JPH0725214B2 - Thermal transfer recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is capable of producing a high-resolution printed image not only on paper having high smoothness and excellent thermal transferability at high-density printing and high-speed printing but also low paper. The present invention relates to a thermal transfer recording medium.

[Prior Art] In recent years, the thermal transfer recording method using a thermal head is noise-free, the apparatus is relatively inexpensive and can be downsized, the maintenance is easy, and the printed image is stable. Because of its advantages, it has been widely used. As a thermal transfer recording medium used in such a thermal transfer recording method,
For example, a wax such as a natural wax or a synthetic wax, a coloring agent, a thermoplastic resin, or the like is mixed or laminated on one surface of a base material having excellent thermal conductivity and heat resistance such as a condenser paper or a polyester film, and then heat-treated. It is provided as a meltable color material layer.

However, the above-mentioned conventional thermal transfer recording medium provided with the heat-meltable color material layer is melt-transferred from the heat-meltable color material layer particularly in the transfer in a short heating time such as high-density printing and high-speed printing. However, there is a drawback in that the transfer rate and resolution of the image are not sufficient due to the lack of energy to operate.

Further, in order to improve this, a thermal transfer recording medium provided with a heat-fusible coloring material layer containing a substance having a small melting energy as a main component so as to sufficiently melt-transfer even in a short heating time is conceivable. Has the drawback that it cannot print clearly on paper with low smoothness.

[Problems to be Solved by the Invention] An object of the present invention is to provide a high-resolution printed image not only to paper having high smoothness and excellent thermal transferability during high-density printing and high-speed printing but also to low paper. A thermal transfer recording medium is provided.

[Means for Solving the Problems] The thermal transfer recording medium of the present invention has a melting point of 50 to 100 on a support.
℃, preferably 60 ~ 90 ℃ provided a release layer containing wax as the main component, on which the colorant and melt index 800 ~ 3
000g / 10min, preferably 1000-2000g / 10min ethylene-ethyl acrylate or vinyl acetate copolymer (ethylene content 70-90% by weight) is provided as the main component of the ink layer and the glass transition point is 100. A fixing-improving layer containing at least one styrene- and / or styrene-derivative-based, vinyl-based, or acrylic-based resin having a temperature of ℃ or higher as a main component is sequentially laminated, and the composition of each of these layers has a fine particle structure. Characterize.

Further, in order to improve the adhesiveness of the release layer, a copolymer of ethylene oxide or ethyl acrylate or vinyl acetate having a melting point of 100 ° C. or more and ethylene oxide having a melt index of 10 to 500 g / 10 min between the support and the thermal transfer layer. (Ethylene content 70 to 90% by weight) and an adhesion-improving layer containing a main component are provided.

The layer structure of the thermal transfer recording medium of the present invention will be schematically described as shown in FIGS. 1 and 2. In the figure, 1 is a support, 2 is a release layer, 3 is an ink layer, 4 is fixing property improving ability, 5
Is an adhesive layer.

The oxidized polyethylene wax used in the adhesive layer of the present invention has a melting point of 100 ° C. or higher, preferably 110 to 130 ° C., and preferably a flexible material, and further has a melt index of 10 to 60.
By using 0 g / 10 min of a copolymer of ethylene and ethyl acrylate or vinyl acetate (the content of ethyl acrylate or vinyl acetate is 10 to 30%), the adhesion to the support is improved. Moreover, not only the adhesion to the support is improved by combining the polyethylene oxide wax and the copolymer of ethylene and ethyl acrylate or vinyl acetate, but also the polyethylene oxide wax and the merlt index.
Due to the synergistic effect of a copolymer of 10 to 600 g / 10 min of ethylene and ethyl acrylate or vinyl acetate, the peeling layer on the adhesive layer is easily cut by the thermal energy of the thermal head, and the transferability is excellent.

The mixing ratio of the polyethylene oxide wax and the copolymer of ethylene and ethyl acrylate or vinyl acetate is preferably 90/10 to 30/70 by weight. The thickness of the adhesive layer is 0.05 ~
3.0 μm, preferably 0.5 to 1.5 μm.

Melt index used in the adhesive layer of the present invention is 10 ~
Ethylene-600g / 10min, ethylene content 70-90%
As the vinyl acetate copolymer, EVAFLEX-210 (MI = 400 g / 10 min, VA =, manufactured by Mitsui / Dupont Polychemical Co., Ltd.)
28%), EVAFLEX-220 (MI = 150g / 10min, VA = 28%),
EVAFLEX-250 (MI = 15g / 10min, VA = 28%), EVAFLEX-
310 (MI = 400g / 10min, VA = 25%), EVAFLEX-410 (MI
= 400g / 10min, VA = 19%), EVAFLEX-420 (MI = 150g / 1
0min, VA = 19%), EVAFLEX-450 (MI = 15g / 10min, A
= 19%), EVAFLEX-550 (MI = 15g / 10min, VA = 14%)
Etc.

