JPS63183882A - Thermal transfer recording medium - Google Patents

Abstract

PURPOSE:To enable a good quality-transfer even to a low-surface smoothness paper to be subjected to transfer and to enhance a printing quality, by a method wherein an ionomer is contained in at least one of heat-softening layers. CONSTITUTION:A heat-softening layer is a layer containing a hot-melt substance and a thermoplastic resin, while the characteristics of the layer depends dominantly on the attribute of the thermoplastic resin in the aforesaid two components. The heat-softening layer contains an ionomer. The ionomer is an ethylene copolymer containing carboxyl group wherein a metal ionic bond is introduced between the polymer main chains by an alkali metal or an alkali earth metal. As the ethylene copolymer containing carboxyl group, for example, a copolymer of an ethylene with an acrylic acid, a methacrylic acid, or the like is used. The ionomer is produced in such a manner as; the ethylene and the metacrylic acid are copolymerized and crosslinked with Mg ion. The content of the ionomer in the hot-melt layer is preferably 5-50 wt.%, and that of 10-30 wt.% is especially preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal transfer recording medium. For more details,
The present invention relates to a thermal transfer recording medium that can form high-quality prints even on transfer media with low surface smoothness.

[Background of the Invention] A thermal transfer recording medium (thermal transfer ink ribbon) is usually
A state in which a heat-sensitive transfer recording medium having a heat-fusible ink layer formed by dispersing a colorant in a heat-fusible substance on a sheet-like support is used, and the ink layer is superimposed on a transfer medium (generally paper). The support side of the thermal transfer recording medium is heated by a thermal head, and the molten ink layer is transferred to the transfer medium, thereby forming an ink image corresponding to the heated portion of the thermal head.

However, this method using a thermal transfer recording medium has a problem in that the print quality is affected by the surface smoothness of the transfer medium. That is, although good printing is performed on a transfer medium with high smoothness, when a transfer medium with low smoothness is used, the print quality is significantly degraded.

These three points are particularly problematic when using paper, which is the most typical transfer medium. In other words, paper with high smoothness is rather special, and ordinary paper has
Its surface has considerable irregularities. For example, in rough vapor with Bekk smoothness of about 10 seconds,
There are many parts of the surface where the depth from the top of the convex part to the deepest part of the concave part is IOpm or more. When thermal transfer printing is performed using such paper, the print quality is greatly deteriorated due to low print density or parts of the print being missing.

Moreover, in today's world, where printing speeds are increasing due to advances in thermal recording devices, it is not enough for thermal transfer recording media to achieve good print quality on transfer paper with low surface smoothness; There is an ever-increasing demand for thermal transfer recording media that require only a small amount of heat to be supplied from the head, that is, thermal transfer recording media that have high sensitivity and excellent high-speed compatibility.

Under these circumstances, attempts have been made to make thermal transfer recording media multilayered in order to improve the print quality on transfer paper with low surface smoothness.

As such an attempt, 4. ¥ Opening/closing 59-224392
No. 60-97888, No. 60-18759:1, No. 6G-18:1192 and No. 60-18548
There are inventions described in various publications such as No. 8, but when adopting a layer structure of two or more layers like these, it is difficult to put it into practical use with the same design concept as in the case of a conventional single layer structure, and therefore,
It is difficult to say that a thermal transfer recording medium that provides sufficiently good printing quality against rough vapor has yet been realized.

[Purpose of the invention] The present invention has been made based on the above circumstances.

That is, an object of the present invention is to provide a thermal transfer recording medium that can realize high-quality printing not only on transfer media with excellent surface smoothness but also on transfer media with poor surface smoothness. It is to be.

[Means for achieving the above purpose] The structure of the present invention is to achieve the above object.

At least one release layer is laminated on the support, and at least one heat-softening layer is laminated on the release layer, and the! 11
A thermal transfer recording medium containing a colorant in at least one of a delamination layer and a heat-softening layer, characterized in that at least one heat-softening layer contains an ionomer.

