JPH01146788A - Thermal transfer recording sheet - Google Patents

Abstract

PURPOSE:To enable a high-printing quality and sharp transfer image to be recorded even on a recording medium having a low surface smoothness, by a method wherein, a release layer is made of a hot-melt substance, and the value of critical surface tension of the hot-melt substance is made lower than that of a substrate (20 deg.C). CONSTITUTION:A recording sheet has a two-layer construction wherein a release layer 2 is applied on one surface of a substrate 1 and thereon a hot-melt ink layer 3 is applied. Since the adhesion of the release layer 2 to the hot-melt ink layer 3 is higher than that to the substrate 1, the release layer 2 is separated from the substrate 1 in transferring. The release between the substrate and the release layer depends on the respective values of intrinsic critical surface tension gammac (20 deg.C). Namely, by setting the value of critical surface tension gammac of the release layer to be smaller than that of the substrate, a high-printing quality and sharp transfer image can be obtained even on a paper having a low surface smoothness.

Description

Detailed Description of the Invention (A> Industrial Application Field The present invention relates to a thermal transfer recording sheet. Specifically, the present invention relates to a thermal transfer recording sheet that can record a good transfer image on a recording medium with low surface smoothness. Regarding record sheets.

(E3') Prior Art In recent years, thermal transfer recording, in which a transferred image is formed on plain paper using a thermal printer, thermal facsimile, etc., has been actively developed. This thermal transfer recording is relatively easy to maintain due to its simple device mechanism, and has low price and maintenance costs. It also uses low energy to produce clear and durable recordings, and uses multi-colored ink sheets, making it relatively easy to maintain. It has been widely used recently because color recording is easily possible.

In particular, the amount of monochrome thermal transfer recording sheets used is increasing due to the spread of thermal printers.

When a conventional thermal transfer recording sheet is used, it is suitable for the recording medium to be used, that is, paper commonly called plain paper, that has a high surface smoothness. Paper surface smoothness is usually JIS
BEKK standard defined in P8119 (
seconds), but if expressed in terms of this smoothness, it would be 20
Paper with a time of about 0 seconds is suitable.

However, paper with low surface smoothness, e.g.
When using paper such as second PPC paper, four-frame paper, or bond paper of 10 seconds or less, it is not possible to obtain clear transferred images with high print quality using conventional thermal transfer recording sheets.

There are various known techniques regarding thermal transfer recording sheets compatible with such paper having low surface smoothness.

For example, there is a method of improving the fluidity of hot-melt ink during heating so that it flows into the recesses in the rough surface of plain paper. That is, JP-A-60-161196 discloses a method of adding a high-boiling hydrocarbon solvent or a high-boiling halogenated hydrocarbon solvent to a heat-melting ink.

Another method is to add a thermally decomposable foaming agent to the heat-melting ink and cause the ink to adhere to or penetrate into the recesses of the rough surface of plain paper by the pressure of the gas generated during transfer. That is, Japanese Patent Application Laid-Open No. 59-201893 discloses a method of adding an inorganic compound such as bicarbonate, carbonate, or nitrite, or a nitroso-based or sulfonyl hydrazide-based organic compound to a substance that decomposes when heated. ing.

Furthermore, the transfer layer has a two-layer structure, with an intermediate layer that does not contain a colorant on the surface close to the base material, and a hot-melt ink on top of it, so that the transfer after heating can be applied to the protrusions on the rough surface. There is a way to build bridges. That is, JP-A-62-
9991 discloses a method using a supercooling material such as dicyclohexyl phthalate, benzotriazole, acetanilide, etc. as an intermediate layer.

(C) Problems to be Solved by the Invention The patent publications cited in the above-mentioned prior art have various problems.

For example, hot-melt ink that improves fluidity improves transferability, but there is a problem in that the transferred image becomes smeared due to friction or rubbing during handling.

Furthermore, in the method of adding a thermally decomposable foaming agent, it is difficult to find suitable transfer conditions and the amount of sul gas generated during transfer is small. This is particularly undesirable when applying hot-melt ink to a substrate.

Broadly speaking, a method in which the transfer layer has a two-layer structure is suitable for transferring to the target recording medium with low surface smoothness, but it is limited to materials that have a suitable melting point and supercooling properties. be.

(D> Means for Solving the Problems The present invention provides a thermal transfer recording sheet that solves the conventional drawbacks and can record clear transfer images with high print quality even on recording media with low surface smoothness. This is what we provide.

