JPS63126791A - Thermal transfer recording medium - Google Patents

Abstract

PURPOSE:To obtain a thermal transfer recording medium having no support film for the purpose of reducing quality consumption, by containing ink based on a heat-meltable substance solid at ambient temp. and a colorant in a base material having a heat resistant microporous resin structure. CONSTITUTION:This thermal transfer recording medium is constituted by filling the pores of a heat resistant microporous resin structure 1 with ink based on a colorant 2 and a heat-meltable substance 3. This thermal transfer recording medium 1 is contacted with recording paper 6 and a thermal head 5 is contacted with said recording medium from tie opposite side or laser beam is projected to heat the recording medium 1. Hereupon, the ink component of the heated part is melted and thermally expanded and exudes from the pores or passes through said pores by a capillary phenomenon or the pressing force due to the thermal head to be transferred to the recording paper. When high energy recording is intended to perform in order to develop the gradation of an image, a heat resistant layer 7 is provided to the surface contacted with the thermal head 5 of the thermal transfer recording medium 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a recording medium used to transfer a recorded image by heating.

[Prior art] In recent years, non-impact printing technology has been researched as terminal equipment for OA and HA, which is rapidly becoming popular.Among these, non-impact printing technology is being studied because it is easy to maintain and operate the equipment, and can be made cheaper and smaller. Thermal transfer recording methods are considered to be promising.

However, the current thermal transfer recording method uses a thermal transfer sheet, and once this sheet is used, it must be discarded even if there are parts that do not print, so the high cost of consumables has always been a problem. .

Therefore, as a method that does not use the thermal transfer sheet, thermal rheography is a method in which semi-solid ink is heated and melted with a porous thermal head, and the ink is transferred to recording paper through ink passage holes in a heating element to form an image. Although it has been proposed, it is currently not put into practical use due to problems with image quality and recording speed.

By the way, in conventional thermal transfer sheets, the cost of the support film was higher than that of the ink layer, accounting for half of the cost of the sheet. Therefore, attempts were made to create a thermal transfer sheet that does not have this support, but this sheet has low mechanical strength because the main component is wax and the resin component is low, and after thermal transfer, holes form where the ink has transferred, so it is even worse. This caused problems such as sheet tearing and head sticking.

In order to solve the above problem, a sheet with increased resin content was proposed, but although the mechanical strength was improved, the thermal transfer recording sensitivity decreased, and the thermally transferred areas still had holes and stuck to the head. The problem that occurred could not be resolved.

[Objective] The present invention aims to solve the above-mentioned problems of the prior art and provide a thermal transfer recording medium without a support film for the purpose of reducing the cost of consumables in a thermal transfer recording method.

[Structure] The structure of the present invention for achieving the above object is that an ink whose main components are a heat-fusible substance that is solid at room temperature and a colorant is contained in a base that is a heat-resistant microporous resin structure. This is a thermal transfer recording medium.

To produce the heat-sensitive transfer recording medium of the present invention, a mixture whose main components are a heat-melting substance, a colorant, and a high-melting-point microporous structure-forming resin is formed into a film.

As shown in FIG. 1, the thus manufactured thermal transfer recording medium has ink containing a colorant 2 and a heat-fusible substance 3 as main components filled into the micropores of a heat-resistant microporous resin structure 1. It is of the state.

When this thermal transfer recording medium 1 is brought into contact with the recording paper 6 and heated by contacting the thermal head 5 from the opposite side or by irradiating with laser light, the ink components in the heated portion melt, causing thermal expansion, capillary action, etc. It oozes out from the micropores or passes through the holes and is transferred to the recording paper due to the pressing force of the thermal head or the like.

By the way, when high-energy recording is attempted to produce image gradations, the heat-resistant microporous resin structure cannot withstand the input heat, so as shown in FIG. A heat-resistant protective layer 7 may be provided on the surface in contact with the thermal head 5.

The manufacturing method and materials for the thermal transfer recording medium of the present invention, that is, the thermal transfer sheet, will be described in detail below.

That is, the ink is dispersed by mixing and dispersing a heat-fusible substance, a coloring agent, and an oil that serves to form the porosity of the resin together with an appropriate organic solvent using a dispersion device such as an attritor or a ball mill. Obtain a liquid (or a solution). Separately, a solution of a thermoplastic resin dissolved in an organic solvent is obtained, mixed with the ink dispersion, and uniformly dispersed using a mixer such as a ball mill. Next, the obtained dispersion is applied onto a support with a smooth surface (for example, a glass plate) and dried to obtain a hot-melt ink layer with the above-mentioned fine structure, which is peeled off to form a film. is obtained, which becomes the thermal transfer recording medium of the present invention. At this time,
The support side with a smooth surface is the part facing the head, and if necessary, for example, if there is hot melt substance or oil attached to that surface, it can be removed by cleaning with alcohol, hexane, etc. desirable.

