JPH0952448A - Heat-sensitive transfer medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-sensitive transfer medium, which has high sensitivity, fidelity and thermal responsiveness in transferring and, at the same time, large durability of the transferred image, especially abrasion resistance. SOLUTION: This heat-sensitive transfer medium, in which a hot melt ink layer 4 containing an aldehyde resin is provided on a base material 1 under the condition that a peel layer, the melting temperature of which is lower than that of the ink layer 4, is provided between the base material 1 and the ink layer 4. Preferably, an intermediate layer 3 is provided further between the peel layer 2 and the ink layer 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer medium used in a thermal transfer printer or the like.

[0002]

2. Description of the Related Art Thermal transfer, as is well known,
By superimposing the transfer medium (image-receiving paper) on the ink layer side of the thermal transfer medium (ink ribbon) having the heat-meltable ink layer on the substrate, and selectively heating from the substrate side with a thermal head or the like, This is a technique for forming a desired image such as characters and illustrations on a transfer medium. This technique is particularly suitable for personal use because it has the characteristics of quiet printing and low power consumption, and is widely applied to an output device attached to a word processor or a facsimile or a single thermal transfer printer.

As a heat-sensitive transfer medium used for heat-sensitive transfer,
The simplest method is to provide only one heat-fusible ink layer on the base material, but to improve the transferability to the image receiving paper with a rough surface and the durability of the transferred image A release layer may be provided on the surface (for example, JP-A-60-189492).
(See JP-A-60-189493), an adhesive layer is provided on the ink layer for the purpose of preventing the deviation between the ink ribbon and the image receiving paper (see, for example, JP-A-60-189493). Are known.

[0004]

The above-mentioned improvements are aimed mainly at improving the printing quality, but conventional thermal transfer media including such improved products generally have insufficient high-speed followability. There was a limit to the improvement of printing speed. That is, in order to perform clear printing at high speed, it is necessary that the transfer sensitivity, fidelity, and thermal response be high, and the durability of the transferred image is particularly high, and scratch resistance is high. There is no satisfactory thermal transfer medium. The present invention seeks to provide a thermal transfer medium that meets all of these requirements.

[0005]

The present invention provides a heat-sensitive transfer medium comprising a base material and a heat-meltable ink layer, wherein the ink layer contains an aldehyde resin, and the space between the base material and the ink layer is large. There is provided a heat-sensitive transfer medium, characterized in that a release layer having a lower melting temperature than the ink layer is provided on the above-mentioned ink layer, thereby solving the above problems.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION As a base material, thin paper such as glassine paper, tracing paper, condenser paper, synthetic resin film such as polyester film, and other conventionally used materials are similarly used. However, in order to improve the thermal response, it is preferable that the base material be as thin as possible and that the material has high thermal conductivity.
A thin polyethylene terephthalate (P having a thickness of about 2.5 to 6 μm (P
ET) film is preferably used.

The hot-melt ink layer contains a resin or wax as a binder, usually a pigment as a colorant, and optionally other additives. As the pigment, various conventionally known pigments such as carbon black and various organic pigments are used. Lubricating oils, pigment dispersants, softeners, leveling agents and the like are used as additives.

As the binder, the heat-meltable ink layer of the heat-sensitive transfer medium of the present invention contains an aldehyde resin. Aldehyde resin generally refers to a polymer of aldehyde, but here not only a homopolymer of aldehyde,
The concept includes copolymers of various aldehydes and copolymers of aldehydes with other monomer units. Therefore, the aldehyde resin which can be used in the present invention includes various conventionally known ones such as polyacetal which is a polymer of aldehyde, and amino resin obtained by the reaction of an aldehyde and an amino compound. Those having a condensed structure with urea are preferable. When the aldehyde resin is contained in the binder, the heat-fusible ink layer of the present invention becomes slightly tacky when melted, and therefore easily adheres to the transfer medium and is transferred quickly, and after transfer and solidification, it is not covered. It strongly adheres to the transfer medium and improves the scratch resistance of printing.

