JPH0577559A - Thermal transfer recording medium - Google Patents

Abstract

PURPOSE:To provide a thermal transfer recording medium, which is transferred easily by small energy, enables distinct printing even on paper having low smoothness and has excellent image resistance. CONSTITUTION:In a thermal transfer recording medium, in which a first ink layer 3 using heat-fusing fine particles as a main component is formed onto a support and a second ink layer 4 is formed onto the first ink layer 3, the first ink layer 3 is filled with the heat-fusing fine particles, and air gaps are formed among fine particles. Voids of 5-30vol% is proper, wax is employed as the principal ingredient of the heat-fusing fine particles, and wax having the mean particle size of 0.5-3.0mum of fine particles and the rate of penetration of 2 or less at 25 deg.C is preferable. Heat-fusing fine particles of mean particle size of 0.5-3.0mum are included in the first ink layer 3, and heat-fusing fine particles having mean particle size smaller than said mean particle size is contained in the second ink layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer recording medium, and more specifically, it can be easily transferred with a small amount of energy, and is clear even on low-smooth paper (Beck smoothness of 50 to 150 seconds) such as recycled paper. The present invention relates to a thermal transfer recording medium which can be printed and has excellent abrasion resistance of images, particularly a thermal transfer recording medium having excellent performance when used in a high speed bar code printer.

[0002]

2. Description of the Related Art Printing using a thermal transfer recording medium is performed by bringing the thermal transfer recording medium into close contact with a printing sheet by a thermal head.
By heating a desired heating element among a large number of heating elements of the thermal head, the heat-meltable ink portion in contact with the heating element via the support of the thermal transfer recording medium is melted and transferred to the printing paper. It is done by Typical examples of the thermal transfer recording medium used in such a thermal transfer recording system are: (1) one in which a heat-meltable ink layer comprising a colorant and a binder is directly provided on a support,
(2) One in which a heat-meltable ink layer composed of a colorant and a binder is provided on a support via a release layer containing wax as a main component, and the like.

However, when printing is performed on a printing paper with the thermal transfer recording medium of the type (1), the printing paper must have a smoothness of Beck's smoothness of about 1000 seconds or more to obtain a sufficient printing quality. Was not obtained. Also, in order to obtain an appropriate print density, the ink layer itself must contain a large amount of pigment such as carbon black, so that the pigment is exposed on the transfer surface after printing, and when the card is rubbed with a cardboard or finger, or a pen scanner. There is a drawback that the printing paper itself becomes dirty when it is traced with, for example, and when the barcode is printed, it cannot be read.
On the other hand, the thermal transfer recording medium of the type (2) can be easily transferred to the printing paper due to the presence of the peeling layer, and therefore the smoothness of the printing paper is 400 to 500 seconds in terms of Beck's smoothness. Also, good print quality can be obtained.

However, Beck's smoothness is 400 to 5
As the receiving paper for 00 seconds, there are many plain papers coated with a resin or calendered, which are disadvantageous in that they are expensive and high in running cost. Also, (2) above
Since a wax having a relatively large amount of heat absorption is used as the main component used in the release layer of type (1), it is not possible to apply energy that can sufficiently dissolve the release layer to a high-speed printing printer, resulting in printing defects. There is. Further, due to the presence of the peeling layer, the transfer surface after printing does not expose the pigment and the like and exhibits a considerably superior effect on the abrasion resistance as compared with the above (1), but the wax which is the main component of the peeling layer is soft. Therefore, the sufficient effect cannot be obtained.

Various proposals have been made in order to improve the abrasion resistance of images formed using a thermal transfer recording medium. Some of them are illustrated below. 1) An ink containing a colorant, resin particles having a melting point or softening point of 60 to 140 ° C., wax having a melting point or softening point of 70 to 130 ° C., and a water-soluble resin as main components (JP-A-63-45091). ). 2) Those containing solid solution particles containing resin and wax as main components, a colorant and a binder as main components (Japanese Patent Laid-Open No. Sho 63-63).
-84980). 3) First of which main component is styrene resin particles and wax
Layer, a colorant, tackifying resin particles, and an ink layer having a second layer made of wax (JP-A-63-84)
981). 4) Particles composed of a colorant and a thermoplastic resin, wax particles and a water-soluble resin (JP-A-63-8938).
3). 5) Those having first and second ink layers containing heat-meltable fine particles (JP-A-63-51180).

