JPH1178264A - Thermal transfer recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal transfer recording method capable of forming a highly detailed image on image receiving paper low in surface smoothness. SOLUTION: In a thermal transfer recording method, the pre-print ink layer laminated on a base material in the order of an image receiving layer and a surface layer is thermally transferred to image receiving paper preliminarily by the thermal transfer recording method and color ink having an m.p. higher than that of the image receiving paper by 10-30 deg.C is thermally transferred to the image receiving layer of the pre-print ink layer transferred to the image receiving paper under the pressure of 600 g/cm or more of a recording head to form an image.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a thermal transfer recording method,
In particular, the present invention relates to a thermal transfer recording method capable of forming a high-definition image on an image receiving paper having low surface smoothness.

[0002]

2. Description of the Related Art Conventionally, in order to form a high-definition image by a thermal transfer recording method, an image receiving paper having a high surface smoothness has been required. For rough paper having low surface smoothness, a method is known in which a sealing ink is thermally transferred in advance and an image is formed thereon.

[0003] Japanese Patent Application Laid-Open No. 9-86058 by the same applicant.
Japanese Patent Application Laid-Open Publication No. H11-163873 proposes a technique for forming an image on a filling ink using a coloring ink having a melting point higher by 3 to 15 ° C. than the melting point of the filling ink, but the filling ink layer is a single layer. Therefore, how to prevent printing loss (occurrence of voids) of the filling ink layer due to voids and irregularities of the fibers of the image receiving paper, and how to ensure the transferability of the colored ink onto the filling ink layer, It was difficult to balance the filling performance and the transfer performance of the colored ink, and it was difficult to form a high-definition image on rough paper.

[0004]

SUMMARY OF THE INVENTION In view of the foregoing, the present invention provides a method for forming a color ink image after pre-printing a filling ink on an image receiving paper in advance. Thermal transfer recording method capable of preventing omission of printing of a filling ink (occurrence of voids), securing transferability of colored ink onto the filling ink, and forming a high-definition image on image receiving paper with low surface smoothness The task is to provide

[0005]

That is, the present invention provides:
(1) A preprint ink layer laminated on a base material in the order of an image receiving layer and a surface layer is thermally transferred onto an image receiving paper in advance by a thermal transfer recording method, and an image is received on the image receiving layer of the preprint ink layer transferred onto the image receiving paper. The present invention relates to a thermal transfer recording method, wherein a colored ink having a melting point higher by 10 to 30 ° C. than the melting point of a layer is thermally transferred under a recording head pressing pressure of 600 g / cm or more to form an image.

Further, according to the present invention, (2) the image receiving layer in the preprint ink layer has a melting point of 60 to 75 ° C. and a melt viscosity of 50.
５００500 cps / 90 ° C., penetration is 4-15, and the surface layer has a melt viscosity of 300-5000 cps / 90 ° C.
The thermal transfer recording method according to the above (1), wherein

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a two-layer preprint ink layer is transferred to an image-receiving paper having a low surface smoothness, whereby a relatively high melt viscosity surface layer in the preprint ink layer is used. In addition, since the gaps between the paper fibers and the fibers are buried, it is possible to eliminate the printing loss (the generation of voids) of the preprint ink layer and obtain a good sealing effect. Furthermore, on the relatively soft and low melt viscosity image receiving layer located on the surface layer after transfer of the preprint ink layer,
600 colored ink having a melting point higher than that of the image receiving layer by 10 to 30 ° C.
By embedding and transferring with a recording head pressing pressure of g / cm or more, sufficient printing performance can be obtained.

If the preprint ink layer has a one-layer structure, it is difficult to prevent printing loss due to paper fibers and voids between the fibers, and it is difficult to balance the transfer performance of colored ink, and it is difficult to ensure high-definition image quality. However, in the present invention, by separating the functions into a surface layer that is effective in preventing print omission due to paper fibers and an image receiving layer that improves the transferability of the colored ink, a good high-definition image can be obtained. Enabled formation.

