JPS61228992A - Thermal transfer medium - Google Patents

Abstract

PURPOSE:To enable image to be transferred with high image quality irrespectively of the surface condition of a transfer recording paper, by a method wherein a heat-fusible ink is constituted of a coloring agent, a wax, a thermoplastic resin and an adhesiveness-giving resin, and the viscosity of the ink at a specified temperature is set in a specified range. CONSTITUTION:The heat-fusible ink layer 22 is provided on a base 21. The ink layer 22 is constituted of a coloring agent, a wax, a thermoplastic resin and an adhesiveness-giving resin. The thermoplastic resin is an ethylene-vinyl acetate resin, an ethylene-acrylic resin, a vinyl acetate resin or the like. The adhesiveness-giving resin is a terpene resin or the like. The viscosity of the ink layer 22 measured at 100 deg.C by a Brookfield viscometer is set to be 150-1,500aPa.s. Accordingly, ink images with high image quality can be transferred even to a transfer recording paper having a Bekk smoothness of 30-40sec without being affected by the surface condition of the paper.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to a thermal transfer medium used in thermal transfer devices such as printers and facsimiles.

"Prior Art and its Problems" Conventionally, as shown in FIG. 2, for example, this type of thermal transfer medium is coated on a film-like base material 11 having a predetermined thickness of about 3 to 12 ILm at a predetermined temperature. It has an ink layer 12 that is thermally melted. This ink layer 12 includes a binder agent made of wax such as carnauba wax, paraffin wax, and ester wax, a coloring agent made of a pigment such as carbon black and/or a dye such as oil black, and turpentine oil, castor oil, etc. It is made up of a fabric softener. To explain the recording operation of this thermal transfer medium with reference to FIG. 3, a thermal head 13 is in contact with the base material 11, and when the thermal head 13 is driven according to a recording signal and that part generates heat, the base material 11 is heated. The ink in the ink layer 12 in the corresponding portion is melted and transferred to the transfer paper 14 as transfer ink 12a. In this way, transfer paper 1
A transfer image corresponding to the recording signal is formed on 4, and can be transferred to transfer paper 14 using plain paper.

However, since the conventional thermal transfer medium as described above impregnates the surface of the transfer paper 14 with thermally molten ink, it is easily affected by the surface of the transfer paper 14.
For example, when the Bekk smoothness of the surface of the transfer paper 14 is less than 30 to 40 seconds, ink application becomes uneven, which causes image quality deterioration. Therefore, by increasing the thickness of the ink layer 12 so that more ink is transferred to one point, the problems of decreased recording quality and blur due to poor ink transfer will be eliminated.

However, on the other hand, blurring becomes larger and the size of one dot becomes larger, which deteriorates resolution and causes deterioration of image quality.

``Object of the Invention'' The object of the present invention is to solve the problems of the prior art described above and to provide a thermal transfer medium that enables high-quality transfer without being affected by the surface of the transfer paper. There is a particular thing.

"Structure of the Invention" In the thermal transfer medium of the present invention, the heat-melting ink is composed of a colorant, a wax, a thermoplastic resin, and a tackifier resin,
It is characterized by a viscosity of 150 to 1500 mPa eS measured by a Brookfield viscometer at 100°C.

Hereinafter, the thermal transfer medium of the present invention will be explained in more detail.

As shown in FIG. 1, the thermal transfer medium according to the present invention basically includes a heat-melting ink layer 22 formed on a base material 21. As shown in FIG. Therefore, although the layer structure is the same as that of the conventional ink layer 22, the composition and characteristics of the ink layer 22 are improved in the present invention.

As the base material 21, for example, a plastic film such as polyethylene, polyester, polyimide, cellophane or the like having a final layer thickness of about 3 to 12 layers, or a capacitor paper is used.

The ink R22 formed on the base material 21 consists of a colorant, wax, a thermoplastic resin, and a tackifying resin.

As the coloring agent, for example, a pigment such as carbon black and/or a dye such as oil black is used.

As the wax, for example, carnauba wax, paraffin wax, ester wax, bees wax, montan wax, candelilla wax, microcrystalline wax, etc. are used.

As the thermoplastic resin, for example, ethylene-vinyl acetate resin, ethylene-acrylic resin, vinyl acetate resin, etc. are used.

As the tackifying resin, for example, terpene resin, alicyclic saturated hydrocarbon resin, etc. are used.

Terpene resins are organic compounds obtained from various plants (rarely animals) that have a carbon number that is a multiple of 5, 5n (n≦2).
From a biosynthetic point of view, it is a resin obtained by polymerizing substances collectively called terpenes, which are thought to be derived from a precursor consisting of n isoprene or impentane. As the terpene resin, for example, Toho Hi-Resin #90J (trade name, manufactured by Toho Oil Resin Co., Ltd.) can be used.Also, the alicyclic saturated hydrocarbon resin is a cyclic saturated hydrocarbon represented by the general formula 〇nH2n. For example, Finton 1300J and Finton 1500J (trade name, manufactured by Hiki Zeon Co., Ltd.) can be used.

