JPH06127149A - Thermal transfer recording medium - Google Patents

Abstract

PURPOSE:To provide a thermal transfer recording medium suitable for high speed printing, satisfying both of printing quality and image density, not contaminating the surface of a receiving recording medium, capable of obtaining stable transfer properties and printing runnability even at high temp. and capable of obtaining a lusterless transfer image excellent in reading properties in the case of two or more-time use or n-time speed type printing. CONSTITUTION:A thermal transfer recording medium is constituted of a sheet like base material and the heat-melt ink layer provided on the base material. The heat-melt ink layer contains a low m.p. crystalline material, a resin material and a coloring material. The low m.p. crystalline material and the resin material are in a compatible state and at least a part of the low m.p. crystalline material forms a compd. along with the resin material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive transfer recording medium for recording by transferring a heat-meltable ink material onto a medium to be transferred using a heat-sensitive head.

[0002]

2. Description of the Related Art Transfer recording onto a transfer medium using a heat-sensitive transfer recording medium is performed by bringing the heat-sensitive transfer recording medium and the transfer-receiving medium into close contact with each other on a heat-sensitive head under a constant pressure and applying from the heat-sensitive head. This is performed by melting the heat-meltable ink layer (color material layer) of the heat-sensitive transfer recording medium with heat energy and transferring the melted ink layer onto the medium to be transferred. At the time of this transfer, most of the heat-meltable ink layer on the thermal transfer recording medium is transferred onto the transfer target medium. Therefore, in order to perform recording using the thermal transfer recording medium, the same area as the recording area is required. The above thermal transfer recording medium is required. For this reason, the recording method using the thermal transfer recording medium has a higher recording cost than the electrophotographic method or the inkjet method.

In order to solve this high recording cost, a thermal transfer recording medium (multi-time type thermal transfer recording medium) which can be used a plurality of times has been developed. As a heat-sensitive transfer recording medium intended to be used a plurality of times, for example, in JP-A-54-68253, a heat-sensitive transfer recording medium in which a resin is used to form a fine porous layer and the pores thereof are impregnated with a heat-sensitive ink. Is proposed. In this heat-sensitive transfer recording medium, since the heat-sensitive ink is transferred from the pores of the holes to the medium to be transferred by the penetration phenomenon, it takes time for the heat-sensitive ink to be melted by heat and penetrate into the pores, and the printing speed is slow. There is a drawback that. Further, since the permeation amount of the thermal ink is limited, it has a big drawback that it is difficult to obtain a high-density transferred image. Also, a similar proposal is disclosed in
Although described in Japanese Patent Laid-Open No. 5-105579, it has the same drawbacks as described above.

Further, in Japanese Patent Laid-Open No. 56-89984, an organic pigment such as carbon black, a metal such as aluminum or aluminum oxide, a fine powder of a metal oxide, or the like is contained in a solid ink layer of a recording medium. There is described a thermal transfer recording medium which can be used a plurality of times by adding the inorganic pigment as a filler. In this thermal transfer recording medium, the compounded filler forms a porous layer, and the voids of the porous layer are impregnated with a solid ink in which a coloring material such as a dye or a pigment is dissolved or dispersed in a low melting point resin. The structure is a solid ink layer. Then, when heat is applied to this recording medium, the solid ink is melted and exudes from the porous layer, and is transferred onto the transfer medium. Such a recording medium is also unsuitable for high-speed transfer for the same reason as the fine porous layer made of resin, and it is difficult to obtain a high-density transferred image. Further, when a coloring material such as carbon black is used as the filler, some of these fillers are easily transferred, and in the case of color recording, color turbidity is likely to occur.

On the other hand, as a method of eliminating the high recording cost, instead of using the same thermal transfer recording medium a plurality of times, the thermal transfer recording medium and the transferred medium have the same feed speed (1
There is also an attempt to reduce the recording cost by reducing the feeding speed of the heat-sensitive transfer recording medium and the medium to be transferred to be smaller than that of the heat-sensitive transfer recording medium (n times speed), instead of (1). For example, JP-A-60-178088 discloses a heat-sensitive transfer recording medium in which an overcoat layer containing a resin and a wax as a main component is provided on a heat-meltable ink layer. By providing such an overcoat layer, it is possible to prevent rubbing stains caused by a difference in pressing pressure and relative speed between the heat-sensitive transfer recording medium and the transferred medium. However, an excessive melting phenomenon of the thermal transfer recording medium due to heat accumulation of the thermal head caused by a slow relative speed of the thermal transfer recording medium peculiar to the n-fold speed printing to the thermal head and the accompanying melting of the ink layer after printing occur It has not been possible to solve practical problems such as tailing stains and beard-like stains extending in a beard shape due to the spinnability of the melted ink material.