That is, the thermal transfer recording sheet provided by the present invention is
In a thermal transfer recording sheet formed by sequentially coating a release layer and a heat-melt ink layer on a base material, the release layer is made of a heat-melt material, and the critical surface tension γc value of the heat-melt material is
20°C) is lower than the critical surface tension γc value (20°C) of the base material.

Further, when the base material is a polyester film, the critical surface tension γc value of the present invention is 4 Q dyne/Cm or less.

Furthermore, when the base material is a polyethylene film, the critical surface tensile cuff C value of the present invention is 30 dyne/cm or less.

The present invention will be explained in detail below.

The thermal transfer recording sheet of the present invention has a two-layer structure in which a release layer is coated on one side of a base material, and a heat-melting 11129 layer is further coated thereon. By overlapping the heat-melting ink layer side of the base material with plain paper and heating printing using a thermal head from the opposite side of the base material, a printed image can be obtained by transfer onto the plain paper surface. In this case, the printed image is one in which both the release layer and the hot-melt ink are transferred from the base material. In other words,
The adhesiveness of the Type 1 layer is higher with the hot-melt ink layer than with the substrate, and therefore it will peel off from the substrate. As described above, in the thermal transfer recording sheet of the present invention, both the release layer and the heat-melting ink layer are peeled off from the base material and transferred to plain paper, thereby printing on plain paper, especially paper with low surface smoothness. This has the purpose and effect of obtaining a high quality and clear transferred image.

That is, an object of the present invention is to peel both the release layer and the heat-melt ink layer from the base material.

The release layer in contact with the base material is easily transferred to plain paper along with the heat-melting ink due to the heat from the thermal head.

This makes it possible to produce clear transferred images even on paper with low surface smoothness.

The thermal transfer recording sheet of the present invention is overlaid with plain paper and printed by a thermal head under heat to form a transfer image on the plain paper together with the release layer, but the heat-melting ink melts upon heating and penetrates into the rough surface of the plain paper. Or, it adheres and the associated release layer is transferred along with the ink.

At this time, it is thought that the release layer imparts sharpness to the print by creating a m2 gap across the valleys in the uneven portions of the rough surface. However, fundamentally, the release layer has low adhesion to the base material, so it is thought that it is easily peeled off from the base material by heating printing with a thermal head.

As described above, in the present invention, the peeling between the base material and the release layer is determined by the respective specific critical surface tension γc value (20°C
) and found that it depends on the γc value. That is, the object of the present invention is achieved by making the critical surface tension γc value of the release layer smaller than the critical surface tension γc value of the base material. The larger the difference in the critical surface tension γc values, the smaller the critical surface tension rC value of the release layer, which also means that the surface energy of the release layer becomes smaller. Also, from the viewpoint of adhesiveness,
Culms with low surface energy also have low adhesion. In other words, if the critical surface tension γc of the release layer is smaller than the critical surface tension γc of the base material, the adhesion to the base material will be weaker.

On the contrary, low adhesion is nothing but an improvement in the transferability of the present invention. Based on these reasons, the thermal transfer recording sheet of the present invention is capable of producing a clear transfer image with high print quality on the target paper with low surface smoothness.

Next, the materials used will be explained in detail.

The base material may be thin paper such as capacitor paper, typewriter paper, tracing paper, synthetic paper, cellophane paper, or synthetic resin film such as polyester film, polyimide film, polyethylene film, polycarbonate film, Teflon film, etc. It is used after being heat-resistant treated to prevent it from sticking to the thermal head.

Among these examples, polynisder film (critical surface tension γc=43 dyne/
cm ) and polyethylene film (same, 3 i dy
ne/cm) is preferred.

Examples of materials used for the release layer of the present invention include synthetic resins. For example, polyvinylidene chloride (critical surface tension γc = 40 dync/ci>), polystyrene (
same, 33-43 dyne/cm), polyvinyl chloride (
39 dyne/cm'), polyethylene (39 dyne/cm'),
31 dyne/cm), polyisobutylene (31 dyne/cm)
0dyne/cm) Polyvinyl alcohol (37d
polymethyl methacrylate (36 dyne/cm ), polymethyl methacrylate (31.5 c+yne/cm ), etc.
, polybutyl acrylate (same, 29dyne/Cm
), itc') to*shi)Lt7ri') L/-t (same, 27.5 dyne/cm) polyoctyla'
)') Rate (same, 23.5 dine/cm)
, polylauryl acrylate (same, 21.3 din
e/cm), polystearyl acrylate (same,
Examples include polyalkyl acrylates such as 20.8 dyne/cm ) and polyoctadecyl acrylate (20 dyne/cm ). moreover,
For example, heat-melting substances such as waxes may be used within the scope of the present invention. Moreover, there is no limitation in any way whether they are used alone or in combination.

