JP2971556B2 - Thermal transfer ink ribbon - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a thermal transfer ink ribbon. More specifically, a colored ink layer in which a heated portion is selectively softened or melted by selective heating control of a large number of heating elements provided in a heating head and transferred to a receptor is transferred to a surface of a substrate. The present invention relates to a thermal transfer ink ribbon provided.

[Problems to be Solved by Related Art] Conventionally, a thermal transfer ink ribbon of this type is provided with a colored ink layer in which a coloring agent is mixed in a vehicle mainly composed of wax, on a film-like base material. .

However, when the thermal transfer ink ribbon is used, a clear image can be obtained on paper having a smooth surface, but in the case of a receptor having a non-smooth surface such as rough paper, ink does not reach the concave portions on the surface. Therefore, there is a problem that a void or a chip is generated in the transfer ink image and a clear printed image cannot be obtained.

In order to solve this problem, attempts have been made to use a film-forming thermoplastic resin-based vehicle instead of a conventional wax-based vehicle as the vehicle for the colored ink layer in the thermal transfer ink ribbon. . By improving the film forming properties of the colored ink layer, as shown in FIG. 2, the recessed portions of the rough paper that are not reachable by the ink are bridged by the transferred colored ink layers having the film forming properties. become. FIG. 2 is a schematic diagram showing this state. In the figure, (6) is rough paper, (6a) is a convex portion, and (6b) is a concave portion. (7) is a transferred colored ink layer, which is fixed to the paper at the convex portion (6a), but forms a bridge without contacting the paper at the concave portion (6b). It has become.

By bridging the recesses in this manner, voids and chips were eliminated in the transferred ink image, and a clear printed image was obtained as if the image was transferred to a seemingly smooth receiving surface.

The technique using the ink cross-linking enables printing on not only smooth paper as in the past but also rough paper as described above, and the practicality of the thermal transfer ink ribbon has been further enhanced. .

By using a vehicle mainly composed of a film-forming thermoplastic resin for the colored ink layer as described above, a clear image can be obtained even when the receptor is rough paper. Since there is a high affinity between the plastic resin and the resin of the base material, the colored ink layer is hardly separated from the base material, and the printed image may be unclear. This phenomenon is severe especially when a high-speed printer is used.

As a countermeasure, a method of providing a release layer made of wax or the like between the base material and the colored ink layer is considered to make the colored ink layer easy to separate from the base material, but the release property of the colored ink layer is good. There is a problem in that the color ink layer is excessively transferred and an unnecessary portion of the colored ink layer is transferred to a receptor, resulting in poor print clarity.

Further, since most of the release layer is thermally transferred together with the colored ink layer, the surface of the transferred colored layer is covered with the release layer, and as a result, ink layers of different colors are overlapped like a full color transfer ink ribbon. During transfer, there is a problem that the adhesion between the ink layers is poor, and a proper superimposed image cannot be obtained.

In the present invention, in view of the above, the releasability of the colored ink layer is appropriately controlled, and even when used in a high-speed printer, a clear printed image can be formed not only on smooth paper but also on rough paper, Another object of the present invention is to provide a thermal transfer ink ribbon capable of forming an appropriate superimposed image during superimposition transfer.

[Means for Solving the Problems] The present invention provides a mold release control layer in which (1) powder particles are dispersed in a resin binder in order from the side of the substrate on the surface of the substrate, and which does not contain a surfactant. 2) a release layer mainly composed of waxes; and (3) a colorant contained in a vehicle mainly composed of a film-forming thermoplastic resin and having a viscosity of 10 ⁴ to 10 ⁸ cP at a temperature 50 ° C. higher than the softening point. A thermal transfer ink ribbon, wherein a mixed color ink layer is provided, and at least some of the powder particles penetrate the release layer and enter the color ink layer. .

[Operation and Examples] The release control layer (hereinafter, referred to as a control layer) in the thermal transfer ink ribbon of the present invention is one in which powder particles are dispersed in a resin binder, and at least one of the powder particles is dispersed. Part of the particles penetrate the release layer and penetrate the head of the colored ink layer. The particles have an anchor effect on the colored ink layer and act in a direction to control the releasability of the colored ink layer. As a result, the colored ink layer has an appropriate releasability, and a clear image can be obtained even on rough paper using a high-speed printer. The action of suppressing the releasability of the colored ink layer can be controlled by the number and size of the particles entering the colored ink layer.

