JPH0363181A - Thermal transfer recording method and thermal transfer material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a thermal transfer material used for thermal transfer recording, specifically,
The present invention relates to a thermal transfer material and a thermal transfer recording method that allow good recording to be obtained even if the amount of thermal transfer material used is reduced.

[Conventional technology]

In addition to the general features of thermal recording methods, such as the equipment used is lightweight, compact, noiseless, and has excellent operability and maintainability, the thermal transfer recording method does not require colored processed paper, and it also improves the quality of the recorded image. It has the feature of excellent durability and has been widely used recently.

This thermal transfer recording method uses a thermal transfer material in which a thermal transferable ink layer consisting of a colorant dispersed in a heat-melting binder is coated on a support, which is generally in the form of a sheet. By overlapping the thermally transferable ink layer so that it is in contact with the recording medium, and applying heat from the base material side using a thermal head to transfer the melted ink layer to the recording medium,
A transferred recorded image is formed on a recording medium according to a heat supply shape (pattern).

In conventional thermal transfer recording, the thermal transfer ink is almost completely transferred from the thermal transfer material to the recording medium with a single application of heat, so it is disposable, has high running costs, and can be kept confidential from the used thermal transfer material. There was also concern that the information would be leaked.

On the other hand, JP-A-57-83471 and JP-A-582
As in No. 01686 or Japanese Patent Publication No. 62-58917, there is a recording method (hereinafter referred to as double-density recording) that reduces the amount of thermal transfer material used by providing a relative speed between the thermal transfer material and the recording medium. Proposed.

[Problem that the invention is trying to solve]

However, this recording method has some problems like the conventional method.

The first problem is that so-called sticking occurs because the thermally transferable ink layer transferred to the recording medium does not cohesively fail within the ink layer.

As a result, the conveyance of the thermal transfer material or the conveyance of the recording medium becomes irregular, and the ink transferred to the recording medium becomes uneven, resulting in a decrease in the sharpness, density, and uniformity of the density of the recorded image.

Furthermore, in the worst case, the thermal transfer material may break.

The second problem is that background smudge (unnecessary ink transfer to a recording medium such as paper) occurs.

This occurs because in double-density recording, the thermal transfer material and the recording medium slide, so the ink layer of the thermal transfer material is scratched off the surface of the recording medium and transferred to the entire surface of the recording medium.

As a countermeasure against scumming, Japanese Patent Application Laid-Open No. 178088/1988 proposes a heat-sensitive transfer material in which an overlayer containing no colorant is provided on an ink layer.

The third problem is that unnecessary whisker-like transfer, so-called trailing, occurs at the end of the transferred ink layer in the head running direction.

This is presumed to be due to excessive ink cohesive failure in the ink layer other than the ink layer subjected to heat application.

As a countermeasure against whisker-like transfer, there is a description in Japanese Patent Application No. 1-25278 previously filed by the present applicant.

In the above-mentioned publication, a thermal transfer ink made by dispersing a coloring material in a heat-melting binder made of ethylene vinyl acetate copolymer and wax is used, and by setting its breaking strength within a specific range, it can be used not only for whisker-like transfer. The first problem, scumming, is also prevented and solved.

The fourth problem is that in manufacturing a thermal transfer material, it is difficult to homogenize the thermal transfer ink layer.

Generally, the so-called hot-melt method and the solvent coating method, in which the ink is dissolved or dispersed in an organic solvent or water, coated, and dried, are used to form a thermally transferable ink layer coated on a support. .

The thermal transfer material used for this double-density recording has a higher resin content than conventional thermal transfer materials because the breaking strength of the thermal transfer ink layer is set within a specific range. The melt viscosity is too high, making it difficult to apply. Furthermore, even in the latter solvent coating method, when the heat-melting binder is dispersed in an organic solvent or water, the breaking strength must be delicately controlled under drying conditions, resulting in extremely low production efficiency.

From the above, it is most suitable to employ a solvent coating method using a coating ink in which a heat-melting binder is dissolved in an organic solvent.

However, the waxes contained in the heat-melting binder have poor solubility in organic solvents, and the coating ink must be heated to a relatively high temperature, which poses a problem in workability. In addition, when heating is not performed, waxes precipitate, making it difficult to form a homogeneous thermal transfer ink layer having a predetermined breaking strength.

