GB2192288A

GB2192288A - Thermosensitive recording materials

Info

Publication number: GB2192288A
Application number: GB08713896A
Authority: GB
Inventors: Philip G Walter; Yukihiro Yuyama; Kenji Uematsu; Hiroaki Okuda; Hideo Aihara
Original assignee: Ricoh Co Ltd
Current assignee: Ricoh Co Ltd
Priority date: 1986-06-16
Filing date: 1987-06-15
Publication date: 1988-01-06
Anticipated expiration: 2007-06-15
Also published as: NL193991C; CA1283780C; SE8702462L; NL8701403A; GB8713896D0; SE8702462D0; GB2192288B; DE3720171A1; SE500916C2; NL193991B; DE3720171C2

Description

GB2192288A 1

SPECIFICATION

Thermosensitive recording materials The present invention relates to thermosensitive recording materials in which the recording layer 5 contains a fluorescent dye composition.

Conventional thermosensitive recording materials comprise a support, for example a sheet of ordinary or synthetic paper, having a thermosensitive recording layer formed on the support.

Coloured images are formed in the recording layer by the imagewise application of heat. Thermal printers provided with a thermal print head, thermal pens and infrared application devices are 10 generally used to print on thermosensitive recording materials.

Because of their ability to form coloured images by the simple application of heat, such thermosensitive recording materials are widely used, not only for copying books and documents, but also for recording output information from computers, facsimile apparatus, telex and other information transmission and measuring instrucments. Furthermore, such thermosensitive record- 15 ing materials may be employed as railway tickets and as adhesive labels for the POS (point of sale) labelling system in supermarkets and department stores, There is known a thermosensitive recording adhesive label comprising a support having a thermosensitive recording layer formed on its front side and an adhesive layer formed on its reverse side, the label also having a disposable backing sheet attached to the adhesive layer and 20 which can be peeled from the adhesive layer when the label is to be used.

Such a thermosensitive adhesive label can be attached to a variety of commerical products.

Using such a label a product can be identified by thermally printing, for instance, the product name, price and/or bar code on the label, and aplying the thermally printed label to the product with the backing sheet removed. The thermally printed bar codes can be read by automatic 25 reading apparatus and the information processed by computer, so that, for instance, the sale, stock and records of the product can be controlled. Furthermore, the label can be used for other purposes, for instance as a merchandising marker by which customers can readily distinguish particular products from other products, for example for readily identifying specially discounted products. 30 To improve product recognition, it has been proposed to print graphics, numbers, letters and bar codes with coloured ink onto a white thermosensitive recording label. It has also been proposed to print such figures or bar codes on a label coated with a fluroescent ink containing a fluorescent dye or pigment. The former method, however, has the shortcomings that printing with a coloured ink is time-consuming and costly and the printed portions result in the formation 35 of dust which adheres to a thermal printing head in the course of thermal printing so that subsequent thermally printed portions can become smeared with the dust. When the bar code is pre-printed on the label to partially overcome this problem, there is the disadvantage that a sufficient quantity of pre-printed bar-code labels must be stocked for each product.

When thermosensitive recording adhesive labels are used, particularly in food packaging, they 40 may come into contact with oils (for instance oils contained in foods) and plasticizers (for instance plasticizers contained in plastics wrapping films). When the developed coloured images come into contact with such oils and plasticizers they are frequenctly discoloured or become blurred. It is therefore desirable that thermally printed images be prevented from being disco- loured or becoming blurred even if they are brought into contact with such materials. 45 It is an object of the present invention to provide an improved thermosensitive recording material which is readily recognized.

According to the invention there is provided a thermosensitive recording material comprising a support having a thermosensitive recording layer formed on one side thereof, the thermosensi tive recording layer comprising (i) a thermosensitive colouring system capable of producing a 50 colour upon the application of heat thereto, and (ii) a coloured fluorescent dye composition.

In a preferred embodiment the invention provides a recording material having a high recogni tion function which is useful in labelling products and which is provided with an adhesive layer on the side of the support opposite the thermosensitive recording layer and, optionally, a disposable backing sheet on the adhesive layer. 55 The recording material of the invention may also include a barrier layer which may be applied over the thermosensitive recording layer or to the reverse side of the support to protect the layer from materials which could discolour the image developed in the layer. A barrier layer disposed on the front side of the material also serves to improve thermal head life. A reverse barrier layer may be interposed between the support and any optional adhesive layer to further 60 protect the thermosensitive recording layer from adverse materials which may discolour the images developed therein. This is desirable when the thermosensitive label is to be applied to a material, such as a plastic foil, which contains agents such as plasticizers which may cause discolouration.

