JPH03183589A - Manufacture of thermally transferable sheet - Google Patents

Abstract

PURPOSE:To provide a safe working environment in which the thermally transferable sheet can be manufactured by allowing fine color powder to become melted in wax of melting point within a constant temperature range, then preparing ink by dispersing the wax containing the color in an organic solvent and applying the ink on one surface of a base material at room temperature, and permitting the solvent to evaporate to form a transferrable layer. CONSTITUTION:At least, more than one weight % of color material is dissolved in an organic solvent, and this color material is dye or pigment of fine particle within a molecular weight range of 100 to 600. Wax has a melting point within a room temperature range of upto 90 deg.C and is thermally melted at temperatures above the melting point. Next the color material is mixed into this molten wax, which is in turn, dispersed into an organic solvent to prepare ink. This ink becomes a stable liquid at room temperature without specially heating it as the wax is dispersed in the ink. Consequently, equipment to keep the ink heated at a specified temperature is no longer required and therefore, the organic solvent does not become ignited easily when work is performed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to thermal transfer in which images and characters are transferred to a receiving sheet by heating according to the image information and character information using a thermal head or point-like heat-sensitive means such as a laser. The present invention relates to a method of manufacturing a sheet.

[Prior Art] A hot melt coating method is known as a method for producing a thermal transfer sheet for color images.

This method uses ink in which yellow, magenta, cyan, and black pigments are heated and melted and dispersed together with specific waxes, binders, dispersants, etc. on one side of a base material such as a thin polyester film of about 3.5 to 10 μm. This is a method in which a thermal transfer sheet is prepared by coating, this sheet is superimposed on a receiving sheet, and yellow, magenta, cyan, and black are transferred in this order using the spot heating means to obtain a multicolor image.

However, in the above-mentioned hot melt coating method, when applying ink using a gravure coating machine, for example, there is a risk that the polyester film may shrink due to heating of the roll and wrinkles may occur. Also, the melting point is 1. If wax, binder, dispersant, etc. of O00 or higher is used, the quality of the ink will deteriorate due to the interaction of the wax, binder, dispersant, etc. in the molten state.
There was a problem that these ink components could not be used.

Another method for producing a thermal transfer sheet is to apply ink made by melting pigments, wax, dispersant, etc. together with a highly compatible solvent onto a substrate, and then thermally transfer it to a receiving sheet in the same manner as above. , a solvent coating method between multicolor images has been put into practical use.

Since this method uses a solvent to form the ink, it is easy to adjust the viscosity of the ink (step 11), and it is easy to control the coating temperature, and it is possible to coat uniformly. However, the wax, dispersant, etc. used as the vehicle are compatible with each other. Even if the wax is heated and dispersed in a solvent with good solubility, the viscosity increases as it gels or the waxes react with each other when cooled, so the coating must be applied while heating to 40-60°C. Heating the ink accelerates the evaporation of the solvent, which changes the ink concentration and reduces coating suitability.In addition, the evaporation of the solvent worsens the working environment and increases the risk of fire and explosion. There was a point.

Conventionally, as a manufacturing method for thermal transfer sheets that solves the above problems, printing and coating can be performed without the need for heating by using, for example, a wax that dissolves in a solvent at room temperature as an ink binder component. A method for manufacturing thermal transfer recording paper from which printed matter can be obtained is disclosed (Japanese Patent Publication No. 1
-36439).

Another manufacturing method is to reduce fluctuations in the solid content concentration by coating a coating liquid containing a heat-melting substance containing a coloring material in an organic solvent and then evaporating the organic solvent. However, a method for manufacturing a thermal transfer sheet that enables uniform dispersion of coloring material has been proposed (Japanese Patent Laid-Open No. 1986-1980).
091).

[Problem that Hokumon is trying to solve] However, in the former production method, even if a certain wax is mixed with a solvent along with a hue and additives and a part of it is dissolved, most of the wax is not dissolved. Since the coloring material is merely dispersed in the solvent without being mixed, the coloring material tends to become localized in the transfer ink composition due to changes over time after mixing. For this reason, even if the transfer ink composition is uniformly applied to the substrate, the coloring material contained in the transfer layer on the substrate may not be uniformly distributed, and when thermal transfer is performed, the print or image on the receiving sheet may not be uniformly distributed. There was a problem where so-called white areas () could be seen.