In the thermal transfer recording media described in the above-mentioned prior arts 1) to 4), the boundary between printing and non-printing can be made clear by granulating each material, the transfer layer is easily cut during transfer, and the resolution is high. improves. However, the binding of the layers is not sufficient, causing scumming and the like, and the heat sensitivity and abrasion resistance are insufficient. On the other hand, the prior art 5) is improved in thermal sensitivity, but is not sufficient, and in particular, it is insufficient in terms of high-speed printing compatibility and high-density recording compatibility. Furthermore, it was insufficient in terms of abrasion resistance.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and enables thermal printing with high sensitivity and excellent abrasion resistance of printed images, capable of clear printing even on low-smooth printing paper. It is intended to provide a medium.

[0008]

The first invention of the present invention is as follows:
In a thermal transfer recording medium in which a first ink layer containing heat-meltable fine particles as a main component is provided on a support and a second ink layer is provided thereon, the first ink layer is filled with the heat-meltable fine particles, It is characterized in that voids are formed between the fine particles. The second invention is a thermal transfer recording medium having a first ink layer and a second ink layer containing heat-fusible fine particles on a support, wherein the average particle diameter of the heat-fusible fine particles in the first ink layer is 0.5 to It is characterized by being 3.0 μm.

The present invention will be described in more detail below with reference to the drawings. FIG. 1 is a schematic sectional view of a thermal transfer recording medium 1 according to the first invention. 2 is a film-like support, 3
Is a first ink layer, 4 is a second ink layer, 5 is a heat-resistant protective layer, 6 is a void, and 7 is heat-meltable fine particles.

As the support 2, for example, polyester,
In addition to relatively heat-resistant plastic films such as polycarbonate, triacetyl cellulose, polyamide, and polyimide, cellophane, sulfuric acid paper, glassine paper, condenser paper, metal foil, etc. can be used, and the thickness is about 2 to 15μ.
m, preferably 3 to 10 μm.

The surface of the support 2 in contact with the thermal head (the surface opposite to the surface on which the ink layer 4 is present) is, if necessary, a silicone resin, a fluorine resin, a polyimide resin, an epoxy resin, or phenol. Resin, melamine resin,
By providing the heat resistant protective layer 5 made of a cellulose resin such as nitrocellulose, the heat resistance of the support 2 can be improved, or a support material which cannot be used conventionally can be used.

Waxes are preferable as the heat-meltable fine particles of the first ink layer 3, and particularly waxes having a penetration of 2 or less at 25 ° C., for example, carnauba wax (25 ° C.).
And a candelilla wax (penetration 1 at 25 ° C.) and a lanolin derivative synthetic wax (penetration 2) are preferred. When a wax having a penetration of more than 2 at 25 ° C. is used, the transfer surface after printing is made of a soft material, which causes a problem that the transferred image is disturbed when rubbed with a finger or a pen scanner.

The voids between the fine particles in the first ink layer 3 have a porosity of 5 to 30 vol% with respect to the first ink layer.
The range is preferably As a method of forming the voids 6, for example, the wax is dispersed in a poor solvent (water or the like) to form a granule, which is coated on a support and dried to volatilize the solvent, resulting in a wax containing the void. Particle 7
It is possible to form a first ink layer which is an aggregate of the above.

In this case, the average particle size of the wax is preferably 0.5 to 3.0 μm. When the average particle size of the wax is smaller than 0.5 μm, it is difficult to form the desired voids, and thus the average particle size is high. The sensitivity and the transferability are not sufficiently improved. On the contrary, when the average particle diameter is larger than 3.0 μm, the melting property is deteriorated and voids are generated in the transferred image.
Further, the area in contact with the support becomes small and the layer has a weak adhesive strength, which causes a defect such as ink drop. Further, the thickness of the first ink layer 3 is 0.5 to 5.0 μm, preferably 1.0 to 2.5 μm. If the thickness is less than 0.5 μm, transferability to paper with low smoothness deteriorates, and conversely 5.0 μ
When it exceeds m, transfer failure occurs at low energy.

Further, in the first ink layer 3, if necessary, an elastomer such as rubber, polyvinyl butyral, vinyl chloride-vinyl acetate copolymer resin, nitrocellulose, epoxy resin, ethylene-vinyl acetate copolymer resin, ethylene-α. One or more kinds of resins such as -olefin copolymer resin, α-olefin-maleic anhydride copolymer resin, ethylene-methacrylic acid copolymer resin and ethyl cellulose may be mixed in appropriate amounts.

