JPH0452797B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal transfer recording medium. Specifically, the present invention relates to a thermal transfer recording medium that provides a good dye transfer image even on plain paper with low surface smoothness.

[Prior Art] A thermal transfer recording medium has been conventionally used as a recording medium for transferring and forming an image on a recording sheet such as plain paper by a thermal printer, a thermal facsimile, or the like. This thermal transfer recording medium has at least one coloring material layer on a support, and the coloring material layer includes, for example, a layer containing a coloring agent made of a dye such as a pigment and a heat-fusible substance. etc. are known. In addition, films with excellent surface smoothness and dimensional stability are used as the support in order to obtain good reproducibility of the dye transfer image obtained from the color material layer coated on the support. There is.

When these conventional thermal transfer recording media print on various types of paper ranging from paper with low smoothness to paper with high smoothness, they can print well on paper with high smoothness, but they print on paper with low smoothness. ``Fading'' occurs in the line drawing area, and in the case of so-called solid black, ``white spots'' occur.
appears and becomes very difficult to see. This is a major obstacle to the widespread use of thermal printers, and a solution is urgently needed.

On the other hand, thermal transfer recording media in which a resin layer is interposed between the support and the coloring material layer are also known from JP-A-57-36698, etc.; is mainly intended for printing two or more times, and when printed on plain paper with low smoothness, ``fading'' and ``white spots'' occur as described above.

[Problems to be Solved by the Invention] The present invention has been made in view of the above circumstances, and it is possible to perform good printing in a wide smoothness range from paper with high smoothness to paper with low smoothness. The technical challenge is to

[Means for Solving the Problems] A thermal transfer recording medium of the present invention for solving the above-mentioned technical problem is a thermal transfer recording medium in which a heat-melting coloring material layer is laminated on a support. Young's modulus is 1.0× at 50℃ between the heat-melting coloring material layer
It is characterized by interposing a rubber-based resin layer with a thickness of 10 ⁸ Nm ^-2 or less.

The present invention will be described in further detail below.

The resin layer in the thermal transfer recording medium of the present invention is
The main component is rubber resin.

As a rubber-based resin, Young's modulus is 1.0× at 50℃.
10 ⁸ Nm ^-2 or less is used, preferably 1.0
×10 ⁷ Nm ^-2 or less.

Specifically, natural rubber, cyclized rubber, polyisoprene, and styrene-butadiene copolymer are preferred.

The thickness of the rubber resin layer of the present invention is 0.5 to 5 μm,
Preferably 0.7 to 3 μm, more preferably 0.9 to 2 μm
It is.

The resin layer of the present invention may contain resins other than rubber-based resins, and any resin may be used as long as it has adhesion to the support and the coloring material layer.
Polyvinyl butyral resins, ethylene-ethyl acrylate resins, ethylene-vinyl acetate resins, epoxy resins, etc. generally give good results.

The rubber resin of the present invention has a resin layer with a resin component of 100%
50 to 100 parts by weight, more preferably
It is preferable to add 60 to 100 parts by weight.

The method of incorporating the rubber-based resin layer of the present invention into the resin layer is arbitrary.

The heat-melting coloring material layer in the present invention mainly consists of a low-melting point substance, a coloring agent, and a softening agent. As the low-melting point substance, a known heat-melting substance may be used without any particular restriction, but a hard wax may be used. It is preferable to use a combination of at least one type of soft wax and at least one type of soft wax.

