JPS6299179A - Surface-smoothening method for solid ink - Google Patents

Abstract

PURPOSE:To enable the surface of a transferred solid ink to be efficiently smoothened, by a method wherein a smoothening means having a high- temperature part the temperature of which is not lower than the melting point of a solid ink and a low-temperature part the temperature of which is lower than the melting point is brought into contact with the surface of the solid ink, and both of them are moved relative to each other. CONSTITUTION:When a heating element 4c of a smoothening means 4 is operated to generate heat, an ink at the surface of an ink roller 4 making contact with the heating element 4c is softened or melted. At this time, the ink roller 1 and the smoothening means 4 make contact with each other not only at the heating element 4c but also at a glass plate 4b. The glass plate 4b is maintained at a temperature lower than the softening point of the ink, so that the ink roller 1 at the part in contact with the glass plate 4b is not softened. Thus, the smoothening means 4 is prevented from bitting into the ink roller 1. In addition, the softened or melted ink is applied to the surface of the rotating ink roller 1 in a small thickness, and the surface of the ink roller 1 is uniformly smoothened by the surface tension of the molten ink.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application> The present invention relates to a method for smoothing the surface of solid ink used in thermal transfer recording and the like.

<Prior Art> Thermal recording method has been widely used in recent years because the device is small and lightweight and has no noise, as well as being able to record on plain paper.

Conventional general heat-sensitive recording methods use an ink film in which heat-melting ink is thinly coated on a heat-resistant base film, but this is disposable only once, and heating of the ink is also possible using a heat-resistant base film. Because it is carried out through a network, it is not efficient and has drawbacks such as high running costs.

For this reason, recently the ink to be transferred is solidified into a roll,
A method of directly heating the surface of the ink roller has been proposed (Japanese Unexamined Patent Publication No. 126193/1983).

In this method, the surface of a rotating ink roller that has been solidified into a roll is directly heated in an image pattern using a laser beam or the like, and the molten ink is transferred onto a sheet serving as a transfer medium to record an image. Furthermore, as the ink is transferred, minute irregularities occur on the surface of the ink roller after the transfer, but if the next transfer recording is performed with these irregularities remaining, the recording quality will deteriorate due to the occurrence of such irregularities after the transfer. Therefore, a smoothing means is provided which heats and melts the surface of the ink drum after transfer to smooth it.

<Problems to be Solved by the Invention> In the method using the ink roller described above, the diameter of the ink roller decreases as ink is transferred. Therefore, the smoothing means for smoothing the roller surface must be biased toward the ink roller by a spring or the like so that it always comes into contact with the ink roller surface.

However, a problem has arisen in that the smoothing means heated by the bias melts the ink roller and bites deeply into the roller in the radial direction. Even if the ink is not penetrated deeper, the flow of the molten ink is blocked on the rotational upstream side of the ink roller l with respect to the smoothing means 4 as shown in FIG. There was a problem in that it spread in the axial direction of the roller and fell off both ends of the roller.

The present invention aims to solve the above-mentioned conventional problems and provide a method for smoothing the surface of solid ink, which makes it possible to efficiently smooth the surface of solid ink after transfer.

Means for Solving the Problems> The means of the present invention for solving the above-mentioned conventional problems is to provide a solid ink with a smooth surface having a high temperature area above the softening temperature and a low temperature area below the softening temperature of the ink. The method is characterized in that the surface of the solid ink is smoothed by bringing the means into contact with each other and moving the two relatively.

According to the above means, the ink surface that comes into contact with the high-temperature part of the smoothing means is softened and melted and smoothed, but the ink surface that comes into contact with the low-temperature part is not softened, so that the smoothing means digs into the ink in the thickness direction. At the same time, the ink droplets also disappear.

<Example> Next, an example in which the above means is applied to a thermal transfer recording apparatus will be described.

FIG. 1 is an explanatory diagram of a thermal transfer recording apparatus for realizing this embodiment. To explain the outline, 1 is an ink roller made by solidifying ink having supercooling characteristics into a roll shape, and is formed into a cylindrical shape having approximately the same width and length as the recording sheet. It is configured to come into pressure contact with the rotating pressure roller 2 and rotate in the direction of the arrow as the pressure roller 2 rotates.