The second ink layer 4 is a heat-melting layer containing a coloring agent, waxes which are heat-melting materials, and resins as main components. The colorant is appropriately selected from conventionally known dyes and pigments. Examples of the waxes include paraffin wax, microcrystalline wax, oxidized paraffin wax, candelilla wax, carnauba wax, montan wax, ceresin wax, polyethylene wax, oxidized polyethylene wax, castor wax, tallow-hardened oil, lanolin, and wax. Examples thereof include waxy substances such as sorbitan stearate, sorbitan palmitate, stearyl alcohol, polyamide wax, oleylamide, stearylamide, hydroxystearic acid, synthetic ester wax, and synthetic alloy wax.

Examples of resins include polyamide-based, polyester-based, polyurethane-based, vinyl chloride-based, cellulose-based, petroleum-based, styrene-based, butyral-based, and phenol-based resins, as well as ethylene-vinyl acetate copolymers and ethylene. -Acrylic resins are mentioned. These ink layers 4
The ratio of each material that constitutes
Resins = 5 to 50/30 to 90/5 to 50 are suitable.

For the second ink layer 4, in addition to these, well-known fatty acid ester, glycol ester, phosphoric acid ester, plasticizer such as epoxidized linseed oil and oil are added in a small amount (30% or less). I don't care. Second
The ink layer 4 can be formed by applying it in a state of being melted or dispersed in a hot melt or a solvent and drying it, and its thickness is 0.5 to 5.0 μm, preferably 1.0 to 2.5.
μm. If the thickness is less than 0.5 μm, insufficient density or printing defects on low-smoothness paper will occur, and if it exceeds 5.0 μm, transfer failure at low energy will occur.

Further, the heat-fusible material of the second ink layer is contained in the form of fine particles, and the average particle size thereof is made smaller than the mean particle size of the heat-meltable fine particles of the first ink layer, so that the low-smoothness paper can be made high. Sensitive and clear printing is possible.

Next, the configuration of the second invention of the present invention will be specifically described with reference to the drawings. FIG. 2 shows a thermal transfer recording medium in which the first ink layer 3 is provided on the support 2 and the second ink layer 4 is provided thereon, and the first ink layer is heat-meltable fine particles 31.
And a binder 32. Further, the second ink layer comprises a colorant 41, heat-meltable fine particles 42, and a binder 43.

It is important that the average particle diameter of the heat-meltable fine particles 31 in the first ink layer is in the range of 0.50 to 3.00 μm. Furthermore, using heat-meltable fine particles in the second ink layer,
The average particle diameter is smaller than the average particle diameter of the heat-meltable fine particles of the first ink layer, and particularly, the average particle diameter of the heat-meltable fine particles of the second ink layer is preferably in the range of 0.15 to 0.35 μm. .. The average particle size mentioned here is obtained from the particle morphology observed from the cross section of the thermal transfer recording medium. For the cross-section observation, a sample is formed by an ordinary method, and a transmission electron microscope (T
It can be easily done by EM). The particle size of this TEM observation and the particle size of the coating liquid that forms the ink layer are roughly the same. Therefore, it can be appropriately set according to the average particle size in the coating liquid state. The particle size in the coating liquid can be easily measured by LA-700 manufactured by Horiba Ltd. by a laser diffusion method.

Further, it is more preferable that 75 wt% or more of the heat-meltable fine particles in the first ink layer is a particle group having a particle diameter of 0.5 to 3.0 μm. First ink layer, second
As the particle diameter of the heat-meltable fine particles in each of the ink layers deviates from the above range, the problems shown in Tables 1 and 2 below easily occur.

[0023]

[Table 1]

[0024]

[Table 2]

As described above, the effect of improving the sensitivity, the effect of improving the print compatibility with low-smoothness receiving paper, and the like can be obtained by setting the combination of the heat-meltable fine particles in an appropriate relationship. Although its mechanism is not always clear, it is considered as follows. That is, the average particle diameter of the heat-meltable fine particles of the second ink layer is made smaller than the average particle diameter of the heat-meltable fine particles of the first ink layer, and the average particle diameter of the particles of the first ink layer is set to 0.
When the thickness is 50 to 3.00 μm, the flexibility of the entire ink layer can be improved, and the shear strength can be reduced, and the heating at the time of printing can cause the particles of the printing portion in the first ink layer to be fused. A crack occurs at the boundary between the continuous layer portion and the particle portion of the non-printed portion, the portion to be transferred becomes clear, and as a result, it is easily transferred together with the second ink layer, and transfer at low heat energy can also be made good. Can be estimated.