The release layer of the present invention can be applied to a substrate using the above-mentioned materials as an aqueous system, a solvent system, or a hot melt, but any coating or printing method may be used. The coating thickness of the release layer is 0.25 to 10 tan, preferably 0.5 to 5/#7
+, more preferably 1 to 3 IJfn.

The ink used in the heat-fusible ink layer of the present invention is composed of a heat-fusible substance, a colorant, a binder, a softener, etc., which can be used as required.

Typical examples of heat-melting substances are listed below.
It is not limited to these.

Examples of waxes include vegetable waxes such as rice wax, real wax, candelilla wax, and carnauba wax, animal waxes such as lanolin, beeswax, spermaceti wax, and selax wax, montan wax, osikerite, and ceresin. Petroleum waxes such as mineral waxes, paraffin waxes, and microcrystalline waxes,
Oxidized paraffin wax, synthetic hydrocarbon waxes such as low-molecular polyethylene, fatty acid amide waxes such as ricinoleamide, lauric acid amide, erucic acid amide, palmitic acid amide, oleic acid amide, stearic acid amide, and ethylene bisstearic acid amide. can be mentioned.

Examples of metal salts include metal salts of higher fatty acids such as sodium stearate, sodium palmitate, potassium laurate, potassium millispoonate, sodium stearate, zinc stearate, aluminum stearate, and magnesium stearate. be able to.

Examples of resins include polyamide resins, polyester resins, epoxy resins, polyruthane resins, polyacrylic resins, polyvinyl resins, polyvinyl chloride resins, cellulose resins, polyvinyl alcohol resins, petroleum resins, Examples include terpene resins, borisdyrene resins, polyolefin resins, and elastomers.

Coloring agents include dyes and pigments such as water-soluble dyes, oil-soluble dyes, disperse dyes, and colored pigments, which can be used depending on the need.

Specific examples will be given below, but the invention is not limited to these, and two or more types may be used in combination.

Water-soluble dyes include nitroso dyes, azo dyes (mono,
(bis, tris, tetrakisazo dye), stilbene azo dye, ketoimine (diphenylmethane) dye, triphenylmethane dye, xanthene dye, acridine dye, quinoline dye, methine uncut, polymethine dye 1, deazole dye, indamine dye 1, Examples of the dyes include azine dyes, thiazine dyes, Axike]・N dyes 1'E+, anthraquinone dyes, and phthalocyanine dyes 1.

As oil-soluble dyes, azo dyes, azo metal salt dyes 141
, anthraquinone dyes, and phthalocyanine dyes. To give a more specific example, the azo dyeing agent is Solvent Yellow 2 (C, 1, 11020
, C and I are in parentheses below.

No) Solvent Orange 1 (11920),
Turben 1 to Red 2/1 (26105>, Solvent Brown 3 (113 (30), etc.), Solvent Yellow 19 (1,39QOA), etc. as azo metal complex dyes.
>, Solvent Orange 5 (18745A>, Turben 1 to Red 8 (12,715,), Solvent Brown 37, Solvent Black 123 (12195)
Anthraquinone dyes include Solvent Violet 13 (60725) and Solvent Blue 11.
(61525), Solvent Green 3 (6156)
5), and examples of phthalocyanine dyes include Solvent Blue 25 (74350).

Examples of disperse dyes include aminoazo or aminoanthraquinone dyes, nidroarylamine dye E, and the like. To give a more specific example, the aminoazo dye is Disverse Yellow 3 (C, 1, 11855, hereinafter C, I in parentheses).

(indicates No), Disbirds Orange 3 (11005)
, Disbird's Red 1 (11110), Disbird's Violet 24 (112,00>, Disbird's Blue 44, etc.). Aminoanthraquinone dyes include Disbird's Orange 11 (60700), Disbird's Red 4 (60755), Disbird's Violet 1 (61100), Disperse Blue 3 (
61!5. ．． 05> etc.

Nidroarylamine dyes include Disperse Yellow 1 (10345) and 42 (10338).