Further, the latter manufacturing method has the drawback that when an adhesive resin is included as a binder in the heat-fusible substance, it also causes white spots. That is, in a transfer ink composition containing a binder resin, the resin itself is soluble in the organic solvent but is not miscible with the wax, so the resin and wax are likely to separate after the organic solvent is evaporated. Particularly when the resin is a hydrophobic polymer, it is mixed into the wax in a dispersed state.

For this reason, wax that has been aged with a coloring material during transfer is easily transferred, but heat-melted resin is transferred to the thermal transfer recording medium after printing is completed. (When separated from the material, it cools down and increases in viscosity, making it difficult to adhere uniformly to the receiving sheet.

The purpose of the present invention is to do it at room temperature without using any heating means!
It is an object of the present invention to provide a method for producing a thermal transfer sheet that can be coated on a material (1) and that can be produced in a safe working environment where there is no risk of ignition of organic solvents or the production of carbonaceous gases.

Another object of the present invention is to provide a method for producing a thermal transfer sheet that can uniformly disperse a coloring material in a transfer ink composition and that does not cause white spots in the transferred image even when transferred to plain paper. be.

[Means for Solving the Problems] In order to achieve the above object, the method for producing a thermal transfer sheet of the present invention provides a method for producing a thermal transfer sheet of the present invention, in which fine particles of a coloring material having a molecular weight of 100 to 600 and dissolving at least 1% by weight in an organic solvent are melted. Room f! L
A process of dissolving in wax at ~90°C, a process of preparing an ink by dispersing the wax containing this coloring material in the solvent, and coating this ink on one side of the base material at room temperature,
The method is characterized by including a step of evaporating the solvent to form a transfer layer.

The coloring material used in the present invention is a fine particle dye or pigment that is dissolved in an organic solvent in an amount of at least 1% by weight and has a molecular weight in the range of 100 to 600.

Dyes include basic dyes, acid dyes, disperse dyes, etc.
For example, rKAYAsET BLUE K-FL (manufactured by Nippon Kayaku), rALKALI BLUE (manufactured by Orient Chemical), rsOT PINK No. 1 (manufactured by Sakudogaya Chemical), and FORON BRILL YELLOW.
6GFL (manufactured by Sandoz)”, rNIGRO3HINE
BASE EX (Orient Chemical)”, r MIC
It is commercially available under product names such as ``ROLITHBLACK'' (manufactured by Ciba-Geigi). Further, fine particles of pigment may be used, for example, rLI.
ONOL BLUEGXI (manufactured by Toyo Ink), rL
IONOL CARMINE 6BA (manufactured by Toyo Ink)
", rLIONOL YELLOW GRN (manufactured by Toyo Ink)".

Furthermore, wax has a melting point in the range of room fA to 90°C,
Examples include natural waxes such as beeswax, carnauba wax, and wood wax, paraffin waxes such as paraffin wax, modified paraffin wax, microcrystalline wax, and polyethylene wax, α-olefin derived waxes, lanolin waxes, and ester waxes. In the present invention, one or more of the above waxes may be used in combination.

Among the above waxes, carnauba wax has excellent transfer efficiency of ink from the substrate, modified paraffin wax which increases viscosity and increases the amount of coating on the substrate, and α which has good dispersibility of coloring material. Preference is given to combinations with olefin-derived waxes. The blending ratio is 1 to 80 parts by weight of carnauba wax, 1 to 80 parts by weight of modified paraffin wax, and 0.5 parts by weight when the total amount of wax is 100 parts by weight.
~40 parts by weight of alpha olefin derived wax.

The wax is heated and melted to a temperature above its melting point to dissolve the coloring material. When there are multiple types of wax, first, only the multiple types of wax are mixed, heated and melted, and then cooled and solidified. Next, after thoroughly kneading this solid material, the coloring material is dissolved in the heated and melted mixture again.

Next, the ink is prepared by dispersing the wax containing the coloring material in an organic solvent. Due to the dispersion of the wax, this ink becomes a stable liquid at room temperature without special heating.

