JPH02301476A - Thermal transfer recording apparatus - Google Patents

Abstract

PURPOSE:To realize good printing quality on all sorts of papers or media to be transferred by separately providing a recording part for melting solid ink under heating and a transfer part for pressure transfer and constituting a transfer medium of a base material and the heat-meltable ink consisting of fine coated parts and uncoated parts applied to the base material. CONSTITUTION:A recording apparatus is a pressure transfer system wherein the surface of an ink layer is pressed by an elastomer like a rubber body and the ink layer is allowed to follow the surface unevenness of paper by elasticity. The elastomer 2 of a pressure roller is deformed by pressure so as to conform to the surface of the paper. Since an ink film 4 being a transfer medium is extremely thin so that the support thereof is 3-6mum and the ink layer thereof is 1-5mum, the transfer of the ink film 4 to the recessed surface of the paper is possible in almost all cases. When a current is supplied to the heater of a thermal head 3, since ink is formed at every fine regions, the dispersion of heat to the outside of said regions is only generated through the ink film and, therefore, melting and non-melting at every ink fine parts are secured until pressure transfer. Further, since the flocculation force in the cross-sectional direction of ink is not generated at the time of the release of the film, smooth release can be performed and the cutting of printing is improved.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to thermal transfer printers, copying machines, facsimile machines, and other thermal transfer recording devices, and particularly to relatively high-speed line-type thermal transfer recording devices that have low smoothness. The present invention relates to a thermal transfer recording device that can transfer good print quality and images even to plain paper.

[Conventional technology l In recent years, #j1 transcription recording is non-impact and noiseless.

It is used in many fields such as facsimiles, computer terminals, and recorders because it has characteristics such as being maintenance-free, low cost, compact and quantifiable, and colorizable.

This type of thermal transfer recording method uses a thermal head to heat the surface of the recording material, or a current-carrying head to energize and heat a heat-generating resistive layer, thereby melting and transferring the ink onto the recording paper to form prints or images. FIG. 6 shows a general configuration diagram of the vicinity of the recording section of the thermal transfer recording apparatus.

However, when plain paper is used as the transfer paper, the transferability of the single-strand transfer recording method is affected by the unevenness of the surface of the plain paper, the physical properties of the surface, the adhesive strength of the ink layer, the permeability, etc. In the case of paper with large surface irregularities, the thermally molten ink adheres only to the convex portions or the vicinity thereof, resulting in parts of the printed image being chipped off and degrading the print quality.

As a means to solve the above problems, the composition and structure of the ink film are improved, or the tII structure of the head is improved to improve paper contact. Alternatively, various techniques have been proposed, such as increasing the contact pressure between the head and platen, or applying vibration to the head.

For example, regarding ink films, JP-A-60-26
4291, JP-A No. 60-264295, JP-A No. 61-244590, etc., a technology in which a thermally decomposable or thermally expandable foaming agent is contained in the ink layer or release layer. , JP-A-63-67178, JP-A-63-7
As shown in No. 8792 and the like, a technique has been devised in which a thermal transfer recording material is coated with a heat-melting coating material and an image forming element is thermally fused onto a substrate or exposed through a binding material.

Regarding heads, as shown in JP-A No. 58-59865, the glaze shape is raised in two stages to improve paper contact, and as shown in JP-A-61-110569, the glaze is formed on the edge of the substrate. Techniques for arranging heating elements have been devised.

Furthermore, in the printing mechanism, there is a method of setting the head pressure to a specific value or more as in JP-A No. 61-219665, and
-173956 or JP-A-61-164853
No. 61-2075, which aims to reheat the transfer machine and allow the ink to penetrate into the recesses.
As in No. 9, a technique has been proposed in which a vibration oscillator is provided in the head and the transfer performance is improved by the vibration of the vibration oscillator.

There was also a proposal for a pressure transfer method, published in Jitsu Shimbun in 1982.
-77254 and JP-A-62-297178.

[Problems to be Solved by the Invention] However, although there has been improvement in printing quality with regard to the above-mentioned ink film and improvement of the head structure, it has not been so effective even when used in a conventional printing mechanism. This is just a small part of what it brings.

In particular, regarding the printing mechanism, there was a drawback that when the head pressure was increased, the friction between the paper and the ink increased, causing background smearing, which significantly deteriorated the printing quality.

In addition, the transfer machine reheating method is based on the assumption that sufficient ink has been transferred to the paper during transfer, and with paper with low smoothness, it is important that ink does not adhere to the lower side during transfer. There was a problem.

As for the vibration method, there are doubts about its practical application as it causes wrinkles in the ink transport.

Furthermore, regarding the pressure transfer method, it is highly questionable whether the recorded dots can maintain their shape after being heated and recorded on the ink film until they are transferred. because,
It is highly conceivable that the ink area melted during recording will wrinkle and expand due to thermal diffusion, or that the overall amount of heat will decrease due to thermal diffusion and solidify before transfer, making transfer impossible.