Further, Japanese Patent Laid-Open No. 2-204092 uses a thermal transfer ink in which a coloring material is dispersed in a hot-melt binder composed of an ethylene-vinyl acetate copolymer and a wax, and is used at room temperature (25 ° C.). A thermal transfer material and a thermal transfer recording method for preventing beard stains by defining the breaking strength of the above are described. However, there is little physical relationship between rupture strength, which indicates the mechanical strength of the material at room temperature, and beard stains caused by the spinnability of the material in the molten state. Cannot be As described above, at present, an n-fold speed thermal transfer recording medium which has a high image density, is suitable for high-speed printing, and solves the above problems has not yet been provided.

Further, in the conventional thermal transfer recording medium as described above, in order to improve the reproducibility of the obtained transfer image,
A film or the like having high surface smoothness and excellent dimensional stability is used as a base material, and the surface of the heat-meltable ink layer provided thereon also has high surface smoothness.
A transfer image obtained using such a thermal transfer recording medium has a surface that is extremely smooth and glossy. Therefore, when the transfer image needs to be read for a long time, the light from the light source is reflected, It has a drawback that the eyes are remarkably tired and the transferred image becomes difficult to see depending on the condition of the light source. To solve such a problem, for example, a heat-sensitive transfer recording medium in which a delusterant is added to a heat-meltable ink layer (Japanese Patent Laid-Open No. S60-18753)
56-164891) is proposed. However, in such a heat-sensitive transfer recording medium, the thickness of the heat-meltable ink layer for obtaining a transferred image having the same image density must be increased as compared with a normal heat-sensitive transfer recording medium to which a matting agent is not added. However, the thermal responsiveness of the heat-meltable ink layer is lowered, and the number of times of repeated use is reduced in a thermal transfer recording medium used a plurality of times.

[0008]

With the recent widespread use and development of information devices, printers, which are information output devices, are becoming faster, smaller, and more precise. However,
Conventional thermal transfer recording media that can be used a plurality of times have poor thermal responsiveness as described above, so that it is difficult to adapt to high-speed printing, and only printing quality and image density are poor.

Further, as a problem peculiar to the thermal transfer recording medium used a plurality of times, the surface of the thermal transfer recording medium used a plurality of times deteriorates, and the deteriorated surface causes the entire surface of the transferred medium pressed against for transfer. There is a problem of getting dirty. This stain tends to be more likely to become stain when the thermal response of the thermal transfer recording medium is increased for speeding up. Furthermore, the downsizing of the equipment causes the temperature inside the equipment to become higher than that of the conventional equipment during use, and the problem of this contamination becomes more and more serious. Further, when the temperature of the device becomes high as described above, as a peculiar problem, a reverse transfer phenomenon (when the heat-meltable ink layer of the heat-sensitive transfer recording medium is melt-transferred onto the transfer medium,
The phenomenon of defective printing that returns to the thermal transfer recording medium without being transferred, and the sticking phenomenon (the heat-meltable ink layer serves as an adhesive layer and the thermal transfer recording medium adheres to the transferred medium, and A phenomenon of poor runnability, which is a conveyance failure of the thermal transfer recording medium, occurs.

On the other hand, the n-fold speed thermal transfer recording medium has problems such as rubbing stains and beard stains in a more severe high temperature condition.

In addition to these, conventional multi-time and n
The double-speed type thermal transfer recording medium has a problem that the read image is inferior because the obtained transfer image has gloss. The present invention has been made in order to address such a problem, and is particularly adapted to high-speed printing when used multiple times (multi-time) or when performing n-fold speed printing,
Both print quality and image density are satisfied, the surface of the medium to be transferred is not polluted, stable transferability and print runnability are obtained even at high temperatures, and a transfer image with no gloss and excellent legibility is obtained. It is intended to provide a thermal transfer recording medium.

