JPH0640176A - Transfer sheet for thermal transfer printing - Google Patents

Abstract

PURPOSE: To obtain a front surface of a film capable of writing with an aqueous ink and adhering a water activated adhesive by constituting a film of a rear surface of a crosslinked organic polymer of a reactive product of a polyalkyleneglycol with a multifunctional organic crosslinker reactive with an end hydroxyl group of the polyalkyleneglycol. CONSTITUTION: In the sheet to be transferred for a thermal transfer printing comprising a dye receiving surface 2 at one side and a support 1 carrying a rear surface film 4 at the other side, the film 4 is formed of a crosslinked organic polymer of a reactive product of a polyalkyleneglycol with a multifunctional organic crosslinker reactive with an end hydroxyl group of the polyalkyleneglycol. The film 4 contains no alkali metal salt. In this sheet, a surface which can be effectively written with an aqueous ink and adhered with water activated adhesive can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to thermal transfer printing.
nsfer printing); in particular, the present invention provides a backcoat that provides a surface that can be effectively written using water-based inks and to which a water-activated adhesive can be adhered. And a receiver.

[0002]

2. Description of the Related Art Thermal transfer printing is one
It is a general term for printing methods in which one or more heat transferable dyes are transferred from a dye carrying sheet (dye sheet) to a transfer receiver (receiver) in response to a thermal stimulus. Consisting of a dye-bearing coating that is uniformly spread over the entire print zone of the dye-bearing sheet and contains one or more heat transferable dyes, and a thin support bearing it Dye-carrying sheet is used to transfer the dye-carrying film to the transfer sheet (receiver sh
heating the selected, discrete area of the dye-carrying sheet while pressing it against the dye-receiving surface of (eet),
Printing can thereby be performed by transferring the dye to the corresponding zone of the transferred sheet. The shape of the transferred pattern is determined by the number and location of the discontinuous zones that are heated. Different colored dye
ecoat) can be used to produce a full color print by continuously printing in the same manner, and the multicolor dye-bearing coating is usually the same dye-bearing sheet. It is provided as an upper, repeated, discontinuous, uniform print size zone.

High resolution photographic prints are provided on any suitable printing device such as video, computer, electronic still camera (elect).
can be manufactured by thermal transfer printing using a programmable thermal print head or laser printer controlled by electronic signals derived from a ronic still camera) or similar signal generator. A typical thermal print head is, for example,
By providing a very short hot pulse according to the electronic signal, a row of individually operable miniature heaters is provided for printing 6 or more pixels per mm. Have.

The transferred sheet comprises a substrate having a dye receiving surface on one side. As such, for a support that is a dye-receptive polymer, the dye-receptive surface is
Simply, the surface of the support should have a particularly smooth surface texture (surface textu
re). However, in many cases, the transfer sheet comprises a support and a receiver coat supported by the support and comprising a dye-receptive composition; the transfer coating has an affinity for dye molecules. The dye molecules, which contain a permeable material, can readily diffuse into the transferred coating when a zone of the dye-bearing sheet that is pressed onto the transferred coating is heated during printing.

A variety of sheet materials can be used as the support; for example, cellulose fiber paper (usually with a polymer coating), thermoplastic films such as biaxially oriented polyethylene terephthalate film, pearl film (pearl).
film) and / or voided
Thermoplastic films or laminates of one or more of these sheets may be used.

Many transfer sheets have an image receiving surface of a support.
It also has one or more polymeric backside coatings on the side away from the (image-receiving side). This backside coating can be provided to serve a number of different roles;
The backcoat is provided to improve the handling property which allows one of the adjacent sheets to slide more easily over the other and prevent sticking of the sheets together. Good handling characteristics are particularly important in automatic printers that feed the transferred sheets from a cassette or stack of such sheets to a printing station one by one, and such improvement in handling characteristics is important. This is accomplished by providing an antistatic backside coating consisting of a crosslinked polymer matrix doped with an antistatic agent.

