JP3091773B2 - 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, and more particularly to a smearless type thermal transfer recording medium.

[0002]

2. Description of the Related Art Heretofore, the following examples are given as examples in which the surface roughness of a thermal transfer recording medium is specified.

A) In a heat-sensitive transfer recording medium having a constituent layer including a heat-fusible colorant layer on a support, a heat-sensitive transfer recording medium in which the surface roughness of the uppermost layer is 50 sec or less in Bekk smoothness ( JP-A-60-253589).

B) In order to form a halftone image, the surface of the ink layer is made uneven. The unevenness has a center line average roughness of 0.1 to
1.5 μm (JP-A-63-17368).
8).

C) The surface of the ink layer is rough,
It has an amplitude of 1 to 10 μm in a cycle of 0 to 30 cycles, and may contain fine particulate matter (material having a particle diameter of 1 to 20 μm, which liquefies or decreases in viscosity by heating) in the ink layer. 61-252194).

[0006] In each of the above-mentioned examples, there is a problem that white paper is generated in the image when the paper to which the image is to be transferred from the recording medium (for example, a thermal transfer ribbon) has a rough surface.

[0007] By forming the transfer layer with the heat-meltable particles,
As compared with a continuous layer, the flexibility of the transfer layer is improved, and the layer is easily cut during transfer. However, if the surface of the transfer layer has large irregularities, the area in contact with the receiving paper is reduced, and even if the layer is softened, a portion that does not come into contact with the receiving paper is generated, so that white voids occur. This is for receiving paper with low surface smoothness.
Appears prominently. Even with this low-smoothness receiving paper, in order to obtain an image without white spots, conventionally, the melt viscosity of the transfer layer was increased, the transfer layer was formed as a continuous layer, and a bridge was formed between the convex portions of the receiving paper. Was transferred to However, in this method, the melt viscosity of the transfer layer increases, and since the transfer layer is a continuous layer, the heat energy required for transfer is large and the thermal sensitivity is low.

[0008]

SUMMARY OF THE INVENTION The present invention aims to provide a thermal transfer recording medium which is excellent in thermal sensitivity, obtains a good image even on a receiving paper having a low surface smoothness, and is excellent in smearlessness of the image. is there.

[0009]

The structure of the present invention for solving the above problems is a thermal transfer recording medium as described in the claims.

[0010] The above configuration will be specifically described.
By granulating a heat-meltable material with excellent mechanical strength,
By imparting flexibility to the transfer layer and setting the center plane average roughness of the transfer layer surface to 0.1 to 0.6 μm, white spots do not occur even on receiving paper having low surface smoothness.

Further, the center surface grain size of the transfer layer surface is 85-11.
Even if it is 0 μm ² / particle, no white spots occur on the receiving paper due to low surface smoothness.

The center surface average roughness of the transfer layer surface is 0.1 μm
When the size is smaller, the transfer layer is hardly cut, and the heat insulating effect on the surface is reduced, so that the thermal sensitivity of the receiving paper having high surface smoothness is reduced.

When the thickness is larger than 0.6 μm, white voids occur in receiving paper having low surface smoothness.

When the center plane grain size of the transfer layer surface is smaller than 85, the mechanical strength of the transfer layer surface is reduced, and the transfer layer is liable to be soiled. If it is larger than 110, the unevenness on the surface of the transfer layer is small, the heat insulating effect on the surface is small, and the thermal sensitivity of the receiving paper having high surface smoothness is reduced.

The measurement of the center plane average roughness and the center plane grain size is as follows.
The measurement was performed with a three-dimensional fine shape measuring device ET-30HK (Kosaka Laboratory Co., Ltd.). The measurement of the average particle diameter was performed by LA-700 (Horiba, Ltd.).