If the melting point of the colored ink is higher than the melting point of the image receiving layer, but the difference is less than 10 ° C., satisfactory dot embedding performance in the image receiving layer during printing of the colored ink cannot be ensured.
Image quality decreases. On the other hand, if the temperature is higher than 30 ° C., the printing energy is excessively required, and the image receiving layer and the colored ink are crushed into a dot shape, resulting in deterioration of image quality. Conversely, if the melting point of the colored ink is lower than the melting point of the image receiving layer, the colored ink dots cannot be embedded in the image receiving layer, and a good image cannot be formed.

The melting point of the image receiving layer is preferably from 60 to 75 ° C.
If it is lower than this range, there is a problem in storage stability, while if it is higher than this range, the melting point of the colored ink needs to be further increased, so that there is a problem in the energy amount at the time of transfer.

In order to ensure good dot embedding performance of the colored ink, the image receiving layer has a melt viscosity of 50 to 500 cps.
/ 90 ° C, more preferably 60-300 cps / 90
It is desirable that the degree of penetration and the degree of penetration be 4 to 15. If the melt viscosity of the image receiving layer is less than the above range, the transferred dots are crushed, while if it is higher than the above range, the dot embedding performance is reduced. Further, when the penetration is less than the above range, the embedding performance of transfer dots is reduced, and when the penetration is higher than the above range, the dots are crushed.

The surface layer preferably has a melt viscosity of 300 to 5000 cps / 90.degree. C., more preferably 800 to 2000 cps / 90.degree. C., in order to prevent printing loss due to paper fibers. If the melt viscosity of the surface layer is less than the above-mentioned range, printing omission occurs, while if it is higher than the above-mentioned range, it is difficult to construct a recording medium.

When the printing pressure of the recording head is lower than 600 g / cm during the printing of the colored ink, the embedding of the colored ink in the image receiving layer becomes insufficient, so that good dots cannot be formed and the image quality deteriorates. Although the upper limit of the pressure of the recording head is not particularly limited, it is generally difficult for a printing apparatus to secure a head pressure of more than 1300 g / cm.

In the present invention, the preprint ink layer and the colored ink layer may be provided side by side on the same substrate.
They may be provided on separate substrates.

The thermal transfer recording medium of the embodiment in which the preprint ink layer and the colored ink layer are provided on the same base material (hereinafter referred to as embodiment A) is, for example, a preprinted ink medium having a predetermined size on the same base material. An ink layer and a single-color ink layer are alternately and repeatedly arranged. Monochromatic colored ink layers include black ink, red, blue, green,
Color inks such as yellow, magenta, and cyan are appropriately used.

To form an image on an image receiving paper using the thermal transfer recording medium, one of the preprint ink layers is superimposed on the image receiving paper and solid printed by a thermal transfer printer.
The preprinted ink layer is transferred onto an image receiving paper, and then a colored ink layer adjacent to the previously used preprinted ink layer is superimposed thereon, and the colored ink layer is transferred to an image to form an image. Next, the preprint ink layer adjacent to the previously used colored ink layer is superimposed on a new receiving paper,
Thereafter, image formation is performed in the same manner as described above. At that time, the colored ink layer is thermally transferred onto the preprint ink layer under the condition that the recording head pressing pressure is 600 g / cm or more. The preprint ink layer does not necessarily have to be printed on the entire surface of the image receiving paper, but may be printed on the same area as that of the color ink to be transferred later or a slightly larger area.

The thermal transfer recording medium of the embodiment A includes a medium in which a preprint ink layer, a yellow ink layer, a magenta ink layer, a cyan ink layer and, if necessary, a black ink layer are provided side by side on the same substrate. . This thermal transfer recording medium is suitably used for forming a color image using subtractive color mixture. As an example of the thermal transfer recording medium, a fixed size on the same substrate,
The pre-print ink layer, the yellow ink layer, the magenta ink layer, the cyan ink layer, and the black ink layer, if necessary, are repeatedly arranged in a certain order as one repeating unit. The order of arranging the ink layers in the repeating unit is appropriately determined in consideration of the transfer order of each color.

