JPH0439087A - N-time mode thermal transfer method - Google Patents

Abstract

PURPOSE:To eliminate background staining or tailing at the time of printing and to enhance printing density or resolving power by constituting an ink layer so as to obliquely peel off the same with respect to a base material film. CONSTITUTION:In such a case that printing is applied to a transfer material C by heating the base material film 1 of a thermal transfer sheet A from the rear thereby by a thermal head B, when the feed speed of the transfer material C is made relatively higher than that of thermal transfer sheet A, an ink layer 2 is obliquely peeled off so that the ink layer (a) of the ink layer 2 is transferred to a printed character a' and the ink layer (b) of the ink layer 2 is transferred to a printed character b' and, therefore, printing with width L' is applied to the surface of the transfer material C with respect to the width L of the ink layer 2. At this time, when L'/L=2 is set, the consumption of the thermal transfer sheet A becomes half that of a usual thermal transfer method. In the same way, when L/L'=5 is set, the consumption amount of the thermal transfer sheet becomes 1/5.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to an N-times mode thermal transfer method, and more specifically to a thermal transfer method (hereinafter simply referred to as a The present invention relates to an N-time mode thermal transfer method which provides an image free from scumming, trailing, etc. during printing and which has improved print density, resolution, etc. in the N-time mode thermal transfer method.

(Prior art and its problems) Conventionally, when printing output prints from computers or word processors using a thermal transfer method, a thermal transfer sheet with a heat-melting ink layer provided on one side of a base film has been used. .

The above conventional thermal transfer sheet has a thickness of 1 as a base film.
Using paper such as capacitor paper or paraffin paper with a thickness of 0 to 20 μm, or plastic film such as polyester or cellophane with a thickness of 3 to 20 μm, a layer of heat-melting ink made by mixing coloring agents such as pigments and dyes with wax is applied. It is manufactured by coating.

One problem with the thermal transfer sheet described above is the economical problem in that printing can be performed only once at the same location, and therefore a thermal transfer sheet of the same width as the printing width is consumed.

A known method to solve this problem is to use a thermal transfer sheet for multiple printing, which can print multiple times at the same location, but with this method, the print density decreases with the number of times it is used. There is a problem in that it is difficult to print with uniform density.

Another method is an N-times mode method in which the conveying speed of the transfer material is made higher than the conveying speed of the thermal transfer sheet (both conveying methods may be in the same direction or in opposite directions).

In this method, the conveyance speed of the transfer material is N, and the conveyance speed of the thermal transfer sheet is N.

If N>N', the printing distance is N, but
The consumption amount of the thermal transfer sheet is N゛, for example, N=5,
If N° = 1, the consumption of thermal transfer sheet is 11
5, which is very economical.

However, in this method, the transfer material and the thermal transfer sheet move while being subjected to relative friction, which causes background smudges and trailing of the print on the transfer material, making it difficult to print with clear and high resolution. There's a problem.

One method to solve the background smudge problem is to form a colorless wax layer on the surface of the ink layer, but this surface layer is easily removed by friction and is not a sufficient solution. On the other hand, as a method to solve the problem of trailing, there is a method of forming the ink layer with a wax having a relatively high melt viscosity, but with this method, the ink layer does not wet well with the transfer material and the surface is rough like paper. In the case of the transfer material, voids (white spots) occur, making it difficult to print with high density and high resolution.

Therefore, an object of the present invention is to solve the above-mentioned drawbacks, and to provide an image that is free from scumming, trailing, etc. during printing and has improved print density, resolution, etc. even in the N-times mode method. An object of the present invention is to provide an N-fold mode thermal transfer method.

(Means for solving problems) The above objects are achieved by the present invention as described below.

That is, in the present invention, a thermal transfer sheet having a transfer ink layer that melts by heating is stacked on one side of a base film, and a transfer material, and the conveyance speed of the transfer material is set relative to the conveyance speed of the thermal transfer sheet. This N-time mode thermal transfer method is characterized in that the ink layer is peeled off diagonally from the base film in the N-time mode thermal transfer method, which is carried out in a large size.

