JP4359738B2 - Thermal transfer recording medium - Google Patents

Description

【００５１】
【発明の効果】
本発明においては、ブロッキング防止のためにインク層の表面から粒子が突出するように配合されている感熱転写記録媒体において、該インク層の表面にエポキシ樹脂からなる表面層を設けることによって、良好な耐ブロッキング性を維持しながら、転写性、得られる印像の摩擦堅牢性がより一層改善されている。
【図面の簡単な説明】
【図１】本発明の感熱転写記録媒体の一実施例を示す概略部分断面図である。
【符号の説明】
１ 基材
２ 感熱転写インク層
３ 粒子状物質
４ 表面層
５ エポキシ樹脂粒子[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thermal transfer recording medium suitably used for forming a print image in a thermal transfer recording apparatus such as a printer or a facsimile.
[0002]
[Prior art]
Conventionally, in this type of thermal transfer recording medium, the uppermost thermal transfer ink layer is blended with particles having an average particle diameter larger than the average coating thickness of the ink layer and protrudes from the ink surface, thereby making the thermal transfer recording. It is known to prevent blocking that occurs when a medium is stored in a roll (Japanese Patent Laid-Open No. 6-15971).
[0003]
However, in the case of the above prior art, the contact area between the image receiver and the ink layer is reduced by the particles protruding from the surface of the uppermost ink layer. There is a problem in that the frictional fastness of the printed image is deteriorated along with inferior properties.
[0004]
In order to solve this problem, a thermoplastic resin solution is applied on the ink layer from which the particles in the thermal transfer recording medium protrude, and dried to provide a surface layer composed of a homogeneous layer of the thermoplastic resin. It has been proposed that the surface of the surface layer has irregularities due to the particles (Japanese Patent Laid-Open No. 11-99756).
[0005]
In this prior art, adhesiveness is exhibited even in the part of the particle protruding from the ink layer. Therefore, although transferability and frictional fastness of the image are considerably improved, it is still not sufficient and is further improved. Is desired. Moreover, there is also a problem that the blocking resistance is slightly impaired by providing the surface layer.
[0006]
[Problems to be solved by the invention]
In view of the above points, the present invention is a thermal transfer recording medium formulated so that particles protrude from the surface of an ink layer for preventing blocking, while maintaining good blocking resistance, It is an object to further improve the frictional fastness of a printed image.
[0007]
[Means for Solving the Problems]
That is, the invention according to claim 1 is directed to a thermal transfer ink layer containing an organic particulate material having an average particle size larger than the average thickness of the thermal transfer ink layer on the substrate, and further a thermosoftening surface layer thereon. In the heat- sensitive transfer recording medium in which the surface of the surface layer is uneven due to the particulate material, the surface layer has particles having a glass transition temperature of at least 30 to 59 ° C. and a glass transition temperature of the resin of 60 to The present invention relates to a thermal transfer recording medium characterized by comprising two kinds of epoxy resin particles with particles at 80 ° C.
[0008]
The invention according to claim 2 relates to the thermal transfer recording medium according to claim 1, wherein the epoxy resin particles have an average particle diameter of 0.3 to 1.5 μm.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The thermal transfer recording medium of the present invention will be described with reference to the drawings.
[0011]
FIG. 1 is a schematic partial sectional view showing an embodiment of the thermal transfer recording medium of the present invention. In FIG. 1, reference numeral 1 denotes a substrate. A thermal transfer ink layer 2 containing a particulate material 3 is provided on the substrate 1, and the particulate material 3 protrudes from the surface of the ink layer 2. A surface layer 4 made of epoxy resin particles 5 is provided on the ink layer 2, and the particulate matter 3 protruding from the ink layer 2 is covered. Concavities and convexities resulting from the particulate matter 3 protruding from the ink layer 2 are formed on the surface of the surface layer 4.
[0012]
In the present invention, a surface layer 4 made of epoxy resin particles is provided on the surface of the thermal transfer ink layer 2 from which the particulate material 3 protrudes so that the surface of the surface layer is uneven due to the particulate material 3. Concavities and convexities due to the particulate matter 3 are formed on the surface of the surface layer 4, and the surface layer 4 is composed of particles 5, so that good blocking resistance is exhibited. In addition, since the surface layer 4 is composed of the epoxy particles 5, good thermal transferability is exhibited even in the protruding part of the particulate material 3, so that the contact area having the transfer capability with respect to the image receptor is increased. Adhesive strength is improved, thereby improving transferability. Further, the friction fastness of the printed image after transfer is improved.
