JPS62297178A - Thermographic recording method - Google Patents

Abstract

PURPOSE:To obtain a large number of clear copies with excellent printing quality, by supplying energy to a thermally transferrable ink layer comprising a supercoolable polyamide resin to melt or soften a thermally transferrable ink, transferring the ink to a recording medium under pressure, and repeating the pressure transferring step. CONSTITUTION:A thermally transferrable ink layer 2 comprising a supercoolable polyamide resin is provided on a base 1, and is supplied with energy imagewise to selectively melt or soften a thermally transferrable ink. The melted or softened ink is transferred to a recording medium 6 under pressure, and the pressure transferring step is repeated. The ink retains stickiness in the state of a relatively high melt viscosity based on the action of the polyamide resin as a binder, and the change of the melt viscosity after application of the energy is extremely slow. Accordingly, the ink can be transferred to the recording medium 6 in a substantially fixed amount at a time, and a copied image free of voids or blur, being clear and having excellent printing quality can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION 3. Detailed Description of the Invention The present invention relates to a thermal copy recording method capable of obtaining a clear copy recording image with excellent print quality.

Thermal transfer recording method, which is one of the deployment methods widely used for information processing systems, generally includes a thermal transfer layer formed by dispersing a colorant in a heat-melting binder on a sheet-like support. Using the provided heat-sensitive transfer sheet, the heat-transfer layer of the heat-sensitive transfer sheet is opposed to the recording medium, and heat is supplied from the support side of the heat-sensitive transfer sheet using a thermal head or the like,
By transferring a molten thermal transfer layer to a recording medium, a transferred recorded image is formed according to a heat supply pattern.

This thermal transfer recording method has various excellent features such as the device used is compact and noiseless, but in order to obtain multiple similar recorded images, it is necessary to transfer the thermal transfer sheet to the thermal transfer sheet using a thermal head etc. There is no choice but to adopt complicated and cost-disadvantaged methods, such as repeating the same patterned heat application multiple times or copying the recorded image obtained by one thermal transfer using other copying equipment. I didn't get it.

Separately, a heated print head supplies patterned heat to a supercooled layer of thermal transfer ink to impart selective tackiness, and the ink maintains its tackiness. During this time, a thermal printing method was proposed in which thermal transfer ink was transferred onto multiple sheets of copy paper (Japanese Patent Publication No. 4).
6-15479).

However, in this thermal printing method, plasticizer (p
-) luenesulfonic acid amide derivatives, etc.) to impart supercooling properties to the thermal transfer ink, the thermal transfer ink becomes a liquid with extremely low melt viscosity when the tackiness is maintained. However, it had a tendency to solidify immediately due to some slight external stimulus, becoming a hard and brittle solid state. Therefore, when this thermal printing method is used, it is difficult to maintain uniformity of print quality in the obtained copies, and a recorded image with bleeding is likely to be formed immediately after patterned heat is applied. Recorded images obtained after a relatively long time has elapsed from the application of heat have disadvantages in that print defects and a decrease in print density are unavoidable.

The main object of the present invention is to provide a thermal copy recording method that eliminates the drawbacks of the conventional recording methods described above and can obtain a large number of clear copies with excellent print quality.

As a result of research, the present inventor has found that by incorporating a specific polyamide resin with supercooling properties into thermal transfer ink,
Providing supercooling properties to the ink makes it possible to perform thermal copy recording using the thermal transfer ink that maintains a relatively high melt viscosity, and is extremely effective in achieving the above objective. I discovered that.

The thermal copying recording method of the present invention is based on such knowledge, and more specifically, the thermal copying recording method of the present invention is based on the above-mentioned knowledge. A step of selectively melting or softening the thermal transfer ink layer by supplying patterned energy to the thermal transfer ink layer, and applying the melted or softened ink to a recording medium facing the thermal transfer ink layer of the thermal transfer material. The method is characterized in that the pressure transfer step is performed a plurality of times.

In the thermal copying recording method of the present invention, the thermal transfer ink to which patterned energy is supplied maintains selective tackiness in a relatively high melt viscosity state based on the action of the polyamide resin as a binder, and moreover, The change in melt viscosity of the thermal transfer ink after application is significantly slower than that of conventional supercooling inks using plasticizers.

