JPH09302144A - Resin composition cured by energy radiation and triacetylcellulose film having - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject curing resin composition excellent in adhesiveness and durability without reducing hard coating properties and useful for polarizing plates, etc., by blending an energy radiation curing resin containing a monomer having plural functional groups with a cellulose-based resin in a specific ratio. SOLUTION: This resin composition contains (B) 2-10 pts.wt. of a cellulose- based resin such as methylcellulose based on (A) 100 pts.wt. of an energy radiation curing resin containing a monomer having >=5 functional groups such as dipentaerythritol hexa(meth)acrylate. It is preferable to form a cured film layer of the energy radiation curing resin composition on an acetylcellulose film.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an energy ray curable resin composition, a triacetyl cellulose film having a cured film layer of the composition, a polarizing plate using the above film, and an elliptically polarizing plate. The film of the present invention is L
It is useful as a scratch-resistant film and a non-glare film used on the surface of various display bodies such as CDs, CRTs and plasma displays.

[0002]

2. Description of the Related Art Various display elements such as LCD, CRT, and plasma display are designed so that visual information such as characters and figures can be observed through a protective substrate (having a transparent or non-glare layer) on the surface thereof. In particular, a polarizing element that functions as an optical shutter is provided on the surface of a display body such as a liquid crystal display, but since the polarizing element itself is inferior in scratch resistance, a transparent plastic film (generally a triacetyl cellulose film). , I.e., TAC film is used). However, this transparent plastic film itself is also inferior in scratch resistance, and in recent years,
A polarizing plate having such a scratch-resistant surface has been developed. Such a technique is disclosed in, for example, Japanese Patent Laid-Open No. 1-10.
5738, JP-A-6-157791, and JP-A-7-294740.

Japanese Unexamined Patent Publication (Kokai) No. 1-105738 discloses a polarizing plate which is attached to a film-like polarizing element.
A triacetyl cellulose film (hereinafter abbreviated as TAC film) is used as a transparent protective film having scratch resistance and non-glare property. This film is a TAC film having excellent scratch resistance by providing a cured coating film made of an ultraviolet curing epoxy acrylate resin on one surface of an unsaponified TAC film.

In Japanese Unexamined Patent Publication No. 6-157791, a coating composition containing 10 parts by weight or more and 100 parts by weight or less of a cellulosic resin as a solvent drying type resin with respect to 100 parts by weight of an ionizing radiation curable resin is formed on a TAC film. It is applied and irradiated with ionizing radiation to cure the coating film, thereby imparting scratch resistance. However, the cellulosic resin contributes to the improvement of the adhesion between the coating film and the TAC film, and addition of 10 parts by weight or more rather lowers the scratch resistance.

In Japanese Patent Laid-Open No. 7-294740, the addition of a cellulosic resin contributes to the adhesion to a non-glare layer formed on a TAC film, but in the examples, 1 is added to 100 parts by weight of an ultraviolet curable resin. The hardness of the coating film at 0.5 parts by weight is shown. However, 1.5 parts by weight is insufficient for improving the adhesion under high durability conditions.

[0006]

In order to improve the adhesion to a TAC film when forming a hard coat layer (a non-glare layer containing a filler) for imparting scratch resistance on a TAC film. In addition, the surface of the TAC film was slightly dissolved by using a solvent such as ethyl acetate or methyl ethyl ketone that dissolves the TAC film to improve the adhesion between the TAC film and the hard coat layer. There is a problem that the transparency of the TAC film is impaired due to whitening.

When a resin composition in which a light diffusing material is dispersed is used as the resin composition for the hard coat layer, TAC
There is a problem that the adhesion to the film is reduced.

[0008]

Means for Solving the Problems As a result of intensive studies in view of the above, the present inventors have found that an energy ray curable resin composition in which adhesion to a TAC film is significantly improved without lowering hard coat properties. The present invention has been completed and the present invention has been completed. That is, the present invention provides (1) an energy ray curable resin composition containing 2 to 10 parts by weight of a cellulosic resin with respect to 100 parts by weight of an energy ray curable resin composed of a monomer having 5 or more functional groups, ( 2) The energy ray curable resin composition of (1) or (14), wherein the content of the monomer having 5 or more functional groups in the energy ray curable resin composition excluding the solvent is 40 to 65% by weight. 3) The energy ray curable resin composition of (1) or (2) or (14), wherein the monomer having 5 or more functional groups is an acrylic monomer, and (4) a monofunctional (meth) acrylic monomer. The content of the monofunctional (meth) acrylic monomer in the energy ray-curable resin composition of (1) to (3) and the energy ray-curable resin composition (5) excluding the solvent is 5 to 30% by weight. (4 Or energy ray-curable resin composition (14), containing (6) the light diffusing material (1)
To (5) or (14) the energy ray-curable resin composition, (7) the energy ray-curable resin composition (6) or (14) in which the light diffusing material is silica particles or organic polymer particles, 8) The energy ray-curable resin composition of (6) or (7) or (14), wherein the content of the light diffusing material in the energy ray-curable resin composition excluding the solvent is 0.1 to 30% by weight. (9) A triacetyl cellulose film having a cured film layer of the energy ray curable resin composition according to (1) to (8) or (14), and (10) a cured film layer provided with an antireflection layer. (9) a triacetyl cellulose film, (11) a polarizing plate having a triacetyl cellulose film layer of (9) or (10), (1
2) The polarizing plate of (11), wherein the polarizing plate is an elliptically polarizing plate,
3) A liquid crystal display device having the film of (11) or (12).