In the case where the transfer layer is composed of a single layer, the average roughness of the center plane can be 0.1 to 0.6 μm by mainly containing particles having an average particle size of 0.5 to 1.0 μm. However, since soiling is liable to occur, it is necessary to add a binder that sufficiently binds the particles. For this reason, thermal sensitivity is reduced and white spots are easily generated in an image. Therefore, the range of the appropriate amount of binder for preventing background contamination and achieving both heat sensitivity and image quality is extremely narrow, and it is difficult to form a stable transfer layer. Therefore, the average particle size is 0.5 to 3.0 μm.
A method is preferred in which a second transfer layer mainly containing a dye and / or a pigment and a heat-fusible material is provided on the first transfer layer mainly containing particles of the above. Printing can be achieved at the same time.

A general resin can be used to bind the particles constituting the first transfer layer. However, when an image is formed, what comes to the image surface is the first transfer layer, which must be a resin that does not deteriorate smearlessness.

Therefore, for this purpose, among resins,
Unvulcanized rubber is more preferred. Examples of the unvulcanized rubber include butadiene rubber, styrene-butadiene rubber, nitrile rubber, nitrile-butadiene rubber, high styrene rubber, isoprene rubber, acrylic rubber, epichlorohydrin rubber, butyl rubber, and ethylene-propylene rubber.

The content of the binder in the first transfer layer is from 1 to
30% by weight, more preferably 3 to 20% by weight.

The second transfer layer may be composed of particles or a continuous layer. However, it is preferable that the second transfer layer contain particles of a heat-fusible material. The average particle size of the particles is 0.5 to 5 μm, and the content is preferably 1 to 30% by weight. When the transfer layer is composed of particles, the average particle diameter of the particles as the main component is preferably 0.05 to 0.70 μm.

The heat-fusible material used in the present invention preferably has a melting point or a softening point of 60 to 130 ° C. and a penetration at 25 ° C. of 2 or less as a main component. Specific examples of the wax include, but are not limited to, the following waxes.

Carnauba wax, rice wax, candelilla wax, polyethylene wax, Fischer-Tropsch wax, montan wax, hardened castor oil, montan wax derivative, paraffin wax,
Paraffin wax derivatives, microcrystalline wax, microcrystalline wax derivatives and the like.

The transfer layer may contain a water-soluble resin as a binder. Specific examples of the water-soluble resin include polyvinyl alcohol, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, polyvinylpyrrolidone, and polyacrylamide. , Starch, gelatin and the like.

In addition, various resins having a melting point or a softening point of 70 to 140 ° C. can be used as the thermoplastic resin. For example, there are an acrylic resin, a methacrylic resin, a styrene resin, a vinyl acetate resin, a vinyl chloride resin, a vinylidene chloride resin, a petroleum resin, a novolak resin, an olefin resin, a polyester resin, a polyacetal resin, and a copolymer thereof.

The particles used for the first transfer layer may be composed of a single heat-fusible material or may be composed of two or more materials.
When the particles are composed of the latter two or more heat-fusible materials,
It is preferable to use solid solution particles. As a production method, a heat-fusible material is mixed, the solid solution is heated to a heat-melted state, and the solid solution is uniformly formed by a dispersing or emulsifying means such as a sand mill, a ball mill, and a jet mill.
And get it.

The first transfer layer may be composed of a single particle or two or more different particles.

A method of applying a coating solution prepared by dissolving or dispersing components for forming the first transfer layer and the second transfer layer,
There is a method of applying an aqueous coating solution prepared by dispersing the components for forming these layers in water. In the second transfer layer, there is also a method in which a component for forming the layer is heated so that at least a part thereof is in a molten state and applied.

As the support of the thermal transfer recording medium in the present invention, various conventionally known supports can be appropriately used. Specific examples include a plastic film such as a polyester film, a polyamide film, a polyvinyl chloride film, a polyethylene ethylene film, a polypropylene film, a polyimide film, a polysulfone film, and a polycarbonate film, and a condenser paper.

The thickness of the support is preferably 2 to 15 μm in consideration of a thermal head as a heat source at the time of thermal transfer. For example, a heat source such as a laser beam capable of selectively heating a thermal transfer ink is used. There is no particular limitation in the case. When a thermal head is used, a heat-resistant protective layer made of silicon resin, silicone rubber, fluorine resin, polyimide resin, epoxy resin, phenol resin, melamine resin, nitrocellulose, etc. is provided on the surface of the support that comes into contact with the thermal head. By providing the support, the heat resistance of the support can be improved, or a substrate that could not be used conventionally can be used.

