JPH02204092A - Heat sensitive transfer material and heat transfer recording - Google Patents

Abstract

PURPOSE:To obtain a heat sensitive transfer material in which no scum nor hairlike end is not caused even by a double density recording by specifying the fracture strength of an ink layer on a board in a specific range. CONSTITUTION:A heat sensitive transfer material 1 has an ink layer 1b on a board, and the fracture strength of the ink layer is 30 - 80kg/cm<2> at 25 deg.C. The ink layer 1b contains binder and colorant. The binder contains 40 - 80wt.% of ethylene-vinyl acetate copolymer, 20 - 60wt.% of wax, and the binder desirably further contains 5 - 15wt.% of tackifier. The material 1 and a material 2 to be recorded such as paper, etc. are superposed, heated by a recording head 3 such as a thermal head, etc., to transfer heat fusible ink of the material 1 to the material 2 to be recorded to obtain a recording image. In this case, when the fracture strength of the ink layer is specified to the above range, even if a double density recording is employed, no scum, no hairlike end nor an uneven end occurs, and a recording image having high clarity and high quality is obtained.

Description

[Detailed Description of the Invention] f Industrial Application Field] The present invention relates to a thermal transfer material used for thermal transfer recording, specifically,
The present invention relates to a thermal transfer material and a thermal transfer recording method that allow good recording to be obtained even if the amount of thermal transfer material used is reduced.

[Conventional technology]

In addition to the general features of thermal recording methods, such as the equipment used is lightweight, compact, noiseless, and has excellent operability and maintainability, the thermal transfer recording method does not require colored processed paper, and it also improves the quality of the recorded image. It has the feature of excellent durability and has been widely used recently.

This thermal transfer recording method uses a thermal transfer material in which a thermal transferable ink layer consisting of a colorant dispersed in a heat-melting binder is coated on a support, which is generally in the form of a sheet. By overlapping the thermally transferable ink layer so that it is in contact with the recording medium, and applying heat from the base material side using a thermal head to transfer the melted ink layer to the recording medium,
A transferred recorded image is formed on a recording medium according to a heat supply shape (pattern).

[Problem to be solved by the invention]

In conventional thermal transfer recording, the thermal transfer ink is almost completely transferred from the thermal transfer material to the recording medium with a single application of heat, so it is disposable, has high running costs, and can be kept confidential from the used thermal transfer material. There was also concern that the information would be leaked.

On the other hand, Japanese Patent No. 3,984,809, Japanese Patent Publication No. 57-83471, or Japanese Patent Publication No. 62-58917
A recording method (hereinafter referred to as double-density recording) has been proposed in which the amount of heat-sensitive transfer material used is reduced by providing a relative speed between the heat-sensitive transfer material and the recording medium. however,
Conventionally, this recording method has had the following problems.

The first problem is that background smudge (unnecessary ink transfer to a recording medium such as paper) occurs.

This occurs because in double-density recording, the thermal transfer material and the recording medium slide, so the ink layer of the thermal transfer material is scratched off the surface of the recording medium and transferred to the entire surface of the recording medium.

The second problem is that, as shown in FIG.
(hereinafter referred to as whisker-like ends). This occurs because in double-density recording, heat is applied multiple times to the same part of the ink layer, so the melt viscosity of the ink layer is extremely low, and the thermal transfer material and the recording medium slide. .

As a countermeasure against background stains, JP-A-60-178088 1.
- has an over-layer that does not contain a colorant in the ink layer -F, but the over-layer is transferred to the recording medium after heat is applied, so the problem of whisker-like edges cannot be solved. Not done.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a thermal transfer material and a thermal transfer recording method that do not cause background stains or whisker-like edges even during double-density recording.

[Means for Solving the Problems] The thermal transfer material of the present invention is characterized in that the breaking strength of the ink layer on the base material is in the range of 30 to 80 kg/enf at 25°C.

Further, the thermal transfer recording method of the present invention uses a thermal transfer material having an ink layer having a breaking strength of 30 to 80 kg/crrf at 25°C on a base material, and the recording medium is transferred to the recording head within the same time. The thermal transfer material is characterized in that the distance that the heat-sensitive transfer material moves relative to the recording bed is shorter than the distance that the heat-sensitive transfer material moves relative to the recording bed.