Alternatively or additionally, the transferred sheet has a textured surface (textured surface) for reducing blocking (adhesion).
surface); the matte surface is typically partly in a crosslinked polymer matrix, suitably a crosslinked polymer zone matrix doped with an antistatic agent as described above. It is formed by embedding a granular material. Examples of very effective antistatic backside coatings are described, for example, in EP-A409,526.

Photographic images obtainable by thermal transfer printing provide many photographic markets for versatile electronic imaging technology. That is, for example, an immediate printing capability is useful, for example, in an instant photograph booth, recording criminal or scientific evidence, or other occasional small-scale applications. Display and holiday notice postcard (h
Theoliday postcard can also take advantage of the ability to mix signals in electronic imaging, which can be used, for example, to double print a portrait on a prerecorded background. (sup
erimpose). In all of these applications and in other applications, the back surface of many conventional transfer sheets is hydrophobic and therefore incapable of receiving water-based inks and adhesives, which is very inconvenient for the user. It has become. For example, in the case of a passport photograph pasted on such a material, it is not possible to use an ordinary water-based ink to mark it on the back side (endorse), and we have found another means of writing letters etc. on the greeting card. Even so, you won't be able to put a postage stamp on it. These problems can occur in many known transfer sheets, whether the support surface is exposed or coated with a backside coating.

[0009]

The antistatic backside coating described in EP-A 409,526 consists of various crosslinked polymer matrices doped with alkali metal salt antistatic agents. The present inventor has now discovered that some (but not all) of the crosslinked polymer matrices described in the above European patent publications have good writability when using aqueous inks. It was found that it is possible to obtain a back coating having adhesiveness when an aqueous adhesive is used. Furthermore, the present inventors have surprisingly little, if any, a reduction in handling properties when the alkali metal salt is omitted by selecting a cross-linked polymer that gives good writing properties. (This is not the case for the other polymer matrices described in the above mentioned European patent publications) and the omission of such metal salts results in retransfer resistance.
It has been found that the surprising advantage of improved nce) is also obtained.

According to a first aspect of the present invention, a transfer sheet for thermal transfer printing comprising a support having a dye receiving surface on one side and a backcoat on the other side.
In the (receiver sheet), the backside coating is composed of a crosslinked organic polymer which is a reaction product of a polyalkylene glycol and a polyfunctional organic crosslinking agent reactive with the terminal hydroxyl group of the polyalkylene glycol, and the backside. A transfer sheet for thermal transfer printing is provided, wherein the coating does not contain an alkali metal salt.

First, the retransfer resistance (retransfer resist)
ance), dye diffusion thermal transfer (dye
Diffusion thermal transfer) is based on the fact that the dye has sufficient mobility to diffuse from one polymer system to another when heat is applied by the printer. Like the transferred layer (receiver layer), the backside coating is also usually based on a polymer, and when the backside coating contacts the dye-containing print for a long time, for example during storage,
Some retransfer of the dye can occur; in this case, the dye molecules forming the printed image rediffuse from the dye-receiving surface, retaining the dye-receiving surface during storage. , And transfer into the back surface coating of the adjacent transfer target sheet. This phenomenon occurs even under relatively low temperature ambient conditions and causes thermal transfer prints to be, for example, envelopes,
It is an undesirable side effect that is usually observed when stored in contact with each other in a wallet or box.

It is not clear why lithium salts and other alkali metal salts promote retransfer when used in the presence of crosslinked polyalkylene glycols, but in all compositions tested by the inventor. It was found that the tendency of retransfer to occur was reduced when the alkali metal salt was omitted.

Another surprising effect obtained by omitting the alkali metal salt is that when the polymer matrix is a cross-linked polyalkylene glycol, good handling properties are retained and usually there is less degradation of handling properties. Is easily observed. Even if the handling properties do not seem to be very good, no difficulty is found in automatically feeding from the roll of the transferred sheet and the resulting prints have convenient handling properties for the user. Was there. This has led to a great improvement in handling properties by adding lithium salts and other alkali metal salts, vinyl acetate, vinyl chloride and vinyl alcohol (VRO), which are particularly described in EP-A 409,526.
This was not found for the crosslinked terpolymer with H).