Therefore, by repeatedly pressing a recording medium against a thermal transfer ink sheet that has been given selective tackiness, it is possible to transfer a substantially constant amount of the ink onto the recording medium, thereby eliminating the possibility of missing prints. It is possible to obtain a copy recorded image that is free from bleeding, has clear print quality, and has high print quality.

Furthermore, in the copy recording method of the present invention, even when patterned energy is applied to a thermal transfer material in the form of a dot-like pattern, the characteristics of the thermal transferable ink described above are utilized to produce thermal transfer with a nearly uniform thickness. The ink layer can be transferred repeatedly to the recording medium.

Hereinafter, the present invention will be described in further detail with reference to the drawings as necessary. In the following descriptions, "%" is used to express quantitative ratio.
"and r part" are based on weight unless otherwise specified.

FIG. 1 is a schematic cross-sectional view in the thickness direction of a thermal transfer material, showing an example of an apparatus system for carrying out a typical embodiment of the thermal copy recording method of the present invention.

Referring to FIG. 1, a thermal transfer material 3 consisting of a supercooled thermal transferable ink layer 2 formed on a sheet (used to include a film) support l is shown in the direction of the arrow in the figure. be transferred to. When dot-shaped thermal energy corresponding to a desired image pattern is supplied to this thermal transfer material 3 from the support l side by a thermal heater 4, the thermal transferable ink constituting the ink layer 2 is Depending on the heating pattern, the ink 21 is thermally melted or thermally softened to become sticky, and has transferability to a recording medium. Since this thermal transfer ink 21 has supercooling properties,
Even after the heating by the thermal head 4 is completed, the thermal transfer material 3 is further sent in the direction indicated by the arrow while being maintained in the thermally melted or thermally softened state.

Next, the thermal transfer material 3 is normally transported in the direction of arrow B so that the supercooled thermal transferable ink layer 2 contacts the recording medium at a transfer position where the pressure rollers 5a and 5b face each other. It is superimposed on the recording medium 6 made of paper or the like, but at this time, pressure is applied between the pressure roller 5a and the pressure roller 5b, and the supercooled thermal transferable ink layer 2 is melted according to the above-mentioned heating pattern. A portion of the ink 21 that remains in a softened state is transferred to the recording medium 6 and forms a transferred recorded image 2.
form 2.

During this transfer, based on the characteristics of the polyamide resin contained in the ink 2, the thermal transfer ink 21 in a sticky state has a relatively high melt viscosity, and the surface of this ink 21 (the surface facing the recording medium) has a relatively high melt viscosity. The melt viscosity is almost uniform along the line. Therefore, by pressure-transferring (part of) this ink 21 onto the recording medium 6, a clear transferred recorded image 22 made of a thin film of thermally transferable ink having a nearly uniform thickness is formed.

Even after the transfer recorded image 22 is formed as described above, the ink 21 containing polyamide resin shows a slow change in melt viscosity and maintains good adhesiveness for a certain period of time, so that the thermal transfer material 3 is wound around the pressure roller 5a, and the roller 5a is rotated in the direction of arrow C, so that the ink 21 is
Further, by bringing the recording medium 6 into contact with the required number of recording media 6 supplied from the recording medium supply means 7, a large number of clear transferred recorded images can be easily obtained.

At this time, based on the properties of the polyamide resin described above, the transferred recorded image obtained as a copy is also formed as a transferred recorded image having almost the same printing quality as the original recorded image 22.

Next, the configuration of each part shown in the drawings will be explained.

As the support l, conventionally known films and papers can be used as they are as long as they have the necessary strength, heat resistance, and flexibility, such as polyester, polyamide, polyimide, polycarbonate, tri-7cetyl cellulose, etc. Plastic films, cellophane paper, capacitor paper, parchment paper, etc. can be suitably used. The thickness of the support is preferably about 2 to 151 Lm, for example.

In addition, the heat resistance of the support is improved by providing a heat-resistant protective layer made of silicone resin, fluororesin, polyimide resin, epoxy resin, phenol resin, melamine resin, nitrocellulose, etc. on the surface of the support that comes into contact with the thermal head. can.

Alternatively, support materials that could not be used conventionally can be used. Moreover, the support body 1 can be multi-layered as necessary for reinforcement.