As the above-mentioned binder, in addition to the aldehyde resin, various resins and waxes commonly used in the present technical field are contained, if necessary. Examples thereof include thermoplastic resins such as ketone resins, polyvinyl acetate, polystyrene and acrylic resins, and waxes such as carnauba wax, candelilla wax, lanolin wax, paraffin wax and rice wax. Particularly, it is preferable to add a ketone resin because the scratch resistance of the transferred print can be improved. The mixing ratio of the aldehyde resin and the other resin, wax, etc. is appropriately selected so that the melting point of the heat-meltable ink layer is about 60 to 90 ° C. and the viscosity at the time of heating and melting is about 5 to 100 Pascal seconds. However, the aldehyde resin is usually 5 to 5 in the heat-meltable ink layer.
It is preferably contained in an amount of about 30% by weight.

The heat-meltable ink layer is provided on the base material via a release layer. The peeling layer melts at a lower temperature than the heat-meltable ink layer, and promotes peeling of the ink layer from the substrate.
In the present invention, the sensitivity, fidelity, and thermal response required for high-speed printing are ensured by the effect of attaching the heat-meltable ink layer to the transfer medium and the effect of releasing the release layer from the substrate. Further, since the peeling layer covers and protects the transferred ink layer after the transfer, it contributes to the improvement of the scratch resistance of printing in combination with the property of the ink layer itself.

The release layer contains waxes such as carnauba wax, microcrystalline wax, ester wax, paraffin wax and montan wax as a main component, and if necessary, a thermoplastic resin such as polyvinyl acetate, polystyrene and acrylic resin. , And those to which additives such as lubricating oil are added can be used. It is preferable that the melting point of the release layer is about 55 to 75 ° C., and the viscosity at the time of heating and melting is about 5 to 100 pascal seconds.

An intermediate layer is preferably provided between the hot-melt ink layer and the peeling layer. The intermediate layer has a role as a buffer zone for preventing the components of the heat-fusible ink layer and the components of the release layer from migrating and mixing with each other. The heat-meltable ink layer contains an aldehyde resin and needs to have relatively high tackiness when melted, while the peeling layer, on the contrary, needs to have relatively low tackiness. different. Therefore, when the heat-meltable ink layer is provided directly on the release layer, the components of both layers may migrate to each other during production or use, which may cause mixing. In such a case, by providing an intermediate layer as a buffer zone between both layers, it is possible to eliminate the above-mentioned mixing agitation.

Further, when the intermediate layer is constituted so as to melt at a temperature lower than that of the peeling layer, the composition of the peeling layer is adjusted so as to melt under the low speed printing condition, and when this is used under the high speed printing condition, the peeling layer is formed. Since it is possible to perform printing by melting the intermediate layer without melting, it is possible to perform excellent printing under both low speed printing conditions and high speed printing conditions. In that case, if the intermediate layer is made of a low-melting material and a filler, the intermediate layer will be destroyed if only the low-melting material is melted under high-speed printing conditions. It is suitable for printing.

The composition of the intermediate layer is selected so as to buffer the difference in composition between the heat-meltable ink layer and the peeling layer, but generally, polycyclic aromatic resin, aldehyde resin, ester wax,
Those containing paraffin wax and the like are preferable. Further, as mentioned above, extender pigment, carbon black, plastic particles (made of a resin that does not heat-melt such as silicon resin, fluororesin, melamine resin, urea resin, etc.), organic pigment, inorganic pigment, etc. may be added as a filler. preferable. In addition, if necessary, plasticizer, silicone oil,
Petrolite, polybutene (having fluidity) and the like can be added to the intermediate layer.

In order to form the release layer, the intermediate layer, and the heat-meltable ink layer on the substrate, solvent coating, hot melt coating, etc. can be used according to a conventional method.

[0016]

EXAMPLES prepare a heat-sensitive transfer medium of the present invention shown in Example Figure 1, was used in the heat-sensitive transfer.