The preferred polyalkylene glycol for use in the present invention is polyethylene glycol. Although useful results are obtained when using polypropylene glycol, the moisture resistance decreases as this series progresses,
The strength of the coating is reduced. Polyethylene glycol is about 3
Molecular weights up to 5,000 (weight average molecular weight) are readily available, but in order to avoid coating problems that can occur when using polymeric materials, in the present invention about 10,000
It is preferred to use polyethylene glycol having an average molecular weight of less than or equal to about 2000 or less to maintain high levels of crosslinking. (
The term "about" means the manufacturer's inclusive range on both sides of the cited nominal numerical value. ) Polyethylene glycols of very low molecular weight, in particular diethylene glycol and triethylene glycol, are particularly suitable.

Conventional crosslinkers capable of reacting with the terminal hydroxyl groups of polyalkylene glycols are very reactive compounds, which generally have a low shelf life, but some may block their functional groups. . A readily available crosslinking agent that has been found to be particularly effective and convenient to use is a polyfunctional N- (alkoxymethyl) amino resin. Examples of polyfunctional N- (alkoxymethyl) amino resins include alkoxymethyl derivatives of urea, guanamine and melamine resins. Lower alkyl derivatives (ie, up to C ₄ butoxy derivatives) are commercially available and can be used effectively, but it is easier to remove more volatile by-products (methanol) later Therefore, the methoxy derivative is most preferable. An example of the latter, a methoxy derivative commercially available from American Cyanamid under the tradename Cymel under the tradename Cymel, is hexamethoxymethylmelamine, which is partially used to obtain a suitable viscosity. It is suitable to use in prepolymerized form (oligomer). Hexamethoxymethylmelamine is 3- to 6-functional on the basis of steric hindrance from the substituents and is suitable for acid
For example, p-toluene sulfonic acid (PTSA) can be used to form highly crosslinked materials.

The preferred backside coating of the present invention has a textured surface, which is formed by embedding a particulate material having a particle size of 2-10 μm in a crosslinked polymer. . Granular material is a mixture of small and large particles-at least 90% of these particles are 2-3 μm and 7
Has a particle size range of ˜10 μm, and these particles are distributed between the two particle size ranges according to a ratio of small particles to large particles of 2: 1 to 1: 5. A suitable particulate material is Syloid 24 having an average diameter of about 2 μm.
4 (product of Grace) and silica particles such as Gasil EBN (product of Crossfield) having an average diameter of about 8-10 μm, but other particles such as alumina and granular polymeric materials are also as described above. It can be used as a mixture of various particles in the particle size range.

The present inventor has found that such a textured surf
ace), especially those using larger particle size particulate materials, have been found to improve tooth and provide writability with pencils and ballpoint pens. Such a matte surface has a winding property for a long web of a transfer target sheet during manufacturing.
It can also bring advantages to (winding property). Such roughness of the matte surface also helps reduce slippage as the transfer sheet is being transported by the printer during printing, and can be deposited before or after printing. When the sheet is cut, the cut transfer sheet slides on one sheet over the other (sli
The handling characteristics can be improved by promoting ding).

The ratio of particulate material to polymer matrix of the backside coating (which may include thermoplastic polymers in addition to cross-linked thermoset materials) can be varied over a wide range, but the beneficial effect is still there. can get. A suitable range is 0.5 to about 50% of the total polymer content of the composition. Compositions containing a sufficient amount are preferred because amounts less than 0.5% are less effective; the upper limit is determined by the strength required for the coating. If too much particulate material is added, the coating becomes brittle and the optimum amount will vary with the particulate material used. Increasing the amount of addition of particles having a small particle size will gradually give a matte finish and improve ink absorbability, while increasing the amount of addition of particles having a large particle size will cause roughness as described above. growing.

A particularly preferable transfer sheet has a backside coating having a satin surface and (a) is a cross-linked polymer which is a reaction product of a polyalkylene glycol and a polyfunctional N- (alkoxymethyl) amino resin. ) Essentially consisting of dispersed in the crosslinked polymer and in an amount of 0.5 to 50% by weight of the crosslinked polymer, of a granular material having a particle size of 2 to 10 μm.