Thermal transfer ink that forms the ink layer 2 on such a support 1 is made by dispersing a colorant in a heat-melting binder containing a supercooling polyamide resin as an essential component.
This is not intended to exclude the dissolved state).

Here, a polyamide resin having supercooling property refers to a polyamide resin that maintains the above-mentioned molten state for a certain period of time even at a temperature below its original melting point when it is once heated above its melting point and then cooled. In addition, for binder components such as polyamide resins that do not have a fixed melting point, thermal transfer inks, etc., the above-mentioned "melting point" is replaced by "softening point by ring and ball method," and "melting" is replaced by "softening." used.

The polyamide resin used in the present invention is a compound represented by the following general formula (I), (■) or (m).

HO I COR” C0NHRI NH,llH...
・(I)R” NH (COR'C0NHR' NH
) n COR'C0NHR"...(II)R" NHCOR2C0NHR4NHCOR2C0N
HR5-NHCOR2C0NHR” ・(m
) In the above general formula (I), R1 is 01 to C3
hydrocarbon groups, especially -CH2-5-(CH2)2-1
Straight chain aliphatic hydrocarbon groups such as (CH2)i- group are preferred.

On the other hand, as the above R2, -CH2-1-(CH2)2
A linear aliphatic hydrocarbon group such as a -1 (CH2)3- group or a dimer acid residue is preferably used.

Here, the dimer acid is represented by the following structural formula.

(CH2)t -COOH (in dimer acids, this structural formula and the position of the side chain,
Alternatively, various isomers with different double bond positions are present. ) Furthermore, in general formula (I), m (degree of polymerization) is 3 to 3.
0. Furthermore, the degree of polymerization is preferably 3 to 20. If the degree of polymerization is less than 3, the polyamide becomes sticky at a relatively low temperature.
The storage stability of the thermal transferable ink layer becomes insufficient. On the other hand, if the degree of polymerization exceeds 30, the melting point or softening point of the polyamide becomes too high, and a large amount of energy is required to transfer the thermally transferable ink layer.

In addition, in the general formula (II) to m), R2
is the same as in general formula (I) (dimer acid residue is particularly preferred), and R3 is a hydrocarbon group, saturated aliphatic,
Unsaturated aliphatic groups, aromatic groups, or those having an aromatic group in the carbon chain can be considered, but saturated aliphatic groups are particularly preferred. R3 has 1 to 30 carbon atoms, but especially lO A range of 20 to 20 is preferable.

H4 and Hll are divalent hydrocarbon groups, preferably having one bond each on different carbons, but may have two bonds on one carbon.

R4 and R1+ are saturated aliphatic, unsaturated aliphatic,
Possible examples include phenylene groups or those with an aromatic ring in the carbon chain, but among these, saturated aliphatic groups,
and a phenylene group, and R4 and Rs have 1 to 12 carbon atoms, particularly preferably 5 to 10 carbon atoms.

In the general formula (II), as n increases, the supercooling time of the polyamide resin (once heated above the melting point or softening point to melt or soften, and then left at room temperature until solidification starts) The period between poems (the same applies hereafter) becomes longer.

The polyamide resin of the general formula CI) used in the present invention is formed by polycondensation of a diamine and a dicarboxylic acid according to a conventional method.

HO□C-R2-C0□H + H,N -R1-NH2 11 → HO(COR2CONHR' NH) m
H In the above reaction, polyamide resins having various molecular weights can be obtained by capping the terminal 7-mino group (or carboxyl group) of the product using a monocarboxylic acid (or monoamine).

On the other hand, the polyamide resins of general formulas (II) to m) are synthesized by the reaction of the following general formula.

HO2CR'' CO2H In the above reaction, polyamide resins having various degrees of polymerization can be obtained by adjusting the mixing ratio of the raw materials, the reaction conditions, etc.

Examples of the diamine (H2NR' NH2 or H2NR' NH2) used in the above reaction include methylene diamine, ethylene diamine,
Aliphatic diamines such as propanediamine and phenylenediamine may be used in combination of two or more types, if necessary.

The monoamine (R” N H
Examples of 2) include methylamine, ethylamyl, propylamine, stearylamine, tetradecylamine, alinine, P-methylalinine, P-ethylamin, and the like.