(Function) In the N-time mode thermal transfer method, by peeling off the ink layer diagonally from the base film, there is no scumming or trailing during printing5, and the density and resolution of printing are improved. An improved image is provided.

(Preferred Embodiments) Next, the present invention will be explained in more detail with reference to preferred embodiments.

FIG. 1 is a diagram schematically explaining the method of the present invention. As shown in the figure, in the method of the present invention, when printing on a transfer material C by heating the base film 1 from the back side of the thermal transfer sheet with a thermal head B, the conveyance speed of the transfer material C is set to the thermal transfer sheet A. By setting the conveyance speed relatively higher than that of the ink layer 8 of the ink layer 2 as shown in the figure,
', the ink layer 2 is peeled off diagonally so that the ink layer is transferred to the print b'.

Since the ink layer 2 is peeled off diagonally in this way, a print with a width of L' is made on the surface of the transfer material C by the width of the ink layer 2. In this case, if L'/L=2, the amount of thermal transfer sheet A consumed will be half that of the normal thermal transfer method. Similarly L/L'
=5, the consumption amount of the thermal transfer sheet is 115.

Next, although the thermal transfer sheet used in the method of the present invention may be any conventionally known thermal transfer sheet, the structure of a thermal transfer sheet particularly suitable for the method of the present invention will be described below.

As the base film of the thermal transfer sheet, the same base film used for conventional thermal transfer sheets can be used as is, and other materials can also be used, and there is no particular restriction.

Specific examples of preferred base films include polyester, polypropylene, cellophane, polycarbonate, cellulose acetate, polyethylene, polyvinyl chloride,
Polystyrene, nylon, polyimide, polyvinylidene chloride, polyvinyl alcohol, fluororesin, chlorinated rubber,
Examples include plastic films such as ionomers, papers such as condenser paper and paraffin paper, nonwoven fabrics, and base films made of composites of these materials.

The thickness of this base film can be changed as appropriate depending on the material so that its strength and thermal conductivity are appropriate, but the thickness is preferably, for example, 2 to 25 μm.

In the present invention, a heat-melting ink layer is formed on the surface of the base film, preferably via a sensitizing layer, from an ink containing necessary materials.

The sensitizing layer is mainly formed from wax, but this wax layer may be colored with a coloring agent like the ink layer described later, or it may be colorless.

Representative examples of wax include microcrystalline wax, carnauba wax, paraffin wax, and the like. In addition, various waxes such as Fischer-Tropsch wax, various low molecular weight polyethylenes, wood wax, beeswax, spermaceti wax, privet wax, wool wax, shellac wax, candelilla wax, petrolactam, assorted waxes, fatty acid esters, fatty acid amides, etc. However, in the present invention, among the above waxes, those having a melt viscosity at 100° C. of 100 cps or less, preferably 50 cps or less are used. If the melt viscosity is too high, it will become similar to an ink layer, resulting in insufficient sensitization and voids. Such a sensitized layer has a thickness of 0.1 to 2 μm, preferably 0.5 to 1.5 μm.
It may be provided to have a thickness of approximately μm. If the sensitizing layer is too thin, the sensitizing effect will be insufficient, and if it is too thick, the sensitivity will decrease.

The ink layer provided on the sensitized layer is composed of a colorant and a vehicle, and may be supplemented with various additives as required. The colorant is preferably an organic or inorganic pigment or dye that has good properties as a recording material, for example, one that has sufficient color density and does not discolor due to light, heat, temperature, etc. Of course, colorants of various colors other than black, such as cyan, magenta, and yellow, can also be used.

In the present invention, in order to print N times as many characters using a relatively small area of the ink layer, it is necessary to set the colorant concentration of the ink layer to a relatively high concentration, and depending on the thickness of the ink layer,
In a preferred range of ink layer thickness of 3 to 20 μm, the preferred concentration is 20 to 70% by weight, more preferably 30 to 70% by weight.
It is in the range of 50% by weight, and if the concentration is too low, the print density will be insufficient, and if it is too high, the ink will not wet the paper easily and voids will easily occur, which is not preferable.