The present invention has been made to solve the above problems,
Provided is a thermal transfer recording method capable of obtaining a recorded image with little stickiness and uniform density, and further prevents scumming and whisker-like transfer so-called trailing, and also makes it possible to form the recorded image. The purpose of this invention is to provide a thermal transfer material that can

[Means to solve the problem]

The heat-sensitive transfer recording method of the present invention provides a heat-sensitive transfer material having a heat-transferable ink layer containing a heat-fusible binder on a support, wherein the heat-fusible binder contains at least a wax component and a resin component; Using a thermal transfer material in which the melting point m1)t of the wax component and the melting point mp2 of the resin component satisfy the following relationship: l mp 2 - mp 1 l210°C, the recording medium is moved relative to the recording head within the same time. The present invention is characterized in that the distance that the heat-sensitive transfer material moves relative to the recording head is shorter than the distance.

Further, the heat-sensitive transfer material of the present invention is a heat-sensitive transfer material having a heat-transferable ink layer containing a heat-melt binder on a support, wherein the heat-melt binder is at least an incyanate polymer of higher fatty acid pentaerythritol ester and consists of a wax component containing a higher fatty acid polyhydric alcohol ester and a resin component, and the melting point mpl of the wax component and the melting point mp2 of the resin component
is characterized in that it satisfies the relationship: mp2-mp11≦10°C.

The present invention will be described below with reference to the drawings.

In addition, in the following description, "%" and "%" representing quantitative ratios are used.
Parts are by weight unless otherwise specified.

The thermal transfer recording method (double-density recording method) using the thermal transfer material of the present invention is, as shown in FIG. By heating with a recording head 3 such as a head, the thermal transferable ink of the thermal transfer material 1 is transferred to the recording medium 2 to obtain a recorded image. The thermal transfer material 1 and the recording medium 2 are continuously moved in the directions of arrows A and H by the rotation of the capstan roller 12, the pinch roller 13, and the platen roller 11, respectively, and are transferred onto the recording medium 2 one after another. A recording is made. The capstan roller 12 and the pinch roller 13 are driven by a motor 14, and the platen roller 12 is driven by a motor |≦. The transported thermal transfer material l is
The film is wound up by a winding roller 10 driven by a motor 14. A spring 16 presses the recording head 3 against the platen roller 11 via the thermal transfer material 1 and the recording medium 2.

In FIG. 1, the thermal transfer material 1 and the recording medium 2 are moving in the same direction, but as shown in FIG. The material 1 and the recording medium 2 may be moved in completely opposite directions.

Now, in this thermal transfer recording method, there may be a relative speed between the thermal transfer material 1 and the recording medium 2. In the example shown in FIG. 11, the head 3 does not move, and the thermal transfer material 1 moves slower than the recording medium 2.

In other words, when comparing the distance traveled by the thermal transfer material 1 and the distance traveled by the recording medium within the same time period, the distance traveled by the thermal transfer material 1 is shorter. As a result, with this recording method, the third
Recording is performed as shown in FIGS.

As shown in FIG. 3, when the width of the heating element 3a of the recording head 3 in the thermal transfer material feeding direction (arrow A direction) is l, 1
The second heat application is applied to a completely unused thermal transfer material l with a magnitude of l (FIG. 3). In addition, the thermal transfer material l is a support l.
A thermally transferable ink layer 1b is provided on a.

However, when heat is applied for the second time, the recording medium 2 moves l in the direction of arrow B, while the thermal transfer material 1 moves by 1/n (N=5° in FIG. 3) with respect to the recording head 3. The value of N depends on how many times the same part of the thermal transfer material 1 can be printed.
The part shown in FIG. 4 is the part that has already been subjected to heat application once and will be used again (FIG. 4).

When heat is applied continuously in the horizontal direction in this way, the heat-sensitive transfer material that receives heat from the second time onwards will be in an unused state by 1N, and the rest will have already been heat-applied several times by 1N. (Figures 4 to 6). In other words, the thermal transfer material is in the same state as if the same location had been used N times, and moreover, it is moving while rubbing the surface of the recording medium.

In the above example, it is assumed that the thermal transfer material l moves by 1N with respect to the recording head 3 during the second, third, etc. heat application, but the movement is less than 1 and more than It/N. If so, the thermal transfer material 1 can be saved. The above N is 2~
10. Furthermore, 3 to 8 are preferable.

