JPH02153792A - Thermal transfer recording medium - Google Patents

Abstract

PURPOSE:To improve a dot reproducibility and to form a high-quality printing image superior in fixing properties by a method wherein a contact surface of a hot melt layer and a thermal softening layer has irregularities, and a colorant is incorporated in either the hot melt layer or the thermal softening layer. CONSTITUTION:For example, on a polyethylene terephthalate film, a composition for a hot melt layer made of a paraffin wax, an ethylene-vinyl acetate copolymer, and a carbon black is applied to form the hot melt layer. In this case, the coating is conducted by a hot melt method using an oblique line gravure pattern, and the surface of the hot melt layer has Ra (frequency of irregularities) of 0.3-1.5. Thereafter, a composition for a thermal softening layer of 100wt.% ethylene-vinyl acetate copolymer is applied on the hot melt layer to form the thermal softening layer. In this manner, a thermal transfer recording medium is obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a thermal transfer recording medium, and more specifically, it has excellent dot reproducibility and is sufficient even for transfer media with low surface smoothness. The present invention relates to a thermal transfer recording medium on which a printed image having excellent fixing properties can be formed.

[The problem to be solved by the prior art and the invention] In recent years, with the spread of thermal transfer devices such as word processors,
2. Description of the Related Art Heat-sensitive transfer recording media having a heat-melting ink layer provided on a support have come to be widely used.

By the way, in conventional thermal transfer recording media, when thermal transfer is performed, the non-heated portions of the ink layer do not peel off in a planar manner, and only the heated portions of the ink layer by the thermal head are heated.
Accurately transferred to the transfer medium. Various studies have been made to improve the dot reproducibility of so-called thermal transfer recording media. Attempts are being made to reduce the cohesive force of

However, in any case, such thermal transfer recording media attempt to improve the dot reproducibility by reducing the cohesive force of the ink layer. It was easy to cause stains, and it was difficult to say that the dot reproducibility had been sufficiently improved.

Furthermore, when printing on these thermal transfer recording media, they are easily affected by the surface smoothness of the transfer medium. For example, when printing on rough paper with a low surface smoothness, the printed image may be affected by the surface smoothness of the rough paper. A good bridge causes deterioration in printing quality such as voids, which is thought to be due to the inability to form a structure, due to the fine irregularities of the paper. On the other hand, this method has the disadvantage of inevitably deteriorating the reproducibility of one dot.

This invention has been made based on the above circumstances.

That is, an object of the present invention is to perform thermal transfer by:
A thermal transfer recording medium that can improve dot reproducibility without causing background smudges, and can form high-quality printed images with excellent fixation even on transfer media with low surface smoothness. Our goal is to provide the following.

[Means for Solving the Problem] The invention according to claim 1 for solving the problem comprises providing a heat-softening layer on a support with a heat-melting layer interposed therebetween; The contact surface between the thermofusible layer and the thermosoftening layer is an uneven surface, and at least one of the thermofusible layer and the thermosoftenable layer contains a coloring material. It is a recording medium.

The invention according to claim 2 is the thermal transfer recording medium according to claim 1, wherein the contact surface has an average surface roughness of 0.3 to 1.5.

This invention will be explained in detail below.

In the heat-sensitive transfer recording medium of the present invention, the heat-fusible layer and the heat-softening layer are in contact with each other while forming a laminate surface.

For example, as shown in FIG. 1, the heat-sensitive transfer recording medium of the present invention is formed by a heat-fusible layer 2 and a heat-softening layer 3 provided on a support 1, which are in contact with each other on a finely uneven surface.

In the uneven surface, it is preferable that the distance between adjacent protrusions 4 is smaller than the diameter of each dot of a thermal head used for thermal transfer.

Furthermore, considering the generally used thermal head, the uneven surface of the heat-fusible layer has an unevenness frequency (hereinafter sometimes simply referred to as Ra) of 0.3 to 1.5. preferable.

In addition, the said Ra was calculated|required by measuring 2.5 mm of the said heat-fusible layer surface with a cut-off of 0.25, and a stylus force of 30 mg with three-dimensional roughness measuring instrument 5E-3FK (manufactured by Koita Institute).

The unevenness realizes good dot reproducibility when thermal transfer is performed using this thermal transfer recording medium.