Further, the thermal transfer ink ribbon of the present invention has a property that the colored ink layer is easily separated at the interface with the release layer during thermal transfer, and therefore the release layer hardly transfers. As a result, when a color image is obtained using thermal transfer inks of multiple colors, when multiple ink layers of different colors are over-transferred, proper over-transfer is achieved due to good adhesion with the ink layer that was just transferred. There is an advantage that it is done. Since the colored ink layer is made of a thermoplastic resin that has film-forming properties, the colored ink layer first transferred onto the receiving paper is cross-linked to the recesses on the rough paper due to its film-forming properties. And a clear image similar to that obtained when the image is transferred onto smooth paper is obtained. Next, when a color ink layer of another color is transferred to the same portion in a superimposed manner, since the transfer is performed on the colored layer in a cross-linked state, the influence of the rough surface is eliminated.

Thus, by using the thermal transfer ink ribbon of the present invention, a clear full-color image can be obtained even on rough paper using a high-speed printer.

Next, the present invention will be described with reference to the drawings. FIG. 1 is a partial sectional view showing one embodiment of the thermal transfer ink ribbon of the present invention. In the figure, (1) is a substrate, (2) is a release control layer,
(3) is a release layer, (4) is a colored ink layer, and (5) is powder particles added to the control layer. At least some of the powder particles (5) added to the control layer (2) are:
The head is not completely covered by the release layer (3) but protrudes into the colored ink layer (4). The particles act on the colored ink layer to control the releasability of the colored ink layer by an anchor effect.

The control layer in the present invention is formed by dispersing and mixing powder particles in a binder mainly composed of a resin.

The binder has good adhesion to the substrate, does not melt by instantaneous heating by the heating element of the heating head, and is not particularly limited as long as it has good thermal conductivity. Those having a point of 120 ° C. or higher are preferred. Usually, a polyamide resin, a polyester resin or the like composed of dimer acid and various diamines is preferably used. In addition, styrene-butadiene copolymer, polyethylene oxide, ketone resin, polyurethane resin, epoxy resin, polyacrylate resin and the like can also be used.

As the powder resin to be added to the control layer, it is necessary to use a resin having at least some of the particles that are not covered by the release layer and have a size that enters the colored ink layer. The number of particles entering the colored ink layer is preferably about 1 to 100, particularly preferably about 10 to 50 per 1 μm ² of the control layer. If the number is larger than this range, the releasability of the colored ink layer is reduced, and the printing tends to be unclear. On the other hand, if the amount is too small, the colored ink layer is easily peeled off, and the ink is easily stained on the receptor surface. The powder particles may have a certain size distribution or may have a substantially uniform particle size.
Usually, the average particle size is in the range of 0.1 to 2.0 μm, and the maximum particle size is 4 μm.
Those having about m or less are preferably used. As described above, the amount of the powder particles used may vary depending on the distribution of the particle size and the like.
The degree is preferred.

The type of the powder particles is not particularly limited. For example, inorganic or organic particles such as calcium carbonate, calcium sulfate, magnesium carbonate, amorphous silica, ultrafine acrylic resin powder, and melamine resin powder can be used.

The control layer is obtained by dissolving a binder in a solvent that does not substantially dissolve the base material, adding powder particles thereto, and thoroughly mixing and dispersing the appropriate coating means, for example, a bar coater using a wire bar, or It is formed by coating on a substrate with a gravure coater or the like. The coating amount is about 0.2 to 2.0 g / m ² as a solid, preferably about 0.4 to 1.0 g / m ² .

In the present invention, the release layer is provided on the control layer, and when the colored ink layer provided on the release layer is heated by a heating element of the heating head, the portion is received. It has the effect of making it easy to separate from the substrate side so that it can be easily transferred to the body.

The release layer is preferably mainly composed of waxes,
For example, natural waxes such as whale wax, beeswax, lanolin, carnauba wax, candelilla wax, montan wax, ceresin wax, paraffin wax,
Petroleum waxes such as microcrystalline wax,
Synthetic waxes such as oxidized wax, ester wax, low molecular weight polyethylene, and Fischer-Tropsch wax; higher fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, and behenic acid; higher fatty alcohols such as stearyl alcohol and docosanol; and sucrose Esters such as fatty acid esters of sorbitan, fatty acid esters of sorbitan, and amides such as oleylamide
Species or mixtures of two or more can be used.