In the following description reference will be made to the accompanying drawings in which: 65

2 GB2192288A 2 Figures 1-1 and 1-2 are schematic cross-sections through examples of a first embodiment of thermosensitive recording material according to the invention; Figures 2A-1 to 2A-3 are schematic cross-sections through examples of a second embodi- ment of thermosensitive recording material according to the invention; Figures 2B-1 to 2B-3 are schematic cross-sections through examples of another variation of 5 the second embodiment of thermosensitive recording material; Figures 2C-1 to 2C-3 are schematic cross-sections through examples of a further variation of the second embodiment of thermosensitive recording material; Figures 3-1 to 3-3 are schematic cross-sections through examples of a third embodiment of thermosensitive recording material according to the invention; and 10 Figures 4-1 to 4-6 are schematic cross-sections through examples of a fourth embodiment of thermosensitive recording material according to the invention.

A thermosensitive recording material according to the invention comprises (a) a support and (b) a thermosensitive recording layer formed on one side (the display side or front) of the support; which thermosensitive recording layer comprises (i) a thermosensitive colouring system 15 capable of forming a colour upon the imagewise application of heat thereto, and (ii) a coloured fluorescent dye composition. In accordance with the preferred and most typical embodiment of the invention, the recording material additionally includes (c) an adhesive layer formed on the reverse side of the support.

The support may be any support material such as is employed in conventional thermosensitive 20 recording materials and typically may be a cellulosic or synthetic paper.

The thermosensitive recording layer may, for example, have any of the following structure types.

Type 1 25 A single thermosensitive recording layer comprising a thermosensitive colouring system and a coloured fluorescent dye composition, which layer is formed on the support.

When a recording layer of this type is used, a barrier layer may be formed on the thermosen sitive colouring layer and/or on the reverse side of the support.

30 Type 2 A thermosensitive recording layer comprising (i) a thermosensitive colouring layer comprising a thermosensitive colouring system and (ii) a coloured layer comprising a coloured fluorescent dye composition, which are successively overlaid on the support.

A barrier layer may be formed at least on the coloured layer or on the reverse side of the 35 support, or between the thermosensitive colouring layer and the coloured layer.

Type 3 A thermosensitive recording layer comprising (i) a coloured layer comprising a coloured fluores- cent dye composition and (ii) a thermosensitive colouring layer comprising a thermosensitive 40 colouring system, which are successively overlaid on the support.

A barrier layer may be form ' ed at least on the thermosensitive colouring layer or on the reverse side of the support, or between the thermosensitive colouring layer and the coloured layer.

45 Type 4 A thermosensitive recording layer comprising (i) a thermosensitive colouring layer comprising a thermosensitive colouring system and a coloured fluorescent dye composition and (ii) a coloured layer comprising a fluorescent dye composition, which layers are successively overlaid on the support. 50 A barrier layer can be formed at least on the coloured layer or on the reverse side of the support, or between the coloured layer and the thermosensitive colouring layer.

Type 5 A thermosensitive recording layer comprising (i) a coloured layer comprising a coloured fluores- 55 cent dye composition and (ii) a thermosensitive colouring system and a coloured fluorscent dye composition, which are layers successively overlaid on the support.

A barrier layer may be formed at least on the thermosensitive colouring layer or on the reverse side of the support, or between the thermosensitive colouring layer and the coloured layer. 60 Any barrier layer present serves to protect the thermosensitive recording layer from adverse materials, such as oils and plasticizers, which may discolour images developed in the recording layer. The barrier layer preferably comprises a water-soluble polymeric material such as polyvinyl alcohol, ca rboxymethylcellu lose, methylcellulose, ethylcellulose, hydroxpropylcellulose, hydroxye thylcellulose, polyacrylamide, starch, resins dispersed in water, for instance polystyerne emul- 65 3 GB2192288A 3 sions can also be employed in the barrier layer.

To make the barrier layer waterproof, the following waterproofing agents can be employed, namely: formaldehyde, glyoxal, chromium alum, melamine, melamine- formaldehyde resins, poly amide resins and polyamide-epichlorohydrin resins.

Conventional inorganic and organic fillers may be present in the thermosensitive colouring 5 layer, the coloured layer, and the barrier layer, particularly in a front- side barrier layer formed on the thermosensitive recording layer,'to improve the thermal head matching properties of the recording material.

The thermosensitive colouring layer and coloured layer may contain conventional binders such as gelatin, starch, hydroxymethylcellu lose, hydroxyethylcellulose, polyacrylic acid, carboxymethyl- 10 celulose, ca rboxyethylcellu lose, methylcellulose, ethylcellulose, methoxycellulose, polycellulose, polyvinyl alcohol, polyacrylamide, casein and polyvinyl pyrrolidone. In addition, waterproofing agents, as used in the barrier layer, can also preset the thermosensitive colouring layer and in the coloured layer.