That is, as shown in FIG. 1, the heat-sensitive transfer recording medium of the present invention has a heat-fusible layer 2 containing a heat-fusible material, which will be described later, on a support 1. I
A heat-softening layer 3 made of a composition with high J concentration is provided, and on the other hand, the convex portions 4 on the surface of the heat-fusible layer 2 have a thickness that is smaller than the concave portions 5. For example, when the heat-sensitive transfer recording medium is heated and transferred from the support l side with the dots 6, the position of the convex portion 4 containing a large amount of the heat-fusible substance, that is, the heat-fusible layer A1-B, , A2-B2 corresponding to the heating of the dot 6 of 2
Achieve good rupture at certain positions.

The uneven surface increases the contact area between the heat-fusible layer and the heat-softening layer, and improves the adhesion between the heat-fusible layer and the heat-softening layer.

When thermal transfer is performed, planar peeling of the heat-softening layer from the heat-fusible layer is also prevented.

Next, the structure of the heat-sensitive transfer recording medium of the present invention will be explained in the order of the support, the heat-melting layer, and the heat-softening layer.

1.Support 1. The support in the thermal transfer recording medium of the present invention preferably has good heat resistance strength and high dimensional stability.

The materials include, for example, papers such as plain paper, capacitor 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. Any metal sheet such as foil is preferably used.

The thickness of the support is usually 3 Gpm or less, preferably 2 to 3 Gpm.
It is within the range of 30 μm. If the thickness of the support exceeds 30 pm, thermal conductivity may deteriorate, leading to deterioration in print quality.

In addition, in the thermal transfer recording medium of this invention.

The structure on the back side of the support is arbitrary, and for example, a backing layer such as an anti-sticking layer may be provided.

Adjacent to the support or via, for example, conventionally known release layers or anchor layers.

Next, a heat-fusible layer, which will be described in detail, is laminated.

- Heat-melting substance The heat-melting layer in the present invention mainly contains a heat-melting substance and, if necessary, a coloring material.

Note that the coloring material in this invention may be contained in at least one of the heat-fusible layer and the heat-softening layer described below.

Specific examples of the heat-melting substances include vegetable waxes such as carnauba wax, wood wax, auriculie wax, and Nispar wax; animal waxes such as beeswax, insect wax, shellac wax, and spermaceti wax; paraffin wax, microcrystalline wax, Petroleum waxes such as polyethylene waxes, ester waxes, and acid waxes; and waxes such as mineral waxes such as montan wax, osichelite, and ceresin; and in addition to these waxes, palmitic acid, stearic acid, Higher fatty acids such as margaric acid and behenic acid; higher alcohols such as palmityl alcohol, stearyl alcohol, behenyl alcohol, marganyl alcohol, myricyl alcohol and eicosanol; cetyl palmitate, myricyl palmitate, cetyl stearate and myricyl stearate, etc. Higher fatty acid ester; acetamide,
Amides such as propionic acid amide, palmitic acid amide, stearic acid amide and amide wax; and higher amines such as stearylamine, behenylamine and palmitylamine.

These may be used alone or in combination of two or more.

Among these, preferred is a wax whose melting point is within the range of 50 to 100°C as measured using Yanagiki MJP-2 type.

The content of the heat-fusible substance in the heat-fusible layer is normally based on the total amount of the hot-fusible magnetic layer composition.

It is within the range of 20 to 100 ffi amount%, preferably.

It is within the range of 50 to 90% by weight.

Examples of the coloring material include pigments such as inorganic pigments and organic pigments, and dyes.

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

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

Examples of heavy industry dyes include acid dyes, direct dyes, disperse dyes, oil-soluble dyes, and metal-containing oil-soluble dyes.

The content of the coloring material in the heat-fusible layer is usually 1 to 5 to 3.
Within the range of 5% by weight, preferably.

It is within the range of 10 to 30% by weight.

The heat-fusible layer of the present invention may contain a thermoplastic resin in addition to the heat-fusible substance and the coloring material.

The thermoplastic resins include ethylene copolymers, polyamide resins, polyester resins, polyurethane resins, polyolefin resins, acrylic resins, vinyl chloride resins, cellulose resins, rosin resins, ionomer resins, and Resins such as petroleum resins; Elastomers such as natural rubber, styrene-butadiene rubber, isoprene rubber, chloroprene rubber, and diene copolymers; Rosin derivatives such as ester gum, rosin maleic resin, rosin phenolic resin, and hydrogenated rosin: and a softening point of 50 to 15 for phenolic resins, terpene resins, cyclopentadiene resins, aromatic hydrocarbon resins, etc.
Examples include polymeric compounds at 0°C.