The vehicle used includes the above-mentioned wax as a main component, and mixtures of other waxes with drying oils, resins, mineral oils, cellulose, rubber derivatives, and the like.

The ink consisting of the above colorant and vehicle is preferably blended so that the melt viscosity at 100°C is 1000 cps or more, and wax alone has a melt viscosity of 100 cps or more.
If it is not possible to achieve 0 cps or more, various thermoplastic resins such as vinyl resins can be used in combination to increase the cohesive force and improve the melt viscosity. Usually, the melt viscosity can be increased to 10% by using vinyl resin at 7% by weight or more of the wax.
00 cps or more. A preferable melt viscosity is 100 to 5000 cps at 100° C. If the melt viscosity is too low, problems of scumming and trailing become noticeable, and if the melt viscosity is too high, voids are likely to occur. Furthermore, when a lubricant as described below is included in the ink layer, scumming and trailing can be improved.

The sensitized layer and the ink layer can be formed on the base film by hot melt coating, hot lacquer coating, gravure coating, gravure reverse coating, roll coating, and many other methods. Examples include a method of coating.

In the present invention, it is preferable to form an uncolored surface layer on the surface of the ink layer. This surface layer may be formed from wax as described above, or may be formed from the vehicle (medium) of the ink layer. It may be formed from a lubricant such as a lubricating wax, a silicone wax, a fluorine resin, a silicone resin, a higher fatty acid amide, an ester, a surfactant, or a thermoplastic resin in addition to these lubricants. It is preferable to use a lubricant or a resin layer in combination to improve the film strength, and it is also possible to use a two-layer surface layer consisting of a lubricant layer and a resin layer. By drying at a low temperature, a surface with minute irregularities remaining in the form of a single particle is formed.
- A thermal transfer sheet with excellent layer stain prevention properties can be obtained.

Incidentally, it is a matter of course that a layer for preventing sticking of the thermal head may be provided on the back surface of the above-mentioned thermal transfer sheet.

Since it goes without saying that the method of the present invention can be applied to thermal transfer sheets for color printing, multicolor thermal transfer sheets in which two or more colors are applied to the same base material are also included within the scope of the present invention.

The method of the present invention uses a thermal transfer sheet as described above, and is an N-fold mode method in which the conveyance speed of the transfer material is set higher than the conveyance speed of the thermal transfer sheet (both conveyance methods may be in the same direction or in opposite directions). be.

In this method, if the conveyance speed of the transfer material is N, and the conveyance speed of the thermal transfer sheet is N゛, and N>N', the printing distance is N, but the consumption amount of the thermal transfer sheet is N゛.For example, When N=5 and N°=1, the amount of thermal transfer sheet consumed is 115 compared to the conventional method, which is very economical.

(Effects) According to the present invention as described above, in the N-time mode thermal transfer method, by peeling off the ink layer diagonally from the base film, there is no scumming or trailing during printing. Furthermore, an image with improved print density, resolution, etc. is provided.

Furthermore, in a preferred embodiment, by using a thermal transfer sheet in which an ink layer is formed with a high melt viscosity and a sensitized layer with a low melt viscosity is formed between the ink layer and the base film, background smearing and scumming during printing are avoided. There is no trailing (and an image with improved print density, resolution, etc.) is formed.

(Example) Next, the present invention will be described in more detail with reference to Reference Examples and Examples. In the text, parts or percentages are based on weight unless otherwise specified.

Reference example 1 A slip layer was formed on the back side using a coating liquid with the following composition, thickness 6
．． 0 μm polyester film (product name: Lumirror J
The coating amount on the surface of Toshi ■ is 1.0 g/r.
rr (1, Oglrd corresponds to IBm. The same applies hereinafter) and apply the sensitized layer (melt viscosity at 100°C 28c).
ps) was formed.

