JPH03178482A - Thermally transferable recording medium - Google Patents

Abstract

PURPOSE:To obtain a thermally transferable recording medium which has high sensitivity, forms a transferable image having excellent hot press resistance and anti-abrasion properties and also has a long shelf life of the ribbon by specifying the content of carbon black in a thermally transferable recording medium of a specified composition. CONSTITUTION:A peeling-off layer of wax having a melting or a softening point of 70 to 120 deg.C as main component is provided on a support, and a thermally transferable layer composed mainly of a cross linking acrylic resin and carbon black with a glass transition point of more than 15 deg.C and a molecular weight of more than 1 million is provided on the peeling-off layer. In a transferable recording medium of this structure, the content of carbon black is 30 to 200 pts.wt. for 100 pts.wt. of the cross-linking acrylic resin. That is, the peeling- off layer composed mainly of a specific wax is provided on the support, and the thermally transferable layer of a specially formulated blend of specific cross-linking acrylic resin and carbon black is provided on the peeling-off layer. The thermally transferable recording medium with this thermally transferable layer can meet requirements such as anti-abrasion properties, scratch resistance and long shelf life of the ribbon.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a thermal transfer recording medium particularly suitable for clothing price tags.

[Conventional technology]

Conventionally, the thermal transfer layer (ink layer) of a thermal transfer recording medium has an ink layer containing an emulsified resin with a minimum printing temperature of 40°C or higher (Japanese Patent Laid-Open No. 63-5767).
No. 9); containing styrene/methyl methacrylate/butyl acrylate copolymer as the main component (JP-A No. 62-
23779); Transparent image 8M made of a mixture of styrene/methacrylate copolymer and polyvinyl chloride resin! It has an ink layer made of a mixture of styrene/methacrylic ester copolymer/polymethacrylate/polyvinyl chloride resin and a colorant (JP-A-62-179992); transparent protection made of a chlorinated polyolefin resin. There is one having an ink layer made of a mixture of a (meth)acrylic acid ester polymer and a colorant laminated on the layer (Japanese Patent Application Laid-Open No. 63-42891).

However, when conventional ink layers are used for clothing price tags, etc., they have the disadvantage that images bleed or become smeared due to the heat of hot pressing.

That is, in JP-A No. 63-57679, resins with a minimum film-forming temperature of 40°C or higher do not necessarily have good heat resistance;
Blocking, image smearing, and staining occur at around 0°C. Furthermore, emulsions of resins with a high glass transition point (Tg) such as polymethyl methacrylate have a high minimum film forming temperature and are inferior in thermal sensitivity. In particular, hot pressing at 180° C. or higher causes image bleeding and staining. Furthermore, the adhesion to the transfer target is poor, and the image is likely to fall off if rubbed strongly. Furthermore, if a wax with a low melting point is used as a binder, the image will bleed and become stained during hot pressing, making it impossible to use it for price tags for clothing. Also, JP-A-62-23779, JP-A-62
No. 17992 and JP-A No. 63-42891 have the disadvantage that when Tg is increased, hot press resistance improves but sensitivity becomes slower, and when Tg is lowered, sensitivity becomes faster but hot press resistance deteriorates. Also, since chlorinated polyolefin is used for the protective layer, hot press properties are not good.

[Problem to be solved by the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermal transfer recording medium that has high sensitivity, can form transferred images with excellent hot press resistance and abrasion resistance, and has excellent ribbon storage stability.

[Means to solve the problem]

According to the invention, a melting point or softening point of 70 to 1
Provides a release layer mainly made of wax at 20°C.

In a thermal transfer recording medium provided thereon with a thermal transfer layer mainly composed of a crosslinked acrylic resin with a glass transition point of 15°C or higher and a molecular weight of 1 million or higher and carbon black, the content of carbon black is 100% of the crosslinked acrylic resin. There is provided a thermal transfer recording medium characterized in that the amount is 30 to 200 parts by weight.

That is, the main feature of the present invention is that a release layer mainly composed of a specific wax is provided on a support, and a thermal transfer layer containing a specific crosslinked acrylic resin and carbon black in a specific ratio is further provided on top of the release layer. It is in.

A thermal transfer recording medium having such a thermal transfer layer satisfies all requirements for hot press resistance, abrasion resistance, scratch resistance, and ribbon storage stability.

The present invention will be explained in more detail below.

