Heat-sensitive transfer material and heat-sensitive transfer recording method

A heat-sensitive transfer material having a heat-transferable ink layer formed on a support. Said heat-transferable ink layer is constituted of microcapsules dispersed in a heat-fusible binder and enclosing a penetrating ink. Said penetrating ink is constituted of a colorant and an oil agent which is liquid or semi-solid at room temperature. During recording, the ink released from the microcapsules will penetrate into the fibrous structure of the recording paper to give printed letters of good quality even on a recording paper with poor surface smoothness.

BACKGROUND OF THE INVENTION 
This invention relates to a heat-sensitive transfer material which can give 
a transfer-recorded image of good printed letter quality even on a 
recording medium with poor surface smoothness, and to a heat-sensitive 
transfer recording method using the same. 
With rapid progress of information industries in recent years, various 
information processing systems have been developed, and various recording 
methods and devices suited for the respective information processing 
systems have been developed and adopted. As one of such recording methods, 
the heat-sensitive recording method has recently been widely used because 
of various advantages such as that the apparatus therefor is light in 
weight and compact, does not generate noise and also is excellent in 
operability and maintenance. 
However, of the recording papers used for the heat-sensitive recording 
method, ordinary heat-sensitive recording papers are expensive since they 
are converted papers containing a color forming agent and a developing 
agent, and also involve the problems that alteration of the recording is 
possible, that the recording paper is susceptible to color formation by 
heat or organic solvents and that the storability of recording is poor, 
since a recorded image fades within a relatively short time. 
As the method which maintains the advantages of the heat-sensitive 
recording method as described above and also compensates for the 
disadvantages of using heat-sensitive recording papers, the heat-sensitive 
transfer recording method is particularly attracting attention in these 
days. 
In the heat-sensitive recording method, a heat-sensitive transfer material 
is used, which comprises a heat-transferable ink containing a colorant 
dispersed in a heat-fusible binder coated by melting on a support 
generally in the form of a sheet and the recording is generally conducted 
by superposing the heat-sensitive material on a recording medium such as 
paper so that the heat-transferable ink layer will contact the recording 
medium, supplying heat from the support side of the heat-sensitive 
transfer material by means of a thermal head to transfer the molten ink 
layer to the recording medium, thereby forming a transferred ink image 
corresponding to the heat supplying pattern on the recording medium. 
According to this method, the advantages of the heat-sensitive recording 
method as mentioned above can be maintained, and also the disadvantages 
with the use of the heat-sensitive recording paper can be eliminated. 
However, the heat-sensitive transfer recording method of the prior art is 
not free from drawbacks. That is, according to the heat-sensitive transfer 
recording method of the prior art, the transfer recording performance, 
namely the printed letter quality, is remarkably influenced by the surface 
smoothness of the recording medium, and therefore while good printing can 
be effected on a recording medium having high smoothness, the printed 
letter quality will be markedly lowered in the case of a paper with low 
smoothness. However, even when paper which is the most typical recording 
medium may be used, a paper with high smoothness is rather special and 
ordinary papers have surface unevenness to various extents because they 
are formed through entanglements of fibers. Accordingly, in the case of a 
paper with large surface unevenness, the heat-molten ink cannot penetrates 
into fibers during printing but attaches only on the convexities or in the 
vicinity thereof on the surface, as a result of which the printed image 
may not be sharp at the edge portion or a part of the image may be 
missing, lowering the printed letter quality. Also, for improvement of the 
printed letter quality, it may be considered to use a heat-fusible binder 
with a low melting point. In this case, however, the heat transferable ink 
layer becomes tacky also at a relatively lower temperature, whereby 
inconveniences such as lowering in storability and staining at the 
non-printed portion may occur. 
For the purpose of removing inconveniences such as defects or imperfections 
of printed letters without inviting such lowering in storability, the 
amount of heat supplied may be increased and heating time may be 
prolonged. Although imperfection of printed letters may be avoided by 
employment of such measures, lowering in recording sensitivity or in heat 
transfer speed may be caused, and further the printed letters will 
contrariwise become too bold, reducing the clearness of the recorded 
image. 
SUMMARY OF THE INVENTION 
A primary object of the present invention is to provide a heat-sensitive 
transfer material and a heat-sensitive transfer recording method which can 
give printed letters of good quality not only on a recording medium having 
good surface smoothness but also on a recording medium having poor surface 
smoothness, by overcoming the drawbacks of the prior art as described 
above, while maintaining various heat transfer performances. 
According to our study with the above object, it has been found very 
effective to use a heat-sensitive transfer material having a 
microencapsulated ink comprising a colorant and an oil agent which is 
liquid or semi-solid at room temperature and having a property of 
penetrating into fibers dispersed in a heat-meltable binder constituting 
the heat-transferable ink layer. 
