JP3242562B2 - Thermal transfer recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer recording medium in a thermal transfer recording apparatus used as an output terminal of an information processing apparatus such as a word processor and a facsimile.
In particular, the present invention relates to a thermal transfer recording medium in which an ink layer is formed of an ultraviolet curable resin.

[0002]

2. Description of the Related Art At present, various printers are used as output terminal devices of information processing apparatuses such as word processors, facsimile machines, computers, etc., and recording methods thereof include a thermal transfer method, an electrophotographic method, an ink jet method, and a wire dot method. Various methods have been proposed.

[0003] Among these, silence, low cost,
From the viewpoint of miniaturization adaptability, simple operability, and high reliability, a thermal transfer method using a heating resistor element array called a thermal head has been more widely used than in the past. It is expanding to youth and even hobby.

The thermal transfer method uses a heat transfer paper in which ink on a thermal transfer recording medium is melted by the heat of a thermal head and transferred to a recording paper made of plain paper, and a heat-sensitive paper which develops a color by heat above a set temperature. This thermal paper can be broadly classified into two types, a sublimation thermal transfer system that develops color by the heat of a thermal head. However, at present, the fusion thermal transfer recording system is mainly used in terms of cost.

FIG. 3 shows the basic principle of the above-mentioned fusion type thermal transfer system and the basic configuration of the thermal transfer recording medium 1 used in the fusion type thermal transfer system. The so-called thermal transfer recording medium 1 has a structure in which an ink layer 7 is laminated on a base material 2.

As the substrate 2 of the thermal transfer recording medium 1, a polymer resin film having a film thickness of usually 1 to 12 μm is used. As the material of the substrate 2, polyethylene terephthalate, polyethylene naphthalate, polyimide ,
General-purpose resins such as polyetheretherketone and aramid are used.

[0007] Further, on the back surface 2a of the substrate 2, the wear of the thermal head due to the sliding contact is reduced, the running of the ink ribbon as the thermal transfer recording medium 1 is stabilized, and the ink ribbon is fused to the ink surface at the time of winding. In general, the lubricating layer 4 is applied for the purpose of prevention or the like.

The ink layer 7 of the thermal transfer recording medium 1 is composed mainly of a heat-fusible resin having good adhesion between a heat-fusible substance such as wax and recording paper, and various pigments and various plasticizers as coloring agents. , A dispersant, an antioxidant and the like are added in trace amounts. Examples of the wax used in the ink layer 7 include carnauba wax, candelilla wax, rice wax, paraffin wax, microcrystalline wax, polyethylene wax, and the like, and these are used alone or in combination.

The heat-meltable resin used for the ink layer 7 includes ethylene-based copolymers such as ethylene-vinyl acetate copolymer, ethylene-vinyl butyrate copolymer, ethylene-acrylic copolymer, and polylauryl. Examples include poly (meth) acrylates such as methacrylate and polyhexyl acrylate, and vinyl chloride copolymers such as polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, and vinyl chloride-vinyl alcohol copolymer. Can,
These resins are used alone or in combination.

When the thermal transfer recording medium 1 is formed, a hot-melt method is used, that is, an ink containing a heat-fusible substance such as the wax and the heat-fusible resin as main components is heated and melted. After being applied to the substrate 2, it is formed by cooling and solidifying, or a solvent method, that is, the substrate 2 is immersed in a resin solution or a dispersion thereof, and the solvent is evaporated off to leave an adhered film. It was formed by the thing.

[0011]

However, in the conventional thermal transfer recording medium 1, when it is formed by the hot melt method, it is necessary to always melt the ink, and the apparatus becomes large and the power consumption increases. There was a problem that it would. On the other hand, when formed by the solvent method,
It must be heated to provide the problem of solvent disposal and the heat of evaporation that removes the solvent, which consumes considerable energy for heating the air and other equipment required for this heating, such as electric furnaces. There was a problem.

On the other hand, in recent years, ultraviolet curable resins have attracted attention in the fields of paints and printing inks as resins having characteristics of no pollution and energy saving, and attempts have been made to use them for the thermal transfer recording medium 1. ing.