Further, the first one having a particle size of 0.5 to 3 μm is used.
By setting the content to 75 wt% or more of the entire ink layer, it is possible to prevent the occurrence of voids in the transferred image due to coarse particles. The effect of the fine particles of the second ink layer is that the fine particles smaller than the fine particles of the first ink layer are in a densely packed state, and the particles are efficiently melted and fused when heat is applied, so that they are smoothly applied to the receiving paper. It is thought that it can be bonded.

An organic lubricant which is a heat-melting material is used as the main component of the heat-melting fine particles. The organic lubricant preferably has a melt viscosity of 60 cps or less at 100 ° C. in order to improve the fusion property of particles due to heat during printing. If it is 60 cps or more, the fusion of fine particles due to heating during printing becomes insufficient, the boundary between the heated printed portion and the non-printed portion of the first ink layer is not clearly separated, and the heating is not performed. The releasability of the printed portion from the support becomes insufficient. In addition, the second ink layer has poor adhesion to the receiving paper. Therefore, the thermal sensitivity is lowered, voids are generated in the transferred image when printing at high speed or when printing on low smooth paper.

In addition to the above conditions, in order to improve the abrasion resistance of the transferred image, the penetration at 40 ° C. is preferably 4.0 or less. When the penetration is more than 4.0, sufficient mechanical strength cannot be obtained, and when the transferred image is rubbed, the image is disturbed. As the heat-meltable fine particles,
An organic lubricant is used as the main component. Examples of the organic lubricant include natural waxes such as carnauba wax, candelilla wax, rice wax, castor wax and montan wax, and derivatives of 12-hydroxystearic acid, modified polyethylene, α-olefin, maleic anhydride derivative, lanolin wax. Examples thereof include derivatives, amides such as aliphatic amides and aromatic amides. Carnauba wax is particularly preferable in terms of hardness and endothermic properties.

Further, a thermoplastic resin may be appropriately mixed and fused with an organic lubricant and used in a solid solution state. As the thermoplastic resin, various resins having a melting point or a softening point of 70 to 140 ° C. can be used. Examples thereof include acrylic resin, methacrylic resin, styrene resin, vinyl acetate resin, vinyl chloride resin, vinylidene chloride resin, petroleum resin, terpene resin, olefin resin, polyester resin, polyacetal resin, and copolymers thereof.

When the melting point or softening point is lower than 70 ° C., the abrasion resistance of the transferred image in a high temperature environment (30 to 60 ° C.) is deteriorated, and when the melting point or softening point is higher than 140 ° C., high energy is required for thermal transfer recording, and the recording speed is high. Will be delayed, and the life of the thermal head will be shortened.

Further, as the binder for each layer, it is preferable to use an unvulcanized rubber capable of imparting high binding property and flexibility with a small amount. Examples of these unvulcanized rubbers are polyisoprene, polybutadiene, styrene butadiene rubber, nitrile rubber, ethylene propylene rubber, butyl rubber, silicone rubber, fluorine rubber, urethane rubber, etc.
Preferred are polyisoprene, polybutadiene, ethylene propylene rubber, butyl rubber and nitrile rubber. Note that these preferable rubbers have a melting point of 60 ° C to 200 ° C.
belongs to. Further, a thermoplastic resin such as EVA or EEA may be appropriately used. Further, various oil agents can be used as a softening agent for the layer.

When the first ink layer is unvulcanized rubber and heat-meltable fine particles, the ratio of each is preferably in the range of 3 to 30/97 to 70, preferably 5 to 20/95 to 80. If the amount of unvulcanized rubber is 3% or less, a sufficient binding function cannot be obtained, the ink layer may drop off at low temperatures, and abrasion resistance may deteriorate. On the other hand, if it exceeds 30%, the lubricity of the surface of the transferred image is deteriorated so that the effect of improving the wear resistance cannot be obtained, and the peelability of the layer is deteriorated and the thermal sensitivity is deteriorated.

The thickness of the first ink layer is usually 0.5 to 5 μm.
m, preferably 1.0 to 2.5 μm. 0.
If the thickness is less than 5 μm, the above effect cannot be obtained, and the transferability to low smooth paper deteriorates. On the other hand, when it exceeds 5 μm, transfer defects occur at low energy or at high speed printing. The first ink layer is prepared by coating with an ordinary organic solvent dispersion, water dispersion, or emulsion. More preferably, an emulsion having a stable particle size is preferably used.