In the above explanation, an example was shown in which the recording head 3 does not move. However, even when the thermal head 3 moves, the moving distance of each of the thermal transfer material l and the recording medium 2 is determined by the recording head 3.
If the distance from the recording head 3 is taken as a reference, it can be considered in the same way as the example explained in FIGS. 3 to 6. In other words, in the thermal transfer recording method of the present invention, the distance that the recording medium 2 moves relative to the recording head 3 within the same time is
The distance that the thermal transfer material 1 moves relative to the recording head 3 is shorter.

Now, as is clear from the above description, the thermal transfer material 1 of the present invention is heated by a heating element while sliding on a recording medium such as paper, and forms a recorded image on the recording medium 2. For this reason, the above-mentioned sticking is likely to occur, making it difficult to obtain a recorded image that is clearer, has good transferability, and has a uniform density.<<If the thermal transfer material curls, various problems are likely to occur.

Now, the present inventors have calculated the melting point rnp+ of the wax component in the heat-melting binder and the melting point mp21 mp of the resin component.
2 -m+) 1 It has been found that sticking can be reduced by setting the temperature to 1210°C.

Furthermore, by using an isocyanate polymer of higher fatty acid pentaerythritol ester or a mixture of the isocyanate polymer and higher fatty acid polyhydric alcohol ester as the wax component in the heat-melting binder, a homogeneous heat transferable ink with good workability can be obtained. It becomes possible to form a layer, and further, by setting the content of the wax component to 20 to 75% by weight based on the heat-melting binder, it is possible to obtain a heat-sensitive transfer material that prevents background stains and whisker-like transfer. becomes.

The thermal transfer material of the present invention will be explained in detail below.

First, the heat-melting binder will be explained.

The heat-melting binder forming the heat-transferable ink layer of the present invention contains at least a wax component and a resin component.

As wax components, conventionally known waxes such as natural waxes include vegetable waxes such as carnauba wax, candelilla wax, rice wax, and Japanese wax, mineral waxes such as ceresin wax and montan wax, and derivatives thereof. Examples of derivatives of montan wax include acid wax, ester wax, and partially saponified ester wax. Beeswax,
Animal waxes such as spermaceti wax and lanolin and their derivatives, and petroleum waxes such as paraffin wax and microcrystalline wax. As synthetic waxes, polyethylene wax, Fischer-Tropsch wax, etc. can be used.

Other higher fatty acids such as lauric acid, myristic acid, balmitic acid, stearic acid, behenic acid, higher alcohols such as stearyl alcohol and behenyl alcohol,
It is also possible to use esters such as sucrose fatty acid ester and sorbitan fatty acid ester, and amides such as oleylamide.

In particular, the heat-melting binder contains as a wax component an incyanate polymer of higher fatty acid pentaerythritol ester and, if necessary, higher fatty acid polyhydric alcohol ester.
It is most preferable to contain up to 75% by weight.

The isocyanate polymer of higher fatty acid pentaerythritol ester will be described in detail below.

It is obtained by reacting the higher fatty acid pentaerythritol ester with an isocyanate polymer.

%ζ12N The higher fatty acids constituting the ester include capric acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, and lignocerin. acids, saturated fatty acids such as cerotic acid, heptacanoic acid, montanic acid, melisic acid, lafcelic acid,
Acrylic acid, crotonic acid, incrotonic acid, caproleic acid, undecylic acid, oleic acid, elaidic acid, cetoleic acid, erucic acid, brassic acid, sorbic acid, linoleic acid, linuric acid, aragidonic acid, sardine acid, nisic acid, propiol acids, unsaturated fatty acids such as stearolic acid, branched fatty acids such as isovaleric acid, cycloaliphatic fatty acids such as malvalic acid, stearic acid, hydronocarbic acid, Schormoubleic acid, golulic acid, sabinic acid, ibrolic acid, and serapinol. Oxygen-containing fatty acids such as uniperinic acid, ricinoleic acid, feronic acid, and cerebronic acid can be used, and fatty acids having a melting point of 20° C. or higher and a carbon number of 10 to 30 can be particularly preferably used.

Pentaerythritol is used as the alcohol.

The above-mentioned higher fatty acids can be used alone or in combination of two or more.

The ester must be reactive with the isocyanate compound. That is, it must have a carboxyl group derived from a fatty acid or a hydroxyl group derived from pentaerythritol as an active hydrogen.

If the fatty acid used does not have a carboxyl group,
The ester is converted into a monoester, diester, or triester and subjected to reaction with an incyanate compound. Monoesters, diesters, and triesters can be used alone or as a mixture of two or three types.

