JP2757265B2 - Heat resistant barcode label - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a barcode label having excellent heat resistance and dimensional stability.

[Problems to be solved by conventional technology and invention]

In recent years, barcode systems such as POS (Point of Sale) and EOS (Electronic Replenishment Ordering System) for progress management, process management, inventory management and store automation in FA have been used in various fields, Demand for code labels is also growing rapidly.

As a base material of a conventionally used barcode label, first, paper or woven fabric is used. Since these structures are entangled with each other, fine lines are not sharply formed due to ink bleeding or the like, and the surface morphology is not suitable for high-density barcodes. To compensate for these drawbacks, thermoplastic general-purpose films typified by polyester (PET) are used, but these have poor heat resistance, and when used at a high temperature of 150 ° C or more, dimensional changes due to shrinkage are large. Alternatively, it has a drawback that the shape cannot be maintained due to melting.

On the other hand, the pressure-sensitive adhesive which is a main component of the label is, for example, a silicone-based pressure-sensitive adhesive made of polysiloxane, such as maintaining good adhesiveness without thermal deterioration even in a high temperature range of 200 to 450 ° C. There is no problem with heat resistance.

Thus, when using a barcode label in a high temperature range of about 200 to 450 ° C., insufficient heat resistance of the base film has been a problem.

[Means for solving the problem]

The present invention has the following configuration to solve the above problems.

That is, the present invention has a strength of 10 kg / mm ² or more in any direction, and a heat shrinkage rate at 250 ° C. is 0.5% or less.
A heat-resistant bar code label used in a high temperature range of 200 to 450 ° C., which is coated with a silicone-based adhesive made of polysiloxane.

The film used for the heat-resistant barcode label of the present invention is made of a para-oriented aromatic polyamide.

As the para-oriented aromatic polyamide, poly (p-
Most preferred are phenylene terephthalamide) (hereinafter referred to as PPTA), poly (p-benzamide) and small copolymers thereof.

PPTA used as the most preferred polymer in the present invention
Is substantially It is a polymer represented by the following formula, and if it is conventionally known from paraphenylenediamine and terephthaloyl chloride, it is convenient to produce it by a low-temperature solution polymerization method.

If the degree of polymerization of the para-oriented aromatic polyamide of the present invention is too low, a film having good mechanical properties cannot be obtained. Therefore, the logarithmic viscosity η inh of preferably 3.5 or more, more preferably 4.5 or more (polymer in 100 ml of sulfuric acid) Dissolve 0.5 g and 30
(A value measured in ° C.) is selected.

The film made of the para-oriented aromatic polyamide used in the present invention is excellent in heat-resistant dimensional stability, and the heat shrinkage at 250 ° C. is used as a measure of the stability. The heat shrinkage of the film used in the present invention is 0.5% or less, more preferably 0.3% or less. The preferable aspect of the film having a small heat shrinkage ratio is that the original substance of PPTA molecules having high crystallinity, high orientation and rigidity is obtained by a special production method of the film described later, that is, optically anisotropic doping. By a manufacturing method that combines isotropic solidification, biaxial stretching in a wet state, and heat-restriction heat treatment at 300 ° C. or more, a dense, highly oriented and highly crystalline structure leaves no strain. It is believed that the result was more than sufficient because it was formed.

As the film made of the para-oriented aromatic polyamide used in the present invention, a film having a thickness of about 5 μm or more is useful, and a film having a thickness of 15 μm or more is more useful.

The film made of the para-oriented aromatic polyamide used in the present invention preferably has a strength of 10 kg / mm ² or more, more preferably 15 kg / mm ² or more in any direction.

The film used in the present invention is produced, for example, by the following method. That is, an optically anisotropic dope substantially composed of la-oriented aromatic polyamide and 95% by weight or more of sulfuric acid is cast from a die onto a moving supporting surface while maintaining optical anisotropy, and is subjected to moisture absorption // The dope is converted to optically isotropic by heating, coagulated, washed, biaxially stretched in a wet state, dried, and then heat-treated at 300 ° C. or higher while restricting shrinkage. be able to.

Adhesive used in the present invention, rubber, acrylic,
Any of commercially available pressure-sensitive adhesives such as vinyl-based and silicon-based pressure-sensitive adhesives may be used, but when used in a high temperature range of 200 to 450 ° C, a silicon-based pressure-sensitive adhesive made of polysiloxane is preferably used. In some cases, it is also useful to use a commercially available undercoating agent to enhance the adhesion between the film and the pressure-sensitive adhesive, or to modify the surface of the film by various surface treatments such as corona discharge. In addition, regarding the releasability of the film and the pressure-sensitive adhesive, since the surface of the film originally has a high releasability, no special treatment is required. May be used.