Colored pigments include azo pigments (monoazo, bisazo, condensed azo pigments), dyeing lake pigments (acid dye lake, salt dye lake, mordant dye lake pigment), 21 to 2 pigments,
Examples include nitroso pigments, phthalocyanine pigments, high grade pigments F4 (vat dye type pigments 1, metalworking 11 salt pigments, perylene pigments, isoindolinone pigments, quinacridone pigments).More specific examples include: Examples of azo pigments include Hansa Yellow G (C, 1, 11680, hereinafter C, 1, Nσ is shown in parentheses), Hansa Yellow R (12
710), Pyrazolone Red B (21120>, Permanent Red R (12085), Lake Red C (1
5585), Brillian 1 to Carmine 6B (15850
), Permanent Emine FB (12490) (monoazo pigments), Benzidine Yellow G (21090>, Benzidine Yellow GR (21100>), Permanent Yellow NCR (20040> (bisazo pigments), Chromophthal Yellow, Chromophthal Red (mono azo pigments) Dyeing lake pigments include quinoline yellow lake (47005) and eosin lake (453
80), Alkaline Blue Lake (42750A, 42
770A> (all acid dye lake pigments), Rhodamine Lake B (45170), Methyl Violet Lake (42535), Victoria Blue Lake (44045)
), malachite green lake (42,000) (all basic dye lake pigments), alizarin lake (58,000)
) (mordant dye lake pigment). Nitro pigments include Naphthol Yellow 5 (10316), nitroso pigments include Pigment Green B (10,006) and Naphthol Green B (19020>), and phthalocyanine pigments include Metal-Free Phthalocyanine Blue (74100).
, phthalocyanine blue (74160), and phthalocyanine green (74260). Highly treated faces include Anthrapyrimidine Yellow (68420) and Indanthrene Brilliant Orange GK (59305).
, Industhrene Blue R3 (69800), Thioindigo Red B (73300) (vat dye pigments),
Nickel Azo Yellow (12775) Umbrella FK♀11 salt pigment), Perylene Red (717140), Perylene Scarlet (71137) (perylene pigment), Isoindolinone Yellow (isoindolinone pigment), Quinacridone Red Y (46500), Quinacridone Magenta (
73915).

In addition, carbon black (C) is used as a black pigment.

r, 77265. ).

As the binder, either a water-soluble binder or a water-insoluble binder can be used.

Specific examples of such binders are illustrated below, but the binder is not limited to these, and two or more types may be used.

As the binder, for example, polyvinyl alcohol,
Methylcellulose, birabun hydroxyedil 1? /Rerose, carboxymethylcellulose gum arabic, starch and its constituents, casein, polyvinylpyrrolidone,
Butyral resin, ethylene ethyl acrylate, styrene-butadiene copolymer, vinyl acetate resin, vinyl acetate copolymer, acrylic resin, methyl methacrylic resin,
Examples include styrene-acrylonitrile resin, ethylene-vinyl acetate copolymer, polyester resin, petroleum resin, and the like.

Examples of softeners include mineral oil, dibutyl phthalate, dioctyl phthalate, mineral spirit, liquid paraffin, and the like.

In addition to the heat-melting substances, colorants, binders, and softeners listed above, additives such as surfactants, dispersants, antistatic agents, antioxidants, and ultraviolet absorbers may be added.

Coating machines used for coating the mold release layer and heat-melting ink layer of the present invention on the base are known coating machines such as Hola 1 to melt coater, air knife coater, roll coater, blade coater, bar coater, etc. A coater, or a known printing machine using a flexo method, a gravure method, etc. may also be used.

Note that solvent coating can be carried out using general solvents, such as methanol, ethanol, isopropyl alcohol, toluene, methyl ethyl ketone, acetone, ethyl acetate, etc., as appropriate.

(E) Function The thermal transfer recording sheet of the present invention is formed by sequentially coating a release layer and a heat-melting ink layer on one side of a base material. The release layer is made of a heat-fusible substance, and the heat-fusible substance is characterized in that it has a value lower than the critical surface tension γc value (20° C.) of the base material.

The thermal transfer recording sheet of the present invention having such characteristics is as follows:
'High print quality on recording media with low surface smoothness,
It has the ability to produce 17 clear transferred images.

Furthermore, in the thermal transfer recording sheet of the present invention, the release layer and the heat-melt ink layer are both transferred during heating printing by the thermal head, so the heat-melt ink transferred onto the recording medium is covered by the release layer. This has the effect of making it possible to transfer images with wear resistance by 1q.

Hereinafter, the present invention will be specifically explained with reference to Examples. In addition, "1 part" in the examples indicates small parts.