This UV-curable resin has few pollution problems, and usually requires no heating at the time of curing and only needs to irradiate UV rays, so that energy consumption is small. Has the advantage of being improved.

However, even when the thermal transfer recording medium 1 is formed by applying a general one of the ultraviolet curable resins to the base material 2, the glass transition temperature, that is, the state of the viscous region or the elastic region is hard non-hard. Since the temperature at which the state changes to the crystalline region is high in many cases, the printing obtained by the thermal transfer recording medium 1 has a problem that when the glass transition temperature is high, printing cannot be performed at all while the ink layer 7 is in a cured state. there were.

The present invention has been made in view of the above problems, and has as its object to provide a thermal transfer recording medium that can be easily formed and that can provide good printing.

[0016]

In order to achieve the above object, the thermal transfer recording medium according to the first aspect of the present invention is characterized in that it undergoes radical polymerization by light and has a glass transition temperature of 0 ° C. or lower. Is formed in a recording material, and the recording material is irradiated with light to radically polymerize the monomer to form the polymer, thereby forming an ink layer. By employing such a configuration, an ink layer can be formed only by irradiating light, and a thermal transfer recording medium capable of performing good printing can be obtained.

The thermal transfer recording medium according to the second aspect is characterized in that the amount of the monomer according to the first aspect is 10 to 9
5 parts by weight, the amount of the hot-melt substance is 5 to 80 parts by weight, and the amount of the coloring material is 1 to 25 parts by weight.
By adopting such a configuration, it is possible to easily form a thermal transfer recording medium capable of more reliably performing good printing.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to an embodiment shown in the drawings.

First, the thermal transfer recording medium 1 of the present invention will be described with reference to FIG.

As shown in FIG. 1, a thermal transfer recording medium 1 of the present invention comprises an ink layer 3 made of a thermal transfer recording material on a substrate 2.
Are laminated, and a back surface 2a of the base material 2 is provided.
Has a lubricating layer 4 formed thereon. The recording material for thermal transfer constituting the ink layer 3 is mainly composed of an ultraviolet curable resin which is cured by irradiating ultraviolet rays as light, and contains a heat melting substance, a coloring agent, and other trace additives as necessary.
The composition is about 10 to 10 parts by weight.

The base material 2 of the thermal transfer recording medium 1 has a thickness of 0.1 mm.
A polymer resin film having a thickness of 5 to 20 μm, preferably 2 to 10 μm is used. If the thickness of the substrate 2 is less than 0.5 μm, the strength is insufficient, and if it is more than 20 μm, the sensitivity is insufficient, which is not preferable. As the material of the polymer resin film, polyethylene terephthalate, polyphenylene sulfide, polyimide, polyethylene naphthalate, polycarbonate, aramid and the like are suitable.

The lubricating layer 4 having a thickness of 1 μm or less, preferably 0.5 μm or less, is
Is formed with a fluorine-based or silicon-based coating agent. If the thickness is 1 μm or more, the sensitivity becomes insufficient, which is not preferable. This lubrication layer 4
, The wear of the thermal head due to the sliding contact is reduced, the running of the ink ribbon as the thermal transfer recording medium 1 is stabilized, and the fusion of the ink ribbon with the ink surface when the ink ribbon is wound can be prevented.

Next, an ultraviolet curable resin which is a main component of the recording material for thermal transfer will be described.

First, the general UV-curable resin includes a photopolymerizable prepolymer, a photopolymerizable monomer, and a photoinitiator.
The photopolymerizable prepolymer is usually added in the range of 0 to 99 parts by weight, and is an important component constituting the skeleton of the resin.

The photopolymerizable prepolymer is a polymer which is further polymerized by a photochemical action, and is sometimes called a photopolymerizable unsaturated polymer or a photopolymerizable oligomer.

The photopolymerizable monomer plays a role of a diluent for the photopolymerizable prepolymer. Usually, the photopolymerizable monomer is added in an amount of 0 to 99 parts by weight to ensure practical workability of the ink. The terminal itself participates in the polymerization reaction by the action of the terminal functional group at the time of ultraviolet irradiation. The photopolymerizable monomer can be classified into a monofunctional monomer and a polyfunctional monomer according to the number of functional groups. Particularly, the polyfunctional monomer plays a role of a cross-linking agent that forms a bridge between polymers.

