JPH03178457A - Thermal transfer recording - Google Patents

Abstract

PURPOSE:To allow sticking not to occur even by double density recording by a method wherein transfer recording is performed, a contact part of a thermal transfer material with a material to be recorded is heated separately from a recording signal to be applied to a recording head. CONSTITUTION:Basically a thermal transfer material 1 is piled on a material 2 to be recorded of paper or the like, and the material 2 to be recorded is moved at a different speed from that of the thermal transfer material 1. They are heated with a recording head 3 such as a thermal head or the like. Thereby, heating fusible ink of the thermal transfer material 1 is transferred successively to the material 2 to be recorded, and a recorded image is obtained. That is, there is a relative speed between the thermal transfer material 1 and the material 2 to be recorded. The head 3 does not move, and the thermal transfer material 1 moves slower than the material 2 to be recorded. That is, when a distance where the thermal transfer material 1 moves is compared with a distance where the material 2 to be recorded moves in same time, the moved distance of the thermal transfer material 1 is shorter.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a thermal transfer recording method that allows good recording to be obtained even when the amount of thermal transfer material used is reduced.

[Conventional technology]

The thermal transfer recording method has the general features of the thermal recording method, such as the equipment used is lightweight, compact, noiseless, and has excellent operability and maintainability. It has the feature of excellent durability and has been widely used recently.

This heat-sensitive transfer recording method uses a heat-sensitive transfer material in which a heat-transferable ink layer consisting of a colorant dispersed in a heat-melting binder is coated on a base material, which is generally in the form of a sheet. By superimposing 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 transfer recording image is formed on the edge to be recorded according to the 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 (hereinafter referred to as a one-time method), so it is disposable and the running cost is high. There was also concern that confidential information could be leaked from used thermal transfer materials.

On the other hand, U.S. 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,
This recording method has conventionally had the following problems.

In other words, in double-density recording, heat is applied multiple times to the same part of the ink layer, and recording is performed while the thermal transfer material and the recording medium slide, so the breaking strength of the ink layer is lower than that of the one-time method. This requires a material that is much stronger than the layer, and there is a problem in that it is easy to cause so-called "sticking" in which the heat-sensitive transfer material and the recording medium do not peel off immediately after recording.

The present invention has been made in view of the actual situation described in item L, and an object of the present invention is to provide a thermal transfer recording method that does not cause "sticking" even during double-density recording.

[Means for Solving the Problems] The present invention provides a heat-sensitive transfer material in a heat-sensitive transfer recording method that uses a heat-sensitive transfer material having an ink layer on a base material and transfers a desired image onto a recording medium by a recording head. A double-density recording method in which the conveyance relative speed to the recording head is slower than the relative speed of the recording medium, and during transfer recording, the contact area between the thermal transfer material and the recording medium is separated from the recording signal applied to the recording head. According to the present invention, it is possible to suppress the occurrence of so-called "sticking" and obtain a high-quality recorded image.

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

In addition, in the following description, "%" and 1
Parts are by weight unless otherwise specified.

The thermal transfer recording method (double-density recording method) using a thermal transfer material according to the present invention basically consists of a thermal transfer material 1 and a cover such as paper, as shown in an example of implementation in FIG. By overlapping the recording medium 2 and moving the recording medium 2 at different speeds with respect to the thermal transfer material 1, and heating the recording medium such as a thermal head with the rad 3, the thermofusible ink of the thermal transfer material 1 is sequentially applied. A recorded image is obtained by transferring it to a recording medium 2.

The thermal transfer material 1 and the recording medium 2 are continuously moved in the directions of arrows A and B (B is faster than A) by the rotation of the capstan roller 12, pinch roller 13, and platen roller 11, respectively. Recording is performed on the recording medium 2 one after another. The capstan roller 12 and the pinch roller 13 are driven by a motor 14, and the platen roller 11 is driven by a motor 15, respectively. The transported thermal transfer material 1 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. 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,
Comparing the distance traveled by the thermal transfer material 1 and the distance traveled by the recording medium within the same time, the distance traveled by the thermal transfer material 1 is shorter. As a result, with this recording method,
Recording is performed as shown in the figure.

