JPH06262866A - Melt transfer ink image receiving sheet - Google Patents

Abstract

PURPOSE:To provide a melt transfer ink image receiving sheet good in dot reproducibility and obtaining high recording density. CONSTITUTION:A melt transfer ink image receiving sheet has a sheet like support, the undercoat layer (coating amt.; 8g/m<2>) formed on one surface of the support and the ink image receiving layer (coating amt.; 4g/m<2>) formed on the undercoat layer and based on a resin and pigment. The undercoat layer is characterized by containing wax and/or a rosin compd. and, pref., smoothing treatment due to a super calender is applied to the undercoat layer after the image receiving layer is formed to set the Oken smoothness of the undercoat layer to 1000sec.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a melt transfer type ink image receiving sheet. More specifically,
The present invention relates to a melt transfer type ink image-receiving sheet which, when used in a melt transfer type heat transfer printer using a thermal head, has good dot reproducibility and can receive an excellent print ink image having a high recording density. .

[0002]

2. Description of the Related Art The thermal fusion transfer recording method using a thermal transfer ink sheet and a thermal head is widely used in printers such as word processors and facsimiles because of its simple mechanism and easy maintenance. As a sheet (hereinafter referred to as an image receiving sheet), high-quality paper has been used. However, in recent years, due to full-color thermal transfer recording, in order to obtain higher gradation reproducibility than in the past, in printers, the size of each dot is changed from the conventional method of obtaining gradation without changing the size of one dot. It is changing to a dot variable system that changes the depth to obtain gradation. Therefore, in the image receiving sheet, in full color recording from low applied energy to high applied energy, dot reproducibility that faithfully reproduces the dot shape of the melt-transferred ink and recording density that transfers a sufficient amount of ink The height and the like are important items for recording quality.

As described above, it is necessary to appropriately deal with the characteristics of the image receiving sheet for full-color thermal transfer images. That is, in the case of plain paper for ordinary printing, the surface is too rough and the ink is not transferred in the transfer image,
That is, blanking occurs, or on the contrary, the surface is too smooth and the anchoring effect of the ink does not work, and the transferred ink is reversely transferred to the ink ribbon, which easily causes blanking. All of these gaps cause poor dot reproducibility. In addition to the decrease in the recording density due to the poor dot reproducibility as described above, the decrease in the recording density due to the low ink absorbability of the image receiving layer may occur.

In order to improve the transferability and adhesion of the ink, it is known to use a solid wax that is well compatible with the ink components together with the resin and pigment forming the ink image receiving layer (hereinafter referred to as the image receiving layer). (Japanese Patent Laid-Open No. 60-
110491). In this case, as the amount of wax contained in the image receiving layer increases, the gloss of the image receiving sheet increases,
In addition, the whiteness is lowered, and the naturalness peculiar to paper is impaired. Further, the writing property is deteriorated, the surface is easily scratched, and the coating film strength is deteriorated. Therefore, the amount of solid wax added to the image receiving layer is naturally limited.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned drawbacks of the prior art, and has good dot reproducibility even when used in a thermal transfer color printer, and provides good ink image recording with high recording density. It is intended to provide a transfer type ink image receiving sheet.

[0006]

Means for Solving the Problems As a result of intensive studies aimed at achieving the above object, the present inventors have found that an undercoat layer is provided between a sheet-shaped support and an ink image-receiving layer, and the undercoat layer has a wax. By including at least one selected from the above and a rosin compound, dot reproducibility becomes better than that of a thermal transfer ink image-receiving sheet consisting of a known resin component in recording by a fusion type thermal transfer printer, and high density recording is realized. In addition, it is possible to obtain a matte tone, less gloss, high whiteness, excellent writability, and a natural feeling like plain paper compared to a melt transfer type ink image receiving sheet containing a solid wax in the image receiving layer. The inventors have found out and completed the present invention.