Examples of the isocyanate compound include methyl isocyanate, ethyl incyanate, n-propylisocyanate, n-butyl isocyanate, octadecyl isocyanate, polymethyleneborifhenyl isocyanate, etc.
．． 4-tolylene diisocyanate), 4.4'-diphenylmethane diisocyanate, dianisidine diisocyanate, metaxylylene diisocyanate, 1.5-naphthalene diisocyanate, transvinylene diisocyanate, N,N'(4,4'-dimethyl-3, 32
-diphenyl diisocyanate) uredione, 2.6-
Diisocyanate methylcabroate etc., triphenylmethane triisocyanate, tris(4-phenylisocyanate thiophosphate) 4.4', 4'-
Trimethyl-3,3', 3'-t-diisocyanate-2,4,6-drifhenylcyamelate, etc. are used. Diisocyanates and triisocyanates are particularly preferred, and aromatic ones are more preferred.

The reaction between the ester and the isocyanate can be carried out using a heating and stirring operation according to a conventional method. If the heating temperature is too high, the coloring of the obtained product will be significant, and if it is too low, the reaction time will become long.
It is desirable to select a range of 0 to |≦0°C. The above reaction can also be carried out using metal salt catalysts such as stannic chloride, ferric chloride,
The use of potassium oleate, dibutyltin dilaurate, etc. allows the process to proceed relatively quickly at lower temperatures. It is appropriate that the reaction time is usually about 0.5 to 5 hours.

The amount of isocyanate used in the above reaction is appropriately selected depending on the type of each raw material used, reaction conditions, etc., but is usually about 0.1 to 40% by weight, preferably about 0.1 to 30% by weight based on the ester. The desired polymerization reaction can proceed within this range, and the wax can be produced.

The wax obtained as described above shows good solubility in organic solvents, especially toluene, xylene, benzene, etc., and it is possible to improve workability during the production of thermal transfer materials, that is, to reduce volatile solvents by heating the coating ink. Further, since there is no precipitation of waxes, a homogeneous thermal transferable ink layer can be formed extremely efficiently.

Furthermore, when the waxes are used, a homogeneous ink layer is formed, so that stickiness is further reduced and a recorded image with uniform density can be obtained.

In the heat-melting binder of the present invention, in addition to the above-mentioned isocyanate polymer of higher fatty acid pentaerythritol ester, it is effective to simultaneously use higher fatty acid polyhydric alcohol ester if necessary.

The polyhydric alcohol of the higher fatty acid polyhydric alcohol ester includes ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol,
dipropylene glycol, polypropylene glycol,
trimethylene glycol, butanediol, bentanediol, hexylene diol, octylene glycol,
Glycerin trimethylolpropane, pentaerythritol, dipentaerythritol, 1,3-butylene glycol, glycerin monoallyl, (4-(hydroxyethoxy)phenol)propane, nlubitol, sorbitol, neopentyl glycol, trishydroxyethyl isocyanurate, bisphenol, Hydrogenated bisphenol, bisphenol glycol ether, various epoxies (eg, triglycidyl isocyanurate), and the like are used.

The higher fatty acid pentaerythritol ester used in combination with the above-mentioned isocyanate polymer is effective in finely adjusting the melting point or melt viscosity of the entire wax component, thereby making it possible to vary the properties of the thermal transfer ink. .

The mixing amount of the ester is preferably 50% or less, more preferably 40% or less, and even more preferably 35% or less based on the total amount of the heat-melting binder.

If it exceeds 50%, the solubility of the wax component in the solvent will be poor, and workability will be lowered and curling will likely occur.

The amount of the isocyanate polymer or the mixture of the isocyanate polymer and higher fatty acid polyhydric alcohol ester (collectively referred to as the wax main component) is 20 to 75% by weight, preferably 30 to 6% by weight based on the total binder amount.
Contains 5% by weight.

If it is less than 20% by weight, the tensile strength of the thermal transferable ink layer becomes too large, and the viscosity when melted increases, resulting in an increase in the applied thermal energy, which tends to damage the thermal head, which is the heat source. Alternatively, if the supplied thermal energy is insufficient, the thermal transfer material and the recording medium will stick together, resulting in unstable running properties, resulting in blurred recorded images, insufficient density, and insufficient uniformity of density. If it exceeds 75% by weight, whisker-like transfer (tailing) and scumming occur, which is undesirable.