The photoinitiator absorbs ultraviolet rays to trigger a polymerization reaction.

Among the general UV-curable resins having the above-mentioned structure, the UV-curable resin in the present embodiment is particularly one that plays the role of the photopolymerizable monomer and the photopolymerizable prepolymer. When irradiated with ultraviolet rays, a radical polymerization reaction is performed, and an acrylic monomer having a glass transition temperature of the polymer of 0 ° C. or less is used, and the acrylic monomer is used in an amount of 10 to 95 parts by weight, preferably 20 to 80 parts by weight. Contains parts by weight. If the amount of the acrylic monomer is less than 10 parts by weight, the viscosity of the coating material at room temperature becomes higher and coating cannot be performed, and if it is more than 80 parts by weight, the thermal transferability is poor.

Here, as described above, the glass transition temperature is a temperature at which a state of a viscous region or an elastic region changes from a state of a hard amorphous region to a state of a hard amorphous region. And the temperature determined by the curing temperature. Then, when the polymer generated by radical polymerization has a glass transition temperature of 0 ° C. or less, an ink layer 3 suitable as the thermal transfer recording medium 1 is formed,
Further, when the glass transition temperature is −10 ° C. or lower, the ink layer 3 on which better recording can be performed can be formed. If the polymer has a glass transition temperature of 0 ° C. or more,
Since the thermal transferability is inferior and a low melting point wax must be used as the heat melting substance, the printed state is liable to be stained or crushed.

The above-mentioned radical polymerization reaction is one of ultraviolet curing reactions. This reaction requires a photoinitiator and usually includes a start reaction, a growth reaction, a chain transfer reaction and a termination reaction. Divided into reactions. Among these, the initiation reaction is a reaction that activates the photoinitiator and generates radicals to activate the photopolymerizable monomer when the ultraviolet curable composition is irradiated with ultraviolet rays. The main methods for activating the photoinitiator include photocleavage, hydrogen abstraction, and electron transfer. In addition, the growth reaction refers to a reaction in which the degree of polymerization of the radical generated in the initiation reaction gradually increases, and the chain transfer reaction refers to a reaction in which the radical is transferred to another molecule. The terminating reaction refers to a reaction in which radicals disappear and the radical reaction ends.

On the other hand, in the ultraviolet curable resin in the present embodiment, the acrylic monomer is used, and the photopolymerizable prepolymer is not blended. However, the desired effect can be sufficiently obtained by using only the photopolymerizable monomer. Note that, depending on the type of the acrylic monomer, a small amount of the photopolymerizable prepolymer may be used to improve the polymerization rate.

Next, as the photopolymerizable monomer used for the recording material for thermal transfer, 2-ethylhexyl carbitol acrylate, phenol EO-modified acrylate, nonylphenol EO-modified acrylate and the like can be preferably mentioned.

Examples of photoinitiators include biacetyl, acetophenone, benzophenone, Michler's ketone, benzyl, benzoin, benzoin isobutyl ether, benzyl dimethyl ketal, tetramethylthiuram sulfide, azobisisobutylnitrile, benzoyl peroxide, di-tert-butyl. Peroxide, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one,
-(4-isopropylphenyl) -2-hydroxy-2
-Methylpropan-1-one, 2-chlorothioxanthone, methylbenzoylformate and the like can be mentioned as preferable examples.

Next, a heat-fused substance as another component of the recording material for thermal transfer will be described.

Examples of the heat-fusible substance include petroleum wax such as paraffin, vegetable wax such as carnauba and candelilla, animal wax such as beads, coal wax such as montan, and synthetic wax such as Fischer-Tropsch, or Hot-melt or softening resins such as low molecular weight polyethylene, ethylene vinyl acetate, and ethylene ethyl acrylate are used. The amount of these resins is 5 to 80 parts by weight, preferably 10 to 7 parts by weight.
0 parts by weight. If the amount of the hot-melt substance is 5 parts by weight or less, the thermal transferability is poor,
If the amount is more than 80 parts by weight, the viscosity of the coating material at room temperature is too high to apply, which is not preferable.

