JP2780108B2 - Thermal transfer recording medium - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a thermal transfer recording medium provided with a thermal transfer layer containing a coloring component and a binder on a substrate.

Technical Background of the Invention With the recent increase in demand for OA equipment, thermal transfer recording devices have been widely used as output devices such as facsimile machines, personal computers, and word processors.

When printing is performed using such a thermal transfer recording apparatus, a thermal transfer recording medium (ink ribbon) having a thermal transfer layer composed of a coloring component and a binder provided on a substrate is used. In a printing method using such a thermal transfer recording apparatus, a thermal head is brought into contact with a substrate side of a thermal transfer recording medium, and a heating point (dot) provided on the thermal head is formed.
By heating in accordance with the information to be output, the heat-sensitive transfer layer is melted or softened in accordance with this heating point, separated from the substrate, and transferred to the surface of a transfer medium such as paper. is there.

However, in the above method, even when printing is not performed, the thermal head is in a state of being heated to some extent, and this heat causes a part of the material having a low melting point or a low softening point contained in the thermal transfer layer. Migrates to the surface of the receiving medium in contact with the heat-sensitive transfer layer. For example, in conventional thermal transfer recording media, oil components have been added in addition to binders and pigments to improve the flexibility and transfer performance of the thermal transfer layer. However, such an oily component has been partially transferred to the surface of the transfer-receiving medium due to contact with the transfer-receiving medium, causing a so-called background stain.

In order to prevent the transfer medium from being stained, for example, Japanese Patent Application Laid-Open No. Sho 59-29196 discloses a medium in which a heat-sensitive transfer layer contains a polyhydroxy resin. This publication discloses that the properties of the OH groups of the polyhydroxy resin are used to improve the adhesion between the heat transfer layer and the substrate, and that the resin and the wax have good affinity. We use that to prevent it.

The present inventor completely differs from such a conventional method of preventing background fouling by blending a specific polyolefin in a specific amount, so that even if the thermal transfer layer contains an oily substance, the heat transfer layer may be covered with an oily substance or the like. It has been found that transfer to the transfer medium surface can be effectively prevented.

SUMMARY OF THE INVENTION The object of the present invention is to solve the problems associated with the prior art as described above, and an object of the present invention is to provide a heat-sensitive transfer recording medium in which background fouling is less likely to occur.

SUMMARY OF THE INVENTION A thermal transfer recording medium according to the present invention is a thermal transfer recording medium comprising a substrate and a thermal transfer layer provided on the substrate, wherein the thermal transfer layer forming component is measured at 135 ° C decalin. Low intrinsic molecular weight [η] is in the range of 0.01 to 0.7 dl / g, low molecular weight polybutene-1 and / or a low molecular weight copolymer having a repeating unit derived from butene-1 of 60 mol% or more, It is characterized in that it is contained in an amount of 1% by weight or more and less than 15% by weight.

As described above, the thermal transfer recording medium according to the present invention contains a specific amount of low molecular weight polybutene-1 and / or copolymer, so that background fouling can be effectively prevented.

Next, the thermal transfer recording medium of the present invention will be specifically described.

The thermal transfer recording medium of the present invention comprises a substrate and a thermal transfer layer provided on the substrate.

As the substrate used in the thermal transfer recording medium of the present invention, for example, polyethylene terephthalate, polyethylene, polycarbonate, polyimide, polyamide, polyphenylene sulfide, polysulfone, aromatic polyester, polyetheretherketone, polyethersulfone and polyether A resin film made of imide or the like can be used.

The thickness of such resin film is usually 0.8-20μ
m.

A back coat layer may be provided on the surface of the resin film where the thermal transfer layer is not formed, and various layers such as a release layer are provided on the surface on which the thermal transfer layer is applied. Is also good.

The thermal transfer recording medium of the present invention has a thermal transfer layer on such a resin film.

The thermal transfer layer is usually formed from a binder and a coloring component.