Next, the second ink layer will be described. As in the conventional case, the second ink layer is composed mainly of a colorant and an organic lubricant which is a heat-melting material, and optionally a low melting point resin. The colorant is appropriately selected from conventionally known dyes and pigments. Specific examples of the organic lubricant are as described above. Low melting point resins include polyamide-based, polyester-based, polyurethane-based, vinyl chloride-based, cellulose-based, petroleum-based, styrene-based, butyral-based, phenol-based resins, ethylene-vinyl acetate copolymers and ethylene-acrylic resins. Resin, terpene resin, etc. are mentioned. The ratio of each of these components is as follows: colorant / organic lubricant / resins =
5-50 / 30-90 / 5-50 (weight) is suitable. The formation of the heat-meltable ink layer is carried out by applying an organic solvent solution or an aqueous dispersion, coating an emulsion, hot-melt coating, or the like. Similarly to the first ink layer, it is preferable to use emulsified heat-meltable fine particles for the second ink layer. The thickness of the ink layer is usually 0.5 to 5
μm, preferably 1 to 2.5 μm. 0.5
When the thickness is less than μm, the optical density is insufficient and voids are generated when transferred to paper with low smoothness, and when it exceeds 5.0 μm, transfer failure occurs when high-speed printing is performed at low energy.

Further, in the first and second ink layers, in addition to the above components, a plasticizer such as fatty acid ester, glycol ester, phosphoric acid ester, epoxidized linseed oil, and a softening agent such as mineral oil, animal oil, vegetable oil, fluid A small amount (30% or less) of oily substances such as paraffin and silicone oil can be added. A colorant may be added to the first ink layer up to 8%. As a support for supporting the above first and second ink layers, polyester, polycarbonate, triacetyl cellulose, polyamide, polyimide or the like having good heat resistance, cellophane, sulfuric acid paper,
Capacitor paper can be used, and if necessary, a heat-resistant layer of silicone resin, fluororesin, polyimide resin, epoxy resin, phenol resin, melamine resin, cellulose resin, etc. on one side (the side that contacts the thermal head) of these supports. May be provided. Further, an intermediate layer may be provided between the first ink layer and the support to improve the adhesive force.

[0036]

EXAMPLES Next, examples and comparative examples will be shown. Parts herein are by weight. Example I-1 Polyethylene terephthalate (PE having a thickness of 4.5 μm)
T) A coating solution of the following first ink layer component is applied onto the film by using a wire bar so that the thickness after drying is about 1.8 μm, and dried with warm air at 60 ° C. to form the first ink layer. Formed. The porosity calculated from the thickness of the first ink layer and the weight is 1
It was 8.4 vol%. First ink layer component Carnauba wax aqueous dispersion (solid content 30%) (average particle size 1.2 μm) 150 parts Butadiene rubber aqueous dispersion (solid content 50%) 10 parts Water 90 parts A coating liquid containing two ink layer components was applied using a wire bar so that the thickness after drying was about 1.2 μm, and dried to form an ink layer.

Second ink layer component Carnauba wax aqueous dispersion (solid content 30%) (average particle size 0.29 μm) 183 parts Candelilla wax aqueous dispersion (solid content 30%) (average particle size 0.18 μm) 67 parts Ethylene-vinyl acetate copolymer water dispersion (solid content 30%) 33 parts Carbon black water dispersion (solid content 20%) 75 parts Surfactant (Reodol TW-S120) 1 part Water 61 parts Methanol 80 parts An electron micrograph of a cross section of the formed thermal transfer recording medium is shown in FIG.
Shown in.

Example I-2 A thermal transfer recording medium was prepared in the same manner as in Example I-1, except that the components of the first ink layer were changed to those of the following first ink layer. The porosity was 12.0 vol%. First ink layer component Carnauba wax: candelilla wax = 7: 3, water dispersion of mixed wax (solid content 30%) (average particle size 0.9 μm) 155 parts Styrene-butadiene rubber water dispersion (solid content) 50%) 7 parts Water 88 parts

Example I-3 A thermal transfer recording medium was prepared in the same manner as in Example I-1 except that the components of the first ink layer were changed to the components of the following first ink layer. The porosity was 15.5 vol%. First ink layer component Carnauba wax: Lanolin derivative synthetic wax = 9: 1, mixed Water dispersion of wax (solid content 30%) (average particle size 1.5 μm) 155 parts Carboxy modified acrylonitrile butadiene water dispersion (solid content) 50%) 10 parts Water 85 parts

