JPS60992A - Thermal transfer recording method - 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 The present invention relates to a thermal transfer recording method in which a thermal transfer material is formed on the spot without contaminating a recording medium, and recording is performed continuously.

In recent years, with the rapid development of the information industry, various information processing systems have been developed, and recording methods and devices suitable for each information processing system have also been developed and adopted. One such recording method is the thermal recording method.
The equipment used is light and compact, and there is no noise H'F.
It has excellent operability and maintainability, and has been widely used recently.

However, among the recording papers used in thermal recording methods, ordinary thermal recording paper is a color-forming processed paper containing a color former and a color developer, so it is expensive, and records can be tampered with. The paper has disadvantages in that it has poor storage stability, such as the paper easily developing color due to heat or organic solvents, and the recorded image fading in a relatively short period of time.

Thermal transfer recording method has recently been attracting particular attention as a method that maintains the advantages of the thermal recording method described in (1) and compensates for the disadvantages associated with the use of thermal recording paper.This thermal transfer recording method is generally , a heat-sensitive transfer material obtained by melt-coating a heat-transferable ink consisting of a colorant dispersed in a heat-melting binder on a sheet-like support -1- is used, and the heat-transferable ink layer of this heat-sensitive transfer material is The ink layer is superimposed on the recording medium so as to be in contact with the recording medium, and heat is supplied from the support side of the thermal transfer material using a thermal head to transfer the melted ink layer onto the recording medium. It forms a transfer ink image. According to this method, it is possible to maintain the above-mentioned advantages of the heat-sensitive recording method and use a single-pass paper as a recording medium, and also eliminate the disadvantages associated with the use of heat-sensitive recording paper as described in 1.

However, even in a thermal transfer recording method having such excellent characteristics, there are still some points that require improvement. One of these is that thermal transfer materials are inherently disposable, increasing recording costs. In order to eliminate this drawback, it has been proposed to use an endless belt-like support for the heat-sensitive transfer material and to incorporate the manufacturing process of the heat-sensitive transfer material by ordinary heat-melting coating into a heat-sensitive transfer recording system. However, in this case, it is necessary to maintain the hot-melt ink in a molten state while heating it.

Not only does this result in greater energy loss, but
It is extremely difficult to precisely control the thickness of a thermally transferable ink layer by coating.

Further, there are disadvantages in that the recording medium is stained and the transferred image becomes unclear due to insufficient cooling after the formation of the thermally transferable ink layer.

The main object of the present invention is to eliminate the inconveniences associated with the incorporation of the heat-melting coating process described above and to enable repeated use of thermal transfer materials by streamlining the manufacturing process of thermal transfer materials. The goal is to provide a recording method.

According to the research of the present inventors, in order to achieve the above object, heat-transferable ink can be obtained by atomizing heat-melting ink, electrostatically depositing it on a support and further rolling it. It has been found that forming an ink layer is extremely effective.

The thermal transfer recording method for a thermal transfer material of the present invention is based on the above-mentioned knowledge, and more specifically, the method is characterized by sequentially and repeatedly performing the following steps on an endless belt-like support. (a) A step of electrostatically adhering fine particles of a hot-melt ink made by dispersing a colorant in a hot-fusible binder to one surface of a support; (b) Rolling the fine particles on a support. (c) superimposing a recording medium so as to face the thermal transferable ink layer of the support; (d) patterning the thermal transferable ink layer facing the recording medium; a step of heating, and (p) a step of separating the support and the heat-transferable ink layer to leave an image of the heat-meltable ink according to the heating pattern on the recording medium.

Hereinafter, a preferred embodiment of the thermal transfer recording method of the present invention will be described in more detail with reference to the drawings as necessary. In the following description, "%" and "part" expressing quantitative ratios are based on weight unless otherwise specified.

The drawing is a schematic cross-sectional view in the thickness direction of a support, showing an outline of a thermal transfer recording system according to the method of the present invention. That is, first, the corona charger 3 charges the endless belt-shaped support 2 that is wound around the rolls 1a, 1b and the IC and moves continuously. Next, fine particles 5 of heat-melting ink are supplied to the charged support 2 using a rotating brush 4 and allowed to adhere thereto. Then, it is passed between a pair of pressure rolls 6a and 6b which are heated as necessary to form a smooth thermally transferable ink layer 5a to obtain a thermal transfer material. A recording medium 7 made of a sheet of paper or the like is brought into contact with the thermal transferable ink layer 5a of this thermal transfer material, and a thermal plate 9 is placed at a position facing the platen roll 8.
heat is supplied according to the desired print pattern. As a result, when the recording medium 7 is transferred to the thermal transfer material,
A desired ink pattern 5b is left on the recording medium.

On the other hand, the ink 5C remaining on the support la is removed by the cleaning blade 10 as required, and the support 2 renewed in this way is further subjected to the above series of steps 1 and 2.