On the other hand, dicarbonate fi (
As HOOC-R2-COOH), an aliphatic dicarboxylic acid or a so-called polymerized fatty acid (containing the dimer acid) is preferably used.

Specifically, such aliphatic dicarboxylic acids include:
Malonic acid, succinic acid, glutaric acid, etc.
A combination of two or more species is preferably used.

In addition, the polymerized fatty acid itself is a known substance, and monobasic fatty acids including polyunsaturated fatty acids (particularly 01...
C24 carbon number) or its ester is heated at high temperature or with a catalyst such as di-t-butyl peroxide to polymerize and isomerize, usually.
It is obtained as a mixture of various fatty acids.

Many of the currently commercially available monopolymerized fatty acids are based on unsaturated fatty acids having 18 carbon atoms, and their typical compositions are as follows.

This polymerized fatty acid is used as a dicarboxylic acid constituting the polyamide resin in the present invention in combination with other dicarboxylic acids, if necessary.

The polyamide resin used in the present invention is composed of the above-mentioned diamine (or monoamine) and dicarboxylic acid, but also contains other third components (e.g., polyvalent amine, polyvalent carboxylic acid, crosslinking agent, etc.). You may do so.

The polyamide resin used in the present invention is synthesized by mixing one or more of the above-mentioned diamines, dicarboxylic acids, and monoamines, heating them, and condensing them.

The supercooled polyamide resin obtained as described above is
Its melting point or softening point is preferably set at about 60 to 200°C, more preferably about 70 to 180°C.

Further, the supercooling property of the polyamide resin can be adjusted as appropriate by changing the type 1 composition of the diamine, dicarboxylic acid, etc., but once it is heated above the melting point or softening point, it does not melt. After softening, the time until solidification starts when left at room temperature (hereinafter referred to as "supercooling time") is preferably 1 minute to too many minutes, and more preferably 30 minutes to 100 minutes.

In the heat-melting binder used in the present invention, the above-mentioned polyamide resins may be used in combination of two or more types as necessary.
If necessary, other binder components or additives may be added to adjust melt viscosity, adhesive strength, and supercooling properties.

Examples of such binder components include 1, for example, polyacrylic resins used in conventional thermal transfer inks;
Thermoplastic resins such as polyvinyl acetate resins or copolymers thereof (preferably those with a softening point of 40 to 23 by the ring and ball method)
0°C, more preferably 50 to 200°C), various natural or synthetic waxes, etc. can be used.

In addition, examples of the above-mentioned additives include elastomers,
Non-volatile liquids such as semi-solid to solid fats and oils, animal and vegetable oils, mineral oils, and esters may be used within the scope of the present invention.

The heat-melting binder contains the above-mentioned polyamide as an essential component in an amount of 40% or more, especially 60 to 60%, based on the entire binder.
It is preferable to contain 90%.

As the colorant that constitutes the thermal transfer ink together with the heat-melting binder, all dyes and pigments commonly used in printing or other recording methods such as carbon black can be used, and these can be used alone or in combination of two or more. However, it is preferably contained in an amount of, for example, about 1 to 40% based on the thermal transfer ink.

As mentioned above, the melting point or softening point of the thermal transfer ink consisting of a hot-melt binder and a colorant is 40 to 20
The temperature is preferably 0°C, more preferably 50 to 180°C, and the supercooling time of the ink is preferably about 1 second to 100 minutes, more preferably about 100 seconds to 30 minutes.

If the melting point or softening point of the thermal transfer ink is lower than 40°C, the storage stability of the thermal transfer material 3 will deteriorate and the non-printing area of the recording medium will be stained;
If it is higher, a large amount of thermal energy will be required to melt or soften the ink.

Furthermore, if the supercooling time is shorter than 1 second, it will be difficult to obtain multiple copies, while if the supercooling time is longer than 100 minutes, the recorded image immediately after being transferred to the recording medium may lack stability. Become.

Furthermore, from the point of view of forming a plurality of clear copied recorded images with good reproducibility, the melt viscosity of the thermal transfer ink is 10 to 10' cP at 140°C, and 10' to 10' cP at 140°C.
is preferred.

To obtain the thermal transfer material 3 used in the present invention, 1. For example, a heat-melting binder containing a polyamide resin and a coloring agent (additives if necessary) are melt-kneaded using a dispersion device such as a tritor. The thermal transfer ink layer 2 may be formed by obtaining a thermal transfer ink and coating it on the support 1 with a wire bar or the like.

