JPH0592668A - Thermal transfer recording medium - Google Patents

Abstract

PURPOSE:To apply printing having good resolving power and good high speed followability to rough surface paper by using a specific polyether resin and an ethylene/vinyl acetate resin as the ink binder of hot-melt ink based on a color forming component and a binder in a specific ratio. CONSTITUTION:Hot-melt ink wherein 5-50wt.% of a polyether resin (a) having a bisphenol skeleton in its molecule and having a hydroxyl group at its molecular terminal and 30-90wt.% of an ethylene/vinyl acetate resin are added to an ink binder (contents: b>=a) and the use amount of the polyether resin is 3-30% by wt. of the total ink compound excepting a volatile component such as a solvent is applied to a base material through an intermediate release layer. Further, an org. fine powder or an inorg. fine powder such as silica can be also compounded. By this constitution, high speed followability, high printing quality and printing fastness can be simultaneously satisfied.

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 used in a thermal transfer recording device such as a printer or a facsimile, and more particularly to a thermal transfer recording medium satisfying high-speed followability, high print quality and print robustness at the same time. ..

[0002]

2. Description of the Related Art In a thermal transfer recording system, a thermal transfer recording medium is prepared by coating at least one layer of a thermal melting ink on a sheet-shaped base material, and the thermal melting recording layer of the thermal transfer recording medium is a transfer paper. Is a recording system in which the ink layer is heated and melted by a heating head from the substrate side of the thermal transfer recording medium to obtain a transferred image on the transfer paper. According to this method, a device used is low in noise, excellent in operability and maintainability, and plain paper can be used as a transfer target paper, and thus has been widely used in recent years.

[0003]

As the performance of thermal transfer printers has improved, there has been a demand for a composite technique such as high-speed printing on rough surface paper. Considering the speedup of the printer, the high-speed followability of the ribbon (higher sensitivity)
Is a big issue. In order to improve the high-speed followability while maintaining the coating of the rough surface paper, conventionally, a resin component was introduced into the binder (Japanese Patent Laid-Open Nos. 54-87234, 54-163044 and 56-98).
No. 269, No. 62-130887), or application of a resin-based overcoat layer to wax ink (JP-A-61-242893).
Etc. have been dealt with. However, even with these techniques, it is difficult to say that they are sufficient in terms of performance balance, and improvements have been desired. Therefore, an object of the present invention is to provide a thermal transfer recording medium having a high resolution (covering) on a rough surface paper and capable of printing with high speed followability.

[0004]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a polyether resin and an ethylene vinyl acetate resin having a bisphenol skeleton in the molecule and a hydroxyl group at the molecular end are used as a coloring component and a binder. The inventors have found that the above object can be achieved by using a specific ratio as an ink binder for a hot-melt ink, which is the main component, and have completed the present invention.

That is, the present invention provides (a)
5 to 50% by weight of a polyether resin having a bisphenol skeleton in the molecule and a hydroxyl group at the end of the molecule, and (b)
All inks containing 30 to 90% by weight of ethylene vinyl acetate resin (however, the content is (b) ≧ (a)) and the amount of the (a) polyether resin used excludes volatile components such as solvents. A thermal transfer recording medium is provided by coating 3 to 30% by weight of a heat-meltable ink in a formulation on a substrate through an intermediate release layer.

The (a) polyether resin having a bisphenol skeleton and having a hydroxyl group at the molecular end used in the present invention is represented by the following formula:

[0007]

[Chemical 1]

A bisphenol compound and its propylene oxide adduct, ethylene oxide adduct, and other diols, and an aliphatic epoxy compound having two epoxy groups in the molecule, an alicyclic epoxy compound, and an aromatic epoxy compound. Polyether resin obtained by addition polymerization, polyether resin reacted so that epoxy group does not remain at the terminal of the molecule, bisphenol epoxy resin and two hydroxyl groups in the molecule, hydroxyl group and amino group, or hydroxyl group and carbonyl As the polyether resin obtained by addition polymerization with a compound having a group, a polyether resin which is reacted so that an epoxy group does not remain at the molecular end is used. In this case, a branched or crosslinked polyether may be prepared by further using an epoxy compound having three or more epoxy groups in the molecule. Of course, the polyether resin according to the present invention is not limited to these production methods.
The main role of the polyether resin according to the present invention is to impart cohesive force for forming a film to a molten ink during printing,
It is to impart fastness to the printed matter after printing, and in order to achieve the purpose, it is appropriate to add 5 to 50% by weight of the polyether resin in the ink binder. If the blending amount is less than 5% by weight, there is a problem in the fastness after printing, and the ink has weak scratch resistance. On the contrary, when the blending amount exceeds 50% by weight, the cohesive force is excessively increased, and the transferability to the paper is deteriorated in the high speed printing process.
The ink quality is poor. Further, the polyether resin according to the present invention is blended so that the amount used in the ink formulation excluding volatile components such as a solvent is 3 to 30% by weight. If the amount of the polyether resin used is more than 30% by weight, the performances such as high speed followability and resolution cannot be satisfied.