The hard wax used in the present invention is 25℃ (100℃
Waxes having a penetration degree of less than 8 in g). Measurement of penetration is based on JIS K 2530. A substance with a melting point (measured by Yanagimoto MPJ-2 type) of 50 to 100°C is preferable. Specific examples of hard waxes used in the present invention include ester waxes (natural ester waxes such as carnauba wax and Montan wax, and Hoechst waxes).
Hoechst Wax E, F, KP, KPS, BJ, OP,
synthetic ester waxes such as OM, X22, U and O), oxidized waxes (paraffin waxes,
Wax obtained by oxidizing wax such as microcrystalline wax, NPS manufactured by Nippon Seiro Co., Ltd.
-9210, NPS-6115, manufactured by Toyo Petrolite Co., Ltd.
PETRONABA・C, CARDIS 314, etc.), low molecular weight polyethylene wax (especially molecular weight 300~
1000, manufactured by Toyo Petrolite Co., Ltd.
POLYWAX 500 and 655, etc.), acid waxes (Hoechst Wax S and LP, etc. manufactured by Hoechst), and the like.

On the other hand, the soft wax used in the present invention is heated at 25°C.
(100g) is a wax with a penetration rate of 8 or higher. A substance with a melting point (measured by Yanagimoto MPJ-2 type) of 50 to 100°C is preferable. A specific example of the soft wax used in the present invention is microcrystalline wax (Nisseki Micro Wax).
155, 180 (manufactured by Nippon Oil Co., Ltd.), HI-MIC-1080,
HI-MIC-2065, HI-MIC-2095, HI-MIC-
1070, HI-MIC-1045, HI-MIC-2045 (manufactured by Nippon Seirosha), STAR WAX 100, BE SQUARE
175, 185, VICTORY, ULTRAFLEX (manufactured by Toyo Petrolite, etc.), stearic acid, behenic acid,
Examples include stearyl alcohol, white wax, beeswax, dodecyl stearate, stearone, sorbitan monostearate, and polyoxyethylene monostearate. In addition, when hard wax and soft wax are used together, the composition ratio is 1:9 to 9:1, more preferably 2:8 to 8:2.
That's fine.

The coloring agent used in the present invention may be appropriately selected from conventionally known pigments, such as direct dyes, acid dyes, basic dyes, disperse dyes, oil-soluble dyes (including metal-containing oil-soluble dyes), etc. You can choose from among them. The coloring matter used in the coloring material layer of the present invention may be any pigment that can be transferred (transferred) together with the heat-melting substance, and may be a pigment in addition to the above. In addition, specifically, the following can be mentioned. In other words, the yellow pigment is Kayalon Polyester Light Yellow.
5G-S (Nippon Kayaku), Oil Yellow S-7 (white clay), Eisenspiron GRH Special (Hodogaya), Sumiplast Yellow FG (Sumitomo), Eisenspiron Yellow GRH (Hodogaya), etc. are preferably used. It will be done. Red dyes include Diaceriton Fastred R (Mitsubishi Kasei), Dianics Brilliant Red BS-E (Mitsubishi Kasei), Sumiplast Stretch FB (Sumitomo), Sumiplast Stretch HFG (Sumitomo), and Kayalon. Polyester Pink RCL-E (Nippon Kayaku), Eisen Spiron Red GEH Special (Hodogaya), etc. are preferably used. As blue pigments, Diaceritone Fast Brilliant Blue R (Mitsubishi Kasei), Dianics Blue EB-
E (Mitsubishi Kasei), Kayalon Polyester Blue B-
SF Conch (Nippon Kayaku), Sumiplast Blue 3R
(Sumitomo), Sumiplast Blue G (Sumitomo), etc. are preferably used. In addition, as yellow pigments, Hansa Yellow 3G, Tartrazine Lake, etc. are used.
As a red pigment, brilliant carmine FB-
Piure (Sanyo pigment), brilliant carmine 6B
(Sanyo Shiki), Alizarin Lake, etc. are used. As blue pigments, Cerulean Blue, Sumikaprint Cyanine Blue GN-O (Sumitomo), Phthalocyanine Blue, etc. are used. As black pigments, Carbon Black, Oil Black, etc. are used. used.