Further, as an ethylene-ethyl acrylate copolymer having a melt index of 10 to 600 g / 10 min and an ethylene content of 70 to 90%, MEA / Dupont Polychemical Co., Ltd. EEA-704 (MI = 275 g / 10 min, EA = 25%), EEA-707
(MI = 25g / 10min, EA = 17%) etc.

Examples of the oxidized polyethylene WAX include mp Hoechst-Wax PED121 113-118 Hoechst-Wax PED153 115-120 Hoechst-Wax PED521 103-108 Hoechst-Wax PED522 100-105 manufactured by Hekis Co., Ltd. As described above, the adhesive layer of the present invention contains the oxidized polyethylene wax and the main component of ethylene-ethyl acrylate or ethylene-vinyl acetate copolymer, but in addition to these, a heat-meltable substance such as carnauba, Paraffin, montan wax and the like can be mixed.

The release layer of the present invention is provided in order to facilitate the release of the color material layer and the support when the color material layer is melt-transferred,
It is preferable to use a substance which has a peak value in differential thermal analysis of 120 ° C. or less and easily heat-melts into a low-viscosity liquid. Examples of such substances include beeswax, whale wax, candelilla wax, carnauba wax, rice bran wax, montan wax, natural waxes such as ozokerite, paraffin wax, petroleum wax such as microcrystalline wax, and various modified waxes, Examples include hydrogen wax and long-chain fatty acids. The release layer of the present invention has a wax having a melting point of 50 to 90 ° C. as a main component as described above, but may be used as a mixture of ethylene ethyl acrylate or ethylene-vinyl acetate copolymer, if necessary. .

The release layer of the present invention is suitable for high-density printing and high-speed printing because it has a fine particle structure so that it is easy to cut during printing and has excellent transferability and one-dot reproducibility.

The fine particle structure of the present invention is formed by dispersing the above wax in a solvent and applying it. As the solvent, toluene, xylene, ethyl acetate, methyl ethyl ketonan,
Acetone, methanol, ethanol, isopropanol, ethyl cellsoneb, cyclohexanone, etc. can be illustrated.

The size of the fine particles is 0.01 to 0.8 μm, preferably 0.05 to 0.4 μm. (If it is large, the thermal sensitivity will decrease,
If it is too small, the reproducibility of one dot is lowered and the transfer efficiency is lowered. Further, the thickness of the release layer is 0.1 to 10 μm, preferably 1 to 5 μm.

The ink layer of the present invention comprises a colorant and a melt index of 800 to 3
Melt index by containing 000g / 10min, preferably 1000-2000g / 10min ethylene and ethyl acrylate or vinyl acetate copolymer (ethylene content 70-90wt%, preferably 70-85wt%) Is 800 to 3
Since it is as high as 000g / 10min, it melts and flows in a short time so that it easily wets the transferred material, and the content of ethyl acrylate or vinyl acetate in the copolymer is 10 to 30%, so it adheres to paper. Sex is appropriate.

The melt index used in the ink layer of the present invention is 80.
As an ethylene-ethyl acrylate copolymer having an ethylene content of 0 to 3000 g / 10 min and an ethylene content of 70 to 90%, MB-910 (MI = 1100 g / 10 min, EA = 28%) MB manufactured by Nippon Unicar Co., Ltd.
-900 (MI = 1500g / 10min, EA = 23%) and the like.

Melt index 800-3000g / 10min, ethylene content
70-90% ethylene-vinyl acetate copolymer, manufactured by Nippon Unicar Co., Ltd. MB-850 (MI = 800g / 10mi
n, VA = 22%), MB-010 (MI = 1200g / 10min, VA = 25
%), MB-080 (MI = 2500 g / 10 min, VA = 19%) and the like.

The ink layer of the present invention contains the colorant and ethylene-
The main component is ethyl acrylate or ethylene-vinyl acetate copolymer, but styrene-based and / or styrene-derivative-based, vinyl-based, acrylic-based and paraffin-based, polyethylene, candela, carnauba wax and the like can be added as required.

The colorant is preferably an organic or inorganic dye or pigment having suitable properties as a recording material. For example, those having a sufficient coloring density and not discolored by light, heat, humidity, etc. are preferable. Further, it may be a substance which is colorless when not heated, but which develops color when heated, or a substance which develops color when brought into contact with a substance coated on the transfer target.