The melt transfer type ink image-receiving sheet of the present invention comprises
A sheet-shaped support, an undercoat layer formed on one surface of the support, and an ink image-receiving layer formed on the undercoat layer and containing a resin and a pigment as a main component. The layer contains at least one selected from wax and rosin compounds.

[0008]

One of the reasons why the color density of a recorded image is increased by providing the undercoat layer containing a wax and a rosin compound in the image-receiving sheet of the present invention is that the wax and the rosin in the undercoat layer at the time of thermal transfer of ink. It is speculated that the thermal softening of the compound causes the ink ribbon and the image-receiving layer to come into close contact with each other, thereby improving the transferability of the ink. Further, as another reason, the ink contact-transferred to the image receiving layer, the ink that permeates the image receiving layer, the ink that cannot be received in the image receiving layer is contained in the undercoat layer between the image receiving layer and the support,
Receiving with a rosin compound or wax having high adhesiveness to the thermal transfer ink, thereby improving transferability and holding property of the ink, and good compatibility of the wax and the rosin compound with the ink, It is presumed that the ink is completely absorbed and received, which improves the transferability of the ink and improves the dot reproducibility.

Examples of the wax used in the present invention include vegetable waxes such as carnauba wax, wood wax, and ivory wax, animal waxes such as beeswax, serratca wax and wool wax, petroleum waxes such as microcrystalline wax and paraffin wax, Synthetic wax such as oxidation wax, ester wax, low molecular weight polyethylene,
One kind selected from waxes such as fatty acid ester and fatty acid amide, or a mixture of two or more kinds can be used. In general, the melting point of the wax is 140 ° C. so that the ink is softened at the time of heat transfer and can be brought into close contact with the ink ribbon and the image receiving layer.
The following is preferable.

The rosin compounds used in the present invention are rosin, hydrogenated rosin, and rosin ester. Rosin is obtained from pine trees and contains resin acids such as abietic acid, neoabietic acid, dehydroabietic acid, pimaric acid, isopimaric acid, levopimaric acid, sandaracopimaric acid, and parastophosphoric acid as main components. The hydrogenated rosin is obtained by hydrogenating the above rosin to dihydrogenate or tetrahydrogenate. Generally, rosin becomes colorless and stabilized at high temperature by hydrogenation.

The rosin ester is an ester of the above hydrogenated rosin. Specific examples include methyl ester, ethyl ester, glycerin ester (ester gum), diethylene glycol ester, and pentaerythritol ester of hydrogenated rosin. These rosin compounds can be used alone or in combination of two or more kinds, but they have a softening point of 2 because they need to be softened during heat transfer of ink to bring the ink ribbon and the image receiving layer into close contact with each other.
It is preferably 00 ° C or lower.

An ink image-receiving sheet for thermal transfer which does not have an undercoat layer containing a wax and / or a rosin compound has a property of adhesion between an ink ribbon and an image receiving layer due to softening of the undercoat layer during thermal transfer of ink. The recording density is lower than that of a thermal transfer ink image-receiving sheet having an undercoat layer containing a wax and a rosin compound, because the amount of ink that can be absorbed by the image-receiving layer is not transferred.

In the present invention, the undercoat layer comprises
In addition to the wax and / or the rosin compound, a binder resin may be mixed and used. As the binder resin, polyvinyl alcohol, oxidized starch, etherified starch, methoxycellulose, carboxymethyl cellulose, hydroxyethyl cellulose, casein, gelatin, soybean protein, polyvinylpyrrolidone, polyacrylamide, and water-soluble resins such as polyacrylic acid, and Vinyl chloride resin, vinyl chloride-vinyl acetate copolymer resin, vinylidene chloride resin, vinyl chloride-vinylidene chloride copolymer resin, acrylic ester copolymer resin, methacrylic ester copolymer resin, butyral resin, silicone resin, polyester resin , Non-water-soluble resins such as vinylidene fluoride resin, nitrocellulose resin, styrene resin, styrene-acrylic copolymer resin, styrene-butadiene copolymer, etc. are used to form a layer. The above water-insoluble resins may be used solutions, emulsions, or as a latex. These resins can be used alone or in combination of two or more.