Further, the melting point of the wax main component is preferably in the range of 50°C to 90°C, more preferably in the range of 60°C to 85°C. If the temperature is lower than 50°C, the storage stability of the thermal transfer material will be poor and blocking will easily occur, and if it exceeds 90°C, the transferability will be poor, which is disadvantageous.

Furthermore, the melt viscosity of the wax main component is lO at 100°C.
~10 scpS1 preferably 10-500 cps
, more preferably 10 to 200 cps.

This is because when heated, the main wax component acts like a solvent for the resin component, so the viscosity of the thermal transfer ink decreases, which lowers the tensile strength and cohesive force of the ink layer, making the ink layer as a whole more likely to break. It is inferred that cohesive failure becomes easier, and sticking is further reduced. As a result, it is presumed that the sharpness of the recorded image increases and density deficiency or density uniformity is achieved.

Further, it is preferable that the difference between the melting end temperature and the melting start temperature of the wax main component is 5 to 20°C, more preferably 5 to 20°C.
～｜≦℃ is good.

That is, due to the sharp melting behavior, the viscosity of the thermal transfer ink described above decreases more steeply, making it possible to improve not only adhesion but also transferability.

The heat-sensitive transfer material of the present invention contains a resin component in addition to the wax main component as a heat-melting binder. Examples of resin components include polyolefin resins, polyamide resins, polyester resins, epoxy resins, polyurethane resins, polyacrylic resins, polyvinyl chloride resins, cellulose resins, polyvinyl alcohol resins, petroleum resins, Possible materials include phenolic resins, polystyrene resins, vinyl acetate resins, natural rubber, elastomers such as styrene-butadiene rubber, isoprene rubber, and chloroprene rubber, polyisobutylene, and polybutene.
In particular, ethylene-vinyl acetate copolymer or ethylene-ethyl acrylate copolymer is preferred as it has film properties and softens/melts well upon application of heat.
The content of the resin component is 25 to 80% of the total binder amount.
% by weight, more preferably 35 to 70% by weight, and 25% by weight.
If it is less than 80% by weight, it tends to cause whisker-like transfer, so-called trailing and scumming, and if it exceeds 80% by weight, it is undesirable because it causes deterioration in transferability, occurrence of sticking, increase in energy, and poor cutting performance.

In addition, the melt flow rate is |≦0~800g/1
0m1n, even more |≦0~400g 710
min is preferred. If the melt flow rate is smaller than |≦0 g/10 m1n, the melt viscosity becomes large and cohesive failure becomes difficult, resulting in a decrease in transferability or an increase in applied heating energy, and 800 g/1
If it is larger than 0 min, trailing and scumming are likely to occur.It is naturally possible to adjust the melt flow rate by using a mixture of two or more types. Among them, ethylene vinyl acetate copolymer is preferred; The vinyl acetate content of |≦~33% by weight is most suitable.

When the content is less than |≦% by weight, the solubility in organic solvents decreases, the viscosity of the coating ink increases, it becomes more likely to gel, and the workability during production decreases. 33
If it is larger than % by weight, trailing tends to occur, which is not preferable.

In the above, melt flow rate (MFR) and vinyl acetate content (VA) are defined in accordance with JIS K6730.

Furthermore, it is effective to add a resin generally called a tackifier, if necessary, in order to firmly adhere the recorded image to the recording medium.

Tackifiers include coumaron indene resin, phenol/formaldehyde resin, polyterpene resin, xylene/formaldehyde resin, polybutene, rosin pentaerythritol ester, rosin glycerin ester, hydrogenated rosin, hydrogenated rosin methyl ester, and hydrogenated rosin triester. One type or a mixture of two or more types selected from ethylene glycol ester, hydrogenated rosin pentaerythritol ester, polymerized rosin ester, aliphatic petroleum resin, alicyclic petroleum resin, synthetic polyterpene, pentagene resin, etc. is used.

The melting point (m
p+) and the melting point (mpz) of the thermofusible resin, l mp 2
By establishing the relationship -mp Hl≦10, it is possible to reduce "sticking", which is one of the problems of the conventional double-density recording method. This can be inferred to be due to the following reasons.

FIG. 7 shows conventional thermal transfer recording without relative speed.

FIG. 7(a) is a schematic diagram during recording, and FIG. 7(b) is an enlarged diagram schematically showing the force acting on the ink material when heat is applied.

