JPH01171984A - Thermal transfer recording medium - Google Patents

Abstract

PURPOSE:To obtain a thermal transfer recording medium being excellent in gradation and especially in reproducibility of a low density part and strongly resistant to mechanical rubbing or the like, by a method wherein a hot-melt ink layer containing wax, a coloring agent and two kinds or more lanolin compounds as main constituents is provided in a construction of fine porosity formed of resin. CONSTITUTION:A hot-melt ink layer containing wax, a coloring agent and two kinds or more lanolin compounds being different in a phase state at a room temperature, as main constituents, is provided in a construction of fine porosity made up of resin and formed on a supporting body. Lanolin compounds being in a state of a solid phase or a semisolid phase at the room temperature are preferably 5-70wt.% of the whole of the lanolin compounds. The coloring agent in hot-melt ink, which is held by a network structure in the construction of fine porisity of resin, is melted together with oil and a hot-melt substance by heating and oozes out of the construction of fine porosity onto an accepting sheet. The amount of the coloring agent that oozes out varies in accordance with the amount of impressed heat energy. By controlling this heat energy, accordingly, the amount of the coloring agent to be transferred can be varied, and an image expressing gradation closely and widely can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heat-sensitive recording medium to which a recorded image is transferred by heating.

[Prior Art] Conventionally, as a heat-sensitive transfer recording medium capable of recording gradation, oil, a heat-fusible substance that is solid at room temperature, and a coloring agent are contained in a microporous structure made of resin formed on a support. A thermal transfer recording medium provided with an ink layer containing as a main component is known. Recently, in order to obtain even higher image quality, that is, to improve reproducibility in low density areas,
Hot melt inks and the like have been proposed that contain a significant amount of oil with a viscosity of 0.00 cps or less. That is, the aim is to improve the reproducibility of low-density areas by reducing the viscosity change of the hot-melt ink.

However, even if the ink components are contained in the microporous structure of the resin, if the viscosity of the ink components is too low, the back side of the sheet
In other words, if you rub with your fingernail or the like from the opposite side of the ink layer, the ink will be transferred to the paper. In addition, the surface of the thermal head is not smooth and has minute protrusions here and there. As a result, the ink layer and image-receiving paper are rubbed, sometimes causing background smudges. this is,
This means that as the viscosity of hot-melt ink has decreased, mechanical margin has been reduced.

In order to solve this problem, the content of oil with a viscosity of 300 cps or less at 25° C. may be reduced, but there is a problem that this does not improve the reproducibility in the low concentration range.

[Objective] The present invention is intended to solve the above problems, and aims to provide a thermal transfer recording medium that has excellent gradation, particularly reproducibility in low-density areas, and is resistant to mechanical abrasion. It is.

[Structure] In order to solve the above problems, the present invention has a microporous structure made of resin formed on a support, and a wax selected from vegetable waxes, mineral waxes, petroleum waxes, and synthetic waxes, and colored waxes. The phase state at room temperature is different.
The present invention provides a heat-sensitive transfer recording medium characterized by being provided with a heat-melting ink layer containing as a main component one or more lanolin compounds.

In the present invention, the lanolin compound in a solid or semi-solid state at room temperature preferably accounts for 5 to 70% by weight of the total lanolin compound.

In the present invention, the colorant in the hot melt ink is retained by the network structure in the microporous structure of the resin. This colorant is heated with a thermal head etc. to produce oil.
It melts together with the heat-melting substance, oozes out from the microporous structure of the resin, and oozes out little by little onto the receiving sheet. The amount of colorant that oozes out varies depending on the amount of heat energy applied by a thermal head or the like. Therefore,
By controlling this applied thermal energy,
It is possible to change the matrix of the colorant to be transferred, and it is possible to produce images with faithful and wide gradation.

The lanolin compound used in the present invention has low compatibility with the resin forming the microporous resin, and is uniformly dispersed in the resin to form the microporous structure. At this time, by using two or more types of lanolin compounds with different phase states at room temperature, that is, by using relatively "hard" lanolin compounds with the same phase or semi-solid phase, the network structure of the resin is formed together with the heat-melting substance. The ink layer itself becomes solid at room temperature by being retained together with the colorant in the liquid phase, and the "soft" lanolin compound in the liquid phase lowers the viscosity of the ink components in the molten state, resulting in low density reproducibility. It is thought that an ink layer is formed that has excellent properties and is resistant to mechanical abrasion and the like.

If the lanolin compound, which is in the same phase or semi-solid phase at room temperature, is less than 5% by weight of the total lanolin compound, scumming may occur due to mechanical abrasion, etc. If it exceeds 70% by weight, the reproducibility of low concentrations may deteriorate. Significantly inferior.