A pigment may be added together with the wax and / or the rosin compound in order to improve the whiteness and opacity of the undercoat layer, or for matting. Examples of the pigment used together with the resin for forming the undercoat layer include zinc oxide, titanium oxide, calcium carbonate,
Inorganic pigments such as silicic acid, silicate, clay, talc, mica, calcined clay, aluminum hydroxide, barium sulfate, lithopone, titanium dioxide, zinc oxide, polystyrene, polyethylene, polypropylene, epoxy resin, melamine resin, phenol resin , Styrene-acrylic copolymer powders and beads, starch powders, cellulose powders, microspheres, hollow particles and the like, and these can be used alone or in admixture of two or more. In order not to impair the smoothness of the undercoat layer, the average particle size of the pigment used in the undercoat layer is preferably 5 μm or less.

In the present invention, the total amount of the resin (wax and / or rosin compound and binder resin) contained in the undercoat layer is in the range of 40 to 100% by weight based on the total solid weight of the undercoat layer. Preferably
The total amount of pigment is preferably in the range of 60 to 0% by weight. When the total content of the resin is less than 40% by weight, the ink absorbency of the obtained undercoat layer becomes insufficient, which may result in insufficient dot reproducibility and insufficient recording density, which is not preferable.

The solid content weight ratio of the total amount of the wax and / or rosin compound to the total amount of the other resins in all the above resins is preferably 10:90 to 100: 0. If the total amount of wax and rosin compound in all the resins is less than 10% by weight, the ink absorbency of the obtained undercoat layer may be insufficient, resulting in insufficient dot reproducibility and insufficient recording density. Is not preferred.

The solid content weight ratio of the total amount of all waxes and the total amount of all rosin compounds is 0: 100 to 90:
It is preferably 10. If the solid content weight ratio of the total amount of all waxes and the total amount of all rosin compounds deviates from this range, the balance between the adhesiveness and compatibility between the ink and the undercoat layer becomes poor, and the recording density becomes uneven and It is not preferable because the strength of the coating film may decrease.

Furthermore, the total amount of all waxes used in the undercoat layer is preferably 90% by weight or less of the total solid content of the undercoat layer, and the total amount of all rosin compounds is 80% of the total solid content of the undercoat layer. It is preferably not more than weight%. If the total amount of all waxes is more than 90% by weight, the coating strength of the obtained undercoat layer will be insufficient, which may cause a part of the image-receiving layer to be peeled off from the ink ribbon, resulting in defective recording. There is. If the total amount of all rosin compounds is more than 80% by weight, the adhesiveness between the image-receiving layer and the ink obtained will be too strong, resulting in poor peeling of the image-receiving layer from the ink ribbon and uniform dot formation. May result in poor recording properties or defective recording, which is not preferable.

The wax, rosin compound, other binder resin and pigment of the undercoat layer can be dispersed into a paint by a known method and apparatus.
That is, a liquid obtained by liquefying a wax, a rosin compound and other binder resins separately or simultaneously and a pigment or a pigment dispersion are mixed and dispersed to form a coating material.

The wax, rosin compound and other binder resins are liquefied by liquefying by heating to a temperature above the melting point of these resins or below a viscosity at which they can be sufficiently handled or liquefied with a solvent. Alternatively, it can be emulsified to form a dispersion liquid.

These liquefied wax, rosin compound, and other binder resin are mixed with a pigment or a pigment dispersion at a predetermined ratio, and in some cases, a suitable dispersing machine such as a stirrer or a sand grinder is used together with the dispersion medium. Can be mixed and dispersed to adjust the concentration, liquid state and the like.

To form the undercoat layer on the support, a usual coating method, that is, a Meyer bar method, a gravure roll method, a reverse roll method, a blade method,
A coating method such as a knife method, an air knife method, and a slit die method, and a drying and solidifying step may be used.

