JPS63168378A - Thermal transfer ink medium - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal transfer ink medium used in a thermal transfer printing device that forms an image by controlling the application of thermal energy.

[Conventional technology]

Thermal transfer printers are small, low-cost, non-impact printers that can be used for information processing terminals and word processors.

It is widely used in fields such as copiers. A conventional thermal transfer ink medium used in a thermal transfer printer has a structure in which ink layers 3 and 2 are provided on a heat-resistant support layer 31, as shown in FIG. 3(α). PIT, condenser paper, etc. are mainly used as the heat-resistant support layer.

The ink layer is provided by coating the heat-resistant support layer with a colored thermoplastic ink obtained by adding a dye or pigment to a thermoplastic substance such as wax or polymer using a solvent or a hot melt method.

Furthermore, a structure shown in FIG. 5cb> has also been proposed.

31 is a heat-resistant support layer, 32 is an ink layer, and 53 is a polymer-rich ink layer.

[Problem that the invention seeks to solve]

However, with conventional technology, transfer paper with poor surface smoothness (
The paper (hereinafter referred to as No. 7 paper) had a problem in that the ink transfer efficiency was poor and the print quality was degraded. The cause will be explained below.

FIG. 4 shows the force that acts on the ink portion 45 to be transferred when the ink film 41 is peeled off from the transfer paper 44 after applying heat in the thermal transfer printing method, in which 43 is the ink layer and 42 is the heat resistant Showing the support layer.

FA (ink-to-transfer paper adhesion force), which is the promoting force for transferring the recording part ink to the transfer paper, and ys (ink cohesive force), and the force that hinders transfer, 70 (ink-coupe-to-film adhesion force) ) and yo (cohesive force between recording part ink and non-recording part ink), 7B, ? M)'1!0. 'HD
If the relationship always holds true, transcription is complete.

However, when transferring to rough paper, as shown in FIG. 5(α), the ink contacts the convex portions (A) on the surface of the rough paper 55, but does not contact the concave portions (B). When the recording section ink 54 is heated, the molten ink adheres to the paper in the A section, but remains unadhered in the B section.

In the figure, 51 is a thermal head, 52 is a heat-resistant support layer, and 5 is a thermal head.
3 is an ink layer. Furthermore, since the ink in the recording area that is not in contact with the paper is suppressed from conducting heat to the paper, it becomes hotter than the ink that is in contact with the paper, creating a surface tension gradient that causes it to flow in the direction of the contact area. As shown in Figure 5 cb, the molten ink flows into the contact area (for example, paper fibers) (section C in the figure), and the ink in the non-contact area becomes very thin (Fig. When the ink film is peeled off in this state, the ink in the recording area that is in contact with the paper is transferred to the paper, and the ink in the recording area that is not in contact with the paper is transferred to the paper, as shown in FIG. 5(c). It becomes a thin film and remains on the film side. The main reason why part 7 remained on the film is:
A temperature difference occurred within the recording section, causing ink flow, making the film thickness uneven, and because the cohesive force of the ink (?m in Figure 4) was small, shear failure of the ink occurred within the recording section ink. It is.

As a countermeasure to these problems, conventional technology has adopted a method of adding polymers or inorganic substances to the ink to suppress the flow of the ink and increase the cohesive force. There was a problem in that the cohesive force between the ink in the recording area and the ink in the non-recording area as shown in A D became strong, making it difficult to cut pixels. Furthermore, as shown in FIG. 3(b), there is a method of suppressing the flow of ink by providing a polymer-rich layer 53 below the ink layer, but in this case, the melting point and melt viscosity of the polymer-rich layer are As a result, there were problems in that the printing energy was increased and the adhesive force with the paper (FIG. 4, 1 person) was reduced.

In addition, with conventional thermal transfer ink media, when transferred to rough paper, voids (
In addition, as shown in FIG. 6, the uneven surface of the recording ink 610 transferred to the paper 62 causes diffused reflection, which lowers the optical density and deteriorates the quality. There was.

The present invention was made to solve these problems, and its purpose is to print two high-density, high-quality character images even on rough paper with poor surface smoothness. An object of the present invention is to provide a thermal transfer ink medium that allows printing without increasing printing energy.