[0012]

The heat-sensitive transfer recording medium of the present invention is provided with a sheet-shaped base material, and is provided on the base material, selectively heated and melted, and transferred onto the transfer-target medium. In a thermal transfer recording medium having a heat-meltable ink layer, the heat-meltable ink layer contains at least a low melting point crystalline material, a resin material and a coloring material, and the low melting point crystalline material and the resin. While the materials are compatible with each other,
At least part of the low melting point crystalline material forms a compound with the resin material.

In the heat-sensitive transfer recording medium of the present invention, among the materials for forming the heat-meltable ink layer, the low-melting-point crystalline material and the resin material are compatible with each other, and at least a part of the low-melting-point crystalline material. Form a compound with the resin material. In this way, the low melting point crystalline material and the resin material are made compatible with each other,
In addition, by forming these compounds, good multi-time printability and n-fold speed printability can be obtained.

That is, when the low-melting-point crystalline material is incompatible with the resin material and is dispersed in the heat-meltable ink layer in an isolated state, the low-melting-point crystalline material having a small molecular weight forms a coating film. When it is dried by heating, it deposits on the surface thereof, and the printability of the obtained thermal transfer recording medium a plurality of times and the n-fold speed printability cannot be sufficiently exhibited. On the other hand, in the thermal transfer recording medium of the present invention, the low-melting-point crystalline material is made compatible with the resin material, and at least a part of the compound is used as a compound. The isolated portion is extremely small, shows stable transferability and printing runnability even at high temperatures, and does not stain the surface of the transfer medium.

The compound of the low melting point crystalline material and the resin material described above is preferably dispersed in the hot melt ink layer in the form of fine particles, and the average particle size of the fine particle compound is the hot melt ink. The thickness is preferably equal to or less than the layer thickness. If the particle size of the compound particles is so large as to exceed the thickness of the heat-meltable ink layer, the compound directly contacts the transfer medium before being transferred, which causes rubbing stains on the surface of the transfer medium. Further, the coarse compound particles mean that the crystal growth has progressed in the particles, and therefore, with respect to the heat energy instantaneously supplied, it is possible to favorably shift to the liquid phase state in which the crystal structure disappears. As a result, the melting of the heat-fusible ink layer becomes insufficient, and it becomes impossible to cope with high-speed printing by printing multiple times or n-fold speed type printing.

Further, when the low melting point crystalline material and the resin material are completely compatible with each other or when these compounds have a continuous solid phase structure, the low melting point crystalline material and the colorant are Cannot be sufficiently mixed, and as a result, the colorant is secondarily aggregated and settled, and poor dispersion of the heat-meltable ink coating liquid is likely to occur. When printing is performed using such a thermal transfer recording medium, only extremely low image density can be obtained.

The dispersion state of the compound formed by the low-melting-point crystalline material being compatible with the resin material varies depending on the combination of materials and the coating film forming conditions. Therefore, the optimum dispersion state is set for each material used. It shall be.

The low melting point crystalline material used in the thermal transfer recording medium is extremely easy to crystallize, but when dispersed in a state compatible with the resin material, crystal growth is suppressed by the resin material. It is not possible to have a smooth surface and a fracture surface without unevenness, which is usually observed when crystallized, and as a result, it is easy to form an uneven surface state. In the heat-sensitive transfer recording medium of the present invention, since the low melting point crystalline material and the resin material are compatible with each other, the surface and the fracture surface of the resulting heat-meltable ink layer are uneven. Therefore, the surface of the obtained transferred image is also uneven, so that the light from the light source is scattered, and it becomes easy to read without gloss. The surface and fracture surface irregularities of the heat-meltable ink layer are, for example, surface roughness Ra (center line average roughness).
It is preferably about 0.3 to 0.4 μm.

Among the materials constituting the heat-meltable ink layer of the heat-sensitive transfer recording medium of the present invention, examples of the low melting point crystalline material and the resin material include ethylene low melting point crystalline material and ethylene resin material. You can In order to satisfactorily make such an ethylene-based low melting point crystalline material and an ethylene-based resin material compatible with each other to form these compounds, it is preferable that both have extremely high affinity.