The image-receiving layer formed on the undercoat layer is formed by mixing the same binder resin and pigment that can be used with the wax and / or rosin compound of the undercoat layer as the image-receiving layer paint. It is obtained by using the same coating, drying and solidifying steps as the layer. Generally, in order to make the function of the image receiving layer sufficient, the coating amount of the image receiving layer coating after drying and solidification is preferably 4 to ²⁰ g / m ² .

The surface roughness of the image receiving layer is 15 according to Oken type smoothness.
The optimum time is from 0 second to 3000 seconds. If the smoothness of the image-receiving layer is less than 150 seconds, the adhesion between the ink ribbon and the image-receiving layer will be poor, and transfer defects of the image due to transfer defects may occur. The smoothness of the image receiving layer is 300.
If the time exceeds 0 seconds, the surface is too smooth and the anchoring effect of the ink does not work, and the ink transferred to the image receiving layer may be reversely transferred to the ink ribbon to cause missing of the image.

As the sheet-like support for coating the undercoat layer and the image receiving layer, paper such as high-quality paper and coated paper, woven cloth, non-woven cloth, polyester film, polypropylene film, polyethylene film, cellulose acetate film and other plastics can be used. Film, synthetic paper, etc. can be used.

A substrate having a better heat insulating property has a better dot reproducibility with the same printing energy, and an increase in recording density can be expected. Further, a support having a better heat insulating property requires less energy to obtain the same concentration and recording quality, and energy saving can be achieved. The heat insulation of the support is generally good in the order of clear film <quality paper <synthetic paper.

A coating layer may be provided on the high quality paper and an undercoat layer may be provided thereon in order to improve the unevenness of the side surface of the image receiving layer of the high quality paper and to improve the heat insulating property. This coating layer may contain a porous inorganic pigment or a hollow pigment in order to improve its heat insulating property.

The image-receiving sheet satisfying the above-mentioned conditions has a better dot reproducibility of an image and a higher recording density than that of a melt-transfer type ink image-receiving sheet which is composed of only known resins and pigments in recording by a thermal color printer. Increase can be realized.

[0029]

The present invention will be described in more detail with reference to the following examples, which should not be construed as limiting the invention. All "parts" in Examples and Comparative Examples are "parts by weight".

Example 1. An undercoat layer coating composition (1) having the following composition mixed with a stirrer was applied to one side of a high-quality paper having a basis weight of 80 g / m ² so that the coating amount after drying would be 8 g / m ^2, and then dried. Solidified to form an undercoat layer. Undercoat layer paint (1) Component weight part stabilized rosin ester emulsion (trademark: Super Ester 296 E-720, manufactured by Arakawa Chemical Industry, solid content 50%) Water 104

On the undercoat layer of the support, an image-receiving layer coating composition having the following composition mixed with a stirrer was applied so that the coating amount after drying was 4 g / m ² , dried and solidified to form an image-receiving layer. A layer was formed and subjected to a smoothing treatment with a super calender so that the Oken type smoothness of the image receiving layer was 1000 seconds to obtain a melt transfer type ink image receiving sheet. Image-receiving layer coating composition Weight part Styrene-butadiene copolymer (Trademark: L-1876, 100 manufactured by Asahi Kasei Kogyo, solid content 48%) Kaolinite clay dispersion (Trademark: Ultra White 90, 288 Engelhard, solid content 50) %) Water 12

Example 2. On one side of the same support as in Example 1, an undercoat layer coating material (2) having the following composition obtained by mixing with a stirrer was applied so that the coating amount after drying would be 8 g / m ^2, and drying Solidified to form an undercoat layer. Undercoat layer coating (2) Component Parts by weight Paraffin wax emulsion (trademark Hydrin P-7, 247 Chukyo Yushi, 30% solids) stabilized rosin ester emulsion (trademark: SUPER ESTER 148 E-720, Arakawa Chemical Industries Made, solid content 50%) Water 5

On the undercoat layer of the above-mentioned support, the same image-receiving layer coating material as used in Example 1 was applied so that the coating amount after drying would be 4 g / m ² , dried and solidified to form an image-receiving layer. Then, this was subjected to a smoothing treatment with a super calendar to obtain a melt transfer type ink image-receiving sheet so that the Oken type smoothness of the image-receiving layer was 1000 seconds.