[Means for solving problems]

The ink medium of the present invention is characterized by comprising at least a heat-resistant support layer, a first ink layer, an intermediate layer, and a second ink layer. Furthermore, the first ink layer has a melting point or softening point of 40
The second ink layer is a thermoplastic material having a melting point or softening point within the range of 50°C to 200°C.
A thermoplastic material having a temperature within the range of 150°C, and
The intermediate layer is characterized by being made of a thermoplastic material or a thermosetting material having a melting point or softening point of 40° C. or higher. Furthermore, the intermediate/7 is characterized in that it does not flow when heat is applied. Furthermore, the thickness of the heat-resistant support layer is 1 to 12 μm, the thickness of the first ink layer is 1 to 3 μm, and the thickness of the intermediate layer is 01 to 3 μm.
m, the thickness of the second ink layer is 2 to 10 μm.

[Effect]

The effect that the thermal transfer ink medium according to the present invention can transfer high-quality character 9 images to rough paper will be explained.

FIG. 1 shows a cross-sectional view of a thermal transfer ink medium according to the present invention. 11 is a heat-resistant support layer, 12 is a first ink layer,
13 is an intermediate layer, and 14 is a second ink layer. FIG. 2 shows the state of ink transfer when printing on rough paper using this thermal transfer ink medium. In FIG. 2, 21 is a thermal head, 22 is a thermal transfer ink medium, and 23 is rough paper.

In the figure, 24 is a heat-resistant support layer, 25 is a first ink layer, 26 is an intermediate layer, and 27 is a second ink layer. In FIG. 2(α), when heat is applied to the recording part ink 28 by the thermal head, the recording part ink of the second ink layer causes flow, as shown in FIG. Infiltrate the department.

That is, it is glued to paper. At this stage, the intermediate layer does not flow, so the ink in the recording part of the first ink layer also does not flow. In other words, the ink in the recording part of the first ink layer is spread over the intermediate layer with a uniform thickness. Keep it stacked.

When peeling off the ink film, see Figure 2 (CC)
As shown in the figure, the recording portion of the first ink is transferred to the paper together with the intermediate layer while remaining in a flat film state. 'Here, the part of the second ink layer that is not in contact with the paper (D in the figure) has become a thin film due to flow, but the entire recording part ink is transferred to the intermediate layer and the first ink layer.
Because the ink layer is reinforcing, 1 in Figure 5(c) mentioned above
Transfer defects such as those shown in Fig. 1 do not occur.

That is, the entire recording section ink is transferred. (29 in the diagram
). Furthermore, since the intermediate layer is thin, it does not increase the cohesive force between the ink in the recording area and the ink in the non-recording area as shown in FIG. Furthermore, since the recording portion ink of the first ink layer transferred to the paper does not penetrate into the paper and the surface is flat, the optical density of the print is extremely high.

〔Example〕

A cross-sectional view of the thermal transfer ink medium according to this example is shown in FIG. 11 is a heat-resistant support layer, 12 is a first ink layer, 13 is an intermediate layer, and 14 is a second ink layer. As the heat-resistant support layer, condenser paper, PIT, PleS, PE! K.K.
, PPS, polyimide.

A heat-resistant polymer film such as polyamideimide or polycarbonate having a melting point preferably has a melting point of 150° C. or higher. The thickness is 1 μm or more to provide thermal and mechanical strength as a medium, and to increase heat transfer efficiency.
In order to reduce the loss of energy required to activate the ink, the thickness is preferably 12 μm or less.

The first ink layer plays a main role in visualizing the character 2 image information from the thermal element, and is a thermoplastic material layer containing dyes and pigments. This ink material preferably has a melting point or softening point of 40°C or higher in order to improve the sharpness of printed pixels and prevent bleeding during storage. The temperature is preferably 200° C. or higher to prevent the film from sticking to the thermal element. As the binder, waxes such as natural wax, petroleum wax, synthetic wax, fatty acid amide, fatty acid ester, ETA, Em
A. Polyvinyl alcohol.

Methylcellulose, carboxydimethylcellulose, styrene-butadiene copolymer, methylmethacrylic resin,
Silicone resin', II? Single polyethylene, styrene-acrylic copolymer, acrylic resin, tristyrene, etc.
Alternatively, mixtures can be used. The content of dyes and pigments is preferably 1 to 50 wt%. In order to sharpen the temperature dependence of the melt viscosity of the ink and improve the sharpness of pixels, the wax content in one binder is 50W.
It is desirable to make it t% or more. The thickness of the ink layer is desirably 1 .mu.m or more in order to increase the optical density per character stroke, and 5 .mu.m or less in order to reduce printing energy.