Thus, by superposing the thus formed heat-sensitive transfer material with 
its heat-transferable ink layer facing a recording medium and heating the 
heat-transferable ink layer in a desired pattern while applying a pressure 
by means of a platen on the backside of the recording medium, the 
heat-fusible binder will become molten or softened to be lowered in 
viscosity and the microcapsules within the heat-transferable ink layer 
ruptured by the pressure from the platen, whereby the heated portion of 
the heat-transferable ink layer will be transferred to the recording 
medium. Then, the transfer ink penetrates into the inner portions of the 
fibrous structure of the recording medium with the aid of the oil agent 
released by rupture of the microcapsules. As a result, it is rendered 
possible to prevent even a recording medium with poor surface smoothness 
from generations defects in the printed letter images, thus improving the 
quality of the printed letters. 
The heat-sensitive transfer material of the invention is based on the 
foregoing knowledge and, more specifically, comprises a support and a 
heat-transferable ink layer formed on the support, said heat-transferable 
ink layer comprising microcapsules enclosing therein a colorant and a 
liquid or semi-solid oil agent dispersed in a heat-fusible binder. 
The heat-sensitive transfer recording method of the present invention 
comprises providing the above described heat-sensitive transfer material, 
superposing said heat-sensitive transfer material on a recording medium 
with its heat-transferable layer facing the recording medium and heating 
the heat-transferable layer of the heat-sensitive transfer material in a 
desired pattern to leave the image of the heat-transferable ink 
corresponding to the heated pattern on the recording medium after 
separation of the recording medium and the heat-sensitive transfer 
material. 
According to a preferred embodiment of the present invention, magnetic 
powder and/or foaming agent are contained in the heat-transferable layer 
preferably with at least the magnetic powder being encapsulated together 
with the oil agent. 
The present invention is described in more detail below by referring to the 
drawings, as desired. The quantitative proportions expressed in "%" and 
"parts" in the following description are by weight, unless otherwise 
specifically noted.

DETAILED DESCRIPTION OF THE INVENTION 
FIG. 1 is a schematic sectional view in the thickness direction of the most 
basic embodiment of the heat-sensitive transfer material of the present 
invention. More specifically, the heat-sensitive transfer material 1 
generally comprises a heat-transferable ink layer 3 formed on the support 
2 in the form of a sheet (sheet being used to include films). 
As the support 2, it is possible to use films or papers known in the art as 
such. For example, films of plastics having relatively good heat 
resistance such as polyester, polycarbonate, triacetylcellulose, nylon, 
polyimide, etc., Cellophane or parchment paper can preferably be used. The 
support should have a thickness desirably of about 2 to 15 microns when 
considering a thermal head as the heating source during heat transfer, but 
it is not particularly limited when using a heating source capable of 
selectively heating the heat-transferable ink layer, such as a laser beam. 
Also, in the case of using a thermal head, the surface of the support 
contacting the thermal head can be provided with a heat-resistant 
protective layer comprising a silicone resin, a fluorine-containing resin, 
a polyimide resin, an epoxy resin, a phenol resin, a melamine resin or 
nitrocellulose to improve the heat resistance of the support. Further, a 
support material which could not be used heretofore can also be used. 
The heat-transferable ink layer 3 comprises microcapsules 5 enclosing a 
colorant and an oil agent dispersed in a heat-fusible binder 4. 
The heat-fusible binders may include waxes such as carnauba wax, paraffin 
wax, sazol wax, microcrystalline wax, castor wax and the like; higher 
fatty acids or derivatives thereof, for example, metal salts or esters 
thereof including stearic acid, palmitic acid, lauric acid, aluminum 
stearate, lead stearate, barium stearate, zinc stearate, zinc palmitate, 
methylhydroxystearate, glycerol monohydroxystearate and the like; 
thermoplastic resins comprising homopolymers or copolymers of olefins or 
their derivatives such as polyethylene, polypropylene, polyisobutylene, 
polyethylene wax, polyethylene oxide, polytetrafluoroethylene, 
ethylene-acrylic acid copolymer, ethyleneethyl acrylate copolymer, 
ethylene-vinyl acetate copolymer and the like. These heat-fusible binders 
may be used either singly or in a mixture of two or more kinds. 
The colorants may include all of various pigments and dyes employed in the 
field of printing and recording, for example, Carbon Black, Nigrosine 
dyes, Lamp Black, Sudan Black SM, Alkali Blue, Fast Yellow G, Benzidine 
Yellow, Pigment Yellow, Indofast Orange, Irgadine Red, Paranitroaniline 
Red, Toluidine Red, Cermine FB, Permanent Bordeaux FRR, Pigment Orange R, 
Resol Red 2G, Lake Red C, Rhodamine FB, Rhodamine B Lake, Methyl Violet B 
Lake, Phthalocyanine Blue, Pigment Blue, Brilliant Green B, Phthalocyanine 
Green, Oil Yellow GG, Zapon Fast Yellow CGG, Kayaset Y963, Kayaset TG, 
Sumiplast Yellow GG, Zaponfast Orange RR, Oil Scarlet, Sumiplast Orange G, 
Orazole Brown B, Zaponfast Scarlet CG, Aizenspiron Red BEH, Oil Pink OP, 
Victoria Blue F4R, Fastogen Blue 5007, Sudan Blue, Oil Peacock Blue, etc. 