The thermal transfer recording medium of the present invention has at least one release layer on a support and at least one heat-softening layer on the release layer. A release layer and a thermosoftening layer are laminated in this order on top. For example, as a layer structure, a release layer, a first heat-softening layer, a second heat-softening layer, etc. may be laminated in this order on the support;
Delamination, first thermosoftening layer, second peeling layer, second thermosoftening layer
It may be a multi-layered structure in which release layers and thermosoftening layers are alternately laminated as shown in ....In this case, at least one of the thermosoftening layers must contain an ionomer. If necessary, it is preferred that this layer comprises the top layer, and it is particularly preferred that all thermosoftenable layers comprise the ionomer. By doing so, the print quality tends to improve.

Further, the colorant may be contained in either the release layer or the heat-softening layer, but in the present invention, it is particularly preferable that the colorant is contained in the heat-softening layer.

However, in the present invention, an embodiment in which a release layer and a heat-softening layer are laminated in this order on a support is most preferable, and the thermal transfer recording medium of the present invention will be described below with a focus on this embodiment.

-Support 1 The support used in the thermal transfer recording medium of the present invention is desirably one that has heat-resistant strength, high one-dimensional stability, and high surface smoothness.

The materials include, for example, papers such as plain paper, condenser paper, laminated paper, and coated paper, resin films such as polyethylene, polyethylene terephthalate, polystyrene, polypropylene, and polyimide, composites of paper and resin films, and aluminum foil. Metal sheets such as the above can be suitably used.

The thickness of the support should be adjusted to obtain good thermal conductivity.

In normal cases, it is preferably 60 gm or less, particularly 1.5 to 1
It is within the range of 5 μm.

In the thermal transfer recording medium of the present invention, the structure on the back side of the support is arbitrary, and an eight-sticking layer such as an anti-sticking layer may be provided.

-Release layer- The release layer is a layer in which properties of a heat-melting substance are dominant, and may contain a thermoplastic resin.

Here, the release layer adjacent to the support plays a role in adjusting the adhesive force between the thermosoftening layer and the support.

In other words, the release layer maintains the mechanical properties of the entire heat-softening layer, such as film adhesion to the support and film strength, and also maintains the mechanical properties of the heat-softenable layer, such as film strength and film strength, when the heat-softenable layer is separated from the support by heating. The softening layer acts to quickly peel off and transfer from the thermal transfer recording medium to the transfer paper.

As for the heat-melting substance and thermoplastic resin used in this release layer, the same ones as those used in the heat-softening layer described below (excluding emulsion polymers) can be used. Each component will be described later.

Preferable heat-melting substances used in the release layer include Wausses having a melting point of 40 to 150°C.

Preferred thermoplastic resins include acrylic resins and ethylene copolymers.

The content of the heat-fusible substance in the release layer is usually set at 50% by weight or more, particularly preferably from 60 to 97% by weight.

The content of the thermoplastic resin is usually less than 50% by weight, preferably 3 to 40% by weight, particularly preferably 5 to 40% by weight.

This release layer usually does not contain colorants. However, it is also possible to contain a part of the colorant, and in this case, the amount is usually 40% by weight or less of the colorant used in the thermal transfer recording medium of the present invention.

In addition, inorganic or organic fine particles (metal powder, silica gel, etc.) or oils (linseed oil, mineral oil, etc.) can also be added.

The thickness of the 'Agi layer is usually 0.5 to 4 mm, preferably 1.0 to 2.5 mm.

The viscosity of the release layer is preferably 2 to 1000 cps at 100°C.

In coating the release layer on the support, it is preferable to employ a hot melt coating method.

The hot-melt coating method involves mixing a heat-melting substance and optionally added thermoplastic resin and coloring agent.
This is a method in which the resulting mixture is heated to melt a heat-fusible substance or the like and coated onto a support. When a hot melt coating method is employed, it is sufficient that at least the meltable substance is in a molten state, and the heating temperature is usually 150°C or less. In this case, the molten component can be applied by a known method such as a coating method using a wire bar.

