JPH05501525A - thermal transfer ink ribbon - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] thermal transfer ink ribbon In thermal transfer printing, ink is recorded from an ink ribbon that can be transferred under the action of heat. Transfers to materials, especially paper. Ink ribbons suitable for this purpose are made of a carrier material, e.g. It consists of a foil and a heat-sensitive ink layer applied thereon. This ink layer is usually easily A dye pigment, such as a carton, dispersed in a binder, such as a wax, that melts in Contains bomb black.

The heat required to transfer the ink is transferred from the printer in several separate steps. It is supplied via a thermal element that can be used. These are e.g. They are arranged on so-called thermocams in rows or rows.

Good heat transfer onto the ink ribbon and good ink transfer onto the recording support during the printing process. between the print head and the ink ribbon and between the ink ribbon and the recorder to ensure transfer. There must be good contact between the record carrier and the record carrier. It is necessary to have a flat surface. i.e. good dye on the record carrier A clear printed image can be obtained only when it adheres to the surface.

In addition, in order to be able to print on recording media, especially paper with a rough surface, using the thermal transfer printing method, German Patent Application No. 3,416,067 discloses that a readily meltable binder In addition to the microcapsule-shaped coloring agent, a gas that assists ink transfer is added to the heat exchanger. It has been proposed to also incorporate the gas-forming components that arise under the action. this ink ribbon Ink adhesion and print quality on paper with a surface that is not completely flat. improved ink transfer can be achieved. Inside the obtained image point or character Good color purity is observed in the heart. However, this image point or the edge of the character is A surface structure appears, thus resulting in more or less jagged print edges depending on the paper quality .

This is especially true when high resolution is required or when using even rougher paper. Reduces the optical quality of the image.

It is therefore an object of the invention to improve the printing quality on rough paper surfaces and in particular to improve the printing quality on rough paper surfaces and in particular to To provide an ink ribbon suitable for printing on recycled paper partially made from waste paper. There are many things.

This task is at least A carrier, especially a foil, a binder which is meltable or decomposable under the action of heat applied to the surface of a carrier; pigments contained in the powder, at least one other gaseous transferable dye contained in a binder; to gas and heat during decomposition to assist in transferring one ink component onto the record carrier. Solved by an ink ribbon with thermally unstable components synchronized with the ink, which emit It will be decided.

Other embodiments of the invention are described in the dependent claims.

With the ink ribbon according to the invention, on rough paper (rougher or less than 30 Beck seconds) High-quality printed products with high color purity and clear, beautiful outlines that are independent of the paper structure. quality image points or characters can be obtained.

The coloring agent contained in the binder may be a dye pigment and other sublimable dyes. It is a dye. It can be added to the binder without any problems and is also storage stable. Wear. The printing process itself is no longer a binder (including the color pigments contained therein). It is not a purely mechanical transfer of The decomposition of the thermally unstable components is controlled by the energy supply, and the gas generated during this process is presses the binder and the dye pigments contained therein onto the paper surface or record carrier. same Sometimes other dyes are volatilized or sublimated by the heat of decomposition, dyeing the paper surface more deeply in the vapor phase. This infiltration is further assisted by an emitted gas consisting of thermolabile components.

As a result it is no longer necessary to have good contact between the ink ribbon and the record carrier. , and therefore not affected in any way by the surface of the record carrier or paper. The pigment deposits preferentially on the cold paper surface compared to the dissolved binder, causing coloration. Especially when the binder does not reach during the printing process or is not covered by the binder. It also occurs in the image point or character range on the record carrier.

The paper is well colored even in the edge area of the image point at the deepest part of the uneven paper surface. In addition, by appropriately selecting the color of the dye to be transferred in the gaseous state, the color of the printed image can be improved. You can get clarity. For black color pigments, for example, one type of blue tone or The sharpness of the 0 colors is suitable as several other pigments, such as the corresponding pigment pigment mixtures, e.g. Carbon black with Prussian blue, Milori blue or Reflex blue This can also be achieved by adding For other colors or for four-color printing The corresponding color pigments (cyan, magenta, yellow, black) and gaseous transferable dyes are compatible. harmonize with each other. These pigments may be natural organic or inorganic substances, fluorescent dyes The dye can increase the gloss of the printed image.

It is advantageous to use dyes which can be sublimed at temperatures below 200 °C, e.g. 160 °C. Dyes that can be sublimed with C can easily transfer to the gas phase during the printing process, and Sublimation is possible within this range, which is sufficiently stable on Cribbon or does not volatilize. For example, 1Disverse Blue 14" (1-(methylamino) anthraquinone dyes).

Suitable thermolabile components are, for example, those which do not form a gas under the action of light and/or heat. It is chemically decomposed. Compounds of this type are selected, for example, from the group of azo compounds. You can choose. In this case, the azo compound in the mixture by other catalytic components It is also possible to influence the decomposition of a substance in terms of the required temperature and reaction rate. Ru. Very suitable thermolabile compounds are substances that are toxicologically harmless upon decomposition. , for example, liberating only the non-corrosive and smokeless gases Na, CO or COt. . Also, the colorant is not affected by decomposition residues.