Also, magnetic powder as described hereinafter is also useful as a 
colorant. 
The oil agent to be used in the present invention is liquid at room 
temperature or semi-solid having a softening point or a melting point of 
60.degree. C. or lower. Typical examples of such oil agents may include 
animal or vegetable oils such as cottonseed oil, rapeseed oil, camellia 
oil, castor oil, peanut oil, lanolin, tallow, lard, whale oil, etc., 
mineral oils such as motor oil, spindle oil, dynamo oil, etc., petrolatum, 
glycerine, polyethylene glycol, dioctyl phthalate, monoolein, sorbitane 
trioleate, etc. In addition, waxes, higher fatty acids or their 
derivatives such as metal salts, esters, etc., and thermoplastic resins 
are also available, provided that they satisfy the above conditions. 
For obtaining the microcapsules enclosing the colorant and the oil agent, 
it is possible to employ the conventionally used methods for 
microencapsulation, such as the method in which a mixture of the colorant 
and the oil agent is dispersed in a solution of a wall-forming resin and 
the dispersion is spray dried, or the phase separation method, the complex 
coacervation method, the interfacial polymerization method, etc. The 
wall-forming resins to be utilized may be any of the thermoplastic resins 
or thermosetting resins known in the art suitable for these 
microencapsulation methods. 
The microcapsules employed may have sizes of 0.1 to 30.mu., particularly 
preferably 0.1 to 10.mu.. The thickness of the resin walls should 
preferably be within the range of from 0.1 to 0.5.mu.. The proportions of 
the respective components in the microcapsules are preferably 2 to 200 
parts, particularly 5 to 100 parts of the oil agent, per 10 parts of the 
colorant. Ten parts of such microcapsules are blended with 2 to 200 parts, 
preferably 5 to 100 parts of a heat-fusible binder, optionally diluted 
with a solvent or a dispersing medium, to obtain a coating solution, which 
is in turn applied by a hot melt coater or a solvent coater on the support 
2, followed by drying to form the heat-transferable ink layer 3, thus 
providing the heat-sensitive transfer material 1 of the present invention. 
In the heat-fusible binder 4 or the microcapsule 5 constituting the 
heat-transferable ink layer 3 as described above, it is also possible to 
incorporate dispersants, fillers or additional colorants. 
According to a preferred embodiment of the present invention, magnetic 
powder and/or a foaming agent is incorporated, preferably with at least 
the magnetic powder being encapsulated together with the oil agent. 
The magnetic material may be any of those generally known as the 
ferromagnetic materials, including, for example, metals of ferromagnetic 
elements such as iron, cobalt, nickel, manganese, etc., or alloys 
containing these as the main components, or oxides of these elements such 
as magnetite, hematite, ferrite, etc., and other compounds including these 
ferromagnetic elements. The magnetic powder should preferably have an 
average particle size of 0.05.mu. or above but may broadly have 0.01 to 
10.mu., particularly preferably 0.05 to 5.mu.. 
Also, a magnetic fluid containing magnetic powder dispersed in an oil agent 
is commercially available. For example, a magnetic fluid is available from 
Matsumoto Yushi Seiyaku K.K. under the trade name of "Marpomagna FN-40". 
The foaming agents to be employed may be thermally decomposable foaming 
agents or readily volatile organic liquids. The thermally decomposable 
foaming agent may preferably be a substance which can be chemically 
decomposed under heating to generate gas and also satisfies the following 
conditions: 
(1) it can be stably dispersed or dissolved in the ink material (thus, in 
the present specification, the "dispersed" state of the heat decomposable 
foaming agent in the heat-fusible binder is also inclusive of the 
dissolved state); 
(2) it is stable at room temperature and can decompose at a temperature of 
200.degree. C. or lower; 
(3) the decomposed gas is not corrosive or toxic; 
(4) the decomposed gas is free from objectionable odor and contaminating 
properties; and 
(5) the agent itself and its decomposed residue do not react with the oil 
agent or heat-fusible binder to cause decoloration or denaturation. 
