JP2566553B2 - Thermal transfer recording medium - Google Patents

Description

TECHNICAL FIELD The present invention provides a clear transfer image without unevenness or blurring, excellent color reproducibility in color recording, and high transparency OH.
The present invention relates to a thermal transfer recording medium which gives a P image.

2. Description of the Related Art Recently, a heat-sensitive transfer recording medium, that is, a heat transfer sheet has been used as a printing system for an apparatus such as a computer or a facsimile. This method using a thermal transfer sheet is an excellent printing method because it does not cause noise, maintenance of the apparatus is easy, and the apparatus can be made smaller and lighter.

The above-mentioned thermal transfer recording medium is one in which a low melting point substance such as wax mixed with a colorant as a binder and a dispersion medium is applied to the surface of a substrate having good thermal conductivity. The transfer paper is aligned with the layers and printing is performed with a thermal head to form a predetermined image on the transfer paper.

In these heat-sensitive transfer recording media, a natural ester wax or paraffin wax which is melted by heating is mainly used as a vehicle for a colorant.

The thermal transfer recording medium on which an ink layer is formed using these vehicles has insufficient transferred image sharpness, and in ordinary color recording, the color is unclear and opaque, and secondary colors and tertiary colors There was a problem in color reproducibility. Further, when printed on an OHP film and projected, the color was dark and unclear.

The present invention solves the above-mentioned problems of the prior art and forms a color image having excellent color image reproducibility suitable for multi-color and full-color recording, particularly excellent clarity of a transferred image, particularly high transparency, high lightness and high saturation. To provide a thermal transfer recording medium that
It is an object of the present invention to provide a thermal transfer recording medium which gives P projection quality, particularly high brightness and saturation.

Structure The structure of the present invention to achieve the above object is a heat-sensitive transfer recording medium having an ink layer that contains a colorant in a vehicle and is melted by heating, on one surface of a heat-resistant substrate. The thing represented by the following general formula,
A thermal transfer recording medium containing a mixed glyceride containing di, tri and glycerides.

General formula (However, R _{1 to} R ₃ represent a linear acid residue having 17 to 41 carbon atoms, an isoacid residue, an antiisoacid residue, and / or an oxyacid residue.) That is, the present invention relates to an ink layer. The mixed glyceride is used as the vehicle component of the.

Also, although the molecule of this compound is not necessarily clear, it has a bulky long chain and an active functional group at its end,
It is considered that the colorant, particularly the organic pigment, has a high dispersibility, and in addition, since it has an indefinite crystal grain shape in the solid state, it enhances the transparency of the ink.

This compound is synthesized by a conventionally known method. That is, esterification is carried out at an arbitrary molar ratio of glycerin and fatty acid to produce monoglyceride, diglyceride and triglyceride.

In selecting this compound, it is necessary to have various physical properties necessary for thermal transfer printing, and in particular, the melting point as one parameter of thermal characteristics is 60 to 130 ° C and the penetration as a parameter of hardness is Those having a value of 0 to 20 are suitable.

As the mixed glyceride satisfying the above-mentioned various physical properties, the number of alcoholic hydroxyl groups of glycerin and the type of fatty acid residue are important.

As a glyceride that is highly dispersible in colorants, tri
It becomes good in the order of di <mono. That is, the contribution of the alcohol residue of glycerin is large. On the other hand, the fatty acid preferably has 8 to 42 carbon atoms, particularly 22 to 42 carbon atoms, and is not a single fatty acid to form an indefinite crystal grain shape in the solid phase, but a mixture of two or more carbon atoms having different carbon numbers It is desirable that the fatty acid is a fatty acid in which a branched chain saturated hydrocarbon is mixed in the straight chain, and as the fatty acid satisfying this, hard lanolinic acid, montanic acid and the like extracted and purified from natural products are suitable.

The composition for lanolin acid is JAOrg.chem.Soc , 42,
As described in 1063 (1965), it is preferable that the low carbon number fatty acid is used in the present invention. For example, LANOX HH-73 manufactured by Yoshikawa Oil Co., Ltd. may be mentioned.

Further, as for montanic acid, acid wax S, LP, SW and the like of Hoechst Co. having a carbon number of 28 to 32 are listed.

The monoglyceride of stearic acid alone does not satisfy the conditions of the present invention, and dispersibility and transparency are not good.

As other vehicle components, conventionally known waxes and resins that are melted by heating are used. To exemplify these, as waxes, carnauba wax, auricurie wax, microcrystalline wax,
Paraffin wax, ceresin wax, montan wax, candelilla wax, shellac wax, agar wax, palm wax, beeswax, low molecular weight polyethylene and the like can be mentioned.