[0013]
Next, the present invention will be described in detail.
[0014]
The heat-sensitive transfer ink layer in the present invention comprises a heat-meltable or heat-softening vehicle, a colorant, and a particulate material.
[0015]
As the vehicle, those conventionally known can be used without particular limitation, but those mainly composed of a thermoplastic resin are preferable from the viewpoint of obtaining a high-fastness printed image. If necessary, waxes may be used in combination. Examples of the thermoplastic resin include ethylene-vinyl acetate copolymer, (meth) acrylic ester resin, vinyl chloride-vinyl acetate copolymer, polyester resin, polyamide resin, epoxy resin, acetophenone-formaldehyde resin, Examples include petroleum resins, rosin resins, and terpene resins. These resins may be used alone or in combination of two or more. Examples of the waxes include carnauba wax, candelilla wax, paraffin wax, microcrystalline wax, low molecular weight polyethylene, α-olefin-maleic anhydride copolymer wax, and the like. These waxes may be used alone or in combination of two or more.
[0016]
Examples of the colorant include carbon black and organic and inorganic color pigments and dyes generally used in this type of thermal transfer ink layer. The content of the colorant in the ink layer is suitably about 15 to 50% by weight.
[0017]
The particulate material is preferably an organic material that can maintain the particle shape even after thermal transfer . Particularly preferred particulate substances include lubricant particles such as olefin wax particles, fluorine resin particles, silicone resin particles, melamine resin particles, acrylic resin particles, phenol resin particles, and benzoguanamine resin particles. Examples of the olefin wax particles include polyethylene wax and oxidized polyethylene wax. These lubricant particles can be used alone or in admixture of two or more. Particles tend to be exposed on the surface of the printed image after transfer. In this case, it is advantageous in terms of friction fastness that the particles are slippery. The particle form of the particulate material is not particularly limited and may be indefinite, but generally spherical is preferable.
[0018]
In order to make the particulate matter protrude from the surface of the ink layer and make the surface of the surface layer uneven, it is preferable to use a material having an average particle diameter larger than the average thickness d of the ink layer. Here, the average thickness d of the ink layer refers to the average thickness of the ink layer in a portion where no particulate matter is present. The average thickness of the ink layer is suitably 1 to 3 μm from the viewpoints of transferability, image density, and scratch resistance. On the other hand, if the particle size of the particulate material is too large, the coating amount of the surface layer must be increased in order to smooth the surface state of the thermal transfer recording medium. The average particle diameter of the substance is preferably 10 times or less of the average thickness d of the ink layer, especially 6 times or less.
[0019]
Further, if the content of the particulate matter in the ink layer is too small, the blocking prevention effect is poor, and if it is too large, the transfer property is adversely affected. Therefore, the content is preferably 5 to 20% by weight, especially 5 to 15% by weight. preferable.
[0020]
A pigment dispersant, an antistatic agent, etc. can be suitably mix | blended with a heat-sensitive transfer ink layer as needed other than the said component.
[0021]
The thermal transfer ink layer is formed by dissolving the vehicle component in an appropriate solvent, and applying and drying a coating liquid containing a colorant, particulate matter, and other compounding agents as necessary, on the substrate. it can. As the solvent, a solvent that does not dissolve particulate matter is used.
[0022]
A surface layer is provided on the ink layer from which the particulate matter protrudes to cover the surface of the ink layer and the protruding particles. The surface layer is composed of thermosoftening epoxy resin particles. By using a heat-softening epoxy resin, whether the image receiver is paper or a resin film, the fixing strength to the image receiver is large, and the friction fastness of the printed image can be improved. Furthermore, the image shape can be improved by using the particle shape.
[0023]
As the epoxy resin used for the surface layer, those having good adhesiveness are preferable. Examples of such an epoxy resin include bisphenol A type, cresol novolak type, and phenol novolak type, which may be used alone. In addition, two or more kinds may be used in combination. Moreover, as an epoxy resin used for a surface layer, the thing of the range whose glass transition temperature is 30-80 degreeC is preferable. When the glass transition temperature is higher than the above range, the transferability and the adhesion to the image receiver are deteriorated. On the other hand, when the glass transition temperature is lower than the above range, blocking tends to occur.