Examples of the colorant include black pigments such as carbon black, acetylene black and oil black, white pigments such as titania and calcium carbonate, and known dyes such as yellow, magenta and cyan. The color tone and the like can be adjusted to a desired state by appropriately changing the amount of the pigment or dye added. Specifically, the amount is 1 to 25 parts by weight, preferably 5 to 20 parts by weight. When the amount is 1 part by weight or less, the coloring power becomes insufficient, and when the amount is 25 parts by weight or more, the coating agent becomes powdery and can be applied as it is. Will be gone.

Further, the trace additives include oils such as silicone oil, liquid waxes such as jojoba oil,
Examples thereof include a tackifying resin such as hydrogenated rosin and hydrogenated terpene, and a dispersant. The compounding amount is 0 to 20 parts by weight, preferably 0 to 10 parts by weight. If the oil is added in an amount of 20 parts by weight or more, stains are likely to occur at the time of printing, and if the tackifying resin is added in an amount of 20 parts by weight or more, it becomes difficult to remove the ink from the base material 2. Not preferred.

The recording material for thermal transfer may further contain additives such as a sensitizer, a pigment, a filler and a leveling agent, if necessary.

Next, a method of forming the thermal transfer recording medium 1 will be described.

First, the respective materials constituting the above-mentioned recording material for thermal transfer are mixed using a usual stirrer at a temperature at which the hot-melt substance is melted. Then, this is cooled to room temperature, and then milled by an ordinary dispersing machine such as a three-roll mill to prepare the recording material for thermal transfer. During the milling, heating may be performed slightly to improve the dispersion efficiency.

Next, this recording material for thermal transfer is applied at room temperature to a usual coating method such as direct gravure,
The substrate 2 is coated with a knife, blade, reverse, wire bar, rod, or the like so as to have a uniform film thickness. During this coating, heating may be performed slightly to improve the coating efficiency.

Next, as shown in FIG. 2, the base material 2 of the thermal transfer recording medium 1 on which the thermal transfer recording material is
From the side, that is, from the back surface 2a side, ultraviolet light is entirely radiated by the ultraviolet light irradiator 5. As a light source of the ultraviolet irradiator 5,
At least one UV-emitting device such as a low-pressure or high-pressure mercury lamp, a mercury-xenon lamp, and a metal halide lamp is used. The ultraviolet light emitted from the ultraviolet irradiator 5 is diffused light or collected through a condenser lens (not shown). Any of light may be used.

At this time, before the ultraviolet irradiation by the ultraviolet irradiator 5, the surface of the recording material for thermal transfer is formed in an anaerobic atmosphere in advance, so that the surface of the recording material for thermal transfer has a flat plate shape as a blocking means for shielding the atmosphere. The plate 6 is bonded so as to be in close contact. The plate 6 only needs to cover at least the surface of the ink layer 3 in a range where the ultraviolet rays from the ultraviolet irradiator 5 can reach.

The plate 6 may be made of polyethylene, polypropylene, polyester, nylon, polystyrene,
Plastics such as polyvinyl alcohol, polyvinyl chloride, polycarbonate, polyurethane, fluororesin, methyl methacrylate, polyacrylonitrile, polybutene, polyimide, polyarylate, polyethersulfone, polyetheretherketone, polysulfone, polyetherimide, and aramid films Film, copper, iron, aluminum, stainless steel,
It may be a metal plate such as chromate plating, nickel plating, or alumite. The plate body 6 may be made of a plate-like inorganic material such as glass or ceramic or a plate-like rubber material such as silicon rubber.

Then, the surface of the ink layer 3 is covered with the plate body 6 to make the surface an anaerobic atmosphere,
When the ultraviolet ray is irradiated from the ultraviolet irradiator 5 to the ink layer 3 through the substrate, the ultraviolet ray reaches the ink layer 3 via the base material 2, but the air does not exist on the surface of the ink layer 3. Therefore, the radical polymerization reaction on the surface of the ink layer 3 is not hindered by oxygen in the atmosphere, and the ink layer 3 is hardened almost uniformly on the surface and inside in a short time, and the thermal transfer recording medium 1 is formed. Will be done.

