JPS623984A - Label for thermal recording - Google Patents

Abstract

PURPOSE:To enhance image preservability and heat response characteristics and enable a sufficient developed color image to be obtained even with low energy, by providing a thermal color forming layer comprising as color forming components a reactant of a specified imino compound and a co-reactant of an aromatic isocyanate compound capable of reacting with the reactant when being heated, on the surface of a base. CONSTITUTION:The thermal color forming layer comprising a colorless or light-colored reactant and a co-reactant capable of reacting with the reactant when being heated as color forming components is provided on the face side of the base, and an adhesive layer is provided on the back side. The reactant is an imino compound of formula (1), wherein (x) is halogen, (n) is an integer of 0-4, and A is C=O or C=NH. The co-reactant is an aromatic isocyanate compound of formula (2), namely. 2,5-dimethoxy-4,4',4''-triisocyanate-triphenyl amine. Accordingly, a developed color image with a purplish hue can be obtained. In addition, a releasable paper is provided on the surface of the adhe sive layer capable of adhering to a separate solid surface.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a two-component color-forming heat-sensitive recording label that has excellent storage stability of color-forming recorded images.

(Prior Art) Thermal recording labels are POS (point of sale, barcode labels for pipe and paper systems, barcode labels 51 price display) 9 servers.

Delivery/shipping label 4. It is difficult to attach it after printing. 4. P!
It is used for A purpose. In particular, the popularity of POs systems is remarkable in large-scale mass retailers such as supermarkets and department stores, as well as chain-operated specialty stores, restaurants, and the like. The purpose is to aggregate and analyze product sales information in order to clearly understand consumer needs and formulate rational management strategies. Currently, methods of optically reading barcodes and OCR characters using scanners are rapidly growing.

The manual method of these recording methods uses a two-component heat-sensitive recording label, which has a coloring layer containing a reactant and a co-reactant on a support, and generates one reaction by applying heat to the label. In this method, the body and co-reactant are brought into contact with each other and recorded as a colored image. Among these, many use a leuco dye, which is a dye precursor, and a color developer, which is an acidic substance, as reactants and co-reactants. The heat-sensitive recording label Fi using these conventionally known leuco dyes has many excellent properties such as high whiteness, good recording suitability such as 5 color development layers with an appearance and feel similar to plain paper. Since then, its uses have expanded. On the other hand, heat-sensitive recording labels using these leuco dyes, for example, crystal violet lactone and 4.4'-
Similar to thermal paper that uses isoglopylidene diphenol (bisphenol A) as a coloring agent (see U.S. Patent No. 5,559,375, etc.), the chemical resistance of the recorded area obtained by coloring is poor, so it is difficult to use plastic sheets or erasers. Records may easily disappear when they come into contact with plasticizers contained in foods or chemicals contained in foods or cosmetics, and because the light resistance of the recorded portion is poor, records may fade with relatively short exposure to sunlight. It has the disadvantage that the storage stability of the record is poor, such as the recording being lost or even disappearing.

Therefore, in order to protect the colored image, a protective layer is formed in advance on the colored layer to prevent penetration of plasticizers and the like, thereby improving the storage stability of the colored image formed by the colored layer. However, if a discontinuous portion such as a pinhole occurs in the protective layer, the plasticizer or the like will permeate through that portion due to contact with the plasticizer, causing deterioration and discoloration of the recorded area. Furthermore, if the protective layer is made thicker in order to completely prevent the penetration of plasticizers, etc., the transfer of heat to the coloring layer will be reduced, resulting in a decrease in sensitivity and the like.

(Problems to be Solved by the Invention) As mentioned above, in conventional heat-sensitive recording labels, the storage stability of colored recorded images is poor9, and it is necessary to form a protective layer on the colored layer in advance. Fi, sufficient storage stability has not been obtained. Therefore, the colored image produced by the coloring layer has sufficient image storage stability without the need for a protective layer at all or even with an extremely thin protective layer, and furthermore, it has excellent thermal responsiveness, and sufficient colored images can be obtained even with low energy. It is hoped that

(Means for Solving the Problems) An object of the present invention is to provide a heat-sensitive recording label with excellent storage stability of colored images.

A thermosensitive recording in which a thermosensitive coloring layer containing a colorless or light-colored reactant and a co-reactant that reacts with the print reactant as coloring components is formed on the surface of the support, and an adhesive layer is provided on the back surface of the support. In the label, the reactant is an imino compound represented by the following general formula, NH (wherein, X is a halogen atom, and n is an integer from 0 to 4.