The polymer composition may contain other polymeric materials which are thermosetting polymers or thermoplastic polymers; however, the writability and tackiness of the resulting backcoat are retained. In order to do so, it is preferred that the crosslinked polyalkylene glycol reaction product comprises about half or more of the polymer composition. Polymers that are particularly useful for improving the backcoat brittleness, especially those polymers that are useful when the backcoat is in a tightly wound roll are thermoplastic polymers such as polymethylmethacrylate. Is. However, unless specific properties are required to be improved for use in some applications, it is preferred that the components of the backcoating consist entirely of the cross-linking reaction product of a polyalkylene glycol, whereby the cross-linking reaction is The benefits provided by the product are maximized.

As mentioned above, retransfer is a problem that occurs in dye diffusion thermal transfer; this retransfer is caused by the dye being able to diffuse into the material being transferred and, thus, being diffused again from the material being transferred. To do. Therefore, retransfer is a problem not experienced in other types of thermal transfer processes; for example, sublimation transfer, where the dye vapor is condensed from the ambient atmosphere onto the dye receiving surface.
on transfer) or ink-carrying sheet (ink sheet) (in
k sheet) has an ink-containing coating (ink coat) in which a dye or pigment is dispersed in a meltable resin, and when the ink-containing coating is melted, the dye or pigment is Transfer method to transfer to the surface of the transferred material together with
(melt transfer) [often, mass transfer
r)] does not cause retransfer problems.

Since the dye diffusion thermal transfer method requires the ability of the dye to diffuse into the transferred material, most of the transferred materials used in the dye diffusion thermal transfer method are used in other thermal transfer methods as described above. Unlike the transferred material described above, a special transferred coating having such diffusion characteristics is provided. Such dye diffusion can be caused by a concentration gradient, and thus the resistance of the backside coating according to the present invention to the retransfer of dye molecules to the dye diffusion transfer method by providing a transferred coating. It is particularly suitable for a particularly adapted transfer sheet. Accordingly, the preferred transfer material of the present invention is provided by a transfer coating provided with a dye-receiving surface on a support, and the transfer coating comprises a material having an affinity for dye molecules. It is a material to be transferred which comprises a dye-receptive composition capable of diffusing dye molecules when contained and caused by a concentration gradient.

The transfer sheet according to the first aspect of the present invention is wound as a roll on a core in a cassette in which a transfer sheet having an appropriate length can be drawn out by a printer when necessary. It is particularly suitable for use in the form of long strips. Many of the transfer sheets of the present invention are cut into individual print size portions and sold as a stack of transfer members contained in cartridges compatible with self-feeding printers or refill packaging products (ref.
ill pack). However, in the latter case, it is preferred to select a transfer sheet whose backside coating polymeric material consists predominantly or preferably entirely of crosslinked polyalkylene glycols.

According to a second aspect of the invention, in order to be particularly adapted to a roll feeding device, it has a multiple-print length.
Provided is a transferred sheet in the form of an elongated strip that is rolled and packaged for use in a continuous feed thermal transfer printer. by this,
A precut sheet can be used when needed, without the need to slide one of the precut sheets over the other, and without sticking to the printer and blocking the printer. , And can be supplied to a printing station; and, once printing is done, the alkali metal salt antistatic agent is not present in the backside coating, which provides the advantage of low retransferability. To be
Furthermore, once thermal transfer printing is performed on the transfer target,
In the back coating of the present invention, it is possible to write on the back surface of the printed matter with a water-based ink immediately after the printed matter leaves the printer or at any time thereafter.

According to a third aspect of the present invention, a dye receptive surface is provided by a dye receptive composition, and the transferred material is printed by dye diffusion thermal transfer, so that the dye receptive Provided is a transfer sheet, characterized in that the composition contains a transferred image-forming dye dispersed in the composition.

The present invention will be further described with reference to the drawings.

The transfer sheet shown in FIG. 1 has a support 1 made of a biaxially stretched polyethylene terephthalate film. One side of the support (ie, the dye receiving surface side) is coated with a conductive undercoat 2. On the surface of the underlayer coating 2, a receptive layer 3 is coated. The backside coating 4 of the present invention is coated on the opposite side of the dye receiving surface.