The thickness of the film of the above-mentioned thermal transfer recording medium is preferably 3 μm or more from the viewpoint of stability of film strength, and desirably 5 to 25 μm.

A thickness of 10 μm or more is desired to enable multiple recordings in one change.

A wetting agent, a dispersing agent, etc. may be added to the dispersion liquid in order to improve the dispersion of the heat-fusible substance, colorant, and oil.

Also, if necessary, fillers commonly used in resin coatings of this type can be added.

The resins constituting the microporous resin structure include vinyl chloride, vinyl acetate, vinylidene chloride, nitrocellulose, cellulose butyrate, cellulose acetate, acrylic acid, methacrylic acid, acrylic ester and It is preferable to use thermoplastic resins such as monomers or copolymers of monomers selected from methacrylic acid esters, and thermosetting resins such as phenol, furan, formaldehyde, urea, melamine, alkyds, unsaturated polyesters, and epoxy. In particular, it is necessary to select a material with a high melting point (mp, 150'C or higher) from the viewpoint of heat resistance as a skeleton. If the temperature is below 150°C, it will melt under the normal heating conditions of the thermal head and cause sticking.

Particularly preferred materials include cellulose acetate butyrate, cellulose acetate propionate, and cellulose acetate. Examples of commercially available materials are shown in Table 1 below. However, the manufacturer is Eastman Chemical C.
o.

Table 1 also shows that the amount of the heat-resistant microporous resin is preferably 50% by weight or more based on the entire heat-sensitive transfer sheet in terms of the durability of the skeleton and film-forming properties.

In addition, after manufacturing the thermal transfer sheet, to prevent background stains,
It is also possible to remove oil and coloring agent adhering to the surface of the sheet by washing with a solvent or the like.

As the heat-melting substance that is solid at room temperature and used as an ink component in the present invention, heat-melting binders that constitute heat-melting inks in ordinary heat-sensitive transfer recording media can be used, such as carnauba wax and paraffin wax. , Sasol wax, microcrystalline wax, castor wax, and other waxes; stearic acid, palmitic acid, lauric acid, aluminum stearate, lead stearate, barium stearate, zinc stearate, zinc palmitate, methyl hydroxystearate, Derivatives such as higher fatty acids such as glycerol monohydroxystearate or their metal salts and esters; polyethylene, polypropylene, polyisobutylene, polyethylene wax, polyethylene oxide, polytetrafluoroethylene, ethylene-acrylic acid copolymer, ethylene-acrylic acid Thermoplastic resins made of olefins alone or copolymers, such as ethyl copolymers, ethylene-vinyl acetate copolymers, or derivatives thereof, are used. These holding materials may be used alone or in combination of two or more in an amount of 5 parts per 100 parts of the thermoplastic resin constituting the thermal transfer layer.
It is used in a proportion of 0 to 200 parts.

As the pore-forming auxiliary oil, any liquid, semi-solid, or heat-melting solid may be used as long as it is incompatible with the above-mentioned thermoplastic resin and is non-volatile. As liquid retaining materials, for example, animal and vegetable oils such as cottonseed oil, rapeseed oil, and whale oil; or mineral oils such as motor oil, spindle oil, and dynamo oil are used; as semisolid carriers, for example, lanolin, lanolin derivatives, petrolatum, lard, etc. are used. .

This oil is preferably the above-mentioned lanolin derivative oil, more preferably lanolin fatty acid or lanolin fatty acid ester oil, specific examples of which include Neocoat 0ES-181, 0ES-183, L
FC-50M, 1313-3l02 (all manufactured by Yoshikawa Oil)
Examples include.

Although these may be contained in an amount of 20% by weight or more, it is also possible to add a low-viscosity oil having a viscosity of 300 CpS or less in consideration of lowering the viscosity.

Specific examples of the coloring agent include the following.

Coloring dyes and color pigments may be used, but dyes can provide images with more preferable gradation.

Specifically, the colored dyes used in this invention include the following direct dyes, acid dyes, basic dyes, mordant dyes, sulfur dyes,
There are vat dyes, azoic dyes, oil dyes, heat sublimable disperse dyes, etc.

1) Direct dyes: Direct Sky Blue, Direct Black W, etc.

2) Acid dye: Tartrazine, Acid Violet 6
B, Acid Fast Red 3G, etc.

3) Basic dyes: safranin, auramine, crystal violet, methylene blue, rhodamine B, Victoria blue B, etc.