[0046]

Next, specific examples of the thermal transfer recording medium 1 of the present invention will be described.

As the polymer resin film of the base material 2 of the present embodiment, a tolerina (manufactured by Toray Co., Ltd.) having a thickness of 4 μm is used, and the acrylic monomer which is a main component of the recording material for thermal transfer has a glass transition. M-120 with a temperature of -65 ° C
(Manufactured by Toa Gosei) and M-111 having a glass transition temperature of 17 ° C.
(Toa Gosei) and 55 parts by weight of a composition obtained by mixing at various compounding ratios shown in Table 1 below, and 25 parts by weight of Sasol A-1 (manufactured by Sasol) as the hot-melt substance were used. 1 wax 655 (made by Japan Natural Products)
0 parts by weight, 5 parts by weight of MA-100 (manufactured by Mitsubishi Kasei) as the coloring agent, and 5 parts of CLEARON P-85 (manufactured by Yashara Chemical) as a tackifying resin.
We decided to use parts by weight.

Then, in order to prepare a recording material for thermal transfer, all the materials to be used as the components of the recording material for thermal transfer are stirred and mixed at a temperature of 90 ° C. by a stirrer for 30 minutes, and then cooled to room temperature. This is milled with a three-roll mill to obtain a desired recording material for thermal transfer. In order to form a thermal transfer ribbon as the thermal transfer recording medium 1, the recording material for thermal transfer is applied by an offset gravure machine onto the base material 2, a 4 μm thick tolerina having a thickness of 3 μm, to form an ink. Layer 3 was formed.
Thereafter, a polyethylene film was superimposed on the coated product and irradiated with 5000 (mj / cm ² ) ultraviolet light from a high-pressure mercury lamp to be cured, thereby forming a thermal transfer ribbon.

This thermal transfer ribbon was printed on a word processor paper for thermal transfer (manufactured by Union Chemical Car) using a JT-144 (manufactured by Star) thermal transfer printer.

Regarding the quality of the printing condition, the acrylic monomers M-120 and M-111 were used.
Are shown in Table 1 together with the compounding ratio thereof and the glass transition temperature of the ultraviolet curable resin prepared by mixing them.

[0051] As can be seen from Table 1, M-120 and M-11
In the case where the UV-curable resin prepared by mixing 1 with the above has a glass transition temperature of −4 ° C., printing with the thermal transfer ribbon exhibits a good state, and the UV-curable resin has a glass transition temperature of −14 ° C. or less. With a transition temperature, printing with the thermal transfer ribbon exhibited a very good condition.

On the other hand, when the ultraviolet curable resin had a glass transition temperature of 0 ° C. or more, the printing by the thermal transfer ribbon was blurred or no printing was performed.

Next, as a comparative example to this embodiment,
Comparative Examples 1 and 2 are shown.

First, Comparative Example 1 will be described. In Comparative Example 1, only M-111 was used as an acrylic monomer, beeswax (manufactured by Nippon Natural Products) was used as the hot-melt substance, and the composition of the present invention was used as another thermal transfer recording material composition. The thermal transfer recording medium 1 was prepared using the same composition as described above and using the same forming method.
Is formed.

More specifically, a 4 μm-thick Torelina (manufactured by Toray Co., Ltd.) was used as the polymer resin film of the base material 2, and the acrylic material having a glass transition temperature of 17 ° C. was used as the thermal transfer recording material. 30 parts by weight of M-111 (manufactured by Toa Gosei) as a monomer, 60 parts by weight of beeswax (manufactured by Nippon Natural Products) as a hot-melt substance, and 5 parts by weight of MA-100 (manufactured by Mitsubishi Chemical) as a coloring agent Parts, CLEARON P-85 (manufactured by Yasuhara Chemical Co., Ltd.), which is a tackifying resin, was used at a mixing ratio of 5 parts by weight.

