of a cathode ray tube display (CRT), a liquid crystal display (LCD), a plasma display (PDP), an electroluminescence display (ELD) or the like.

Claims (3)

An optical laminate having a light transmissive substrate and a protective layer provided on the light transmissive substrate,
The light-transmitting substrate is polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polycarbonate, cycloolefin polymer, polyethersulfone, polysulfone, polyetherketone, polyether, polyamideimide, polyimide, acrylic resin, epoxy resin, polyamide Consisting of at least one selected from the group consisting of polyacetal, syndiotactic polystyrene, polyphenylene sulfide, polyether ether ketone, liquid crystal polymer, fluororesin, polyether nitrile, modified polyphenylene ether and polyether imide,
The protective layer has the following general formula (A)

(In the formula, A represents a linking group having a chain structure in which the number of atoms in the main chain is 4 or more, and R ¹ and R ² represent an isocyanate group, a hydrogen atom, or a hydrocarbon group.)
And an ultraviolet curable resin formed from a urethane polymer obtained from a bifunctional or higher functional acrylate having a hydroxyl group capable of reacting with the isocyanate group of the general formula (A). Laminated body. The compound represented by the general formula (A) includes trimethylolpropane, pentaerythritol or dipentaerythritol, and the following general formula (B):

(In the formula, n represents an integer of 6 to 20.)
The optical laminate according to claim 1, which is a compound obtained by a reaction with a compound represented by the formula: 3. The optical laminate according to claim 1, wherein the acrylate is an ester compound of a polyhydric alcohol having three or more hydroxyl groups and acrylic acid or methacrylic acid, and has one hydroxyl group.