The intermediate layer serves to prevent the ink from flowing in the direction of the transfer paper in the first ink layer when heat is applied, and to transfer the layer to the transfer paper with a uniform layer thickness. It is a thin film that is transparent or colored as necessary, and is mainly composed of a type of organic substance. The film thickness should be 0.1 μm or more to prevent the first ink layer from flowing when heat is applied, and the cohesive force between recording area ink and non-recording area ink (Figure 4) 1IID) should be maintained when the film is peeled off after heat application. In order not to increase the thickness of the pixel, that is, to improve the sharpness of the pixels, it is desirable that the thickness be 3 μm or less. As the binder, thermoplastic substances such as waxes and polymers similar to those used in the first ink layer, phenol resin, melamine resin, area resin, unsaturated polyester resin, epoxy resin, etc. can be used.

Liimide, silicone resin, alkyd resin, V-tan resin,
The main component can be a thermosetting substance such as casein resin. Since it is necessary that the intermediate II layer does not flow when heat is applied, when a thermoplastic substance is used as the main component of the binder, it is desirable that the wax content is 3 owt% or less.

Furthermore, in order to make the intermediate layer brittle and improve pixel sharpness, it is effective to add inorganic substances such as carbon dioxide, titanium oxide, and carbon black. Furthermore, if necessary, dyes and pigments can be added for coloring.

The second ink layer plays the role of adhering the first ink layer and the intermediate layer to the transfer paper, and is mainly composed of a thermoplastic material. This ink material preferably has a melting point or softening point of 50°C or higher in order to improve the sharpness of printed pixels and prevent blocking and bleeding during storage.It also reduces printing energy and prevents adhesion to the transfer paper. The film thickness is desirably 150° C. or less in order to increase the strength, and the film thickness is desirably 2 μm or more in order to strengthen the adhesive force with the transfer paper, and 10 μm or less in order to lower the printing energy. The content of waxes in the binder is desirably 40 wt% or more in order to improve the fixability of the ink to the transfer paper. In addition, if no coloring material is added to the second ink layer, after printing, the first
The ink layer and intermediate layer can be peeled off and collected from the receiving paper, and if a colorant is added, it can be made into a tamper-proof thermal transfer ink medium.

<Example 1> The cross-sectional structure of a thermal transfer ink medium according to this example is shown in FIG.

The heat-resistant support layer was made of PET with a thickness of 4 μm.

The first ink layer was obtained by coating PET with the composition shown below to a thickness of 3 μm using a hot melt method.

[First ink layer composition] Paraffin wax 40 (vt%) Microcrystalline wax 50 Polyethylene
10 7/EXA
5 (wt%) TiVA

5 //Carbon black 10
[The melting point of the first ink layer is 70°C. The middle layer is polystyrene toluene-MIK (methyl ethyl ketone)
The mixed solution was coated on the first ink layer by a solvent gravure method to give a dry film thickness of 0.5 μm. The second ink layer had the composition shown below and was coated on the intermediate layer by a hot melt-solvent method to give a film thickness of 4 μm.

[Second ink layer composition] Paratwin wax 50 (wt%) Carnauba wax 25 l Liethylene
10 〃EVA 1
5 # The melting point of the second ink layer was 65°C.

Thermal transfer printing was performed using the thermal transfer ink medium obtained as described above. A block diagram of the printing device is shown in FIG. 2 (α). Thermal head 51 has a resolution of 180D
A thin-film thermal head manufactured by P. Co., Ltd. was used. 22 is a thermal transfer ink medium according to this embodiment. 24 is PFXT, 25 is a first ink layer, 26 is an intermediate layer, and 27 is a second ink layer. As the transfer paper 23, a cotton paper with a Beck smoothness of 2 seconds was used. To evaluate the printing quality, 100 dots were printed in dot units, and the variation in dot area was expressed as standard deviation, with the area of the heating element as 1. The print density was determined by performing solid printing and measuring O and D. The printing energy was normalized and compared by setting the energy required to produce the highest density as 1 when using a thermal transfer ink medium with a conventional structure (Comparative Example 1 described below). The evaluation results are shown in Table 1.

<Example 2> The cross-sectional structure of the thermal transfer ink medium according to this example is as in Example 1.
It is similar to

The heat-resistant support layer was made of PET with a thickness of 4 μm, and the first ink layer was formed on PFiT having the composition shown below to a thickness of 2 μm.