Among the various thermoplastic resins, ethylene copolymers are preferred.

Examples of the ethylene copolymer include ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene-isobutyl acrylate copolymer, and ethylene-acrylic acid. Examples include copolymers, ethylene-vinyl alcohol copolymers, ethylene-vinyl chloride copolymers, and ethylene-acrylic acid metal salt copolymers.

These thermoplastic resins may be used alone or
You may use two or more types in combination.

In this invention, the melt index (MI value) of the thermoplastic resin component that can be suitably used is usually in the range of 2 to 1500, preferably 20 to 5.
It is within the range of 00.

The content of the thermoplastic resin component in the heat-fusible layer is 1
Usually within the range of 0 to 40% by weight, preferably 3 to 40% by weight.
It is within the range of 20% by weight.

The average layer thickness of the heat-fusible layer is usually 0.3 to 5. OIL
m, preferably 0.5 to 4.0 gm.

-Thermo-softening layer The heat-softening layer of the heat-sensitive transfer recording medium of this invention is:

It is made of a composition having a lower cohesive force than the heat-fusible substance, and contains a coloring material if necessary.

The coloring material may be contained in at least one of the heat-melting layer and the heat-softening layer.

The heat-softening layer exhibits good fixing properties even to, for example, rough paper with low surface smoothness.

The composition of the thermosoftening layer is mainly composed of a thermoplastic resin.

As the thermoplastic resin, various thermoplastic resins that can be used for the thermofusible layer can be suitably employed.

Among these, preferred are ethylene-vinyl acetate copolymers (EVA) obtained by polymerization reaction of ethylene and vinyl acetate, derivatives thereof, acrylic resins, and polyester resins.

Examples of the acrylic resin include acrylic resins obtained by polymerizing monobasic carboxylic acids such as (meth)acrylic acid or esters thereof, and at least one type of compound that can be copolymerized with these. Can be done.

Examples of the carboxylic acid or its ester include (
(meth)acrylic acid, (meth)acrylic acid methyl ester, (meth)acrylic acid ethyl ester, (meth)acrylic acid impropyl ester, (meth)acrylic acid butyl ester, (meth)acrylic acid isobutyl ester, (
meth)acrylic acid amyl ester, (meth)acrylic acid hexyl ester, (meth)acrylic acid octyl ester, (meth)acrylic acid-2-ethylhexyl ester, (meth)acrylic acid decyl ester, (meth)acrylic acid dodecyl ester, Examples include (meth)acrylic acid hydroxyethyl ester and (meth)acrylic acid hydroxyethyl ester.

Further, examples of the above copolymerizable compounds include vinyl acetate, vinyl chloride, vinylidene chloride, maleic anhydride,
Examples include S-water fumaric acid, styrene, 2-methylstyrene, chlorostyrene, acrylonitrile, vinyltoluene, N-methylol(meth)acrylamide, N-butoxymethyl(meth)acrylamide, vinylpyridine, and N-vinylpyrrolidone. .

The polyester resin is not particularly limited as long as it does not impede the object of the present invention, but is preferably a saturated linear polyester having a softening point of 50 to 100°C.

Examples of the saturated linear polyester having a softening point of 50 to 100°C include polyester compounds such as glyptal resin, glyptal resin, isophthalic acid resin, terephthalic acid resin, polyarylate, and aliphatic polyester. .

Among these, it is preferable to have an ester bond (-
Co-0-), which are solid at room temperature, are linear polyesters and derivatives thereof, and polyester waxes are particularly preferred.

In this invention, polyester wax is one that contains three or more ester bonds (-Co-0-) in one molecule and has a weight average molecular weight (My) of 1500 to 12
Refers to compounds within the range of 000.

Such a compound can be obtained, for example, as a polycondensate of a polyhydric alcohol and a polybasic acid or a ring-opened polymer of a lactone compound.

Preferred specific examples of the polyester wax are shown below.

(1) Polycondensate of adipic acid and 1,4-butanediol (Mw = 2QOO, softening point 55°C).

(2) ε-caprolactone; (3) Sebacic acid-decamethylene glycol copolymer
(Mw = 3000), (4) Adipic acid-propylene glycol copolymer (Mw = 3
000), (5) ω-hydroxydecanoic acid polymer Mw = 4000).

(6) δ-valerolactone polymer (Mw = 4000).