Further, the thermal transfer layer contains a low molecular weight polybutene-1 or a low molecular weight copolymer having a repeating unit derived from polybutene-1.

The polybutene-1 used here is a low molecular weight polybutene-1, and the intrinsic viscosity [η] of the polymer measured in decalin at 135 ° C. is usually 0.01 to 0.7 dl / g, preferably 0.03 to 0.7 dl / g. It is in the range of ~ 0.5dl / g.

In the present invention, butene-1 is used instead of or together with the above-mentioned polybutene-1.
A copolymer having a repeating unit derived from the following can be used.

As the copolymer used in the present invention, a copolymer having a repeating unit derived from an α-olefin in addition to a repeating unit derived from butene-1 is usually used.

Here, as the repeating unit derived from an α-olefin, a repeating unit derived from an α-olefin having 2 to 10 carbon atoms is preferable, and further from an α-olefin having 2 to 6 carbon atoms. Derived repeating units are particularly preferred (but excluding butene-1).

Such an α-olefin may be linear or may have a branch.

Specific examples of such a repeating unit derived from an α-olefin include ethylene, propylene, pentene-1, hexene-1, heptene-1, octene-1,
Nonene-1, decene-1, 3-methylpentene-1, 4
-Methylpente-1,5-methylhexene-1 and 6
And repeating units derived from -methylheptene-1. Among these, a repeating unit derived from ethylene, propylene and 4-methylpentene-1 is particularly preferred.

In such a copolymer, the repeating unit derived from butene-1 is usually at least 60 mol%, preferably at least 60 mol%.
It is contained in an amount of 75 to 100 mol%. Therefore, the repeating unit derived from an α-olefin is usually contained in the copolymer in an amount of less than 40 mol%, preferably 0 to 25 mol%.

In addition, the copolymer as described above includes butene-1 and α.
-In addition to the olefin, it may contain a repeating unit derived from another monomer in an amount that does not impair its properties, for example, 30 mol% or less.

The copolymer as described above is a low molecular weight copolymer, and the intrinsic viscosity [η] measured in decalin at 135 ° C. is as follows:
Usually, it is in the range of 0.01 to 0.7 dl / g, preferably 0.03 to 0.5 dl / g.

When the above-mentioned polybutene-1 and a copolymer having a repeating unit derived from butene-1 are used in combination, both can be used in any ratio.

In the heat-sensitive transfer recording medium of the present invention, the low-molecular-weight polybutene-1 described above is contained in the components forming the heat-sensitive transfer layer.
And / or a low molecular weight copolymer having a repeating unit derived from butene-1 is contained in an amount of 1% by weight or more and less than 15% by weight, preferably 3 to 10% by weight. ing. By setting the amount of polybutene-1 or the copolymer to 1% by weight or more, it is possible to effectively prevent background contamination on the surface of the transfer-receiving medium. 15% by weight
Even if the above-mentioned polybutene-1 or the above copolymer is blended, there is no significant improvement in the prevention of background fouling. However, when the content exceeds 15% by weight, the printing performance on a medium to be transferred having low surface smoothness tends to be improved.

The thermal transfer layer of the thermal transfer recording medium of the present invention contains a binder and a coloring component in addition to the above-mentioned polybutene-1 or a copolymer having a repeating unit derived from butene-1.

As the binder used in the present invention, a thermoplastic resin or a wax generally used as a binder for the thermal transfer layer can be used.

As the thermoplastic resin that can be used in the present invention, it is preferable to use a resin having a softening point in the range of 60 to 150 ° C. As such a thermoplastic resin, specifically, polyolefin, Polyolefin copolymer, vinyl chloride copolymer, vinylidene chloride copolymer,
Polystyrene, styrene copolymer, cumarone-indene resin, terpene resin, picolite, acrylic resin, polyacrylonitrile, acrylonitrile copolymer, diacetone acrylamide polymer, vinyl acetate, vinyl acetate copolymer, polyvinyl ether, polyamide, polyester, polyvinyl Acetal resins, polyurethane resins, cellulose derivatives, polycarbonates, ionomers, condensates of cyclic ketones and formaldehyde, condensates of m-xylene or mesitylene and formalin, rosin-modified condensates and petroleum resins . These resins can be used alone or in combination.