The colorant contained in the coloring material layer of the present invention is preferably a non-sublimable colorant, and as a non-sublimable colorant, it is transferred together with a heat-fusible substance to a recording sheet such as plain paper during heating recording. Any non-sublimable substance that can be used and has a color may be used. It may be a substance that absorbs light at visible wavelengths (400 nm to 800 nm) or a substance that forms a substance that absorbs in the visible light range, and is generally referred to as a dye, and is used as a thermal transfer recording medium. suitable for Among synthetic pigments called dyes and pigments, natural pigments called animal pigments or vegetable pigments, non-sublimable ones are used. Non-sublimable colorants preferably used in the present invention are colorants excluding sublimable (including those that vaporize with melting or dissolution) used in mordant dyes and the like.

Basic dyes preferably used as colorants in the present invention include, for example, crystal violet (C.
I.42555), malachite green (CI42000), methyl violet (CI42535), Victoria blue (CI44045), triphenylmethane dyes such as Mazienta (CI42510), auramine CI655)
Diphenylmethane dyes such as Astraphloxin FF (CI48070), Eisenkathylon Yellow
3GLH (Hodogaya Chemical Industry Co., Ltd. product, CI48055), Eisenkatilon Red 6BH (CI48020), Astrazone Golden Yellow GL (Bayer Co., Ltd. product, C.
I.48054), methine and azamethine dyes,
Rhodamine B (CI45170), Rhodamine 6G (C.
Xanthene dyes such as I.45160), Astrazone Blue GL (CI11052), Astrazone Red
Thiazole azo and triazole azo dyes such as F3BL (CI11055), Eisencathilone Blue
5GH (CI11085), methylene blue (CI52015)
Quinoneimine dyes such as Eisencathilone Red GTLH (CI11085), Cevron Yellow 3RL (DuPont product, CI11087), Astrazone Blue
Examples include insulating azo dyes and anthraquinone dyes having an onium group at the structural end, such as FGL (CI61512).

Examples of oil-soluble metal complex dyes include symmetrical 1:2 type azo metal complex dyes, asymmetrical 1:2 type azo metal complex dyes, 1:1 type azo metal complex dyes, azomethine metal complex dyes, and formazan type metal complex dyes. Examples include metal complex dyes, metal phthalocyanine dyes, and organic base salts of these dyes. Specifically, Eisenspiron Yellow 3RH (Hodogaya Chemical Co. product, CI Solvent Yellow 25), Zapon Fast Yellow R (BASF product, CI18690), Eisenspiron Orange 2RH (CI Solvent Orange 40), Zapon Fast Scarlet B (C.
I.12783), Eisenspiron Red GEH (CI Solvent Red 84), Zaponphastrone BE
(CI12715), Zapon Fast Violet BE (C.
I.12196), Cyanine Blue BB (Sumitomo Chemical Co., Ltd. product,
CI74160), Variable Asto Black #3804 (Orient Chemical Company product, CI12195), Eisenspiron Yellow 3RH Special (CI Solvent Yellow 25:1), Eisenspiron Orange 2RH Special (CI Solvent Orange 40:1), Eisenspiron Blue 2BNH (CI Solvent Blue 117), Zapon Fuasto Blue HFL (C.
I.74350), Eisenspiron Black BH Special (CI Solvent Black 22:1), etc.

Acidic dyes such as CI Acid Yellow
19, CI Assisted Red 37, CI Assisted Blue
62, CI Acid Orange 10, CI Acid Blue 83, CI Acid Black 01, etc.

Direct dyes are CI Direct Yellow 44, CI
Direct Yellow 142, CI Direct Yellow 12, CI Direct Blue 15, CI Direct Blue 25, CI Direct Blue 249, CI Direct Red 81, CI Direct Red 9, CI Direct Red 31, CI Direct Black 154,
Examples include CI Direct Black 17.

The disperse dyes are CI Dispose Yellow 5, C.
I. Dispose Yellow 51, CI Dispose Yellow 64, CI Dispose Red 43, CI Dispose Red 54, CI Dispose Red 135,
Examples include CI Dayspose Blue 56, CI Dayspose Blue 73, and CI Dayspose 91.