The polyester wax that can be suitably used in the present invention may be a compound containing such polyester in the molecule in block form or graft form, and furthermore, may have an alkyl group or an amide group at the end. It may also have one or more hydroxyl groups, amino groups, carboxyl groups, or carbonyl groups, and it may also have some ether bonds, amide bonds, or urethane bonds in the main chain or side chain. It may be something.

Polyester waxes are not limited to those synthesized using dibasic acids, dihydric alcohols, polybasic acids and polyhydric alcohols shown in the above examples, but also those synthesized using other dibasic acids, dihydric alcohols, polybasic acids and polyhydric alcohols. It may also be one synthesized using a hydric alcohol.

Polyester waxes can also be obtained commercially. Specifically, the ``Plaxel'' [product name: Daicel Chemical] series, the ``Elythyl'' [product name;
Examples include the Unitika series.

In this invention, the weight average molecular weight of the polyester compound that can be suitably used is 1, usually 100
It is within the range of 0 to 70,000, preferably 2,000 to
It is within the range of 20,000.

The content of the thermoplastic resin in the heat-softening layer is:
1, usually 40 to 10 per total amount of heat-softening layer heavy oxides
It is within the range of 0 fi amount %, preferably within the range of 60 to 80 weight %.

These may be used alone or in combination with the two divine tools E.

The average layer thickness of the heavy industry thermosoftening layer is usually 0.3 to 2.5 bar m.
, preferably 0.5 to 2.0 m.

Note that the thermosoftening layer may contain a coloring material in addition to the thermoplastic resin.

As the coloring material, the same coloring material as that used for the heat-fusible layer can be used.

When the heat-softening layer contains the coloring material, the content of the coloring material in the heat-softening layer is usually within the range of 5 to 30% by weight, preferably within the range of IO to 1%. be.

The heavy-duty heat-melting layer and the heat-softening layer having these compositions are formed on the support in a manner similar to the above.

The heat-fusible layer can be formed by a folatmelt coating method, an aqueous coating method,
Directly onto the support by using a coating method using an organic solvent, etc.
Alternatively, it can be coated through an intermediate layer.

The heat-fusible layer has the unevenness on its surface.

The method for forming the unevenness is, for example, after forming the heat-fusible layer on the support by the coating method.

A method of embossing the surface, a method of forming the unevenness using a gravure pattern, a method of dissolving a hot melt magnetic layer composition in two or more types of organic solvents with different boiling points, and using the solution to form a hot melt magnetic layer composition on a support. When forming a layer, a method may be mentioned in which the unevenness is formed by using a difference in the volatility of the organic solvent.

Moreover, the unevenness can also be formed by containing a filler in the heat-fusible layer.

As the filler, organic fine particles, inorganic fine particles, etc. can be used, such as silica.

Examples include fine particles such as calcium carbonate and resin.

In any case, the method for forming the unevenness is not particularly limited as long as it is a method that can form the unevenness on the surface of the thermofusible layer and does not impede the purpose of the present invention. .

Next, the thermosoftening layer is formed directly on the thermofusible layer having the uneven surface or via an intermediate layer.

As the method for forming the heat-softening layer, a formation method similar to the method for forming the heat-fusible layer can be adopted,
Among these, preferred are aqueous coating methods, coating methods using organic solvents, and the like.

After each layer is coated in this manner, it is optionally subjected to a drying process, a surface smoothing process, etc., and then cut into a desired shape to obtain the thermal transfer recording medium of the present invention.

The heat-sensitive transfer recording medium thus obtained can be used, for example, in the form of a tape or a typewriter ribbon.

The heat-sensitive transfer method using this heat-sensitive transfer recording medium is not different from a normal heat-sensitive transfer recording method, but will be explained using an example in which the most typical thermal head is used as a heat source.

First, the heat/softening layer of the thermal transfer recording medium and the transfer medium,
For example, a heat-melting layer and a heat-softening layer are brought into close contact with a transfer paper, and if necessary, are further pressed from the back side of the transfer paper with a platen while applying heat pulses with a thermal head to form a heat-melting layer or a heat-softening layer that corresponds to a desired printing or transfer pattern. locally heated.

The temperature of the heated portions of the heat-fusible layer and the heat-softening layer increases, and the heated portions are quickly softened and transferred onto the transfer medium.