(F) Examples Example 1 The uncoated surface of a 6-cm thick polyester film coated with a heat-resistant treatment layer (critical surface tension γc = 43 dyne/c)
M) was coated with a release layer made of a heat-fusible substance to a coating thickness of 2 cm using a roll coater.

Critical surface tension γc = 36dyn as a thermofusible substance
An aqueous emulsion of polymethyl methacrylate of e/cm was used. Subsequently, a heat-melt ink layer was coated on the release layer using a hot-melt coater using a heat-melt ink having the following formulation to a coating thickness of 4p to obtain a thermal transfer recording sheet.

Carbon black 15 parts Ethylene-vinyl acetate copolymer 10 parts Carnauba wax
30 parts 150'F paraffin wax 40
5 parts petroleum resin (m, I) (85°C) 5 parts The thermal transfer recording sheet thus obtained was shaped into a ribbon and transferred to a commercially available bond paper (Mitsubishi Paper Mills, Spica Bond Paper) with a surface smoothness of 10 seconds. When printed using a printer (Typester 5, manufactured by Canon), a clear and abrasion-resistant transfer image 8- could be obtained on bond paper.

Comparative Example 1 The release layer in Example 1 was wiped off and only the heat-melting ink layer was applied to obtain a thermal transfer recording sheet, and printing was performed in the same manner as in Example 1. As a result, in the transferred image, the concave portions of the rough surface remained white and unprinted areas remained, making it impossible to obtain a fine transferred image. Further, when the transferred image was rubbed with a finger, it became smeared and its abrasion resistance was insufficient.

Example 2 Polyvinyl alcohol (critical surface tension γc = 37) was used instead of polymethyl methacrylate used in Example 1.
A thermal transfer recording sheet was obtained in the same manner as in Example 1 except that dyne/cm) was used.

When printing was carried out in the same manner as in Example 1, a clear and abrasion-resistant transferred image was obtained.

Example 3 Polyethylene film with a thickness of 10 In (critical surface tension T
c = 31 dyne/cm) and the heat-fusible material polyoctadecyl acrylate (critical surface tension γc =
The release layer material consisting of 20 dyne/cm) was coated with a hot melt coater to a coating thickness of 11! It was coated so that it became m. Subsequently, the hot-melt ink used in Example 1 was applied onto the release layer using a hot-melt coater to a coating thickness of 4Ia to obtain a thermal transfer recording sheet.

The thus obtained thermal transfer recording sheet was transferred to a surface smoothness of 1 using a commercially available facsimile machine (manufactured by Oki Electric, 0F-101).
When printed on 0-second bond paper (Mitsubishi Paper Mills, Spica Bond paper), a clear and wear-resistant transfer image was obtained.

Comparative Example 2 A thermal transfer recording sheet No. 17 was prepared in the same manner as in Example 3 except that the release layer was removed.

When rough printing was performed in the same manner as in Example 3, the transferred image remained unprinted, was white, and lacked sharpness.

Furthermore, the abrasion resistance of the transferred image was poor and staining occurred.

(G) Effects of the Invention As described above, the thermal transfer recording sheet of the present invention is capable of producing 1q of clear transferred images with high print quality on paper with low surface smoothness, and furthermore has abrasion resistance. The thermal transfer recording sheet of the present invention is of extremely high industrial significance because it is capable of transferring transferred images (7).

[Brief explanation of the drawing]

FIGS. 1 and 2 are diagrams showing the structure of a thermal transfer recording sheet according to the present invention. In addition, in Figure 1, heat-resistant treatment 1! f! FIG. 3 is a configuration diagram in which the layer is provided on the opposite side from the heat-fusible ink layer;
FIG. 2 is a structural diagram without the heat-resistant treatment layer.

Claims (1)

[Scope of Claims] 1. A thermal transfer recording sheet formed by sequentially coating a release layer and a heat-melt ink layer on a base material, wherein the release layer is made of a heat-melt material, and the heat-melt material is made of a heat-melt material. The critical surface tension γc of
The value (20℃) is the critical surface tension γc value (20℃) of the base material.
) A thermal transfer recording sheet characterized by a lower value. 2. The thermal transfer recording sheet according to claim 1, wherein when the base material is a polyester film, the critical surface tension γc value of the heat-fusible substance is 40 dyn/cm or less. 3. The thermal transfer recording sheet according to claim 1, wherein when the base material is a polyethylene film, the critical surface tension γc of the heat-fusible substance is 30 dyne/cm or less.