For example, inorganic foaming agents satisfying these conditions include 
bicarbonates such as sodium bicarbonate, ammonium bicarbonate, etc.; 
carbonates such as ammonium carbonate, magnesium carbonate, etc.; 
equimolar mixture of sodium nitrite and ammonium chloride; azide compounds 
such as CaN.sub.6 or BaN.sub.6 ; ferrous oxalate; ammonium persulfate; 
sodium borohydride; and so on. Examples of organic foaming agents are azo 
type foaming agents such as azodicarbonamide (ADCA), 
azobisisobutyronitrile (AIBN), diazoaminobenzene (DAB), etc.; nitroso type 
foaming agents such as N,N'-dinitrosopentaethylenetetramine (DPT or DNTD), 
N,N'-dimethyl-N,N'-(DMDNTA), etc.; sulfonyl hydrazide type foaming agents 
such as p-toluenesulfonyl hydrazide (TSH), benzenesulfonyl hydrazide 
(BSH), p,p'-oxybisbenzenesulfonyl hydrazide, etc. 
These inorganic foaming agents or organic foaming agents may be used either 
singly or as a mixture of two or more kinds in the same system or two or 
more kinds selected from both of the systems. If desired, a foaming aid 
may also be formulated in the foaming agent for the purpose of controlling 
the decomposition temperature of the foaming agent. 
The foaming aid may be any compound having a function of lowering the 
decomposition temperature of the foaming agent employed when combined with 
the foaming agent, and, depending on the foaming agent used, those 
enumerated below may be available. For example, there may be included 
oxalic acid, lactic acid, citric acid, succinic acid, malic acid, benzoic 
acid, salicylic acid, fumaric acid, malonic acid, adipic acid, gallic 
acid, toluenesulfonic acid, phosphoric acid, guanidine carbonate, 
ethanolamine, potassium carbonate, borax, boric acid, silicid acid, 
cadmium oxide, zinc oxide, zinc acetate, zinc chloride, zinc nitrate, zinc 
laurate, zinc powder, mercury acetate, mercury oxide, barium stearate, 
calcium stearate, magnesium oxide, calcium carbonate, lead carbonate, lead 
acetate, lead oxide, lead sulfate, dibasic phosphite, stannous oxide, 
Dexy-clay, dimethylformamide, aluminum stearate, titanium oxide, boron 
trifluoride, urea and so on. When there is a possibility of generation of 
a small amount of formaldehyde during heat decomposition as in the case of 
using an organic weak acid as the foaming aid, it is preferred to employ a 
compound having an action to capture formaldehyde such as urea in 
combination. 
As the readily volatile organic liquid, any of the compounds used in the 
field of resin processing as an evaporation type foaming agent or a 
readily volatile foaming agent can be used as such also in the present 
invention. The readily volatile organic liquid to be preferably used is 
generally liquid at around room temperature and normal pressure, and a 
compound having a boiling point of 130.degree. C. or lower, particularly 
100.degree. C. or lower. Typical examples of the readily volatile organic 
liquids are set forth below: 
(a) Aliphatic hydrocarbons: 
For example, hydrocarbons having 4 to 7 carbon atoms such as n-propane, 
n-pentane, n-hexane, neopentane, isohexane, n-heptane, isoheptane and the 
like. These are low in toxicity and economical. 
(b) Chlorinated aliphatic hydrocarbons: 
For example, methyl chloride, methylene dichloride, trichloroethylene, 
dichloroethane (sym), and the like. 
(c) Fluorinated aliphatic hydrocarbons: 
For example, chlorine-fluorine derivatives of methane or ethane such as 
Freon-11 (CCl.sub.3 F), Freon-12 (CCl.sub.2 F.sub.2), Freon-21 (CHCl.sub.2 
F), Freon-22 (CHClF.sub.2), Freon-113 (CCl.sub.2 F-CClF.sub.2), Freon-114 
(CClF.sub.2 -CClF.sub.2) are frequently used. 
(d) Aromatic hydrocarbons: 
Benzene, toluene and the like. 
The readily volatile organic liquid may be used by microencapsulating it 
together with the colorant and the oil agent or as separate microparticles 
containing it within resin microparticles by impregnation or 
microencapsulation. In the case of the resin impregnation method, it is 
possible to employ, for example, a method in which a readily volatile 
organic liquid is added during the process of suspension polymerization of 
an appropriate monomer (Japanese Patent Publication No. 3190/1958) or a 
method in which beads obtained by suspension polymerization are swelled 
with a solvent and a readily volatile organic liquid is added thereto 
(Japanese Patent Publication No. 10628/1961). If desired, the resin may be 
micropulverized before impregnation with a readily volatile organic 
liquid. The microencapsulation method is also inclusive of various methods 
such as the complex coacervation method, the interfacial polymerization 
method and the phase separation method known in the art. Various 
commercial products are available as microcapsules enclosing readily 
volatile organic liquid, such as Matsumoto Microsphere F30, F50 and F60 
produced by Matsumoto Yushi Seiyaku K.K. or Expancell produced by Nippon 
Philite K.K. (enclosing a foaming agent of isobutane within a wall 
material of vinylidene chloride/acrylonitrile copolymer). 
