JPS60212391A - Thermal transfer material - Google Patents

Abstract

PURPOSE:To provide a thermal transfer material suitable even for a recording material poor in surface smoothness, wherein a thermally transferrable ink layer consisting of the first ink layer comprising a heat-fusible binder or the like and the second ink layer comprising a microencapsulated ink dispersed therein (in this order from the base side) is provided on a base. CONSTITUTION:The thermally transferrable ink layer 3 consists of the first ink layer 4 obtained by mixing a coloring agent (e.g., carbon black) and a heat-fusible binder (e.g., carnauba wax) and having melting or softening point of 50- 120 deg.C and the second layer 5 obtained by dispersing in a binder 7 microcapsules 6 in which an ink comprising a coloring agent and a dispersant or solvent (e.g., animal or vegetable oil or fat) and having a melting or softening point of not higher than 60 deg.C is enclosed in capsule walls of a thermoplastic resin. The ink layer 3 is provided on a base (e.g., a plastic film) 2 by sequential coating to obtain the objective thermal transfer material 1. EFFECT:Printing of broken images or blurring will not occur even on a recording medium poor in surface smoothness, and printed images have excellent fretting resistance.

Description

[Detailed description of the invention] Seed beard spots! The present invention relates to a thermal transfer material that provides a transferred recorded image of good print quality even on a recording medium with poor surface smoothness.

In recent years, with the rapid development of the information industry, various information processing systems have been developed, and recording methods and devices suitable for each information processing system have also been developed and adopted. One such recording method is the thermal recording method.
The equipment used is lightweight, compact, noiseless, and has excellent operability and maintainability, and has recently been widely used.

However, among the recording papers used in thermal recording methods, ordinary thermal recording paper is a color-forming processed paper containing a color former and a color developer, so it is expensive, and records can be tampered with. The paper developed color easily when exposed to heat or organic solvents. However, it has the disadvantage of poor storage stability, such as the recorded image fading in a relatively short period of time.

A thermal transfer recording method has recently been attracting particular attention as a method that maintains the advantages of the above-mentioned thermal recording method and compensates for the drawbacks associated with the use of thermal recording paper.

This heat-sensitive transfer recording method generally uses a heat-sensitive transfer material made by melt-coating a heat-transferable ink made of a heat-melting binder with a colorant dispersed on a sheet-like support. The thermally transferable ink layer is superimposed on the recording medium so as to be in contact with the recording medium, and heat is supplied from the support side of the thermal transfer material by a thermal head to transfer the melted ink layer onto the recording medium. A transfer ink image is formed according to the shape of heat supply. According to this method, it is possible to maintain the above-mentioned advantages of the thermal recording method, use plain paper as a recording medium, and eliminate the above-described disadvantages associated with the use of thermal recording paper.

However, conventional thermal transfer recording methods are not without drawbacks. The reason is that in conventional thermal transfer recording methods, the transfer recording performance, that is, the printing quality, is greatly affected by the surface smoothness. Good printing is performed on highly smooth recording media, but when recording media with low smoothness are used, This means that the print quality deteriorates significantly. However, even when using paper, which is the most typical recording medium, highly smooth paper is rather special, and ordinary paper has various degrees of unevenness due to entangled fibers. Therefore, in the case of paper with large surface irregularities, the hot-melted ink cannot penetrate into the fibers of the paper during printing and only adheres to the convexities on the surface or the vicinity thereof, resulting in sharp edges of the printed image. The image may be missing, or part of the image may be missing, resulting in a decrease in print quality. Additionally, in order to improve printing quality, it is possible to use a heat-melting binder with a low melting point.
In this case, the thermal transfer ink layer becomes sticky even at relatively low temperatures, resulting in disadvantages such as decreased storage stability and staining of non-printed areas of the recording medium.

The main object of the present invention is to eliminate the drawbacks of the conventional thermal transfer recording methods mentioned above, maintain various thermal transfer performances, and -1.
It is an object of the present invention to provide a heat-sensitive transfer material that can give high-quality prints not only to recording media with good surface smoothness but also to recording media with poor surface smoothness.