From the above, the ethylene-based resin material has a high affinity with the ethylene-based low melting point crystalline material, and the low crystallinity of the resin material itself suppresses the crystal growth of the compound. Is necessary for. For this purpose, it is preferable that the ethylene-based resin material has a comonomer content of 25% by weight or more. Further, the copolymer of ethylene and the comonomer is preferably a random copolymer, and it is preferable that the monomer reactivity ratio of the comonomer is close to that of the ethylene monomer. As such a monomer, those having Q and e values of 1.0 or less, which are used as a measure of reactivity of the monomer, are preferable, and more preferable Q value is 0.2 or less. As such an ethylene resin material, a monomer copolymerizable with ethylene can be used as a binary copolymer or a terpolymer with ethylene. Such monomers include methyl methacrylate, etal methacrylate,
Monomers such as n-propyl methacrylate, iso-propyl methacrylate, methyl acrylate, ethyl acrylate, n-propyl acrylate, iso-propyl acrylate, acrylic acid, methacrylic acid, maleic anhydride, vinyl acetate, vinyl chloride, vinylidene chloride are preferable. is there.

The ethylene-based low melting point crystalline material is preferably a material having some other functional group in addition to the ethylene structure. Examples of such an ethylene-based low melting point crystalline material include organic substances having an ethylene crystal structure that melts at a predetermined temperature as shown below. That is,
Low molecular weight polyethylene wax, oxidized polyethylene wax, paraffin wax, oxidized paraffin wax,
Waxes based on carnauba wax, candelilla wax, rice wax, wood wax, beeswax, lanolin, coconut wax, oxidized wax ester, emulsion type wax, urethane type wax, alcohol type wax, amide wax, montan wax (Bleached montan wax, unbleached montan wax, refined wax, acid wax, ester wax, partially saponified ester wax), PO wax, rosin, rosin methylolated amide, ester gum, and higher fatty acid are exemplified.

Further, examples of the colorant which is a constituent material of the heat-fusible ink layer of the present invention include, for example, carbon black (Printex 25,35,150T, manufactured by Degussa), Vulcan First Yellow G (CI21095 (hereinafter, referred to as CINO
)), Benzidine Yellow G (21090), Pigment Yellow (11680), Permanent Pigment Red 5 (1
2490), permanent Bordeaux FRR (12385), benzidine orange (21110), resole red (15630), lake red C (15585), rhodamine 6G lake (45160),
Rhodamine B (45170), Phthalocyanine Blue (74160)
, Indian Brilliant Green B (59285), Phthalocyanine Green (74260), Quinacridone Red Y (4650
Pigments and dyes such as 0) and quinacridone magenta (73915) can be used if necessary.

The low melting point crystalline material, the resin material and the coloring material constituting the heat fusible ink layer of the heat-sensitive transfer recording medium of the present invention are not limited to the above-mentioned materials, but the low melting point crystalline material. Various materials can be used as long as the material and the resin material are compatible with each other and at least a part of them forms a compound. For example, as the resin material, in addition to the ethylene-based resin material, polyethylene resin, polyester resin, polyamide resin, polypropylene resin, polyvinyl butyral resin, ethylene-acrylic ester It is also possible to use a polymer resin, a styrene-acrylic acid ester copolymer resin, a styrene-maleic acid-acrylic acid ester copolymer resin, or the like.

The heat-sensitive transfer recording medium of the present invention comprises a sheet-like base material such as a polyester film obtained by applying a coating liquid obtained by dispersing the above-mentioned low melting point crystalline material, resin material, coloring material and the like in an organic solvent. It can be obtained by applying a heat energy to a material to form a wet coating film and then volatilizing the organic solvent to form a heat-meltable ink layer.
Further, the drying conditions for forming the heat-meltable ink layer affect the formation state of the compound, the shape of the compound, etc., and are therefore set according to the material used. That is, since the amount of heat energy required to obtain the heat-meltable ink layer varies depending on each material used and the thickness of the heat-meltable ink layer obtained, the optimum value is determined according to each case. To be done.