Another blowing agent of the so-called azo type is azobis-isobutyronitrile ( AIBN), diazoaminopenzole (DAB), and similar products. Ru. The amount of gas that can be liberated is 100-220 mI/g depending on the blowing agent mixture. The decomposition heat amount is approximately 300 to 900 J/g (reaction enthalpy).

The catalytic component that affects the decomposition temperature of azo compounds is the so-called Kino force ( Kic k e r ), a starter compound or a mixture thereof is used.

These may be made from inorganic compounds such as zinc oxide, hydrazine or activated carbon, e.g. For example, p-dololsulfonyl hydrazide (TSH), penzol sulfonyl hydrazide Drazide (BSH), p, p'-oxybishenzole sulfonyl hydrazide D, dinitrosopentamethylenetetramine (PNPT), zinc chloride Aromatic and non-aromatic hydrazone compounds and sulfonyl compounds such as finates or other organic priming agents. Based on ADC Commercially available solid blowing agent mixtures are also suitable.

These mixtures can be adjusted to a reaction temperature of, for example, 80 to 220°C.

However, walls, ink ribbons or their components are safe for ink ribbons according to the present invention. It is advantageous to use a mixture which has been adjusted to the reaction temperature. This completed ink In Bonn, these mixtures are stable for at least 4 weeks when stored at 50°C. ing.

The structure of the ink ribbon can be constructed in several layers or in a single layer on the carrier. The latter is It is a fine dispersion of solid components as fine as possible in a binder. As a solid component for example colorants such as pigments or carbon black, optionally 10-30% by weight. Components liberating thermolabile gases in admixture with catalytic components, e.g. 5 to 25% by weight of compound/kitsker mixture, as well as gaseous transferable dyes (thermally transferable). (dye) may contain 2 to 5% by weight.

The binder has wax as its main component, which can be hard wax, paraffin or micro The wax is selected from the group of waxes, and is present in the total layer in an amount of about 10-20% by weight. hardness Refined montan wax, ester wax or carnauba wax, for example. Natural waxes such as

This hard solder is modified with other binder ingredients to impart the desired properties to the binder. do. i.e. modified colophonium or hydrogenated hydrocarbon resins as adhesives It contains about 10-20% by weight of a resin such as. Examples of softening wax include oil, fat, or contains a thermoplastic polymer (homo or copolymer) in an amount of 5 to 10% by weight. Ru.

Higher fatty acids and their derivatives such as metal salts, esters or amides such as stearin 3 to 15 weight of acid ester, lauric acid amide or fat amide as other adducts % may be included.

Binder mixtures of this type are known from the prior art and can be mixed with dyes to provide a color filter. It is commercially available as However, they are compatible with blowing agents from a chemical point of view. i.e. the blowing agent must be adjusted to be hydrophilic or hydrophobic, e.g. or catalytic under acidic conditions, and therefore this blowing agent is even more effective in acidic environments. Has a low decomposition temperature.

What is important for the ink ribbon according to the invention is the freezing point of the binder mixture, The point or dropping point is advantageously in a narrow range of 80-95°C.

In order to manufacture the ink ribbon according to the present invention, each of the above components is homogeneously added to a binder. Also disperse. To apply this, the mixture must be heated above the melting point of the binder. is at least 20°C below the reaction temperature of the gas-releasing component or blowing agent mixture. The carrier is made of, for example, PET with a thickness of about 4 μm. B or PBTBl'! (Polyethylene terephthalate or polybutylene terephthalate However, depending on manufacturing conditions, the foil may have a protective layer, the so-called anti-stick The layer thickness of the binder is determined by the doctor and is approximately 3 ~5 μm.

The ink ribbon according to the present invention having this single layer structure has a multilayer structure described below. The ink ribbon according to the present invention is easy to manufacture and has various advantages over other ink ribbons. In addition to the It can also be reused for one or several uses. Especially thermo In the case of ink ribbons for printing with cams (in this case, the ribbon is printed during the printing process itself) constitutes a negative form of paper and is therefore approximately equivalent to a printed paper having an unprinted surface. ), the above fact is particularly advantageous. Also the same Sometimes this "copy" of the printing process is destroyed, and this is especially true for sensitive data. This is important in the case of data.

The single-layer ink ribbon according to the present invention can be recycled by using a scraping blade and applying light pressure. It is also carried out at elevated temperatures, in which case the same temperature limits as during the manufacturing process are applied. . The maximum possible value for regeneration is the area of the unused ink ribbon and the layer containing ink components. or simply on the amount of layer material still available.

However, particularly sharp printed images are obtained with ink ribbons having a multilayer structure. in addition The gas is introduced into another binder layer below the binder layer containing the pigment and dye. The component to be released is placed together with the catalytic component. The above-mentioned upper layer contains the above-mentioned components. This lower layer, which is usually applied directly onto the carrier, is It contains a blowing agent or blowing agent mixture finely dispersed in another binder.