, [First ink layer composition] Paraffin wax 60 (wt%) Maleic anhydride copolymer 20 (wt%) Vinyl acetate
5 FXEA
5 #Carbon black 10
[The melting point of the first ink layer is 85°C.

The intermediate layer was formed by solvent coating a mixture of phenoxy as a main component and incyanate as a crosslinking agent, which was melted in a mixed solvent of toluene, MEK, and MIBK, dried, and then subjected to air ringing at 50°C for 24 hours. did. The film thickness is cL2 μm. The second ink layer was obtained by hot-melt coating the composition shown below to a thickness of 5 μm. The melting point of the second ink layer is 55° C. [Second ink layer composition] Carnauba wax 35 (wt%) Polyethylene 30 〃11iKA
20 #Carbon black
15 The printing evaluation method was the same as in Example 1.

<Example 3> The cross-sectional structure of the thermal transfer ink medium according to this example is as in Example 1.
It is similar to

The heat-resistant support layer was made of PET with a thickness of 3 μm, and the first ink layer was obtained by coating the composition shown below to a thickness of 5 μm.

[First ink layer composition] Microcrystalline wax so (wt%) Modified (polar) wax 25 Polyvinyl alcohol 5 ETA
I5 11 carbon black 10
The melting point of the first ink layer is 45°C.

The intermediate layer was coated with Anlyl emulsion carbon having a softening point of 80° C. and had a dry film thickness of 1 μm.

The second ink layer had the following composition and was formed to have a thickness of 3 μm. The melting point of the second ink layer is 70°C.

[Second ink layer composition] Paraffin wax 20 (wt%) Maleic anhydride copolymer 50 (vrt%) Polyethylene
10 〃1! iKA
10tt]! tVA 1
0 #Evaluation method is the same as in Example 1.

Comparative Example 1 The thermal transfer ink medium according to this comparative example is of the prior art,
The structure is shown in FIG. 3 (α).

The heat-resistant support N51 was made of PET with a thickness of 4 μm. The ink layer 32 was formed by coating the same composition as the first ink layer of Example 1 to a thickness of 6 μm.

The evaluation method was the same as in Example 1.

Comparative Example 2 The thermal transfer ink medium according to this comparative example had the same structure as that of comparative example 1, and the heat-resistant support layer used PIT with a thickness of 3 μm on each corner. The ink layer was formed with an ink having the same composition as the first ink layer of Example 2 to a thickness of 8 μm.

The evaluation method was the same as in Example 1.

<Comparative Example 3> The cross-sectional structure of the thermal transfer ink medium of this comparative example is that of the conventional structure shown in FIG. A layer similar to Example 3 was coated to a thickness of 5 μm.The polymer-rich ink layer 33 was coated with the following composition to a thickness of 2 μm.The softening point of the polymer-rich ink layer was The temperature is 60°C.

[Polymer rich ink layer composition]

Paraffin wax 30 (wt%) Geliethylene 20 pEXA
20 WZVA
50z The evaluation method is the same as in Example 1.

〔Effect of the invention〕

As described above, the thermal transfer ink medium according to the present invention has the following advantages when compared to the prior art when transferred to a receiving paper with poor surface smoothness.

1. Since there is little variation in the transfer dot area and the printing density is high, it is possible to print high quality characters and images.

Z Printing energy can be reduced.

Therefore, it is possible to dramatically expand the application range of thermal transfer printers using the thermal transfer ink medium according to the present invention.