As lanolin compounds, there are various lanolin derivatives, and preferred examples include lanolin derivatives such as metal salts of lanolin fatty acids and lanolin fatty acid esters.

The reason why these products produce favorable results is that lanolin fatty acid esters or metal salts have poor compatibility with the above resins, have good dispersion stability, and have excellent wettability with colored substances, which improves printing quality. This is also considered to be because it has good compatibility with solid components in a molten state and can lower the viscosity.

The lanolin fatty acids in the present invention consist of hydroxylated fatty acids having 13 to 33 carbon atoms, iso- and anti-iso fatty acids, etc., and their metal salts include sodium, potassium, calcium, magnesium, barium, zinc, lead, Metal salts such as manganese, iron, nickel, cobalt, aluminum, etc. can be used.

Examples of lanolin fatty acid esters include esters such as methyl:ethyl, butyl, glycerin, pentaerythritol, polypropylene glycol, and trimethylolpropane.

A specific example is Neocoat Kano S-181,0ES-
183, LFC-50) 1, LS-3102) IB
(Yoshikawa Oil Co., Ltd.), etc.

Further, as the oil, a low viscosity oil having a viscosity of 300 cps or less at 25° C. may be added to the raw material.

Examples of the low viscosity oil in the present invention include the following.

■Higher alcohol ester name Fatty acid Viscosity cps/25
℃ HISOR Haccho E = to Ricinoleic acid
53,6// = 5 isooctane l! ! 2
8.8 = 7 persatic acid
12.7 = 10 isostearic acid 24.3
〃=11 stearic acid 20.0=221
2-hydroxystearic acid 51.4# = 101
Cupric acid 22.2 = 105 isooctanoic acid 24.2 = 107 parsatetic acid 36.8 = 108 dimer acid
36.0/, =110 isostearic acid
56. On = 111 stearic acid
36.8, / = 117 oleic acid
80, / =122 12-Hydroxystearic acid paste ■Hydroxy fatty acid ester name Chemical composition Viscosity CpS/2
5°C C0-FA Methyl Methyl Lysyllate 40C
O-FA methyl-〇 Methyl lysyllate (distilled product) 3
0 CO-FA ethyl-〇 Ethyl lysyllate (distilled product)
30 CO-FA Butyl Butyl Stearate 40M
AR methyl acetyl lysyllate 13 BAR methyl acetyl lysyllate 17 ■Others - Name Name Viscosity CpS/25°C Soybean oil 120 Beannut oil
150 liquid paraffin 2
50 Furthermore, the following plasticizers of 300 cps or less may also be mentioned.

That is, dimethyl phthalate, diethyl phthalate,
Dibutyl phthalate, diethyl phthalate, dioctyl phthalate, diisononyl phthalate, diisodecyl phthalate, butylbenzyl phthalate, dilauryl phthalate, dicyclohexyl phthalate, tricresyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, tris(β) -chloroethyl) phosphate, tributoxyethyl phosphate, tris(dichloropropyl) phosphate, tris(β-chloropropyl) phosphate, triphenyl phosphate, octyldiphenyl phosphate, 'tris(isopropylphenyl)
Phosphate, dioctyl adipate, diisononyl adipate, diisodecyl adipate, dialkyl adipate, di(butyl diglycol) adipate, di-2
-ethylhexyl azelate, dibutyl sebacate, dioctyl triethyl citrate, acetyl tributyl citrate, dibutyl maleate, di-2-ethylhexyl maleate, dibutyl fumarate, butyl oleate, butyl stearate, and the like.

As the support used in the present invention, conventionally known films and papers can be used as they are, such as films of relatively heat-resistant plastics such as polyester, polycarbonate, triacetate cellulose, nylon, and polyimide, cellophane, or Parchment paper or the like can be suitably used. The thickness of the support is preferably about 2 to 15 microns when considering a thermal head as a heat source during thermal transfer, but it is preferable to use a heat source that can selectively heat the thermal transferable ink layer, such as a laser beam, for example. There are no particular restrictions in this case. In addition, when using a thermal head, a heat-resistant protective layer made of silicone resin, fluororesin, polyimide resin, epoxy resin, phenolic resin, melamine resin, nitrocellulose, etc. should be provided on the surface of the support that comes into contact with the thermal head. This makes it possible to improve the heat resistance of the support, or to use a support material that could not be used conventionally.

Further, it can also be used for electrical transfer in which the support is made conductive and a current is applied to the support to generate Joule heat and melt and transfer the ink components.