This binder may be an organic polymer or copolymer and is compatible with the blowing agent mixture. For other blowing agents, the same pre-treatment as for single-layer structures should be used. Prerequisites apply, in particular the decomposition temperature, to gaseous transferable dyes as well as to dyes and It is necessary to match the melting point of the binder layer containing the color pigment. Attuned to the material to be printed No other ink properties or colorants are required for this blowing agent layer.

Suitable binders for blowing agent mixtures containing azo groups are ethylene-vinyl acetate copolymers. - (EVA), from which a dispersion is made using water, and a blowing agent mixture is added to this. Approximately 5 to 25% by weight, and 15% by weight for Ikuri, can be stirred in. then gold When the liquid is cold, the thickness is 0. applied on the carrier so that a dry layer of 3 to 2.0 m is formed, This layer is dried within a few seconds at room temperature. With this EVA binder, the used Extremely low compared to PETB and PETB foil and also compared to the wax mixture used. This results in a stable three-layer structure for the ink ribbon. . This is especially true for high-speed printing presses where this type of ink ribbon is exposed to high mechanical loads. That's important.

Next, the present invention will be described in detail below based on two embodiments and two accompanying drawings. Ru. Each drawing shows ink of the present invention having a one-layer structure (Fig. 1) and a two-layer structure (Fig. 2). FIG. 3 is a cross-sectional view of the ribbon.

First embodiment (Figure 2): A blowing agent mixture (borohol (P Vinyl acetate mixed with 10% by weight of orofor ADC-K (manufactured by Bayer AG) An aqueous dispersion of a copolymer consisting of ethylene (EP17, manufactured by Wanker) and ethylene (EP17, manufactured by Wanker) This coating is applied after cooling and with the help of a doctor.After a few seconds layer 3 dries and the layer 3 The thickness is 0.8 μm. This process makes it possible to obtain a layer with highly uniform layer thickness. , its surface roughness only corresponds to the particle size of the blowing agent particles, and it cannot be confirmed with a microscope. It's just that. The onset of decomposition of the blowing agent layer 3 was measured by DSC and at 125°C. The maximum temperature is 148°C.

Layer 4 is applied on top of this layer, which consists of a commercially available color wax (binder mixture and pigment). This includes approximately 5 layers of sublimable dye (e.g. “Disverse Blue 14”). The coating of the 0 layer, in which % of After solidifying the base or binder, the ink ribbon is completed and the adhesion between the layers is extremely high. It is in good condition. When printing experiments using the thermal transfer printing method, rough surface paper (for example, 30 Beck seconds) ), a clear type surface is obtained, and the image points or characters have sharp edges.

Second embodiment (Figure 1) A foaming agent mixture (Porofor VP-KL3) is added to a colored wax mixture (manufactured by Hoechst). -2014 and Porofor ADC-Kl:1 mixture, manufactured by Bayer) 15 weight % and sublimable dye are stirred in at 85°C. Mixture at finely dispersed stage 3.5 μm thick foil 1 with anti-staying coating (PETB, Tray Co., Ltd.) (manufactured by) at 90°C. After solidification, layer 2 consists of 9 layers 1 and 2 with a thickness of 4.2 μm. The mutual adhesion is very good.The decomposition of layer 0 and 2 started at 140"C through DSC. (up to 152°C). Thermal transfer printing experiments with this ink ribbon are always Shows very good print quality with high resolution and sharp edges.

international search report international search report

Claims (1)

[Claims] 1. In an ink ribbon for thermal transfer printing - a carrier, especially a foil, - a binder that is meltable or decomposable under the action of heat applied to the surface of the carrier; pigments contained in the powder, - at least one more gaseous transferable dye contained in the binder; and - gas and heat during decomposition to assist in transferring the ink components onto the record carrier; An ink for thermal transfer printing that has a heat-labile component synchronized with the ink to release Bon. 2. Claim 1, characterized in that the other dye is sublimable. ink ribbon. 3. Another dye is characterized in that it is sublimable at temperatures below 200°C. The ink ribbon according to claim 2. 4. A claim characterized in that the thermolabile component is a compound from the group of azo compounds. The ink ribbon according to one of the items 1 to 3 of the desired scope. 5. A further catalytic component in which the layer regulates the decomposition of the azo compound by time and starting temperature. 5. The ink ribbon according to claim 4, further comprising: 6. gas phase A claim characterized in that one of the components that assists in transition is azodicarbonamide. The ink ribbon according to one of the ranges 1 to 5. 7. It has a single ink support layer on the carrier in which all the ink components are combined. The ink ribbon according to any one of claims 1 to 6, characterized in that: . 8. The sublimation temperature of the other dye is the decomposition temperature of the thermally unstable component (maximum limit of reaction) according to one of the claims 1 to 7, characterized in that it is within the scope of ink ribbon.