Thermosensitive colouring systems which may be used in the thermosensitive recording layer, 15 include:

(1) a thermosensitive colouring system comprising a combination of (a) a long-chain fatty acid iron salt, such as iron stearate or iron myristate, and (b) a phenolic compound such as tannic acid, gallic acid or ammonium salicylate; (2) a thermosensitive colouring system comprising a combination of (a) a heavy metal sulphate, 20 such as silver, lead, mercury or thorium sulphate, and (b) a sulphur compound such as sodium tetrathionate, sodium thiosulphate or thiourea; (3) a thermosensitive colouring system comprising a combination of (a) an organic acid noble metal salt, such as silver behenate or silver stearate, and (b) an aromatic organic reducing agent such as protocatechuic acid, spiro-indane or hydroquinone; 25 (4) a thermosensitive colouring system comprising a combination of (a) an organic acid lead salt, such as lead caproate, pelargonate or behenate, and (b) a thiourea derivative such as theylenethiourea or N-dodecylthiourea; (5) a thermosensitive colouring system comprising a combination of a leuco dye and a colour developer capable of inducing colour formation in the leuco dye. 30 These thermosensitive colouring systems are well known and readily available.

In the colouring system comprising a combination of a leuco dye and a colour developer therefor, specific examples of suitable leuco dyes are:

3-[N-p-tolylamino)]-7-anilinofluoran, 35 3-[N-(p-toiyl)-N-methylaminol-7-anilinofluoran, 3-[N-(p-tolyi)-N-ethylamino]-7-anilinofluoran, 3-[N-(p-toiyl)-N-propylamino]-7-anilinofluoran, 3-dimethylamino-6-methyi-7-anilinofluoran, 3-diethylamino-6-methyi-7-anilinofluoran, 40 3-dipropylamino-6-mthyl-7-anilinofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3-pyrrolidino-6-methyi-7-anilinofluoran, 3-piperidinono-6-methyl-7-anilinofluoran, 3-piperazino-6-methyi-7-anilinofluoran, 45 3-N(N'-methylpiperazino)-6-methyl-7-anilinofluoran, 3-morpholino-6-methyl-7-anilinofluoran, 3-dibenzyiamino-6-methy]-7-anilinofluoran, 3-(N-methyi-n-cyclohexyi)-6-methy]-7-anilinofluoran, and 3-(N-cyclohexylamino)-6-methyl-7-anilinofluoran. 50 Specific examples of colour developers for the above leuco dyes are:

2,2'-methylenebis(4-ethyi-6t-butylphenol), 2,2'-methylenebis(4-methyi-6-t-butyI phenol), 4,4'-isopropylidenediphenol, 55 4,4'isopropylidenebis(2-chlorophenol), 4,4'-isopropyl idenebi s(2,6-dibromo phenol), 4,4'-isopropylidenebis(2,6-dichlorophenol), 4,4'-isopropylidenebis(2-methylphenol), 4,4'-isopropylidenebis(2,6-dimethylphenol), 60 4,4'-isopropylidenebis (2-t-butyl phenol), 4,4-sec-butylidenediphenol, 4,4-cyclohexyl idened i phenol, 4,4-cyclohexylidenbis(2-methylphenol), 2,2'-thiobis(4,6-dichlorophenol) and 65 4 GB2192288A 4 4,4'-(1 -methyl-n-hexylidene)diphenol.

In addition to the above there may be used a variety of electron accepting materials capable of inducing colour formatin in the above leuco dyes upon the application of heat thereto, for example phenolic and other organic acidic materials, inorganic acidic materials, and esters and salts thereof. 5 Specific examples of such colour developers are galic acid, salicyclic acid, 3-isopropyl salicyclic acid, 3-cyclohexyl salicyclic acid, 3,5-di- tert-butyl salicyclic acid, 3,5-di-a-methyibenzyi salicyclic acid, 4,4'- cyclohexylidenebisphenol, 4-tert-butylphenol, 4-phenylphenol, 4- hydroxydiphenoxide, anaphthol, fl-naphthol, 3,5-xylenol, thymoi, methyl-4- hydroxybenzoate, 4-hydroxyactophenone, no- volak-type phenolic resin, catechol, resorcinol, hydroquinone, pyrogallol, phloroglucine, phloroglu- 10 ocinorcarboxylic acid, 4-tert-octylcatechol, 2,2'-methylenebis(4- chlorophenol), 2,2'-dihydroxydi phenyl, ethyl p-hydroxybenzoate, propyl p-hyroxybenzoate, butyl p- hyroxybenzoate, benzy] p hyroxybenzoate, p-chlorobenzy] p-hydroxybenzoate, o-chlorobenzyl p- hydroxybenzoate, p-methyi benzyl p-hydroxybenzoate, n-octyl p-hydroxybenzoate, zinc salicylate, 1- hydroxy-2-naphthoic acid, 2-hydroxy-6-naphthoic acid, zinc 2-hydroxy-6-naphthoate, 4hydroxydiphenyisulphone, 4-hydroxy- 15 4'-chlorodiphenyisul phone, bis(4-hydroxy-phenyi)sulphide, 2-hydroxy-p- toluic acid, zinc 3,5-di-tert butylsalicylate, tin 3,5-di-tert-butyi-salicyate, tartaric acid, oxlic acid, maleic acid, citric acid, succinic acid, stearic acid, 4-hydroxyphthalic acid, boric acid, 4,4- methylenebis(oxyethylenethio)diphenol, 4-hydroxy-4 isopropoxyphenyl sulphone, and 1,5-di(4-hydroxy phenylthio)3-oxapentane.