The ethylene vinyl acetate resin (b) used in the present invention is mixed in the ink binder excluding the coloring component in an amount of 30 to 90% by weight. The molecular weight is not particularly limited. Taking commercially available ethylene vinyl acetate resin as an example, EV-45X, EV-40X,
EV-40Y, EV-40W, EV-5772, EV-5773, EP-4022W, ELVA
X-250W, EV-210, EV-220, EV-250, EV-260, EV-310, EV
Resins available under the trade names of -360, EV-410, EV-420, EV-450, EV-460, etc. can be used. The main role of the ethylene vinyl acetate resin according to the present invention is to impart tackiness to paper in a high speed printing process, and therefore it is necessary to blend the ethylene vinyl acetate resin in the ink binder in an amount of 30% by weight or more. .. If the blending amount is less than 30% by weight, the adhesion to the paper during printing will be poor, and the ink will not be printed at high speed and will not follow at high speed. On the other hand,
If it exceeds 90% by weight, the melt viscosity of the ink increases more than necessary, and the running property in the printer is deteriorated. Further, the adhesive component becomes excessive on the ink surface, and the blocking resistance decreases.

The ethylene vinyl acetate resin according to the present invention has a vinyl acetate component content of 10 to 47% by weight.
However, it is more preferable that the content of vinyl acetate component is 23 to 43% by weight. If an ethylene vinyl acetate resin having a low vinyl acetate component content is used, the tackiness of the ink is reduced and the high-speed followability is reduced. On the other hand, when an ethylene vinyl acetate resin containing a large amount of vinyl acetate component is used, the tackiness of the ink becomes too high, the blocking resistance is lowered, and a stringing phenomenon occurs. In the present invention, the above (a) polyether resin and (b) ethylene vinyl acetate resin are used so that the content in the ink binder is (b) ≧ (a). Further, the total amount of the (a) polyether resin and the (b) ethylene vinyl acetate resin is preferably 50% by weight or more in all binders.

In the present invention, examples of binders other than the above-mentioned (a) polyether resin and (b) ethylene vinyl acetate resin include waxes such as paraffin wax, carnauba wax and rice bran wax.

The thermal transfer recording medium of the present invention comprises a heat-meltable ink obtained by mixing the above-mentioned polyether resin and ethylene-vinyl acetate resin according to the present invention, a colorant, and various additives which are optionally used. It is formed by applying it on a material and setting an ink layer. At this time, an intermediate release layer is provided between the base material and the ink layer. The intermediate release layer includes silicone resins, higher fatty acids, higher fatty acid metal salts,
Fatty acid derivatives, higher alcohols, waxes and the like are used. Waxes are particularly preferably used. For example, paraffin wax, montan wax, carnauba wax, beeswax, wood wax, candelilla wax, low molecular weight polyethylene, α-olefin oligomers, and binders of hot-melt inks such as modified products thereof. Known waxes that have been conventionally used as the material can be mentioned. The waxes may be used alone or in combination of two or more. In addition to waxes, resins such as ethylene-acrylic acid copolymer, ethylene vinyl acetate, polyethylene and petroleum resin may be added in order to improve the strength of the coating film.

As the colorant used for preparing the ink, black dyes and pigments such as carbon black, oil black and graphite; CI Pigment Yellow 1, the same 3, the same 74, the same 9
Acetoacetic acid arylamide-based monoazo yellow pigments such as 7 and 98 (fast yellow); CI Pigment Yellow12 and 1
Acetoacetic acid arylamide-based bisazo yellow pigments such as 3 and 14; CI Solvent Yellow19, 77 and 79, CIDisperse
Yellow dyes such as Yellow 164; CI Pigment Red 48, 49:
Red or red pigment such as 1, 53: 1, 57: 1, 81, 122, 5 etc .; red dye such as CI Solvent Red 52, 58, 8 etc .; copper phthalocyanine such as CI Pigment Blue 15: 3 And blue-based dyes and pigments such as derivatives and modified products thereof, and colored or colorless sublimable dyes, conventional printing inks,
Well-known dyes and pigments for other coloring applications can be used. These dyes and pigments may be used alone or in combination of two or more.
Of course, the color tone may be adjusted by mixing with an extender pigment or a white pigment. Furthermore, in order to improve the dispersibility in the binder material component, the surface of the colorant is treated with a surfactant, a coupling agent such as a silane coupling agent, or a polymer material,
A polymer dye or a polymer graft pigment may be used.