As shown in FIG. 2, if the width of the heating element 3a of the recording pad 3 in the direction of feeding the thermal transfer material (in the direction of the arrow) is 1
The second heat application is applied to completely unused heat-sensitive transfer material 1 in a uniform size (FIG. 2).

The heat-sensitive transfer material 1 includes a heat-melting ink layer 1b provided on a support la.

However, when heat is applied for the second time, the recording medium 2 is moving in the direction of arrow B, while the thermal transfer material l is fl/N with respect to the recording head 3 (the value of N is the thermal transfer material 1 In this case, N is the number obtained by dividing the moving distance of the recording medium 2 by the moving distance of the thermal transfer material 1 within a certain time. , the (f-(j2/N)) portion of the thermal transfer material 1, which has already been subjected to heat once, will be used again (FIG. 3).

When heat is applied continuously in the lateral direction in this way, the heat-sensitive transfer material subjected to the second and subsequent heat applications has a fl/N
Only one part is in an unused state, and the rest have already been heated several times by angle/N (Fig. 4). 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 moves by jQlN with respect to the recording head 3 during the second, third, etc. heat application, but the thermal transfer material 1 moves less than L and more than fl/N. If so, the thermal transfer material 1 can be saved. The most efficient movement amount of the thermal transfer material 1 is the case where it moves by fl/N between the application of heat and the next application of heat. The above N is preferably 2 to 10, more preferably 3 to 8.

In the above explanation, an example was shown in which the recording head 3 does not move. However, even when the thermal head 3 moves, the moving distance of each of the thermal transfer material 1 and the recording medium 2 is determined by the recording head 3.
If the distance from the recording head 3 is taken as a reference, it can be considered in the same way as the example explained in FIGS. 1 to 4. In other words, in the thermal transfer recording method of the present invention, the distance that the recording medium 2 moves relative to the recording head 3 within the same time is
It is sufficient that the distance that the thermal transfer material 1 moves relative to the recording head 3 is shorter.

Now, as is clear from the above explanation, since the thermal transfer material 1 is used while sliding on a recording medium such as a piece of paper, if the breaking strength of the ink layer 1b is too small, it may cause damage to the surface of the recording medium. Scratching causes scumming and whisker-like edges, which is undesirable. Furthermore, if the breaking strength of the ink layer 1b is too large, it becomes difficult to break well at the boundary between the heat-applied part and the non-heat-applied part of the ink layer 1b, resulting in poor cutting (the edges of the recorded image become uneven). The ink layer may not be clear (hereinafter referred to as the uneven edges), or the thermal transfer material and the recording medium may become stuck, and 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 thermal transfer materials with different breaking strengths of the ink layers, and found that the printing signal applied to the printing head is It has been found that it is very effective to perform recording while separately heating the contact area between the thermal transfer material and the recording medium. The reason for this is that by heating the contact portion, the breaking strength of the ink layer is apparently reduced, thereby preventing "sticking".

Furthermore, the above effect shows that the breaking strength of the ink layer at 25°C is 20 to 808g7cm2, especially 25 to 78g/
It was noticeable at cm'. That is, if the breaking strength of the ink layer is less than 20 g/cm2 at 25°C, a large amount of ink layer will be transferred with one heat application, and only a small amount of ink layer will be transferred with the second and subsequent heat applications. Therefore, the density of the recorded image decreases or density unevenness occurs. On the other hand, if it is larger than 808g7cm2, it is not preferable because sticking occurs even when the contact area between the heat-sensitive transfer material and the recording medium is heated.

The features of the present invention are: - As mentioned above, the contact portion between the thermal transfer material and the recording medium is heated separately from the recording signal applied to the recording head; Refers to the part where the surface of the ink layer of the material and the surface of the recording medium are in substantial physical contact, especially the part located at the same position or temporally before the actual position where thermal transfer is performed by the recording head. In other words, it refers to a portion that has not yet been thermally transferred. In the present invention, as long as this part is heated, the surrounding area may be heated as well. That is, the breaking strength of the ink layer before being thermally transferred is apparently reduced by the heat treatment, and it is sufficient that the ink layer is heated so that it can be smoothly transferred onto the recording medium during thermal transfer. Even if the contact portion is heated, it will not be effective if the contact portion is not affected during transfer.