Including those as described above, as the microparticulate filler material 
containing a readily volatile organic liquid, it is preferred to use one 
having particle sizes of 0.1 to 30 microns, particularly 0.1 to 10 
microns, above all one with smaller particle sizes. 
When magnetic powder is employed, this should preferably be 
microencapsulated together with the oil agent to give a proportion of 2 to 
200 parts, particularly 5 to 100 parts, of the oil agent per 10 parts of 
the magnetic powder. 
The foaming agent can be microencapsulated together with the oil agent and 
the colorant. In this case, the amount of the foaming agent may preferably 
be within the range of 2 to 20 parts, particularly 2 to 10 parts, per 10 
parts of the colorant (including magnetic powder). If too much foaming 
agent is used, the ink becomes too viscous and poor in penetration into 
the recording medium, while too little foaming agent fails to produce an 
effect. 
Alternatively, the foaming agent may also be dispersed in the heat-fusible 
binder separately from the microcapsules enclosing the oil agent and the 
colorant. FIG. 2 shows a schematic sectional view in the thickness 
direction of a heat-sensitive transfer material 1a according to this 
embodiment. In this embodiment, the heat-transferable ink layer 3a 
comprises microcapsules 5a enclosing the oil agent and the colorant 
(including magnetic material) and a foaming agent 6 dispersed therein. The 
respective components 3a constituting the heat-transferable ink layer may 
be similar to those described in the embodiment shown in FIG. 1. When 
employing a readily volatile organic liquid as the foaming agent, this 
should preferably be incorporated in the resin by impregnation as 
described above or dispersed in the heat-fusible binder 4 as the 
microparticulate filler enclosed by microencapsulation. In this 
embodiment, it is preferred to formulate 2 to 200 parts, particularly 5 to 
100 parts of the oil agent per 10 parts of the colorant in the 
microcapsule 5a, and 2 to 30 parts, particularly 2 to 20 parts of the 
foaming agent, 2 to 100 parts, particularly 5 to 50 parts of the 
heat-fusible binder, per 10 parts of the microcapsule. 
Also, as an embodiment related to FIG. 2, the heat-transferable ink layer 
can be divided into the layer 3b containing the blowing agent 6 and the 
layer 3c containing the microcapsule 5a enclosing the colorant (including 
magnetic powder) and the oil agent, as shown in FIG. 3. The proportions of 
the respective components in this case are substantially the same as those 
in the case of FIG. 2. 
In any of the above cases of FIG. 1 to FIG. 3, additives such as 
dispersants, fillers, etc. may also be added in the heat-fusible binder 4 
or the microcapsule 5 or 5a constituting the heat-transferable ink layer, 
as desired. Also, for increasing the color density of the 
heat-transferable ink layer or controlling its tone, an additional 
colorant may be added into the heat-fusible binder 4. 
The heat-sensitive transfer material of the present invention generally has 
a planar shape which is not particularly limited, but it is generally 
shaped in a typewriter ribbon or a tape with a large width as used in line 
printers, etc. Also, for the purpose of color recording, it can be made a 
heat-sensitive transfer material in which heat-fusible ink is coated into 
several kinds of color tones in stripes or blocks. 
Next, the heat-sensitive transfer recording method employing the above 
heat-sensitive transfer material is described by referring to the case in 
which a thermal head is employed as the most typical heat source. FIG. 4 
is a schematic sectional view in the thickness direction of the 
heat-sensitive transfer material showing its outline. More specifically, 
the heat-fusible ink 3 of the heat-sensitive transfer material 1 is caused 
to closely contact the recording medium, and while being given a heat 
pulse by means of the thermal head 8 with an additional heat pulse, if 
desired, from the platen 7, the ink layer 3 is heated locally in 
correspondence to the desired printed letter or the transfer pattern. The 
portion to be heated of the ink layer 3 will be softened or melted on 
reaching a certain temperature and will abruptly become lower in 
viscosity. As the result, the microcapsules are ruptured by the pressure 
from the platen, and the penetrating ink enclosed therein is transferred 
together with the softened or melted binder onto the recording medium 6. 
After transfer, the penetrating ink released from the capsules can 
penetrate through the penetrating force of the oil agent even into the 
inner portions of the fibrous structure of the recording medium where no 
heat transfer ink of the prior art could penetrate, thus giving a recorded 
image 33 of good printed letter quality, having the penetrated and filled 
portion 33a without defect of the printed letter image, even on the 
recording medium of poor surface smoothness. 