I5 clothing and Kokokyu Zimei carnauba wax 30 parts nonionic surfactant 1 part isopropanol 100 parts water
30 parts Next, a composition having the composition shown below was heated at a temperature of 65°C, and applied to the surface of the sensitized layer at a coating amount of 8 g/d using a hot lacquer gravure coating method to form a thermal transfer ink layer (100°C). Melt viscosity 3000
cps) was formed.

Ink Ink Carnauba wax 20 parts Ethylene/vinyl acetate copolymer (Sumitate KA-10, manufactured by Sumitomo Chemical) 13 parts 150°F Paraffin wax 45 parts Carbon black
30 parts nigrosine dye
9 parts xylene 50 parts Improper tool 10 parts Next, the following composition was heated at a temperature of 60°C, coated with a hot lacquer gravure coating method at a rate of 2.0 g/I, and dried to form a surface layer. A thermal transfer sheet used in the present invention was obtained.

Oikeoki Riji Kokaidankai Ethylene/Vinyl Acetate Copolymer (Evaflex #46
0, Mitsui Polychemical ¥! J) 40 parts carnauba wax 20 parts 150'F paraffin wax 50 parts xylene
100 parts isoproper tool
10 parts Reference example 2 A coating liquid with the following composition was applied with a slip layer formed on the back side, and the thickness was 6.
．． 0 μm polyester film (product name: Lumirror)
1, Oglr
d (1.0 glrd corresponds to 1 μm. The same applies below)
Apply the sensitized layer (melt viscosity at 100°C: 28 cp).
s) was formed.

1 Equipment Rie Kaidankai Carnauba wax 30 parts Nonionic surfactant 1 part Isopropanol 100 parts Water
30 parts Next, a composition having the following composition was heated at a temperature of 100°C, and applied to the surface of the sensitized layer at a coating amount of 8 g/d using a hot melt roll coating method to form a thermal transfer ink layer (100°C). Melt viscosity 3000
cps) was formed.

Ink Ink Carnauba wax 20 parts Ethylene/vinyl acetate copolymer (Evaflex A-10, manufactured by Mitsui Polychemicals) 13 parts 150°F paraffin wax 45 parts Carbon black
30 parts nigrosine dye
9 parts Next, the following composition was heated at a temperature of 60°C, and 2.0 g/g was coated using a hot lacquer gravure coating method.
The thermal transfer sheet used in the present invention was obtained by coating and drying at a ratio of rd to form a surface layer.

Ethylene/vinyl acetate copolymer (Evaflex #46
0, manufactured by Mitsui Polychemicals) 40 parts carnauba wax 20 parts 150°F paraffin wax 50 parts xylene
100 copies of improv tool
10 parts Reference Example 3 The sensitizing layer was made of 150°F paraffin wax (melt viscosity at 100°C of 5 cps) containing 5% carbon black at 1.0 g/rr? A thermal transfer sheet used in the present invention was prepared in the same manner as in Reference Example 1 except that the sheet had a thickness of .

Reference Example 4 The sensitized layer had the following wax composition (melt viscosity at 100°C: 80c)
A thermal transfer sheet used in the present invention was prepared in the same manner as in Reference Example 1, except that the thermal transfer sheet was formed to a thickness of 1.0 g/A using 1.

Danyu Wataruza Kokaidan or Carnauba wax 19 parts Ethylene/vinyl acetate copolymer (Evaflex 210, manufactured by Mitsui Polychemicals) 1 part Isopropanol
60 parts water
100 parts Reference Example 5 The sensitized layer was made of the following wax composition (melt viscosity at 100°C: 50c)
A thermal transfer sheet to be used in the present invention was prepared in the same manner as in Reference Example 1 except that the sheet was formed to have a thickness of 1.0 g1rd using a heat transfer sheet (PS).

Takadama! Satoniji Dankai Carnauba Wax 19 parts Ethylene/vinyl acetate copolymer (Evaflex 210, manufactured by Mitsui Polychemicals) 0.5 parts Improper Tool
60 parts carbon black
10 parts water
100 copies of Reference Example 6 were obtained.