In order to form a color image on an image receiving paper using the thermal transfer recording medium, a preprint ink layer included in one repeating unit is superimposed on the image receiving paper and solid printed by a thermal transfer printer to perform preprinting. The ink layer is transferred onto the receiving paper, and then the yellow ink layer included in the same repeating unit is superimposed thereon, and the yellow ink layer is transferred in an image to form a yellow separation image, which is also included in the same repeating unit. The magenta ink layer and the cyan ink layer are sequentially transferred to form an image to sequentially form a magenta-decomposed image and a cyan-decomposed image, thereby forming a color image. Next, a color image is formed on a new image receiving sheet in the same manner as described above using the adjacent repeating units. At this time, each colored ink layer is thermally transferred onto the preprint ink layer under the condition that the recording head pressing pressure is 600 g / cm or more. Note that the preprint ink layer does not necessarily have to be solid printed on the entire surface of the image receiving paper, and may be printed in the same region as the printed color ink to be transferred later or in a slightly larger region.

In a thermal transfer recording medium of an embodiment in which a preprint ink layer and a colored ink layer are provided on separate substrates (hereinafter referred to as embodiment B), a preprint ink layer is provided on a first substrate. A combination of a thermal transfer recording medium and a thermal transfer recording medium in which a monochromatic colored ink layer is provided on a second base material may be used. Further, a thermal transfer recording medium having a preprinted ink layer provided on a first base material, and a thermal transfer recording medium having a yellow ink layer, a magenta ink layer, a cyan ink layer and, if necessary, a black ink layer arranged side by side on a second base material. Combination with a recording medium can be mentioned. In the latter combination, the yellow ink layer, the magenta ink layer, the cyan ink layer, and the optional black ink layer may be provided on different substrates.

The preprint ink layer in the present invention comprises:
It has a configuration in which an image receiving layer and a surface layer are laminated on a substrate in this order. As described above, the preferred image receiving layer has a melting point of 60.
７５75 ° C., melt viscosity 50-500 cps / 90 ° C., especially 60-300 cps / 90 ° C., penetration 4-1.
5, and the preferred surface layer has a melt viscosity of 300 to
5000 cps / 90 ° C, especially 800-2000
It is cps / 90 ° C.

The image receiving layer contains waxes as a main component, and may contain a thermoplastic resin if necessary.

Examples of the waxes include natural waxes such as lanolin, carnauba wax, candelilla wax, montan wax and ceresin wax; petroleum waxes such as paraffin wax and microcrystalline wax; oxidized wax, ester wax,
Synthetic waxes such as polyethylene wax, Fischer-Tropsch wax, α-olefin-maleic anhydride copolymerized wax; higher fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, and behenic acid; higher aliphatic acids such as stearyl alcohol and docosanol Alcohols; esters such as higher fatty acid monoglycerides, fatty acid esters of sucrose and fatty acid esters of sorbitan; one or more of amides such as oleylamide and bisamides can be used as appropriate.

The above-mentioned thermoplastic resin (including elastomer)
Examples thereof include olefin copolymer resins such as ethylene-vinyl acetate copolymer and ethylene-acrylate copolymer, polyamide resin, polyester resin, epoxy resin, polyurethane resin, acrylic resin, and vinyl chloride. Resin, cellulose resin, vinyl alcohol resin, petroleum resin, phenol resin, styrene resin, vinyl acetate resin, natural rubber, styrene
Butadiene rubber, isoprene rubber, chloroprene rubber,
One or more of polyisobutylene and polybutene can be used as appropriate.