In FIG. 2 there is shown a strip 21 of the transfer sheet shown in FIG. 1; this strip is wrapped around a core 22 in a printer equipped with a continuous transfer body feeding device. It forms a roll 23 suitable for use.

[0029]

The invention is illustrated by a series of transfer sheets made using various coating compositions; these transfer sheets are cut lengths of those shown in the drawings. In each of the examples other than Example 2, a large web of milky white Melinex 990 biaxially oriented polyester film (ICI) was used as the support. The backside coating was applied first, followed by the conductive underlayer coating, and the transferred layer was applied thereon.

Examples 1 and 1a The web was coated with a backside coating as the first coating. Chemically etch one side of the web to create a mechanical anchorage (k
ey). In Example 1, a back coating composition was prepared from the following components: Digol 5.7 parts by weight Cymel 303 15 〃 〃 Amin-block PTSA 10 〃 〃 Diacon MG102 22 〃 Gasil (Gasil) EBN 2 〃 〃 Syloid 244 8 〃 〃 (Gasil EBN and Syloid 244 are
Diakon MG102 is a trademark of Silica Particles commercially available from Grace and Grace, Inc. and Diakon MG102 is polymethylmethacrylate commercially available from ICI. The backcoat coating compositions were prepared as two liquids; these are filler dispersions containing a thermosetting precursor solution and an acid catalyst. Immediately before use, the two liquids were mixed to obtain the above composition. This composition was mechanically applied to the above-etched surface, dried, and cured to form a backside coating having a thickness of 1.5-2 μm.

For the transferred layer side of the support, a conductive underlayer coating composition comprising the following components was prepared: Methanol (solvent) PVP K90 20 parts by weight Cymel 303 40 〃 〃 K-Flex (K-Flex) ) 5 〃 〃 Digol 15 〃 〃 PTSA 20 〃 〃 LiOH H ₂ 0 3.2 〃 〃 (K-Flex is a polyester polyol commercially available from King Industries, PVP is polyvinylpyrrolidone; both are suitable for coating. This composition is added to adjust.) This composition was first prepared as a separate solution containing the reactive components and mixed just before use. This solution was then machine coated onto the side of the support opposite the backside coating, dried and then cured at 110 ° C. to form a dry coating of about 1 μm thickness.

Cymel also in the coating composition for the transferred layer
An acid catalyst system compatible with 303 and a conductive undercoat was used; its composition is as follows: Toluene / MEK 60/40 solvent mixture Vylon 200 100 parts by weight Tegomer HSi 2210 0.7 〃 〃 Cymel 303 1.4 〃 〃 Tinuvin 900 1.0 〃 〃 Nacure 2530 0.2 〃 〃 (Tegomer HSi 2210 can be crosslinked with Cymel 303 under acidic conditions to form an effective release system during printing, Goldsc
A bis-hydroxyalkyl polydimethylsiloxane commercially available from Hmidt. ) This coating composition is 3
Prepared by mixing functional solutions of seeds;
Is a solution containing a dye-receptive virion and a tinuvin UV absorber, a second solution is a solution containing a cymel crosslinker, and a third solution is a tegomeric silicone release agent, a tegomer and cymel A solution containing a Nacure solution for promoting cross-linking polymerization. The coating composition for the transferred layer was coated on the conductive undercoat layer using an in-line coating apparatus, dried and then cured at 140 ° C. to form a dye-receptive layer having a thickness of about 4 μm.

Test results for coated webs have shown that the highly crosslinked backside coating is stable to the solvents and temperatures used in coating the other two paints.

For Example 1a, a third component was included in the back coating composition, that is, a solution of lithium nitrate in an amount sufficient to provide 1 part by weight of lithium nitrate in the total composition. Another transferred web was prepared in the same manner as described above except that the transfer was performed.

The handling properties, writability and tackiness tests were performed as described below for Examples 1, 1a, 2 and 2a.