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

In the following description, "1%" and "1%" represent quantitative ratios.
Parts are by weight unless otherwise specified.

The thermal transfer recording method (double-density recording method) using the thermal transfer material of the present invention is, as shown in FIG. By heating with a recording head 3 such as the above, the heat-melting ink of the thermal transfer material 1 is transferred onto the recording medium 2, and a recorded image is obtained. The thermal transfer material I and the recording medium 2 are continuously moved in the directions of arrows A and B by the rotation of the capstan roller 12, the pinch roller 13, and the platen roller 11, respectively, and are transferred onto the recording medium 2 one after another. Recording is done. The capstan roller 12 and the pinch roller 13 are driven by a motor 14, and the platen roller 12 is driven by a motor 15, respectively. The transported thermal transfer material l is
It is wound up by a winding roller 10 driven by a motor 14. A spring 16 presses the recording head 3 against the platen roller 11 via the thermal transfer material 1 and the recording medium 2.

In FIG. 1, the thermal transfer material 1 and the recording medium 2 are moving in the same direction, but for example, by conveying the recording medium 2 in the direction opposite to the direction of arrow B, The recording medium 2 may be moved in the completely opposite direction.

Now, in this thermal transfer recording method, there is a relative speed between the thermal transfer material 1 and the recording medium 2. In the example shown in FIG. 1, the head 3 does not move, and the thermal transfer material 1 moves slower than the recording medium 2. In other words, when comparing the distance traveled by the thermal transfer material 1 and the distance traveled by the recording medium within the same time period, the distance traveled by the thermal transfer material 1 is shorter. As a result, in this recording method, recording is performed as shown in FIGS. 2 to 5.

As shown in FIG. 2, when the width of the heating element 3a of the recording head 3 in the thermal transfer material feeding direction (arrow A direction) is l, 1
The second heat application is applied to a totally unused thermal transfer material 1 with a magnitude of 1 (FIG. 2). Incidentally, the thermal transfer material 1 is a support l.
A heat-fusible ink layer 1b is provided on a.

However, when heat is applied for the second time, the recording medium 2 moves 7 in the direction of arrow B, while the thermal transfer material 1 moves 1N with respect to the recording head 3 (the value of N=50N in FIG. 2). depends on how many times the same part of the thermal transfer material 1 can be printed.
The part N)) which has already been subjected to heat application once will be used again (Fig. 3).

In this way, when heat is applied continuously in the lateral direction, the heat-sensitive transfer material that receives heat from the second time onwards has only 1N unused, and the remaining parts are applied several times in increments of 1, /N. Heat has already been applied (Figures 3 to 5). In other words, the thermal transfer material is in the same state as if the same location had been used N times, and moreover, it is moving while rubbing the surface of the recording medium.

In the above example, it is assumed that the thermal transfer material 1 is moved by 11N with respect to the recording head 3 during the second, third, etc. heat application, but the movement is less than 1 and more than J/N. If so, the thermal transfer material 1 can be saved. In the explanation below, an example was shown in which the recording head 3 does not move. However, even if the thermal head 3 moves, the moving distance of each of the thermal transfer material 1 and the recording medium 2 is calculated by the recording head. 3 as a reference and the distance from the recording head 3 can be considered in the same way as the example explained in FIGS. 1 to 5. In other words, in the thermal transfer recording method of the present invention, the thermal transfer material l is longer than the distance that the recording medium 2 moves relative to the recording head 3 within the same time
The distance traveled by the recording head 3 with respect to the recording head 3 is shorter.

Now, as is clear from the above description, the thermal transfer material 1 of the present invention is used while sliding on a recording medium such as paper, so if the breaking strength of the ink layer 1b is too small, Scratching with the surface may cause scumming or whisker-like edges, which is undesirable. Another ink layer! If the breaking strength of , b is too large, it becomes difficult to break well at the boundary between the heat application part and the specific heat application part of the ink layer 1b, resulting in poor cutting (the edge of the recorded image becomes uneven and is not clear). .

(hereinafter referred to as uneven edges) may result in a recorded image, or in the worst case, the ink layer may not be cut and not be transferred to the recording medium. The present inventor investigated the relationship between the breaking strength of the ink layer and the recorded image in double-density recording using various recording media with different breaking strengths of the ink layer, and found that the breaking strength of the ink layer was 2.
At 5℃, 30-80 kg/c rrr
It has been found that it is very effective to set it more preferably to 35 to 60 kg/crd.

