JPH0254239B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multicolor thermal transfer recording paper. More specifically, the present invention relates to a method for producing multicolor thermal transfer recording paper using microcapsules containing heat-melting inks having different melting points.

In recent years, thermal transfer recording methods, which have advantages such as post-recording stability, tamperability, and solvent resistance, have been put into practical use compared to thermal recording methods that use thermal recording devices such as thermal printers and thermal facsimiles. . This is called thermal transfer recording paper, and it has a heat-melting ink layer on a support.The ink layer side is overlapped with plain paper, and heat from a thermal head such as a thermal facsimile machine is used to convert the thermal transfer recording paper to ordinary paper. Recording is performed by transferring ink onto paper.

Single-color thermal transfer, such as black, has already been put into practical use. Furthermore, research has shifted from single-color thermal transfer to multi-color transfer, and various publications can be found here.

For example, in Japanese Patent Application Laid-Open No. 57-182488, a thermal transfer ink layer coated on a base paper has three primary color ink layers of red, blue, and yellow, and a black color corresponding to each set of three primary color ink layers. There are some that are formed with an ink layer.

In JP-A-57-182489, a set of ink layers of a plurality of different colors is formed, and the area occupied by each ink layer in the set is set in proportion to the frequency of use.

Furthermore, Japanese Patent Laid-Open No. 57-182490 discloses a method in which a plurality of ink layers of different colors are arranged along the sub-scanning direction.

However, when performing transfer recording, the exemplified method not only complicates the recording system and conveyance drive system of the apparatus in order to match the color to be transferred to the corresponding color portion of the thermal transfer recording paper, but also The disadvantage is that it is difficult to cope with higher speeds.

On the other hand, as an improvement over the above cited example, JP-A-57-187296 discloses that a transfer layer containing transfer capsules of at least three primary colors of red, blue and yellow is formed on the main surface of the base paper, Some capsules have different melting points.
This publication states that transfer images of each color can be obtained by simply controlling the temperature of the heating head, and that the apparatus can be simplified.

However, microcapsules containing heat-melting ink have the drawback that the capsule wall is hardly destroyed even under high applied voltage, and the transferred image is insufficient.

In order to solve these drawbacks, the present inventors
As a result of extensive research, we discovered that by mixing microcapsules containing heat-melting inks consisting of three primary colors of magenta, cyan, and yellow with different melting points, coating the mixture on a support, and then applying pressure.
By destroying the microcapsules, it was possible to provide a multicolor thermal transfer recording paper capable of obtaining multicolor transfer images only by controlling the temperature of the heating head.

According to the present invention, by applying pressure after applying the microcapsules, the surface of the heat-melting ink layer can be made into a highly smooth surface, and the adhesion to plain paper can be improved. There is.

In addition, the microcapsules of the ink are magenta,
Although the three primary colors of cyan and yellow are isolated from each other, the walls of the microcapsules are destroyed, which has the advantage that they can be easily transferred onto plain paper using a heat-generating head. Furthermore, since the isolated microcapsules are transferred to the surface of plain paper as fine halftone dots due to the unique melting point difference of each ink, there is an advantage that a clear transferred image can be obtained.

Furthermore, when the microcapsules are prepared in an aqueous dispersion system, there is an advantage that multicolor thermal transfer recording paper can be easily produced in large quantities by one coating in the form of an aqueous dispersion.

The present invention will be explained in detail below.

The microcapsules containing heat-melting inks of magenta, cyan, and yellow having different melting points according to the present invention are coated irregularly on a support, and for example, the melting points of each ink are arranged in the order of magenta, cyan, and yellow. Suppose you set it to be high. When attempting to transfer a magenta image part on a multicolor image original, the magenta recording signal in the image signal is heated to the low melting point of magenta ink in a heat-generating head and transferred to thermal transfer recording paper. The destroyed magenta microcapsules on the painted surface can be easily transferred onto the plain paper surface. Similarly, cyan and yellow can also be transferred depending on the difference in melting point.

Here, the microcapsules of each of the three primary colors are irregularly scattered on the surface of the coating layer, and the thermally transferred plain paper surface is expressed as halftone dots.

In the hot melt ink according to the present invention, magenta,
The range of melting points of the three primary colors cyan and yellow is at least 10°C or higher, preferably 20°C or higher.

Next, the constituent materials of the multicolor thermal transfer recording paper according to the present invention will be explained.

As a support, it is best to use a thin one due to transfer characteristics.
Papers such as capacitor paper and glassine paper with a thickness of 30 μm or resin films such as polyester, polyimide, polycarbonate, and Teflon are used.

Heat-melting ink mainly consists of waxes, low-melting point resins, coloring materials, and softeners, and is obtained by sufficiently dispersing and mixing these components. Examples of waxes include paraffin wax, microcrystalline wax, beeswax, spermaceti wax, serrata wax, carnauba wax, candelilla wax, montan wax,
Low molecular weight polyethylene wax or the like is used.