Note that components other than those mentioned above, such as a dispersant, may be added to the ink layer 22 as necessary.

The blending ratio of each component is not particularly limited, but when the blending amount of the entire heat-melting ink is 100 parts, the colorant is 1 to 30 parts.
Parts by weight, 30 to 70 parts by weight of wax, 1 to 100 parts by weight of thermoplastic resin
20 parts by weight, preferably 1 to 30 parts by weight of the tackifying resin.

In the present invention, the viscosity of the ink layer 22 at 100°C measured by a Brookfield viscometer is 150 to 150.
0 mPa-S.

The ink layer of conventional thermal transfer media is made by impregnating molten ink into the transfer paper, and the fibers of the transfer paper are considered to be a collection of capillaries, and when the head is pressed, the ink penetration due to pressure is caused by the penetrating force of the capillaries. Considering that the ink penetration depth d is larger, the ink penetration depth d can be expressed by the following formula using the Olson-Bill formula.

d= (Pr2t/4η table (where P is the pressure of the head, r is the capillary radius, t
is the pressing time, and η is the melt viscosity of the ink. ) From the above equation, it can be seen that the penetration depth of the ink increases as the melt viscosity of the ink decreases. In actual transfer paper, the capillary tubes spread not only in the vertical direction but also in the horizontal direction, so the ink spreads in the horizontal direction as well.

In the ink composition of conventional thermal transfer media, the binder agent is only wax, and the wax itself has almost no tackiness, so the viscosity is 150 mPa*S or less. For this reason, the bleeding became large. Furthermore, as the Bekk smoothness of the surface of the transfer paper decreased, the diameter of the m#1 capillary increased, making it easier to bleed. In addition, when the Bekk smoothness of the surface of the transfer paper is less than 30 to 40 seconds, the surface becomes extremely uneven, causing uneven contact between the ink and the surface of the transfer paper, and causing contact with the convex portions of the surface of the transfer paper. Although the ink penetrates into the transfer paper as described above, since the ink cannot contact the recesses on the surface of the transfer paper, the ink cannot be transferred, resulting in uneven ink coverage and deterioration of image quality.

In the present invention, since the ink of the ink layer contains a thermoplastic resin and a tackifying resin in addition to wax as a binder agent, the viscosity is also 150 to 1500 mPa.
The ink itself becomes sticky and the ink becomes as high as O8.
The connections between inks are also growing. Therefore, even if the transfer paper has poor surface smoothness, the ink that has come into contact with the convex portions of the surface will also transfer the ink located in the depressions to the transfer paper side, making the ink coverage uniform. Furthermore, since the viscosity is high, transfer with little bleeding is possible.

“Embodiments of the invention” Example 1 A hot melt ink was manufactured with the following formulation.

25 parts red carnauba wax, 26 parts paraffin wax (melting point 150°F), colorant
Carbon black MA#40J (trade name, manufactured by Mitsubishi Chemical Industries, Ltd.) 15 parts Complementary color agent "Alkali Blue Powder RP-03J (trade name, Orient Chemical Co., Ltd. % formula %) Thermoplastic resin (ethylene-vinyl acetate resin) 10 Part 1 tackifying resin (terpene resin) "High Resin I90"
” (product name, manufactured by Toho Oil Resin Co., Ltd.) 15 parts 1 dispersant “Tsuruspers 20000 J (product
3 part name, manufactured by ICI) ◆Dispersant “Tsuruspers 12000 J”
First, carnauba wax and paraffin wax were melted, and ethylene-vinyl acetate resin and terpene resin "Hi-Resin #90" were dissolved therein.
J and "Carbon Black MA#40J"
After dispersing “Alkali Blue Powder RP-03”,
A hot-melt ink was prepared by dispersing in a ball mill at 100° C. for 8 to 12 hours.

This heat-melting ink was applied to a polyester film (thickness
m) was coated with 4gm-''Jt cloth to produce a thermal transfer medium.

Example 2 A hot melt ink was manufactured with the following formulation.

・Carnauba wax 25 parts ・Ester wax 28 parts
XJ (product name, manufactured by Orient Chemical Co., Ltd.)
5 parts Thermoplastic resin (ethylene-acrylic resin) 1
0 parts tackifying resin (alicyclic saturated hydrocarbon resin) "Finton 1315" (trade name, manufactured by Hiki Zeon Co., Ltd.)
15 parts/Dispersant “Tsurusperse 2”
0000 J (Product name, manufactured by ICI)
3 parts/Dispersant “Tsurusperse 1200”
0 J (Product name, manufactured by IC1)
1 part First, carnauba wax and ester wax were melted, and ethylene-acrylic resin and alicyclic saturated hydrocarbon resin "Finton 1315J" were dissolved therein.
After adding Tsuru Sparse 12000 J and dispersing "Carbon Black MA#32J" and "Special Black EXJ," the mixture was dispersed in a ball mill at 100° C. for 8 to 12 hours to produce a heat-melting ink.