The size of the barcode used in the present invention is JI
Although the basic size defined in the S standard is preferable, a high-density barcode in which the size of the thin bar is further reduced to 50 μm as necessary may be used.

As a method for printing a barcode on the film used in the present invention, it is convenient and preferable to use a commercially available printer, for example, a Samar-type barcode printer, a dot-type barcode printer, etc., but there is no particular limitation. Further, in order to eliminate the reading error of the barcode, it is necessary to improve the contrast between the barcode and the base film. Before and / or simultaneously with printing the barcode, the barcode is colored with ink having a high contrast with the barcode color. It is useful to apply the surface of the film beforehand. Further, the above-mentioned various surface modification methods are useful for improving the ink paste of the printer.

〔Example〕

Hereinafter, the present invention will be described with reference to examples. However, the present invention is not limited by the examples.

The heat shrinkage rate shown in the examples was determined by taking a sample of about 10 cm length, measuring the length with a precision microscope at 25 ° C. and 60% RH, placing it in an oven at 250 ° C. for 2 hours, taking it out, and taking out the sample.
The length after being left for 2 hours in an atmosphere of 60 ° C. and 60% RH was measured precisely, and the ratio of the decrease to the initial length of the sample was expressed as a percentage.

Example 1 PPTA having an η inh of 4.6 was dissolved in 99.5% sulfuric acid so as to be 12.5% to obtain a dope having an optical anisotropy of 700 poise at 65 ° C. After deaeration and filtration, the dope was cast on a tantalum belt from a die having a slit of 0.25 mm × 300 mm. At this time, the discharge linear velocity from the die is 1.7m
/ Min, and the belt moving speed was 5 m / min. Relative humidity approx.
The cast dope was converted to a transparent optically isotropic dope by blowing 30% air at about 110 ° C, and then coagulated with a 10% aqueous sulfuric acid solution at 0 ° C. After the coagulated sheet was peeled off from the belt, the sheet was washed with water at room temperature, a 0.2% aqueous solution of caustic soda, and water at about 30 to 40 ° C. in this order.

The obtained wet film was sequentially stretched 1.1 times in the length direction and 1.25 times in the width direction, and then dried and heat-treated for 5 minutes in a tenter in which hot air at 350 ° C. circulates.

The obtained film is transparent, has a thickness of 20 μm, and has a tensile strength of 32.
kg / mm ^2, tensile elastic modulus 1350 kg / mm ^2, density of 1.40kg / cm ^3, 250
The heat shrinkage at 0.0 ° C. was 0.09%.

A white ink is applied to the front of the obtained film, and a silicone-based pressure-sensitive adhesive made of polysiloxane is applied to the back thereof,
Laminated with release paper. A USS-39 type barcode was printed on the laminate using a commercially available barcode printer.

Cut this into a predetermined size, paste it on an iron plate,
For 5 minutes. As a result, there was no change in the shape, and the image could be read by the scanner. Also, about 265
No change in shape even when immersed in a solder bath for 20 seconds
I could read it with a scanner.

Example 2 A film was prepared in the same manner as in Example 1 except that PPTA having an η inh of 3.8 was dissolved in 99.8% sulfuric acid so as to be 13%, and the linear velocity discharged from the die was 3.5 m / min. Obtained.

The resulting film is transparent, has a thickness of 45 μm, and has a tensile strength of 35.
kg / mm ^2, tensile elastic modulus 1530kg / mm ^2, density of 1.40g / cm ^3, 250 ℃
Was 0.15%.

A bar code was printed on the obtained film in the same manner as in Example 1.

Cut this into a predetermined size, paste it on an iron plate, 400 ℃
In the oven for 2 minutes. As a result, there was no change in the shape, and the image could be read by the scanner.

Comparative Example 1 A barcode was printed on a 20-μm polyester film in the same manner as in Example 1.

Cut two pieces of this into a predetermined size and paste them on an iron plate.
One was placed in a 300 ° C. oven for 5 minutes and the other was placed in a 400 ° C. oven for 2 minutes. As a result, the former had severe shrinkage of the film, and the latter melted the film, and neither could be read by a scanner.

〔The invention's effect〕

The heat-resistant barcode of the present invention is particularly effective for use in a high temperature range of 200 to 450 ° C., and in various industries such as the electronic and electrical industries, a process management requiring heat resistance, production management, Useful for quality control, etc.

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁶ , DB name) G06K 19/00-19/18 G09F 3/00

Claims (1)

(57) [Claims] (1) having a strength of 10 kg / mm ² or more in any direction;
And a heat-shrinkage ratio at 250 ° C. of not more than 0.5% is substantially 0.5% or less, and a film of a para-oriented aromatic polyamide is coated with a silicone-based pressure-sensitive adhesive made of polysiloxane. Heat resistant barcode label used in high temperature range.