Specifically, pigments such as carbon black, titanium dioxide, red iron oxide, lake red C, fast sky blue, benzidine yellow, phthalocyanine green, phthalocyanine blue, direct dyes, oil dyes and basic dyes,
Examples include dyes and the like.

The ink layer of the present invention may be obtained by kneading a colorant and the specific copolymer to form a composition, and applying the composition to the surface of the release layer by an appropriate coating method.

As the composition, the colorant and the specific copolymer are contained in the total weight of the colorant in an amount of 1 to 80%, preferably 5%.
Blend to be ~ 30%.

The fine particle structure is formed by dispersing the composition in a solvent and applying the composition. Examples of the solvent include toluene, xylene, ethyl acetate, methyl ethyl ketone, acetone, methanol, ethanol, isopropanol, ethyl cellosolve, cyclohexanone and the like.

The thickness of the ink layer provided as described above is 0.1 μm to 1
About 0 μm is suitable, and preferably 1 μm to 5 μm.

The ink layer of the present invention is suitable for high-density printing and high-speed printing because it has a fine particle structure and is easy to cut during printing and has excellent transferability and one-dot reproducibility.

The size of the fine particles is 0.01 to 0.8 μm, preferably 0.05 to 0.4 μm. If it is large, the thermal sensitivity will decrease,
If it is small, the 1-dot reproducibility and the transfer efficiency are lowered.

The fixing property-improving layer of the present invention is mainly composed of at least one resin of styrene type and / or styrene derivative type, vinyl type and acrylic type having a glass transition point of 100 ° C. or more, and if necessary, paraffin wax, polyethylene wax and can. Waxes such as delilla wax and carnauba wax and P
It is also possible to add thermoplastics such as thermoplastics such as E, PVC, EVA, EEA.

The styrene resin of the present invention is polystyrene having a molecular weight [MW] of 85,000 (Tg 100 ° C), and the polystyrene derivative is poly P-carbomethoxystyrene (Tg 131 ° C), poly P-cyanostyrene (Tg 120 ° C), poly O-methylstyrene. (Tg115 ° C), poly P-methylstyrene (Tg101
℃), poly-2,4-dimethylstyrene (Tg119 ℃), poly-2,
5-Dimethylstyrene (Tg122 ° C), Poly-3,4-dimethylstyrene (Tg102 ° C), PolyP-tert-butylstyrene (Tg118 ° C), PolyPphenylstyrene (Tg138 ° C), PolyP-phenoxystyrene (Tg100 ° C) ), Poly-2,5-difluorostyrene (Tg101 ° C), poly-P-chlorostyrene (Tg128 ° C), poly-2,5-dichlorostyrene (Tg130)
℃), poly 3,4-dichlorostyrene (Tg 138 ℃), poly 2,
6-dichlorostyrene (Tg167 ° C), poly α-vinylnaphthalene (Tg162 ° C), poly α-methylnaphthalene (Tg180
C).

Polyvinyl divinylbenzene (Tg106
℃), polyvinyl formal (Tg105 ℃), polyvinyl cyclohexane (Tg100 ℃), acrylic resin as polymethyl methacrylate (Tg105 ℃), isotactic polymethyl methacrylate (Tg115 ℃), poly t
ert-Butyl methacrylate (Tg107 ℃), polyethylene glycol dimethacrylate (Tg116 ℃), polypentachlorophenyl acrylate (Tg145 ℃), polyphenyl methacrylate (Tg110 ℃), poly P-cyanophenyl methacrylate (Tg150 ℃), poly P-carbo Methoxyphenyl methacrylate (Tg 106 ° C), poly P-cyanophenyl methacrylate (Tg 128 ° C), polymethacrylonitrile (Tg 120 ° C).

The fixing property-improving layer of the present invention has the composition dispersed in a solvent,
When it is formed by coating on the surface of the ink layer, it has a fine particle structure.

Examples of the solvent include toluene, xylene, ethyl acetate, methyl ethyl ketone, acetone, methanol, ethanol, isopropanol, ethyl cellosolve, cyclohexanone and the like.

The thickness of the fixing property improving layer provided as described above is 0.1 μm.
m to 10 μm is suitable, and preferably 1 μm to 5 μm
m.

The fixing property-improving layer of the present invention is suitable for high-density printing and high-speed printing because it has a fine particle structure and thus has not only fixability but also easy cutting during printing, excellent transferability, and excellent one-dot reproducibility.

The size of the fine particles is 0.01 to 0.8 μm, preferably 0.05 to 0.4 μm. If it is large, the heat sensitivity will decrease,
If it is small, the 1-dot reproducibility and the transfer efficiency are lowered.

