JPS61175077A - Label for thermal recording - Google Patents

Abstract

PURPOSE:To obtain color pictures having absorbances in near infrared rays which are readable by semiconductor lasers by using a specific fluorene compound as leuco dye. CONSTITUTION:A thermal color-forming layer containing a colorless or light- color leuco dye and a developer as color-forming components and a protective layer are formed in order on the surface of a supporter, and an adhesive layer is provided on the back side of the supporter. The leuco dye used is a fluorene compound of the formula, (where R1, R2, R3, R4, R5, and R6 are each a lower alkyl group). The use of the fluorene compound enables one to obtain color pictures of blue to green color. To regulate the color tone of the color pictures, a leuco dye which gives color pictures of red color or black color may be used jointly within a range not to damage the aim of thermal printing.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a two-component coloring type heat-sensitive recording label.

B. Prior art Thermal recording labels are used in applications that require pasting after printing, such as barcode labels for PO3 (point of sale) systems, price display labels, and delivery/shipping labels. In particular, POS systems are becoming more popular in large-scale mass retailers such as supermarkets and department stores, as well as chain specialty stores and restaurants. The purpose is to aggregate and analyze product sales information in order to clearly understand consumer needs and formulate a comprehensive management strategy.
As one of these methods, the method of optically reading barcodes and OCR characters displayed on products sold in stores using a scanner is currently rapidly gaining popularity.

Ear 11 Therefore, various printing methods are currently being tried, but among them, the thermal recording method is said to be the most superior.

This is because the printing method uses chemical or physical changes in substances due to heating to record images, and does not require development and fixing, nor does it require replenishment of printing ink.

That is, this is because the machine has many features, such as being able to downsize and simplify the machine and speed up recording, and there is no need to worry about ink staining hands or products or ink fading.

In addition, to read colored images such as bar codes, He/Ne laser light with a red light wavelength of 633 nm has traditionally been used, but semiconductor lasers have recently come into use. This is widely used because it can be directly modulated by current, can be miniaturized, is easy to use, is low cost, and has the advantage of being less likely to malfunction due to dirt because the oscillation wavelength is in the near-infrared range of 700 to 1500 nm. I've been doing it.

Therefore, it is desired to obtain colored images that can be read with a semiconductor laser even on heat-sensitive recording labels. However, in the conventionally used two-component heat-sensitive recording material consisting of a leuco dye and a color developer, the absorption wavelength of the colored image is 550 to 62 on the long wavelength side even in black colored thread.
Since it was 0 nm, it was possible to read it with a He.Ne laser beam, but it was not possible to remove it with a semiconductor laser having a near-infrared Qv length.

C8 OBJECTS OF THE INVENTION An object of the present invention is to provide a heat-sensitive recording label capable of producing a colored image absorbing in the near-infrared region that can be read by a semiconductor laser.

Constituent structure of the C0 invention A heat-sensitive recording material in which a heat-sensitive color forming layer containing a colorless or light-colored leuco dye and a color developer as color-forming components and a protective layer are sequentially formed on the surface of a support, and an adhesive layer is provided on the back surface of the support. In the label, by using a fluorore/compound represented by the following general formula as the leuco dye, the intended heat-sensitive recording label can be provided.

In the general formula, R11R21R31R4# R51 and R6
each represents a lower alkyl group.

The fluorene compound represented by the above general formula is a colorless to light-colored crystal that does not have absorption in the near-infrared region, but it develops a color from blue to green by reaction with a color developer, and its color image source is in the near-infrared region. has absorption.

Specific examples of the fluorene compound according to the present invention include 3,6-bis(dimethylamino)fluorene-9-
Spil: I-3'-(6'-dimethylaminophthalide)
, 3-diethylamine-6-dimethylaminofluorene-9-spiro-3'-(6'-dimethylaminophthalide), 3,6-bis(diethylamino)fluorene-9
-spiro-3'-(6'-dimethylaminophthalide)
, 3-dibutylamino-6-dimethylaminofluorene-9-spiro-3'-(6'-dimethylaminophthalide), 3-dibutylamino-6-dietheraminofluorene-9-spiro-3'-( 6'-dimethylaminophthalide), 3゜6-bis(dimethylamino)fluorene-
9-spiro-3'-(6'-diethylaminophthalide), 3-diethylamino-6-dimethylaminofluorene-9-spiro-3'-(6'-diethylaminophthalide), 3-dibutylamino-6-dimethyl Aminofluorene-9-spiro-3'-(6'-diethylamino7
3.6-bis(dimethylamino)fluorene-9-spiro-3'-(6'-dibutyl aminophthalide), 3
-dibutylamino-6-diethylaminofluorene-9
-spiro-3'-(6'-diethylaminophthalide),
Examples include 3-diethylamino-6-dimethylaminofluorene-9-spiro-3'-(6'-dibutylamino 7-thallide).

By using the fluorene compound according to the present invention, colored images ranging from blue to green can be obtained. In order to adjust the tone of this colored image, a leuco dye capable of producing a red or black colored image can be used in combination within a range that does not impede the object of the present invention. Examples of such leuco dyes include:
2-anilino-3-methyl-6-N-methyl-N-cyclohexylaminofluorane, 2-anilino-3-methyl-6-dinithylaminofluorane, 2-anilino-3
-Methyl-6-N-ethyl-N-yriamylaminofluorane, 2-(2'-chloroanilino)-6-dinithylaminofluorane, 2-(2'-chloroanilino)-6
-sibutylaminofluorane, 2-anilino-3-methyl-6-N-ethyl-N-P-tolylaminofluorane, 2-anilino-3-methyl-6-pyrrolidinofluorane, 2-P-phenetidino 3-Methyl-6-dinithylaminofluorane, 2-m-trifluoromethylanilino-6-dinithylaminofluorane, 2-chloro-3-
Methyl-6-dinithylaminofluorane, 2-chloro-
6-dinithylaminofluorane, 3゜3-bis(1-octyl-2-methylindol-3-yl)phthalide,
etc.