Referring to FIG. 7(b), if there is no relative velocity,
When the heat-sensitive transfer material 1 receives heat from a heating element, at least the surface layer or the entire ink layer of the heat-transferable ink layer 1b exhibits transferability (including adhesive force and penetrating force) to the recording medium. manifest. After applying heat, when the thermal transfer material 1 and the recording medium 2 are separated, the force acting on the thermal transfer ink layer 1b is a shear force FL in the thickness direction of the ink layer.

However, in the double-density recording shown in FIG. 8, the force that acts upon peeling is a shearing force Fl in the plane direction of the thermal transferable ink layer. Generally, the thickness of the heat-fusible ink layer of a heat-sensitive transfer material is from several μm to several tens of μm, and the heater dimensions of a thermal head are from several tens of μm to several hundred μm, and the shear force acting on the heat-fusible ink layer is It can be easily understood that F I <: F z.

Therefore, in the conventional method that does not have relative speed, the thermal transfer material l
If it is difficult to peel off the recording medium 2, only a so-called "peeling delay" will occur, and this will not be a major problem.

However, in double-density recording with relative speed, cohesive failure within the thermally transferable ink layer is essential to obtaining a transferred image. If the ink layer does not undergo cohesive failure, so-called "sticking" occurs, the homogeneity of the resulting transferred image is impaired, and some areas where no ink is transferred occur.

The wax component of the heat-melting binder constituting the heat-transferable ink layer softens and melts at a temperature above its melting point, promotes the softening and melting of the resin component, and develops adhesive strength. That is, it can be said that the melting point of the wax component controls the initiation of transfer of the thermally transferable ink layer 1b to the recording medium 2.

However, the wax melting point mp+ and the resin melting point mp2
If there is a large difference in width, even if the wax component softens and melts, there is a limit to promoting the softening and melting of the resin component, and "sticking" is likely to occur without causing cohesive failure in the surface direction of the thermal transferable ink layer. .

In addition, if the melting point mp2 of the resin is lower than the melting point mpl of wax and the difference is large, the start of transfer to the recording medium will depend on the melting point of the resin, so it is recommended to select a resin with a relatively small molecular weight. Preferably, specifically, in the case of the relationship mp(-mp1<-10), the weight average molecular weight is preferably 100,000 or less, more preferably 70,000 or less.

However, in cases other than the above relationship, that is, l mp 2-m
In the case of the relationship p 1 l≦10, the molecular weight is not particularly limited to the above molecular weight.

In the above description, the difference in melting point, melting end temperature, and melting start temperature was measured as follows.

[Measurement device] Differential scanning calorimetry analyzer DSC-7 (manufactured by PerkinElmer) [Measurement conditions] Heating rate = 5°C/min The difference between the melting end temperature and the melting start temperature (expressed as △T) is as follows. I ask. - As an example, Figure 9 shows Rannox FPS.
-7 (manufactured by Yoshikawa Oil Co., Ltd.) measurement results are shown.

Point A in the figure, that is, the peak value of absorption, is taken as the melting point. △T
The intersection of the slope of the peak and the baseline, point B (melting start temperature) and zero point (melting end temperature), are respectively defined as TI and Te, respectively.

ΔT=Te T'+ The thermal transfer ink layer contains a colorant. Examples of colorants include carbon black, nigrosine dye, lamp black, and Sudan black SM.

Fast ◆ Yellow G1 Benzene Yellow, Pigment
Yellow, Indofast Orange, Irgazine Red, Paranitroaniline Red, Toluidine Red, Carmine FB, Permanent Bordeaux FRR, Pigment Orange R1 Lysol Red 2G, Lake Red C10-Damine FB, Rhodamine B Lake, Methyl Bio Red B Lake, Phthalocyanine Blue, Pigment Blue, Brilliant Green B1 Phthalocyanine Green, Oil Yellow GG1 Zapon Fast Yellow 〇〇〇.

Kayaset Y963, Sumiplast Yellow GG, Zabon Fast Orange RR, Oil Scarlet, Sumiblast Orange G1 Orazur Brown G1 Pomelo Fast Scarlet CG, Eisen Spiron Red F4R,
One or a mixture of two or more of conventionally known colorants such as Fastgen Blue 5007, Sudan Blue, and Oil Peacock Blue are used.