In the present invention, the value of breaking strength is determined by testing a dumbbell-shaped ink film with a uniform thickness using a tensile strength tester (Tensilon RT).
M-100, manufactured by Toyo Baldwin Co., Ltd.) at a temperature of 2.
The yield value (kg/c rrf) obtained from the data is measured at 5° C. and a tensile speed of 200 mm/min.

A dumbbell-shaped (JISK7113.2 type test piece) ink film is produced as follows. That is, the same ink material as the ink layer used for the thermal transfer material is applied onto the release paper using an applicator, a wire bar, etc., so that the thickness after drying is about 35 μm. After the ink layer dries,
The release paper is removed to create an ink film.

Further, the ink layer of the thermal transfer material of the present invention has a melt viscosity of 3X 10' to 5X 10'cPoi at 120°C.
se.

More preferably, the poise is 7×10'-4×10'cPoise.

A) If the melt viscosity of the ink layer is too small, a large amount of the ink layer will be transferred with one heat application in the case of double-density recording.
Since only a small amount of the ink layer is transferred in the subsequent heat application, the density of the recorded image decreases or density unevenness occurs. On the other hand, if the melt viscosity of the ink layer is too high, the ink layer and the recording medium will stick to each other and become difficult to separate, which is not preferable.

In the present invention, the melt viscosity is a value measured using a B-type viscometer (Rotovisco TK-I-0.3, manufactured by Ichika Co., Ltd.).

In the thermal transfer material of the present invention, the ink layer is a mixture of a binder and a coloring material. As the material used for the binder, ethylene-vinyl acetate copolymer or ethylene-ethyl acrylate copolymer is preferable as it has film properties and softens/melts well upon application of heat. Among them, Kosenshin-vinyl acetate copolymer is preferred. The copolymerization ratio of ethylene and vinyl acetate is 90:10
~50: 50 is good, softening point (ring and ball method) is 70-1
An ethylene-vinyl acetate copolymer having a temperature of 30°C, more preferably tL< of 85 to 100°C is preferable. The copolymerization ratio of ethylene and ethyl acrylate of the ethyl 1 non-ethyl acrylate L--) copolymer is preferably 90:10 to 65:35, and the softening point (ring and ball method) is 70 to 130°C, preferably 85 to 100. Preferably, the temperature is within the range of °C.

If most of the binder is composed of ethylene-vinyl acetate copolymer or ethylene-ethyl acrylate copolymer, the melt viscosity will be increased and the breaking strength of the ink layer will also be increased. Therefore, in order to adjust the melt viscosity of one ink layer and the breaking strength of the ink layer, we use natural waxes such as carnauba wax, Montan wax 9-linole wax, paraffin wax, microcrystalline wax, castor wax, polyethylene wax, Sasol wax, etc. Synthetic wax, its low acid wax.

The wax may be selected from waxes such as ester wax, polyethylene wax, polypropylene wax, etc. One or more waxes may be mixed into the binder.

The content of ethylene-vinyl acetate copolymer or ethylene-ethyl acrylate copolymer in the binder is
40 to 80% by weight, more preferably 45 to 7% by weight based on the binder
0% by weight is preferred. In addition, the wax content is 20
-60% by weight, more preferably 25 to 50% by weight.

Further, the binder may contain a tackifier so that the ink layer firmly adheres to the recording medium. Tatsukifa (Years include coumaron indene resin, phenol/formaldehyde resin, polyterpene resin, xylene/formaldehyde resin, polybutene, rosin pentaerythritol ester, rosin glycerin ester,
1 selected from hydrogenated rosin, hydrogenated rosin methyl ester, hydrogenated rosin triethylene glycol ester, hydrogenated rosin pentaerythritol ester, polymerized rosin ester, aliphatic petroleum resin, alicyclic petroleum resin, synthetic polyterpene, pentagene resin, etc. species or two
Use by mixing more than one species.

When the binder contains tackifier, the content of tackifier is preferably 5 to 15% by weight, more preferably 7 to 12% by weight, based on the binder.