4) Mordant dyes: Sunchromine Fast Blue-MB, Elio from Azurol B1 Alizarin Yellow B, etc.

5) Sulfur dye: Sulfur Brilliant Green 4G, etc.

6) Vat dyes: indanthremble, etc.

7) Azoic dyes: naphthol AS, etc.

8) Oil dye Nigrosin, Spirit Black EB1
Varifast Orange 3206, Oil Black 215
, Butter Yellow, Sudan Blue ■, Oil Red B
10-Damin B et al.

9) Heat-sublimable disperse dye (9-1) Monoazo disperse dye: Disbird's First Yellow G1 Disbird's First Yellow 5G,
Divers First Yellow 5R, Divers Red R, etc.

(9-2) Anthraquinone disperse dye: Disbird's First Violet OR, Disbird's First Violet 81' Disperse Blue Extra, Disbird's First Brilliant Blue B, etc.

(9-3) Nitrodiphenylamine-based disperse dyes: Disperse F7-St Yellow RR, Disperse Fast Yellow GL, etc.

These dyes are preferably in a dissolved state.

Examples of colored pigments include colored fine particle pigments and monoazo pigments.

Specific colored fine particle pigments are shown below. All are made by Hoechst, and the color index numbers are shown in parentheses.

Permanent Yellow GG, 2 (Pigment Yellow 17), Permanent Yellow DHG Transformer 02
(Pigment Yellow 12), Novopalm Yellow HRO3 (Pigment Yellow 83), Hansa Brilliant Yellow 5GXO2 (Pigment Yellow 74), Permanent Orange RLOI (Pigment Orange 34), Novopalm Red HFG (Pigment Orange 38), Novopalm Red HFT (Pigment Red) 175), Permanent Lake Red LCLLO2 (Pigment Red 53:1), Novo Palm Red HF4B (Pigment Red 187),
Permanent Carmine FBBO2 (Pigment Red 146), Permanent Lupine L6B (Pigment Red 57:1), Hostapalm Pink Hytrans (Pigment Red 122), Reflex
Blue R50 (Pigment Blue 61) Examples of monoazo pigments include compounds represented by the following structural formula.

X-N=N-Y however, X didiazonium salt residue Y2 coupler left on base Particularly specific examples of product names include the following.

(1) 5ico Fast Yellow D 13
55 (made by BASF) (2) 5ico Fast
Yellow mouth 1250 (BASFv!A>(3
) Lake Red LC (manufactured by Hoechst) The structural formula is (4) Lake Red C405 (manufactured by Dainichiseika) (
5) FaSt Red 1547 (manufactured by Dainichiseika)
The structural formula is: In order to further improve the gradation obtained by the present invention, it is also possible to add a gradation control agent to be described later.

In other words, the gradation control agent has better wettability and compatibility with the resin than low-melting substances such as oil and wax, which are the main components of hot-melt ink, and is firmly held in the sponge resin structure. It appears to be possible to delicately control the pore size of the tissue to make it smaller. Therefore, even when thermal energy is applied, it is not transferred out, but is retained in the porous structure, and acts as a good gradation control agent by controlling the transfer of colorants and ink existing around it. it is conceivable that. In addition, by adding a gradation control agent, the unevenness of the surface increases, the contact point with the receptor becomes smaller, and the effect of preventing background smearing can be cited.

As the gradation control agent, the following are shown as specific examples.

1) Acicular crystal pigment (Japanese Patent Application No. 60-38868) 2) Azo pigment (Japanese Patent Application No. 60-192098) 3) Phthalocyanine pigment (Japanese Patent Application No. 60-168562@) Addition of the above gradation control agent The amount is 0.5 per part by weight of dye.
~10 parts by weight, preferably 1 to 5 parts by weight.

Hereinafter, the present invention will be specifically explained with reference to Examples. Note that the amounts (parts) of each component described in the Examples are parts by weight.

Example 1 Colorant: Ne0ZapOn Blue 807 (BA
SF) 10 parts Carnauba wax N011 (Noda Wax) 15 parts Lanolin fatty acid oil (OES-183, Furukawa Oil)
10 parts dispersant 0.5 parts liquid paraffin 3 parts Above hot melt ink valve 90
Quantum dispersion was carried out for about 48 hours in a ball mill with a mixed solution of 100 parts of methyl ethyl ketone and 130 parts of toluene at .degree.

Then 20% by weight of cellulose acetate butyrate C
AB 381-0.5 (Eastman Chemical
al m, p, 155-165 °C) solution (resin 1
0 parts, toluene 20 parts, methyl ethyl ketone 20 parts)
300 parts of the ink dispersion was added to the above ink dispersion and dispersed in a ball mill for about 1 hour to prepare a coating of a heat-sensitive transfer composition.