The thickness of this thermal transferable ink layer 2 has a great effect on the number of copies, and the thicker the ink layer, the greater the number of copies that can be made.
The number of copies that can be made in 1L is about 1 to 30), and even 10 to 5
It is preferable to set it to 0 gm (the number of copies that can be made is about 4 to 15).

The supercooling polyamide resin used in the present invention has excellent flexibility at room temperature (or lower temperatures), so it may not contain crystalline supercooling plasticizers (p-)luenesulfonamide derivatives, etc.). The thickness of the thermal transfer ink layer can be increased compared to the conventional thermal transfer ink used.

The thermal head 4 is a member that supplies heat to the above-mentioned thermal transfer material 3 according to a desired image pattern.

In this heat application by the heating pad 4, the heat-sensitive transfer material 3
The applied pressure may be less than 2 Kg/cm" as long as the thermal head is in sufficient contact to apply heat in the desired pattern,
Furthermore, the width of the applied pulse is suitably set to 0.5 to 5 rasec.

As the rollers 5a and 5b, either an elastic roller whose surface is made of various rubbers, resins, etc., or a rigid roller whose surface is made of metal, ceramics, etc. can be used.

The pressure applied to the thermal transfer material 3 and the recording medium 6 by these rollers 5a and 5b is a linear pressure of 0.1 to 10
Kg/cm2, more preferably 0.5 to 5 Kg/as.

The recording medium 6 may include, but is not particularly limited to, ordinary paper used for recording and printing, special paper treated with coatings, plastic films, etc. Recording media with poor surface smoothness may also be used. The above rollers 5a, 5b
A good recorded image can be obtained by controlling the applied pressure and adjusting the amount of transfer ink.

In the above description, referring to FIG. 1, the thermal transfer ink layer 2 is transferred from the thermal head 4 through the support 1 of the thermal transfer material 3.
Although an embodiment of the present invention has been described in which heat is applied in a pattern to the ink layer 2, the heating pad 4 is placed to face the ink layer 2 side of the thermal transfer material 3 (not shown), and the pattern is directly applied to the ink layer 2. By supplying patterned heat directly to the thermal transferable ink layer 2 in this way, it is possible to effectively utilize thermal energy.

Apart from this, as a means for applying patterned energy to the thermal transfer material 3, for example, a non-contact means such as a laser beam, or a needle-like or multi-stylus-like recording electrode (Japanese Patent Application Laid-Open No. 58-220795 Publication, JP-A-58
It is easy to understand that the copying and recording method of the present invention can be carried out in the same manner even when using a method such as Japanese Patent Publication No. 12790.

Furthermore, as shown in FIG. 2, which is a schematic side view in the thickness direction of the thermal transfer material, it is also possible to supply energy in a pattern to the thermal transfer material 3 using radiation light such as infrared rays.

Referring to FIG. 2, a document 8 having a desired image portion 8a is placed on the support 1 side of the thermal transfer material 3, and a recording medium 6 is placed on the ink layer 2 side of the thermal transfer material 3.

When the thermal transfer material 3 and the original 8 are irradiated with radiant light 9 made of infrared rays or the like from the side of the original 8, the image area 8a absorbs the energy of the radiant light and generates heat, so the thermal transfer is carried out via the support 1. A patterned energy is supplied to the ink layer 2, and a portion 21 of the ink layer 2 is selectively melted or softened.

The thermal transfer material 3 supplied with patterned energy in this way and the recording medium 6 facing it are held between a pressure roller (not shown) or the like in the same manner as in the embodiment shown in FIG. A transferred recorded image is formed on the recording medium 6 by applying a pressing force to the recording medium 6 .

Furthermore, as in the embodiment shown in FIG. 1, by repeating the steps of winding the thermal transfer material 3 around a roller and pressing the thermal transfer material 3 against the recording medium 6, a desired number of copies can be obtained.

When radiant light is used as a means for supplying patterned energy as shown in Fig. 2, a relatively wide area of the thermal transferable ink layer 2 can be melted or softened by applying energy twice, increasing the recording speed. There are advantages.