Further, with reference to the pressure contact portion between the ink roller 1 and the pressure roller 2, heat is generated on the upstream side in the rotational direction of the ink roller 1 according to image information, and the ink roller 1 is recorded to melt or soften in an image pattern. A head 3 and a smoothing means 4 for smoothing the surface of the ink roller 1 on the downstream side are arranged so as to contact the surface of the ink roller 1, respectively.

Further, in synchronization with the rotation of the ink roller 1, the recording sheets 6 stored in the supply cassette 5 are separated and conveyed one by one by a supply roller 7 and a pair of timing rollers 8, and are separated and conveyed one by one between the ink roller 1 and the pressure roller 2. It is configured to be discharged through the discharge tray 9.

Therefore, the surface of the ink roller l rotating in the direction indicated by the arrow is melted or softened in an image pattern by the recording head 3, reaches the pressure contact part with the pressure roller 2 in that state, and is conveyed at the pressure contact part. The molten or softened ink is transferred to the recording sheet 6 that comes, an image is recorded, and the recording sheet 6 is discharged to the discharge tray 9.

On the other hand, minute irregularities remain on the surface of the ink roller after the ink has been transferred, but these irregularities are uniformly smoothed by being heated and melted by the smoothing means 4.

The diameter of the ink roller 1 gradually decreases as ink is consumed, but even if the diameter changes, the ink roller 1 is urged toward the pressure roller 2 by the spring 1a so as to come into pressure contact with the pressure roller 2. The recording head 3 and the smoothing means 4 are supported by springs 3a and 4a, respectively, so that the recording head 3 and the smoothing means 4 are always in contact with the surface of the ink roller 1.
is biased in the radial direction.

Here, the ink roller 1 and the smoothing means for smoothing the surface of the ink roller 1 in the transfer recording will be described in more detail.

First, the ink roller 1 will be explained. As mentioned above, since there is a time lag between the ink of the ink roller 1 being heated by the recording head 3 and being transferred to the recording sheet 6, it is made of ink that has supercooling characteristics. Ink that has this supercooling property is a melted or softened state that can be transferred to the recording sheet 6 even at a temperature below the ink's original melting point or softening point when it is heated to melt or soften and then cooled. An ink that maintains its state for a certain period of time, and is a coloring agent consisting of a thermofusible binder with supercooling properties and a dye or pigment commonly used in printing or other recording methods, such as carbon black, either singly or in a mixture of two or more. It is made by dispersing the

Here, as an example of the thermofusible binder having supercooling properties, N-cyclohexyl-p-
) Plasticizers such as luenesulfonamide, N-ethyl-p-toluenesulfonamide, dicyclohexyl phthalate, benzotriazole, acetalinide, etc., or derivatives thereof, alone or in combination of two or more, are used for conventional thermal transfer. Conventional heat-melting binders made of thermoplastic resins such as polyamide resins, polyacrylic resins, polyvinyl acetate resins, or copolymers of these, various natural or synthetic waxes, etc. used in sex inks. The ink roller 1 is obtained by solidifying this into a roll shape in a mold etc.
can be obtained.

In order to obtain the supercooled thermofusible binder used in this example, for example, 20 to 90 parts by weight of the supercooled substance may be mixed into 10 to 90 parts of the conventional thermofusible binder; An oil agent or the like may be added to the supercooled thermofusible binder to adjust its supercooling characteristics, or an elastomer or the like may be added to adjust the melt viscosity, adhesive strength, etc.

The ink having supercooling characteristics has a melting point or softening point of preferably about 40 to 200°C, more preferably about 50 to 180°C, and is melted or softened by being heated above the melting point or softening point. After that, the time until solidification starts when left at room temperature is preferably 0.
．． About 1 second to 100 seconds, more preferably 0.1 seconds to 10 seconds
It is set to about seconds.

Next, smoothing means 4 smooths the surface of the ink roller l.
I will explain about it.

As shown in FIG. 2, the smoothing means 4 uses a flat glass plate 4b as a smooth base, and a heating element 4C is formed at a predetermined position on the glass plate 4b. is energized. Said heating element 4C
The width is about 2 by spackling titanium on the glass plate 4b.
00 μm, thickness of approximately 0.5 μm, and the length is the same as the length in the axial direction of the ink roller 1, and is formed by photolithography, and lead wires are connected to both ends of the titanium wire. The titanium wire is configured to generate heat by passing a current through it.