Further, in order to improve the blocking resistance of the ink ribbon, an organic fine powder or an inorganic fine powder other than a coloring agent such as carbon black is further added in an amount of 0.5 to 0.5 in the total ink composition.
It can be blended at 10% by weight. These fine powders are not intended for coloring, but are added for controlling the surface property of the ink surface for the purpose of improving blocking resistance, running property and the like. Fine powders that can be used include inorganic powders such as metals, metal oxides, silica, zirconia, calcium carbonate, and talc, organic powders such as styrene, polyester, polyurethane, polyamide, and acrylic resins,
Also, any material such as silicone resin powder, fluorinated ethylene resin powder, fluorinated carbon powder, etc. can be used as long as it maintains the powder shape regardless of the material. The shape of the fine powder is spherical, needle-like, plate-like, etc. and is not particularly limited. Further, it is suitable that the average particle diameter of the fine powder is 0.01 to 10 µ. If the average particle size of the fine powder is less than 0.01 μ, the effect of the powder addition cannot be sufficiently exerted, and conversely, if it exceeds 10 μ, the ink surface is too rough and transfer inhibition occurs.

The base material of the thermal transfer recording medium of the present invention includes:
Papers such as capacitor paper and glassine paper, thin films and films of plastics such as polyester such as polyethylene terephthalate, polyimide, polycarbonate, polyamide, polyethylene and polypropylene are used. The thickness of the substrate is preferably in the range of about 2 to 20μ.
When recording using a thermal head or the like, in order to improve heat resistance, running property, etc. on the side of the substrate that contacts the thermal head, silicone-based or fluorine-based compound, resin layer or cross-linked polymer layer, metal You may provide a layer etc.

[0016]

EFFECT OF THE INVENTION According to the thermal transfer recording medium of the present invention, it is possible to print with high sensitivity and good cutting robustness using various printers from a low speed printer to a maximum speed printer (about 70 characters / second). can get.

[0017]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. In the following examples, parts and% represent weight units unless otherwise specified.

Example 1 Polyether resin A (molecular weight 3000) produced from bisphenol-based epoxy resin "Epiclone" (manufactured by Dainippon Ink and Chemicals) and ethylene vinyl acetate resin "EV-40Y" (vinyl acetate) 41% by weight, Mitsui DuPont Polychemical Co., Ltd.), carnauba wax, HN
A solvent-based ink is prepared by dispersing P-3 (paraffin wax) and carbon black in methyl isobutyl ketone at a solid concentration of 20% using the amounts shown below. -Polyether resin A 25 parts-EV-40Y 35 parts-Carnauba wax 5 parts-HNP-3 5 parts-Carbon black 30 parts This solvent-based ink has a heat-resistant lubricating layer (mainly composed of nitrocellulose and silicone oil) Of a polyethylene terephthalate film having a wax intermediate release layer formed on the other surface thereof is applied to the intermediate release layer side by a wire bar coater to prepare an ink film. This film is cut into a predetermined width to make an ink ribbon, and a commercially available personal word processor (Fujitsu Oasis 30AX II, 70 characters /
Second), the results shown in Table 1 were obtained.
That is, an ink ribbon having excellent printing fastness and resolution and good high-speed followability was obtained.

Example 2 Polyether resin B (molecular weight 2000) produced from "Epiclone" and bisphenol A, "EV-220" which is ethylene vinyl acetate resin (vinyl acetate content 28% by weight, DuPont Mitsui Polychemical Co., Ltd. )), Rice bran wax, a dispersant, carbon black and a dye are dispersed in methyl isobutyl ketone at a solid content concentration of 25% to prepare a solvent-based ink.・ Polyether resin B 15 parts ・ EV-220 33 parts ・ Nuka wax 15 parts ・ Dispersant 2 parts ・ Carbon black 30 parts ・ Dye 5 parts Ink ribbon using the same solvent-based ink as in Example 1 Was prepared and evaluated in the same manner, the results shown in Table 1 were obtained. That is, an ink ribbon having excellent printing fastness and resolution and good high-speed followability was obtained.

Comparative Example 1 Polyether resin A, EV-40Y, carnauba wax, HNP-3, dispersant and carbon black used in Example 1 were used in the amounts shown below at a solid concentration of 25% in methyl isobutyl ketone / Disperse in a toluene = 2/1 mixed solvent to prepare a solvent-based ink. -Polyether resin A 3 parts-EV-40Y 27 parts-Carnauba wax 25 parts-HNP-3 10 parts-Dispersant 5 parts-Carbon black 30 parts By the same method as in Example 1 using this solvent-based ink. When an ink ribbon was prepared and evaluated in the same manner, the results shown in Table 1 were obtained. That is, the print was inferior in terms of print fastness and coverage of rough surface paper.