Then, a recording material for thermal transfer was prepared by the same forming method as that described in Examples of the present invention, and a thermal transfer recording medium 1 was further formed to observe the printing state. As a result, the printed portion became dirty. The reason for this is that M
This is because the glass transition temperature of −111 is 17 ° C., which is inferior in thermal transferability, and the ink was softened by mixing beeswax, which is a hot-melt substance having a low melting point, to improve this.

Next, Comparative Example 2 will be described. In Comparative Example 2, the recording material for thermal transfer used in each of the above Examples was changed to SEPTER (manufactured by Dainippon Ink), which is a commercially available UV ink.

The SEPTER is stirred and mixed at room temperature with a stirrer for 30 minutes and milled with a three-roll mill to obtain a desired recording material for thermal transfer. In order to form a thermal transfer ribbon which is the thermal transfer recording medium 1, the thermal transfer recording material is applied to the 4 μm thick tolerina which is the base material 2 by an offset gravure machine so as to have a thickness of 3 μm. An ink layer 3 was formed. Thereafter, a polyethylene film was superimposed on the coated product and irradiated with 5000 (mj / cm ² ) ultraviolet light from a high-pressure mercury lamp to be cured, thereby forming a thermal transfer ribbon.

This thermal transfer ribbon was printed on a word processor paper for thermal transfer (manufactured by Union Chemical Car) using a JT-144 (manufactured by Star) thermal transfer printer, and the printed state was observed. Did not. This is because ordinary ultraviolet curable resin does not melt after being cured by heating with a thermal head of a thermal transfer device.

From the above results, if the ultraviolet-curable resin having a glass transition temperature of 0 ° C. or less is used for the thermal transfer recording material, the thermal transfer recording medium 1 on which good printing can be performed is simply irradiated with ultraviolet light. It can be formed by such a simple method. Furthermore, if the ultraviolet curing resin having a glass transition temperature of −10 ° C. or less is used, the thermal transfer recording medium 1 on which better printing can be performed can be obtained.

Therefore, in one embodiment of the present invention, since an ultraviolet curable resin is used as the thermal transfer recording material constituting the thermal transfer recording medium 1, ultraviolet light is applied when the thermal transfer recording medium 1 is formed. It can be easily formed simply by irradiation. Further, the apparatus for forming the thermal transfer recording medium 1 only needs to have an ultraviolet irradiation apparatus and does not need a large-sized apparatus. Therefore, power consumption is small and cost can be reduced.

The present invention is not limited to the above-described embodiment, but can be variously modified as needed.

For example, the UV-curable resin is not limited to the acrylic monomer described in the above embodiment, but may be any acrylic monomer having a glass transition temperature of 0 ° C. or lower.

[0064]

As described above, according to the thermal transfer recording medium of the present invention, a thermal transfer recording medium capable of performing good printing can be formed by a simple method of merely irradiating ultraviolet light.

Accordingly, there are the effects that the power consumption and cost required for forming the thermal transfer recording medium can be reduced.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing an embodiment of a thermal transfer recording medium according to the present invention.

FIG. 2 is an explanatory view showing a method for forming a thermal transfer recording medium according to an embodiment of the present invention.

FIG. 3 is a side sectional view showing a conventional thermal transfer recording medium.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermal transfer recording medium 2 Base material 3 Ink layer 4 Lubrication layer 5 Ultraviolet irradiation device 6 Plate

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B05D 7 / 04,5 / 04 B41M 5/30 B32B 27 / 00,27 / 30

Claims (2)

(57) [Claims] 1. A thermal transfer recording medium comprising an ink layer laminated on a film substrate, wherein the monomer is radically polymerized by light, and the polymer has a glass transition temperature of 0 ° C. or less; A thermal transfer recording medium, wherein the monomer of a recording material containing at least a hot-melt substance and a colorant is radically polymerized by light to form the polymer. 2. The amount of the monomer is 10 to 95 parts by weight, the amount of the hot melt is 5 to 80 parts by weight, and the amount of the coloring material is 1 to 25 parts by weight. The thermal transfer recording medium according to claim 1, wherein