In addition to the hot-melt coating properties, the release layer can also be applied by preparing an aqueous emulsion that forms this layer and applying it, or by dissolving or dispersing the components forming this layer in an organic solvent and applying it. It is also possible to prepare by adopting.

- Thermo-softening layer - The thermo-softening layer is a layer containing a heat-melting substance and a thermoplastic resin, and among both components, the attributes of the thermoplastic resin are dominant.

And in the thermal transfer recording medium of the present invention.

The thermosoftening layer contains an ionomer.

Here, the ionomer is a copolymer of ethylene containing a carboxyl group, in which a metal ion bond is introduced between the main chains of the polymer using an alkali metal or an alkaline earth metal.

Examples of copolymers of ethylene containing carboxyl groups include copolymers of ethylene and acrylic acid, methacrylic acid, and the like.

The method for producing this ionomer is already known, and can be obtained, for example, by copolymerizing ethylene with meth or acrylic acid and crosslinking with Mg ions.

In the present invention, the ionomer is used as an aqueous emulsion.

The content ratio of the ionomer in the thermosoftening layer is 5 to 5.
50% by weight is preferred, particularly 10-30% by weight.

8 Plastic resins include polyamide resin, polyester resin, polyurethane resin, polyolefin resin, acrylic resin, vinyl chloride resin, cellulose resin, rosin resin, petroleum resin, natural rubber, styrene butadiene. Elastomers such as rubber, isoprene rubber, chloroprene rubber, ester gum, rosin maleic resin, rosin phenol resin, hydrogenated rosin and other rosin conductors: phenolic resin, terpene resin, cyclopentadiene resin, aromatic hydrocarbons Softening point of resin etc. 50-150
It is possible to list polymeric compounds at °C.

More preferred thermoplastic resins include acrylic resins.

The acrylic resin is obtained by emulsion polymerization of a monobasic carboxylic acid such as acrylic acid or methacrylic acid or an ester thereof, and at least one copolymerizable hetamine. Examples of carboxylic acid monomers include methyl, ethyl, isopropyl, butyl, isobutyl, amyl, hexyl, octyl, 2-ethylhexyl, decyl, dodecyl, hydroxyethyl, and hydroxyethyl esters of acrylic acid or methacrylic acid.

Monomers that can be copolymerized include vinyl acetate, vinyl chloride, vinylidene chloride, maleic anhydride, fumaric anhydride, styrene, 2-methylstyrene, chlorostyrene,
Acrylonitrile, vinyltoluene, N-methylol acrylamide, N-methylol methacrylamide, N-
Examples include butoxymethylacrylamide, N-butoxymethacrylamide, vinylpyridine, and N-vinylpyrrolidone, and one or more of these may be selected.

As the thermoplastic resin, diene copolymers are also preferable, and emulsion polymers of diene yarn polymers such as butadiene, isoprene, isobutylene, and chloroprene and the above-mentioned copolymerizable heptamers, such as butadiene, styrene, butadiene, etc. Examples include styrene-vinylpyridine, butadiene-acrylonitrile, chloroprene-styrene, chloroprene-acrylonitrile, and the like.

Further, more preferable thermoplastic resins include ethylene copolymers, such as ethylene-vinyl acetate, ethylene-ethyl acrylate, ethylene-methyl methacrylate,
Copolymers such as ethylene-isobutyl acrylate, ethylene-acrylic acid, ethylene-vinyl alcohol, ethylene-vinyl chloride, and ethylene-acrylic acid metal salts can be mentioned.

As the heat-melting substance, it is preferable to use a solid or semi-solid substance having a melting point (measured value using Yanagimoto PJ-2 type) of 40 to 150°C.