Further, the resins include polyvinyl chloride, polyvinyl acetate, polyvinyl fluoride, polyvinyl butyral, polyvinylidene chloride, polyvinyl alcohol, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, polystyrene, polyethylene. , Ethylene-vinyl acetate copolymer, styrene-butadiene copolymer, acrylonitrile-styrene-butadiene copolymer, cellulose esters, cellulose ethers, petroleum resin and the like.

The colorant is selected from any organic and inorganic pigments or dyes in consideration of heat resistance and weather resistance during use. As the coloring material, a dye which shows a sublimation property upon heating, or a substance which is colorless at normal temperature but develops color when heated, or a substance which develops color when contacted with a substance applied to a transfer target But it's okay. As other additives, oils such as mineral oil and rapeseed oil are used.

Toluene, xylene or the like is used as a diluent when these ink layer compositions are used by dispersing or dissolving them in a solvent.

As an ink layer formed by kneading the above components, the melting point is 40 ° C to 150 ° C, the viscosity at 100 ° C is 10 to 3000 ° C PS,
The penetration is preferably 0.1 to 30.

The above compositions are 1 to 30% colorant and 95 vehicle, respectively.
˜70% and additives 0˜2%, and prepared by dispersing in a suitable solvent or hot melt dispersion.
Such a composition can be applied to a substrate by a known printing coating method to form an ink layer.

As the substrate, any substance may be used as long as it has strength that does not extend or break during use and does not deform or partially melt due to the heat of the recording thermal head. Polyester, polypropylene, aromatic polyamide, polycarbonate, polyimide And other plastic films, glassine paper, condenser paper, form paper, Indian paper and other papers, metal foils and Al-paper composite sheets, which are composites of the above materials, metal evaporated paper or metal evaporated film, etc. Can be used.

Further, it may be heat-treated, such as by forming a heat-resistant resin layer on one surface of the plastic film.

The material to be transferred is not limited at all, but preferably has a high surface smoothness. For example, plastic film, paper, metal, wood, glass, fiber and the like.

Next, the present invention will be described in more detail with reference to examples together with comparative examples, but the present invention is not limited thereto.

The amounts (parts) of each component in the examples are all parts by weight.

Examples 1 to 3 Ink Composition As shown in Table 1 below, Each of these compositions was placed on a ball mill disperser.
It was dispersed for 12 hours to prepare a uniform ink coating liquid.

The ink coating liquid was applied to a polyester film having a thickness of 6 μm by a Meyer bar and dried with hot air at 100 ° C. for 1.5 minutes to obtain a thermal transfer recording medium having an ink layer thickness of 3.0 ± 0.1 μm.

Comparative Examples 1 and 2 Ink coating liquids were prepared in the same manner as in Examples except that the vehicle components in the ink compositions of Examples 2 and 3 were changed as shown in Table 2 below.

The ink layer was formed in the same manner as in the example to obtain a heat-sensitive transfer recording medium.

Test method for each ink a) Printing test Adhesion of synthetic paper as a transfer target paper and polyester film with a transmittance of 95% and a thickness of 75μ to the ink layer surface of the thermal transfer recording medium, and the applied energy to the thermal line head is 0.4 mJ / Recording was performed by applying the head from the substrate side under the conditions of dot (in a head of 8 dots / mm) and pressing pressure of about 500 g / cm ² . The formation of the secondary color was performed under the same conditions and changing the order of color superposition.

b) Ink transparency test 1) Ink transparency The haze meter manufactured by Toyo Seiki Seisaku-sho, Ltd. was used to measure the sample printed on a polyester film. Using the haze (%) obtained as a result, the transparency was calculated by the following formula.

Transparency (%) = 100-Haze When the transparency is 100%, it is clear.

2) Color difference depending on the order of formation of secondary colors It was measured by a color measuring system Σ80 manufactured by Nippon Denshoku Co., Ltd. using a sample printed on synthetic paper.

 The results of each of the above tests are shown in Table 3 below.

Effects As described above, the thermal transfer recording medium of the present invention is excellent in the sharpness of the transferred image, the color reproducibility of the color recording, and the highly transparent OHP image is formed.

In addition, an image in which the change in color tone due to the order of color superimposition in forming the secondary color is small can be formed.

Claims (2)

(57) [Claims] 1. A thermal transfer recording medium having an ink layer containing a colorant in a vehicle and being melted by heating on one surface of a heat resistant substrate, wherein the ink layer is represented by the following general formula. A heat-sensitive transfer recording medium containing a mixed glyceride containing a glyceride, a di-, a tri-glyceride. General formula (However, R _{1 to} R ₃ represent a linear acid residue having 17 to 41 carbon atoms, an iso acid residue, an antiiso acid residue and / or an oxy acid residue.) 2. The heat-sensitive transfer recording medium according to claim ₁ , wherein the fatty acid residues R _{1 to} R _{3 of} the glycerides represented by the general formulas (I) to (III) are lanolin saturated acid residues.