[0024]
The epoxy resin particles used for the surface layer may be one kind of particles, but particles A having a glass transition temperature of the resin of 30 to 59 ° C. and particles B having a glass transition temperature of the resin of 60 to 80 ° C. It is preferable to be composed of two types of particles. Particles A having a glass transition temperature of 30 to 59 ° C. serve to improve transferability and adhesion to the image receptor, and particles B having a glass transition temperature of 60 to 80 ° C. serve to prevent blocking. The difference between the glass transition temperature of the resin in the particle A and the glass transition temperature of the resin in the particle B is preferably 10 ° C. or more. If this difference is less than 10 ° C., there is a tendency that the effect of the functional separation between the particles A and the particles B cannot be sufficiently improved. Moreover, it is preferable that the ratio of the particle | grains A and the particle | grains B shall be 20-80 weight% of particle | grains A and 80-20 weight% of particle | grains B with respect to the total amount of both. If the ratio of the particle A and the particle B is out of this range, there is a tendency that the effect of the functional separation between the particle A and the particle B is not sufficiently improved.
[0025]
The average particle diameter of the epoxy resin particles is preferably 0.3 to 1.5 μm. When the average particle diameter is smaller than the above range, blocking tends to occur, and when it is larger than the above range, the transferability tends to be inferior. The surface layer may be provided so as to completely cover the particles protruding from the ink layer, or there may be a portion where the particles are not partially covered. However, when the coating amount of the surface layer (referred to as the coating amount after drying, hereinafter the same) is too small, the surface state of the thermal transfer recording medium is not smoothed as much as before the surface layer is provided, and the transferability is not improved. . In this respect, the coating amount of the surface layer, 0.05 g / m ² or more, inter alia 0.1 g / m ² or more. On the other hand, if the coating amount of the surface layer is too large, the surface of the surface layer is completely flattened, which is not preferable. From this point, the coating amount of the surface layer is preferably 1.0 g / m ² or less, especially 0.5 g / m ² or less.
[0026]
The surface layer composed of the epoxy resin particles can be formed by diluting a Marshon liquid obtained by emulsifying an epoxy resin in an aqueous medium with an emulsifier or the like with an appropriate solvent as required and coating the ink layer on the ink layer. .
[0027]
In the present invention, if necessary, a release layer containing waxes as a main component may be provided between the base material and the ink layer to improve transferability.
[0028]
As the base material used in the thermal transfer recording medium of the present invention, any of various materials used as the base material of this type of thermal transfer recording medium can be used, but durability, heat transfer properties, cost From this point, a polyester film having a thickness of 1 to 6 μm, particularly a polyethylene terephthalate film is preferable. A substrate provided with a heat-resistant resin layer (stick prevention layer) on the back surface (the side on which the thermal head slides) is particularly preferred.
[0029]
【Example】
Next, the present invention will be described more specifically with reference to examples.
[0030]
Example 1
A coating solution for a release layer having the following composition is dried by bar coating on the surface opposite to the stick prevention layer of a polyethylene terephthalate film having a thickness of 4.5 μm with a stick prevention layer made of silicone resin on one side. Was 1.0 g / m ² . Next, a thermal transfer ink layer coating liquid having the following composition is applied with a gravure coater and dried to form a thermal transfer ink layer having an average thickness of 1.5 μm, and a surface layer coating liquid having the following composition is formed thereon. After drying, it was coated with a gravure coater so that the coating amount became 0.5 g / m ² and dried to form a surface layer, whereby a thermal transfer recording medium was obtained.
[0031]
Release layer coating liquid component parts by weight ester wax 8.0
Ethylene-vinyl acetate copolymer 2.0
Toluene 40.0
Isopropyl alcohol 50.0
[0032]
Ink layer coating liquid component parts by weight polyester resin (Tg 60 ° C.) 15.0
Carbon black 7.5
Toluene dispersion of oxidized polyethylene wax particles (average particle size 8 μm) (solid content concentration 10% by weight) 25.0
Methyl ethyl ketone 35.0
Toluene 17.5
[0033]
The ink layer coating solution was prepared by dissolving a polyester resin in a mixed solvent of methyl ethyl ketone and toluene, and then adding carbon black and oxidized polyethylene wax particles and dispersing them with an attritor for 2 hours.
[0034]
Surface layer coating liquid component parts by weight Bisphenol A type epoxy resin emulsion (Tg 50 ° C.) 16.0
(Average particle size 0.6 μm, solid content concentration 50% by weight)
Water 42.0
Methanol 42.0
[0035]
Example 2
In Example 1, the surface layer was formed by applying the following coating solution with a gravure coater so that the coating amount was 0.5 g / m ² after drying. A medium was made.