This coating material was coated on a smooth glass plate using a wire bar, dried for 1 minute at a drying temperature of io O'C, and peeled off to produce a hot melt ink film with a thickness of about 8 μm.

The transfer medium thus obtained is stacked so that the surface opposite to the top surface of the glass plate faces the plain paper that serves as the receiver, and the surface of the transfer medium is heated using a printer with a commercially available serial thermal head to produce an image by varying the heating energy. When recording was carried out, it was possible to obtain a clear cyan-colored printed image without causing any tearing of the ink sheet during supply or winding up, or any sticking phenomenon after recording.

Example 2 Coloring agent: Kayaset Black G (manufactured by Nippon Kayaku) 10 parts Carnauba wax N0.1 (manufactured by Noda Wax) 10 parts Lanolin fatty acid oil (OES-183) 20 parts Powder 0.5 parts Liquid paraffin 3 parts Top When an ink film was prepared using the above heat-melting ink valve in the same manner as in Example 1 and an image was recorded, the ink sheet did not tear during feeding or winding up, and the sticking phenomenon after recording did not occur. It was possible to obtain a clear black printed image without any problems.

Example 3 Colorant: Neozapon Red 365 (BA
SF) 10 parts Carnauba wax N011 (Noda Wax) 15 parts Lanolin fatty acid oil (OES-183, Yoshikawa Oil) 10 parts Powder
0.5 part liquid paraffin
3 parts of the above hot-melt ink components are quantum dispersed in a ball mill at 90'C with a mixed solution of 100 parts of methyl ethyl ketone and 130 parts of toluene for about 48 hours.

Then 10% by weight of cellulose acetate butyrate c
AB-171-153 (Eastman Chemical
Al) solution (10 parts of resin, 30 parts of toluene, 60 parts of methyl ethyl ketone) was added to the above ink dispersion and dispersed in a ball mill for about 1 hour to prepare a coating of a thermal transfer composition.

This paint was coated on a smooth glass plate using a wire bar, dried for 1 minute at a drying temperature of IOO'C,
This was peeled off to produce a heat-melting ink film with a thickness of approximately 12 μm.

The upper surface of the glass plate was roughly cleaned with hexane to remove adhered substances.

The transfer medium thus obtained is stacked so that the surface opposite to the cleaned surface faces the plain paper serving as the receiver, and heating energy is applied to the back side of the transfer medium using a printer with a commercially available serial thermal head. When the image was recorded, a clear red printed image could be obtained.

In the case of thermal transfer media with a heat-resistant protective layer on the back side,
Next, a heat-resistant protective layer made of silicone resin, fluororesin, polyimide resin, epoxy resin, phenol resin, melamine resin, thermosetting acrylic resin, nitrocellulose, etc. is provided on one side of the hot-melt ink film by a solution coating method or the like. By providing this, it is possible to improve the heat resistance of the heat-melting ink film and prevent sticking etc. during heating of the thermal head. The heat-resistant protective layer may contain fillers such as calcium carbonate, silica, titanium dioxide, zinc oxide, etc. as appropriate.

It is also possible to use conductive pigments such as carbon in the protective layer to make the protective layer conductive or low-resistance, and apply electric current to generate Joule heat to melt and transfer the ink components. can.

The thickness of the heat-resistant protective layer is 0.1 to 5μ,
Preferably it is 0.3 to 3μ.

Examples of heat-sensitive transfer media provided with a heat-resistant protective layer will be shown below.

Example 4 Colorant: Neozapon Blue 807 (BA
SF) 10 parts Carnauba wax N0.1 (Noda Wax) 15 parts Lanolin fatty acid wax (OES-183, Furukawa Oil) 10 parts Powder
0.5 part liquid paraffin
3 parts of the above hot-melt ink components are quantum dispersed in a ball mill at 90'C with a mixed solution of 100 parts of methyl ethyl ketone and 130 parts of toluene for about 48 hours.

Then 20% by weight of vinyl chloride vinyl acetate copolymer resin VYHHU
300 parts of a solution (manufactured by Nion Carbide) (10 parts of resin, 20 parts of toluene, 20 parts of methyl ethyl ketone) was added to the above ink dispersion and dispersed in a ball mill for about 1 hour to prepare a coating of a thermal transfer composition.

This paint was coated on a smooth glass plate using a wire bar, and after drying for 1 minute at a drying temperature of 100'C,
This was peeled off to produce a heat-melting ink film with a thickness of approximately 8 μm.

