KR20010044881A - Thermal transfer recording medium - Google Patents

Abstract

PURPOSE: A thermal transfer recording medium is provided, which prevents a damage of a thermal head of a bar cord printer and a facsimile by reducing a static electricity generated during a printing, and reduce a fatigue of an eye by reducing the luster of a thermally transferred image. CONSTITUTION: The thermal transfer recording medium includes a base film(11), and a heat resistant protection layer(12) formed on one surface of the base film, and a non-transfer layer(13) formed on another surface of the base film, and a transfer layer(14) formed on the non-transfer layer in sequence. The non-transfer layer is constituted with a composition including a conductive carbon black whose average diameter is 15-40nm and its DBP absorption is 120-300(cc/100g) and a thermoplastic resin. And the weight ratio of the conductive carbon black to the thermoplastic resin is 80:20 or 20:80.

Description

Thermal Transfer Recording Medium {Thermal Transfer Recording Medium}

The present invention relates to a thermal transfer recording medium, and more particularly, to a thermal transfer recording medium used for a bar code printer, facsimile, computer graphics, etc., particularly with excellent matting effect, low printing noise, and static electricity. It is characterized by reducing the occurrence of.

The conventional thermal transfer recording medium has a structure in which a non-transfer layer and a transfer layer are sequentially formed on a substrate, and the non-transfer layer is composed of a composition including a filler and a binder. In general, inorganic materials such as carbon black, silica, titanium oxide, calcium carbonate, alumina and talc are used as fillers, and powdered organic materials such as acrylic resins, melamine resins, urea resins, silicone resins, and teflon resins have been used as binders. .

The role of the non-transfer layer is to provide a matting effect on the surface of the transferred image to reduce the eye fatigue when reading the output image, and to give antistatic properties to the thermal head of the barcode printer, facsimile, etc. The non-transfer layer of the conventional thermal transfer recording medium not only provides a sufficient matting effect but also does not provide sufficient antistatic property. In addition, the non-transfer layer of the conventional thermal transfer recording medium has a problem that printing noise is very large because it cannot be separated from the transfer layer smoothly.

An object of the present invention is to solve the problem of the conventional thermal transfer recording medium, by reducing the amount of static electricity generated during printing to prevent damage to the thermal head of the barcode printer, facsimile, etc., giving a more excellent matting effect to the thermoelectric By lowering the glossiness of the copied image, it is possible to provide a thermal transfer recording medium which reduces eye fatigue, facilitates separation from the transfer layer, and significantly reduces printing noise.

Figure 1 shows the structure of the thermal transfer recording medium of the present invention.

<Description of Main Parts of Drawing>

11 ... substrate 12 ... heat-resistant protective layer

13 ... Non-transcription layer 14 ... Transcription layer

In order to achieve the object of the present invention, the present invention is sequentially formed on a base film, a heat-resistant protective layer formed on one side of the base material, a non-transfer layer formed on the other side of the base, and the non-transfer layer A thermal transfer recording medium comprising a transfer layer, wherein the non-transfer layer includes conductive carbon black and a thermoplastic resin having an average particle diameter of 15 to 40 nm and a DBP oil absorption of 120 to 300 (cc / 100g). A thermal transfer recording medium comprising a composition is provided.

In general, carbon black is an ultra fine particle of carbon, which is excellent in color, hiding power, coloring power, and durability, and thus is used as a general black pigment, and has a large surface area, absorbs gas, moisture, etc., and the smaller the particle diameter, the greater the oil absorption amount or dispersion. Sex has a deteriorating character.

Therefore, in the case of using carbon black with a simple secondary structure having a large primary particle diameter and a small oil absorption in the non-transfer layer of the thermal transfer recording medium, it is easy to disperse during manufacturing of the non-transfer layer ink, but the antistatic property after forming the coating film is low. The damage cannot be prevented by the static electricity of the thermal head, and the unevenness of the surface of the non-transfer layer decreases the matt effect after thermal transfer, which makes the eye easily tired when reading with the naked eye.

In the case of using a carbon black having a complex structure having a small particle size and a large oil absorption in the non-transfer layer of the thermal transfer layer, it is excellent in antistatic properties after preparing the coating film, but is very difficult to disperse during preparation of the non-transfer layer ink. The viscosity becomes high and a stable ink cannot be obtained.

Therefore, the thermal transfer recording medium according to the present invention has a feature of using carbon black having an average particle diameter of 15-40 nm and a DI oil absorption amount of 120-300 (cc / 100g) as a filler when forming the non-transfer layer. The use of such carbon black prevents damage to the thermal head of a barcode printer or facsimile due to its excellent antistatic property, and provides unevenness to the surface of the non-transfer layer to provide excellent matting effect on images printed after thermal transfer. Not only does the eye get tired when reading, but the separation from the transfer layer is smooth, so that the printing noise is significantly reduced.

The thermal transfer recording medium of the present invention is obtained by heat-resistant coating on one side of a base to form a heat-resistant protective layer, and sequentially forming the non-transfer layer and the transfer layer on the other side of the base.

