JP2013155219A - Hard coat film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hard coat film used inside the touch panel of computers, portable devices or the like, having excellent adhesiveness in sticking by a double-sided adhesive tape, and having a hard coat layer hardly peeling from the double-sided adhesive tape.SOLUTION: In a hard coat film, a hard coat layer containing at least one of pentaerythritol triacrylate and pentaerythritol tetraacrylate is formed on one side of a translucent base substance, and the contact angle of the hard coat layer with water is 70° or less.

Description

  The present invention relates to a hard coat film used inside a touch panel of a computer or a portable device, and more specifically, a hard coat excellent in adhesiveness with a pressure-sensitive adhesive having a hard coat layer on a translucent substrate such as a plastic film. It relates to film.

  In recent years, touch sensors have begun to be mounted on portable devices. Touch sensors for mobile devices are mainly equipped with a resistive touch panel that detects the pressure at the time of input and a capacitive touch panel that detects the input location by static electricity from the human body at the time of input. In view of the multi-functionality of the input method, the capacitive method is becoming mainstream.

  FIG. 1 is a cross section of a capacitive touch panel in a general portable device. In FIG. 1, a sensor component is formed under the protective panel 1 via an optical adhesive layer 2. The sensor component has a transparent conductive film 3 and a transparent conductive film 5 on both surfaces of a transparent film 4 such as a PET film. The transparent conductive film 3 and the transparent conductive film 5 are patterned, and the transparent film 4 is an insulating material. In this case, the input position is detected by a change in capacitance caused by contact with a finger or the like.

A transparent substrate 7 is attached to the transparent conductive film 5 with an optical adhesive layer 6 for the purpose of protecting the surface of the transparent conductive film 5. This translucent substrate 7 also has the purpose of preventing oxidation of the transparent conductive film and internal wiring due to humidity. In addition, a hard coat layer 8 is formed on the back surface of the translucent substrate 7 in order to prevent scratches during manufacturing and scratches caused by rubbing against the LCD surface after being set in a product.
Further, the liquid crystal panel module 10 is attached to the surface of the hard coat layer 8 with a frame-like double-sided adhesive tape 9 or attached to the entire surface of the hard coat layer 8 with the double-sided adhesive tape 9 to constitute a portable device. doing.

JP 2003-122503 A

Conventionally, acrylic resin or siloxane resin has been used as the hard coat layer 8. However, such a conventional hard coat layer has a problem of poor adhesion with the double-sided pressure-sensitive adhesive tape 9 and easily peels off due to vibration or the like.
The present invention has been made in view of the above problems, and has a hard coat layer 8 that has excellent adhesion to the double-sided pressure-sensitive adhesive tape 9 and does not easily peel from the double-sided pressure-sensitive adhesive tape 9. The object is to provide a film.

  The hard coat film of the present invention is a hard coat film in which a hard coat layer containing at least one of pentaerythritol triacrylate and pentaerythritol tetraacrylate is formed on one surface of a translucent substrate, The contact angle of the layer with water is 70 degrees or less.

  Moreover, it is preferable that the ratio of pentaerythritol tetraacrylate is 50 mass%-100 mass% in the total amount of the pentaerythritol triacrylate and pentaerythritol tetraacrylate in the said hard-coat layer.

  According to the hard coat film of the present invention, it is a hard coat film used inside a touch panel such as a computer or a portable device, and has excellent adhesion with a double-sided pressure-sensitive adhesive tape for attaching a liquid crystal panel module, A hard coat film having a hard coat layer that does not easily peel from the double-sided pressure-sensitive adhesive tape can be provided.

It is sectional drawing of the capacitive touch panel in a portable device.

Next, an embodiment of the hard coat film of the present invention will be specifically described.
The hard coat film of the present invention is one in which a hard coat layer is formed on one surface of a translucent substrate.
Hereinafter, these components will be described in detail.

1. Translucent substrate As the translucent substrate used in the present invention, polyethylene terephthalate (PET), triacetyl cellulose (TAC), polyethylene naphthalate (PEN), polymethyl methacrylate (PMMA), polycarbonate (PC), polyimide (PI), polyethylene (PE), polypropylene (PP), polyvinyl alcohol (PVA), polyvinyl chloride (PVC), cycloolefin copolymer (COC), norbornene-containing resin, polyethersulfone, cellophane, aromatic polyamide, etc. A resin film can be suitably used.

  The higher the transparency of these translucent substrates, the better. However, the light transmittance (JIS K7361-1) is preferably 80% or more, more preferably 90% or more. Further, the thickness of the translucent substrate is preferably thin from the viewpoint of weight reduction, but considering handling properties, it is preferable to use a substrate having a thickness in the range of 1 μm to 700 μm, preferably 25 μm to 250 μm. is there.

  In the present invention, an adhesive layer may be provided between the translucent substrate and the hard coat layer in order to sufficiently bond the translucent substrate and the hard coat layer. As the easy adhesion layer, a polyester resin, an epoxy resin, an alkyd resin, an acrylic resin, a urea resin, a urethane resin, or the like can be suitably used. In particular, it is more preferable to use a resin selected from a polyester resin, an acrylic resin, and a urethane resin from the viewpoint of adhesiveness. A polyester resin and an acrylic resin, a polyester resin and a urethane resin, or a combination of an acrylic resin and a urethane resin may be used. Good.