Organic solvents suitable for the present invention include methyl alcohol,
Toluene, ethyl acetate, butyl acetate, ethyl alcohol, butyl alcohol, acetone, benzene, xylene,
Isopropyl alcohol, methyl ethyl ketone, 1.4
Examples include dioxane. The above solvents can be used alone or in combination of two or more. When the wax is a combination of carnauba wax, modified paraffin wax, and alpha-olefin derived wax, 1,4 dioxane is preferred because it dissolves these waxes best.

A dispersant may be added to improve the dispersibility of the wax in an organic solvent.

For 100 parts by weight of the ink of the present invention, 1 to 30 parts by weight of the coloring material, 3 to 50 parts by weight of the wax, 0.5 to 5 parts by weight of the dispersant, and 10 to 99 parts by weight of the organic solvent may be mixed. preferable.

As the transfer substrate of the present invention, a plastic film of about 1 to 25 μm made of polyester, polyimide, polysulfone, polystyrene, vinyl chloride, polycarbonate, etc. can be used.

When overcoating ink on a base material, in order to improve the adhesion of the transfer layer, the surface of the base material before coating is coated with a 0.05 to 0.0. It is preferable to apply an anchor coat with a thickness of 5 μm. In addition, if a heat-resistant layer or lubricant layer such as silicone resin, fluororesin, fluorine-side lubricant or surfactant is provided in advance on the back side of the base material facing the thermal head,
This is preferable since it can prevent sticking (fusion).

The ink is applied to one side of the substrate by air knife coating, reverse roll coating, gravure coating, wire bar coating, or the like.

[Effects of the Invention] As described above, since the ink of the present invention uses a wax having a relatively low melting point, this ink can be coated on one side of a substrate at room temperature. This eliminates the need for equipment to heat the ink to a predetermined temperature, and allows production to be carried out in a safe working environment where there is no risk of organic solvents igniting, and no toxic gases are generated due to evaporation of organic solvents. be able to.

In addition, coloring materials have high solubility in solvents and are transparent without hiding properties in ink or transferred images, so when subtractive color mixing is performed, the previous color is hidden by the color added later, such as with large particle size pigments. never be done.

In particular, since the ink does not contain any adhesive resin such as hydrophilic polymers or hydrophobic polymers, high-resolution prints or images without omission can be obtained on the transferred receiving sheet.

[Example] Next, the present invention will be explained in detail. In addition, "part" used below
means "parts by weight".

<Example 1> On the surface of a polyester film with a thickness of 45 μm on which a heat-resistant layer was previously provided on the back side, 32 ink of each color (yellow, magenta, cyan, black) prepared in the following manner was applied in the following order.
．． The coating was applied to a thickness of 2 μm at room temperature over the entire width of the film in 7 cm increments using a 200-mesh gravure coater. After coating, the ink was dried at 60°C to obtain a thermal transfer sheet.

The ink was prepared by first mixing the following four types of waxes at the same mixing ratio regardless of the type of coloring material, and heating at 90°C to melt the waxes. After cooling (2), the solidified wax was thoroughly kneaded with three rolls, and then heated to 90° C. again to melt the kneaded wax.

Each coloring material was dissolved into melted kneaded wax and thoroughly stirred. Into this, 1.4 dioxane was added to dilute the wax to obtain an ink. This ink was a stable liquid even at room temperature.

(a) Yellow ink/color material FORON BRILL YELLOW 6GFL (
(Made by Sandoz) 30 parts - Refined wax carnauba wax No. 1 (melting point 83.0°C, viscosity at 100°C 115 cP.

Penetration 2.0) (manufactured by Noda Wax) 10.
0 part modified paraffin wax NC-511 (melting point 85
．． Viscosity at 4°C and 100°C: 8.6 eP.

Penetration 7.0) (manufactured by Noda Wax) 4.0 parts α-olefin-induced wax (Riyakaruna PA-3OL) (
Melting point 67-70°C, viscosity at ioo°C 40-50
cP.

Penetration: 2-3) (manufactured by Mitsubishi Chemical Industries) 2. Part O ○ Lanolin wax LAN0X FP-141ON (melting point 70
°C, viscosity at 100 °C 1500-1800 cP.