The thermoplastic resin is contained in the component for forming the thermal transfer layer in an amount of usually 30 to 90% by weight, preferably 40 to 70% by weight.

Further, as the wax used in the present invention,
It is preferable to use a wax having a melting point of 120 ° C. or lower.Specific examples of such a wax include animal waxes such as beeswax and ceramic wax, vegetable waxes such as carnauba wax, montan wax and the like. Petroleum waxes such as mineral waxes, paraffin wax and microcrystal wax, polyhydric alcohol esters of higher fatty acids, higher amides, higher amines, condensates of fatty acids with aliphatic or aromatic amines, and synthetic paraffins and chlorinated paraffins Synthetic waxes can be mentioned. These waxes can be used alone or in combination.

In the components forming the thermal transfer layer, the wax is
Usually, it is contained in an amount of 30 to 90% by weight, preferably 40 to 70% by weight.

 The heat-sensitive transfer layer further contains a coloring component.

As the coloring component used in the present invention, carbon black is most widely used, and in addition, red pigments or dyes, yellow dyes or pigments and blue pigments or dyes may be used alone or in combination. Can be. In the present invention, any of an organic pigment and an inorganic pigment can be used as the pigment.

In the heat-sensitive transfer layer, the coloring component as described above usually contains 5 or more components.
% By weight, preferably 10 to 40% by weight.

Further, the heat-sensitive transfer layer may contain an anti-adhesion agent so that the heat-sensitive transfer layer of the wound heat-sensitive transfer recording medium does not adhere to the back surface of the substrate contacting the heat-sensitive transfer layer. Various oils or high-boiling solvents can be blended so as to penetrate well into the medium to be transferred. In addition, additives such as a plasticizer, ceramic particles, and a stabilizer may be added.

The heat-sensitive transfer layer having such a composition can be formed, for example, by coating at least a part of the components forming the layer in a molten state (hot melt method), or dissolving or dispersing the components forming the layer in a solvent. Coating method (solvent method)
It can be formed using a known method such as

For example, when forming a heat-sensitive transfer layer by employing a hot melt method, the above-mentioned layer forming components are mixed, the mixture is heated to a temperature at which the binder is in a molten state, and then the heated mixture is formed on a substrate. Is applied and then cut into a desired shape to produce the thermal transfer recording medium of the present invention.

Further, for example, when the solvent method is employed, the above-mentioned components forming this layer are mixed with a ketone-based solvent such as methyl ethyl ketone, an alicyclic solvent such as cyclohexanone or an aromatic solvent such as toluene, or a solvent such as these. To prepare a coating solution, and apply the coating solution onto a substrate. As a method for applying such a coating liquid, known methods such as gravure coating, reverse roll coating, air knife coating, dip coating, and spinner coating can be used. After applying the coating solution on the substrate as described above, at least a part of the solvent is removed and cut into a desired shape, whereby the thermal transfer recording medium of the present invention can be manufactured.

In this case, the heat-sensitive transfer layer may be formed into a layer by applying a coating solution having a different composition two or more times, or a coating solution having a different coloring component may be repeatedly applied on the substrate at predetermined intervals. it can.

The thickness of the heat-sensitive transfer layer thus formed is a dry thickness, usually 0.5 to 20 μm, preferably 0.8 to 10 μm
It is about.

The heat-sensitive transfer recording medium of the present invention can be used by heating with a thermal head from the side of the substrate (back surface) where the heat-sensitive transfer layer is not provided, similarly to a general heat-sensitive transfer recording medium.

By blending low-molecular-weight polybutene-1 and / or a low-molecular-weight copolymer having a repeating unit derived from butene-1, a background stain is less likely to occur during printing.

