JPH0863101A - Bar code label - Google Patents

Abstract

PURPOSE: To improve heat resistance and a black and white contrast by using a specific polyimide film. CONSTITUTION: Polyimide of which the light transmittance at a wavelength 500nm is >=80% is adequate as the polyimide to be used for the polyimide film when made into a film of a thickness of 20μm. An example thereof is the polyimide having the repeating unit expressed by formula I. X is a quadrivalent org. group and includes, for example, the groups expressed by formula II. The polyimide having particularly a hexafluloroisopropylidene in these groups is excellent in light transmissivity and is adequate. Such polyimide is the polyimide having the repeating unit expressed by formula III. The polyimide film may be a polyimide alone, a polyimide copolymer or a polyimide mixture. The thickness of the polyimide film is determined according to the applications of a bar code label to be used and is adequately from about 10 to 150μm.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to bar code labels. In particular, it relates to a bar code label based on polyimide.

[0002]

2. Description of the Related Art Bar code labels are used in many places for purposes such as management of goods and products. For example, supermarkets, convenience stores, etc. have introduced POS systems for the purpose of inventory management and grasp of top-selling products, but each product has a bar code printed or a bar code label attached. ing. There are no special requirements for bar code labels used in such household products, and it suffices if the black and white contrast between the bar code and its base material matches the requirements of the bar code reader. . Therefore, it is sufficient to use a bar code printed on a plastic film or a bar code printed on paper. Recently, the use of bar code labels not only for the management of household products but also for the management of the manufacturing process of various products has gradually come to be used. The purpose is to understand what kind of material parts are used in a certain product and to what extent, for example, by enforcing the Product Liability Law (PL Law), and when recycling various parts. This is because it is necessary to clarify the features of. When using bar code labels for such various parts, unlike household products, they are exposed to various environments. The most severe environmental condition among them is heat.
For example, in the manufacturing process of a printed circuit board, a liquid crystal panel, etc., heat of about 300 ° C. or higher is applied to form electric wiring and electrodes. In such a case, the bar code label conventionally used in household products cannot be used. As an alternative to this, a bar code label using glass as a substrate is manufactured, but it has drawbacks such as being fragile and heavy. On the other hand, barcode labels using polyimide, which is a heat-resistant plastic, have been commercialized. However, the conventional bar code label using polyimide has a drawback that the contrast between white and black is poor because the polyimide itself is colored brown.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a bar code label which is excellent in heat resistance and has a good contrast between black and white.

[0004]

The present invention will be summarized as follows. The present invention relates to a bar code label, and is a polyimide film represented by the following formula (Formula 1):

[0005]

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A polyimide film containing a polyimide having a repeating unit represented by the formula (where X is a tetravalent organic group) is used.

As a result of intensive studies on the bar code label which solves the above problems, the present inventors have found that the problems can be solved by using a specific polyimide film, and have completed the present invention.

[0008] Commercially available polyimide films have a brown color peculiar to polyimide and have poor light transmission in the visible light region. The light transmittance of these films at a thickness of 20 μm is several tens% or less at a wavelength of 500 nm, and the black and white contrast of the bar code label produced using them is poor. When the polyimide film used for the barcode label of the present invention has a light transmittance of 80% or more at a wavelength of 500 nm at a thickness of 20 μm, the produced barcode label has good contrast between black and white. The polyimide used in the polyimide film of the present invention has a thickness of 20 μm.
In the case of using the above film, it is preferable that the light transmittance at a wavelength of 500 nm is 80% or more. An example thereof is a polyimide having a repeating unit represented by the above formula (Formula 1). Here, X is a tetravalent organic group, for example, one represented by the following formula (Formula 3).

[0009]

[Chemical 3]

Of these, a polyimide having a hexafluoroisopropylidene group is particularly preferable because it has excellent light transmittance. This polyimide has the following formula (Formula 2):

[0011]

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A polyimide having a repeating unit represented by: The polyimide film used in the present invention may be a single polyimide, a polyimide copolymer, or a polyimide mixture. Further, if necessary, other additives such as a release agent may be blended.