The melting point of the release layer [measured by DSC (heating rate 10 ° C./min)] is about 50 to 100 ° C., preferably about 60 to 80 ° C. When the melting point is lower than the above range, the storage stability of the ink ribbon deteriorates, and when the melting point is higher than the above range, the transferability of the colored ink layer during heating deteriorates.

The release layer is a coating liquid prepared by dissolving the wax in an organic solvent, for example, methyl ethyl ketone, toluene, tetrahydrofuran, or the like, or an aqueous emulsion prepared by adding a dispersant such as a surfactant to the wax. It is formed by applying and drying by an appropriate method such as bar coating or gravure coating. The coating amount is preferably in the range of about 0.2 to 2.0 g / m ² as the amount of wax.

The colored ink layer in the present invention is a thermal transfer layer in which a portion heated by a heating element is transferred onto a receptor, and is provided on the release layer. As the vehicle, a natural or synthetic thermoplastic resin having a film-forming property is mainly used. The vehicle has a softening point of about 50 to 200 ° C., especially about 80 to 80 ° C., in order to secure transfer sensitivity and to secure a desired transfer amount of the ink and a desired crosslinking property.
Viscosity at a temperature of about 120 ° C. and 50 ° C. higher than the softening point (measured by a flow tester) is about 10 ⁴ to 10 ⁸ cP, preferably about 10 ⁴ to 10 ⁶ cP. If the softening point is lower than the above range, the storage stability of the ink ribbon is inferior, and if it exceeds the above range, the transfer sensitivity is inferior.
If the viscosity is less than the above range, the cross-linking property is poor or excessive transfer occurs, and bleeding on the printed image, crushing, tailing where the ink stain adheres to the tail behind the printed image occur. It will be easier. On the other hand, if it exceeds the above range, transfer unevenness occurs, and a void or a chip tends to be generated in the printed image, which is not preferable.

Such thermoplastic resins include, for example, ethylene polymers such as ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, styrene-butadiene copolymer, diene polymers such as polybutadiene, acrylates, One or a mixture of two or more of acrylate polymers such as methacrylate, polyamide resins, polyester resins, and polyurethane resins can be used. Since these resins have good film-forming properties even at the time of solidification, they have the feature that the image formed on the receptor has extremely excellent scratch resistance. These thermoplastic resins preferably account for 30 to 80% by weight of the total solid content of the colored ink layer coating composition.

In the case of an ink ribbon used for forming a full-color image, a glassy resin such as rosin, hydrogenated rosin, hydrogenated A rosin ester, α-pinene resin, terpene resin, coumarone indene resin, ketone resin, maleic acid resin, phenol resin and the like may be added. The amount of addition is preferably 50% by weight or less of the total solid content of the coating composition, particularly preferably about 10 to 40% by weight.

When used as a single-color thermal transfer ink ribbon as the colorant added to the colored ink layer, those conventionally used in this type of thermal transfer ink ribbon,
For example, carbon black, various organic and inorganic coloring pigments and dyes having a large covering power can be used.

When the thermal transfer ink ribbon of the present invention is used for full-color image formation, yellow, magenta,
Yellow, magenta, and cyan transparent colorants are preferably used for each of the cyan colored ink layers.

Examples of the transparent colorant that forms yellow include naphthol yellow S, Hansa yellow 5G, Hansa yellow 3G,
One or more of organic pigments such as Hansa Yellow G, Hansa Yellow GR, Hansa Yellow A, Hansa Yellow RN, Hansa Yellow R, Benzidine Yellow, Benzidine Yellow G, Benzidine Yellow GR, Permanent Yellow NCG, Quinoline Yellow Lake and dyes such as Auramine. Used.

Further, as the transparent colorant forming magenta, for example, permanent red 4R, brilliant fast scarlet, brilliant carmine BS, permanent carmine FB, lithol red, permanent red F5R, brilliant carmine 6B, pigment scarlet 3B, rhodamine lake B, rhodamine lake Y And one or more of organic pigments such as alizarin lake and dyes such as rhodamine.

