JPH05107149A - Separator for optical inspection - Google Patents

Abstract

PURPOSE:To accurately inspect the quality of an optical blank material while a separator is stuck to the blank material by processing a plastic film with a release agent and making the retardation value of the film equal to or lower than a specific value. CONSTITUTION:It is preferable to form this separator 1 for optical inspection in such a way that a plastic film of a polyester resin is processed with a silicon release agent and the retardation value of the film is set at, for example, <=30nm. The separator 1 can be preferably applied to an adhesive layer 2 attached to an optical blank material 3 for making a polarizing plate, phase difference plate, etc., and it is preferable to use an acrylic adhesive compound having excellent workability to the adhesive layer 2 to which the separator 1 is stuck for protection. When such separator 1 is used, the quality of the optical blank material can be accurately inspected without causing any defective state, such as discoloration, coloring, interference fringes, etc., while the separator 1 is stuck to the blank material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical inspection separator which can be used for quality inspection under the protection of an adhesive layer attached to an optical material such as a polarizing plate.

[0002]

2. Description of the Related Art Optical materials such as polarizing plates and retardation plates are usually provided on the market in the form of being provided with an adhesive layer so that they can be adhered to a supporting base material such as a liquid crystal cell. In that case, the adhesive layer is provided while being protected by the separator.

Conventionally, as the separator, a biaxially stretched polyester film treated with a silicone-based release agent has been known. However, when inspecting an optical material, it is necessary to peel off the separator and then re-bond it after the inspection, which causes a problem that it takes a lot of time for the inspection work.

That is, for example, when the polarizing plates are arranged in a crossed Nicol state while the separator is adhered and the qualities such as the dyeing state and the appearance are inspected, the polarizing plates are normal, but the missing colors, the coloring, the interference fringes, etc. Since a defective state appeared and an accurate inspection could not be performed, it was necessary to remove the separator once.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to obtain a separator which can perform accurate quality inspection while being adhered to an optical material.

[0006]

The present invention provides a separator for optical inspection, which is obtained by treating a plastic film with a release agent and has a retardation value of 30 nm or less.

[0007]

By using a separator having a retardation value of 30 nm or less, accurate quality inspection of the optical material can be performed with the separator adhered.

[0008]

EXAMPLE The separator for optical inspection of the present invention is obtained by treating a plastic film with a release agent and has a retardation value of 30 nm or less, preferably 10 nm or less. The retardation value, that is, the phase difference defined by the product of the refractive index difference of birefringent light and the thickness of the separator is 30 nm.
If it exceeds, it may cause a defective state such as color loss, coloration, or interference fringes, which hinders accurate quality inspection.

The separator for optical inspection can be formed by, for example, a method of forming a plastic film by a method such as a casting method in which optical distortion is unlikely to occur and coating the plastic film with an appropriate release agent.

As a plastic film, transparency,
Those having excellent smoothness and mechanical strength are preferably used. Generally, polyester resin, polyether sulfone resin, polyamide resin, polyimide resin,
A film made of a polycarbonate resin, a polyolefin resin, an acrylic resin, an acetate resin, or the like is used. The thickness of the film is usually 10 to 500 μm, especially 50 to 300 μm, but is not limited thereto.

As the release agent, an appropriate release agent such as silicone type or long chain alkyl type may be used without any particular limitation. Generally, silicone release agents are preferably used. The coating thickness of the release agent may be appropriately determined,
Generally, it is 10 μm or less, preferably 1 to 5 μm.

The optical inspection separator of the present invention is adhered to a liquid crystal cell to form, for example, a liquid crystal display device, such as a polarizing plate, a retardation plate, or an elliptical polarizing plate formed by laminating a polarizing plate and a retardation plate. It can be preferably applied to an adhesive layer attached to an optical material or the like. FIG. 1 illustrates the applied state. Reference numeral 1 is an optical inspection separator. Note that 2 is an adhesive layer and 3 is an optical material.

Incidentally, as the polarizing plate, for example, a film made of a hydrophilic polymer such as polyvinyl alcohol treated with a dichroic dye such as iodine and stretched, or a plastic film such as polyvinyl chloride is treated. Examples thereof include a polarizing film formed by orienting polyene and the like, or a polarizing film protected by a glass plate or a resin film.

Examples of the retardation plate include general-purpose resins such as polycarbonate, polyvinyl alcohol, cellulose acetate, polyester, polyarylate, polyimide and polyolefin, polystyrene and styrene copolymers,
A birefringent film made of polymethylmethacrylate, methylmethacrylate-based copolymer or the like can be used.

There is no particular limitation on the pressure-sensitive adhesive layer that is attached to the optical material and is therefore the object of adhesion and protection of the optical inspection separator. It is preferable to use a pressure-sensitive adhesive that is excellent in workability and durability such as an acrylic pressure-sensitive adhesive.

Example 1 A methylene chloride solution of polycarbonate was uniformly applied on a mirror-finished stainless steel plate with an applicator, dried at 50 ° C. for 5 minutes, and then peeled off from the stainless steel plate. 50μ after dried for 10 minutes
A film of m was formed and coated with a silicone-based release agent to obtain a separator for optical inspection.

Comparative Example A separator was obtained in the same manner as in Example 1 except that a 38 μm thick biaxially stretched polyester film was used in place of the polycarbonate film.

Evaluation Test Retardation Value Wavelength 633 was applied to the separators obtained in Example 1 and Comparative Example.
The retardation value when the light of nm is vertically incident was investigated.

Light transmittance A polarizing plate formed by adhering and protecting an iodine / polyvinyl alcohol type polarizing film having a thickness of 30 μm with a triacetyl cellulose film having a thickness of 80 μm is provided with an acrylic adhesive layer having a thickness of 10 μm, The light transmittance (single transmittance) was examined by adhering the separators obtained in Example 1 and Comparative Example to the adhesive layer. Further, a polarizing plate was arranged in crossed Nicols with respect to the test piece through the separator, and the light transmittance (orthogonal transmittance) thereof was examined. The polarizing plate used was formed according to the above except that the adhesive layer and the separator were not provided. The simple substance transmittance and the orthogonal transmittance in the state where no separator was present (blank) were also examined.

Inspection of Dyeing State In the crossed Nicols state in the above-mentioned light transmittance measurement, the dyeing state of the polarizing plate was visually inspected to examine whether or not an accurate judgment can be made.

The above results are shown in Table 1.

[Table 1]

[0022]

According to the optical inspection separator of the present invention, since a defective state such as color loss or coloring or interference fringes due to the interposition of the separator is not formed, the accurate quality of the optical material can be maintained while the separator is adhered to the optical material. An inspection can be done. Therefore, it is not necessary to remove the separator for the inspection, and the quality inspection of the performance and appearance of the optical material can be efficiently performed.

[Brief description of drawings]

FIG. 1 is an explanatory cross-sectional view of an applied state of a separator.

[Explanation of symbols]

1: Separator for optical inspection 2: Adhesive layer 3: Optical material

Claims (1)

[Claims] 1. A separator for optical inspection, which is obtained by treating a plastic film with a release agent and has a retardation value of 30 nm or less.