The thickness of the polyimide film of the present invention can be determined depending on the application of the bar code label used. Usually, considering the manufacturability of polyimide film, 1
About 0 μm to 150 μm is preferable.

The bar code label of the present invention is manufactured by printing a bar code on the above-mentioned polyimide film using a printer or an ink ribbon. If necessary, an adhesive may be applied to the barcode label, or a double-sided tape or the like may be attached.

[0015]

The present invention will be described in detail with reference to the following examples. The present invention is not limited to these examples.

Example 1 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride and 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl and N,
Concentration 15 wt% from N-dimethylacetamide, viscosity 5
A 00 poise polyamic acid solution was obtained. This polyamic acid solution is used to form a film having a thickness of 20 using a polyimide film forming apparatus.
A polyimide film having a thickness of 100 μm and a thickness of 100 μm was obtained. Wavelength 500 of the obtained polyimide film having a thickness of 20 μm
When the light transmittance in nm was measured, the light transmittance was 89%. On the other hand, a barcode was printed on a polyimide film having a thickness of 100 μm using a printer to produce a barcode label. When this bar code label was attached on white paper and the contrast between white and black was compared with the bar code label of a commercially available PET film, it was almost the same. Further, the bar code label of the present invention was left in a constant temperature bath at 300 ° C. for 1 hour, but there was no change in appearance.
On the other hand, the bar code label of the commercially available PET film could not retain the form as a film. Further, the bar code label of the present invention is flexible and did not break when dropped. Barcode labels made of glass, on the other hand, broke when dropped on the floor.

Example 2 Pyromellitic dianhydride, 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl and N, N
-Concentration 15 wt% from dimethylacetamide, viscosity 50
A 0 poise polyamic acid solution was obtained. This polyamic acid solution is applied to a polyimide film forming apparatus to have a thickness of 20 μm.
A polyimide film having a thickness of m and a thickness of 100 μm was obtained. The wavelength of the obtained polyimide film having a thickness of 20 μm is 500 n
When the light transmittance at m was measured, the light transmittance was 85%. On the other hand, a barcode was printed on a polyimide film having a thickness of 100 μm using a printer to produce a barcode label. When this bar code label was attached on white paper and the contrast between white and black was compared with the bar code label of a commercially available PET film, it was almost the same.
Further, the bar code label of the present invention was left in a constant temperature bath at 300 ° C. for 1 hour, but there was no change in appearance. Further, the bar code label of the present invention is flexible and did not break when dropped.

Comparative Example 1 A polyamic acid solution having a concentration of 15 wt% and a viscosity of 500 poise was obtained from pyromellitic dianhydride, 4,4'-diaminodiphenyl ether and N, N-dimethylacetamide. A polyimide film having a thickness of 20 μm and a thickness of 100 μm was obtained from this polyamic acid solution using a polyimide film forming apparatus. When the light transmittance of the obtained 20 μm-thick polyimide film at a wavelength of 500 nm was measured, the light transmittance was 70%. On the other hand, a barcode was printed on a polyimide film having a thickness of 100 μm using a printer to produce a barcode label. When this bar code label was attached on white paper and the contrast between white and black was compared with the bar code label of a commercially available PET film, it was clearly inferior.

[0019]

The bar code label of the present invention has heat resistance that plastic bar code labels have never had.
It has flexibility and impact resistance not available in conventional glass products, and black / white contrast properties not available in conventional polyimide products, making it suitable for controlling the manufacturing process of liquid crystal panels, printed circuit boards, automobile engines, etc. There are advantages that can be used.

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Claims (2)

[Claims] 1. A polyimide film having the following formula (Formula 1): A bar code label comprising a polyimide film containing a polyimide having a repeating unit represented by (where X is a tetravalent organic group). 2. A polyimide film having the following formula (Formula 2): A bar code label comprising a polyimide film containing a polyimide having a repeating unit represented by.