Specific examples include vegetable waxes such as carnauba wax, wood wax, auriculie wax, and Nispar wax; animal waxes such as beeswax, insect wax, shellac wax, spermaceti wax; paraffin wax, microcrystalline wax, polyethylene wax, and ester wax; Waxes such as stone oil waxes such as acid waxes, mineral waxes such as montan wax, osichelite, and ceresin; higher fatty acids such as palmitic acid, stearic acid, margaric acid, and behenic acid; valmityl alcohol, stearyl alcohol, behenyl alcohol, marganyl Higher alcohols such as alcohol, myricyl alcohol, and eicosanol; Higher fatty acid esters such as cetyl palmitate, myricyl palmitate, cetyl stearate, and myricyl stearate; acetamide, propionic acid amide, palmitic acid amide, stearic acid amide, amide wax, etc. Amides include higher amines such as stearylamine, behenylamine, and palmitylamine, which may be used alone or in combination.

Among these various heat-melting substances, the melting point is 40 to 15
Waxes at 0°C are preferred.

The content ratio of the thermoplastic material and the thermoplastic resin in the thermosoftening layer is determined based on the type and characteristics of the thermoplastic resin and thermoplastic material used, so that the properties of this layer are controlled by the attributes of the thermoplastic resin. It can be set appropriately taking into consideration.

However, since the main function of this thermoplastic resin during use is to fix the colorant on the transfer medium, in order to ensure this function, the total amount of the components forming this layer (however, the colorant It is preferable that the thermoplastic resin be contained in an amount of 50% by weight or more based on the weight of the thermoplastic resin (excluding the above).

This heat-softening layer usually contains a colorant. In the present invention, a common colorant can be used as the colorant. The colorant most widely used in thermal transfer recording media is carbon black, and carbon black, which is commonly used, can also be used in the present invention.

However, in the present invention, pigments and dyes such as inorganic pigments and organic pigments can be used in addition to carbon black.

Examples of the inorganic pigments include titanium dioxide, zinc oxide, Prussian true, cadmium sulfide, iron oxide, and chromates of lead, zinc, barium, and calcium.

Examples of the organic pigments include azo-based, thioindigo-based, anthraquinone-based, anthanthrone-based, and triphenedioxazine-based pigments, vat dye pigments, phthalocyanine pigments, such as copper phthalocyanine and its derivatives, and quinacridone pigments.

Examples of organic dyes include acid dyes, direct dyes, 1-disperse dyes, and oil-soluble dyes, 1-mixture metal oil-soluble dyes, and the like.

The colorant may be used in the usual amount range (e.g., 5 to
(within a range of 35% by weight).

This heat-softening layer may further contain a fluorine-based surfactant, and by containing the fluorine-based surfactant, the blocking phenomenon of the ink layer can be prevented.

The thermosoftening layer in the thermal transfer recording medium of the present invention is formed by coating an aqueous emulsion of the thermoplastic resin, thermofusible substance, ionomer, and other components constituting this layer.

Aqueous emulsions of thermoplastic resins and thermofusible substances are produced by emulsifying thermoplastic resins and thermofusible substances in water using existing methods such as phase inversion, high-pressure emulsification, and ultrasonic dispersion using a system containing an emulsifier. It can be prepared by The thermoplastic resin and the thermofusible substance may be mixed in advance and then emulsified, or they may be separately emulsified and then mixed.The emulsifier used in this case is as follows: Nonionic emulsifiers, anionic emulsifiers,
Either a cationic emulsifier or an amphoteric emulsifier may be used.

Ionomers are also dissolved in water in the usual way.

Dispersion or emulsification can be used.

In addition, in order to adjust the viscosity of the aqueous emulsion used for aqueous coating of the heat-softening layer, thickeners such as sodium polyacrylate and substances that improve surface slipperiness such as colloidal silica are added. Furthermore, in addition to the fluorine-containing surfactant, anionic, cationic, and nonionic monoampholytic surfactants may be contained in the aqueous emulsion. ,
A water-soluble polymer may be added, for example, polyvinylpyrrolidone, polyvinyl alcohol, water-soluble polyurethane, water-soluble acrylic.

