JP2001281454A - Optical film with protective film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical film with protective film easily releasable only in the case of using. SOLUTION: The optical film with protective film is provided with an optical film having ruggedness of <=1.5 μm center line average surface roughness (Ra) and <=250 μm average mountain and valley interval (Sm) on the outermost surface and a protective film stuck to the optical film via an adhesive layer whose elastic modulus is <=0.25 Mpa, preferably <=0.20 Mpa and the thickness is 5-40 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical film having a protective film laminated on the surface.

[0002]

2. Description of the Related Art Since optical films such as polarizing plates are used optically, the surface must not be scratched or stained, and can be peelably protected on the surface during processing as well as during inspection. The films are laminated. The protective film is generally made of a plastic such as PET or polyethylene, has a pressure-sensitive adhesive applied to one side, and is laminated on the optical film via the pressure-sensitive adhesive layer.

The properties required for this protective film include:
It does not easily peel off from the optical film against environmental changes such as temperature and humidity or light impact, that the adhesive does not remain on the surface of the optical film when peeled off, that it can be easily peeled off by machine or hand, And the like.

On the other hand, in many optical films, an antiglare layer is provided on the outermost surface to prevent reflection of a light source such as a fluorescent lamp. The antiglare layer generally has irregularities with a center line average roughness (Ra) of 1.5 μm or less and an average peak-to-valley interval of 250 μm or less.

[0005]

Among the necessary properties of the above protective film, depending on the surface properties of the optical film to be protected, when the protective film is laminated, the pressure-sensitive adhesive of the protective film and the surface of the optical film are not adhered to each other. May be easily separated due to a small contact area. This phenomenon is particularly remarkable when the surface of the protected object has a rough surface such as the above anti-glare layer, and there is a problem that the protective film is peeled off from the protected object due to a slight impact even when bonded under a considerable pressure. there were.

In order to solve this problem, generally, means for increasing the thickness of the pressure-sensitive adhesive layer can be considered. However, conversely, even when it is necessary to peel to remove the protective film, manual peeling becomes difficult, and even if it is peeled off by a machine, the adhesive remains on the surface of the protected object. There's a problem. Therefore, an object of the present invention is to provide an optical film with a protective film, in which the protective film has an appropriate adhesion and good releasability.

[0007]

In order to solve the above-mentioned problems, the present invention is directed to a surface shape having a center line average roughness (Ra) of 1.5 μm or less and an average peak-to-valley interval (Sm) of 250 μm or less. An optical film having irregularities on the outermost surface,
A protective film attached to the optical film via an adhesive layer, wherein the adhesive has an elastic modulus of 0.25
An optical film with a protective film, which has a thickness of 5 to 40 μm, which is not more than Mpa, preferably not more than 0.20 Mpa.

When the pressure-sensitive adhesive has the above-mentioned elastic modulus and thickness, the peeling force of the protective film from the optical film is 0.1%.
10 to 0.30 N / 50 mm. As a result, it does not peel off due to a slight impact or the like, and when peeling is necessary, it can be easily peeled off manually. In order for the pressure-sensitive adhesive to have the above-described relationship between the elastic modulus and the thickness, it is preferable to use a copolymer of isononyl acrylate and stearyl acrylate as the main component of the pressure-sensitive adhesive.

[0009]

EXAMPLES-Example 1-100 parts by weight of isononyl acrylate (hereinafter referred to as "weight")
Omit. ), 50 parts of stearyl acrylate, 2 parts of hydroxyethyl acrylate and 0.3 parts of benzoyl peroxide in a toluene solution with stirring at about 60 ° C. to obtain a polymer solution. An isocyanate-based crosslinking agent (Coronate LC manufactured by Nippon Polyurethane Co., Ltd.) was added to the polymer solution in an amount of 3 parts per 100 parts of polymer solids.
By adding one part, an adhesive having an elastic modulus of 0.18 Mpa was produced. Separately, a PET film having a thickness of 35 μm was prepared, and the pressure-sensitive adhesive was dried on one side to a thickness of 10 μm.
A protective film was produced by applying such that

Comparative Example 1 A toluene solution of 100 parts of 2-ethylhexyl acrylate, 75 parts of vinyl acetate, 5 parts of acrylic acid and 0.3 part of benzoyl peroxide was reacted at about 60 ° C. while stirring to form a polymer solution. Obtained. An adhesive having an elastic modulus of 0.41 Mpa was produced by adding 3 parts of an epoxy crosslinking agent (Tetrad C manufactured by Mitsubishi Gas Chemical Co., Ltd.) to 100 parts of the polymer solid content to this polymer solution. A protective film was prepared by applying the pressure-sensitive adhesive to one side of the same PET film as in Example 1 so as to have a thickness of 10 μm.

Comparative Example 2 A protective film was prepared under the same conditions as in Example 1 except that an adhesive was applied so that the thickness after drying was 60 μm. The obtained protective film was treated with a laminator for 0.0
At a pressure of 5 MPa, the center line average roughness (Ra) is 0.8 μm.
The polarizing plate with the anti-glare layer having irregularities of m and average peak-to-valley interval (Sm) of 150 μm on the surface was bonded to the surface. Then, the peeling force, the peelability by manual work, and the adhesion of the laminated film were measured. The peel force was 180 at a speed of 300 mm / min using a tensile tester.
It was measured by peeling in the ° direction. Peelability and adhesion are based on relative evaluation. The measurement results of Example 1, Comparative Example 1 and Comparative Example 2 are shown in Table 1 below.

[0012]

[Table 1] Regarding the adhesion of Comparative Example 1, the end face was easily turned up,
Even when they were attached by a laminator, they did not adhere.

[0013]

The optical film with a protective film according to the present invention is convenient because the protective film has both proper peeling properties and adhesiveness, so that it can be easily peeled off immediately before use without peeling immediately before use.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yuji Kazuki 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation (72) Inventor Tomomori Masada 1-1-1, Shimohozumi, Ibaraki-shi, Osaka No. 2 Nitto Denko F-term (reference) 2H042 BA03 BA13 BA16 2H049 BA02 BB23 BB54 BB62 BB63 4F100 AK42 AR00A AR00B AT00C BA03 BA07 BA10A BA10C DD07A GB90 JA20B JK07B JL11 JL13B JL14 JL30B00

Claims (2)

[Claims] (1) The surface has a center line average roughness (Ra) of 1.
An optical film having an unevenness on the outermost surface of 5 μm or less and an average peak-to-valley interval (Sm) of 250 μm or less; and a protective film bonded to the optical film via an adhesive layer. When the elastic modulus is 0.25Mpa or less and the thickness is 5
An optical film with a protective film, wherein the thickness is from 40 to 40 μm. 2. The optical film with a protective film according to claim 1, wherein the optical film is a polarizing plate with anti-glare or an anti-glare sheet.