As the dyes and pigments, inorganic or organic dyes and pigments used in printing inks, paints and the like can be used. Specific examples include carbon black, disazo yellow, brilliant carmine 6B, lake red C, phthalocyanine blue, Kayaset Black KR (manufactured by Nippon Kayaku), oil yellow 3G (manufactured by Orient Chemical Co.),
Kayaset Red K-BE (manufactured by Nippon Kayaku), Kayaset Blue KFL (manufactured by Nippon Kayaku) and the like.

[0031]

The present invention will be specifically described below with reference to examples.

The following aqueous emulsion (I) for a first transfer layer was applied on a 3.5 μm polyethylene terephthalate film so as to have a dry film thickness of 2.0 μm to form a first transfer layer.

Next, an aqueous emulsion for the second transfer layer (I)
I) was applied onto the above-mentioned first transfer layer so that the dry film thickness became 2.0 μm, and a second transfer layer was formed, thereby producing a thermal transfer recording medium.

[0034]

[Table 1] The transfer layer of these thermal transfer recording media was brought into close contact with the surface of high-quality paper / mirror-coated paper, and printing was performed using a barcode printer (printing speed 150 mm / sec).
c).

The image density, thermal sensitivity, smearlessness, and white spots of the printed image were examined, and the results are shown in Table 2.

[0036]

[Table 2] (Note) Image density: Reflection density of solid printing part (by Macbeth reflection densitometer) Thermal sensitivity: Decoding rate of printed vertical barcode (parallel bar) is calculated by LASERCHECK 2811 (Symbol Technologies) It is expressed by the minimum applied energy of 90 or more.

The unit is mJ / mm ² .

Smearlessness test Friction resistance: Number of times of friction 100 reciprocations Load 100 g / cm ² -20 ° C. to 50 ° C. Good: No change Slightly bad: Ink was slightly removed from the printed portion and slightly adhered to the non-printed portion Bad: Printed portion A large amount of ink was removed, and the non-printed part was considerably attached. Scratch resistance: The transferred image was rubbed with a pen scanner to check the degree of ink removal in the printed part.

Good: No change Bad: Ink is removed and the ring breaks

[0040]

As described above, the present invention is a thermal transfer recording medium which is excellent in thermal sensitivity, obtains a good image even on a receiving paper having low surface smoothness, and is excellent in smearlessness of the image.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Nobuyuki Maeda 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Kumi Surizaki 1-3-6 Nakamagome, Ota-ku, Tokyo (56) References JP-A-2-293187 (JP, A) JP-A-63-71390 (JP, A) JP-A-63-84980 (JP, A) JP-A-60-253589 (JP, a) JP Akira 63-173688 (JP, a) JP Akira 61-252194 (JP, a) JitsuHiraku Akira 63-170251 (JP, U) (58 ) investigated the field (Int.Cl. ⁷ , DB name) B41M 5/40

Claims (4)

(57) [Claims] 1. A first transfer layer mainly composed of particles made of a heat-fusible material and a second transfer layer mainly composed of a dye and / or a pigment and a heat-fusible material are sequentially provided on a support. A thermal transfer recording medium, wherein the average roughness of the center plane of the surface of the second transfer layer is 0.1 to 0.6 μm. 2. A support having a first transfer layer mainly composed of particles made of a heat-fusible material and a second transfer layer mainly composed of a dye and / or a pigment and a heat-fusible material. In the thermal transfer recording medium, the center plane particle size of the second transfer layer surface is 85.
A thermal transfer recording medium characterized by having a particle size of about 110 μm ² / particle. 3. The thermal transfer recording medium according to claim 1, wherein the average particle diameter of the particles made of the heat-fusible material is 0.5 to 3.0 μm. 4. The thermal transfer recording medium according to claim 1, wherein the first transfer layer contains an unvulcanized rubber.