If the number is 0 or 0, it means C-Nu. ) The heat-sensitive recording label is characterized in that the co-reactant is an aromatic isocyanate compound.

An imino compound having a group has the general formula φC=NH(φ
Aromatic compound residues that can form a conjugated system with adjacent C--N are compounds represented by the following formula, and are colorless compounds that are solid at room temperature and are light-colored. It is possible to use two or more types of imino compounds in combination depending on the purpose, as shown in specific examples below.

3-iminoisoindolin-1-one, 5-imino-4
, 5,4,7-titrachloroisoindolin-1-one, 5-imino-4,5,6,7-tetrabromoisoindolin-1-one, 5-imino-4゜5.6.7- Citrafluoroinoindolin-1-one, 3-imino-
5,6-dichloroisoin 1 dolin-1-one, 1.3
-diiminoisoindoline, 1,5-diimino-4,5
, 4,7-titrachloroisoindoline, 1,3-diimino-4,5,6,7-titrafluoroisoindoline%
Examples include 1,5-diimino-5°6-dichloroisoindoline.

The aromatic inocyanate used in the present invention is a colorless or light-colored aromatic inocyanate or a heterocyclic inocyanate that is solid at room temperature. For example, one or more of the following are used.

2.6-cyclophenylisocyanate)% p-chlorophenylisocyanate% 1,5-phenylene diisocyaner)% '*4-phenylene diisocyaner) b 1s3-dimethylbenzene-4,6-diisocyanate 1,4-dimethylbenzene-2,5-diisocyanate, 1-methoxybenzene-2,4-diisocyanate, 1-methoxybenzene-2゜5-diisocyanate), 1-ethoxybenzene-2゜4-diisocyanate, 2,5-dimethoxybenzene-1,4-diisocyanate, 2,5-jethoxybenzene-1,4-diisocyanate, 2,5-dibutoxybenzene-1,4-
Diisocyanate, azobenzene-4,4'-diisocyanate, diphenyl ether-4,4'-diisocyanate, naphthalene-1,4-diisocyanate, naphthalene-1,5-diisocyanate, naphthalene-2,
6-diisocyanate, naphthalene-2,7-diisocyanate, 5,3'-dimethyl-biphenyl-4,4'
-diisocyanate, 5,3'-dimethoxybiphenyl-4,4'-diisocyanate, diphenylmethane-4
, 4'-diisocyanate, diphenyldimethylmethane-4,4'-diisocyanate, benzophenone-5゜5'-diisocyanate, fluorene-2,7-') incyanate, anthraquinone-2,6-diisocyanato r
t-),? -Ethylcarbasol-5,4-diisocyanate, pyrene 6,8-diisocyanate, naphthalene-1,5,7-dolyisocyanate, biphenyl-2,
Examples include 4,4'-) diisocyanate, p-dimethylaminophenyl isocyanate, tris(4-phenylisocyanate) thiophosphate, and the like. These incyanates may be used in the form of so-called blocked isocyanates, which are addition compounds with phenols, lactams, oximes, etc., as necessary, and dimers of diisocyanates, such as 1-methyl Benzene-2,4-
It may be used in the form of diisocyanate dimer and pentamer isocyanurate, and it can also be used as polyisocyanate adducted with various polyols.

A colored image is obtained by contact spreading of these imino compounds and isocyanate compounds by heating. The hue of this colored image is determined by the combination of these two components;
It can be varied over a wide range of colors such as yellow. In particular, in recent years, black colors have been preferred as colored images, but in general, the hue of colored images is often reddish black, and it has been difficult to obtain colored images with purplish black.

As the isocyanate compound according to the present invention, in particular, 2,5-dimethoxy-4,4',4"-) represented by the following formula:
It can be seen that by using the socyanate, totriphenylamine, a color image with four purplish hues can be obtained.This isocyanate can be used as necessary, such as phenols, lactams, oximes, etc. The so-called blocked isocyanate 0 form 1, which is an addition compound with , can also be used. ・In the 2 bell for heat-sensitive writing paper of this invention, in addition to the color-forming component, the heat-sensitive color-forming layer contains The main ingredients added will be described in detail.

As a binder #i, starch, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, polyvinyl alcohol,
Modified polyvinyl alcohol.

Styrene-maleic anhydride copolymer, ethylene-1
〇 − Water-soluble binder such as maleic anhydride copolymer.

Examples include latex-based water-soluble binders such as styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, and methyl acrylate-butadiene copolymer.