Next, the following coating solution for forming a heat-resistant protective layer was prepared by sufficiently mixing and dispersing materials having the following composition.

Acrylic acrylate 10 parts 2-ethoxyethyl acrylate 3 parts Benzoyl ether 1 part Silica 2.5 parts Toluene
35 parts methyl ethyl ketone (ME
K) 15 parts This coating solution is diluted by appropriately adding a mixture of toluene and MEK, coated on the above heat-melting ink film with a wire bar, and cured by irradiating it with a 1kW high-pressure mercury lamp for 5 minutes to form a thick film. A slippery heat-resistant protective layer having a thickness of approximately 1.5 μm was formed.

The thus obtained transfer medium was stacked so that the ink side faced the plain paper on the receiver, and an image was recorded from the back side of the transfer medium using a commercially available printer with a serial thermal head by varying the heating energy. , a clear cyan-colored printed image could be obtained.

Example 5 Colorant: Kayaset Black G (manufactured by Nippon Kayaku) 10 parts Carnauba wax N011 (manufactured by Noda Wax) 10 parts Lanolin fatty acid oil (OES-183) 20 parts Powder 0.5 parts Liquid paraffin 3 parts Example 4 When the image was recorded in exactly the same manner as above, a clear black printed image could be obtained.

Example 6 Colorant: Neozapon Red 365 (BA
Made by SF〉10 parts Carnauba wax No. 1 (made by Noda Wax) 15 parts Lanolin fatty acid wax (OES-183, made by Furukawa Oil Co., Ltd.) 10 parts Powder
0.5 part liquid paraffin
3 parts of the above hot melt ink components are thoroughly dispersed at 90°C with a mixed solution of 100 parts of methyl ethyl ketone and 130 parts of toluene in a ball mill for about 48 hours.
Then 10% by weight of cellulose acetate butyrate C
AB-381-0,5 (Eastman Chemical
500 parts of a solution (10 parts of resin, 30 parts of toluene, 60 parts of methyl ethyl ketone) was added to the above ink dispersion and dispersed in a ball mill for about 1 hour to prepare a coating of a heat-sensitive transfer composition.

This paint was coated on a smooth glass plate using a wire bar, and after drying for 1 minute at a drying temperature of ioo'c,
This was peeled off to produce a heat-melting ink film with a thickness of approximately 12 μm.

Next, materials having the following composition were sufficiently mixed and dispersed to prepare a coating liquid for a slippery heat-resistant protective layer.

Methyl methacrylate 10 parts n-butyl acrylate 2 parts Benzoyl peroxide 0.1 part Silica
2.5 parts toluene
35 parts isopropyl alcohol (IPA) 15
Add a mixture of toluene and IPA appropriately to this coating solution, dilute it, apply it to the above heat-melting ink film with a wire bar, and dry at 100°C for 1 minute to form a slippery heat-resistant film with a thickness of about 1.5μ. A protective layer was formed.

The transfer medium obtained in this way was overlapped so as to face the plain paper that was the receptor, and an image was recorded from the back side of the transfer medium using a printer with a commercially available serial thermal head by changing the heating energy. A red printed image could be obtained.

Furthermore, when the same area was repeatedly printed and recorded on roughly the same sheet, the result was that the image density hardly changed up to 3 times, indicating that it was possible to perform multiple recordings.

[Effects] As is clear from the above explanation, the heat-sensitive recording medium of the present invention achieves low cost (about 172 yen of the conventional cost), and does not use a support film, which was a factor of high cost in the past, and requires high-energy manual labor. It was possible to form a film with only a heat-melting ink layer without forming holes even if the film was heated, and by using this film, it was possible to obtain a printed image almost the same as that of a conventional thermal transfer sheet.

It is also possible to perform recording many times, making it possible to further reduce costs.

Also, multicolor images can be obtained by selecting various colorants.

[Brief explanation of the drawing]

FIGS. 1 and 2 are explanatory diagrams of a state in which transfer is performed using a thermal transfer recording medium that is a specific example of the present invention. DESCRIPTION OF SYMBOLS 1... Thermal transfer recording medium, 2... Colorant, 3... Heat-melting substance, 4... Heat-resistant microporous resin structure, 5... Thermal head, 6... Recording paper, 7...Heat-resistant protective layer.

Claims (2)

[Claims] (1) A heat-sensitive transfer recording medium characterized in that an ink whose main components are a heat-fusible substance that is solid at room temperature and a colorant is contained in a base that is a heat-resistant microporous resin structure. (2) The heat-sensitive transfer recording medium according to claim 1, which has a heat-resistant protective layer on one side.