The amount of coloring material contained in the ink layer is preferably 1 to 50% by weight, more preferably 5 to 35% by weight, based on the entire ink layer. If the amount of coloring material is less than 1% by weight, the density of the recorded image will be extremely low, and if it exceeds 50% by weight, problems such as an increase in recording energy, a decrease in transferability to the recording medium, and background stains may occur. occurs, which is undesirable.

Conventionally known plastic films, paper, etc. can be used as the base material for the thermal transfer material of the present invention, but since heat is applied many times to the same location on the base material in double-density recording, for example, aromatic polyamide Preferably, materials with high heat resistance such as film, polyphenylene sulfide film, rubber, polyether ether ketone, and condenser paper are used. In addition, polyester film (especially polyethylene terephthalate film, abbreviated as PE), which has been suitably used for thermal transfer materials,
When using a T film, it is preferable to provide a heat-resistant and slippery material on the surface opposite to the ink surface as a back surface treatment. The thickness of the base material is preferably 3 to 20 μm,
Furthermore, 4-12 micrometers is desirable. As long as the material has high strength and heat resistance, it is also possible to use a material as thin as 3 μm or less. Further, excessively thick materials are not preferable because they have poor thermal conductivity.

In producing the thermal transfer material of the present invention, the above-mentioned binder material is dissolved in an organic solvent such as toluene, methyl ethyl ketone, isopropyl alcohol, methanol, xylene, etc., a colorant is mixed therein, and a dispersion machine such as a sand mill is used. The most suitable method is a solvent coating method in which the material is sufficiently dispersed and applied onto the substrate using a coating method such as a bar code or gravure coating. However, after heating the resin above its softening point and dispersing the coloring material, it may be applied using a so-called hot melt coating, or the resin and coloring material may be coated as an aqueous emulsion by adding a dispersant such as a surfactant. It is also possible.

When applying ink to the substrate, apply a single color (e.g. black) to the entire surface.
If colored ink is applied, a single color thermal transfer can be obtained. In addition, multiple color ink layers (for example, cyan ink, magenta ink, yellow ink, blue ink, green ink Alternatively, a thermal transfer material capable of multi-color recording can be obtained by repeatedly applying different colors (such as red ink) and recording so that the colors are overlapped during printing.

The thickness of the ink layer varies depending on the double density, but for example, when n=3 to 8, the dry coating weight is preferably |≦~30 g/rf, and more preferably 16 to 25 g/rf. If the ink layer thickness is less than |≦g/rrr, a sufficient recording density cannot be obtained in double-density recording, and if it exceeds 30 g/m, problems such as an increase in the recording energy of the thermal transfer material occur, which is not preferable.

〔Example〕

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

The following materials were dissolved and dispersed using a sand mill to obtain a coating ink, and the coating ink was coated on a back-treated polyester film with a thickness of 6 μm using a wire bar, and dried with hot air. A heat-sensitive transfer material was obtained by forming a heat-transferable ink layer with a coating amount of 16 g/rd.

In the following, Rannox FPS-3, FPL-244 (
(manufactured by Yoshikawa Oil Co., Ltd.) is a compound obtained by adding tolylene diisocyanate to a mixture of behenic acid and stearic acid, which is esterified with pentaerythritol, and a mixture of behenic acid and stearic acid, which is esterified with pentaerythritol. It is a mixture with

Example 1 Example 2 (Thermal transfer material I) (Thermal transfer material ■) (Hereafter the margin) Comparative example 1 (Thermal transfer material ■) Example 4 (Thermal transfer material V) Example 3 (Thermal transfer material ■) Implementation Example 5 (Thermal transfer material ■) Example 6 (Thermal transfer material ■) Example 7 (Thermal transfer material ■) Comparative example 2 (Thermal transfer material Xt) Comparative example 3 (Thermal transfer material xn) Example 8 (Thermal transfer material Material■) Example 9 (Thermal Transfer Material X) Example 10 (Thermal Transfer Material As shown in Figure 2, the recording medium and the thermal transfer material are conveyed so that they have a relative speed, and the conveyance length of the thermal transfer material is less than the conveyance length of the recording medium. It was modified and used as an evaluation machine. The physical conditions of this evaluation machine are as follows.

(1) The thermal head is a thick film type full multi-head of 8 p e I / mm, and the heater size is 100 μm in the main scanning direction and 60 μm in the sub-scanning direction.

(2) The feeding amount of the thermal transfer material is 1≦ compared to the feeding amount of the recording medium.