In this case, when a foaming agent is contained in the heat-transferable 
ink layer either in the form of being microencapsulated (FIG. 1) or being 
directly dispersed in the heat-fusible binder of the ink layer 3a or 3b 
(FIG. 2 or FIG. 3), the gas pressure generated by decomposition or 
gasification of the blowing agent dispersed just before or after softening 
or melting of the ink layer 3 (or 3a or 3b) at the heated portion will 
promote breakage of the microcapsules and also adhesion of the ink onto 
the surface concavities of the recording medium 7. By such mechanism, the 
penetration of the attached ink into the inner portions of the fibrous 
structure of the recording medium through the penetrating force of the oil 
agent can be enhanced effectively. 
On the other hand, when magnetic powder is contained in the 
heat-transferable ink layer 3 by microencapsulation together with the oil 
agent, by use of, for example, a platen 8 having a built-in permanent 
magnet, magnetic attracting force is permitted to act on the magnetic ink 
released from the microcapsules from the heat-sensitive transfer material 
to the recording medium 7, whereby attachment of the ink onto the surface 
concavities of the recording medium 7 can be promoted. Thus, similarly, 
the penetration of the attached ink into the inner portions of the fibrous 
structure of the recording medium through the penetrating force of the oil 
agent can be enhanced effectively. 
For applying magnetic attractng force on the heat-sensitive transfer 
material 1, toward the recording medium 7, any desired magnetic field 
generating means other than a permanent magnet may be used. The strength 
of the magnetic field is not particularly limited, but it is generally 400 
Oersted or higher. 
As described in detail above, according to the present invention, there is 
provided a heat-sensitive transfer material in which colorant and oil 
agent are dispersed after microencapsulation thereof in a 
heat-transferable ink layer, and, by using the transfer material, it has 
been rendered possible to effect recording with a good quality of printed 
letters even on a recording medium with poor surface smoothness while 
maintaining various good heat transfer performances, including storability 
of the heat transfer material. Also, when a foaming agent and/or magneitc 
powder are used in combination, adhesiveness of the magnetic ink to the 
recording medium can be improved to further promote penetration of the 
ink. 
The present invention is described below by referring to the following 
Examples and Comparative examples. 
EXAMPLE 1 
Ten parts of carbon black, 25 parts of castor oil and 5 parts of lecithin 
were kneaded by means of a three-roll mill to obtain a penetrating ink. 
One hundred grams of this ink were emulsified in 400 g of an aqueous 2% 
gelatin solution by means of a homomixer at 8000 rpm to obtain an emulsion 
with particle sizes of 1 to 2 .mu.m. This dispersion was adjusted to pH 
8-9 with an aqueous 10% sodium carbonate solution and 50 g of a 
urea-formalin prepolymer was added under the condition of a liquid 
temperature of 25.degree. C. under stirring, followed by adjustment of pH 
to 4 with acetic acid. Subsequently, the above emulsion was heated under 
stirring and maintained at 30.degree. C. for 3 hours and at 50.degree. C. 
for 2 hours to obtain a microcapsule dispersion having urea-formalin resin 
walls enclosing penetrating ink particles. The dispersion was cooled and 
filtered to obtain microcapsules of 1 to 2 .mu.m enclosing penetrating ink 
therein. 
One part of polyethylene wax (softening point: about 95.degree. C.), 2 
parts of paraffin wax (softening point: about 70.degree. C.) and one part 
of carnauba wax were mixed by heating at 100.degree. C. under stirring. 
Then, 16 parts of a petroleum solvent (trade name: Isopar H, produced by 
Esso) were added to the mixture, and the mixture was heated at about 
100.degree. C. and thereafter cooled under vigorous stirring to room 
temperature to obtain a fine dispersion of wax. 
A coating solution obtained by mixing under stirring 20 parts of the above 
fine dispersion of wax with 4 parts of the microcapsules was applied on a 
polyester film with a thickness of 6 .mu.m and dried to obtain a 
heat-sensitive transfer material having a transfer layer with a thickness 
of 10 .mu.m. 
EXAMPLE 2 
______________________________________ 
Carbon Black 10 parts 
Hexane 5 parts 
Rapeseed oil 20 parts 
Methyl methacrylate 90 parts 
Acrylonitrile 10 parts 
Divinylbenzene 0.025 part 
Hydrophobic amine 0.5 part 
(Duomine-T, produced by Lion-Armor K.K.) 
Benzoyl peroxide 0.2 part 
______________________________________ 
The above components were mixed and dispersed homogeneously to obtain an 
oily mixture. 
______________________________________ 
Deionized water 100 parts 
Hydrophilic silica 3 parts 
(A-300, produced by Nippon Aerosil K.K.) 
Potassium bichromate 
0.025 part 
______________________________________ 
An aqueous solution having the above composition was adjusted to pH 4 and 
the above oily mixture was emulsified into this aqueous solution by means 
of a homo-mixer at 12,000 rpm, and thereafter the reactor was immediately 
sealed and the reaction was carried out at 80.degree. C. for 24 hours. 