In the thermal transfer material of the present invention, one of the preferred embodiments of the binder is, for example, ethylene-vinyl acetate copolymer with 40%
It contains 25-50% by weight of ~70 weight 11 wax and 7-12% by weight of tackifier, and the colorant is dispersed in this binder to increase the breaking strength of the ink layer to 30-80 kg/kg at 25°C. Err? Adjust to the range of

Examples of colorants include carbon black, nigrosine dye, lamp black, Sudan Black SM, Fast Yellow 61 Benzine Yellow Pigment Yellow,
Indofast Orange, Irgazine Red, Varanitroaniline Red, Toluidine Red, Carmine F
B, Permanent Bordeaux FRR, Pigment I
Nonji R1 Resole Red 2G, Rake Red C1
0-Damine FB, Rhodamine B Lake, Methyl Violet B Shijiki, Phthalocyaning Blue, Pigment Blue Brilliant Green B1 Green for Phthalocyanine, Oil Yellow GG, Zapon Fast Yellow C
GG.

Kayaset Y963, Sumi Blast Yellow G, Zapon Fast Orange RR, Oil Scarlet, Sumi Blast Orange G1 Orazur Brown G, Zabon Fast Scarlet CG, Eisen Subiron L, = Tsudo F
4R, Fastgen Blue 5007, Sudan Blue,
Conventionally known coloring agents such as Oil Peacock Blue are used in combination or two or more of them are used in combination.

The amount of coloring material contained in the ink layer is preferably 1 to 50% by weight, more preferably 5 to 35% by weight, based on the entire ink layer. If the amount of coloring material is less than 1% by weight, the density of the recorded image will be extremely low (and if it exceeds 50% by weight, the recording energy will increase, the breaking strength of the ink layer will decrease, or the image will not be transferred to the recording medium). This is undesirable because it causes problems such as decreased sexual performance.

Conventionally known plastic films and paper can be used as the base material, but in double-density recording, heat is applied many times to the same location on the base material, so for example, aromatic polyamide film, polyphenylene sulfide film, polyamide Preferably, materials with high heat resistance such as ethereal ketone or condenser paper are used. In addition, when using polyester film (especially polyethylene terephthalate film, abbreviated as PET film), which has been suitably used in conventional thermal transfer materials, a heat-resistant and slippery material is applied to the surface opposite to the ink surface as a back treatment. It is preferable to provide one. The thickness of the base material is preferably 3 to 20 μm, more preferably 4 to 12 μm. As long as the material has high strength and heat resistance, it is also possible to use a material as thin as 3 μm or less. Further, excessively thick materials are not preferable because they have poor thermal conductivity.

The thickness of the ink layer is 15 to 30g1rd in terms of dry coating weight.
is preferable, and more preferably 16 to 25 g/nf.

If the ink layer thickness is less than 15 g/rrf, sufficient recording density cannot be obtained in double-density recording, and if it exceeds 30 g/rrf, problems such as curling of the thermal transfer material and increase in recording energy occur, which is not preferable.

In producing the thermal transfer material of the present invention, a binder material selected from the above-mentioned viewpoints is dissolved in an organic solvent such as toluene, methyl ethyl ketone, isopropyl alcohol, methanol, xylene, etc., and a coloring material is mixed therein, and then the binder material is mixed with a coloring material and then processed using a sand mill or the like. It can be sufficiently dispersed using a dispersing machine, and then applied onto a substrate using a coating method such as a bar code or gravure coating. Alternatively, the resin may be heated to a temperature above its softening point to disperse the coloring material, and then applied using a so-called hot melt coating. Furthermore, the resin or colorant may be applied as an aqueous emulsion by adding a dispersant such as a surfactant.

When applying ink to the substrate, apply a single color (e.g. black) to the entire surface.
If colored ink is applied, a single color thermal transfer can be obtained. In addition, multiple color ink layers (for example, cyan ink, magenta ink, yellow ink, blue ink, green ink Alternatively, a thermal transfer material capable of multi-color recording can be obtained by repeatedly applying different colors (such as red ink) and recording so that the colors are overlapped during printing.

EXAMPLES The present invention will be explained in more detail with reference to Examples below.

Tue” January 1- After mixing the above materials in a ball mill, the thickness is 6 μm.
A heat-sensitive transfer material of the present invention was obtained by coating onto a PET film with a width of 260 mrn and a #6° Meyer bar at a dry coating weight of 20 g/r+.