Although there are no particular limitations on the method for producing the heat-melting ink layer having the above-described structure, the following method is generally used. That is, a wax, a colorant, a lanolin compound, etc. are mixed and dispersed together with a suitable organic solvent using a dispersion device such as an attritor or a ball mill to obtain an ink dispersion (which may also be 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 resulting dispersion is applied onto a support and dried to obtain a hot-melt ink layer having the above-mentioned fine structure. A wetting agent, a dispersant, etc. may be added to the dispersion liquid in order to improve the dispersion of the wax, colorant, and lanolin compound described above. Also, if necessary, fillers commonly used in resin coatings of this type can be added. In relation to the above-mentioned lanolin compounds, 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 Thermoplastic resins such as single or copolymers of seven polymers selected from methacrylic acid esters, phenol, furan, formaldehyde, urea, melamine, alkyd, unsaturated polyesters,
It is preferable to use a thermosetting resin such as epoxy.

Alternatively, a substance that is incompatible with the resin that forms the porous structure and soluble in a solvent that does not dissolve the resin is kneaded with the resin, and is coated on the support to form a resin layer. A transfer layer having the above-described structure can also be obtained by dissolving a substance in the above-mentioned solvent to form a porous resin structure, and then filling the porous structure with a thermally transferable ink.

Examples of the coloring agent include colored dyes and colored pigments, but dyes can provide images with more preferable gradation.

Examples of such dyes include the following direct dyes, acid dyes, basic dyes, mordant dyes, sulfur dyes, vat dyes, azoic dyes, and oil dyes.

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 B1 Victoria blue B, etc.

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

5) @Kasomeri: Sulfur Brilliant Green 4G, etc.

6) Vat dyes: indanthremble, etc.

7) Azoic dye: naphyl As, etc.

8) Oil dye Nigrosin, Spirit Black E8,
Varifast Orange 3206, Oil Black 215
, Butter Yellow, Sudan Blue ■, Oil Red B
, Rhodamine B et al.

9) Disperse dye (9-1> Monoazo disperse dye: Daybirds First Yellow 01 Daybirds First Yellow 5G,
Daybirds First Yellow 5R1 Daybirds Red R etc.

(9-2) Anthraquinone disperse dye: Disbird's First Violet OR1 Disbird's First Violet B1 Disperse Blue Extra, Disbird's First Brilliant Blue B, etc.

(9-3> Nitrodiphenylamine disperse dyes: Disbird's Fast Yellow RR, Disbird's Fast Yellow L, etc.

Among these dyes, those that are difficult to sublimate are preferred.

It is sufficient that the particle size of these dyes is smaller than that of the gradation control agent having a network structure, and it is preferable that the dye be in a dissolved state.

Examples of colored pigments include fine particle pigments (Japanese Patent Application No. 166,020/1982) and monoazo pigments (Japanese Patent Application No. 253,723/1980) which have already been proposed by the present applicant.

Among the waxes used in the present invention, vegetable waxes include carnauba wax, candelilla wax, rice wax, real wax, etc. Mineral waxes include montan wax, osikelite, ceresin, etc., and petroleum waxes include Examples include paraffin wax, microcrystalline wax, petrolactam, etc. Synthetic waxes include synthetic hydrocarbons such as Sasol wax (Fischer-Tropsch wax) and polyethylene wax, montan wax derivatives, paraffin wax derivatives, and microcrystalline wax derivatives. Modified waxes, hydrogenated waxes such as hydrogenated castor oil derivatives, 12-hydroxystearic acid, stearic acid,
Higher fatty acids such as palmitic acid, lauric acid, aluminum stearate, lead stearate, barium stearate, zinc stearate, zinc palmitate, methyl hydroxystearate, glycerol monohydroxystearate, or their metal salts, derivatives such as esters, etc. can be mentioned. These holding materials are used alone or in a mixture of two or more in an amount of 50 to 200 parts by weight based on 100 parts by weight of the thermoplastic resin constituting the thermal transfer layer. In addition, the lanolin compound was added at 20 parts by weight per 100 parts by weight of the retention agent.
It is used in a proportion of ~100 parts by weight.

In addition, in order to more strongly maintain the network structure of the porous resin structure, it is also possible to provide an intermediate adhesive layer on the support in advance.

Examples of the intermediate adhesive layer include so-called plastic resins and plastic resins to which fillers are added.

The receiving sheet may basically be plain paper or synthetic paper, but if necessary, it may be made of the above resins, 1iQz, silica, ZnO.
It is also possible to apply a filler containing fillers such as the like on plain paper to facilitate the transfer of the colorant.