Examples of low melting point resins include ethylene/bicopolymer, ethylene/acrylate copolymer, butadiene/styrene copolymer, vinyl acid/vinyl chloride copolymer, polyvinyl acid, rosin and rosin derivatives, petroleum resin, etc. is used.

As the coloring material, commonly used inorganic pigments, organic pigments, or dyes may be used for magenta, cyan, and yellow.

As the softener, for example, oleic acid, castor oil, dioctyl phthalate, liquid paraffin, or mineral oil can be used.

Next, the microencapsulation method for encapsulating the hot melt ink may be any method known in the art, such as complex coacervation method, interfacial polymerization method, in situ polymerization method, and spray drying method. etc. can be mentioned.

The multicolor thermal transfer recording paper of the present invention can be produced by coating the entire surface of the support using a general coater such as an air knife coater as an aqueous dispersion coating solution, or by coating dried microcapsules in an organic solvent. Examples include a method in which the agent is dispersed in water and coated on the entire surface or a portion of the support using a flexo printing machine, a gravure printing machine, or the like.

Examples of pressurizing methods for coated paper coated by the above-mentioned methods include methods such as super calender, machine calender, and gloss calender.

Furthermore, in addition to the microcapsules encapsulating magenta, cyan, and yellow heat-melting inks in the present invention, microcapsules encapsulating black or other color inks may also be added as appropriate.

Hereinafter, the present invention will be specifically explained with reference to Examples. Note that "parts" in the examples indicate parts by weight.

Example (1) Microcapsules containing magenta heat-melting ink were produced as follows.

(a) Composition of magenta ink with a melting point of 50°C Magenta pigment 10 parts Paraffin wax (MP50°C) 30 parts Castor oil 5 parts Petrozine (petroleum resin) 5 parts Mix each of these ingredients while melting until uniform. I made magenta hot melt ink.

(b) Microencapsulation 80 parts of the magenta ink prepared in (a) above is added to 100 parts of a 5% aqueous solution with a pH of 4.0 in which a styrene-maleic anhydride copolymer is dissolved with a small amount of sodium hydroxide and heated to 60°C. After melting at 60℃ in advance and dispersing, the emulsified particles are about 4
It was emulsified to ~5μ.

When 10 parts of melamine, 25 parts of a 37% formaldehyde aqueous solution, 65 parts of water, and a small amount of sodium hydroxide were added and heated to 60°C, the mixture became transparent in 15 minutes and a melamine-formalin initial condensate was obtained. Add this initial condensate to the emulsion, and
Microencapsulation was completed by continuing heating at 60°C for 3 hours. The average particle size of the microcapsules obtained was 5 to 6 μm, and the solid content of the microcapsule dispersion was 45%.

(2) Microcapsules containing cyan heat-melting ink were prepared as follows.

(b) Composition of cyan ink with a melting point of 65°C Cyan pigment 10 parts Paraffin wax (MP65°C) 80 parts Castor oil 5 parts Petrosine 5 parts Mix these ingredients until homogeneous while melting and heat melt the cyan. I made ink.

(b) Microencapsulation Microencapsulation was performed in the same manner as in (b) of (1) above. However, each temperature was 75°C, and the time required for encapsulation was 25 hours.

(3) Microcapsules containing yellow heat-melting ink were prepared as follows.

(b) Composition of yellow ink with a melting point of 80°C Yellow pigment 10 parts Carnauba wax (MP80°C) 80 parts Castor oil 5 parts Petrosine 5 parts These ingredients are mixed until homogeneous while melting to make yellow hot melt. I made ink.

(b) Microencapsulation was performed in the same manner as in (b) of (1) above. However, each temperature was raised to 90℃,
The time required for encapsulation was 2 hours.

(4) Multicolor thermal transfer recording paper was produced as follows. A 30% aqueous solution consisting of 30 parts each (solid content) of microcapsules containing the magenta, cyan, and yellow heat-melting inks obtained in (1) to (3) above and 10 parts of microcrystalline wax emulsion. The dispersion was applied to 26 g/m ² thin glassine paper using a Mayer bar at a dry coating weight of about 5 g/m ² . Using a super calendar, we applied a pressure of 10 kg/cm ² to the coated paper obtained to destroy the microcapsules on the coated surface and at the same time make the coated paper smooth, producing the desired multicolor thermal transfer recording paper. was able to be created.

The coated surface of this multicolor thermal transfer recording paper was overlapped with plain paper and printed with applied energy corresponding to the melting points of magenta, cyan, and yellow inks using a facsimile tester manufactured by Matsushita Electronic Components. A multicolor thermal transfer record with clear color halftone dots was created.

Comparative Example In the above example, printing was performed using a facsimile tester manufactured by Matsushita Electronics Components Co., Ltd. using coated paper that did not destroy the microcapsules. It was not destroyed by the applied energy and at the same time no transfer occurred.

Claims (1)

[Claims] 1. Microcapsules encapsulating heat-melting inks of three primary colors of magenta, cyan, and yellow having different melting points are mixed, coated on a support, and then pressurized to destroy the microcapsules. A method for producing multicolor thermal transfer recording paper.