A heat-sensitive transfer medium was prepared by applying 4 g of this heat-melting ink onto a polyester film (thickness: 6 cm) using a wire bar on a hot plate at 100°C.

Example 3 A hot melt ink was manufactured with the following formulation.

-Carnauba wax 25 parts Paraffin wax (melting point 150'F) 28 parts 1 Colorant "Carbon Black MA# 30J (trade name,
(manufactured by Mitsubishi Chemical Industries, Ltd.) 15 parts Complementary color agent "Nigrosine EXJ (trade name, manufactured by Orient Chemical Co., Ltd.)
5 parts Thermoplastic resin (vinyl acetate resin)
10 parts tackifying resin (terpene resin) “I\Iresin AXJ (trade name, manufactured by Toho Oil Resin Co., Ltd.) 15
Part/Dispersant “Tsurusperse 20000 J (Product name,
(Manufactured by IC1) 3 parts Dispersant "Tsurusperse 12000 J (Product name, IC
First, carnauba wax and paraffin wax are melted, and vinyl acetate resin and terpene resin "Hi-Resin AX" are added to the melted carnauba wax and paraffin wax.
After dissolving Tsuru Sparse 20,000 J and Tsuru Sparse 12,000 J, and dispersing Carbon Black MA#30J and Nigrosine EXJ, the mixture was dispersed in a ball mill at 100°C for 8 to 12 hours to form a hot-melt ink. Manufactured.

A heat-sensitive transfer medium was manufactured by applying 4 gs-2 of this heat-melting ink onto a polyester film (thickness: 8 gm) using a wire bar on a hot plate at 100°C.

Comparative example 1 A hot melt ink was manufactured with the following formulation.

・Carnauba wax 20 parts ・Paraffin wax (melting point 155"F) 38 parts Polyethylene wax 10 parts Colorant "Carbon Black MA#44J (trade name, manufactured by Mitsubishi Chemical Industries, Ltd.) 15 parts Complementary color agent "Oil Black" H
BBJ (product name, manufactured by Orient Chemical Co., Ltd.)
5 parts Φ dispersant “Tsurusperse 20000 J (
Product name, manufactured by ICI) 3
1 part dispersant "Tsuruspers 12000 J (product name, manufactured by ICI) 1 part castor oil 10 parts First,
Carnauba wax, paraffin wax and polyethylene wax are melted and added to
00 J and ``Turu Sparse 12000 J,
"Carbon black paste #44" and "Oil black HBB J" were dispersed, castor oil was added thereto, and then dispersed in a ball mill at 100° C. for 8 to 12 hours to produce a heat-melting ink.

This heat-melting ink was applied to a polyester film (thickness 8 JLm) using a wire bar on a hot plate at 100°C.
) was coated with 4 grs-2 to produce a thermal transfer medium.

The viscosity of the heat-melting ink of the heat-sensitive transfer medium obtained in the above Examples and Comparative Examples was measured using a Brookfield viscometer at 100°C. In addition, printing was performed using a thermal transfer typewriter (S-10 manufactured by Canon Co., Ltd.) using Bankpond paper (Beck smoothness 10 to 18) as the transfer paper, and the print quality of the thermal transfer medium was and transferability was evaluated. The results are shown in the table below. The printing quality and ink transferability were sensually evaluated on a five-point scale with 5 being the highest.

"Effects of the Invention" As explained above, according to the present invention, the Bekk smoothness is 3
A high-quality ink image can be transferred even to a receiving paper for 0 to 40 seconds or less without being affected by its surface.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a thermal transfer medium according to the present invention, FIG. 2 is a schematic cross-sectional view showing an example of a conventional thermal transfer medium, and FIG. 3 is a schematic cross-sectional view showing an example of a conventional thermal transfer medium. There is a schematic sectional view 1 shown. In the figure, 21 is a base material, and 22 is a heat-melting ink layer. Figure 3

Claims (4)

[Claims] (1) A heat-sensitive transfer medium having a heat-melt ink layer that melts at a predetermined temperature on a substrate, wherein the heat-melt ink is composed of a colorant, a wax, a thermoplastic resin, and a tackifying resin, A thermal transfer medium having a viscosity of 150 to 1500 mPa·S as measured by a Brookfield viscometer. (2) The thermal transfer medium according to claim 1, wherein the thermoplastic resin is an ethylene-vinyl acetate resin, an ethylene-acrylic resin, or a vinyl acetate resin. (3) The thermal transfer medium according to claim 1 or 2, wherein the tackifying resin is a terpene resin. (4) The thermal transfer medium according to claim 1 or 2, wherein the tackifying resin is an alicyclic saturated hydrocarbon resin.