Comparative Example I-1 In the process of forming the first ink layer of Example I-1, drying was performed 8 times.
A thermal transfer recording medium was prepared in exactly the same manner as in Example I-1, except that hot air at 5 ° C was used. Porosity is 0%
Met. Reference Example I-1 A thermal transfer recording medium was prepared in exactly the same manner as in Example I-1, except that the first ink layer component was replaced with the following first ink layer component. The porosity was 32.0%. First ink layer component Carnauba wax aqueous dispersion (solid content 30%) (average particle diameter 3.5 μm) 150 parts Butadiene rubber aqueous dispersion (solid content 50%) 10 parts Water 90 parts

Reference Example I-2 A thermal transfer recording medium was prepared in the same manner as in Example I-1, except that the components of the first ink layer were changed to the components of the first ink layer described below. The porosity was 11.0 vol%. First ink layer component Paraffin wax (mp 70 ° C.) (solid content 30%) (average particle size 0.8 μm) 155 parts Styrene-butadiene rubber aqueous dispersion (solid content 50%) 7 parts Water 88 parts For 6 types of thermal transfer recording media, a thermal transfer printer for barcodes (Atech Co., Ltd.) was applied to high-quality paper (made by FSK) with Beck smoothness of about 70 seconds and surface-treated mirror coated paper (made by Kanzaki Paper) of about 4000 seconds. Made by: SWEDOT1
96) under the conditions of 20 ° C. and 60% RH,
Printing was performed by applying standard energy.

The results are shown in Table 3. The evaluation was performed as follows. Transferability: It was evaluated by whether or not the bar code part was clearly printed. ○: The bar code part is clearly printed and transferred. X: The bar code portion is unclearly printed, and some bar codes are not partially transferred. Bar code read rate: Laser check on the bar code part LC-2811 (Symbol Technology)
ies, Inc. (Manufactured by the company), the laser was randomly scanned 100 times, and the number of times the laser could be read was expressed as a percentage. That is, a reading rate of 100% is 100
It shows that the laser could be scanned 100 times to read 100 times, and the bar code was clear. Abrasion resistance (cardboard test): 4c on bar code
An m × 7 cm square cardboard plate was applied, and a load of 1 kgf was applied, and the same place was rubbed 50 times with a love tester for evaluation. ○… The barcode part is almost clean and can be read with a barcode scanner without any problems. ×: The bar code part is very dirty and difficult to read with a bar code scanner.

[0043]

[Table 3] Example II-1 4.5 μm thick polyethylene terephthalate (PE
T) A coating liquid of the following first ink layer component is applied onto the film by using a wire bar so that the thickness after drying is about 1.5 μm, and dried with warm air at 60 ° C. to form the first ink layer. Formed. First ink layer component Carnauba wax emulsion (solid content 30%) 1) (Average particle size 1.25 μm) 150 parts Butadiene rubber latex (solid content 50%) (JSR # 0700, manufactured by Nippon Synthetic Rubber Co., Ltd.) 10 parts 90 parts of water Furthermore, a coating liquid comprising the following second ink layer component was applied on it using a wire bar so that the thickness after drying was about 1.4 μm, and dried at 70 ° C. to form the second ink layer. Formed.

Second ink layer component Carnauba wax emulsion 2) (solid content 30%) (average particle size 0.224 μm) 250 parts Ethylene-vinyl acetate copolymer latex (solid content 30%) (Sumikaflex410 Sumitomo Chemical Co., Ltd.) 33 parts Carbon black aqueous dispersion (solid content 20%) 75 parts Surfactant (Reodol TW-S120) 1 part Water 61 parts Methanol 80 parts A TEM cross-sectional photographic diagram of the formed thermal transfer recording medium is shown in FIG. It was Preparation of Carnauba Wax Emulsion Carnauba Wax Emulsion 1) Carnauba Wax 27 parts Nonionic emulsifier (HLB14) 3.0 parts Water 70.0 parts

After components other than water were mixed and melted at 90 ° C., the remaining hot water was added with stirring and pre-emulsified with a disperser. Then, the mixture was emulsified with a high-pressure homogenizer and quenched with water to obtain an emulsion having the particle size distribution shown in FIG. 5 (the particle size distribution was measured by the above-mentioned apparatus). Average particle size is 1.25μ
It was m. Carnauba wax emulsion 2) Prepared in the same manner as 1) except that the emulsifier of carnauba wax emulsion 1) was an anionic (HLB13) emulsifier and pre-emulsification was sufficiently performed with a disperser.
FIG. 6 shows the particle size distribution. The average particle size is 0.224 μm
Met. Also for Examples II-2 and later, emulsions were prepared by the method of 1) for the first ink layer and 2) for the second ink layer.