Example 2 The same procedure as in the previous example was repeated except that a transparent biaxially oriented polyester film was used instead of the milky white support. In each case, the support was first coated with a backside coating on one side and then with a conductive underlayer coating on the other side; both of these had the same composition as in Examples 1 and 1a, respectively. Was there. However, the composition for the transferred coating was changed; the composition is as follows: Toluene / MEK 60/40 solvent mixture Byron 200 100 parts by weight Tegomer HSi 2210 1.37 〃 〃 Cymel 303 1.8 〃 Tinuvin 900 2.0 〃 〃 A comparative clear sheet was also prepared in the same manner as above, coated with Nacure 2530 0.2 〃 〃 transfer coating and then dried in the same manner as in Example 1 and containing lithium nitrate (see Example 2a). Example
Sheet samples obtained from 1,1a, 2 and 2a were evaluated.

Evaluation Test - Writability and Adhesive Each of the transfer target webs was cut into a standard size, and the deposit was supplied to a thermal transfer printer. A single sheet is fed sequentially from the deposit and a full color image
ge) was printed. There is no problem in handling during printing, and when the transfer sheet of Example 1 is changed to the transfer sheet of Example 1a or the transfer sheet of Example 2 is changed to the transfer sheet of Example 2a. , The degree of improvement in handling properties was substantially small.

A test for the writability of the printed matter was carried out using a pencil of hardness HB and a pen filled with a water-based ink. For both writing instruments, no difficulty was observed in writing with any of the above sets of transfer sheets.

In order to test whether such a transfer sheet can be used for postcards, a postage stamp was wetted and attached to the back coating. When dried, stamps do not peel off easily,
Damaged.

As a control, a commercially available transfer sheet having a standard crosslinked polymer back coating was printed in the same manner as described above. The pencil was able to write, but the water-based ink agglomerated, ran off, and the first dried ink did not leave a readable blob. These commercially available transfer sheets did not pass the post stamp test and fell off when dried.

Evaluation Test-Retransfer prints were deposited all face-up in the same manner, with the print side of one print overlaying the backside coating of the print resting on the print. The deposit was left for several days under the conditions of the accelerated aging test at 45 ° C. and 85% relative humidity. In the transfer-receiving sheets of Examples 1 and 2, extremely slight discoloration was observed on the backside coating. The transfer sheets of Examples 1a and 2a did not show any particular discoloration, but significant retransfer was observed.

Examples 3 to 9 and 3a to 9a The following tables show other back coating composition. These compositions were selected to show that a wide range of polyalkylene glycols can be used; these polyalkylene glycols range from high molecular weight to low molecular weight diethylene glycol, Includes polypropylene glycol and a series of polyethylene glycols. The percentages in the table are weight% based on the composition containing the antistatic agent (excluding the acid catalyst). In the preparation of the compositions of Examples 3-9, the polyalkylene glycol solution and the polyfunctional crosslinking agent solution were prepared separately and they were mixed in the same manner as in the above Examples immediately before use. In preparing the compositions of Comparative Examples 3a-9a, a solution containing an alkali metal salt was further prepared, which was mixed with the other two solutions immediately before use. In the tables below, the following abbreviations and trade names were used:

PPG stands for polypropylene glycol.
PEG represents polyethylene glycol. Trigor
gol) represents triethylene glycol. Digo
l) represents diethylene glycol. Triflate
late) represents lithium trifluoromethane sulfate. KFBS stands for potassium nonafluoro-1-butane sulfonate. PTSA represents p-toluenesulfonic acid (blocked with amine).

[0044]

The compositions shown in the table above provide the base polymer precursors used in the compositions, for the comparative examples antistatic agents and acid catalysts. If desired (and preferably), a filler dispersion may be added to the above composition when the solution is mixed immediately before the step of applying to the substrate to be transferred and then drying. The filler can be a mixture of the types as shown in Example 1 or a single type.

After printing, an attempt was made to write on the backside coating using an aqueous ink. There were practically no problems with any of the samples tested. Although the results of this test are too subjective to determine their value (quality) order for all samples, particularly good results were obtained when cross-linked diethylene glycol was used as the backside coating polymer. It is certain to be obtained. On the other hand, the uncoated Melinex 990 sheet could not be written using the same ink.

As in Examples 1 and 2, some of the samples were water-activated adhesive.
ive) was tested. The postage stamp (or its non-printed end strip) was wetted with water and crimped onto the backcoat. Adhesion was good in all samples.