The release layer in the present invention has a melting point or softening point of 70 to 12
Wax at 0°C, such as carnauba wax, montan wax, osichelite, microcrystalline wax, rice wax, ceresin wax, paraffin wax, polyethylene wax, Sasol wax, hydrogenated castor oil, etc., is the main component, and the thickness is 0°C. 1~3μ
m is preferred. Then, it is formed by hot melt coating or by coating a solution dissolved or dispersed in water or an organic solvent.

This release layer improves the transfer efficiency during thermal transfer and provides a clear image. At the same time, a wax layer is formed on the surface of the transferred image, and the action of the wax improves hot press resistance (making it difficult to transfer to other images). and improves wear resistance.

If the melting point or softening point of the release layer is lower than 70° C., thermal energy during transfer is consumed in melting the wax, impairing transfer of the thermal transfer layer. Furthermore, if the melting point or softening point is higher than 120°C, the peelability during transfer will be poor.

The acrylic crosslinked resin has a glass transition point of 15°C or higher, preferably 20 to 50°C.

The molecular weight may be 1 million or more. As the molecular weight decreases, the transferred image becomes less sharp and the sharpness decreases.

A specific example of the acrylic pre-crosslinked resin is LA-444AI manufactured by Hoechst Co., Ltd., 7 g, 25°C, molecular weight of 1 million or more L.
A-443A2 Tg16℃ Molecular weight 1 million or more LA
-443A37g 20°C with a molecular weight of 1,000,000 or more.

Further, any conventionally known carbon black can be used, and the amount used is 30 to 200 parts by weight, preferably 50 to 100 parts by weight, based on 100 parts by weight of the above-mentioned crosslinked acrylic resin. If the amount of carbon black used is less than 30 parts by weight, blocking occurs during ribbon storage, and if it exceeds 200 parts by weight, thermal sensitivity decreases, which is not preferable.

The thickness of the thermal transfer layer in the first aspect of the present invention and the second thermal transfer layer in the second aspect of the present invention is about 1 to 3 mm.

These thermal transfer layers can be formed by applying a coating solution dissolved or dispersed in water or a solvent and drying.

Examples of thermoplastic resins with a Tg of 30°C or higher used in the first thermal transfer layer in the second invention include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, acrylic acid, methacrylic acid, styrene, α-methylstyrene,
Acrylonitrile, methacrylate trile, vinyl chloride,
Examples include vinyl acetal, polymers of vinyl acetal, copolymers thereof, and copolymers with other monomers (vinyl acetate, acrylic, ethylene, etc.). The first thermal transfer layer has a thickness of about 0.2 to 2 μm, and is obtained by coating and drying a coating liquid in which the resin is dissolved or dispersed in water or a solvent.

The support used in the present invention is a plastic film with a thickness of about 3 to 10 μm, such as polyester film, polycarbonate film, polyimide film, wholly aromatic polyamide film, polyether ether ketone film, polysulfone film, etc. .

In addition, a lubricant may be added to the release layer and/or the first thermal transfer layer of the present invention. Particularly preferred are inorganic lubricants and organic lubricants having a melting point of 140°C or higher.

The inorganic lubricant is preferably talc, mica powder, molybdenum disulfide, graphite, etc. and has an average particle size of 0.11-5p, and is preferably added in the range of 5-20p.

The organic lubricant has a melting point of 140°C or higher, and includes lithium stearate, magnesium stearate, calcium stearate, strontium stearate, barium stearate, calcium laurate, barium laurate, lithium 12-hydroxystearate, 12
-Metal soaps such as calcium hydroxystearate and dibasic lead stearate, N,N'-ethylene bis-
12-Hydroxystearamide, N,N'-ethylenebislauric acidamide, N,N'-methylenebisstearamide, N,N'-hexamethylenebisstearamide, N,N'-hexamethylene Examples include N-substituted fatty acid amides such as bisoleic acid amide, N,N'-distearyl adipic acid amide, N,N-distearyl terephthalic acid amide, polytetrafluoroethylene, silicone resin, etc. 1 to 10% by weight It is desirable to add in a range of 2. These are dissolved in the layer forming liquid or used in the form of fine particles of about 0.1 to 5 mm.

〔Example〕

The present invention will be explained below with reference to Examples and Comparative Examples.

Note that parts are parts by weight.

As an example, the following composition solution was applied onto a polyester film having a thickness of 4.5 μm, and a 'JdJ separation having a thickness of 2 μm was provided.