Typical examples of water-soluble polymers include water-soluble polyester and water-soluble polyamide.

By applying the aqueous emulsion thus prepared to form a thermosoftening layer, the quality of printing on rough vapor is improved. This is because the heat-softening layer-forming component particles that make up the aqueous emulsion exist independently as particles even after coating (even though the shape changes to various shapes such as 1M matrix, plate, and ellipse). It is assumed that this is because of this.

The ionomer contained in this heat-softening layer is itself a resin that is strong and has good stretchability. Furthermore, by coating the heat-melting layer of the heat-sensitive transfer recording medium of the present invention, this ionomer forms particles together with the components constituting this layer. and is contained in this layer.

Therefore, microscopically, during thermal transfer, these particles independently transfer to the recording medium to be transferred. Due to its good stretchability, tailing is less likely to occur in the printed portion, making it possible to print with good quality.

The viscosity of the heat-softening layer prepared in this way is
400 to 8000 cps at 100°C is preferred.

In addition, the thickness of the thermosoftening layer is usually 0.6 to 5.0 gm.
(preferably 1.0 to 4 ILm).

-Others- The heat-sensitive transfer recording medium of the present invention thus obtained is as follows:
There are no particular limitations on its planar shape, and it is generally used in the form of a typewriter ribbon or a wide tape used in line printers. Further, for color recording, a heat-sensitive transfer recording medium may be provided in which a peeling layer or a heat-softening layer containing colorants of several different tones is coated in stripes or blocks.

This thermal transfer recording medium can be used in the same way as a normal thermal transfer recording medium.

[Effects of the Invention] The heat-sensitive transfer recording medium of the present invention contains the ionomer in the heat-sensitive heat-softening layer without forming a continuous layer with the components constituting this layer. In addition to being able to perform transfer with good quality even on low-grade transfer media, the ionomer has good stretchability in the form of particles, etc. (others such as mica-like, mica-like, Since wR is continuously expressed in each constituent unit (including forms that are not continuous layers such as plate-like shapes), tailing and stringing phenomena are less likely to occur.
Print quality improves.

Furthermore, by applying the heat-softening layer containing the ionomer in an aqueous system, it has excellent processability in terms of manufacturing equipment cost, working environment, safety, and production cost.

[Example] Hereinafter, an example of the present invention will be described, and the present invention is not limited thereby. In addition, "parts" used below indicates "iI! parts by amount".

(Example 1): The following coating composition was hot-melt coated onto a 1.54 m polyethylene terephthalate film to a film thickness of 1.8 m to form a release layer of the present invention.

Paraffin wax (melting point 70°C)...80 parts Ethylene-vinyl acetate copolymer...10 parts Carnauba wax...10 parts Next, the coating composition shown below was applied to a wire. A heat-softening layer of the present invention was formed by applying aqueous coating onto the release layer using a bar to a thickness of 1.94 m, thereby obtaining a sample of a thermal transfer recording medium of the present invention.

Paraffin water-based emulsion (emulsion prepared by emulsifying paraffin wax with a melting point of 70°C with water) / 15-part ethylene-vinyl acetate ionomer water-based emulsion [trade name: Chemivar S-100J; Mitsui Petrochemicals (
Co., Ltd.] 20 parts Acrylic aqueous emulsion 30 parts Carbon black water drink
...25 parts rosin aqueous emulsion...
...10 parts (in the above emulsion, the expression "~ parts" below is the part by weight of the active ingredient in the emulsion. The same applies hereinafter in the present invention) The thermal transfer recording medium sample was transferred to a thermal printer (24 dot serial Recording (printing) was performed on rough vapor (Fox River Bond paper, Beck smoothness 3 seconds) at a printing speed of 30 characters per second using a platen pressure of 280 g and a Hasad applied energy of 35 @ J Hat.