[Example] Next, the present invention will be explained in more detail with reference to Examples.

Note that "parts" and "%" are based on weight.

Example 1 NeOZapOn Blue 807 (manufactured by BASF > 30 parts Lanolin fatty acid calcium salt (semi-solid) 10 parts Modified lanolin oil 0ES-183 (liquid, manufactured by Yoshikawa Oil Co., Ltd. > 2 oats Carnauba wax 30 parts Liquid paraffin
25 parts of the above heat-melted Ishik component was thoroughly dispersed at 68° C. with a mixed solution of 100 parts of methyl ethyl ketone and 150 parts of toluene in a ball mill for about 24 hours.

Next, a 20% reagent cellulose acetate (manufactured by Kanto Chemical Co., Ltd., nibutyl group 37%, melting point 195-205°C) solution (10 parts resin, 20 parts toluene, 100 parts 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 is applied to the surface of a polyester film with a thickness of about 6 μm with a silicone resin heat-resistant layer on the back side using a wire bar, and dried for about 1 minute at a drying temperature of IOO'C to form a heat-melting ink with a thickness of about 5 μm. formed a layer.

The ink layer of the transfer medium thus obtained was stacked so as to face the synthetic paper receiver, and an image was recorded from the back side of the transfer medium using a thermal head with a recording density of 6 dots/mm by varying the heating energy. As a result, a cyan tone characteristic curve as shown in FIG. 1 was obtained.

Table 1 shows the results when plain paper and thermal transfer recording paper were placed facing each other and rubbed with a fingernail from the back side.

Comparative Example 1 Neozapon Blue 807 (manufactured by BASF) 30 parts modified lanolin oil 0ES-18
3 (liquid, manufactured by Yoshikawa Oil Co., Ltd.) 30 parts carnauba wax 30 parts liquid paraffin 25 parts The above heat-melting ink components were dispersed in the same manner as in Example 1, and dispersed in the same resin solution as in Example 1. The ink was applied to a still film and dried to form a heat-melting ink layer with a thickness of about 5 μm. The gradation characteristic curve of this ink sheet and the results regarding freezing are shown in FIG. 2 and Table 1.

Example 2 Neozapon Blue 807 (manufactured by BASF) 30 parts Lanolin fatty acid barium salt (solid) 25 parts Modified lanolin oil 0ES-183 (liquid, manufactured by Yoshikawa Oil Co., Ltd.) 5 parts Carnauba wax 30 parts Liquid paraffin 25 parts The above hot melt ink components A 5 μm thick heat-melting ink layer was formed using the same method as in Example 1, and the same experiment was conducted. The results are shown in FIG. 1 and Table 1.

The results of the high concentration portion of Example 2 were almost the same as those of Example 1 shown in FIG.

Comparative Example 2 Neozapon Blue 807 (manufactured by BASF) 30 parts lanolin fatty acid calcium salt
40 parts carnauba wax 3
0 parts liquid paraffin 15 parts Using the above heat-melting ink components, 5 μm in the same manner as in Example 1.
The same experiment was conducted by forming a heat-melting ink layer, and the results are shown in FIG. 2 and Table 1. Note that the reproducibility of the low concentration portion (density 0.15 or less) when obtaining the plot shown in FIG. 2 was unstable.

[Effect] As is clear from the above explanation, in the recording medium of the present invention, ink oozes out from between the porous resin structures and is transferred to the receiving sheet surface depending on the magnitude of heating energy, so that the ink is transferred to the surface of the receiving sheet. By controlling the heating energy, a transferred image with excellent gradation expression and wide gradation reproduction can be obtained, and it is also resistant to mechanical abrasion. Additionally, full color images can be obtained by selecting various dyes.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between applied energy and image density in Examples, where curve A shows the results of Example 1 and curve B shows the results of Example 2. FIG. 2 is a graph showing the relationship between applied energy and image density in Comparative Examples, where curve C shows the results of Comparative Example 1, and curved lines show the results of Comparative Example 2.

Claims (2)

[Claims] (1) In a microporous structure made of resin formed on a support, waxes selected from vegetable waxes, mineral waxes, petroleum waxes, and synthetic waxes, a coloring agent, and two or more types having different phase states at room temperature are added. 1. A heat-sensitive transfer recording medium comprising a heat-melting ink layer containing a lanolin compound as a main component. (2) The thermal transfer recording medium according to claim 1, wherein the lanolin compound in a solid or semi-solid state at room temperature accounts for 5 to 70% by weight of the total lanolin compounds.