At this time, since the heat-fusible layer and the heat-softening layer are in contact with each other on the uneven surfaces, good dot reproducibility is achieved as described above, and the heat-fusible layer and the heat-softening layer are in contact with each other on the uneven surface. In addition to preventing surface peeling from the layer, since the thermosoftening layer contains the thermoplastic resin, it exhibits high adhesion even to the transfer medium with a low surface smoothness, and provides fixation after printing. A high quality printed image with good quality can be formed.

〔Example] Next, examples and comparative examples of the present invention will be shown.

This invention will be explained in more detail.

(Example 1) The following hot melt magnetic layer composition was deposited on a polyethylene terephthalate film having a thickness of 3.5 μm to a dry average film thickness of 2.5 μm. OI
A heat-fusible layer was formed by coating in an amount of Lm.

The coating was carried out using a pot-melt method using a diagonal gravure pattern.

Ra of the surface of the heat-fusible layer formed in this way is 0.
．． It was 5.

Heat-melting footwear composition Paraffin wax as...80 weight [L% Ethylene-vinyl acetate copolymer...10 weight% Carbon black...10 weight% Then, the following is described. The heat-melt-softening layer composition is coated on the heat-meltable layer to have a dry average thickness of 0.97 Lm to form a heat-meltable layer to produce the heat-sensitive transfer recording medium of the present invention. did.

The coating was carried out using a coating method using an organic solvent (MEK, 35° C.).

Ethylene-vinyl acetate copolymer, 100% by weight (vinyl acetate content: 33% by weight) The resulting thermal transfer recording medium was transferred to a commercially available high-speed printer (2
12 dots to 4 dot serial, applied energy: 25mJ
The alphabet was transferred onto copy paper (Beck smoothness: 20 seconds), and the print quality and dot reproducibility of the resulting printed images were evaluated.

The results are shown in Table 1.

In addition, the said evaluation was performed as follows.

Printing is performed under the condition of a printer's platen pressure of 35 (l g/8) r, and the print quality of the obtained print image is observed, and the presence or absence of surface peeling of the thermal transfer recording medium after printing is observed. The dot reproducibility was evaluated.

In Table 1, the meanings of the symbols are as follows.

"Yoko" L point @... No voids or scratches, and excellent edge sharpness.

O... There are no voids or stains.

Δ: There are some voids.

X: There are many voids and the characters are difficult to read.

common! ”1 disaster O......1 dot is reproduced.

×: One dot is not reproduced, a series of dots, or missing dots occur.

(Comparative Example 1) A thermal transfer recording medium was prepared by providing only the same heat-fusible layer as in Example 1 on the same support as in Example 1, and the print quality and dot reproducibility were the same as in Example 1. We conducted an evaluation.

The results are shown in Table 1.

(Comparative Example 2) A thermal transfer recording medium was prepared in the same manner as in Example 1, except that the surface of the heat-fusible layer in Example 1 was smoothed with a smoother to set Ra to 0.2. Print quality and dot reproducibility were evaluated in the same manner as in Example 1.

The results are shown in Table 1.

Table 1 (Evaluation) As is clear from Table 1, the thermal transfer recording medium of the present invention has excellent dot reproducibility and fixing performance even on transfer media with low surface smoothness such as Lancaster paper. It was confirmed that it was possible to form a printed image with good print quality.

[Effects of the Invention] According to the present invention, (1) Since the heat-melting layer and the heat-softening layer formed on the support are bonded to each other on the uneven surface, the heat-melting layer is bonded to the heat-melting layer from the heat-melting layer. No surface peeling.

Advantages include being able to form printed images with excellent dot reproducibility, and (2) being able to form high-quality printed images with excellent fixability even on transfer media with low surface smoothness. It is possible to provide a thermal transfer recording medium having the following.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view illustrating the cross section of the thermal transfer recording medium of the present invention, and also illustrating the positions where the heat-fusible layer and the heat-softening layer heated by the dots of the thermal head break. 111...Support, 2...Thermofusible layer, No. 3...Thermosoftening layer, 4...Convex portion, 5...Concave portion, 6...-Dot

Claims (2)

[Claims] (1) A heat-softening layer is provided on a support via a heat-melting layer, and the contact surface between the heat-melting layer and the heat-melting layer is an uneven surface, and at least the heat-melting 1. A heat-sensitive transfer recording medium, comprising a coloring material in either the heat-softening layer or the heat-softening layer. (2) The contact surface has an average surface roughness of 0.3 to 1.5.
The thermal transfer recording medium according to claim 1.