The ballasted dyes used in the present invention are dyes having at least one ballast group in the dye matrix, such as azo dyes, azomethine dyes, anthraquinone dyes, naphthoquinone dyes, sterine dyes, quinophthalo dyes, and phthalocyanine dyes. Ballast groups are groups that are highly soluble in heat-melting substances, such as alkyl groups, cycloalkyl groups, aralkyl groups, alkoxy groups, alkylsulfonylamino groups, alkylsulfonyl groups, hydroxylalkyl groups, cyanoalkyl groups, alkoxycarbonylalkyl groups,
It is a group having an alkyl group having 6 or more carbon atoms, such as an alkoxyalkyl group and an alkylthio group, or an alkylene group. In particular, a ballast group having at least one alkyl group having 6 or more carbon atoms in the molecule is preferred. As an example of the structure of the ballasted dye preferably used in the present invention,
Examples include those described in patent application (A) filed on the 25th, but the present invention is not limited thereto.

The softener used in the present invention includes a low softening point polymer selected from ethylene-ethyl acrylate resin, ethylene-vinyl acetate resin, etc., preferably one having a softening point (measured value by ring and ball method) of 40 to 90°C. It will be done.

The composition ratio of the coloring material layer in the present invention is 50 to 95% (by weight, same below) (more preferably 70 to 95%) of a low melting point substance, 5 to 20% of a coloring agent, and 0 to 95% of a softener.
30% (more preferably 0 to 10%) is good.

Note that the support used in the thermal transfer recording medium of the present invention is preferably a support that has heat-resistant strength, high dimensional stability, and high surface smoothness. Materials include, for example, papers such as plain paper, condenser paper, laminated paper, coated paper, resin films such as polyethylene, polyethylene terephthalate, polystyrene, polypropylene, polyimide, paper-resin film composites, aluminum foil, etc. Metal sheets and the like are preferably used. The thickness of the support is usually approximately
It is preferably 60 μm or less, particularly 2 to 20 μm.
Furthermore, in the thermal transfer recording medium of the present invention, the structure on the back side of the support may be optional, and a backing layer such as a sticking prevention layer may be provided.

In the thermal transfer recording medium of the present invention, a technique suitable for coating a rubber resin layer on a support such as a polymer film and a technique suitable for coating a heat-melting coloring material layer on a rubber resin layer are used. Techniques are known in the art and these techniques can also be used in the present invention. For example, the rubber resin layer (and the heat-melting color material layer) can be formed by hot-melt coating the composition, or by solvent coating a coating solution obtained by dissolving or dispersing the composition in an appropriate solvent. It is a layer. As a coating method for the rubber resin layer (and heat-fusible colorant layer) of the present invention, any known technique can be employed, such as a reverse roll coater method, an extrusion coater method, a gravure coater method, and a wire bar coating method. The heat-melting coloring material layer of the present invention may have a thickness of 20 μm or less, more preferably 1 to 15 μm.

The thermal transfer recording medium of the present invention may contain highly thermally conductive fine powder in its constituent layers or in its support. The high thermal conductivity fine powder has a higher thermal conductivity than the above-mentioned resin (for example, thermal conductivity of 6.0×
10 ^-4 ~25.0×10 ^-4 cal/sec・cm・℃) and has a high melting point. Many metals such as aluminum and copper are possible, and tin oxide, aluminum oxide, magnesium oxide, etc. Oxides of titanium and nitrides such as titanium nitride can also be used. The particle size of the high thermal conductivity fine powder of the present invention is preferably 3 μm or less, more preferably 0.01 to 1 μm. For example, when it is contained in the rubber-based resin layer of the present invention, the mixing ratio of the resin and the fine powder is preferably such that the volume fraction of the fine powder is 10 to 90%, more preferably 20 to 60%.