Therefore, the present invention solves the above-mentioned printing machine loading problem, particularly by making an unprecedented improvement in the transfer medium in pressure transfer, and making it suitable for all types of paper or transfer media, from low smooth paper to high smooth paper. The purpose is to achieve high print quality.

[Means for Solving the Problems 1] The thermal transfer recording device of the present invention is provided with a recording section that heats and melts solid ink and a transfer section that transfers it under pressure, and a transfer medium is coated on a base material. The hot l8 fusible ink is characterized in that the coated portion thereof has a structure consisting of randomly minute coated portions and uncoated portions.

Furthermore/or, the transfer medium is characterized in that the coated ink portion has supercooling properties.

[For production] -119 is the surface unevenness of paper called rough paper.

The depth of the groove is 20 to 40 μm, and the width of the groove is about 200 am. With conventional ink films, 1
It was impossible to transfer only dots. The relationship is shown in FIG. In the figure, 9' is the paper surface, and the blackened area is the area corresponding to one dot.As is clear from Figure 1, there is a high probability that the ink melted area will not come into contact with the paper, resulting in voids and white spots. Naturally, there are irregularities on the paper in both the main scanning direction and the sub-scanning direction, and no matter how much pressure is applied with a rigid thermal head, the ink melting part cannot be brought into contact with the paper surface.

In contrast, the recording apparatus of the present invention presses the ink surface with an elastic body such as a rubber body, and uses the elasticity of the ink surface.

This is a pressure transfer method that allows the ink layer to follow the unevenness of the paper surface. An explanatory diagram is shown in Fig. 2. In Fig. 2, reference numeral 2 denotes an elastic body of a pressure roller, which is deformed by bending on the surface of the paper by pressure. The ink fill t, which is a transfer medium, has 3 to 6 supports.
Since the ink layer is extremely thin, measuring 1 to 5 μm, rigidity is hardly a problem.

119, the ability of an ink film to follow the concave surface of paper can be expressed by the following formula.

Here, W: film deflection q: pressing pressure d: diameter of paper recess E: film Young's modulus t: film thickness V: Poisson's ratio Applying actual values to this equation, d is 200
~300um< leprosy distribution.

The amount of film deflection can be secured at 3011 or more when the rubber hardness is 60°, and transfer to concave portions is possible in most cases, but transfer may not be possible where d is smaller than 200 μm and groove a exceeds 20L1m. However, in reality, there are only a few places where such defects exist (a single white body of paper is pressed and the convex part sinks, and furthermore, the probability that a single dot exists in that place without touching anything around it is extremely high). Because it is so small, it hardly poses a problem when it comes to actual prints.

Although sufficient contact pressure can be applied to paper with low surface smoothness in this way, reproducibility of the dot diameter can be ensured by devising the transfer medium as described above. FIG. 3 shows an overview of the transfer medium in the present invention, and FIG. 4 shows a cross-sectional view of the ink film and the heat distribution on the film. When the heating element of the thermal head is energized, the ink film is heated. The temperature on the surface (ink side) has a distribution as shown in (A). This becomes region W in the cross section of the film. Since the ink is formed in each minute area, heat dispersion outside this area can only occur through the support film 4.
Until the pressure transfer, melting and non-melting of each minute ink portion 9 is ensured. or.

Since there is no cohesive force in the cross-sectional direction of the ink when the film is peeled off, it can be peeled off smoothly and the so-called sharpness of the print can be reduced.
It becomes extremely good. Furthermore, although the ink temperature naturally changes and decreases over time, this problem can be solved by using supercooled ink.

[Embodiment] FIG. 1 shows a block diagram of a printing mechanism in an embodiment of the present invention. In the figure, 1 is a platen roller, and 2 is a pressure roller. The platen roller is preferably a rigid metal body or one whose surface is coated with a high-hardness rubber elastic body with a thin wall thickness (l"/1 or less). In the present invention, the rollers are made of stainless steel and have a diameter of φ to prevent deformation under high pressure.
A platen roller of 40"/cm was used.

The pressure roller has NBR, CRlBR, S on the metal shaft surface.
In general, the hardness of the rubber should be within the range of 30° to 100°.In particular, the lower the smoothness of the paper, the lower the hardness of the rubber. In the present invention, the roller diameter φlO"/, the rubber wall thickness 21/, and the coating with NBR are designed so that the pressing force is arbitrary.

No. 3 is a recording head, which is a line thermal type head shown in FIG. 6, in which a heating element is provided at the tip that contacts the ink film. Unless it has such a special shape, it is impossible to make the distance between the recording section and the pressure section more than a certain value.In the present invention, the distance between the recording section and the center of the pressure section is
It has a structure that can be changed from 6"/ to 14"/.