Although the amount of heat generated by the heating element 4C varies depending on the softening temperature and viscosity of the ink to be smoothed, it is adjusted to generate heat at a high temperature higher than the temperature that softens the ink of the ink roller I. Therefore, when the heating element 4C generates heat, the temperature of the heating element portion becomes higher than the softening point of the ink, but the glass plate 4
b has low thermal conductivity, so it is difficult to reach a high temperature, and as a result, in the entire smoothing means 4, there is a part (the part of the heating element 4C) that is higher than the softening point of the ink, and a part (the part of the glass plate) that is lower than the softening point of the ink. 4b) will exist.

Furthermore, when the smoothing means 4 comes into contact with the surface of the ink roller 1, it is arranged so that the heating element 4C is located slightly downstream in the direction of rotation of the ink roller 1 from the center C of the contact area between the two, as shown in FIG. are in contact.

Next, the case where the surface of the ink roller 1 is smoothed by the smoothing means 4 will be explained.

First, when the heating element 4C of the smoothing means 4 generates heat while rotating the ink roller 1 at a circumferential speed of about 50 mm/sec, the ink on the roller surface that is in contact with the heating element 4C is heated above its softening point and softens. At this time, the ink roller 1 and the smoothing means 4 come into contact not only with the heating element 4C but also with the glass plate 4b due to changes in the elasticity of the ink roller 1. Since this glass plate 4b has a low temperature below the softening point of the ink as described above, the ink roller 1 does not soften at the contact portion of the glass plate 4b. This prevents the roller from biting into the roller 1 even if it is biased in the direction.

Furthermore, at the contact portion between the ink roller 1 and the smoothing means 4,
Since the heating element 4c is located on the downstream side in the rotational direction of the ink roller l, the smoothing means 4 is located on the rotational upstream side of the ink roller 1.
It comes into contact with the glass plate 4b which is the low temperature part of the glass plate 4b. Therefore, the ink does not melt on the upstream side, and as a result, the situation in which melted ink is blocked by the smoothing means 4 and drips as in the conventional case does not occur.

Furthermore, as shown in FIG. 2, the ink softened and melted by the heating element 4C accumulates downstream of the contact area between the ink roller 1 and the heating element 4C, and is thinly applied to the surface of the rotating ink roller 1. , and the surface of the ink roller l is uniformly smoothed by the surface tension of the molten ink.

In addition, when the heating element 4C of the smoothing means 4 has a minute width, the top of the ink pool melted by the heating element 4C cools and solidifies, and the solidified ink is applied to the surface of the rotating ink roller 1. It may adhere intermittently. Such a problem occurs when the molten ink has a relatively low viscosity, such as an ink that uses wax or the like as a heat-melting binder. Also, if the heating element 4C is positioned downstream in the rotational direction of the ink roller 1 from the contact center C between the ink roller 1 and the smooth member 4 as shown in the above embodiment, the heating element 4C can reach the top of the molten ink reservoir 1b. Since it is heated by 4C, it will not solidify, and therefore the above-mentioned disadvantages will not occur. Here, the optimal value for the amount by which the heating element 4c is shifted downstream from the contact center C varies depending on the viscosity of the molten ink, but it is preferably set to about 30 μs1 to 2 times. Note that the above value is not absolute. ,
Even if the heating element 4c is slightly removed from the contact area with the ink roller 1, if the amount is small, no problem will actually occur because the ink will be softened by the heat conducted to the glass plate near the heating element 4c. .

The above configuration has been described for the case where the viscosity of the molten ink is low, but conversely, when the viscosity of the molten ink is relatively high, the ink melted by the heating element 4c does not accumulate and adheres uniformly to the rotating ink roller 1. Therefore, there is no need to dispose the heating element 4c on the downstream side as described above, and the ink roller l
Even if the heating element 4c is placed at the contact center C of the smoothing means 4, no problem will occur.

As mentioned above, when smoothing the surface of solid ink,
Various conventional problems can be solved by abutting and smoothing a smoothing means having a portion with a temperature higher than the softening temperature of the ink and a portion with a lower temperature.

In the above-mentioned embodiment, the heating element 4C was constructed by passing a current through titanium, but the heating element 4C may be of any type as long as it reaches a high temperature higher than the softening temperature of the ink. Other examples include metals such as nickel-chromium alloys, tungsten, and metal oxides such as tin oxide.

In addition, when forming such a heating element on a smooth substrate, several liters of O
If it is about μm, no problem will occur even if it protrudes from the smooth substrate.

Although the glass plate 4b was used as the smooth substrate in the above embodiment, it may be made of any material that is heat resistant and has a relatively low thermal conductivity. Heat-resistant resins may also be used.