Further, it is sufficient that the contact portions are in substantial contact with each other, and it is not strictly necessary that the entire surface is physically in complete contact with each other; even if there is a slight gap, a sufficient heating effect can be obtained. In other words, in the present invention, contact means contact to the extent that a heating effect can be substantially obtained.

In the present invention, preferable heating means include heating the entire recording head separately from the recording signal applied to the recording head, or heating a platen roller facing the recording head and sandwiching the thermal transfer material and the recording medium. can be used for effective heating.

The heating temperature varies depending on the type of ink, the ink layer, the base material, the material and thickness of the recording medium, the conveyance speed, etc., but when heating the entire recording head, the temperature of the part of the recording head that comes into contact with the thermal transfer material Approximately 30°C to 60°C, preferably 30°C
It may be heated to ~50°C. When heating the platen roller, it is effective to keep the temperature of the portion of the platen roller in contact with the recording medium at approximately 30°C to 80°C, preferably 30°C to 70°C. When the breaking strength of the ink layer used is high, it is preferable to carry out the process at a relatively high temperature, and when the breaking strength of the ink layer used is low, it is preferable to carry out the process at a relatively low temperature. In any of the above cases, sticking will not be reduced below 30°C, and if the recording head is above 60°C or the platen roller is below 80°C.
In this case, the breaking strength of the ink layer will decrease more than necessary.
Overall fogging may occur on the recording medium, a large amount of the ink layer may be transferred, and the density may decrease from the second time onward, or density unevenness may occur.

That is, in the present invention, heating is performed so that the ink layer is transferred smoothly, and the temperature of the ink layer of the thermal transfer material is 3 to 40 degrees Celsius, more preferably 5 to 30 degrees Celsius lower than the melting point of the ink. The temperature and time should be such that the temperature is reached. The melting point of the ink was determined using a Shimadzu r flow tester CFT-500J at a heating rate of 2°C/min.
Extrusion pressure 10 Kg f/cm2, die diameter 0
．． 5 mm and the die length is 1.0 mm. If the breaking strength of the ink layer on the substrate is relatively high, the degree of heating may be made relatively strong, and vice versa, appropriate transfer characteristics can be obtained by making it weak.

To heat the recording head and platen roller, you can attach a ceramic heater to the recording head or platen roller, heat it with hot air using a heating blower, or, in the case of the platen roller, make it hollow and insert a halogen lamp heater. However, either case is fine.

In addition, in the present invention, the value of breaking strength is determined by using a tensile strength tester (Tensilon RTM-100, manufactured by Toyo Baldwin Co., Ltd.) using a dumbbell-shaped ink film of uniform thickness.
The yield value (Kg/cm'') obtained from the data is measured at a temperature of 25°C and a tensile strength of 200 mm for 7 minutes.

A dumbbell-shaped (JIS K 7113.2 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 form an ink film.

Other configurations related to the method of the present invention will be described below.

The ink layer of the heat-sensitive transfer material that can be used in the heat-sensitive transfer recording method of the present invention is a mixture of a binder and a coloring material. The material used for the binder has film properties,
Ethylene-vinyl acetate copolymer or ethylene-ethyl acrylate copolymer is preferred as it softens/melts well upon application of heat. Among these, ethylene-vinyl acetate copolymer is preferred. The copolymerization ratio of ethylene and vinyl acetate is preferably 90:10 to 50:50, and the softening point (ring and ball method) is 70 to 130°C, more preferably 85°C.
Ethylene-vinyl acetate copolymers in the range of ~100°C are preferred. The copolymerization ratio of ethylene and ethyl acrylate in the ethylene-ethyl acrylate copolymer is 90:10 ~
65:35 is good, softening point (ring and ball method) is 70-130℃
, more preferably in the range of 85 to 100°C.

When most of the binder is composed of ethylene-vinyl acetate copolymer or ethylene-ethyl acrylate copolymer, the breaking strength of the ink layer is also increased. Therefore, in order to adjust the breaking strength of the ink layer, carnauba wax,
Montan wax.