An electron-accepting compound is used as the color developer according to the present invention. For example, phenol, P tert-butylphenol, P-phenylphenol, α-naphthol, P
-Hydroxyacetophenol, 2,Z-dihydroxydiphenol, 4,4'-isopropylidene bis(2-
tert-butylphenol), 4.4'-isopropylidene diphenol, 4.4'-cyclohexylidene diphenol, novolac type phenol resin, benzoic acid,
P-tert-butylbenzoic acid, P-oxybenzoic acid,
P-oxybenzoic acid benzyl ester, P-oxybenzoic acid methyl ester, 3-benzyl-4-hydroxybenzoic acid, β-naphthoic acid, salicylic acid, 3-tert
-butylsalicylic acid, 3-methyl-5-tert-butylsalicylic acid, stearic acid, oxalic acid, maleic acid and the like.

In the heat-sensitive recording label of the present invention, the main components that may be added in addition to the color-forming components in the heat-sensitive color-forming layer as necessary will be specifically described.

Examples of binders include starches and water-soluble binders such as droxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol, styrene-maleic anhydride copolymer, and ethylene-maleic anhydride copolymer. , styrene/butadiene copolymer, acrylonitrile-butadiene copolymer, and methyl acrylate-butadiene/copolymer.

Examples of pigments include diatomaceous earth, talc, kaolin, calcined kaolin, calcium carbonate, magsium carbonate, sodium oxide, zinc oxide, silicon oxide, aluminum hydroxide, urea-formalin resin, and the like.

In addition, higher fatty acid metal salts such as zinc stearate and calcium stearate, waxes such as paraffin, oxidized paraffin, polyethylene, polyethylene oxide, stearic acid amide, and castor wax are used to prevent head wear and stickiness. , dispersants such as dioctylsulfocono-sodium phosphate, ultraviolet absorbers such as benzophenone and benzotriazole threads, surfactants, and fluorescent dyes.

The heat-sensitive recording label of the present invention has a heat-sensitive coloring layer provided on the surface of a support, and a protective layer further provided on top of the heat-sensitive coloring layer. The protective layer is provided to protect the uncolored areas and colored image areas of the thermosensitive coloring layer from the external environment, and its main components are:
Various water-soluble resins, latex, and photocurable resins are used. Further, pigments, water-resistant agents, water repellents, antifoaming agents, ultraviolet absorbers, etc. can be added as necessary.

Further, an adhesive layer capable of adhering to another solid surface is provided on the back surface of the support. A release paper is provided on the surface of this adhesive layer.

Paper is mainly used as the support for the heat-sensitive recording label of the present invention, but nonwoven fabrics, plastic films, synthetic papers, metal foils, etc., or composite sheets of combinations of these may also be used as desired.

E. Example Next, the present invention will be explained in more detail with reference to Examples.

Example 1 3.6-bis(dimethylamino)fluorene-9-spiro-3'-(6'-dimethylaminophthalide) 20f
With Ik1% polyvinyl alcohol aqueous solution 80y,
Dispersed using a ball mill. On the other hand, bisphenol A50
It was dispersed in a ball mill together with 200 tons of 1% Fe aqueous polyvinyl alcohol solution. After mixing these dispersions, 250 g of 40 g of carbonic acid dispersion was added, and 9 g of 25% zinc stearate dispersion, 20 of 25% stearamide dispersion, and 625 g of 8% polyvinyl alcohol water bath solution were added. The mixture was thoroughly stirred to form a coating solution.

This coating liquid was applied as a solid layer onto a base paper having a basis weight of 55 mm, and dried to form a heat-sensitive coloring layer. Next, an overcoat solution in which calcium carbonate 50F and 10% polyvinyl alcohol aqueous solution 5009% hardener 5v were uniformly mixed was applied onto the heat-sensitive coloring layer to a solid coating amount of 5 f/- and dried. All the protective layers were used. A release paper having a sticky layer was provided on the back side of the obtained coated paper to obtain a heat-sensitive recording label.

Comparative Example 1゜2-anilino-3-methyl-6-dini was added to the 3.6-bis(dimethylamino)fluorene-9-spiro-3'-(6'-dimethylaminophthalide) of Example 1. A heat-sensitive recording label was obtained in the same manner as in Example 1 except that thylaminofluoran was used.

Evaluation example 1. The heat-sensitive recording label obtained in Comparative Example 1 was evaluated as follows, and the results are shown in Table 1.

(1) Color density: Printing was performed under the conditions of 16.00 V and 3.0 milliseconds, and the optical a degree of the colored image was measured using a Macbeth densitometer RD918 through a 624 nm filter.

(2) Near-infrared light reading: GaAs semiconductor laser (78
0nm) to check whether barcodes could be read.

As is clear from F. Effect Clothing 1, the color image of the heat-sensitive recording label of the present invention can be etched with a laser conductor having near-infrared light.

Claims (1)

[Scope of Claims] A heat-sensitive device in which a heat-sensitive coloring layer containing a colorless or light-colored leuco dye and a color developer as color-forming components and a protective layer are sequentially formed on the surface of a support, and an adhesive layer is provided on the back surface of the support. 1. A heat-sensitive recording label, wherein the leuco dye is a fluorene compound represented by the following general formula. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R_1, R_2, R_3, R_4, R_5 and R_6 each represent a lower alkyl group.)