Further, as the transparent colorant that forms cyan, for example, one or more organic pigments such as Victoria Blue Lake, metal-free phthalocyanine blue, phthalocyanine blue, fast sky blue, and dyes such as Victoria Blue are used.

Here, the transparent organic pigments for yellow, magenta, and cyan all refer to pigments that are transparently colored when dispersed in a vehicle.

When it is difficult to reproduce a clear black color by superimposing three colors of yellow, magenta and cyan, a black heat-sensitive transfer ink layer containing a black colorant such as carbon black or nigrosine base may be used. It may be used as the fourth layer.

The amount of the coloring agent used is about 2 to 40% by weight, especially 5 to 30% by weight of the total solid content of the coating composition for the coloring ink layer.
The degree is preferred.

Since the colored ink layer has a film-forming property, the cutting property of the edge portion of the transferred image is deteriorated at the time of transfer, and the printed image tends to lack sharpness. In such a case, it is preferable to include a fine powder having a poor affinity for the vehicle in the colored ink layer. Specifically, the average particle size is 0.1 to
Examples include silica, calcium carbonate, magnesium carbonate, aluminum hydroxide, clay, and talc having a size of about 2 μm. In the case of a full-color forming ink ribbon, a highly transparent ink ribbon is preferable. The addition amount of the fine powder is preferably about 3 to 30% by weight of the total solid content of the coating composition.

An antistatic agent, a dispersant, and the like can be added to the colored ink layer as needed.

To provide the colored ink layer, first, the thermoplastic resin, the colorant, and if necessary, the tackifier and other additives are dissolved or uniformly dispersed in an organic solvent. At this time, in order to improve the dispersion of the pigment and the like, a dispersing aid such as a fluorine-based surfactant, a higher alcohol-based surfactant, and a phosphate ester-based surfactant may be used.
The obtained coating liquid is applied on the release layer using an appropriate coating means, for example, a roll coater, a gravure coater, a reverse coater, a bar coater or the like. The coating amount is usually adjusted so that the solid content is 0.5 to 3.0 g / m ² .

As the substrate in the present invention, a polyester film, a polyamide film, and various kinds of plastic films generally used as a substrate film of this type of ink ribbon can be used. When using such a plastic film, silicone resin, fluororesin,
By providing a conventionally known stick prevention layer composed of a nitrocellulose resin, or various kinds of lubricating heat-resistant resins modified by these, or a mixture of a heat-resistant resin and a lubricant, the heating head and the It is desirable to prevent the stick phenomenon. The substrate and the stick prevention layer may contain an antistatic agent.
Further, a high-density thin paper such as a condenser paper may be used as a base material. The thickness of the base material is preferably about 1 to 9 μm, particularly preferably about 2 to 4.5 μm, from the viewpoint of improving the thermal conductivity.

In the present invention, only a single color thermal transfer layer may be formed on the same substrate, or a plurality of color thermal transfer layers may be formed on the same substrate.

As the ink ribbon for full-color transfer, usually yellow continuously on the release layer along the length direction of the base material,
A magenta and cyan colored ink layer (or a black ink layer as needed) is used repeatedly, but a yellow, magenta and cyan colored ink layer is formed on a separate base material. Is also good.

When printing is performed using the thermal transfer ink ribbon of the present invention, a clear printed image can be formed on rough paper having a Beck smoothness of about 5 to 20 seconds even in a high-speed printer. Of course, clear images can be provided on smooth paper and plastic films.

 Next, the present invention will be described with reference to examples.

Examples 1 to 5 0.1 μm on the back surface made of silicone-modified urethane resin
A control layer coating solution having the composition shown in Table 1 was applied to the surface of a 4.5 μm-thick polyethylene terephthalate film on which a stick prevention layer having a thickness of 5 μm was formed, and dried to form a control layer.

To measure the number of particles that have entered the colored ink layer, take an electron micrograph at the stage when the release agent is applied on the control layer, count the number of particles that have protruded heads within a certain area, and count the number per unit area Was calculated.

An aqueous emulsion of paraffin (melting point: 78 ° C.) was dried on the control layer and applied so that the applied amount became 1.0 g / m ² ,
After drying, a release layer was provided.