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The energy ray-curable resin composition of the present invention is a resin composition which is cured by irradiation with energy rays such as ultraviolet rays and electron rays. This energy ray-curable resin composition contains a monomer having five or more functional groups and a cellulosic resin as essential components. Examples of the monomer having 5 or more functional groups include, for example, 5 or more functional groups (meth).
Acrylic monomers having 5 or more functional groups such as acrylates can be used. Specific examples thereof include dipentaerythritol hexa (meth) acrylate, dipentaerythritol monohydroxypentaacrylate, hexa (meth) acrylate obtained by reacting dipentaerythritol with ε-caprolactone, and trifunctional or higher functional (meth) acrylate (for example, Examples thereof include a reaction product of trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, etc. and an organic polyisocyanate (eg, tolylene diisocyanate, xylylene diisocyanate, etc.). The content of the pentafunctional or higher (meth) acrylate in the resin composition is 40 to 65% by weight.
Is preferred, and particularly preferably 45 to 65% by weight.
When the content of the pentafunctional or higher (meth) acrylate is less than 40% by weight, the hardness and scratch resistance of the UV cured film cannot be obtained.

Specific examples of the cellulosic resin used in the present invention include nitrocellulose, methyl cellulose, ethyl cellulose, ethyl hydroxyethyl cellulose,
Acetyl cellulose, cellulose acetate propionate and the like can be mentioned. The content ratio of the cellulosic resin in the resin composition is 2 to 1 from the viewpoint of adhesion and hardness of the cured film.
0 wt%, preferably more than 2 wt% and less than 10 wt%, more preferably 3 wt% or more and less than 10 wt%, and further preferably about 3 to 9.5 wt%. Further, toluene can be used as a solvent for dissolving the cellulose resin. This solvent can improve adhesion without dissolving TAC, and thus can prevent whitening of TAC.

The energy ray-curable resin composition of the present invention may contain a monofunctional (meth) acrylic monomer as needed, for example, when it is necessary to reduce the viscosity. Examples of monofunctional (meth) acrylic monomers include 2-hydroxypropyl (meth) acrylate, cyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, (meth) acryloylmorpholine, tetrahydrofurfuryl (meth) acrylate, Caprolactone-modified tetrahydrofurfuryl (meth) acrylate, t-butylaminoethyl (meth) acrylate, 2-cyano (meth) acrylate, N, N
-Dimethylaminoethyl (meth) acrylate, N, N
-Such as dimethyl acrylamide. The content ratio of the monofunctional (meth) acrylate in the resin composition is 5 to 30.
%, Preferably 10 to 25% by weight. When the content of the monofunctional (meth) acrylate is less than 5% by weight, the adhesion of the ultraviolet curable coating to the substrate becomes insufficient, and when it exceeds 30% by weight, the hardness of the cured coating becomes insufficient, which is not preferable.

In addition, the energy ray-curable resin composition of the present invention may contain a light diffusing agent, if necessary, for example, to impart nonglare property. Examples of the light diffusing agent include silica particles and organic polymer particles. Examples of the organic polymer particles include polymethylmethacrylate particles, polystyrene particles, polyamideimide particles, and silicone particles. The content of the light diffusing agent in the energy ray-curable resin composition excluding the solvent is appropriately determined according to the particle size of the light diffusing agent used, but is usually 0.1.
It is about 30 to 30% by weight, preferably about 0.5 to 25% by weight.