When forming the above-mentioned coating liquid, the mixing ratio of the above-mentioned ethylene-based low melting point crystalline material, ethylene-based resin material, coloring material, etc. is preferably set as follows.
In other words, the ethylene-based low melting point crystalline material has a weight ratio to the ethylene-based resin material of 1: 1 in order to be well compatible with the ethylene-based resin material and reduce the isolated portion of the wax that causes the stain. It is preferably in the range of to 3: 1. Further, the total amount is preferably in the range of 30 to 50% by weight.

Further, the content of the ethylene-based resin material is 20 to 20 in order to suppress the occurrence of reverse transfer, sticking, and stain, which are problems peculiar to a thermal transfer recording medium used a plurality of times.
It is preferably in the range of 30% by weight.

Further, if the amount of the colorant added is too large, it causes transfer failure, and if it is too small, the storage stability at high temperature is lost. Therefore, it is preferably in the range of 20 to 50% by weight. In addition, adding a large amount of expensive dyes or pigments as ink materials is contrary to the principle of providing good products at a lower cost, and therefore silica, silica sand, titanium oxide, zinc oxide, talc and other additives are added. It is also effective to add up to about 80% by weight of the colorant component.

[0028]

EXAMPLES Examples of the present invention will be described below.

Examples 1 to 15 and Comparative Examples 1 to 13 First, as ethylene low melting point crystalline materials, four types of ethylene low melting point crystalline waxes whose physical properties are shown in Table 1 were prepared. As ethylene resin materials, two kinds of ethylene resins having the physical properties shown in Table 2 were prepared. Carbon black pigment: P-1 (Printex 25, trade name, manufactured by Degussa) was used as the coloring material.

[Table 1]

[Table 2] The above-mentioned materials for forming the heat-meltable ink layer were first mixed in the composition ratios shown in Table 3 and dispersed for a predetermined time. The dispersion times are as shown in Table 3, respectively. Next, the obtained coating liquid was applied onto a polyester film having a back surface coated with a heat resistant active layer to form a coating film, followed by drying for a predetermined time to form a heat-meltable ink layer. The drying time is as shown in Table 3, respectively. In this way, thermal transfer recording media were produced.

Further, as a comparison with the present invention, a thermal transfer recording medium was similarly prepared by the composition ratio, dispersion time and drying time shown in Table 4.

[0031]

[Table 3]

[Table 4] The printing performance of the thermal transfer recording media of Examples 1 to 15 and the thermal transfer recording media of Comparative Examples 1 to 13 thus obtained was evaluated according to the following procedure. First, using a thermal transfer printer (Toshiba personal word processor JW-95HP, printing speed: 70 characters / second), a dedicated thermal transfer paper (Beck smoothness
The ribbon was rewound each time it was printed and printed repeatedly 5 times so that the kanji and solid black patterns could be printed at the same location every 400 seconds. By using the black solid pattern of the obtained transfer image, by Macbeth reflection image densitometer 1
The reflection image density of the second and third prints was measured. Next, the thermal transfer recording media of Examples 1 to 15 and Comparative Examples 1 to 13 were repeatedly printed and printed 10 times using the thermal transfer printer in an environment of a temperature of 35 ° C. and a humidity of 80%. By this printing running test, the high temperature running property of the thermal transfer recording medium was first examined, and the presence or absence of running defects such as sticking and bending was evaluated. Further, with respect to the obtained transfer printing, the presence or absence of tailing stain at the end of the print, the fog stain of the entire print, and the occurrence of reverse transfer were visually evaluated.

The results are shown in Tables 5 and 6.

[0033]

[Table 5]

[Table 6] In addition, a typical one was selected from the thermal transfer recording media according to the above-mentioned Examples and Comparative Examples, and each of them was
After cutting into a 5 mm square, both ends were fixed on a slide glass using adhesive tapes to prepare a sample for X-ray diffraction measurement. Using these X-ray diffraction measurement samples, the diffraction intensity of the hot-melt ink layer was measured by an X-ray diffractometer (manufactured by JEOL Ltd.). The X-ray diffractometer used, by mounting a jig for thin film measurement, reduces the diffraction angle of monochromatic X-rays relative to the sample surface (0.1 °) and reduces the scattered X-rays from the base material. In this case, it is possible to measure a diffraction peak which is buried in the background and cannot be discriminated.
With the above X-ray diffractometer, the diffraction peak intensity I (unit cps: count / sec) from the ethylene-based crystal and the diffraction angle 2θ at that time, and the halo intensity I _{0 of the} amorphous portion (incident angle: 16 ° to 17 °) Each) and measure the intensity ratio I / I
I asked for ₀ . The results are shown in Table 7.