After completion of the reaction, the reaction product was filtered and 
the solids were dried at 30.degree. C. to obtain microcapsules of 1-2.mu. 
in which the oily material was encapsulated with a ternary copolymer of 
methyl methacrylate, acrylonitrile and divinylbenzene. 
A coating solution obtained by mixing under stirring 20 parts of the fine 
dispersion of wax employed in Example 1 and 4 parts of the above 
microcapsules was applied on a polyester film with a thickness of 6.mu. 
and dried to obtain a heat-sensitive transfer material having a 
heat-transferable ink layer with a thickness of 10 .mu.m. 
EXAMPLE 3 
A mixture of 15 parts of ferrite, 25 parts of castor oil and 5 parts of 
lecithin was kneaded on a three-roll mill to obtain a penetrating ink. 
This mixture and 0.4 g of terephthalic chloride were added into 400 ml of 
an aqueous 0.5% sodium bicarbonate solution and emulsified by means of a 
homo-mixer to oil droplet sizes of 1 to 2.mu.. Further, while stirring was 
continued, 100 ml of an aqueous 10% ethylene glycol solution was added and 
stirring was continued for 10 minutes. Then, the dispersion was spray 
dried by means of a spray dryer to obtain powdery microcapsules enclosing 
the penetrating ink within polyester walls. 
To 20 parts of the fine dispersion of wax obtained in Example 1 were added 
4 parts of the above microcapsules and 2 parts of microcapsules enclosing 
readily volatile organic liquid (Microsphere F produced by Matsumoto Yushi 
K.K.), followed by mixing under stirring, to obtain a coating solution. 
The coating solution was applied on a polyester film with a thickness of 
6.mu. similarly as in Example 1 to obtain a heat-sensitive transfer 
material having a heat-transferable ink layer with a thickness of 10.mu.. 
EXAMPLE 4 
A mixture of 10 parts of carbon black, 25 parts of cottonseed oil, 5 parts 
of lecithin and 4 parts of ammonium carbonate was kneaded on a three-roll 
mill to obtain a penetrating ink. By use of this penetrating ink in place 
of the penetrating ink of Example 3, microcapsules were obtained according 
to the procedure of Example 3. 
To 20 parts of the fine dispersion of wax obtained in Example 1 were added 
4 parts of the above microcapsules, followed by mixing under stirring, to 
obtain a coating solution. This coating solution was applied on a 
polyester film with a thickness of 6.mu. similarly as in Example 1 to 
obtain a heat-sensitive transfer material having a heat-transferable ink 
layer with a thickness of 10.mu.. 
EXAMPLE 5 
Example 4 was repeated except for changing ammonium carbonate to calcium 
azide to obtain a heat-sensitive transfer material. 
EXAMPLE 6 
By use of a penetrating ink comprising 10 parts of carbon black, 25 parts 
of lanolin, 5 parts of lecithin, 4 parts of azodicarbonamide and 0.2 part 
of ethanolamine, a heat-sensitive transfer material was obtained similarly 
as in Example 4. 
EXAMPLE 7 
A mixture of 15 parts of ferrite, 25 parts of repeseed oil and 5 parts of 
lecithin was kneaded on a three-roll mill to obtain a penetrating ink. By 
using this penetrating oil in place of the penetrating ink of Example 1, 
microcapsules were obtained following the procedure of Example 1. 
Then, by use of the microcapsules, a heat-sensitive transfer material was 
obtained similarly as in Example 1. 
EXAMPLE 8 
Example 2 was repeated except for using 10 parts of ferrite in place of 10 
parts of carbon black to obtain a heat-sensitive transfer material. 
EXAMPLE 9 
Fifteen parts of ferrite, 25 parts of rapeseed oil and 5 parts of lecithin 
were kneaded by means of a three-roll mill to obtain a penetrating ink. 
One hundred grams of this ink were emulsified in 400 g of an aqueous 2% 
gelatin solution by means of a homomixer at 800 rpm to obtain an emulsion 
with particle sizes of 1 to 2 .mu.m. This dispersion was adjusted to pH 
8-9 with an aqueous 10% sodium carbonate solution and 50 g of a 
urea-formalin prepolymer was added under the condition of a liquid 
temperature of 25.degree. C. under stirring, followed by adjustment of pH 
to 4 with acetic acid. Subsequently, the above emulsion was heated under 
stirring and maintained at 30.degree. C. for 3 hours and at 50.degree. C. 
for 2 hours to obtain a microcapsule dispersion having urea-formalin resin 
walls penetratable ink particles. The dispersion was cooled and filtered 
to obtain microcapsules of 1 to 2.mu. enclosing the penetrating ink 
therein. 
To 20 parts of the fine dispersion of wax obtained in Example 1 were added 
4 parts of the above microcapsules and 2 parts of microcapsules enclosing 
readily volatile organic liquid (Microsphere F produced by Matsumoto Yushi 
K.K.), followed by mixing under stirring, to obtain a coating solution. 