The highly thermally conductive fine powder is preferably dispersed and contained in the rubber-based resin layer, but may also be contained in the support and/or the colorant layer.

The heat-sensitive transfer recording medium of the present invention may have other constituent layers such as an undercoat layer (for example, a layer for improving film adhesion) and an overcoat layer (for example, a layer made of a heat-melting substance). good.

[Function] The thermal transfer recording medium of the present invention can be recorded (printed) on a recording sheet such as plain paper by the same method as known thermal transfer recording media. For example, the coloring material layer is dissolved when heated with a thermal head. However, by effectively transferring this dissolved coloring material layer to the recording sheet, which is the transfer medium, using the rubber elasticity of the rubber-based resin layer, it is possible to perform good printing even on paper with low smoothness. Become.

[Effects of the Invention] According to the present invention, in a heat-sensitive transfer recording medium in which a heat-melting coloring material layer is laminated on a support, a rubber-based resin layer is interposed between the support and the heat-melting coloring material layer. With this configuration, the above-mentioned technical problem of the present invention can be solved by the simple means of using a rubber-based resin.

[Example] Examples are given below, but the embodiments of the present invention are not limited thereto. Note that "parts" used below indicate "parts by weight."

Example 1 Using a wire bar on a 5.3 μm thick polyethylene terephthalate film, the dry film thickness was 1 μm.
A coating liquid having the following composition was applied to obtain a rubber-based resin layer.

Rubber resin layer coating liquid Polybutadiene (JSR RB810 manufactured by Japan Synthetic Rubber Co., Ltd.) [8.0×10 ⁶ Nm ^-2 (50℃)] 10 parts Toluene 200 parts After drying, apply the following coloring material layer coating liquid using a wire bar. After coating to a dry film thickness of 3 μm, the sample was heated at 60° C. in a dryer for 20 minutes to obtain a thermal transfer recording medium sample of the present invention.

Colorant layer coating liquid carbon black 10 parts Microcrystalline wax (Micro UHF manufactured by BARECO) 20 parts Montan wax (manufactured by Kato Yoko Co., Ltd.) 20 parts ethylene-ethyl acrylate resin (NUC-6070 manufactured by Nippon Unicar Co., Ltd.) 2 parts Toluene 120 copies Using this thermal transfer recording medium sample, the applied power per heating element was 0.6W using a thermal printer (prototype machine equipped with a thin film type line thermal head with a heating element density of 8 dots/mm). Recording was performed by giving 1 millisecond of energy. Bond paper (Beck smoothness 12) is used as transfer paper.
seconds) was used. As a result, line drawings appear blurry.
Clear printing was obtained with no "white spots" occurring in solid black areas.

Comparative Example 1 In Example 1, only a heat-fusible coloring material layer having the same composition as above was coated and heated in a dryer at 60° C. for 20 minutes to obtain a comparative thermal transfer recording medium sample. The dry film thickness was 3 μm. This sample was used in Example 1.
Printing was carried out using the same thermal printer as above and using bond paper (Beck smoothness: 12 seconds).
As a result, ``fading'' occurred in line drawings, and ``white spots'' appeared in solid black areas, resulting in prints that were extremely difficult to read.

Comparative Example 2 A comparative thermal transfer recording medium sample was obtained in the same manner as in Example 1 except that polyvinyl butyral was used instead of polybutadiene. The dry film thickness of the resin layer was 1 μm. This sample was printed in the same manner as in Example 1, but the line drawings were "fainted".
This resulted in ``white spots'' appearing in solid black areas, resulting in prints that were extremely difficult to read.

Claims (1)

[Claims] 1. In a heat-sensitive transfer recording medium in which a heat-fusible coloring material layer is laminated on a support, a rubber having a Young's modulus of 1.0×10 ⁸ Nm ^-2 or less at 50° C. is placed between the support and the heat-melting coloring material layer. A heat-sensitive transfer recording medium characterized by having a resin layer interposed therebetween.