[0034]

[Table 7] From the measurement results shown in Table 5, in the thermal transfer recording medium of the present invention, the image density of 1.0 or more was obtained in both the first printing and the third printing. This means that the thermal transfer recording medium of the present invention makes the low melting point crystalline material and the resin material compatible with each other, and the low melting point crystalline material forms a compound with the resin material, so that the printability is improved a plurality of times. It also shows that it is excellent in n-fold speed type printability. Similarly,
From the measurement results shown in Table 5, the heat-sensitive transfer recording medium of the present invention shows that even after repeatedly printing 10 times under high temperature environment,
Printing stains, reverse transfer, poor running, etc. did not occur. This is because the thermal transfer recording medium of the present invention has very few isolated portions of the low-melting-point crystalline material that cause printing stains. . From the measurement results shown in Table 7, it is understood that the thermal transfer recording medium of the present invention has a low diffraction peak intensity from the ethylene crystal. Since the ethylene-based low-melting-point crystalline material that is extremely easily crystallized has a low crystallinity, the low-melting-point crystalline material and the resin material are compatible in the heat-meltable ink layer in the heat-sensitive transfer recording medium of the present invention. And the low melting point crystalline material forms a compound with the resin material. Furthermore, when the surface and the fracture surface of the heat-sensitive transfer recording medium of the present invention were observed using an SEM, it was found that the surface and the fracture surface of the heat-meltable ink layer had irregularities.

On the other hand, as is clear from the measurement results shown in Table 6, in the thermal transfer recording medium of the comparative example, the first and 3
In the second print, the image density is below 1.0, and print stains, reverse transfer, and running defects are found. This is because in the thermal transfer recording medium of the comparative example, there is a portion where the ethylene-based low melting point crystalline material is crystallized by itself, which reduces the printability of multiple times and the n-fold speed printability, resulting in high-speed printing. Becomes difficult to respond to,
Further, it is considered that problems occurred in transferability and printing runnability in a high temperature environment. From the results shown in Table 7, the thermal transfer recording medium of Comparative Example has a higher diffraction peak intensity from the ethylene-based crystal than the thermal transfer recording medium of the present invention, and the low melting point crystalline material alone crystallizes. It can be seen that there is a part. Regarding this, when the surface and the fracture surface of the thermal transfer recording medium of the comparative example were observed by using SEM, the unevenness of the surface and the fracture surface of the heat-meltable ink layer as seen in the thermal transfer recording medium of the present invention was observed. No shape was observed, and a smooth surface with no irregularities and a fractured surface, which are considered to be crystallized by the low melting point crystalline material alone, were confirmed.

[0036]

As described above, according to the present invention, high-speed printing can be achieved, both the printing quality and the image density are satisfied, the surface of the recording medium to be transferred is not soiled, and the transferability is stable even at high temperature. Also, it is possible to provide a heat-sensitive transfer recording medium having print running properties and capable of obtaining a transfer image having no gloss, particularly a heat-sensitive transfer recording medium suitable for use a plurality of times or for n-fold speed type printing.

[0037]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nachio Nakamura 1 Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Inside the Toshiba Research Institute, Inc. (72) Inventor Tadayuki Nakamura 8 Shinsugita-cho, Isogo-ku, Yokohama-shi, Kanagawa Address Stock Company Toshiba Yokohama Office

Claims (2)

[Claims] 1. A heat-sensitive transfer recording medium comprising a sheet-shaped base material and a heat-meltable ink layer which is provided on the base material and selectively heated and melted to be transferred onto a transfer medium. The heat-meltable ink layer contains at least a low melting point crystalline material, a resin material and a coloring material, and the low melting point crystalline material and the resin material are compatible with each other, and the low melting point crystalline A thermal transfer recording medium, wherein at least a part of the material forms a compound with the resin material. 2. The heat-sensitive transfer recording medium according to claim 1, wherein the compound of the low melting point crystalline material and the resin material is dispersed in the heat fusible ink layer in the form of fine particles. Thermal transfer recording medium.