Further, a coating liquid for a colored ink layer having the composition shown in Table 2 was applied on the release layer and dried to form a colored ink layer, thereby obtaining a thermal transfer ink ribbon.

The coating liquid composition and the coating amount of the release layer and the colored ink layer are common to Examples 1 to 5.

Example 6 The same control layer and release layer as in Example 4 were provided on the same base material as in Example 4 (however, the width of the ribbon was 297 mm). A coating liquid (solid content) of 2.0 g / m ² was applied to the release layer in the longitudinal direction of the base material by applying a coating liquid of each of the yellow, magenta, and cyan colored ink layers having the compositions shown in Table 3 in order. A thermal transfer ink ribbon was obtained in which each layer was repeatedly formed in the order described above on a 297 mm substrate in the size of an A4 plate.

Comparative Example 1 A thermal transfer ink ribbon was obtained in the same manner as in Example 1 except that the control layer was not provided.

Comparative Example 2 A thermal transfer ink ribbon was obtained in the same manner as in Example 6 except that the control layer was not provided.

A print test was performed on each of the ink ribbons obtained in Examples 1 to 6 and Comparative Examples 1 and 2 using a thermal transfer printer (MTM-51, 300 DPI, manufactured by Alps Electric Co., Ltd.).
The printing speed was 50 cps, and thermal transfer paper (Beck smoothness: 600 seconds), PPC paper (Beck smoothness: 50 seconds) and bond paper (Beck smoothness: 10 seconds) were used as receivers.

In the case of the thermal transfer ink ribbon obtained in Example 6 and Comparative Example 2, the receiving paper and the yellow ink layer were overlapped,
The yellow image was transferred onto the receiving paper by the thermal head, and the receiving paper on which the yellow image was transferred was superimposed on the magenta ink layer, the magenta image was transferred in the same manner, and the cyan image was further transferred in the same manner. Transfer was performed to obtain a color image in which three color images of yellow, magenta, and cyan were superimposed.

The sharpness of the printed image obtained on the receiving paper was examined. The results are shown in Table 4.

 The measuring method and evaluation method of the sharpness are as follows.

Evaluation method of sharpness: (1) Kanji / alphabet characters are 100
The image was magnified twice, and the image was evaluated visually.

Evaluation score Very clear: 4 Clear: 3 Slightly unclear: 2 Unclear: 1 (2) From halftone (50%) printing, enlarge dot shape and observe to reproduce dot The properties were visually evaluated.

Evaluation score Very clear: 4 Clear: 3 Slightly unclear: 2 Unclear: 1 The total of the scores obtained in (1) and (2) was evaluated as sharpness.

8 points: ◎ 6-7 〃: ○ 3-5 〃: △ 2 〃: × From Table 4, it can be seen that the thermal transfer ink ribbon of the present invention gives a clear printed image and a color image even on rough paper.

[Effects of the Invention] By using the ink ribbon of the present invention, a clear monochrome or full-color image free from chipping or voids can be obtained even on rough paper in the thermal transfer punt linter.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view showing one embodiment of the thermal transfer ink ribbon of the present invention, and FIG. 2 is an explanatory diagram showing a state in which a colored ink layer is transferred so as to form a bridge on rough paper. (Main symbols in the drawings) (2): release control layer (3): release layer (4): colored ink layer (5): powder particles (6): rough paper (7): colored ink layer

──────────────────────────────────────────────────続 き Continuation of the front page (72) Koji Kiyomura, Inventor 5-4-1-14 Mundeshima, Nishiyodogawa-ku, Osaka-shi, Osaka Fuji Chemical Paper Industry Co., Ltd. Technology Center (56) References JP-A-3-140295 (JP) , A) JP-A-3-121189 (JP, A) JP-A-2-121951 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41M 5/38-5/40

Claims (1)

(57) [Claims] 1. A mold release control layer in which (1) a powdery particle is dispersed in a resin binder in order from the side of the base material, from the side of the base material, and a release control layer containing no surfactant; (3) a colored ink layer mainly composed of a film-forming thermoplastic resin and having a viscosity of 10 ⁴ to 10 ⁸ cP at a temperature 50 ° C. higher than the softening point and a colorant mixed in a vehicle; Wherein at least some of the powder particles penetrate the release layer and enter the colored ink layer.