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

As the support 2, conventionally known films and papers can be used as they are, as long as they have the necessary strength and flexibility. Plastic films with good heat resistance, cellophane, parchment paper, etc. can be suitably used. The thickness of the support is preferably about 2 to 15 microns when considering a thermal head as a heat source during thermal transfer, but for example, a heat source such as a laser beam that can selectively heat the thermal transferable ink layer is used. There are no particular restrictions when doing so.

In addition, when using a thermal head, the surface of the support that comes into contact with the thermal head may be made of silicone resin, fluororesin, polyimide resin, epoxy resin, phenol resin, or melamine resin.
1h, the heat resistance of the support can be improved by providing a heat-resistant protective layer made of nitrocellulose or the like, or it is also possible to use a support material that could not be used conventionally. Further, for reinforcement, the support body 2 can be multi-layered if necessary.

The fine particles 5 of the heat-melting ink are obtained by melting the heat-melting ink, which is made by dispersing a coloring agent in the heat-melting interlayer (this does not mean to exclude a state in which they are compatible), and then spraying and cooling it. It can be easily obtained by the method described below.

Examples of heat-melting binders include waxes such as Carnara/Kuwa-Nx, paraffin wax, Sasol Wa-Nx, microcrystalline wax, and Casta-Wa-Nx; nistearic acid, nolumitic acid, lauric acid, aluminum stearate, and stearic acid. Lead, barium stearate, zinc stearate, zinc palmitate, methyl hydroxystearate, higher fatty acids such as glycerol monohydroxystearate or their metal salts, derivatives of ester-9; polyethylene, polypropylene, polyisobutylene, polyethylene wax , polyethylene oxide, polytetrafluoroethylene, ethylene-acrylic acid copolymer: ethylene-ethyl acrylate copolymer,
111 of olefins such as ethylene-vinyl acetate copolymer
Thermoplastic resins made of polymers, copolymers, derivatives thereof, etc. are used. These heat-melting binders may be used alone or in combination of 50 to 150%.
Those having a melting point in the range of °C are preferably used.

As the colorant, various dyes, pigments, carbon blanks, etc. that are widely used in the fields of printing and recording can be used. The colorant is usually used in an amount of 5 to 50 parts per 100 parts of hot-melt paint.

The particle size of the fine particles 5 is not particularly limited, but is usually 0.1 to
A range of five rivers is preferably used.

In addition, the heat-melting ink is made of suitable 8'IIF plastic resin.
W may be used as a material and may be made into fine particles 5 by microencapsulation. Such microencapsulation improves the thermal sensitivity of thermal transfer recording by using a thermofusible binder with a relatively low melting temperature, while also reducing the tackiness or low melting point of the thermal transfer ink layer formed. Decrease in storage stability can be prevented.゛The thermoplastic resin used as the wall material during microencapsulation is preferably one that does not have compatibility with the heat-melting binder. It is preferable that the melting point or softening point is 10 to 50° C. higher than that of the meltable binder. Examples of preferred thermoplastic resins include:
Examples include: Namely, homopolymers of styrene and its substituted products such as polystyrene, poly p-chlorostyrene, and polyvinyl I/luene; styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, and styrene-vinyl I/luene copolymer. Union,
Styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer Polymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-methyl chloromethacrylate J1, ton polymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, Styrene-vinylethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-phtadiene copolymer, styrene-isoprene copolymer, styrene, styrene-acrylonitrile-
Styrenic copolymers such as indene copolymers, styrene-maleic acid copolymers, and styrene-maleic ester copolymers; or polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, Polyester, polyurethane, polyamide, epoxy resin, polyvinyl butyral, borodine, terpene resin, phenolic resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, etc. These thermoplastic resins can be used alone or in combination.

For microcapsulation, a method can be easily adopted in which the heat-melting ink is solidified and made fine as necessary, then dispersed in a solution of wall material heat++ l plastic resin, and the dispersion is spray-dried. Conventional microencapsulation methods such as , phase separation method, complex coacervation method, and interfacial m method are appropriately employed.

Microcapsules with a diameter of 0.1-10°, especially 2
-5 can be preferably used. The thickness of the coated thermoplastic resin may be in the range of 0.1-0.5 PL, and the coated thermoplastic resin in the microcapsule may be in the range of 5 to 50 parts with respect to 100 parts of the heat-melting binder. preferable.

In this way, the fine particles 5 of the thermofusible ink, which are microencapsulated as necessary, are transferred to the charged support 2.
After being electrostatically adhered to the ink layer 5a, the ink layer 5a is rolled while passing between a pair of rolls 6a and 6b, thereby forming a thermally transferable ink layer 5a. In order to reduce the pressure for forming the thermally transferable ink layer, the rolls 6a and 6b may be heated to a temperature that does not melt the thermally transferable ink layer 5.