The fluorescent dyes are preferably incorporated in the thermosensitive recording layer as a 20 resin grind, i.e. as a pulverized composition of a fluorescentdye and a resin, which is hereinafter referred to as the coloured fluorescent dye composition.

Specific examples of suitable fluorescent dyes are Thioflavine (C.I. 49005), Fluoresein (C.I.

35350), Brilliant sulphoffavine FF (C.I. 56205), Basic Yellow HG (C.I. 46040), Eosine (C.I.

45380), Rhodamine 6G (C.I. 45160) and Rhodamine B (C.I. 45170). 25 Specific examples of synthetic resins for use in the pulverized fluorescent dye composition are acrylic resins, polyester resins, polyamide resins. polyvinyl chloride resins, alkyd resins, aromatic sulphonamide resins, urea resins, melamine resins, benzoquanamine resins and copolymers thereof.

The pulverized fluorescent dye composition may be prepared by dyeing the resin with the 30 fluorescent dye in the course of preparation of the resin (for instance, in the course of emulsion polymerization) or by dissolving the flurorescent dye in the resin to form a solid solution, followed by pulverizing the coloured resin.

The average particle size of the pulverized fluorescent dye composition is preferably from 0.5 urn to 5 urn. 35 The thermosensitive colouring layer or the coloured layer may also contain conventional dyes and pigments.

As noted above, an adhesive layer may be formed on the reverse side of the support, and this adhesive layer, may be formed of any conventional adhesive agent such as, for example, an acrylic adhesive agent, a starch adhesive agent or a styrene-butadiene latex. Other pressure- 40 sensitive adhesives as conventionally used in adhesive labels may also be employed.

For convenience, a disposable backing sheet, such as silicone coated paper, m3y be attached to any adhesive layer; the backing sheet being peeled off the adhesive layer when the thermo- 25 sensitive recording material is to be used.

A first embodiment of recording material according to the invention will now be described 45 with reference to Fig. 1-1.

This recording material comprises a support having a thermbsensitive recording layer 2 formed thereon. The thermosensitive recording layer 2 is of Type 1 discussed above and constitutes colouring layer 2af containing a thermosensitive colouring system and a coloured fluorescent dye composition. 50 The coloured fluorescent dye composition suitably forms from 15 wt.% to 60 wt.%, preferably from 35 wt.% to 55 wt.%; of the weight of colouring layer af.

In order to protect recording layer 2, a front barrier layer 3 comprising a water-soluble polymeric material (as discussed above) may be formed on the recording layer 2, as shown in Fig. 1-2. 55 The barrier layer may also contain water-proofing agents and/or fillers as discussed above.

A barrier layer 4 may further be provided on the reverse side of support 1, as shown in Fig.

1-2.

Further, an adhesive layer 5 may be formed on the reverse barrier layer 4 or on the reverse side of support 1 (when no reverse barrier layer 4 is not present) and a disposable backing 60 sheet 6 may be attached to adhesive layer 5, as shown in Fig. 1-2.

Examples of recording materials in accordnace with the first embodiment are given in Examples 1-1 and 1-2 below.

A second embodiment of recording material according to the invention will now be described with reference to Figs. 2A-1 to 2A-3. This recording material comprises a support 1 having a 65 GB2192288A 5 thermosensitive recording layer 2 formed thereon. The recording layer 2 is of Type 2 discussed layer 2a, comprising a themosenitive colouring above and comprises a thermosensitive colouring system and a binder agent ' and a coloured layer 2c comprising a coloured fluorescent dye composition and a binder agent. Layer 2c is capable not only of serving as a coloured layer but is also capable of protecting colouring later 2a from adverse materials. An adhesive layer is 5 formed on the reverse side of support 1.

A disposable backing sheet 6 may be attached to adhesive layer 5 as shown in Fig. A-2.

Further, a release layer 7, made of, for example, a silicone resin, can be formed on coloured layer 2c as shown in Fig. 2A-3.

In this embodiment, the coloured fluorescent dye composition is not present in colouring layer 10 2a, but in coloured layer 2c.

The coloured fluorescent dye composition preferably forms from 10 to 95 wt.%, more preferably from 40 to 80 wt.%, of the weight of coloured layer 2c.

In order to improve the thermal head matching properties of colouring layer 2a, it is preferable that conventionally employed inorganic and organic fillers be present in coloured layer 2c and/or 15 colouring layer 2a. These second embodiments are illustrated in Example 2A below.. Figs. 213-1 to 213-3 illustrate another variation of the second embodiment of recording material according to the invention.