As the substrate, a polyethylene terephthalate film, a polypropylene film, a polyamide film, a polycarbonate film, and the like are used. Among them, a polyethylene film is mainly used. It is suitable that the thickness of a base material is 2-20 micrometers here.

The heat resistant layer is required to be heat resistant as a part in contact with the tine head. Examples of the material for forming the heat-resistant protective layer include silicone resins, silicone-urethane copolymer resins, silicone-acrylic copolymer resins, polyvinyl butyral resins, melamine resins, epoxy resins, phenol resins, nitrocellulose resins, and the like. In some cases, a compound having two or more reactors such as isocyanate may be used as a crosslinking agent in order to improve heat resistance.

The non-transfer layer is composed of a composition comprising a filler and a binder, in some cases may further comprise a crosslinking agent. At this time, if the thickness of the non-transfer layer is less than 0.2um, the matting and antistatic effect is lowered, and if it exceeds 3um, the thermal sensitivity is poor, so the thickness of the non-transfer layer is preferably 0.2 to 3um.

Here, carbon black is used as a filler for forming the non-transfer layer according to the present invention. Particularly, when the particle diameter of the carbon black is smaller than 15 nm, the conductivity is excellent, but it is very difficult to disperse, making it difficult to make a stable ink and having a high surface gloss. While the gloss of the surface of the non-transfer layer should be lowered by adding filler, when the particle diameter of carbon black is larger than 40 nm, the dispersibility is excellent, but the conductivity is low, and the damage of the tin head cannot be prevented.

In addition, if the absorption of carbon black is less than 120, the secondary structure of carbon black does not develop, so the conductivity is low, and the matting effect cannot be imparted due to lack of irregularities on the surface of the non-transfer layer, whereas If it is larger than 300, the secondary structure of carbon black is developed, so it has excellent conductivity, but since the viscosity of the non-transfer layer ink is very high, a stable ink cannot be made.

As the filler of the non-transfer layer according to the present invention, it is preferable to use carbon black having an average particle diameter of 15 to 40 nm and a DI oil absorption amount of 120 to 300 (cc / 100 g).

Examples of the thermoplastic resin include nitrocellulose, polyester resin, polyurethane, and vinyl chloride-vinylacetate copolymer. Acrylic resin. At least one selected from the group consisting of diallyl phthalate resin, polyvinyl butyral resin is used.

The weight ratio of the conductive carbon black and the thermoplastic resin is preferably 80:20-20:80. If the ratio of the thermoplastic resin is less than 20, the adhesion of the mat layer to the substrate is insufficient, and thus, This is because separation occurs well at the boundary, and when the ratio of the thermoplastic resin is greater than 80, the antistatic effect and the matting effect are deteriorated.

The transfer layer is composed of a colorant, a binder, and a heat-meltable material. When the thickness is less than 2 μm, the blackness of the print image is insufficient, and when the thickness is greater than 7 μm, the thermal sensitivity becomes worse. Therefore, the thickness is preferably 2 μm to 7 μm.

As the colorant, organic or inorganic dyes or pigments are used, for example, carbon black and the like. The transfer layer composition may further include additives such as plasticizers, fillers, antioxidants, if necessary.

As the binder, a thermoplastic resin having a softening point of 50 to 150 degrees may be used. An ethylene-vinylacetate copolymer, an acrylic resin, a polyvinyl resin, a petroleum resin, a polyester resin, a polyurethane resin, a polyacetal resin, a styrene resin, or the like may be used. Used. As the hot melt material, a wax having a softening point of 60 to 130 degrees is generally used. Specifically, for example, paraffin wax, carnauba wax, candelira wax, microcrystalline wax, montan wax, rice wax wax, polyethylene wax and the like are used.

Hereinafter, the thermal transfer recording medium according to the present invention will be described with reference to an embodiment. However, the present invention should not be construed as being limited to the examples.

Example 1

A heat resistant protective layer made of a silicone resin was formed on one surface of the polystyrene terephthalate film (about 4.5 μm thick). Subsequently, a composition for forming a non-transcription layer was applied to the other side of the polystyrene terephthalate film, and then dried at 100 ° C. for 60 seconds to form a 0.5 μm non-transfer layer.

The composition of the composition for forming a non-transfer layer is as follows.

10 parts by weight of carbon black (div. Oil absorption = 170, particle diameter = 21 nm)

10 parts by weight of CA-139 (polyurethane, manufactured by Morton)

S-24000 (dispersant, manufactured by ICI Corporation) 2 parts by weight

Methyl ethyl ketone 78 parts by weight

The non-transfer layer composition was prepared by dispersing in a ball mill for 20 hours.

The thermal transfer recording medium was completed by applying the transfer layer forming composition on the non-transfer layer to form a transfer layer.

The composition of the transfer layer forming composition is as follows.

15 parts by weight of MA100 (carbon: Mitsubishi Corporation)

EVA210 (ethylene-vinylacetate copolymer:

Mitsui DuPont) 10 parts by weight

Carnauba wax 25 parts by weight

40 parts by weight of paraffin wax (Hipponic wax, HNP5)

10 parts by weight rosin

The transfer layer composition was prepared by dispersing for 10 hours at a temperature of 100 degrees in a ball mill.