Examples 1 to 9 The thermal transfer sheets of the above-mentioned reference examples were printed using an N-time mode printing evaluation machine (N=6) and compared, and the results are shown in Table 1 below. Note that TRWI (manufactured by Kamijo Paper Industries) was used as the recording paper.

O: Good △: Slightly poor ×: Defective side, when the end of the peeled off part of the ink layer of the thermal transfer sheet after printing was observed with an optical microscope, the ink layer was peeled off diagonally as shown in the first figure. 150° F paraffin wax 45 parts carbon black
30 parts oil black
5 parts Reference Example 8 A composition having the composition shown below was heated at a temperature of 100°C and coated on the surface of the sensitized layer of Reference Example 1 in an amount of 8 g/r+? A thermal transfer sheet used in the present invention was obtained in the same manner as in Reference Example 1 except that a thermal transfer ink layer (melt viscosity at 100° C. of 2000 cps) was formed by coating at a ratio of .

- Ink Multi Ink set Carnauba wax 20 parts Ethylene/vinyl acetate copolymer (Sumitate KA-10, manufactured by Sumitomo Chemical) 10 parts 150''' F paraffin wax 45 parts Carbon black
25 parts Reference Example 9 5 parts of synthetic wax was added to each of the ink layer composition and surface layer composition of Reference Example 1, and in the same manner as in Reference Example 1, the thermal transfer sheet used in the present invention was prepared with a sensitized layer. 1.5 using the following wax composition (100°C melt viscosity 16 cps)
A thermal transfer sheet for use in the present invention was prepared in the same manner as in Reference Example 1 except that it was formed to a thickness of g/a.

15 parts Riie Kaijioku Candelilla Wax 30 parts Surfactant for emulsion formation 1 part Improper Tool 50 parts Water
50 parts Reference Example 7 A composition having the following composition was heated at a temperature of 100°C and applied to the surface of the sensitized layer of Reference Example 1 using a hot melt roll coating method at a coating amount of 8 g/rd to form a thermal transfer ink. layer(
A thermal transfer sheet used in the present invention was obtained in the same manner as in Reference Example 1, except that the sheet had a melt viscosity of 4,500 cps at 100°C.

Ink Ink Carnauba wax 20 parts Ethylene/vinyl acetate copolymer (Sumitate KA-10, manufactured by Sumitomo Chemical) 20 parts.

In addition, in the present invention, the melt viscosity of the sensitized layer is HAAKE
With a viscometer (Rotovisco, M-500) manufactured by
Sensor MV-1 and share rate 256 (1/s)
The melt viscosity of the ink layer and surface layer was measured using a viscometer (Rotovisco) manufactured by HAAKE.
, PK-100), sensor PK 5-0.5°
(cone plate) and share rate 512 (1/s
) is the value measured.

[Brief explanation of drawings]

FIG. 1 is a diagram schematically explaining the method of the present invention. A: Thermal transfer sheet B: Thermal head C: Transferred material
l: Base film 2: Ink layer and 1 other person

Claims (6)

[Claims] (1) Layering a thermal transfer sheet having a transfer ink layer that melts by heating on one side of a base film and a transfer material,
An N-time mode thermal transfer method in which the conveyance speed of the transfer material is relatively higher than the conveyance speed of the thermal transfer sheet, and the N-time mode is characterized in that the ink layer is peeled off diagonally from the base film. Thermal transfer method. (2) A sensitized layer is formed between the base film and the ink layer, and the melt viscosity of the ink layer is 1000c at 100°C.
The N-time mode thermal transfer method according to claim 1, wherein the sensitized layer has a melt viscosity of 100 cps or less at 100°C. (3) The N-time mode thermal transfer method according to claim 1, wherein the pigment concentration of the ink layer is 20 to 70% by weight. (4) The N times mode thermal transfer method according to claim 1, wherein the thickness of the ink layer is in the range of 3 to 20 μm. (5) The N-time mode thermal transfer method according to claim 1, wherein the ink layer is formed using wax and a thermoplastic resin as a vehicle. (6) The N-times mode thermal transfer method according to claim 1, wherein an uncolored surface layer is formed on the surface of the ink layer.