Carnauba wax 10 parts Toluene (dispersed for 24 hours in a ball mill) 90 parts A liquid having the following composition was applied thereon to form a thermal transfer layer having a thickness of one line.

LA-444AI (7g25℃, solid content 30%)80
Section Example 2 In Example 1, the release layer was replaced with the following composition, and the thickness was 1.
A separation layer of 5μ country was provided.

90 parts of carnauba wax A liquid having the following composition was applied thereon to form a thermal transfer layer.

LA-443A3 (Tg 20°C, solid content 30%) thickness 0.8 μ mark 70 parts Example 3 In Example 2, the following composition liquid was applied between the peeling Xi′i layer and the thermal transfer layer, and the thickness was A first thermal transfer layer of 0.5 μm was provided.

Polymethyl methacrylate (7g 105℃) 1
0 parts Methyl ethyl ketone 90 parts Example 4 A solution having the following composition was applied onto the release layer of Example 2 to a thickness of 0.
A first thermal transfer layer of 5 μm was provided.

n-butanol 10 parts water
70 parts of the solution was coated with the following composition to a thickness of 0.5
A second thermal transfer layer of .mu.m was provided.

LA-443A2 (Tg, 16°C, solid content 30%) 70
Comparative Example 1 A comparative thermal transfer recording medium was prepared in the same manner as in Example 1 except that the carbon black dispersion was changed to 20 parts and the thermal transfer layer had a thickness of 2-2.

Comparative Example 2.3 In Examples 2 and 3, the carbon black dispersion was
Comparative thermal transfer recording media were prepared in the same manner as in each example except that the thickness was 1.5 μm.

Comparative Example 4 A comparative thermal transfer recording medium was produced in the same manner as in Example 4, except that the carbon black dispersion was changed to 280 parts and the thickness was 0.3 μm.

Furthermore, in each Example and Comparative Example, the following composition liquid was applied to the opposite side of the support to the side on which the thermal transfer layer was provided, and the thickness was 0.1p.
A stick prevention layer was provided.

Silicone rubber (30%) 10 parts Toluene 90 parts Curing agent 0.1 part or more Using a thermal transfer recording medium prepared as described above, a thermal transfer printer (
Line type head, applied energy 10-25+++j/
mm2), and the following tests were conducted by printing on a transfer sheet.

Hot press test (JIS L 0850) Friction test (JIS L 0849) Scratch test (pencil hardness test) Storage (ribbon) test (The presence or absence of blocking was checked after 24 hours at 60°C in a rolled state.) Results are shown in Table-1. The transfer paper is coated paper (
A smoothness of 1000 seconds) was used.

The surface condition of the thermal transfer layer was examined using a scanning electron microscope.
! The presence of cracks was investigated.

Table 1 Note: Good image clarity: The contrast is clear and the lines are not blurred. And the lines are sharp.

y#,: Lines are not sharp Hot press resistance Good: No change Slightly poor: Slight transfer to cloth Bad: Image bleeding, large transfer to cloth Abrasion resistance Good: No change Bad: Staining occurs Storage Good properties: No ni-blocking, slightly poor ni-blocking, some bad ni-blocking occurred [Effects of the invention] As explained above, the thermal transfer recording medium according to the first aspect of the present invention has good hot press resistance, abrasion resistance, and scratch resistance. It has excellent durability and ribbon storage stability. Further, in the second invention, since the first thermal transfer layer protects the transferred image, the storage stability is further improved.

Claims (2)

[Claims] (1) A release layer mainly made of wax with a melting point or softening point of 70 to 120°C is provided on the support, and on top of that is a pre-crosslinked acrylic resin with a glass transition point of 15°C or higher and a molecular weight of 1 million or more and carbon black. In a thermal transfer recording medium provided with a thermal transfer layer mainly composed of
200 parts by weight of a thermal transfer recording medium. (2) A release layer mainly made of wax with a melting point or softening point of 70 to 120°C is provided on the support, and a substantially colorless release layer mainly made of a thermoplastic resin with a glass transition point of 30°C or higher is provided on the support. 1 thermal transfer layer, glass transition point 15°C or higher, molecular weight 1
In a thermal transfer recording medium provided with a crosslinked acrylic resin of 1,000,000 or more and a second thermal transfer layer containing carbon black as a main component, the carbon black content is 30 to 100 parts by weight based on 100 parts by weight of the crosslinked acrylic resin. 200 parts by weight of a thermal transfer recording medium.