Natural waxes such as linole wax, synthetic waxes such as paraffin wax, microcrystalline wax, castor wax, polyethylene wax, Sasol wax, and other acid waxes.

One or two types of waxes selected from ester wax, polyethylene wax, polypropylene wax, etc.
It is preferable to mix a mixture of waxes with the binder.

Further, the binder may contain a tackifier so that the ink layer firmly adheres to the recording medium. Tackifiers include coumaron, endene resin, phenol/formaldehyde resin, polyterpene resin, xylene/formaldehyde resin, polybutene, rosin pentaerythritol ester, rosin glycerin ester, hydrogenated rosin, hydrogenated rosin methyl ester, hydrogenated rosin triethylene glycol. One or a mixture of two or more selected from esters, hydrogenated rosin pentaerythritol esters, hybrid rosin esters, aliphatic petroleum resins, alicyclic petroleum resins, synthetic polyterpenes, pentagene resins, etc. may be used.

One of the preferable embodiments of the binder of the thermal transfer material that can be used in the thermal transfer recording method of the present invention is, for example, 40 to 70% by weight of ethylene-vinyl acetate copolymer, 25 to 50% by weight of wax, and tackifier. 7-12% by weight
A colorant is dispersed in this binder to increase the breaking strength of the ink layer from 20 to 80 K at 25°C.
It can be adjusted within the range of g/cto2.

Examples of colorants include carbon black, nigrosine dye, lamp black, Sudan black SM, Fast Yellow, benzine yellow, pigment yellow, Indofast orange, irgazine red, paranitroaniline red, toluidine red, and carmine. FB, Permanent Bordeaux FRR, Pigment Orange R, Linole Red 2G, Lake Red C,
Rhodamine FB, Rhodamine B Lake, Methyl Violet B Lake, Phthalocyanine Blue, Pigment Blue, Brilliant Green B, Phthalocyanine Green, Oil Yellow GG, Zapon Fast Yellow〇〇G
, Kayaset Y963, Sumiplast Yellow GG, Zapon Fast Orange RR, Oil Scarlet, Orazol Brown G, and the like may be used singly or in combination of two or more.

The amount of coloring material contained in the ink layer is desirably 35 parts by weight of the total ink layer. If the amount of coloring material is less than 3% 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,
Alternatively, the problem of deterioration of transferability to the recording medium may occur, which is undesirable.

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 ether ether ketone and 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, it is necessary to provide a heat-resistant and slippery material on the surface opposite to the ink surface as a backside treatment. is preferable. The thickness of the base material is preferably 3 to 20 μm, and more preferably 4 to 12 μm.
l1ns 11 Tha 1 animal\謔, HA謔, can be used. Further, excessively thick materials are not preferable because they have poor thermal conductivity.

The thickness of the ink layer is 7 to 20 g/I in terms of dry coating weight! 1
2 is preferable, and 8 to 18 g/m2 is more desirable.

If the ink layer thickness is less than 7 g/n+2, sufficient recording density cannot be obtained in double-density recording, and if it exceeds 20 g/m2, problems such as curling of the thermal transfer material and increased recording energy will occur, so it is preferable. do not have.

In manufacturing a thermal transfer material, a binder material selected from the above-mentioned viewpoints is dissolved in an organic solvent such as toluene, methyl ethyl ketone, isopropyl alcohol, methanol, or xylene, and a coloring material is mixed with the binder material using a dispersion machine such as a sand mill. It can be sufficiently dispersed and applied onto the base material using a coating method such as barcode coating or gravure coating. In addition, after heating the resin above its softening point and dispersing the coloring material,
It may be applied using a so-called hot melt coat.

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.

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

That is, according to Examples 1 to 3 and Comparative Examples, thermal transfer material (I)
- (TV) was created and the transfer test described below was conducted.

Example 1 After mixing and preparing the above materials in a ball mill, a thickness of 6 μm was prepared.
The mixture was coated onto a PET film having a width of 260 mm using a #60 Meyer bar so that the dry coating weight was 14 g10+2 to obtain a thermal transfer material CI).