In addition, a back treatment agent of silicone-acrylic-urethane ternary copolymer was applied in advance to the opposite side of the polyester 71' lume from the ink-coated side so that the dry coating weight was 11O, 3g/rrr. I used what I had. The film strength of the ink layer was measured and the results are shown in Table 1.

On the other hand, a facsimile manufactured by Canon Co., Ltd. (trade name: Canofax 630) was partially modified and used as an evaluation machine for double-density recording facsimile equipment.

The mechanical and physical conditions of this device are as follows.

(1) Equipped with a full multi-thermal head of 8pel/rnm, 1kg1c per platen roller
It is fixed with a pressure of rd.

(2) The feeding amount of the thermal transfer material is about 115 times the feeding amount of the recording medium.

(3) The thermal transfer material and the recording medium are fed in opposite directions.

(4) The printing speed on the recording medium is 25 mm/sec. Further, the relative speed between the recording medium and the thermal transfer material at this time was 31.2 mm/sec.

(5) The surface heat energy of the thermal head is 22m
J/mrr? It is.

Next, the above-mentioned thermal transfer material was inserted into this apparatus, a recorded image was formed on recording paper, and evaluated.

The evaluation results are shown in Table 1.

Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 [8.7 parts by weight of glycerin ester of rosin Example 8 Example 9 Example 10 Example 11 Implementation Example 12 Example 13 Comparative Example 2 Comparative Example 3 The materials of Examples 2 to 13 were mixed to produce 12 types of thermal transfer materials in the same manner as in Example 1. Measure the film strength of the ink layer of each heat-sensitive transfer material and use the results as the first
Shown in the table.

Using the thermal transfer materials of Examples 2 to 13 above, recorded images were formed on recording paper in the same manner as in Example 1, and evaluated. The evaluation results are shown in Table 1.

Comparative Example 1 1. 900 parts by weight of toluene Comparative Example 4 Comparative Example 5 Comparative Example 6 The materials of Comparative Examples 1 to 6 above in the table were mixed respectively to form Example 1.
Six types of thermal transfer materials were produced in the same manner as above.

The film strength of the ink layer of each thermal transfer material was measured, and the results are shown in Table 1.

Using the thermal transfer materials of Comparative Examples 1 to 6 above, recorded images were formed on recording paper in the same manner as in Example 1, and evaluated.

The evaluation results are shown in Table 1.

I--J Breaking strength is the average value of three measurements.

The evaluation of scumming, whisker-like edges, and uneven edges is as follows.

Background smudge [(Significantly smudged) Beard-like edges, uneven edges [Effects of the invention] As explained above, the thermal transfer material of the present invention has an ink layer with a breaking strength of 30 to 80 kg/crd at 25°C. Even when used for double-density recording, scumming, whisker-like edges, and uneven edges do not occur, and a clear and high-quality recorded image can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an example of an apparatus using the thermal transfer material of the present invention, and FIGS. 2 to 5 are partial side views showing an example of using the thermal transfer material of the present invention for double-density recording. FIG. 6 is a plan view showing an example of an image recorded by a conventional thermal transfer material. l...Thermal transfer material 2...Recorded object 3...Recording head 3a...Heating element H--2? figure

Claims (5)

[Claims] (1) In a thermal transfer material having an ink layer on a base material,
The breaking strength of the ink layer is 30 to 80 kg at 25°C.
/cm^2. (2) In a thermal transfer material having an ink layer on a base material,
The ink layer has a binder and a colorant, and the binder contains 40 to 80% of an ethylene-vinyl acetate copolymer.
A thermal transfer material characterized by containing 20 to 60% by weight of wax. (3) Add 5 to 1 tatsuki fire in the binder.
The thermal transfer material according to claim (2), containing 5% by weight. (4) In a thermal transfer material having an ink layer on a base material,
The ink layer has a binder and a colorant, and the binder contains 45 to 70% of an ethylene-vinyl acetate copolymer.
1. A heat-sensitive transfer material characterized by containing 25 to 50% by weight of wax and 7 to 12% by weight of tackifier. (5) On the base material, the breaking strength at 25°C is 30 to 80 kg/
Using a thermal transfer material having an ink layer in the range of cm^2, the distance that the thermal transfer material moves relative to the recording head is longer than the distance that the recording medium moves relative to the recording head within the same time. A thermal transfer recording method characterized by a shorter length.