(3) The feeding directions of the thermal transfer material and the recording medium are opposite.

(4) The recording speed is 25 mm/sec, and the relative speed between the recording medium and the thermal transfer material is 31 mm/sec.
It is 2mm/sea.

(5) The surface heat energy of the thermal head during recording is 22 m j /m po.

As a received image, an image of the Institute of Image Electronics Engineers facsimile test chart No. 2 was output on plain paper (TRW-IA Beck smoothness 220 seconds, manufactured by Jujo Paper Industries), and sticking, trailing, and density uniformity were evaluated.

The evaluation criteria are based on the following:

Background smudge ○ Almost no background smudge △ There is some background smudge, but it can withstand practical use × There is a lot of background smudge, but it is not practical. Conspicuous streaking, not practical Density uniformity (test chart) No. 2 [Uneven streaks in the main scanning direction in part 1 of D] ○ Almost no streaks were observed, and the image was homogeneous.

△ Slight unevenness is observed, but it can be used in practical use. × There is some unevenness in the image, and it cannot be said that the image is homogeneous, and it cannot be used in practical use. White streaks) ○ No white streaks observed △ Minute white streaks found, but acceptable for practical use × White streaks are noticeable and cannot be used for practical use The evaluation results are shown in Table 1.

〔Effect of the invention〕

As is clear from the above results, according to the present invention, background smear, whisker-like transfer, and sticking can be prevented even in double-density recording.
Printing with excellent density uniformity can be obtained.

[Brief explanation of drawings]

1 and 2 are perspective views showing an example of an apparatus used for thermal transfer recording of the present invention. 3 to 6 are schematic diagrams showing the principle of thermal transfer recording of the present invention. FIG. 7 and FIG. 8 are principle diagrams showing the principle of the "sticking" effect of the thermal transfer material of the present invention. FIG. 9 is a graph showing an example of DSC measurement results. l・・・・・・・・・・・・・・・・・・・・・・・・
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Thermal transfer material la・・・・・・・・・・・・・・・・・・
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・・・・・・・・・ Support body lb・・・・・・・・・
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・・・・・・Thermal transferable ink layer 2・・・・・・・・・
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・・・・・・・・・・・・・・・・・・ Recorded object 3
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・・・・・・・・・・・・・・・・・・・・・ Recording head IO・・・・Take-up roller 11・・・・・・・・・・・・・・・・・・・・・・
...Platen roller Capstan roller Pinch roller Motor spring: Thermal transferability A: Thermal transferability A: Thermal transferability A: Thermal transferability Thickness of the ink layer Cohesion in the thickness direction of the ink layer Cohesive force in the plane direction of the force layer Heating part of the layer

Claims (5)

[Claims] (1) In a heat-sensitive transfer material having a heat-transferable ink layer containing a heat-melting binder on a support, the heat-melting binder contains at least a wax component and a resin component, and the melting point of the wax component is mp_1 and the melting point mp_2 of the resin component is |mp_2-mp_1|≦10°C. A thermal transfer recording method characterized in that the distance that is moved relative to the recording head is shorter. (2) A heat-sensitive transfer material having a heat-transferable ink layer containing a heat-fusible binder on a support, wherein the heat-fusible binder comprises at least an isocyanate polymer of higher fatty acid pentaerythritol ester, and optionally a higher fatty acid polyester. Using a thermal transfer material consisting of a wax component containing a alcohol ester and a resin component, and in which the melting point mp_1 of the wax component and the melting point of the resin component satisfy the relationship |mp_2-mp_1|≦10°C, A thermal transfer recording method characterized in that the distance that the thermal transfer material moves relative to the recording head is shorter than the distance that the recording medium moves relative to the recording head. (3) The thermal transfer recording method according to claim (2), wherein a thermal transfer material in which the content of the wax component is 20 to 75% by weight based on the binder is used. (4) A heat-sensitive transfer material having a heat-transferable ink layer containing a heat-melt binder on a support, wherein the heat-melt binder is at least an isocyanate polymer of higher fatty acid pentaerythritol ester, and optionally a higher fatty acid polyvalent A thermal transfer material comprising a wax component containing an alcohol ester and a resin component, and characterized in that the melting point mp_1 of the wax component and the melting point mp_2 of the resin component satisfy the relationship |mp_2-mp_1|≦10°C. . (5) The thermal transfer material according to claim (4), wherein the content of the wax component is 20 to 75% by weight based on the binder.