(1) Formation of Release Layer 3 parts by weight of carnauba wax (melting point 87 ° C.) and 1 part by weight of polyethylene (melting point 80 ° C.) were mixed in a mixed solvent of 50 parts by weight of toluene and 10 parts by weight of isopropyl alcohol (IPA). It melt | dissolved and the coating liquid was obtained. This coating solution was applied on a polyethylene terephthalate (PET) film 1 having a thickness of 5 μm at a rate of 1.7 g / m ² and dried to form a release layer 2.

(2) Formation of Intermediate Layer 1 part by weight of an aldehyde resin (LALOPEARL A-81 manufactured by BASF, a condensation product of aldehyde and urea, melting point 80 ° C.) and 1 part by weight of polyvinyl butyral (melting point 90 ° C.) were added to IPA5.
It was dissolved in 0 part by weight to obtain a coating solution. 0.3% of this coating solution
It is coated on the release layer 2 at a rate of g / m ² and dried,
The intermediate layer 3 was formed.

(3) Formation of heat-meltable ink layer 10 parts by weight of black pigment, carnauba wax (melting point 87 ° C.)
5 parts by weight, aldehyde resin (LASF Pearl A manufactured by BASF)
-81, condensation product of aldehyde and urea, melting point 80 ° C) 1
One part by weight and 1 part by weight of a ketone resin (melting point 105 ° C.) were dissolved in 100 parts by weight of toluene and mixed to obtain a coating liquid.
This coating solution is coated on the above intermediate layer at a rate of ² g / m ² ,
The ink layer 4 was formed by drying. Thus, the thermal transfer medium according to the present invention was obtained.

Comparative Example A release layer 2 and an intermediate layer 3 were formed on a PET film substrate 1 in the same manner as in the above example. Next, 100 parts by weight of carnauba wax (melting point 87 ° C.), 50 parts by weight of paraffin wax (melting point 76 ° C.), 5 parts by weight of polyethylene wax (melting point 95 ° C.), and 20 parts by weight of black pigment are mixed while heating to form a coating liquid. Obtained. The coating liquid was applied onto the intermediate layer at a rate of ² g / m ² and dried to form an ink layer 4.

Evaluation Test Using the thermal transfer mediums obtained in Examples and Comparative Examples, a thermal transfer printer (KM706A manufactured by Anritsu Corporation) was used to change the printing speed to four levels of 4, 6, 8 and 12 inches / sec. Printed on paper. The obtained printed matter was visually evaluated in four grades of good (◯), normal (Δ), bad (x), and very bad (xx). Table 1 shows the results.

[Table 1] Printing speed (inch / sec) 4 6 8 12 Examples ○ ○ ○ ○ Comparative examples ○ △ × × ×

[Brief description of drawings]

FIG. 1 shows a preferred embodiment of the thermal transfer medium of the present invention.

[Explanation of symbols]

 1 Base Material 2 Release Layer 3 Intermediate Layer 4 Heat Melt Ink Layer

Claims (7)

[Claims] 1. A heat-sensitive transfer medium comprising a base material and a heat-meltable ink layer, wherein the ink layer contains an aldehyde resin, and the temperature of the melt temperature between the base material and the ink layer is higher than that of the ink layer. A thermal transfer medium characterized in that it is provided with a low release layer. 2. Further, between the release layer and the ink layer,
The heat-sensitive transfer medium according to claim 1, further comprising an intermediate layer for preventing the components of both layers from migrating and mixing with each other. 3. The thermal transfer medium according to claim 1, wherein the ink layer further contains a ketone resin. 4. The thermal transfer medium according to claim 1, wherein the aldehyde resin is a condensate of aldehyde and urea. 5. The thermal transfer medium according to claim 1, wherein the release layer contains wax as a main component. 6. The thermal transfer medium according to claim 2, wherein the melting temperature of the intermediate layer is lower than that of the peeling layer. 7. The thermal transfer medium according to claim 6, wherein the intermediate layer contains a low melting point material and a filler.