  In particular, a polyester resin is more preferable. For example, when the translucent substrate is a PET film, the refractive index is about 1.65. The easy-adhesion layer formed thereon has a value close to the refractive index of the PET film, so that the difference in refractive index between the easy-adhesion layer and the PET film can be reduced, and the optical characteristics can be improved. It is. Moreover, the thickness of an easily bonding layer becomes like this. Preferably they are 20 nm or more and 200 nm or less, More preferably, they are 50 nm or more and 150 nm or less.

2. Hard coat layer The hard coat layer in the present invention contains at least one of pentaerythritol triacrylate and pentaerythritol tetraacrylate.
The double-sided pressure-sensitive adhesive tape used inside the touch panel has a ratio of pentaerythritol tetraacrylate of 50% by mass to 100% by mass in the total amount of pentaerythritol triacrylate and pentaerythritol tetraacrylate in the hard coat layer; Is preferable because of good adhesion.
The hard coat layer must have a contact angle with water of 70 degrees or less. When the contact angle with water is larger than 70 degrees, the adhesiveness with the double-sided pressure-sensitive adhesive tape used inside the touch panel is poor and it peels easily.

  The hard coat layer may be composed entirely of at least one of pentaerythritol triacrylate and pentaerythritol tetraacrylate, but may contain a resin other than pentaerythritol triacrylate and pentaerythritol tetraacrylate. The resin other than pentaerythritol triacrylate and pentaerythritol tetraacrylate is preferably 40% by mass or less, more preferably 20% by mass or less, based on the total amount of the hard coat layer.

  As the resin other than pentaerythritol triacrylate and pentaerythritol tetraacrylate, an acrylic acrylate resin having an acryloyl group and / or a methacryloyl group is preferable. As monomer components constituting the acrylic acrylate resin, ethyl (meth) acrylate, ethylhexyl ( Monofunctional monomers such as (meth) acrylate, styrene, methylstyrene, N-vinylprolidone and polyfunctional monomers such as trimethylolpropane (meth) acrylate, hexanediol (meth) acrylate, tripropylene glycol di (meth) acrylate, Diethylene glycol (meth) acrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, dipentaeryth Toruhekisa (meth) acrylate, 1,6-hexanediol di (meth) acrylate, and neopentyl glycol (meth) acrylate.

  The hard coat layer preferably contains a photopolymerization initiator. Examples of the photopolymerization initiator include radical polymerization initiators such as acetophenone, benzophenone, thioxanthone, benzoin, and benzoin methyl ether, and cationic polymerization such as aromatic diazonium salts, aromatic sulfonium salts, aromatic iodonium salts, and metallocene compounds. Initiators can be used alone or in appropriate combination.

If necessary, pigments, dyes, fillers, plasticizers, ultraviolet absorbers, antioxidants, thixotropic agents, and the like may be added to the hard coat layer forming material as long as the performance is not impaired. These additives may be used alone or in combination of two or more.
However, the hard coat layer of the present invention is most preferably one obtained by drying and curing a paint in which at least one of pentaerythritol triacrylate and pentaerythritol tetraacrylate, an organic solvent, and a photopolymerization initiator are mixed.

5. Method for Producing Hard Coat Film The hard coat film of the present invention is produced, for example, by applying a hard coat paint containing an organic solvent on a translucent substrate, drying and then curing. As a method for applying the paint on the translucent substrate, a normal coating method or printing method is applied. Specifically, air doctor coating, bar coating, blade coating, knife coating, reverse coating, transfer roll coating, gravure roll coating, kiss coating, cast coating, spray coating, slot orifice coating, calendar coating, dam coating, dip coating Coating such as die coating, intaglio printing such as gravure printing, printing such as stencil printing such as screen printing, and the like can be used.

Next, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.
1. Manufacture of hard coat film

<Example 1>
The raw material which consists of the following mixing | blending is mixed, and it becomes a layer thickness of 6 micrometers after drying on the translucent base material made from a polyethylene terephthalate (brand name: U48K, the Toray company make, thickness: 125 micrometers, the surface is equipped with an easily bonding layer) A hard coat layer was applied as described above. Next, the hard coat layer was dried at 80 ° C. for 1 minute and then cured by irradiation with a high-pressure mercury lamp corresponding to an energy of 350 mJ / cm ^{2 in} an air atmosphere to obtain a hard coat film of the present invention.
[Combination]
Pentaerythritol tetraacrylate 100 parts by weight Methyl isobutyl ketone 100 parts by weight Photopolymerization initiator (trade name: Irgacure 184, manufactured by Ciba Japan) 1.8 parts by weight