According to the research of the present inventor, in order to achieve the above object,
The heat-transferable ink layer has a multilayer structure, with a second ink layer in which microencapsulated low-melting point or permeable ink is dispersed on the recording medium side, and a heat-melting second ink layer made of a relatively low-melting-point binder on the support side. It has been found that it is extremely effective to use a thermal transfer material with one ink layer. That is, when the heat-sensitive transfer material thus formed is laminated with a recording medium via the heat-transferable ink layer, and the heat-transferable ink layer is heated in a pattern from the support side, the first
The heat-melting binder of the ink layer melts or softens and is transferred to the recording medium together with the second ink layer, and the second ink layer is transferred to the recording medium together with the second ink layer.
The penetrating ink released by the destruction of the microcapsules in the ink layer penetrates into the structure of the recording medium. As a result of these actions, it is possible to prevent defects in printed images even on recording media with poor surface smoothness, and to improve printing quality.

The heat-sensitive transfer material of the present invention is based on such knowledge, and more specifically, the heat-transferable ink layer is formed on a support, and the heat-transferable ink layer is coated with a colorant in order from the support side. The first ink layer has a melting point or softening point of 50 to 12θ°C, which is made of a heat-melting binder, and the ink has a melting point or softening point of 60°C or less, which is made of a colorant and a dispersion medium or a solvent. It is characterized by having a laminated structure consisting of a second ink layer formed by dispersing microcapsules contained therein in a binder.

Hereinafter, the present invention will be described in further detail with reference to the drawings as necessary. “%” indicates quantitative ratio in the following descriptions.
"and 1 part" are based on weight unless otherwise specified. FIG. 1 is a schematic cross-sectional view in the thickness direction of one example of the most basic thermal transfer material of the present invention. That is, the heat-sensitive transfer material 1 is formed by forming a heat-transferable ink layer 3 on a support 2 that is usually in the form of a sheet (used to include a film).

As the support 2, conventionally known films and papers can be used as they are, such as films of relatively heat-resistant plastics such as polyester, polycarbonate, triacetylcellulose, nylon, and polyimide, cellophane, or sulfuric acid. 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 for example, a heat source such as a laser beam that can selectively heat the thermal transferable ink layer is used. There are no particular restrictions when doing so. In addition, when using a thermal head, a heat-resistant protective layer made of silicone resin, fluororesin, polyimide resin, epoxy resin, phenol resin, melamine resin, nitrocellulose, etc. should be provided on the surface of the support that comes into contact with the thermal head. The heat resistance of the support can be improved by
Alternatively, support materials that could not be used conventionally can also be used.

The thermally transferable ink layer 3 consists of, in order from the support side, a thermally meltable first ink layer 4 and a second ink layer 5 in which microencapsulated ink is dispersed.

The first ink layer 4 is made by dissolving or dispersing a coloring agent in a heat-melting binder. Examples of the heat-melting binder include natural waxes such as wood wax, spermaceti wax, and carnauba wax; Synthetic waxes such as crystalline wax, oxidized wax, ester wax, and low molecular weight polyethylene: myristic acid, lauric acid, stearic acid, behenic acid, palmitic acid, aluminum stearate, lead stearate, barium stearate, zinc stearate, palmitin. Higher fatty acids or their metal salts such as acid zinc, methyl hydroxystearate, glycerol monohydroxystearate, etc.
Derivatives such as esters: Higher alcohols such as stearyl alcohol and behenyl alcohol; Esters such as fatty acid esters of sucrose and fatty acid esters of sorbitan; Others: polyamide resins, polyester resins, epoxy resins, polyurethane resins, acrylic resins , vinyl chloride resin, vinyl acetate resin, cellulose resin, polyvinyl alcohol resin, petroleum resin, phenol resin, styrene resin, etc. may be used alone or in combination of two or more. In addition, to the extent that the melting point or softening point of the first ink layer does not deviate from the range of 50 to 120°C,
Animal and vegetable oils, mineral oils, which are liquid at room temperature, or lanolin, which is semisolid at room temperature, may be used in combination.

Coloring agents include carbon black, nigroshi/dye,
Lamp Black, Sudan Black SM, Alkaline Blue, First Yellow G1 Benjidine Fist Yellow, Pigmen 1・
Yellow, India First Orange, Irgazine Red, Paranitroaniline Medium Red, Toluidine Red, Carmine FB, Permanent Bordeaux FRR, Pigment Orange R1 Lysol Red 2G, Lake Red C, Rhodamine FB, Rhodamine B Lake, Methyl Violet B Lake, Phthalocyanine Blue,
Pigment Blue, Prilliant Green B, Phthalocyanine Green, Oil Yellow GG, Zapon Fist El: I-CGG.

Kayasera) Y963, Kayaset YG, Sumiplast War Yellow G, f Bonfast Orange RR, Oil・
Scarlet, Sumiplast Orange G, Orazole
Brown B1 Pomelo First Scarlet CG, Eye Ink Pillon Red, BEH, Oil Pink OP, Victoria Blue F4. R, First Gen Blue 500
7. All of the various dyes and pigments used in the printing and recording fields, such as Sudan blue and oil peacock blue, can be used.