Further, in this example, carbon black was used as the coloring material added to the first ink layer and the second ink layer, but it is also possible to add other organic pigments, inorganic pigments, dyes, etc. to make them colored.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the thermal transfer ink medium of the present invention. FIGS. 2(α), (b), and (C) are diagrams showing the principle of thermal transfer using the thermal transfer ink medium of the present invention. FIGS. 3(a) and 3(b) are cross-sectional views of a conventional thermal transfer ink medium. FIG. 4 is a diagram showing the transfer principle of a conventional zero-thermal transfer ink medium. FIGS. 5(α), (A), and (c) are diagrams showing the principle of transfer of conventional thermal transfer ink media. FIG. 6 is a diagram showing a printing state using a conventional thermal transfer ink medium. Applicant Seiko Epson Co., Ltd. ((C) (C') Figure 6 Procedural Amendment (Voluntary) July 24, 1985 Patent Application No. 310236 No. 2, Name of Invention Thermal Transfer Ink Sheet 3, Relationship with the person making the amendment Patent applicant!! 2-4-1 Nishi-Shinjuku, Shinjuku-ku, Kyoto (236) Tsuneya Nakamura, Representative Director of Seiko Even Co., Ltd. 4, Agent 112 Telephone 03 ( 815) 6100
6. Contents of correction (1) 8% of details will be corrected as shown in the attached sheet. (2) Amend the drawings by attaching a separate sheet. Description 1, Name of the invention Ink sheet for thermal transfer 2, Claims A first heat-melting ink layer mixed with a colorant on a heat-resistant support film, and a low melting point ink layer whose viscosity decreases with temperature. An ink sheet for thermal transfer, which is formed by laminating an intermediate layer made of a material and a second heat-melting ink layer. 3. Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an ink sheet used in a thermal transfer recording device, which is made of a heat-melting ink and a heat-resistant film supporting the ink. (Prior art) A so-called thermal transfer recording device that applies heat energy to melt and transfer heat-melting ink onto a recording medium according to recorded information usually coats one side of a heat-resistant film with heat-melting ink. A ribbon-shaped or web-shaped ink sheet is used. However, when trying to record on recording paper with a rough surface (hereinafter referred to as rough paper) using this type of ink sheet, the fourth
As shown in Figure (a), ink b contacts only the convex portions of the surface of the rough paper S, so if ink b is heated in the area to be recorded in this state, it will be deposited in the concave portions and will not come into contact with the paper. As a result of heat conduction being suppressed, the ink in this state becomes hotter than the other parts and flows toward the contact area, and therefore, when Film C is peeled off in this state (Fig. 4 (b)), it becomes a rough paper. Not only will more ink be transferred to the convex portions of the S surface than elsewhere, resulting in defective transfer of pixels in the recording section called voids, but the unevenness of the ink on the surface will cause diffuse reflection of light, reducing the optical density of the image. decrease. On the other hand, if ink with low fluidity is used to prevent the ink from flowing into the contact area, more heat energy than necessary is required for transfer, and the adhesive strength with the paper is reduced. This causes other problems such as a decrease in (Objective) The present invention has been made in view of the above-mentioned problems, and its object is to reduce the surface smoothness of recording media (
Another object of the present invention is to provide a new ink sheet that can form a highly dense and uniform recorded image with relatively little thermal energy. (Means for Achieving the Object) That is, the present invention provides an ink sheet for achieving the object, including a first heat-melting ink layer mixed with a colorant on a heat-resistant support film, and a temperature-dependent ink layer. It is formed by laminating an intermediate layer made of a low-melting point material with a small decrease in viscosity and a heat-melting second ink layer. (Example) The details of the present invention will be described below based on illustrated examples. The ink sheet shown in FIG. 1 constitutes one embodiment of the present invention, and this ink sheet 1 consists of a heat-resistant support film 11, which has wax as its main component, and which is coated with paint or pigment. mixed first ink layer in the heat melting chamber] 2, an intermediate layer 13 mainly composed of a low melting point thermoplastic resin,