Comparative Example 2 Polyether resin A, EV-40Y, carnauba wax, dispersant and carbon black used in Example 1 were used in the amounts shown below at a solid concentration of 15% and cyclohexanone / toluene = 1/1 mixture. Disperse in a solvent to prepare a solvent-based ink. -Polyether resin A 35 parts-EV-40Y 20 parts-Carnauba wax 10 parts-Dispersant 5 parts-Carbon black 30 parts An ink ribbon was prepared in the same manner as in Example 1 using this solvent-based ink, When the same evaluation was performed, the results shown in Table 1 were obtained. That is, the high-speed followability is poor,
As a result, the ink was printed with a lot of white spots.

Comparative Example 3 Polyether resin B used in Example 2, ethylene-vinyl acetate resin "EV-410" (vinyl acetate content 19% by weight,
Mitsui DuPont Polychemical Co., Ltd.), carnauba wax, dispersant and carbon black were dispersed in methyl isobutyl ketone at a solid concentration of 25% using the amounts shown below.
Prepare a solvent-based ink. -Polyether resin B 29 parts-EV-410 13 parts-Carnauba wax 5 parts-Dispersant 3 parts-Carbon black 50 parts An ink ribbon was prepared in the same manner as in Example 1 using this solvent-based ink, When the same evaluation was performed, the results shown in Table 1 were obtained. That is, the high-speed followability is poor,
As a result, the ink was printed with a lot of white spots.

The evaluation results of Examples 1 and 2 and Comparative Examples 1 to 3 are shown in Table 1. The evaluation criteria in the table are as follows. (1) Sensitivity (high-speed followability); ◯: Ink is sufficiently transferred. Δ: Ink transfer is insufficient at the beginning of the line, and blurring occurs in printing. X: Incomplete transfer of ink is conspicuous as a whole, and patterns such as fine lines become discontinuous. (2) Resolution; ⊚: Dot reproducibility is extremely good in patterns such as halftone lines and fine lines. ◯: Dot reproducibility is good for patterns such as halftone lines and fine lines. Δ: Fading or tailing occurs in patterns such as halftone lines and thin lines. X: The print has a lot of fading and tailing, and is difficult to read. (3) Coated rough surface paper; ◯: The void ratio (white spot ratio) in the solid black print portion is less than 10%. X: The void ratio (white spot ratio) of the solid black print portion is 10% or more. (4) Printing robustness; ⊚: When one copy sheet is placed on the printed matter and a letter is written on the copy sheet with a pencil, the printed portion does not change at all. ◯: In the same test, the printed part is slightly scratched, but the ink does not set off on the copy paper. Δ: In the same test, the printed part is scratched and the ink is transferred to the copy paper. X: In the same test, the printed part is damaged, and the set-off of the ink on the copy paper occurs so that the overwritten character can be read.

[0024]

[Table 1]

Example 3 Polyether resin A used in Example 1, ethylene-vinyl acetate resin EV-410 used in Comparative Example 3, harafin wax, and carbon black were used in the amounts shown below to obtain a solid content concentration. Disperse in methyl isobutyl ketone at 20% to prepare a solvent based ink. -Polyether resin A 5 parts-EV-410 52 parts-Paraffin wax 3 parts-Carbon black 40 parts An ink ribbon was prepared in the same manner as in Example 1 using this solvent-based ink, and the same evaluation was performed. As a result, the results shown in Table 2 were obtained. That is, an ink ribbon satisfying printing fastness, resolution, and high-speed followability was obtained.

Example 4 The following blended ink containing the polyether resin A used in Example 1 and silica powder having an average particle size of 2 μ was used as a solid content concentration.
Disperse in methyl isobutyl ketone at 20% to prepare a solvent based ink. -Polyether resin A 10 parts-EV-410 42 parts-Silica powder 6 parts-Carbon black 42 parts An ink ribbon was prepared in the same manner as in Example 1 using this solvent-based ink, and the same evaluation was performed. As a result, the results shown in Table 2 were obtained. That is, an ink ribbon having satisfactory blocking resistance as well as printing fastness, resolution, and high-speed followability was obtained.

[0027]

[Table 2]

The blocking resistance "○" is 10 at 60 ° C.
It shows that the printing quality did not change from that before storage even after running test with a printer after storage for a period of time.

Claims (1)

[Claims] 1. In an ink binder, (a) 5 to 50% by weight of a polyether resin having a bisphenol skeleton in the molecule and a hydroxyl group at the molecular end, and (b) 30 to 90% by weight of an ethylene vinyl acetate resin. % (However, the content is (b) ≧
(a)), and (a) the amount of the polyether resin used is 3 to 30% by weight in the total ink composition excluding volatile components such as solvents. A thermal transfer recording medium coated on a base material via a medium.