Example 2

In the composition for forming a non-transcription layer of Example 1, the carbon adsorption amount was 150 and the particle diameter was changed to 25 nm.

Comparative Example 1

In the composition for forming a non-transcription layer of Example 1, it was carried out in the same manner as in Example 1 except that the carbon absorption amount of carbon black was changed to 66 and the particle size was changed to 24 nm.

Comparative Example 2

In the composition for forming a non-transcription layer of Example 1, it was carried out in the same manner as in Example 1 except that the carbon absorption amount of carbon black was changed to 1000 and the particle diameter was 20 nm).

Comparative Example 3

The composition for forming a non-transcription layer of Example 1 was carried out in the same manner as in Example 1 except that the carbon absorption amount of carbon black was changed to 150 and the particle size was changed to 13 nm.

Comparative Example 4

The composition for forming a non-transcription layer of Example 1 was carried out in the same manner as in Example 1 except that the carbon absorption amount of carbon black was changed to 126 and the particle size was changed to 41 nm.

The characteristics of the composition for forming a non-transfer layer according to Examples 1 to 2 and Comparative Examples 1 to 4 and the characteristics of the thermal transfer recording medium made therefrom were evaluated as follows.

The viscosity of the non-transparent layer forming composition was evaluated by measuring the viscosity at room temperature using a Brookfield viscometer, and the dispersibility of carbon black in the non-transcription layer forming layer composition was measured by measuring the permeability with an optical optical densitometer. Evaluated.

The matting effect of the surface of the non-transparent layer was evaluated by measuring the glossiness of the surface of the non-transparent layer. The antistatic property of the non-transparent layer was evaluated by measuring the surface resistance of the non-transparent layer.

By referring to the above-described evaluation method, the thermotransfer of the viscosity, dispersibility, glossiness of the non-transfer layer, the surface resistance of the non-transfer layer and the final thermal transfer medium prepared in Examples 1 to 2 and Comparative Examples 1 to 4 Table 1 shows the amount of static electricity generated when printing to a printer.

division Viscosity of Non-Transfer Layer Composition (cps) Dispersibility of Carbon Black in Compositions for Non-Transfer Layers Surface resistance of non-transparent layer (Ω / □ ² ) Glossiness of Non-Transfer Static electricity generated during printing Example 1 200 Good 10 ⁵ or less 2.5 0.1kv Example 2 300 Good 10 ⁵ or less 2.3 0.2kv Comparative Example 1 100 Good 10 ⁶ 10 6kv Comparative Example 2 15000 Bad 10 ⁵ or less 5.2 0.1kv Comparative Example 3 2000 Bad 10 ⁵ or less 4.5 0.4kv Comparative Example 4 200 Good 10 ⁶ 8 4.0kv

As shown in Table 1, when the particle diameter of the carbon black is 15 to 40 nm and the DI oil absorption amount is 120 to 300 (cc / 100g), the viscosity and dispersibility of the ink of the non-transfer layer are not only good. The glossiness of the surface of the non-transfer layer is excellent, the matting effect is excellent, and the surface resistance of the surface of the non-transfer layer is low, so that the amount of static electricity generated by the printing press is reduced, thereby preventing damage to the thermal transfer head.

In the thermal transfer recording medium according to the present invention, a carbon black having an average particle diameter of 15 to 40 nm and a DI oil absorption amount of 120 to 300 (cc / 100g) is used to form a non-transfer layer. It is possible to prevent damage to the thermal head of the non-transparent layer, and the surface of the non-transfer layer is provided with unevenness, so the matting effect of the printed image after thermal transfer is very excellent, and the eyes are not tired when reading the printed image with the naked eye. Separation is smooth and printing noise is significantly reduced.

Claims (4)

Base film; A heat resistant protective layer formed on one surface of the substrate; A non-transfer layer formed on the other side of the substrate; And a transfer layer sequentially formed on the non-transfer layer, the thermal transfer recording medium comprising: The non-transfer layer is a thermal transfer recording medium consisting of a composition comprising a conductive carbon black and a thermoplastic resin having an average particle diameter of 15 to 40nm and a DIBP oil absorption of 120 to 300 (cc / 100g). The method of claim 1, wherein the non-transfer layer composition has an average particle diameter of 15 to 40nm, and the weight ratio of conductive carbon black and thermoplastic resin of 80:20 to 20:80 having a DBP oil absorption of 120 to 300 (cc / 100g). Thermal transfer recording medium comprising a. According to claim 1 or 2, wherein the thermoplastic resin contained in the non-transfer layer composition is polyurethane, polyester resin, vinyl chloride-vinylacetate copolymer, nitrocellulose resin, acrylic resin, polyvinyl butyral resin and A thermal transfer recording medium selected from the group consisting of diallyl phthalate resin. The thermal transfer recording medium according to claim 1 or 2, wherein the surface resistance of the non-transfer layer is 10 ⁵ Ω / □ ² or less.