Example 3. A barrier layer coating composition having the following composition obtained by mixing with a stirrer was applied to one side of the same support as in Example 1 so that the coating amount after drying was 3 g / m ² , dried and solidified to form a barrier. Layers were obtained. Barrier layer coating composition Weight part Polyvinyl alcohol (trademark: PVA-117, Kuraray, 43 solid content 94%) Water 357

On the barrier layer of the support, an undercoat layer coating material (3) having the following composition obtained by mixing with a stirrer while heating was applied so that the coating amount after drying was 8 g / m ^2.
It was applied at a temperature of 0 ° C., dried and solidified to form an undercoat layer. Undercoat layer coating material (3) Component weight part Hydrogenated rosin ester (trademark: Ester gum H, 400 Arakawa Chemical Industries, softening point 72 ° C.) The same image receiving layer as in Example 1 on the undercoat layer of the above support. The coating is applied so that the coating amount after drying will be 4 g / m ² , dried and solidified to form an image-receiving layer, which is then subjected to a smoothing treatment with a super calendar, and the Oken-type smoothness of the image-receiving layer is applied. Was 1000 seconds to obtain a melt transfer type ink image receiving sheet.

Example 4. The same barrier layer coating material as in Example 3 was applied to one surface of the same support as in Example 1 so that the coating amount after drying was 3 g / m ^2, and the coating was dried and solidified to form a barrier layer. The undercoat layer coating material (4) having the following composition obtained by mixing with a stirrer while heating was applied onto the barrier layer of the support at a temperature of 80 ° C. so that the coating amount after drying was 8 g / m ^2. The undercoat was applied, dried and solidified to form an undercoat layer. Undercoat layer coating material (4) Component Parts by weight Paraffin wax (TM: paraffin wax 135, 200 manufactured by Nippon Seiro Co., Ltd., melting point 58 ° C.) hydrogenated rosin ester (trademark: Ester Gum H, 200 Arakawa Chemical Industries, Ltd., softening point 72 ℃)

On the undercoat layer of the above support, the same image-receiving layer coating material as in Example 1 was applied so that the coating amount after drying would be 4 g / m ² , dried and solidified to form an image-receiving layer. Then, this was subjected to a smoothing treatment with a super calendar to obtain a melt transfer type ink image-receiving sheet so that the Oken type smoothness of the image-receiving layer was 1000 seconds.

Comparative Example 1. The same image-receiving layer coating material as in Example 1 was directly applied to one surface of the same support as in Example 1 so that the coating amount after drying was 4 g / m ^2, and dried and solidified to form an image-receiving layer. Then, this was subjected to a smoothing treatment with a super calendar to obtain a melt transfer type ink image-receiving sheet so that the Oken type smoothness of the image-receiving layer was 1000 seconds.

Tests The image-receiving sheets of Examples 1 to 4 and Comparative Example 1 were replaced with 20
After conditioning the humidity for 2 hours at 65 ° C and 65% RH, a commercially available thermal transfer color printer (trademark: CHC-445, manufactured by Shinko Denki Co., Ltd.)
The ink image was melt-transfer recorded and the performance was evaluated. The following method was used to evaluate the recording results.

(1) Dot reproducibility: Good reproduction of ink dots transferred from the ink ribbon to the image-receiving layer is indicated by ◯, and defective ink dots are indicated by x.

[0041]

[Table 1]

[0042]

According to the present invention, dot reproducibility is good,
It is possible to produce a melt transfer type ink image-receiving sheet that can obtain a high recording density, and it greatly contributes to the industrial world.

Claims (1)

[Claims] 1. A sheet-shaped support, an undercoat layer formed on one surface of the support, and an ink image-receiving layer formed on the undercoat layer and containing a resin and a pigment as main components. And the undercoat layer contains at least one selected from a wax and a rosin compound.