In the energy ray-curable resin composition of the present invention, for example, when it is necessary to maintain the hardness of an ultraviolet-cured film and suppress curling, a bifunctional to tetrafunctional (meth) may be used, if necessary.
It may contain an acrylic monomer. Examples of the bifunctional (meth) acrylic monomer include neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, tripropylene di (meth) acrylate, polyethylene glycol di (meth) acrylate, and the like. can give. Trifunctional (meta)
Examples of the acrylic monomer include trifunctional (meth) acrylate. Specific examples thereof include trimethylolpropane (meth) triacrylate and pentaerythritol (meth) triacrylate. Examples of the tetrafunctional (meth) acrylic monomer include pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, and the like. 2 to 4 functional (meta)
The content ratio of the acrylic monomer in the resin composition is 15 to
It is preferably 25% by weight, particularly preferably 20 to 25% by weight.

The energy ray-curable resin composition of the present invention may contain a photopolymerization initiator, if necessary, for example, in order to make the resin curable by ultraviolet rays. Examples of the photopolymerization initiator include 2-hydroxy-2-methylpropiophenone and 4-isopropyl-2-hydroxy-2-
Methyl propiophenone, benzyl dimethyl ketal,
1-hydroxycyclohexyl phenyl ketone, benzophenone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropanone-1,2,4,6
-Trimethylbenzoyldiphenylphosphine oxide and the like can be mentioned. These photopolymerization initiators can be used in combination with accelerators such as tertiary amines. The content ratio of the photopolymerization initiator in the resin composition is preferably 0.5 to 10% by weight, more preferably 2 to 7% by weight.

In order to produce the energy ray-curable resin composition of the present invention, for example, each of the above components may be mixed (dissolved or dispersed) by using a solvent if necessary. Examples of the solvent include toluene, methyl ethyl ketone, ethyl acetate, isopropyl alcohol and the like. The energy ray-curable resin composition of the present invention has a non-reactive compound (for example, an acrylic polymer, a styrene polymer, etc.), an antifoaming agent, and a leveling agent in order to further improve the performance, so long as the original characteristics are not changed. Agent, antistatic agent, flame retardant, antioxidant, light stabilizer, ultraviolet absorber, coupling agent,
It is possible to optimize by including a polymerization inhibitor or the like.

The triacetyl cellulose film of the present invention comprises a cured film layer of the above energy ray curable resin composition,
It has at least one side thereof. This cured film layer is called a hard coat layer when there is no light diffusing material in the composition, and is called a non-glare layer when there is a light diffusing material in the composition. To obtain the triacetyl cellulose film of the present invention having this cured film layer, a micro gravure coater, a gravure coater, a Mayer bar coater,
Using a coating device such as a dip coater, the above energy ray-curable resin composition is applied to the surface of the triacetyl cellulose film so that the thickness after drying is 2 to 7 μm, preferably about 3 to 5 μm. Then, the energy beam may be irradiated. The thickness of the triacetyl cellulose film is preferably about 50 to 200 μm.

The triacetyl cellulose film of the present invention has a large number of thin films of an antireflection layer, for example, a low refractive index fluorine resin, silicon dioxide or a metal compound on the cured film layer of the above energy ray curable resin composition. It is also possible to form a laminated multilayer antireflection film (a fluorine-based resin may be further formed on the multilayer antireflection film). By providing the above-mentioned layer optically designed to reduce the reflected light by the light interference effect, the reflected light scattered on the surface of the hard coat layer or the non-glare layer can be reduced and the transmitted light can be increased. Therefore, when it is used for a display body or the like, this effect is preferable because it makes the display screen clearer and easier to see.

The polarizing plate of the present invention comprises, for example, a triacetylcellulose film having the above-mentioned hard coat layer on one side of the polarizer, and optionally a non-glare layer and an antireflection layer on the other side, and the other side of which is simply a triacetyl cellulose film. It is obtained by pasting and bonding an acetyl cellulose film with an adhesive. Further, the elliptically polarizing plate of the present invention can be obtained by, for example, laminating the above polarizing plate and a retardation plate.

The polarizing plate composed of the triacetyl cellulose film obtained in the present invention does not need to be specially treated with a primer or the like for improving adhesion with a polarizer formed of polyvinyl alcohol. Further, even when the non-glare layer is provided, the decrease in adhesion can be ignored by using the cellulosic resin having a strong affinity for TAC.

The liquid crystal display device of the present invention can be obtained, for example, by disposing the above polarizing plate or elliptically polarizing plate on the front surface of the display body. The screen of this liquid crystal display device has excellent scratch resistance and further has a function of preventing reflection of external light.

[0021]

EXAMPLES The present invention will be specifically described with reference to examples and comparative examples, but the present invention is not limited to these examples. In the examples and comparative examples, “part” means “part by weight”.