[0036]
Surface layer coating liquid component parts by weight Bisphenol A type epoxy resin emulsion (Tg 50 ° C.) 8.0
(Average particle size 0.6 μm, solid content concentration 50% by weight)
Bisphenol A type epoxy resin emulsion (Tg 70 ° C.) 8.0
(Average particle size 0.6 μm, solid content concentration 50% by weight)
Water 42.0
Methanol 42.0
[0037]
Comparative Example 1
In Example 1, the surface layer was formed by applying the following coating solution with a gravure coater so that the coating amount was 0.5 g / m ² after drying. A medium was made.
[0038]
Surface layer coating liquid component Part by weight acrylic resin emulsion (Tg 66 ° C.) 16.0
(Average particle size 0.1 μm, solid content concentration 50% by weight)
Water 42.0
Methanol 42.0
[0039]
Comparative Example 2
In Example 1, the surface layer was formed by applying the following coating solution (epoxy resin solution) after drying with a gravure coater so that the coating amount was 0.5 g / m ^2. Similarly, a thermal transfer recording medium was produced.
[0040]
Surface layer coating liquid component parts by weight Cresol novolac type epoxy resin (softening point 75 ° C.) 15.0
Methyl ethyl ketone 75.0
Methyl cellosolve acetate 10.0
[0041]
With respect to each of the thermal transfer recording media obtained in Examples 1-2 and Comparative Examples 1-2, the transferability, scratch resistance of the obtained printed image, and blocking resistance were evaluated by the following methods. The results are shown in Table 1.
[0042]
<Transferability>
Printing was performed under the following printing conditions using the thermal transfer recording medium, and evaluation was performed according to the following evaluation criteria.
[0043]
Printing condition printer: B-474 manufactured by Toshiba Tec Corporation
Printing pattern: Character pattern, barcode printing speed: 4 inches / second Printing energy: Standard (Printer setting value)
Printing environment: Room temperature image receptor: White PET film [0044]
Evaluation criteria A: A good image can be obtained for both the character pattern and the barcode.
B: The character pattern and the barcode are slightly blurred.
C: Significant printing blur occurs for both character patterns and barcodes.
[0045]
<Abrasion resistance>
The image obtained under the same conditions as described above was subjected to the following friction test and evaluated according to the following evaluation criteria.
[0046]
Friction tester: Lab tester manufactured by Yasuda Seiki Seisakusho Co., Ltd .: Plastic eraser load made by dragonfly Load: 500 g / cm ²
Number of times: 50 round trips [0047]
Evaluation criteria A: No change in the printed image.
B: The image can be taken without any difficulty.
C: The image can be taken considerably.
[0048]
<Blocking resistance>
Each thermal transfer recording medium (400 m in length) was wound on a molding core having an outer diameter of 25 mm with the ink surface wound inside, and allowed to stand at 50 ° C. and 85% RH for 72 hours, and then evaluated according to the following criteria.
[0049]
○: Blocking does not occur.
Δ: Blocking occurs in part.
X: Blocking occurs as a whole.
[0050]
[Table 1]

[0051]
【The invention's effect】
In the present invention, in a thermal transfer recording medium that is formulated so that particles protrude from the surface of the ink layer for blocking prevention, a surface layer made of an epoxy resin is provided on the surface of the ink layer. While maintaining blocking resistance, transferability and frictional fastness of the resulting image are further improved.
[Brief description of the drawings]
FIG. 1 is a schematic partial sectional view showing an embodiment of a thermal transfer recording medium of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Base material 2 Thermal transfer ink layer 3 Particulate matter 4 Surface layer 5 Epoxy resin particle

Claims (2)

A thermal transfer ink layer containing an organic particulate material having an average particle diameter larger than the average thickness of the thermal transfer ink layer is further formed on the substrate, and a surface layer is further laminated thereon, and the surface of the surface layer is formed by the particulate material. In the heat- sensitive transfer recording medium having irregularities, the surface layer comprises at least two types of epoxy resin particles , a particle having a glass transition temperature of 30 to 59 ° C. and a particle having a glass transition temperature of 60 to 80 ° C. A thermal transfer recording medium characterized by the above. The thermal transfer recording medium according to claim 1 , wherein the epoxy resin particles have an average particle diameter of 0.3 to 1.5 μm.

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