The thermal transfer ink layer 5a is preferably formed to have a thickness of about 1 to 20 IL.

The heat-sensitive transfer recording process using the heat-sensitive transfer material having the formed heat-transferable ink layer 5a is not particularly different from that of a normal heat-sensitive transfer recording method. 0.5~5Kg/cr
d. The applied pulse Ill l ~5m5ec is preferably adopted. As other heat sources, laser light is also suitably used as described above.

In the illustrated example, the cleaning blade 1 removes the heat-melting ink 5c remaining on the support 1- after thermal transfer recording.
Although it is removed by 0, this is not necessarily necessary. This is because the method of the present invention includes a rolling step using means such as rolls 6a and 6b in the illustrated system, and even if the residual ink 5C remains attached to the support 2 during this rolling, This is because it is smoothed together with the additional heat-melting ink fine particles 5.

As described above, the present invention provides a thermal transfer recording method incorporating a step of electrostatically adhering fine particles of heat-melting ink to a support and forming a heat-transferable ink layer by rolling. Therefore, the heat-sensitive transfer material can not only be used repeatedly for 6 f times, but also has the following great advantages compared to the case where a heat-transferable ink layer forming step by ordinary heat-melting coating is incorporated. In other words, (a) the energy of the entire thermal transfer recording system is saved because the supply of a large amount of heat required for thermal melt coating is essentially unnecessary; and (b) recording due to insufficient cooling after the thermal transfer ink layer is formed. It can prevent staining of the medium and blurring of transferred images.
/\) Since the system has a built-in smoothing device (rolls 6a, 6b) for the thermal transferable ink layer, removal of residual ink is not necessary or the frequency of removal can be reduced, which saves ink. .

Hereinafter, the present invention will be explained in more detail with reference to Examples. Example 1 Carbon black 20 parts Paraffin wax (m, p, E18°C) 40 parts Ethylene/vinyl acetate copolymer 20 parts Carnauba wax 20 parts Xylene 200 parts After uniformly dispersing the composition using an attritor while heating it to 120°C, the thermal dispersion was spray-dried using a spray dryer to form a heat-melting binder with a particle size of 1 to 2 μm. Particles made of pigment (machi I).

Using a thermal transfer system as shown in the drawings, a support consisting of an endless polyester film was positively charged at +6 kV with corona electricity, and then the particles were adhered to the support with a rotating brush. Then, it was passed through a pressure roll with a linear pressure of 10 kg/cm and a surface temperature of about 50° C. to obtain a thermal transfer material having an ink layer with a thickness of 4 mm. Further, when this thermal transfer material was brought into close contact with plain paper and recording was performed using a thermal head at an applied pressure of 6 kg/crd and an applied pulse of 115 msec, clear printing was obtained.

In addition, by repeatedly forming a thermally transferable ink layer using the above method,
As a result of recording, it was possible to obtain multiple recordings without any deterioration in print quality.

Example 2 Carbon black 20 parts Paraffin wax (+o, p, 50°C) 40 parts Ethylene/vinyl acetate copolymer 20 parts Carnauba wax 20 parts Xylene 200 parts Using the above composition, the same procedure as in Example 1 was carried out. Colored particles were obtained. These particles are dispersed in a tetrahydrofuran solution of vinylidene chloride-acrylonitrile copolymer, and water is added dropwise into this dispersion to coat the colored particles with vinylidene chloride-acrylonitrile copolymer. Got the capsule. Recording was carried out using this capsule in the same manner as in Example 1, and as a result, good printing quality was achieved, and repeated recording was also possible.

[Brief explanation of drawings]

The drawing is a schematic cross-sectional view in the thickness direction of a support, showing an outline of a thermal transfer recording system according to the method of the present invention. la, lb, 1c**e roll 21I...Endless belt-like support 3...Fist corona charger 4...Φ rotating brush 5...fine particles of heat-melting ink 5a...thermal transfer ink layer 5b... -Printed ink image 5C...Residual ink 6a, 6b...Pressure roll 7Φ...Recording medium 8 -Fist -Platen roll 9...Thermal head 10...Cleaning blade.

Claims (1)

[Scope of Claims] (1) A thermal transfer recording method characterized by carrying out the following steps sequentially and repeatedly on an endless belt-like support. (b) A step of electrostatically depositing fine particles of a heat-melting ink made by dispersing a colorant in a hot-melting binder onto one surface of a support; (b) Rolling the fine particles on a support for thermal transfer. Step of forming a thermally transferable ink layer (c) 75 supports #1. (d) heating the thermally transferable ink layer facing the recording medium in a pattern; and (e) separating the support and the thermally transferable ink layer to form a heating pattern on the recording medium. The process of leaving a corresponding hot-melt ink image. 2. The method according to claim 1, which comprises removing the thermally transferable ink layer remaining on the support after step (e).