Examples of pigments include kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, titanium oxide, zinc oxide, silicon oxide, aluminum hydroxide, urea-formalin resin, and the like.

(In addition to -, higher fatty acid metal salts such as zinc stearate and calcium stearate, paraffin, oxidized paraffin, polyethylene, polyethylene oxide, stearic acid amide,
Examples include waxes such as castor wax, dispersants such as sodium dioctyl sulfosuccinate, ultraviolet absorbers such as benzophenone and benzotriazole, surfactants, and fluorescent dyes.

Since the heat-sensitive recording label of the present invention has excellent image storage stability of the colored image, it is sufficient to form only the coloring layer on the surface of the support. A protective layer may also be provided.

As the main component of the protective layer, various water-soluble resins, latex, and photocurable resins are used. i, if necessary,
Pigments, waterproofing agents, water repellents, antifoaming agents, ultraviolet absorbers, etc. can be added. Also.

The back side of the support is provided with an adhesive layer that can adhere to another solid surface. 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 various woven fabrics, plastic films, synthetic papers, metal foils, etc., or composite sheets made of combinations of these may optionally be used. be able to.

(Example) Next, the present invention will be explained in more detail using examples.

Example 1 10f of 1,3-diimino-4,5,6,7-titrachloroisoindoline in 1 part in 4 parts in tivolivinyl alcohol aqueous solution
01 and was dispersed in a ball mill for 24 hours. On the other hand, 2
,5-dimethoxy-4,4',4"-triisocyanato-triphenylamine 109 was dispersed in a ball mill for 24 hours with 40 f of a 1-predominant aqueous polyvinyl alcohol solution. After mixing these two dispersions, calcium carbonate Added 60f of a 50% dispersion of zinc stearate, and further added 40f of a 25% dispersion of zinc stearate, 140f of a 10-polyvinyl alcohol aqueous solution, and 60f of water, and stirred thoroughly to prepare a coating solution.This coating solution weighed 55f/vt. The coated paper was coated and dried at a solid coating weight of 6 f/rrt.A release paper having an adhesive layer was provided on the back side of the obtained coated paper to obtain a heat-sensitive recording label.

Example 2 1,3-diimino-4,5,6,7- used in Example 1
3-imino-4 as a substitute for titrachloroisoindoline,
A heat-sensitive recording label was obtained in the same manner as in Example 1 except that 5,6,7-titrachloroisoindolin-1-one was used.

Example 5 2,5-dimethoxy-4,4',4'' used in Example 2
-Triisocyanate-A heat-sensitive recording label was obtained in the same manner as in Example 2, except that tridine diisocyanate was used instead of triphenylamine.

Comparative Example 1 1,5-diimino-4,5,4,7- used in Example 1
2-anilino-5 instead of titrachloroisoindoline
-Methyl-6-dinithylaminofluorane, also 2
．． A heat-sensitive recording label was obtained in the same manner as in Example 1, except that CK4,4'-isopropylidenediphenol was used instead of 5-dimethoxy-4,4',4"-triisocyanate-triphenylamine. .

The heat-sensitive recording labels obtained in Test Examples 1 to 5 and Comparative Example 1 were applied with a heat-sensitive label printer for application passes of 2 and 81, respectively.
Printing was performed under the conditions of rLwt and applied voltage of 22.7 V.

The hue of the obtained colored image was visually determined, and the results are shown in the table.

In addition, one drop of dioctyl phthalate, which is used as a plasticizer for colored images, was added, and changes in the image after one minute were examined, and the results are also shown in the table.

(Effects of the Invention) As shown in the table, the storage stability of a single color image is excellent and five hues can be selected. Furthermore, by selecting a 4t) constant incyanate compound, a purplish black color can be obtained.

Claims (2)

[Claims] (1) A thermosensitive coloring layer containing a colorless or light-colored reactant and a co-reactant that reacts with the reactant during heating as a coloring component is formed on the surface of the support, and an adhesive layer is provided on the backside of the support. In the heat-sensitive recording label, the reactant is an imino compound represented by the general formula below, and there are mathematical formulas, chemical formulas, tables, etc. (wherein, X is a halogen atom, n is an integer from 0 to 4, and A represents C=O or C=NH.) A heat-sensitive recording label, wherein the co-reactant is an aromatic isocyanate compound. (2) The aromatic isocyanate compound has the following formula ▲ mathematical formula,
There are chemical formulas, tables, etc. ▼ The heat-sensitive recording label according to claim 1, which is a compound represented by ▼.