Effects of the Invention In the thermal transfer recording medium according to the present invention, a low molecular weight polybutene-1 and / or a low molecular weight copolymer having a repeating unit derived from butene-1 in a component for forming a thermal transfer layer comprises: Since it is fixedly mixed, it is possible to effectively prevent background contamination on the surface of the transfer receiving medium at the time of printing.

Furthermore, by blending such a polymer or copolymer, even when a medium to be transferred having a low surface smoothness is used, bleeding around a printed character (transferred image) hardly occurs. Become.

Next, the present invention will be described in more detail with reference to Examples of the present invention. However, the present invention should not be construed as being limited by these Examples.

Example 1 A thermal transfer layer forming component having the following composition was mixed.

Thermal transfer layer forming component composition Carbon black 20% by weight Carnauba wax 20% by weight Montanic acid wax (E, manufactured by Hoechst) 40% by weight Turpentine oil 10% by weight Low molecular weight polybutene-1 ([η] = 0.2dl / g) 10% by weight A mixture having the above composition is heated and melted to uniformly disperse the carbon black. Then, the mixture is coated on polyethylene terephthalate having a thickness of 9 μm so as to have a thickness of 8 μm. This was cut to produce a thermal transfer recording medium.

The obtained heat-sensitive transfer recording medium was set in a thermal printer, and printing was performed using high-quality paper as a medium to be transferred. As a result, a clear transfer image without background contamination was obtained.

In the present invention, the intrinsic viscosity [η] is a value measured in decalin at 135 ° C.

Example 2 A heat-sensitive transfer recording medium was produced in the same manner as in Example 1, except that the composition of the heat-sensitive transfer layer forming component was changed as shown below.

Thermal transfer layer forming component composition Carbon black 20% by weight Carnauba wax 30% by weight Montanic acid wax (same as above) 40% by weight Low molecular weight polybutene-1 ([η] = 0.2dl / g) 10% by weight Thermal transfer recording obtained The medium was set in a thermal printer in the same manner as in Example 1, and printing was performed using high-quality paper as the medium to be transferred. As a result, a clear transfer image without background contamination was obtained.

Example 3 A heat-sensitive transfer recording medium was produced in the same manner as in Example 1, except that the composition of the heat-sensitive transfer layer forming component was changed as shown below.

Thermal transfer layer forming component composition Carbon black 20% by weight Carnauba wax 30% by weight Montanic acid wax (same as above) 40% by weight Turpentine oil 10% by weight Low molecular weight polybutene-1 · ethylene copolymer ([η] = 0.3dl / g) Copolymerization molar ratio = 90: 10) 10% by weight The obtained thermal transfer recording medium was set in a thermal printer in the same manner as in Example 1, and printing was performed using high-quality paper as a medium to be transferred. A clear transfer image without stain was obtained.

Comparative Example 1 A thermal transfer recording medium was produced in the same manner as in Example 1, except that the composition of the thermal transfer layer forming component was changed as shown below.

Thermal transfer layer forming component composition Carbon black 20% by weight Carnauba wax 30% by weight Montanic acid wax (same as above) 40% by weight Turpentine oil 10% by weight The obtained thermal transfer recording medium was applied to a thermal printer in the same manner as in Example 1. When the paper was set and printing was performed using high-quality paper as the medium to be transferred, bleeding was seen in the transferred image, and background smear was seen on the medium to be transferred.

Claims (1)

(57) [Claims] 1. A thermal transfer recording medium comprising a substrate and a thermal transfer layer provided on the substrate, wherein the intrinsic viscosity [η] measured in decalin at 135 ° C. in the thermal transfer layer forming component is: A low molecular weight copolymer having a low molecular weight polybutene-1 and / or a repeating unit derived from butene-1 of 60 mol% or more in the range of 0.01 to 0.7 dl / g,
A heat-sensitive transfer recording medium characterized in that it is contained in an amount of 1% by weight or more and less than 15% by weight.