Example 1 On a triacetyl cellulose having a thickness of 80 μm, 3.5 g / m ² in dry conversion was applied by a dip coating method at a coating speed of 2 m / min, and the solvent was evaporated. The hard coat layer was formed by irradiating and curing with ultraviolet rays using a high pressure mercury lamp of 80 W / cm to obtain the triacetyl cellulose film of the present invention, and the pencil hardness of the hard coat layer was measured. Further, an adhesive layer provided on the triacetyl cellulose surface of the film of the present invention and laminated on a glass plate was evaluated for adhesiveness under the heat and humidity condition of 80 ° C.-90% RH. The pencil hardness was evaluated according to JIS K5400. The adhesion was evaluated based on JIS K5400 cross-cut tape method (clearance interval 1 mm), and the adhesion was determined after a certain period of time. The results are shown in Table 1. (Clear hard coat resin composition) -Dipentaerythritol hexaacrylate 53 parts-Trimethylolpropane triacrylate 25 parts-Tetrahydrofurfuryl acrylate 22 parts-Ethyl hydroxyethyl cellulose 4.0 parts-Photopolymerization initiator 5.0 parts-Toluene 120 copies

Example 2 Example 1 was repeated, except that the resin composition of Example 1 was added with 7.5 parts of hydrophobically treated silica (average particle diameter of 1.5 μm by Coulter counter method) excluding the solvent. The non-glare layer was formed on the triacetyl cellulose film to obtain the triacetyl cellulose film of the present invention, and the pencil hardness of the hard coat layer was measured.
Further, an adhesive layer provided on the triacetyl cellulose surface of the film of the present invention and laminated on a glass plate was used at 80 ° C-9.
The adhesiveness under the humid heat condition of 0% RH was evaluated. The results are shown in Table 1.

Comparative Example 1 The procedure of Example 1 was repeated except that the ethyl hydroxyethyl cellulose in the resin composition of Example 1 was omitted. The results are shown in Table 1.

Comparative Example 2 The procedure of Example 2 was repeated except that the amount of ethyl hydroxyethyl cellulose in the resin composition of Example 2 was changed to 1.0 part by weight. The results are shown in Table 1.

[0026]

[Table 1] Table 1 Example 1 Example 2 Comparative Example 1 Comparative Example 2 Pencil hardness 3H 3H 3H 3H Adhesion 100 hours 100/100 100/100 0/100 100/100 Over 250 hours 100/100 100/100 − 0/100 hour 500 hours 100/100 100/100 − − interval 750 hours 100/100 100/100 − −

[0027]

EFFECT OF THE INVENTION The energy ray-curable resin composition of the present invention can greatly improve the adhesion to the triacetyl cellulose film as the support without lowering the hard coat property, and durability etc. The reliability of can be greatly improved.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C09D 4/02 PDR C09D 4/02 PDR G02B 1/10 G02B 5/30 5/30 G03F 7/004 511 G03F 7/004 511 7/027 502 7/027 502 G02B 1/10 Z // C08K 3:36

Claims (13)

[Claims] 1. An energy ray-curable resin composition containing 2 to 10 parts by weight of a cellulosic resin with respect to 100 parts by weight of an energy ray-curable resin containing a monomer having 5 or more functional groups. 2. The content of the monomer having 5 or more functional groups in the energy ray-curable resin composition excluding the solvent is 40 to 40.
The energy ray-curable resin composition according to claim 1, which is 60% by weight. 3. The energy ray-curable resin composition according to claim 1, wherein the monomer having 5 or more functional groups is an acrylic monomer. 4. The energy ray-curable resin composition according to any one of claims 1 to 3, which contains a monofunctional (meth) acrylic monomer. 5. The content of the monofunctional (meth) acrylic monomer in the energy ray-curable resin composition excluding the solvent is 5 to 5.
The energy ray-curable resin composition according to claim 4, which is 30% by weight. 6. The energy ray-curable resin composition according to any one of claims 1 to 5, which contains a light diffusing material. 7. The energy ray-curable resin composition according to claim 6, wherein the light diffusing material is silica particles or organic polymer particles. 8. The energy ray-curable resin composition according to claim 6, wherein the content of the light diffusing material in the energy ray-curable resin composition excluding the solvent is 0.1 to 30% by weight. 9. A triacetyl cellulose film having a cured film layer of the energy ray-curable resin composition according to claim 1. Description: 10. The triacetyl cellulose film according to claim 9, wherein an antireflection layer is provided on the cured film layer. 11. A polarizing plate having the triacetylcellulose film layer according to claim 9 or 10. 12. The polarizing plate according to claim 11, wherein the polarizing plate is an elliptically polarizing plate. 13. A liquid crystal display device comprising the film according to claim 9 or 10.