The proportion of the colorant in the first ink layer 4 is preferably in the range of 1 to 40%.In addition, the first ink layer 4 may contain a surfactant, a filler such as silicon dioxide, etc. as necessary. Attachment,
can be added.

The above-mentioned colorant, hot-melt binder, and other additives added as necessary are mixed using a dispersion machine such as an attritor while heating, and the colorant is dispersed or dissolved in the hot-melt binder. A coating solution obtained by diluting with a solvent or a dispersion medium is applied onto the support z using a hot melt coater or a solvent coater, and is cooled or dried to a thickness of 0.5 to 30 mm. , preferably 1 to lou, is formed.

The second ink layer 5 is formed by dispersing microcapsules 6 containing permeable ink in an inner layer 7.

Penetrating ink consists of a colorant and its dispersion medium or solvent. As the colorant, the same colorant as that used in the first ink layer 4 described above can be used.
Do not necessarily use the same one.1. There's no need to go.

Specific examples of dispersion media or solvents include cottonseed oil, rapeseed oil, camellia oil, castor oil, peanut oil, lanolin, beef tallow, lard, animal and vegetable oils such as whale oil, motor oil, spindle oil, mineral oil such as dynamo oil, vaseline, glycerin, Polyethylene glycol, dioctyl phthalate, monoolein, sorbitan trioleate, etc. (11), waxes and higher fatty acids within the range where the melting point or softening point of the penetrating ink is 60°C or less, l/%J
Other metal salts, derivatives such as esters, thermoplastic resins, etc. can also be used.

To microcapsule a penetrating ink consisting of the colorant and dispersion medium described above, a mixture of these components is obtained, and then dispersed in a solution of wall material resin. Conventional microencapsulation methods such as a method of spray drying a dispersion, a phase separation method, a complex coacervation method, and an interfacial polymerization method are appropriately employed. Further, as the wall material resin, known thermoplastic resins suitable for these microencapsulation methods are appropriately employed.

Microcapsules with a diameter of 0.5 to 20 wells, especially 1
~10 liters can be preferably used, and the volume ratio a of the coating resin and the contained penetrating ink is 10:90 to 70:
A range of 30 is preferable. The proportion of each component in the microcapsules is preferably in the range of 1 to 50% for the colorant and 99 to 50% for the dispersion medium or solvent.

Preferably of such microcapsules 6 it 99
~80%, more preferably 95-85%, preferably 1-20%, more preferably 5-15% binder 7
A coating solution obtained by mixing with
By forming the second ink layer 5 of 30 #L, preferably 2 to 20 #L, the thermal transfer material 1 of the present invention illustrated in FIG. 1 is obtained.

The binder 7 of the second ink layer 5 can be a thermofusible binder similar to the binder of the first ink layer 4, or it can be dissolved in a solvent or water or dispersed in fine particles, and the binder 7 can be dissolved in the first ink layer. Any resinous material can be used as long as it can adhere to the layer. Further, a dispersant, a filler, and an additional coloring agent can also be added to this binder 7 as required.

The planar shape of the thermal transfer material of the present invention is not particularly limited, but it is generally used in the form of a typewriter ribbon or a wide tape used in line printers. Furthermore, for color recording, heat-melting inks of several different tones may be prepared, and these may be applied in stripes or blocks to form a heat-sensitive transfer material.

Next, a thermal transfer recording method using the above-mentioned thermal transfer material 1 will be explained using the most typical thermal head as a heat source. FIG. 2 is a schematic cross-sectional view in the thickness direction of the thermal transfer material showing its outline; that is, the recording medium 8 is brought into close contact with the second ink layer 5 of the thermal transfer material 1, and the back surface of the recording medium is supported by the platen 9. At the same time, thermal pulses are applied by the thermal head 10 to locally heat the ink layer 4.5 in accordance with the desired print or transfer pattern. When the heated portion of the first ink layer 4 rises in temperature and reaches a certain temperature, it softens or melts and is transferred to the recording medium 8 together with the second ink layer 5 which has also softened or melted. At almost the same time, the wall resin of the microcapsules in the second ink layer 5 also softens or melts, destroying the microcapsules and releasing the penetrating ink, which cannot be penetrated by conventional thermal transfer inks due to its penetrating power. The penetrating ink penetrates into the inside of the fiber structure of the recording medium, which would otherwise have been absent, and forms a penetrating ink image 33a. On the other hand, a part of the colored binder of the first ink layer 4 and the second ink layer 5 is mixed with the released permeable ink, and the remaining part covers the permeable recorded image 33a, so that the colored binder as a whole corresponds to the heating pattern. A recorded image 33 with good print quality without defects in the print image can be obtained.