The preprint ink layer according to the present invention comprises:
Since a colored ink image is formed thereon after transfer to the image receiving paper, it is usually preferable that the color of the portion where the preprint ink layer is transferred is substantially the same as the color of the image receiving paper. Therefore, in the present invention, it is preferable to make the preprint ink layer colorless and transparent or to color the same as the color of the image receiving paper. In order to make the preprint ink layer colorless and transparent, it is necessary to add substantially no colorant to both the image receiving layer and the surface layer. Is added. Since the papers of the image receiving paper are generally white, when a colorant is added to the image receiving layer, a white pigment or an extender is usually added. Of course, if the receiving paper is colored, carbon black, other inorganic,
Coloring agents such as organic coloring pigments and dyes may be added to color the image receiving paper in the same color. The preprint ink layer does not necessarily have to be the same color as the image receiving paper, and may be colored in a different color from the image receiving paper. As the white pigment or extender, for example, one or more of titanium oxide, silica powder, calcium carbonate, precipitated barium sulfate, magnesium carbonate, and alumina can be used.

In addition to the above components, compounding agents such as dispersants and optical brighteners can be appropriately added to the image receiving layer, if necessary.

The coating amount of the image receiving layer (the coating amount after drying, hereinafter the same) is suitably in the range of 3 to 10 g / m ² . If the coating amount is less than the above range, the dot embedding property at the time of printing the colored ink is reduced, and a good image tends not to be obtained. On the other hand, if it is larger than the above range, the dots tend to be crushed when printing the colored ink.

The surface layer is mainly composed of a thermoplastic resin, and may contain waxes if necessary. As the thermoplastic resin and the waxes, those similar to those in the case of the image receiving layer can be used.

In addition to the above components, a colorant, extender, dispersant, and the like can be appropriately added to the surface layer, if necessary.

The coating amount of the surface layer is suitably in the range of 3 to 15 g / m ² . If the amount of coating is less than the above range, print omission tends to occur. On the other hand, if it is larger than the above range, a step is formed at the boundary of the preprinted portion on the image receiving paper, and the appearance tends to be poor.

As the colored ink layer in the present invention, conventional ones can be used without particular limitation as long as the melting point is higher by 10 to 30 ° C. than the melting point of the image receiving layer. The coloring ink layer is composed of a coloring agent and a thermoplastic vehicle. As the thermoplastic vehicle, those composed of waxes and / or thermoplastic resins can be used.

As the wax and the thermoplastic resin, those similar to those in the case of the image receiving layer can be used.

As the coloring agent used in the coloring ink layer, various organic and inorganic pigments and dyes such as carbon black can be used.

As a yellow, magenta and cyan colorant used for forming a color image utilizing subtractive color mixture, a transparent colorant is preferably used.

As the yellow transparent coloring agent, for example, one or more of organic pigments such as benzidine yellow, benzidine yellow G, benzidine yellow GR, Hansa yellow 5G, and naphthol yellow S, and dyes such as auramine are used.

Examples of the magenta transparent colorant include Brilliant Carmine 6B and Brilliant Carmine B
One or more of organic pigments such as S, permanent red 4R, rhodamine lake B, quinacridone, and dyes such as rhodamine are used.

As the cyan transparent colorant, for example, one or more of organic pigments such as phthalocyanine blue and metal-free phthalocyanine blue and dyes such as Victoria blue are used.

Here, the transparent pigment means a pigment which gives a transparent ink when dispersed in a transparent vehicle.

Note that yellow, magenta and cyan 3
If it is difficult to obtain a clear black by subtractive color mixture by superposition of colors, for example, carbon black,
A black ink containing a black colorant such as a nigrosine base may be used. The black ink for such a purpose does not need to be transparent because it is not superimposed on the ink of another color. However, it is preferable that the black ink for the purpose of obtaining a color such as blue black, for example, which is superimposed on the ink layer of another color, is transparent.

The content of the coloring agent in the colored ink layer is preferably about 5 to 60% by weight.

The coloring ink layer may further contain a dispersant, an antistatic agent, and the like, if necessary.

The substrate in the thermal transfer recording medium of the present invention includes polyester films such as polyethylene terephthalate film, polyethylene naphthalate film, polyarylate film, polycarbonate film, polyamide film, aramid film, and other types of ink ribbon substrates. Various plastic films generally used can be used as the film.
Also, high-density thin paper such as condenser paper may be used. The thickness of the substrate is usually about 1 to 10 μm. Silicone resin, fluororesin, nitrocellulose resin, or various heat-resistant resins modified with these, such as silicone-modified urethane resin and silicone-modified acrylic resin, on the back surface of the base material (the surface that is in sliding contact with the recording head), or A conventionally known stick prevention layer made of a mixture of such a heat-resistant resin and a lubricant may be provided.