Next, another embodiment of the smoothing means will be described.

In the above-mentioned embodiment, the flat glass plate 4b was used as the smooth base, but another embodiment may be used as shown in FIG. 3.The smoothing means 4 shown in FIG. A columnar glass rod 4d is used, and a large number of minute electric heating elements 4e are arranged on the longitudinal surface of the glass rod 4d, so that the smoothing means 4 can be rotated about the center 0 of the glass rod 4d as a rotation axis. It is composed of

With the above configuration, in the case of ink having a relatively low melt viscosity, the high temperature part of the smooth member 4 can be easily and freely shifted by simply rotating the smooth part 4 and adjusting the rotation angle θ. It can be done.

Further, with the above-described configuration, since the contact portion between the ink roller 1 and the smooth member 4 has a convex curved shape, the molten ink pool 1b between the ink roller 1 and the glass rod 4d becomes small, and the heat generating element 4e is Since the distance to the top of the molten ink reservoir 1b is shortened, there is no need to shift the high temperature part downstream so much, and by setting the rotation angle θ to about 1 to 10 degrees, it is possible to use low-viscosity molten ink. Even if there is a problem, stable smoothing can be achieved.

In the above-mentioned embodiments, the high-temperature portion has a very small width, but as another example, the high-temperature portion of the smoothing means 4 may have a wide width as shown in FIG. 4. The smoothing means 4 shown in FIG. 1 has a heat-generating portion 4r that extends widely from the center of contact between the ink roller 1 and the smoothing means 4 in the rotational downstream direction of the ink roller 1.

With the above structure, in order to reliably heat up to the top of the molten ink pool lb accumulated between the ink roller 1 and the smoothing means 4, the heat generating portion 4r as in the above embodiment is heated.
It is possible to prevent the molten ink from solidifying without shifting the ink roller 1 in the rotational downstream direction.

In addition, in the embodiment shown in FIGS. 1 to 4, an example of an ink roll in which solid ink is formed in a roll shape is shown, but in the present invention, the solid ink is limited to a roll shape. It is obvious that the present invention can also be applied to other types of belts, such as those in which ink is adhered to the surface of a rotating belt.

<Effects of the Invention> As described above, in smoothing the surface of solid ink, the present invention brings into contact a smoothing means having a high temperature part above the softening temperature of the ink and a low temperature part below the temperature, and makes the two relative to each other. Since this is done by moving the solid ink to a high temperature area, the unevenness on the surface of the solid ink can be softened and smoothed by the high temperature part, and even if the ink is softened, the low temperature part of the smoothing means does not touch the ink surface. By contacting the smoothing means, it is possible to prevent the smoothing means from digging into the ink in the thickness direction, and it is also possible to prevent the softened and melted ink from dripping. Furthermore, if the high-temperature portion of the smoothing means is brought into contact with the downstream side in the direction of movement of the ink, the surface of the ink can be reliably and efficiently smoothed even if the high-temperature portion is minute.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram of a thermal transfer recording apparatus for explaining one embodiment of the present invention, FIG. 2 is an explanatory diagram of the relationship between an ink roller and a smoothing means, and FIGS. 3 and 4 are other embodiments. An explanatory diagram of
FIG. 5 is an explanatory diagram of the prior art. 1 is an ink roller, 2 is a pressure roller, 3 is a recording head,
4 is a smoothing means, 4a is a spring, 4b is a glass plate, 4
C is a heating element, 4d is a glass rod, 4e is a heating element, 4f is a heating section, and 6 is a recording sheet.

Claims (4)

[Claims] (1) A method for producing a solid ink characterized in that a smoothing means having a high temperature part above the softening temperature of the ink and a low temperature part below the softening temperature is brought into contact with the surface of the solid ink, and both are moved relative to each other. Surface smoothing method. (2) The method for smoothing the surface of solid ink according to claim 1, characterized in that the vicinity of the boundary between the high-temperature part and the low-temperature part of the smoothing means is brought into contact with the surface of the solid ink. (3) The method for smoothing the surface of solid ink according to claim 1 or 2, wherein the upstream side of the solid ink in the moving direction contacts a low-temperature portion of the smoothing means. (4) The surface of the solid ink according to any one of claims 1 to 3 is smoothed by heating a portion slightly downstream of the center of the contact portion between the solid ink and the smoothing means. Method.