Example II-2 A thermal transfer recording medium was prepared in the same manner as in Example 1 except that the first ink layer component in Example II-1 was replaced with the following ink layer component. First ink layer component Carnauba wax 7: candelilla wax = 7: 3 mixed wax emulsion (solid content 30%) (average particle size 1.95 μm) 155 parts Styrene-butadiene rubber latex (solid content 50%) (JSR0561 manufactured by Japan Synthetic Rubber Co., Ltd.) 7 parts Water 88 parts

Example II-3 A thermal transfer recording medium was prepared in exactly the same manner as in Example II-1 except that the first ink layer component in Example II-1 was replaced with the following first ink layer component. First ink layer component Carnauba wax: Lanolin derivative synthetic wax = 9: 1 mixed wax emulsion (solid content 30%) (average particle size 2.10 μm) 155 parts Carboxy modified acrylonitrile butadiene latex (solid content 50%) (JSR0910) Made by Japan Synthetic Rubber Co., Ltd.) 10 parts Water 85 parts

Example II-4 A thermal transfer recording medium was obtained in the same manner as in Example II-1 except that the second ink layer component of Example II-1 was replaced with the following second ink layer component. .. Second ink layer Carnauba wax emulsion (average particle size 0.29 μm) (solid content 30%) 183 parts Candelilla wax emulsion (average particle size 0.18 μm) (solid content 30%) 67 parts Ethylene-vinyl acetate Polymer latex (solid content 30%) (Sumikaflex 401, manufactured by Sumitomo Chemical Co., Ltd.) 33 parts Carbon black aqueous dispersion (solid content 20%) 75 parts Surfactant (Reodol TW-S120) 1 part Water 61 parts Methanol 80 parts

Example II-5 A thermal transfer recording medium was obtained in the same manner as in Example 2 except that the following components were coated as the second layer on the first ink layer of Example II-2. Second ink layer component Carnauba wax / terpene resin (90/10 weight ratio) Emulsion (average particle size 0.32 μm) (solid content 30%) 250 parts Carbon black aqueous dispersion (solid content 20%) 75 parts Interface Activator (Reodol TW-S120) 1 part Oil (polypropylene glycol # 1000) 10 parts Water 84 parts Methanol 80 parts

Example II-6 The second ink layer component of the above Example II-1 was used as the following second ink layer component, and a thickness of 1. was formed on the first ink layer of the Example II-1 by a hot melt coating method. A thermal transfer recording medium was obtained by coating so as to have a thickness of 5 μm. Second ink layer component Carnauba wax 70 parts Ethylene-vinyl acetate copolymer {Smitate KE-10 (Sumitomo Chemical Co., Ltd.)} 10 parts Carbon black {MA-7 (Mitsubishi Carbon Co.)} 15 parts Oil (mineral oil ) 5 copies

Example II-7 A thermal transfer recording medium was obtained by coating the following second ink layer on the first ink layer of Example II-1 to a thickness of 1.4 μm. Second ink layer component Carnauba wax emulsion (average particle size 0.71 μm) (solid content 30%) 250 parts The same composition as the second ink layer component of Example 1 except for the above.

Comparative Example II-1 In the process of forming the first ink layer of Example II-1, drying was performed 8 times.
A thermal transfer recording medium was prepared in exactly the same manner as in Example II-1 except that hot air at 5 ° C was used. The first ink layer became translucent due to the fusion of the particles.

Comparative Example II-2 A thermal transfer recording medium was prepared in exactly the same manner as in Example II-1, except that the first ink layer component in Example II-1 was replaced with the following first ink layer component. First ink layer component Carnauba wax emulsion (solid content%) (average particle size 4.6 μm) 150 parts Butadiene rubber latex (same as in Example 1) (solid content 50%) 10 parts Water 90 parts

Comparative Example II-3 The following first ink layer component was applied onto the same support as in Example II-1 by the hot melt coating method to give a thickness of 3.0 μm.
To obtain a thermal transfer recording medium. First ink layer component Carnauba wax 40 parts Paraffin wax 32 parts Carbon black 15 parts Mineral oil 3 parts Ethylene-vinyl acetate resin {Smitate KE10 (Sumitomo Chemical Co.)} 10 parts

Reference Example II-1 Thermal transfer recording under the same conditions as in Example II-1 except that the portion of the carnauba wax emulsion having a particle size of 0.5 to 3.0 μm in the first ink layer was 53.4%. A medium was prepared. For these 11 types of thermal transfer recording media, recycled paper with a Beck smoothness of about 50 seconds {paper source (manufactured by Ricoh)} and about 4
Light-weight coated paper with a light coating of 00 seconds (made by Kanzaki Paper,
New Age 70) using a thermal transfer printer for barcode (Atech: SWEDOT196), 2
Printing was performed by applying standard energy under the condition of 0 ° C. and 60% RH. The results are shown in Table 4.