The recording material shown in Fig. 213-1 comprises a support 1 bearing a thermosensitive recording layer 2. The recording layer 2 is of Type 2 and comprises a thermosensitive colouring 20 layer 2a, comprising a thermosensitive colouring system and a binder agent, and a coloured layer 2c comprising a coloured fluorescent dye composition and a binder.

A barrier layer 2b is formed on colouring layer 2a. The barrier layer 2b may be the same as the front-side barrier layer 3 employed in the first embodiment of the invention. Fillers may be present in barrier layer 2b to improve its thermal head matching properties. 25 An adhesive layers is formed on the reverse side of support 1.

A disposable backing sheet 6 may be attached to adhesive layer 5 as shown in Fig. 213-3.

Coloured layer 2c is preferably present at a deposition rate of from 2 to 8 g/M2, more preferably 3 to 6 9/M2.

In order to improve the thermal head matching properties of the thermosensitive recording 30 layer 2, fillers may be present in colouring layer 2a and/or barrier layer 2b.

An example of this modififed recorded material is described in Example 213 below.

A further variation of the second embodiment of recording material according to the invention is shown in Figs. 2C-1 to 2C-3.

As shown in Figs. 2C-1 a recording material comprises a support 1 having a thermosensitive 35 recording layer 2 formed therein. Recording layer 2 is of Type 2 and comprises colouring layer 2a, comprising a thermosensitive colouring system and a binder agent, and coloured layer 2c comprising a coloured fluorescent dye composition and a binder. A barrier 2b is interposed between layers 2a and 2c and consists essentially of a resin for protecting colouring layer 2a.

An adhesive layer is formed on the reverse side of support 1. 40 A disposable backing sheet 6 may be attached to adhesive layer 5, as shown in Fig. 2C-2.

Further, a release layer 7, can be formed on coloured layer 2c, as shown in Fig. 2C-3.

The coloured fluorescent dye composition preferably forms from 10 to 95 wt.%, more prefera bly from 40 to 80 wt.%, of the weight of coloured layer 2c.

In order to improve the thermal headmatching properties of recording layer 2, fillers are 45 preferably present in colouring layer 2a and/or coloured layer 2c.

An example of this preferred embodiment of the invention is illustrated in Example 2C below.

A third embodiment of recording material according to the invention is shown in Figs. 3-1 to 3-3. The recording material comprises a support 1 having a thermosensitive recording layer 2 formed thereon. Recording layer 2 is of Type 3 discussed above and comprises a coloured layer 50 2c, consisting essentially of a coloured fluorescent dye composition and a binder, and a thermo sensitive colouring layer 2a, comprising thermosensitive colouring system and a binder.

An adhesive layer 5 is formed on the reverse side of support 1.

A disposable backing sheet 6 may be attached to adhesive layer 5, as shown in Fig. 3-2.

Further, a release layer 7 may be formed on coloured layer 2c, as shown in Fig. 3-3. 55 The coloured fluorescent dye composition preferably forms from 10 to 95 wt.%, more prefera bly from 40 to 80 wt.%, of the weight of coloured layer 2c.

In order to improve the thermal head matching properties of recording layer 2, fillers are preferably present in colouring layer 2a, and/or coloured layer 2c.

The third embodiment of the invention is illustrated in Example 3 below. 60 A fourth embodiment of recording material according to the invention is shown in Figs. 4-1 to 4-6. As shown in these drawings, a recording material comprises a support 1 having a thermosensitive recording layer 2 formed thereon. The thermosensitive recording layer 2 is of Type 4 discussed above and comprises a thermosensitive colouring system, a binder and a coloured fluorescent dye composition; and a coloured layer 2c comprising a coloured fluorescent 65 6 GB2192288A 6 dye composition and a binder.

A barrier layer 2b may be formed c coloured layer 2c, as shown in Fig. 42. Further, an adhesive layer 5 may be formed on the reverse side of support 1, as shown in Fig. 4-3.

As shown in Fig. 4-4, barrier layer 2b may be formed on coloured layer 2c and adhesive layer 5 may be attached to the reverse side of support 1. 5 Further, as shown in Fig. 4-5, an adhesive lyer 5 may be formed on the reverse side of support 1, and a disposable backing sheet 6 attached to adhesive layer 5.

Further, as shown in Fig. 4-6, in addition to adhesive layer 5 and disposable backing sheet 6, a barrier layer 2b may be formed on coloured layer 2c.

In these examples of this embodiment of the invention, an undercoat layer (not shown) 10 consisting essentially of a filler and a binder may be interposed between support 1 and colouring agent 2af to promote colouring of colouring layer 2af.

The coloured fluorescent dye composition is present not only in colouring layer 2af but also in coloured layer 2c, whereby a better recognition effect is attained as compared with the case where the coloured fluorescent dye composition is present only in colouring layer 2af. 15 The coloured fluorescent dye preferably forms from 15 to 60 wt.%. More preferably from 35 to 55 wt.%, of the weight of the colouring layer 2af.