The coating solution was applied on a polyester film with a thickness of 
6.mu. similarly as in Example 1 to obtain a heat-sensitive transfer 
material having a heat-transferable ink layer with a thickness of 10.mu.. 
EXAMPLE 10 
A mixture of 10 parts of ferrite, 25 parts of rapeseed oil, 5 parts of 
lecithin and 4 parts of ammonium carbonate was kneaded on a three-roll 
mill to obtain a penetrating ink. By use of this penetrating ink in place 
of the penetrating ink of Example 9, microcapsules were obtained according 
to the procedure of Example 9. 
To 20 parts of the fine dispersion of wax obtained in Example 1 were added 
4 parts of the above microcapsules, followed by mixing under stirring, to 
obtain a coating solution. This coating solution was applied on a 
polyester film with a thickness of 6.mu. similarly as in Example 1 to 
obtain a heat-sensitive transfer material having a heat-transferable ink 
layer with a thickness of 10.mu.. 
EXAMPLE 11 
Example 10 was repeated except for changing ammonium carbonate to calcium 
azide to obtain a heat-sensitive transfer material. 
EXAMPLE 12 
By use of a penetratable ink comprising 10 parts of ferrite, 25 parts of 
lanolin, 5 parts of lecithin, 4 parts of azodicarbonamide and 0.2 part of 
ethanolamine, a heat-sensitive transfer material was obtained similarly as 
in Example 10. 
EXAMPLE 13 
A mixture of 20 parts of a magnetic fluid (trade name: Marpomagna FN-40, 
produced by Matsumoto Yushi Seiyaku), 4 parts of calcium azide and 0.2 
part of terephthaloyl chloride was mixed and stirred by means of a 
homo-mixer. The resultant mixture was emulsified into 200 ml of an aqueous 
0.5% sodium bicarbonate solution to oil droplet sizes of 1-2.mu.. While 
stirring was continued, 50 ml of 10% ethylene glycol was added to the 
emulsion and stirring was further continued for 10 minutes. Then, the 
mixture was spray dried by a spray dryer to obtain microcapsule powder 
having polyester walls with thicknesses of 1 to 2.mu.. 
The microcapsules of Example 10 were replaced with the above microcapsules, 
following otherwise the same procedure as in Example 10, to obtain a 
heat-sensitive transfer material. 
COMATIVE EXAMPLE 1 
A typical example of the heat-sensitive transfer material of the prior art 
was prepared as follows. That is, one part of carbon black, one part of 
polyethylene wax (softening point: about 95.degree. C.), 2 parts of 
paraffin wax (softening point: about 70.degree. C.) and one part of 
carnauba wax were mixed and dispersed by means of an attritor by heating 
at about 100.degree. C. Then, 30 parts of a petroleum solvent (trade name: 
Isopar, produced by Esso) were added to the mixture, and heated to about 
100.degree. C., followed by cooling to room temperature under vigorous 
stirring, to obtain an Isopar H solution containing carbon black/wax 
finely dispersed therein. 
The above dispersion was applied on a polyester film with a thickness of 6 
.mu.m and dried to obtain a heat-sensitive transfer material with a 
transfer ink layer of 10 .mu.m. 
By use of the various kinds of heat-sensitive transfer materials, recording 
was effected on three kinds of recording paper (bond paper with Bekk 
smoothness of 15 sec., wood free papers with Bekk smoothness of 30 sec. 
and 100 sec.) according to a heat-sensitive transfer-type facsimile 
machine which operates according to the mechanism as substantially 
described with regard to FIG. 4, and their resolutions were evaluated. For 
Examples 7-13, recording was performed while permitting a magnetic field 
of 1200 Oersted to act on the laminated portion of the recording paper by 
the permanent magnet built in the platen 8. 
In the comparison example, the best value of resolution obtained by use of 
an electrophotographic chart as the original was 6.3 lines/mm for the wood 
free paper with Bekk smoothness of 100 sec., which value being decreased 
as 4.5 lines/mm for the high quality paper of 30 sec. and 3.6 lines/mm for 
the bonded paper of 15 sec. In contrast, by use of the heat-sensitive 
transfer materials of the present invention of Examples 1 through 13, a 
resolution of 6.3 lines/mm could be obtained for wood free paper of 30 
sec. and 5.6 lines/mm even for bonded paper of 15 sec. 
As apparently seen from the above results, when using the heat-sensitive 
transfer material of the present invention, lowering in resolution is very 
little even when the smoothness of the paper may be lowered. The recorded 
image by the heat-sensitive transfer material obtained in Examples 6 and 
12 had a very good sharpness of recording. This may be attributable to 
closeness of the melting temperature of the heat-fusible ink to the 
decomposition temperature of the foaming agent, whereby the molten ink 
could be very effectively transferred.