[0042]

Next, the present invention will be described with reference to examples.

Production Example 1 An image receiving layer ink having the following composition was applied to the front side of a 4.5 μm thick polyethylene terephthalate film having a stick prevention layer formed on the back side by a hot melt coating method, and the coating amount was 5 g / m 2. ^2. An image receiving layer (melting point 65 ° C., melt viscosity 150 cps / 90 ° C., penetration 8) was formed thereon, and a surface layer ink having the following composition was applied thereon by a solvent coating method, and dried to obtain a coating amount of 5 g / An m ² surface layer (melt viscosity: 1000 cps / 90 ° C.) was formed to obtain a thermal transfer recording medium A for preprinting.

Image-receiving layer ink component weight parts ethylene-vinyl acetate copolymer (softening point 65 ° C) 10 candelilla wax (melting point 68 ° C) 30 paraffin wax (melting point 65 ° C) 35 titanium oxide 20 dispersant 5 surface layer ink Component Weight part Ethylene-vinyl acetate copolymer (softening point 71 ° C) 30 Alicyclic hydrocarbon resin (softening point 125 ° C) 30 Carnauba wax (melting point 83 ° C) 40

Production Example 2 A heat transfer recording medium B for preprinting was obtained in the same manner as in Production Example 1 except that the image receiving layer was not formed and the coating amount of the surface layer was changed to 10 g / m ² .

Production Example 3 A heat transfer recording medium C for preprinting was obtained in the same manner as in Production Example 1, except that the coating amount of the image receiving layer was 10 g / m ² and the surface layer was not formed.

Production Examples 4 to 6 A colored ink having the composition shown in Table 1 was applied to the surface side of the film substrate used in Production Example 1 by a hot melt coating method, and a coating amount of 2.0 g / m ² was applied. Forming a colored ink layer having a melting point shown in FIG. 1, and forming a thermal transfer recording medium X for image formation;
I got Y and Z.

[0048]

[Table 1]

Example 1 and Comparative Examples 1 to 4 Using the thermal transfer recording media A, B, and C for preprinting, a thermal transfer printer (prototype) was used, and the recording head pressing pressure was 800 g / cm. The preprint ink layer was solid-transferred, and the colored ink layer was transferred thereon using the thermal transfer recording media X, Y, Z for image formation to form an image. The thermal transfer recording medium A for preprinting used,
Table 2 shows combinations of B and C and the thermal transfer recording media X, Y and Z for image formation.

The obtained image was visually observed, and the preprinted ink layer was evaluated for missing prints (voids) and the quality of the colored ink image. Table 2 shows the results.

[0051]

[Table 2]

[0052]

According to the present invention, in a method of forming a colored ink image after transferring a preprint ink layer onto an image receiving paper in advance, it is possible to prevent the preprint ink layer from missing printing on the image receiving paper having low surface smoothness. In addition, the transferability of the colored ink onto the preprint ink layer is ensured, and a high-definition image can be formed on an image receiving paper having low surface smoothness.

Claims (2)

[Claims] A preprint ink layer laminated on a substrate in the order of an image receiving layer and a surface layer is thermally transferred onto an image receiving paper in advance by a thermal transfer recording method, and the preprint ink layer is transferred onto the image receiving layer. , 10 to the melting point of the image receiving layer
A colored ink having a high melting point of 30 ° C.
A thermal transfer recording method, wherein an image is formed by thermal transfer under the above-mentioned recording head pressing pressure. 2. The image receiving layer in the preprint ink layer has a melting point of 60 to 75 ° C. and a melt viscosity of 50 to 500 cps / 90.
2. The thermal transfer recording method according to claim 1, wherein the degree of penetration is 4 to 15, and the surface layer has a melt viscosity of 300 to 5000 cps / 90.degree.