The flurorescent dye composition preferably forms from 10 to 95 wt.%, more preferably from to 80 wt.%, of the weight of coloured layer 2c.

In order to improve the thermal head matching propoerties of recording layer 2, fillers are 20 preferably present in a coloured layer 2c and/or colouring layer 2a.

Examples of the fourth embodiment of the invention are illustrated in Examples 4-1 to 4-3 below.

In order that the invention may be well understood the following examples are given by way of illustration only. In the Examples all parts and percentages are by weight unless otherwise 25 stated.

Example 1- 1 (a) Preparation of Colouring Liquid and Colour Developer Liquid The following Liquids A and B were each prepared by grinding the respective components in a 30 ceramic ball mill for 24 hours:

Liquid A Parts 3-(N-ethyi-N-p-tolyi)amino-6 methyl-7-anilinofluoran 150 35 5% aqueous solution of polyvinyl 150 Water 200 Liquid B Parts Bisphenol A 120 40 Stearamide 120 5% aqueous solution of polyvinyl alcohol 120 Water 200 45 (b) Preparation of Fluorescent Dye Composition Liquid A mixture of the following components was dispersed in a ceramic ball mill until the average particle size of the fluorescent composition became 2 urn.

Liquid C Parts 50 Pulverized fluorescent dye composition (solid solution of Rhodamine B and melamine resin) 100 10% aqueous solution of polyvinyl alcohol 100 55 Dispersing agent (dialkyl sodium sulphosuccinate) 1 Water 100 (c) Preparation of Thermosensitive Recording Layer Coating Composition 60 Parts of Liquid A, 400 parts by Liquid B and 150 parts of Liquid C were mixed and dispersed. The resultant composition was coated onto a sheet of commercially available high quality paper (basis weight, 52 g/m2) at a coating rate of 10 g/M2 (when- dried) to form a thermosensitive recording layer containing a fluorescent dye composition on the paper.

7 GB2192288A 7 (d) Preparation of Front-side Barrier Layer Coating Composition A mixture of the following components was dispersed in a ceramic ball mill:

Liquid D Parts Carboxyl-group-modified 5 polyvinyl alcohol 50 Urea-formaldehyde resin filler 10 Polyamide epichlorohydrin resin 5 Water 500 10 The resultant composition (Liquid D) was coated onto the thermosensitive colouring layer at a rate of 3 9/M2 (when dried) to form a front barrier layer on the recording layer. The front barrier layer was then calendered to smooth its surface. An acrylic adhesive agent was applied to the reverse side of the support

to form an adhesive layer thereon. A silicone-resin-coated disposable backing sheet was then attached to the adhe- 15 sive label according to the invention.

Using a commercially available thermal printer having a thermal head, thermal printing was performed on the thermosensitive recording adhesive label. As a result, clear black images were formed on the adhesive label with a fluorescent orange background to give a well recognizable contrasting effect. 20 Example 1-2

The procedure of Example 1-1 was repeated except that the fluorescent dye composition dispersion, Liquid C, employed in Example 1-1 was replaced by 300 parts by weight of a fluorescent dye composition made by preparing a 50% aqueous dispersion of a solid solution of 25 Rhodamine B and acrylic resin.

Thermal printing was performed on the resultant label. As a result, clear black images were formed on the adhesive label with a fluorescent orange background having a marked recognition effect.

30 Example 2A

Liquids A and B were prepared in the same manner as described in Example 1-1.

Parts of Liquid A and 400 parts of Liquid B were mixed and dispersed to give a coating composition which was coated onto a sheet of commercially available high quality paper (basis weight 52 g/M2) at a coating rate of 5 g/M2 (when dried) to form thermosensitive colouring 35 layer 2a on the paper. - A mixture of the following components was dispprsed in a ceramic ball mill to give a coloured layer coating composition (Liquid F).

Liquid F Parts 40 Carboxyl-group-modified polyvinyl alcohol 50 Urea-formaldehyde resin filler 10 Polyamide epichlorohydrin resin 5 Water 500 45 50% aqueous dispersion of pulverized fluorescent dye composition (solid solution of Rhodamine Dye and acrylic resin) 10 5Q The resultant composition was coated onto the thermosensitive colouring layer at a rate of 7 g/M2 (when dried) to form a coloured layer on the thermosensitive colouring layer. The coloured layer 2c was then calendered to smooth it.

An acrylic adhesive agent was applied to the reverse side of the support to form an adhesive layer thereon and a silicone-resin-coated disposable backing sheet 6 was attahced to the adhe- 55 sive layer 5.

Using a commercially available thermal printer having thermal head, thermal printing was performed on the thermosensitive recording adhesive prepared prepared above. As a result, clear black images were formed on the adhesive label with fluorescent orange background having a marked recognition effect. 60 Example 2B

Liquids A and B were prepared in the same manner as described in Example 1-1.

Parts of Liquid A and 400 parts of Liquid B were mixed and dispersed and the resultant coating composition was coated onto a sheet of commerically available high quality paper (basis 65 8 GB2192288A 8 wieght of 52 g/M2) at a coating rate of 10 9/M2 (when dried) to form thermosensitive colouring layer on the paper.