The support of the thermal transfer recording medium of the present invention includes, for example, plastic films having relatively good heat resistance such as polyester, polycarbonate, triacetyl cellulose, nylon, and polyimide, as well as glassine paper, condenser paper, metal foil, and the like. An example is a composite of materials.

As the composite, for example, an aluminum / paper composite, metal vapor-deposited paper, metal vapor-deposited plastic film or the like can be mentioned. The thickness of the support is preferably about 2 to 15 μm when a thermal head is considered as a heat source for heat transfer, but a heat source capable of selectively heating a heat transferable ink layer such as laser light is used. There is no particular limitation in this case. When using a thermal head, provide a heat-resistant protective layer made of silicone resin, fluorine resin, polyimide resin, epoxy resin, phenol resin, melamine resin, nitrocellulose, etc. on the surface of the support that contacts the thermal head. According to this, the heat resistance of the support can be improved, or a support material which cannot be used conventionally can be used.

In addition to hot-melt coating as a coating method and gravure coating, roll coating, air knife coating, wire bar coating as a solvent coating method, printing methods such as gravure printing, gravure offset printing, and silk screen printing may be used.

EXAMPLES Next, the present invention will be described in more detail with reference to examples.

Example 1 A 3.5 μm-thick polyester film having a heat-resistant layer on its surface (mp74.6 ° C.) Paraffin wax ˜20 parts by weight Toluene ˜80 parts by weight The composition was dispersed by a ball mill and applied by a gravure roll coating method. A release layer having a thickness of 4 μm was formed, and then 1.5 parts by weight of carbon black on the surface thereof ethylene-ethyl acrylate copolymer [MB-910
(Made by Nippon Unicar Co., Ltd., melt index 1100g / 10
min, EA content 28%] 8.5 parts by weight Toluene 90 parts by weight Disperse the composition in a ball mill to form an ink layer with a thickness of 3 μm by the gravure roll coating method, and then poly P-methylstyrene (Tg101 ℃) 5 parts by weight Paraffin wax 5 parts by weight Methyl ethyl ketone 45 parts by weight Toluene 45 parts by weight A composition was dispersed by a ball mill to form a 2 μm thick fixing property improving layer by a gravure roll coating method, thermal transfer recording medium (A). It was created.

Example 2 In the ink layer composition of Example 1, the ethylene-ethyl acrylate copolymer MB-910 was replaced with an ethylene-vinyl acetate copolymer MB-010 [manufactured by Nippon Unica Co., Ltd.], melt index 1200 g / 10 min, A thermal transfer recording medium (B) was prepared in the same manner except that the vinyl acetate content was changed to 25%).

Example 3 Instead of poly P-methylstyrene (Tg 101 ° C.) in the fixing property improving layer composition in Example 1, (3-1) poly P-chlorostyrene (Tg 128 ° C.) to thermal transfer recording medium (C) ( 3-2) Polyvinylcyclohexane (Tg100 ° C) ~ Thermal transfer recording medium (D) (3-3) Polymethylmethacrylate (Tg105 ° C) ~ Thermal transfer recording medium (E) (3-4) Polyethylene glycol dimethacrylate (Tg116 ° C) ~ Thermal transfer recording medium (F) Example 4 A polyester film having a thickness of 3.5 μm provided with a heat-resistant layer on the back side, polyethylene oxide wax (manufactured by Hoechst Co., Ltd.)
(Mp: 113-118 ° C.) 5 parts by weight Ethylene-ethyl acrylate copolymer A-707 (manufactured by Mitsui DuPont Polychemical Co., Ltd.) (melt index 25 g / 10 min, EA content 17%) 5 parts by weight Toluene 90 parts by weight of the composition was dispersed by a ball mill to form an adhesion improving layer having a thickness of 1 μm by a gravure roll coating method, and then a thermal transfer recording medium (G) was formed on the surface with the same constitution as in Example 1.

Example 5 In Example 4, an ethylene-vinyl acetate copolymer was used instead of the ethylene-ethyl acrylate copolymer A-707 in EVA.
FLEX-410 (Mitsui DuPont Polychemical Co., Ltd.)
(Melt index 400g / 10min, vinyl acetate content 19
%) Was used to prepare a thermal transfer recording medium (H) in the same manner.

Example 6 A thermal transfer recording medium was prepared in the same manner as in Example 3 except that the adhesiveness improving layer of Example 4 was provided.

(6-1) Fixing property improving layer of polyvinyl cyclohexane (I) (6-2) Fixing property improving layer of polymethylmethacrylate Thermal transfer recording medium (J) Comparative Example 1 The release layer in Example 1 was hot-melt coated. A thermal transfer recording medium (a) having the same configuration as that of Example 1 was prepared except that the method was changed to form the release layer coating film.