It is constructed by laminating a heat-melting second ink layer 14 whose main component is wax. The above-mentioned heat-resistant support film 11 forming the base of the ink sheet 1 has a film thickness of about lum to 12 um from the viewpoint of thermal and mechanical strength and thermal conductivity, and is made of, for example, capacitor paper, PET, PES, PEEK, etc. It is constructed as a thin film made of PPS or a heat-resistant polymer such as polyimide, polyamideimide, or polycarginate. Further, when the first ink layer 12 supported on the support film 11 receives thermal energy from the thermal head h, it melts in units of one pixel while being supported by an intermediate layer 13, which will be described later, and the film It peels off from 11 and adheres to the recording paper S, and plays the role of expressing a visible image according to the recorded information. The viscosity, melting point, layer thickness, compounding material, etc. are selected from the viewpoint of reducing the required thermal energy as much as possible and ensuring the required optical density. As a binder, waxes such as natural wax, petroleum wax, and synthetic wax, fatty acid amide, fatty acid ester, EVA, EEA, polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, styrene-butadiene copolymer, and methyl methacrylic are used as binders. Resin, silicone resin, polyethylene,
Styrene-acrylic copolymer, acrylic resin, polystyrene, etc. are used singly or as a mixture, and the temperature dependence of the melt viscosity of the ink is steepened (Fig. 3).In order to improve pixel sharpness, Wax content: 50w
t% or more, and dye in a proportion of 1 to 50 wt%,
It is desirable to contain a pigment, and the melting point is 40°C.
It is desirable that the temperature is in the range of 200° C. and the layer thickness is 1 um to 5 um. On the other hand, the intermediate layer 13 serves to prevent the ink of the first ink layer 11 from flowing in the direction of the recording paper S when heat is applied, and to transfer the ink while maintaining a uniform layer thickness. It is necessary to achieve good separation between the intermediate layer 13 in the non-recording area (FIG. 3) and the adjacent non-recording area. The main component is the same thermoplastic material as layer 11, and 30W is used to prevent it from flowing when heat is applied.
It is desirable to contain waxes of t% or less and to add inorganic substances such as charcoal, titanium oxide, and carbon black in order to improve the sharpness of pixels, and the layer thickness is 0.1 μm to 5 μm. The temperature is set so that softening starts at a low temperature of about 50°C to 150°C. On the other hand, the second ink layer 14 laminated on the top mainly serves to adhere the first ink layer 12 and the intermediate layer 13 to the recording paper S, and the ink material for this ink layer is the M1 ink layer. Using thermoplastic substances such as waxes and polymers similar to No. 12, it prevents breakage between ink in adjacent non-recording areas, blocking and bleeding during storage, reduces printing energy, and has adhesive strength with recording paper S. In order to increase the ink, the melting point should be in the range of 50'C to 150'C, the film thickness should be in the range of 2um to 10μm, and the content of waxes in the binder should improve the fixability of the ink to the recording paper S. Tame 4
It is desirable that the coloring agent be 0 wt % or more. It is not necessarily necessary to add the colorant lFr to this layer 14, and if it is not added, the first ink layer 12 and the intermediate layer 13 are simply scraped off from the recording paper S after printing. This makes it easy to correct the recording, and if a colorant is added, it can be configured as a tamper-proof thermal transfer ink. Next, using the ink sheet 1 configured in this way,
The operation when recording and transferring to recording paper S with a rough surface will be explained. First, when heat is applied to the ink sheet according to the recording information by the thermal head h, the recording part ink of the second ink layer 14 melts and flows along the recording paper S, and a part of it flows along the recording paper S. Penetrates into the fibers at the contact point. On the other hand, as shown in FIG. 3, the intermediate layer 13 is mainly composed of a thermoplastic resin whose viscosity decreases little due to temperature.
During this heat application process, the layered state is maintained without flowing,
1st ink layer] 2 recording part ink continues to be maintained in a layered state with a uniform thickness without flowing (see Fig. 2 (a)
)). Therefore, when the support film 11 is then peeled off from the recording paper S in this state, the recording area ink of the first ink layer 12 remains uniform as shown in FIG. 2 (1)). It is transferred to the recording paper S together with the intermediate layer 13, and
In this state, the second ink layer 1 becomes thinner due to the flow.
Since the ink 14a in the non-contact area of No. 4 is also supported by the intermediate layer 3 and transferred onto the recording paper S, a flat ink layer with an area corresponding to the pixels of the recording section is uniformly formed on the recording paper S. Ru. [Example 1] On a heat-resistant support film made of PET with a thickness of 4 um,
Paraffin wax 40wt%, microcrystalline wax 30wt%, polyethylene 10wt%, EEA
5wt%, EVA5wt%, carbon black 10wt
A first ink layer having a melting point of 70'C and having a composition of
An intermediate layer is formed by coating a polyester toluene-methyl ethyl ketone mixed solution with 30 wt% of solid titanium oxide added thereto to a dry film thickness of 0.5 μm using the solvent gravure method, and then roughly coated with paraffin wax on top of this intermediate layer. 50wt%, carnauba wax 25
wt%, polyethylene 10wt%, EVAl 5wt%
A third ink layer having a melting point of 65° C. is coated with the composition of 2