A mixture of the following components was dispersed in a ceramic ball mill to form a coloured layer coating composition containing a coloured fluorescent dye composition (Liquid G).

5 Liquid G Parts 50% aqueous dispersion of pulverized fluorescent dye composition (solid solution of Rhodamine Dye and acrylic resin) 300 10% aqueous solution of polyvinyl 10 alcohol 50 The thus prepared coating composition was coated onto the thermosensitive colouring layer at a coating rate of 5 9/M2 (when dried) to form a coloured layer on the thermosensitive colouring layer. 15 A barrier coating composition (Liquid H) was prepared. This was the same as Liquid D employed as first barrier layer coating composition in Example 1-1; The coating composition (Liquid H) was coated onto the coloured layer at a coating rate of 3 99/M2 (when dried) to form a barrier layer on the coloured layer. The barrier layer was then calendered to smooth it. 20 An acrylic adhesive agent was applied to the reverside side of the support to form an adhesive layer thereon. A silicone-resin-coated disposable backing sheet was then attached to the adhesive layer.

Using a commerically available thermal printer having a thermal head, thermal printing was performed on the thermosensitive recording adhesive label. As a result, clear black images were 25 formed on the adhesive label with a fluorescent orange background having a marked recognition effect.

Example 2c

Liquids A and B were prepared in the same manner as described in Example 1-1. 100 Parts 30 of Liquid A and 400 parts of Liquid B were mixed and dispersed and the resulting coating composition was coated onto a sheet of commerically available high quality paper (basis weight of 52 9/M2) at a coating rate of 10 9/M2 (when dried), to form a thermosensitive colouring layer on the paper.

A barrier layer coating composition (Liquid 1) was prepared, which has the same as Liquid D 35 employed as the front barrier layer coating composition in Example 1-1.

This coating composition (Liquid 1) was coated onto the thermosensitive colouring layer at a coating rate of 3 g/m2 (when dried), to form a barrier layer on the colouring layer.

A coloured fluorescent dye composition (Liquid J) was prepared, which has the same as Liquid G employed as the coloured layer coating composition in Example 2B. 40 This coating composition (Liquid J) was coated onto the barrier layer at a coating rate of 3 9/M2 (when dried), to form a coloured layer. The coloured layer was then calendered to smooth An acrylic adhesive agent was applied to the reverse side of the support to form an adhesive layer thereon. A silicone-resin-coated disposable backing sheet was attached to the adhesive 45 layer.

Using a commercially available thermal printer having a thermal head, thermal printing was performed on the resulting thermosensitive recording adhesive label. As a result, clear black images were formed on the adhesive label with a fluorescent orange background having a marked recognition effect. 50 Example 3

A coloured layer coating composition (Liquid F) was prepared, which was the same colour layer coating composition as that employed in Example 2A.

The coating composition (Liquid F) was coated onto a sheet of commercially available high 55 quality paper (basis weight of 52 9/M2) at a coating rate of 7 9/M2 (when dried) to form a coloured layer on the paper.

Liquids A and B were prepared in the same manner as described in Example 1-1. 100 Parts of Liquid A and 400 parts of Liquid B were mixed and dispersed and the resulting coating composition was coated onto the coloured layer at a coating rate of 10 9/M2 (when dried) to 60 form a thermo-sensitive colouring layer on the coloured layer.

The thermosensitive colouring layer was then calendered to smooth it.

An acrylic adhesive agent was applied to the reverse side of the support to form an adhesive layer thereon. A silicone-resin-coated disposable backing sheet was then attached to the adhe- sive layer. 65 9 GB2192288A 9 Using a commercially available thermal printer having a thermal head, thermal printing was performed on the resultant thermosensitive recording adhesive label. As a result, clear black images were formed on the adhesive label with a fluorescent orange background having a marked recognition effect, although the fluorescent orange background was less intense as compared with the thermosensitive recording adhesive label prepared in Example 2A. 5 Example 4-1

Liquids A and B were prepared in the same manner as described in Example 1-1.

A fluorescent dye composition dispersion (Liquid C) was prepared as described in Example 1-1. 10 Parts of Liquid A, 400 parts of Liquid B and 150 parts of Liquid C were mixed and dispersed. The resultant thermosensitive colouring layer coating composition was coated onto a sheet of commercially available high quality paper (basis weight of 52 9/m2) at a coating rate of 10 g/rn2 (when dried) to form thermosensitive colouring layer on the paper.

Then Liquid C was coated onto the thermosensitive colouring layer at a coating rate of 1.5 15 9/M2 (when dried), to form a coloured layer on the thermosensitive colouring layer.

The coating composition (Liquid H) was coated onto the coloured layer at a coating rate of 3 9/M2 (when dried) to form a barrier layer on the coloured layer.

