JPH0882600A - Measurement of reflectivity of plastic film - Google Patents

Abstract

PURPOSE: To accurately detect the reflectivity of a plastic film during running by closely bonding a black film to the rear surface of the plastic film. CONSTITUTION: The film 2 to be measured delivered from a film delivery machine 1 is closely laminated and bonded to the black film 4 unwound from a separate film unwinder 3 by a laminating roll 5. After the reflectivity of the film 6 to be measured to which the black film 4 is bonded is measured by the reflectivity detector 8 arranged at the part of the measuring roll 7, the film 6 to be measured is taken up by a film winder 9. The black film 4 may be reversely delivered from a separate film winder 9 or may be peeled in front of the film winder 9. As the black film 4, a film prepared by adding black pigment such as carbon black or org. black pigment to plastic of every kind is used. Further, a plastic film of every kind coated with black paint is also used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for accurately measuring the reflectance of an optical plastic film such as an antireflection film while it is running.

[0002]

2. Description of the Related Art In recent years, plastic films having antireflection properties have been used for filter surfaces for OA equipment displays,
It is used to prevent reflection on the surface of liquid crystal displays.
The antireflection film is obtained by forming one having a small refractive index such as magnesium fluoride, silicon oxide, zirconium oxide, and titanium oxide and / or one having a large refractive index as a single-layer thin film or a multi-layer thin film on a plastic film. To be In manufacturing and using an optical plastic film typified by an antireflection film, it is necessary to understand the reflectance as a matter of course. Up to now, the film used as the measurement sample was cut into small pieces and
This reflectance was measured with each of them kept stationary. or,
For more accurate measurement, it is necessary to prevent light reflection on the back side of the measurement surface, and as a method for preventing back reflection of the film, black paint has been applied to the back surface.

[0003]

When a plastic film is manufactured or used, it is common to wind the plastic film or run it. When trying to detect the reflectance of a moving object, the method of cutting out a small sample and measuring the reflectance is not suitable. Further, the method of applying a black paint on the back surface is not realistic because it stains the film to be the product. The present invention provides a method for accurately detecting reflectance while running a plastic film.

[0004]

That is, the present invention provides a method for measuring the reflectance of a running plastic film surface, wherein the plastic film has a black film adhered to its back surface. And a method for measuring the reflectance of a plastic film.

Examples of the plastic film applicable to the present invention include transparent films such as polyester film, polycarbonate film, polymethylmethacrylate film and cellulose acetate film, and various polarizing films used in liquid crystal displays.

As the black film of the present invention, various plastics containing a black pigment such as carbon black or an organic black pigment can be used as a black film. In addition, various plastic films coated with black paint are also used.

In order to bring the black film used in the present invention into close contact with the plastic film, a suitable adhesive force is required. This adhesive force is such that it can be adhered to the plastic film to the extent that air is not present, but it can be easily peeled from the plastic film after the reflectance is measured. Its adhesive strength is film width 25mm
Usually, it is about 3 to 100 g.

To impart tackiness to the black film, a material having self-adhesiveness such as ethylene / vinyl acetate copolymer itself is used, or a material having self-adhesiveness is co-extruded to form a composite film. And applying an adhesive to give adhesiveness.

To adhere the black film to the plastic film, a known method in which both films are pasted between a plurality of laminating rolls and laminated can be applied.

The reflectance of a plastic film is measured by
The ratio of the reflected light to the incident light was obtained using a photometer that measures the amount of light. A commercially available device can be used as the reflectance measuring device.

An example of the reflectance measuring method of the present invention is shown in FIG. The film to be measured 2 fed out from the film feeding device 1 is bonded to the black film 4 wound from another film feeding device 3 by the bonding roll 5. The film to be measured 6 to which the black film is pasted is measured by the reflectivity detector 8 installed at the portion of the measuring roll 7 and then wound on the film winder 9. The black film may be separately fed out from the film winder 9 in reverse and peeled off, or may be peeled off before the film winder 9 in advance. This example illustrates one embodiment of the present invention, and the present invention is not limited to this.

[0012]

EXAMPLES Reflection having a four-layer antireflection film of the kind and thickness (nm) shown in Table 1 on the hardcoat layer side of a polymethylmethacrylate film having a thickness of 250μ having a hardcoat layer having a thickness of 5μ on the surface The prevention films S1 and S2 were used. The reflectance measuring device is MCPD- manufactured by Otsuka Electronics Co., Ltd.
It was 1000, and the spectrum of 400 to 700 nm in the visible light region was measured.

[0013]

[Table 1]

With respect to the roll-shaped films S1 and S2, the reflectance was measured using the measuring system having the same structure as in FIG. 1 while the film was running. First, without using the black film 4, only the films S1 and S2 (blank film) were run and the reflectance was measured. In this case, when the reflectance is measured on the measuring roll 7, the influence of the reflection on the roll surface appears. Therefore, the reflectance detector 8 is installed at an intermediate position between the bonding roll 5 and the free roll 10 to perform the measurement. It was An example of the reflectance spectra of the films S1 and S2 obtained by this method is shown in FIG.

Next, an acrylic adhesive was applied to a black polyethylene film having a thickness of 60 μ (film width 25 mm
Adhesive force per 60 g) The black film 4 was supplied from the film feeding machine 3 and stuck to the films S1 and S2, and the reflectance detector 8 was installed on the measuring roll 7 for measurement. An example of the reflectance spectra of the films S1 and S2 obtained by this method is shown in FIG.

A sample of a small piece was cut out from each of the films S1 and S2, and black paint was applied to the back surface of the sample to measure the reflectance. The reflectance spectra of the films S1 and S2 obtained by this method are shown in FIG.

FIG. 3 of the present invention obtains the reflectance value of the same level as that of FIG. 4, and FIG. 2 is affected by the back surface reflection, so that it is far more than the values of FIGS. 3 and 4. big,
It can be seen that this method cannot quantitatively capture the antireflection property.

[0018]

According to the present invention, the reflectance of a running plastic film can be accurately measured by sticking a black adhesive film on the back surface of the plastic film. This makes it possible to easily manufacture an antireflection film having a uniform reflectance.

[Brief description of drawings]

FIG. 1 is a schematic view of a method for measuring reflectance according to the present invention.

FIG. 2 is a reflectance spectrum diagram of a blank film.

FIG. 3 is a reflectance spectrum diagram of the film of the present invention.

FIG. 4 is a reflectance spectrum diagram of a black coating film.

[Explanation of symbols]

 1: Film unwinder 2: Film to be measured 3: Film unwinder 4: Black film 5: Laminating roll 6: Laminated film to be measured 7: Measuring roll 8: Reflectance detector 9: Film winder

Claims (1)

[Claims] 1. A method for measuring the reflectance of a surface of a running plastic film, wherein the plastic film has a black film adhered to its back surface. Measuring method.