100 dots were transferred onto second paper. This was compared with a conventional ink sheet coated on the same heat-resistant support film as shown in Example 1 with a thickness of 8 um of ink having the same composition as shown in Example 1. However, the results shown in Table 1 were obtained. In addition, regarding the evaluation of the printing quality here, the area of the heating element is 1, and the variation in the dot area is expressed as the standard deviation.For the evaluation of the printing density, solid printing is performed and the ○ and D are evaluated. From the measured values, roughly speaking, regarding printing energy, the electrical energy required to produce the highest density with the conventional ink sheet mentioned above is 1
Each is expressed quantitatively by the value when . [Example 2] On the same heat-resistant support film as in Example 1, 60 wt% of paraffin wax and 20 wt% of maleic anhydride copolymer were added.
%, vinyl acetate 5 wt%, EEA 5 wt%, and carbon black 10 wt%, the first ink layer with a melting point of 85 ° C. was coated to a thickness of 2 um, and on top of that, phenoxy was the main component and incyanate was used as a crosslinking agent. Carbon black was dissolved in a mixed solvent of toluene-methyl ethyl ketone-MI BK, and the solid content was 25 wt%.
Solvent coat the added material and dry it? &
After curing for 24 hours at 50℃, the film thickness was 0.2μ.
35 wt% of carnauba wax, 30 wt% of polyethylene, and roughly on this intermediate layer.
A second ink layer having a composition of 20 wt% EA and 15 wt% carbon black and having a melting point of 55° C. was coated to a thickness of 5 μm by a hot melt method to prepare an ink sheet. When this was transferred onto cotton paper in the same manner as in Example 1, the results shown in Table 1 were obtained. [Example 3] 30wt% microcrystalline wax, 25wt% deformed (polar) wax, and 25w polyvinyl alcohol were placed on a heat-resistant support film made of PET with a film thickness of 3um.
t%, EVA 15wt%, carbon black 10wt
The first ink layer having a melting point of 45°C and having a composition of
On top of this, an acrylic emulsion was coated with a dry film thickness of 1 μm to form an intermediate layer with a softening point of 80°C, and on top of this intermediate layer, 20 wt % of paraffin wax and 50 wt % of maleic anhydride copolymer were applied. %
, polyethylene 10wt%, EEA 10w
A second ink layer having a melting point of 70° C. and having a composition of 0 wt % EVAl and 0 wt % EVAl was coated to a thickness of 3 um to form an ink sheet. When this was transferred onto cotton paper in the same manner as in Example 1, the results shown in Table 1 were obtained. (Effects) As described above, according to the present invention, the first and second heat-melting ink layers are laminated above and below the middle n layer, which is made of a low melting point material whose viscosity decreases little with temperature. , during a series of recording and transfer steps of applying heat and peeling off the heat-resistant support film, the intermediate layer becomes able to transfer the melted ink of the first ink layer onto the recording medium while maintaining it in a layered manner, improving the surface smoothness. Even when transferring onto a recording medium with poor quality, the unevenness of the surface will cause a shadow! It is possible to transfer the ink uniformly without causing any damage, and it is possible to form a high-quality image with no variation in the transferred dots and high print density. The thermal energy required for transfer can be greatly reduced. 4. Brief description of the drawings FIG. 1 is a diagram showing the layer structure of an ink sheet constituting an embodiment of the present invention, FIG. 2 (aXb) is an explanatory diagram showing each state of transfer by the ink sheet described above, FIG. 3 is a diagram showing the characteristics of the intermediate layer and the ink layer, and FIG. 4 (aXb) is a diagram showing the state of transfer using a conventional ink sheet. 1... Ink sheet 11... Heat resistant support film 12... First ink layer ] 3... Middle n layer 14
...Second ink layer h...Thermal head S
...Record paper applicant Seiko Epson Co., Ltd. agent Patent attorney Keiji Nishikawa Figure 1 Figure 2 (α (button)

Claims (4)

[Claims] (1) At least a heat-resistant support layer, a first ink layer, an intermediate layer,
A thermal transfer ink medium comprising a second ink layer. (2) The first ink layer has a melting point or softening point of 40°C to 20°C.
A thermoplastic substance having a temperature within the range of 0°C, and a second
The ink layer is a thermoplastic material having a melting point or softening point within the range of 50°C to 150°C, and the intermediate layer is a thermoplastic material having a melting point or softening point of 40°C or higher, or a thermoplastic material having a melting point or softening point of 40°C or higher. The thermal transfer ink medium according to claim 1, wherein the thermal transfer ink medium is a synthetic material. (3) The thermal transfer ink medium according to claim 1, wherein the intermediate layer does not flow when heat is applied. (4) The heat-resistant support layer has a thickness of 1 to 12 μm, the first ink layer has a thickness of 1 to 5 μm, and the intermediate layer has a thickness of 0.1 to 3 μm.
The thermal transfer ink medium according to claim 1, wherein the second ink layer has a thickness of 2 to 10 μm.