An acrylic adhesive agent was applied to the reverse side of the support to form an adhesive layer thereon. A silicon-resin-coated disposable backing sheet was then attached to the adhesive 20 layer:

Using a commercially available thermal printer having a thermal head, thermal printing was performed on the resulting thermosensitive recording adhesive label. As a result, clear black images were formed on. the adhesive label with a fluorescent orange background having a remarkable recognition effect. 25 Example 4-2

The procedure of Example 4-1 was repeated except that Liquid C was replaced by 300 parts by weight of a 50% aqueous dispersion of a pulverized fluorescent dye composition (solid solution of Rhodamine Dye and acrylic resin) having an average particle size of 1.8 pm (Liquid K). 30 Thermal printing was performed on the resultant thermosensitive recording adhesive label. As a result, clear black images were formed on the adhesive label with a fluorescent orange background having a remarkable recognition effect.

Example 4-3 35 The procedure of Example 4-2 was repeated except that the coloured layer coating compo- sition (Liquid K) was replaced by the following dispersion (Liquid L) which was prepared by dispersing the following components in a ceramic ball mill until the average particle size of the solid components became 20pm.

40 Liquid L Pulverized fluorescent dye composition (solid solution of Rhodamine Dye and acrylic resin) 100 45 Calcium carbonate 100 10% aqueous solution of polyvinyl alcohol 150 Water 150 5@ Using a commercially available thermal printer having a thermal head, thermal printing was performed on the resultant thermosensitive recording adhesive label. As a result, clear black images were formed on the adhesive label with a fluorescent orange background having a remarkable recognition effect.

A thermosensitive recording material having a thermosensitive recording layer of the previously 55 mentioned Type 5 can be prepared in the same manner except that the overlaying order of the thermosensitive colouring layer and the coloured layer is reversed. Clear black images with a fluorescent orange background can be also obtained with a remarkable recognition effect.

Claims

CLAIMS 6Q

1. A thermosensitive recording material comprising a support and a thermosensitive recording layer formed on one side of said support in which the thermosensitive recording layer includes (i) a thermosensitive recording system capable of producing a colour upon the imagewise applica tion of heat thereto, and (ii) a coloured fluorescent dye composition.

2. A recording material as claimed in Claim 1, further comprising an adhesive layer provided 65 GB2192288A 10 on the reverse side of the support opposite the thermosensitive recording layer.

3. A recording material as claimed in Claim 2, further comprising a front barrier layer formed on the thermosensitive recording layer.

4. A recording material as claimed in Claim 2 or Claim 3, further comprising a disposable backing sheet attached to the adhesive layer.

5 5. A recording material as claimed in any one of Claims 2 to 5, comprising a reverse barrier layer formed between the reverse side of the support and the adhesive layer.

6. A recording material as claimed in any one of the preceding claims in which the thermosensitive recording system comprises a combination of a leuco dye and a colour developer therefor. 10

7. A recording material as claimed in any one of Claims 2 to 6, in which the adhesive layer includes a pressure-sensitive adhesive. 1

8. A recording material as claimed in any one of the preceding Claims, in which the coloured li! fluorescent dye composition forms from 15 to 50 wt.% of the weight of the thermosensitive recording layer. 15

9. A recording material as claimed in any one of the preceding Claims, in which the fluorescent dye is orange.

10. A recording material as claimed in any one of the preceding Claims, in which the support is paper.

11. A recording material as claimed in any one of the preceding Claims, in which the 20 thermosensitive recording layer comprises a thermosensitive colouring layer comprising a thermo sensitive colouring system and,a binder resin, and a coloured layer comprising a coloured fluorescent dye composition and a binder resin, which layer are overlaid on the support.

12. A recording material as claimed in Claim 11, in which the coloured layer is formed on the thermosensitive colouring layer. 25

13. A recording material as claimed in Claim 11, in which the thermosensitive colouring layer is formed on the coloured layer.

14. A recording material as claimed in any one of Claims 11 to 13, further comprising a barrier layer between the thermosensitive colouring layer and the coloured layer.

15. A recording material as claimed in any one of Claims 11 to 14, in which the thermosen- 30 sitive colouring layer further comprises a fluorescent dye composition.

16. A recording materials as claimed in any one of Claims 11-14, in which the coloured fluorescent dye composition forms from 10 to 95 wt.% of the entire weight of the coloured layer.

17. A recording material as claimed in Claim 15, in which the coloured fluorescent dye 35 composition forms from 15 to 60 wt.% of the entire wieight of the thermosensitive colouring layer.

18. A recording material as claimed in Claim 1, substantially as hereinbefore described with reference to the Examples.

19. A recording material as claimed in Claim 1, substantially as hereinbefore described with 40 reference to the accompanying drawings.

Printed for Her Majesty's Stationery Office by Burgess & Son (Abingdon) Ltd, Dd 8991685, 1988.

Published at The Patent Office, 25 Southampton Buildings, London, WC2A 1 AY, from which copies may be obtained.