<Example 2>
A hard coat film of the present invention was obtained in the same manner as in Example 1 except that raw materials having the following composition were mixed and used as the hard coat layer.
[Combination]
Pentaerythritol tetraacrylate 75 parts by weight Pentaerythritol triacrylate 25 parts by weight 100 parts by weight of methyl isobutyl ketone Photopolymerization initiator (trade name: Irgacure 184, manufactured by Ciba Japan) 1.8 parts by weight

<Example 3>
A hard coat film of the present invention was obtained in the same manner as in Example 1 except that raw materials having the following composition were mixed and used as the hard coat layer.
[Combination]
Pentaerythritol triacrylate 50 parts by weight Pentaerythritol tetraacrylate 50 parts by weight Methyl isobutyl ketone 100 parts by weight Photopolymerization initiator (trade name: Irgacure 184, manufactured by Ciba Japan) 1.8 parts by weight

<Example 4>
A hard coat film of the present invention was obtained in the same manner as in Example 1 except that raw materials having the following composition were mixed and used as the hard coat layer.
[Combination]
Pentaerythritol tetraacrylate 25 parts by weight Pentaerythritol triacrylate 75 parts by weight Methyl isobutyl ketone 100 parts by weight Photopolymerization initiator (trade name: Irgacure 184, manufactured by Ciba Japan) 1.8 parts by weight

<Example 5>
A hard coat film of the present invention was obtained in the same manner as in Example 1 except that raw materials having the following composition were mixed and used as the hard coat layer.
[Combination]
Pentaerythritol triacrylate 100 parts by weight Methyl isobutyl ketone 100 parts by weight Photopolymerization initiator (trade name: Irgacure 184, manufactured by Ciba Japan) 1.8 parts by weight

<Comparative Example 1>
A comparative hard coat film was obtained in the same manner as in Example 1 except that raw materials having the following composition were mixed and used as the hard coat layer.
[Combination]
-100 parts by weight of ditrimethylolpropane tetraacrylate-100 parts by weight of methyl isobutyl ketone-Photopolymerization initiator (trade name: Irgacure 184, manufactured by Ciba Japan) 1.8 parts by weight

<Comparative example 2>
A comparative hard coat film was obtained in the same manner as in Example 1 except that raw materials having the following composition were mixed and used as the hard coat layer.
[Combination]
・ Dipentaerythritol hexaacrylate 100 parts by mass ・ Methyl isobutyl ketone 100 parts by mass ・ Photopolymerization initiator (trade name: Irgacure 184, manufactured by Ciba Japan) 1.8 parts by mass

2. Contact angle with water of hard coat layer The contact angle with water of the hard coat layer in the hard coat films of Examples 1 to 5 and Comparative Examples 1 and 2 is measured by a measuring device (Model made by ERMA INC.) By the θ / 2 method. It was measured using G-1). The measurement was performed in a drop volume of 5 microliters, at room temperature of 23 ° C., and 50% RH.
The measurement results are shown in Table 1.

3. Evaluation of Hard Coat Film The peel strength of the hard coat layer in the hard coat films of Examples 1 to 5 and Comparative Examples 1 and 2 was measured based on JIS-Z0237. As the double-sided pressure-sensitive adhesive tape, Sekisui Chemical Co., Ltd. product name 5220 using an acrylic pressure-sensitive adhesive was used.
The measurement results are shown in Table 2.

As shown in Table 2, the hard coat films in Examples 1 to 5 of the present invention have a peel strength from the double-sided pressure-sensitive adhesive tape of 2.01 kg / 25 mm or more in any double-sided pressure-sensitive adhesive tape. It was confirmed that the adhesiveness was superior to that of the above. In particular, Examples 1 to 3 in which the proportion of pentaerythritol tetraacrylate is 50% by mass to 100% by mass have a peeling force with the double-sided pressure-sensitive adhesive tape more than Examples 4 and 5 in which the proportion of pentaerythritol tetraacrylate is less than 50% by mass. It was excellent.
On the other hand, Comparative Examples 1 and 2 of the hard coat layer not containing at least one of pentaerythritol triacrylate and pentaerythritol tetraacrylate had a low peeling force and had practical problems.

1 protection panel 2 optical adhesive layer 2
DESCRIPTION OF SYMBOLS 3 Transparent electrically conductive film 4 Transparent film 5 Transparent electrically conductive film 6 Optical adhesive layer 7 Translucent base | substrate 8 Hard-coat layer 9 Double-sided adhesive tape 10 Liquid crystal panel module

Claims (3)

  A hard coat film containing at least one of pentaerythritol triacrylate and pentaerythritol tetraacrylate is formed on one surface of a translucent substrate, and a contact angle of the hard coat layer with water is A hard coat film, which is 70 degrees or less.   2. The hard coat film according to claim 1, wherein a ratio of pentaerythritol tetraacrylate is 50% by mass to 100% by mass in a total amount of pentaerythritol triacrylate and pentaerythritol tetraacrylate in the hard coat layer. .   The hard coat layer is obtained by drying and curing a paint in which at least one of pentaerythritol triacrylate and pentaerythritol tetraacrylate, an organic solvent, and a photopolymerization initiator are mixed. 2. The hard coat film according to 2.

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