From JL! l! IL Exhibition As described above, according to the present invention, a thermal transferable ink layer containing a supercooling polyamide resin provided on a support has a
A thermal copy recording method is provided in which a plurality of copies are obtained by melting or softening the ink layer by supplying patterned energy and repeatedly pressing the ink layer against a recording medium.

According to the thermal copy recording method of the present invention, by utilizing the characteristics of polyamide resin having supercooling properties, it is possible to obtain a large number of copies with clear and excellent print quality using a compact device.

Furthermore, in the present invention, since the supercooled ink transferred to the recording paper medium maintains a fluid state for a predetermined period of time, it easily permeates into the recording medium such as plain paper, and after the ink solidifies, it cannot be recorded. Good fixing properties to the medium can be obtained.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

real jl example A polyamide resin was synthesized using the following recipe.

(Numbers are equivalent ratios) As the polymerized fatty acid, Versadime 216 (trade name: Henkel Hakusuisha, C1e monobasic acid approximately 7%).

C% dibasic acid 75%, CF4 tribasic acid 18%)
was used.

The synthesis method was as follows. That is, the above ingredients were placed in a four-bottle round bottom flask equipped with a thermometer, mechanical stirrer, dehydration tube, and nitrogen blowing tube, and heated at 220°C for 5 hours while flowing nitrogen.
℃ and then reduced pressure to 100 mm Hg.
A polyamide resin was obtained by reacting for 1.5 hours.

(Parts by weight) Carbon black (manufactured by Mitsubishi Chemical Industries, Ltd.) 2 parts Above polyamide resin 18 parts Toluene
40 parts Isopropyl alcohol 40 parts Referring to FIG.
A heat-sensitive transfer material 3 was prepared by coating a polyethylene terephthalate film 1 with a thickness of JLm using a wire bar to form a layer 2 of thermal transferable ink (melting point 72° C., supercooling time 1 minute) with a dry thickness of 30ILm.

This thermal transfer material 3 is placed at a position where heat is applied by a thermal head 4,
The distance between the rollers 5a and 5b and the opposing transfer position is 3.
It was attached to the thermal copying apparatus shown in FIG. 1 set at 1.5 cm, and a pattern of heat was applied in dots to the thermal transfer material 3 from the support 1 side using the thermal head 4 (applied pulse width 1.1 m5 ec). .

Next, the thermal transferable ink layer 21 which has been melted or softened in a pattern as described above is made to face plain paper serving as a recording medium, and at the transfer position, the rollers 5a and 5b are applied with a linear pressure of 0.5
When a pressure of Kg/cm was applied, a transferred recorded image 22 was formed on the recording medium 6.

Next, the thermal transfer material 3 was wound around a roller 5a, and the adhesive ink layer 21 was repeatedly pressed against another recording medium supplied from the recording medium supplying means 7, resulting in a total of 10
A similar copy recorded image could be formed on two sheets of recording medium. These copied recorded images were visually good in print quality such as print density and sharpness, and almost no deterioration in print quality due to repeated pressure contact was observed.

Furthermore, the same procedure as above was carried out except that a heat-sensitive transfer material with a dry thickness of 50 gm was used for the heat-transferable ink layer, and copy recorded images with similarly good print quality were obtained on a total of 15 recording media. It was done.

[Brief explanation of drawings]

1 and 2 are both schematic cross-sectional views in the thickness direction of the support, FIG. 1 is a diagram showing an example of an apparatus system for carrying out the thermal copying method of the present invention, and FIG. FIG. 3 is a diagram for explaining another embodiment of the present invention. 1...Support 2...Thermal transfer ink layer 2...Ink layer 22 in adhesive state...Transfer recorded image 3...Thermal transfer material 4...Thermal heads 5a, 5b...・Pressure roller 6...Recording medium 7...Recording medium supply means 8...Document 8a...Image section 9...Radiation light ■": Figure 1 Figure 1 Port 2

Claims (1)

[Claims] selectively melting the thermal transferable ink by supplying patterned energy to the thermal transferable ink layer of a thermal transfer material comprising a layer of thermal transferable ink containing a supercooling polyamide resin provided on a support; It consists of a step of softening or softening, and a step of press-transferring the melted or softened ink to a recording medium facing the thermal transferable ink layer of the heat-sensitive transfer material, and is characterized in that the press-transfer step is carried out multiple times. A thermal copying recording method.