Comparative Example 2 A thermal transfer recording medium (b) having the same constitution as in Example 1 was used except that the release layer and the ink layer were changed to the hot melt coating method in Example 1 and the release layer coating film and the ink layer coating film were formed. Created.

Comparative Example 3 An example except that the release layer, the ink layer, and the fixability improving layer were changed to the hot melt coating method in Example 1 to form the release layer coating film, the ink layer coating film, and the fixability improving layer coating film. A thermal transfer recording medium (c) having the same configuration as that of No. 1 was prepared.

Comparative Example 4 Only the low-melt-index EEA-704 [Mitsui-DuPont Polychemical Co., Ltd.] (melt index 275 g / 10 min, EA = 25%) was used as the ink layer for the ethylene-ethyl acrylate copolymer in Example 1. A thermal transfer recording medium (d) was prepared in the same manner except that

Comparative Example 5 A thermal transfer recording medium having the same constitution as in Example 1 was prepared by using the following materials in place of poly P-methylstyrene (T0101 ° C.) in the fixing property improving layer in Example 1.

(5-1) Polyvinyl chloride (Tg80 ° C) -Thermal transfer recording medium (e) (5-2) Poly tert-butyl acrylate (Tg43 ° C)-
Thermal transfer recording medium (f) (5-3) Polyethylene terephthalate (Tg 70 ° C.)-Thermal transfer recording medium (g) Comparative Example 6 A 3.5 μm thick polyester film having a heat-resistant layer on the back side (mp74.6 ° C.) paraffin wax 45 parts by weight, microcrystalline wax 10 parts by weight, carnauba wax 10 parts by weight, low molecular weight polyethylene 10 parts by weight, carbon black 15 parts by weight and melt index 1200 g / 10 mi
10 parts by weight of ethylene-vinyl acetate copolymer of n was applied by a hot melt coating method to form a first ink layer (3 μm).
m) was formed. Then, on the first ink layer, 45 parts by weight of paraffin wax, 10 parts by weight of microcrystalline wax, 10 parts by weight of carnauba wax, 10 parts by weight of low molecular weight polyethylene, 15 parts by weight of carbon black, and ethylene-vinyl acetate having a melt index of 400 g / 10 min. Copolymer
Thermal transfer recording medium (h) by applying 10 parts by weight by the hot melt coating method to form the second ink layer (2 μm)
It was created.

Comparative Example 7 Comparative Example 3 except that the first ink layer and the second ink layer were respectively dispersed in 900 parts by weight of toluene by a ball mill to form the ink layer by the gravure roll coating method.
A thermal transfer recording medium (i) similar to that was prepared.

Thermal transfer recording medium (A) of the example obtained as described above
(J) and the thermal transfer recording media (A) to (R) of the comparative example were printed with a thermal transfer printer (prototype machine ... heads 18 / mm) at a head energy of 14 mJ / dot and a printing speed of 150 characters / sec. A paper having a Beck smoothness of 25 seconds was used as the transfer paper. . The print results are shown in Table-1.

[Effect] As is clear from the above description, the thermal transfer recording medium of the present invention has excellent thermal transfer properties during high-density printing and high-speed printing, and has high resolution printing not only on paper with high smoothness but also on low paper. You can give an image.

It also has excellent image fixing properties.

[Brief description of drawings]

FIG. 1 and FIG. 2 are views for schematically explaining the layer structure of the thermal transfer recording medium of the present invention. 1 ... Support, 2 ... Release layer, 3 ... Ink layer, 4 ... Fixability improving layer, 5 ... Adhesive layer.

Claims (2)

[Claims] 1. A release layer comprising a wax having a melting point of 50 to 90 ° C. as a main component is provided on a support, and a coloring agent and ethylene having a melt index of 800 to 3000 g / 10 min and ethyl acrylate or vinyl acetate are provided thereon. Copolymer (ethylene content 70-
90% by weight) as the main component, and further the fixing property-improving layer mainly composed of a resin having a glass transition point of 100 ° C. or more is sequentially laminated, and the composition of each layer has a fine particle structure. A thermal transfer recording medium characterized by the above. 2. An oxidized polyethylene wax having a melting point of 100 ° C. or more and a melt index of 10 to 60 between the support and the release layer.
The thermal transfer recording medium according to claim 1, further comprising an adhesive layer containing, as a main component, a copolymer of ethylene and ethyl acrylate or vinyl acetate (ethylene content: 70 to 90% by weight) at 0 g / 10 min.