When the printing quality was evaluated, clear printing was obtained without fading, bleeding, or scumming.

The results are shown in Table 1.

(Comparative Example 1) A coating composition using an ethylene-vinyl acetate copolymer instead of the ethylene-vinyl acetate ionomer aqueous emulsion of the heat-softening layer in Example 1 was applied in the same manner as in Example 1. Example 1 using a thermal transfer recording medium sample
When the print quality was evaluated in the same manner as above, there was significant fading, bleeding, and background smearing, and clear prints could not be obtained.

The results are shown in Table 1.

(Comparative Example 2) A heat-sensitive transfer recording medium sample obtained by applying a coating composition using paraffin wax instead of the ethylene-vinyl acetate ionomer water-based emulsion of the heat-softening layer in the same manner as in Example 1 was prepared. When the printing quality was evaluated in the same manner as in Example 1, there was significant fading, blurring, and scumming, and clear printing could not be obtained.

The results are shown in Table 1.

(Example 2) In place of the coating composition for the release layer in Example 1, the following coating composition was used to form the 'A release layer of the present invention.

Paraffin wax (melting point 70°C)...82 parts Ethylene-vinyl acetate copolymer...8 parts Carbon black...101 Next, apply the following coating set 1&
The product was heated and dispersed in 300 parts of toluene, and after being heated, water-based coating was applied on the release layer in the same manner as in Example 1 to form a first heat-softening layer.

Paraffin wax (melting point 70°C)...50 F$ Ethylene-vinyl acetate copolymer...40 parts Carbon black...10 parts Furthermore, the following coating composition was coated with a wire bar. A second heat-softening layer was formed on the 18th softening layer to a thickness of 1.8 gm using water-based 1'IrJL to obtain a thermal transfer recording medium sample of the present invention.

Paraffin aqueous emulsion (emulsion made by emulsifying paraffin wax with a melting point of 70°C in water) 20i Acrylic aqueous emulsion 60 parts Ethylene-vinyl acetate ionomer aqueous emulsion [Product name: Chemivar S-100J ; Manufactured by Mitsui Seki Yukachu Co., Ltd.] 20 parts Fluorosurfactant [Product name: Megafac F-120] 00.5
When the printing quality was evaluated in the same manner as in Example 1 using the sample of the thermal transfer recording medium, clear printing was obtained without fading, blurring, or scumming.

The results are shown in Table 1.

(Comparative Example 3) Heat-sensitive transfer record obtained by applying a coating composition in the same manner as in Example 2, using an acrylic water-based emulsion instead of the ethylene-vinyl acetate ionomer water-based emulsion of the second heat-softening layer in Example 2. Example 2 using a media sample
When the print quality was evaluated in the same manner as above, scratches, smearing, and scumming occurred, and the print was somewhat unclear.

The results are shown in Table 1.

(Comparative Example 4) A thermal transfer record obtained by applying a coating composition in the same manner as in Example 2 using a paraffin water-based emulsion instead of the ethylene-vinyl acetate ionomer water-based emulsion in the second heat-softening layer in Example 2. When the print quality was evaluated in the same manner as in Example 2 using the medium sample, there were scratches, blurring, and scumming, and the print was slightly unclear.

The results are shown in Table 1.

The print quality was visually evaluated in the following three grades.

0... Clear alphabet reproduction.

Δ... Reproduction of the alphabet or slightly unclear.

×...The alphabet is reproduced or unclear.

(Margin below)

Claims (2)

[Claims] (1) At least one release layer and at least one heat-softening layer are laminated on the support, and at least one of the release layer and the heat-softening layer contains a colorant. 1. A heat-sensitive transfer recording medium, wherein at least one heat-softening layer contains an ionomer. (2) The thermal transfer recording medium according to claim 1, wherein the release layer adjacent to the support is coated by a hot melt coating method.