FIG. 3 is a general view of the transfer medium in the present invention. 4 is a support for the ink film, and a conventionally known film such as PET, polyamide, polyimide, etc. is used. In the present invention, a PET film with a thickness of 6 um was used. From the original purpose, a thinner film is preferable, and the usable range is 25 μm.
It is about ~12u. The ink layer needs to maintain its molten state or hardened state until pressure transfer.

This 75. Several proposals have been made in the past.

G) #It4 Pigments (C, B) in the mixture of fat and wax
In the present invention, the ink is added with a supercooling agent. 3 It was coated on the support in the manner of tapping arabesque in Figure 4-1. Examples of the supercooling agent include sulfur, acetanilide benztriazole, N-ethyl-P-toluenesulfonamide, dicyclohexyl phthalate, etc., or derivatives thereof.
Use alone or in combination of two or more components. These over-cooled materials and bangu are paraffin wax, microcrystalline wax, carnauba wax, oxidized wax, candelilla wax, montan wax, fischer-robuschwax, a-olefin/maleic anhydride copolymer, and fatty acids. amides, fatty acid esters,
Any organic substance exhibiting thermoplasticity, such as distearyl ketone, polyethylene resin, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer epoxy resin, etc., or a mixture thereof, is mixed by transport.

Add pigments such as C and B to make ink materials. In order to coat this in an arabesque pattern, microgravure coating or
0 In the present invention, ink coating was performed by a solvent coating method 0 In the present invention, the melting point is 72°C, the freezing point is 4
A 5°C ink was produced and used for evaluation.

(Example 1) An ink film as shown below was produced, and print quality was evaluated under various conditions. The head used was a 300 dpi product, and the paper used was representative brands of high-quality paper, plain paper, and rough paper. The ink composition is shown below.

Toluene is used as a reagent, and the total solids concentration of the ink is 5 to 4.
In the present invention, toluene was used as the solvent.

The present invention is not limited thereto (such as methyl ethyl ketone, tetrahydrofuran, acetone, methyl isobutyl ketone, cyclohexanone, butyl acetate, ethyl acetate, ethanol, 5 methanol, carbon tetrachloride, etc.).
A solvent or water alone or in combination can also be used.

The ink produced in Example 1 exhibited supercooling properties, and the coated area in an arabesque-like state as shown in Fig. 3 had a Beck smoothness of 2 to 2.
3 seconds Lanca Coubond paper.

18-30 seconds Xerox 4024 paper, 100-120
The results were compared by printing on special thermal transfer paper. By optimizing the film transport speed and pressure conditions, we were able to obtain print quality on Lancaster bond paper that was equivalent to that on thermal transfer paper.

Although the embodiments have been explained using monochrome black ink, it goes without saying that the invention can be similarly applied to color ink.

Effects of the Invention J As explained above, the thermal transfer recording device has a structure in which the recording section and the pressure transfer section are separated, and the transfer medium is.

The heat-melting ink coated on the base material has a structure consisting of randomly minute coated parts and uncoated parts in the coated part, and/or the ink has supercooling mobility. Even when transferred to low-smooth paper, clear and clean prints can be achieved. Furthermore, it can be applied to color, greatly expanding the possibilities of printout methods using thermal technology.

[Brief explanation of drawings]

FIG. 1 is a basic configuration diagram of a thermal transfer recording apparatus according to the present invention, FIG. 2 is a diagram explaining the principle of pressure transfer according to the present invention, FIG. 3 is an overview diagram of an ink film according to the present invention, and FIG. ), (
b) shows the ink film cross section and temperature distribution diagram, Figure 5 shows the principle of the conventional method, and Figure 6 shows the conventional thermal transfer method.
It is a basic configuration diagram of a hammer device. l...Platen roller 2...Pressure roller 2'...Rubber-like elastic body 3...-Line thermal head 4..., ink film (transfer medium) 4-To ink layer 4-2/to the transferred object Portion 4-3 where the transferred ink has come off, ink 5 transferred to the transferred object... unwinding side film roll 6... winding side film roll 8... film peeling roller and guide roller 9...・Paper (transferred material) Applicant: Seiko Epson Co., Ltd. Agent Patent Attorney Kizobe Suzuki (1 person) Figure 1 Figure 2 Figure 4- Figure 3 Figure 4

Claims (2)

[Claims] (1) A thermal transfer recording device that uses a line thermal head as a recording head and has a recording section that heats and melts solid ink on a transfer medium and a transfer section that presses and transfers the transfer medium to an object to be transferred, which are provided separately. In this, the transfer medium is characterized in that the heat-melting ink coated on the base material has a structure in which the coated area is randomly composed of minute coated areas and uncoated areas. A thermal transfer recording device. (2) The thermal transfer recording device according to claim 1, wherein the transfer medium has a supercooling property in a coated ink portion.