When evaluated for retransferability, the results obtained showed that samples that did not contain alkali metal salts produced less retransfer than those that contained such metal salts.

Example 10 This example illustrates the use of particulate materials other than silica. When producing the transferred material web as described in Example 1, the transferred material layer and the antistatic inner layer were not changed, and a back coating composition having the following composition was used (this The composition was first applied, dried and then cured): PEG 600 38 parts by weight Cymel 303 38 〃 Pergopak M3 15 〃 Gasil EBN 5 〃 Phthalic acid 4 〃 Pergopak M3 is a finely ground urea manufactured by Martinswerk. It is a formaldehyde polymer and constitutes the entire particulate material.
However, some larger silica particles (Gasil EBN) were also included to give sufficient roughness to be effectively written using pencils and ballpoint pens. Since such a composition has good water wettability, a surface was obtained which was capable of good writing with a water-based ink and to which a water-activated adhesive could be applied.

[Brief description of drawings]

FIG. 1 is a schematic view of a cross section of a transfer sheet of the present invention.

FIG. 2 is a schematic view of a cross section of a roll of the transfer sheet of the present invention.

[Explanation of symbols]

 1 Support 2 Lower Layer Coating 3 Transferred Layer 4 Backside Coating 21 Transferred Sheet Strip 22 Core 23 Roll

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Lichyard Antony Hung United Kingdom. Suffolk. Ipswich. Woodstone Avenir. twenty two

Claims (11)

[Claims] 1. A transfer sheet for thermal transfer printing comprising a support having a dye receiving surface on one side and a backside coating on the other side, wherein the backside coating comprises polyalkylene glycol and Thermal transfer printing characterized by comprising a cross-linked organic polymer which is a reaction product of a terminal hydroxyl group of alkylene glycol and a reactive polyfunctional organic cross-linking agent, and wherein the back coating contains no alkali metal salt. Transfer sheet. 2. The transfer sheet according to claim 1, wherein the polyalkylene glycol is polyethylene glycol. 3. The transfer sheet according to claim 2, wherein the polyethylene glycol is selected from diethylene glycol and triethylene glycol. 4. The transfer sheet according to claim 1, wherein the cross-linked polymer of the back coating is an acid-catalyzed reaction product of polyalkylene glycol and a polyfunctional N- (alkoxymethyl) amino resin as a cross-linking agent. . 5. The transfer sheet according to claim 4, wherein the crosslinking agent is hexamethoxymethylmelamine or an oligomer thereof. 6. The transfer sheet according to claim 4, wherein the back surface coating is formed into a satin-like shape with a granular material embedded in a cross-linked polymer. 7. The back coating comprises (a) a crosslinked polymer which is a reaction product of a polyalkylene glycol and a polyfunctional N- (alkoxymethyl) amino resin, and (b) a crosslinked polymer dispersed and crosslinked in the crosslinked polymer. 0.5 of polymer
Transfer sheet according to claim 4, consisting essentially of an amount of 50% by weight of a granular material having a particle size of 2 to 10 µm. 8. The granular material is a mixture of small particles and large particles.
At least 90% of these particles are 2-3 μm and 7-10 μm
7. having a particle size range of m and these particles are distributed between the two particle size ranges according to a ratio of small particles to large particles of 2: 1 to 1: 5. The transfer sheet according to claim 7. 9. The dye-receptive surface is provided by a transferred coating carried on a support, and the transferred coating is a material having an affinity for dye molecules and by a concentration gradient. 2. A dye-receptive composition containing a material capable of diffusing dye molecules when it occurs.
The transfer sheet according to any one of 1 to 8. 10. A length for performing multiple printing,
A transfer sheet according to any of claims 1 to 8 having the form of an elongated strip that is rolled and packaged for use in a thermal transfer printer. 11. A dye-receptive surface is provided by a dye-receptive composition, and a transferred material is printed by dye diffusion thermal transfer, such that the dye-receptive composition diffuses into the composition. The transfer sheet according to any one of claims 1 to 8, which contains the transferred image forming dye.