11 Vertical difference 1 As described above in detail, according to the present invention, the thermal transfer ink layer has a multilayer structure, and the second layer in which microencapsulated low melting point or permeable ink is dispersed on the recording medium side.
A heat-sensitive transfer material is provided in which a heat-melting first ink layer made of a binder with a relatively low melting point is disposed on the support side, and by using this, various thermal transfer properties including storage stability of the heat-sensitive transfer material can be improved. By maintaining good performance, it is possible to print without chipping or smearing even on recording media with poor surface smoothness, and even with low softening point or liquid ink at room temperature, printing durability is maintained. It is also possible to record with excellent scratch resistance.

Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

10 parts of carbon black, 15 parts of carnauba wax, 30 parts of ester wax, 45 parts of paraffin wax,
The mixture was melted and kneaded in an attritor heated to 100° C., and carbon black was well dispersed to obtain a hot-melt ink. This ink was hot-melt coated onto a polyethylene terephthalate film having a thickness of 6IL using a Meyer bar to obtain a hot-melt ink layer having a thickness of 2ρ.

Next, 10 parts of carbon black, 25 parts of castor oil, and 5 parts of lecithin were mixed using three rolls to obtain a penetrating ink. 80 g of the above penetrating ink was mixed with 8 g of styrene, 5 g of methyl methacrylate, 6 g of ethyl acrylate, Ig of 2-bitroxyethyl methacrylate, and 0.2 g of benzoyl peroxide. This mixture was emulsified in a 1% aqueous solution of 500 g of polyoxyethylene nonylphenyl ether (50 ethylene oxide molecules adduct) using an ultrasonic emulsifier, heated and polymerized at 75 to 80°C for 4 hours with stirring, and the particle size Microcapsules were centrifuged from the microcapsule dispersion having a microcapsule dispersion of 0.5 to top and dried under reduced pressure to obtain microcapsules.

82 parts of this microcapsule and 8 parts of polyvinyl alcohol
% aqueous solution and mixed with stirring to obtain a coating liquid. This coating liquid was applied onto the heat-melting ink layer using an air knife coater, and dried to form a 12#L heat-sensitive ink layer to obtain a heat-sensitive transfer material.

Example L: 10 parts of carbon black, 15 parts of carbana wax, 30 parts of ester wax, 45 parts of paraffin wax,
The ink was melt-kneaded in an attritor heated to 100°C to disperse carbon black well, and the ink was hot-melt coated onto a 6-t thick polyethylene terephthalate film using a mailer bar. A thermal transfer material having a thermal transfer ink layer with a thickness of 6#L was obtained.

Using the two types of heat-sensitive transfer materials obtained as described above, recording was performed on three types of recording paper having different degrees of smoothness using a commercially available thermal transfer printer, and the results were visually evaluated.The results were as follows.

Example Clear printing Clear printing Comparative example of clear printing
Indistinct Slightly indistinct Clear printing As is clear from the above results, the thermal transfer material of the present invention is a thermal transfer material that does not select the paper quality, and has very little loss of density due to poor smoothness of the recording paper.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view in the thickness direction of an example of the thermal transfer material of the present invention, and FIG. 2 is a thermal transfer showing an embodiment of the thermal transfer recording method of the present invention using the thermal transfer material of FIG. FIG. 3 is a schematic cross-sectional view of the material in the thickness direction. 111 - Thermal transfer material 2...Support 3...Φ Thermal transferable ink layer 4... Heat-melting first ink layer 5 - Second ink layer containing microcapsules 6 - Φ - Permeability Microcapsules 7 containing ink...Thermofusible binder 8...Recording medium 9-Platen 10...Thermal head 33...Ink recorded image (33a e) Penetration part into the inside of the fiber structure ) 1st rl
A

Claims (1)

[Claims] A thermally transferable ink layer is formed on a support, and the thermally transferable ink layer is composed of a colorant and a heat-melting binder in order from the support, and has a melting point or softening point of 50. ~12
A first ink layer having a temperature of 0°C, and a thermoplastic resin containing an ink having a melting point or softening point of 60°C or less made of a colorant and a dispersion medium or a solvent and dispersing microcapsules in a binder. A thermal transfer material having a laminated structure consisting of a second ink layer.