[0056]

[Table 4] The evaluation method for each property is the same as in Table 3.

[0057]

The effects of the present invention described above are summarized as follows. Due to the heating for printing, the boundary between the printed portion and the non-printed portion is clearly cut in the first ink layer,
Further, the peeling property from the support in the printing portion is improved, and the second ink layer is efficiently melted to smoothly adhere to the receiving paper, so that printing on low smooth paper is highly sensitive,
In addition, a clear image can be obtained, and a transfer image having excellent abrasion resistance can be obtained by using a heat-meltable material having a specific penetration in the first ink layer and the second ink layer.

[Brief description of drawings]

FIG. 1 is a schematic view of a cross section of an example of a thermal transfer recording medium according to the present invention.

FIG. 2 is a schematic cross-sectional view showing the configuration of another example of the thermal transfer recording medium of the present invention.

FIG. 3 is an electron micrograph showing a particle structure of a cross section of the thermal transfer recording medium of Example I-1.

FIG. 4 is an electron micrograph showing a particle structure of a cross section of the thermal transfer recording medium prepared in Example II-1.

FIG. 5 is a graph showing the particle size distribution of the emulsion used in the first ink layer of Example II-1.

FIG. 6 is a graph showing the particle size distribution of the emulsion used in the second ink layer of Example II-1.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermal transfer recording medium 2 Film-like support 3 1st ink layer 31 1st layer heat-melting fine particle 32 1st layer binder 4 2nd ink layer 41 Colorant 42 2nd layer heat-melting fine particle 43th Two-layer binder 5 Heat-resistant protective layer 6 Voids 7 Wax component particles

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuyuki Maeda 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Kumi Surizaki 1-3-6 Nakamagome, Ota-ku, Tokyo Stock company Ricoh

Claims (11)

[Claims] 1. A thermal transfer recording medium comprising a support, a first ink layer containing heat-melting fine particles as a main component, and a second ink layer provided on the first ink layer, wherein the first ink layer is the heat-melting fine particles. And a void is formed between the fine particles. 2. The thermal transfer recording medium according to claim 1, wherein the void ratio between the fine particles is 5 to 30 vol% with respect to the first ink layer. 3. The main component of the heat-meltable fine particles in the first ink layer is wax, and the fine particles have an average particle size of 0.5 to 3.
The wax has a penetration of 25.
The thermal transfer recording medium according to claim 1 or 2, wherein the thermal transfer recording medium has a temperature of 2 or less at ° C. 4. The thermal transfer recording medium according to claim 1, wherein the second ink layer contains heat-meltable fine particles. 5. The second ink layer contains heat-meltable fine particles, and the second ink layer has a second average particle diameter of the heat-meltable fine particles of the first ink layer.
The thermal transfer recording medium according to claim 1, wherein the heat-meltable fine particles in the ink layer have a small average particle diameter. 6. A thermal transfer recording medium having a first ink layer and a second ink layer containing heat-meltable fine particles on a support, wherein the average particle diameter of the heat-meltable fine particles in the first ink layer is 0.5 to 0.5. A thermal transfer recording medium having a thickness of 3.0 μm. 7. The thermal transfer recording according to claim 6, wherein the second ink layer contains heat-meltable fine particles, and the average particle diameter thereof is smaller than the average particle diameter of the heat-meltable fine particles of the first ink layer. Medium. 8. The thermal transfer recording medium according to claim 7, wherein the heat-meltable fine particles in the second ink layer have an average particle diameter of 0.15 to 0.35 μm. 9. A particle size of 0.5 to 3.0 μm in the first ink layer.
The thermal transfer recording medium according to any one of claims 6 to 8, wherein 75% or more of the heat-meltable fine particles of m are contained. 10. The melt viscosity of the heat-meltable material in the heat-meltable fine particles at 100 ° C. is 60 cps or less, 40 ° C.
The thermal transfer recording medium according to any one of claims 6 to 9, wherein the penetration degree is 4.0 or less. 11. The heat-meltable fine particles contain carnauba wax as a main component.
10. The thermal transfer recording medium according to any one of 10.