In addition, on the opposite side of the polyester film from the ink-coated side, a back treatment agent of silicone-acrylic-urethane ternary copolymer was applied in advance so that the dry coating weight was 0.3 g/ln2. I used something. When the film strength of the ink layer was measured, the breaking strength was 20 kg at 25°C.
/c[112.

Example 2 45 parts by weight of the ester wax of Example 1, ethylene-
A heat-sensitive transfer material (II) was obtained by carrying out the same treatment as in Example 1 except that the vinyl acetate polymer was used in an amount of 40 parts by weight. The breaking strength of this ink layer was 50 kg/cm2.

Example 3 25 parts by weight of the ester wax of Example 1, ethylene-
A heat-sensitive transfer material (III) was obtained by carrying out the same treatment as in Example 1 except that the vinyl acetate polymer was changed to 60 parts by weight. The breaking strength of this ink layer was 80 kg/cm''.

Comparative Example 1 A heat-sensitive transfer material (rV) was obtained by carrying out the same treatment as in Example 1 except that the ester wax of Example 1 was changed to 5 parts by weight and the ethylene-vinyl acetate polymer was changed to 80 parts by weight. The breaking strength of this ink layer was 100 Kg/cm2.

Canon facsimile, product name Canofax 6
30 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) A fully multi-recording head of 8 Pel/mm is installed, and a ceramic heater (manufactured by Itame Dennetsu Co., Ltd.) is attached to the aluminum holder of the recording head.
It is now possible to heat the entire recording head independently.

(2) The platen roller is a 20 mm diameter hollow iron vibrator covered with silicone rubber with a rubber hardness of 40', and a halogen heater (SOOW, manufactured by Matsushita Electric Industrial Co., Ltd.) is installed in the hollow of the iron pipe, and the platen roller can be operated independently. It is possible to heat it.

(3> The feeding amount of the thermal transfer material is approximately 1/6 of the feeding amount of the recording medium.

(4> The feeding directions of the thermal transfer material and the recording medium are opposite to each other.

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

(6) The surface heat energy of the thermal head is 22mJ
/ll11m2.

Next, insert the aforementioned thermal transfer material into this device and transfer it to the recording paper.
Forms a recorded image of "Image Electrophotography Society A2 chart" and "
``stickiness'' was evaluated. The evaluation results are shown in Table 1.

Table × With sticking Note 1) Heating temperature is the surface temperature on the heating element of the recording head,
and the surface temperature of the platen roller.

(Effects of the Invention) As explained above, the thermal transfer recording method of the present invention records while heating the contact area between the thermal transfer material and the recording medium separately from the recording signal applied to the recording head. A clear and high-quality recorded image can be obtained without causing "sticking" between the recording medium and the recording medium.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view showing an example of an apparatus used to carry out the thermal transfer recording method of the present invention, and FIGS. 2 to 4 illustrate the double-tight recording It fl related to the thermal transfer recording method of the present invention. FIG. 4 is a partial side view of the transfer process, in which the transfer is performed in the order of FIG. 2→FIG. 4. l...Thermal transfer material 1a...Base material 1b.
... Ink layer 2 ... Recorded object 3 ...
...Recording head 3a-heating element 10...
Take-up roller 11...Platen roller 12...Capstan roller 14.15...
・Motor 16------Spring

Claims (1)

[Claims] 1. Transport of the thermal transfer material to the recording head in a thermal transfer recording method in which a thermal transfer material having an ink layer on a base material is used to transfer a desired image onto a recording medium by a recording head. This is a double-density recording method in which the relative speed is lower than the speed of the recording medium, and during transfer recording, the contact area between the thermal transfer material and the recording medium is heated separately from the recording signal applied to the recording head. Features a thermal transfer recording method. 2. The thermal transfer recording method according to claim 1, wherein the entire recording head is heated in a range of 30°C to 60°C. 3. The platen roller that conveys the recording medium is heated to 30°C.
2. The thermal transfer recording method according to claim 1, wherein heating is performed in a range of 80 DEG C. to 80 DEG C. 4. The thermal transfer recording method according to claim 1, wherein the ink layer on the substrate has a breaking strength of 20 to 80 kg/cm^2 at 25°C.