Penetration 1-2) (manufactured by Yoshikawa Seibu) 2.0 parts Dispersant Tsurusperse 24000 (manufactured by ICI) 1.0 parts Organic solvent 1.4 Dioxane 78.0 parts (b
) Magenta ink/color material SOT PINK No. 1 (manufactured by Odugaya Chemical) 15
Part Wax Refined carnauba wax No. 1 100 parts Modified paraffin wax NC-5114, 0 parts α-olefin derived wax (Riya Carna PA-30L) Lanolin type '7') SLAN0X FP-141
ON・Dispersant Tsurusperse 24000 (manufactured by ICI)・Organic solvent 1.4 dioxane (C) cyan ink・Color material KAYASET BLUE K-FL (Nippon Kasou)
・Wax purified carnauba wax No. 1 modified paraffin wax NC-511α olefin-derived wax (Riya Carna PA-3OL) ”/9 SLAN0X FP-141ON Lanolin-based wax dispersant Tsurusperse 24000 (manufactured by ICI) Organic solvent 1.4 Dioxane 2.0 parts 20 parts 0 parts 10.0 parts 4.0 parts 20 parts 2.0 parts 1.0 parts 79.0 parts (d) Black ink/coloring material NrGRO3HINE BASE EX (manufactured by Orient Chemical) 3.0 Part ALKALI BLUE (manufactured by Orient Chemical) 1.0 part MI
CROLITHBLACK (manufactured by Ciba Geigi) 2.0 parts Wax purified carnauba wax No. 1 100 parts Modified paraffin wax NC-5114, 0 parts α-olefin derived wax (Riya Carna PA-3OL) 2.0
Lanolin wax LAN0X FP-141ON
2.0 parts dispersant Tsurusperse 24000 (manufactured by ICI) 1.0 parts organic solvent 1.4 dioxane 75.0 parts The transfer layer of the above thermal transfer sheet was superimposed on a receiving sheet made of plain paper, and Copper Electric CHC-645
), and when the image information was transferred, colors close to natural images were reproduced, and a high-definition image with no white spots was obtained.

<Example 2> Four types of inks prepared in the same manner as in Example 1 were coated on the surface of a 3.5 μm thick polyester film with a heat-resistant layer on the back surface in advance to form a thermal transfer sheet. I got it.

Three types of waxes except black were mixed at the same mixing ratio regardless of the type of coloring material. In addition, LAN0X of Example 1
Ester wax was used instead of FP-141ON. The ink of Example 2 was also a stable liquid at room temperature.

(a) Yellow ink - Coloring material LIONOL YELLOW GRN (manufactured by Toyo Ink) 2.0 parts - Wax purified carnauba wax No. 1 (melting point 83.0°C, viscosity at 100°C 115cP.

Penetration 2.0) (manufactured by Noda Wax) 7.0 parts modified paraffin wax NC-511 (melting point 85.4°C, 1
Viscosity at 00°C: 8.6 cP.

Penetration 7.0) (manufactured by Noda Wax) 3.0 parts α-olefin-induced wax (Riyakaruna PA-3OL) (
Melting point 67-70℃, viscosity at 100℃ 40-50c
P needle strength 2-3) (manufactured by Mitsubishi Chemical Industries) 1.0 part ester wax Hoechstwafx E (melting point 79-
Viscosity at 85°C and 100°C 20-30cP.

Penetration 1.0) (Hoechst) 2.0 parts Dispersant Tsurusperse 24000 (ICI) 1.0 parts Organic solvent toluene 40.0 parts 1.4 Dioxane 44.0 parts (b
) Magenta ink/Coloring material LIONOL CARMINE 6BA (manufactured by Toyo Ink) 1.8 parts Wax purified carnauba wax No. 1 7.0 parts Modified paraffin wax NC-5113, 0 parts α-olefin derived wax (Riya Carna PA-3OL ) 1.
0 parts ester wax Hoechstwafx E
2.0 parts Dispersant Tsurusperse 24000 (manufactured by ICI) Organic solvent toluene 1.4 dioxane (c) cyan ink Coloring material LIONOL BLUE GXI (manufactured by Toyo Ink)
Carnauba Wax No. 1 modified paraffin wax manufactured by Waxcho NC-511 α olefin derived wax (Riyacarna PA-3OL) Ester wax Hexistwafx E / Dispersant Tsurusperse 24000 (manufactured by ICI) / Organic solvent Toluene 1.4 Dioxane 1.0 parts 40.0 parts 44.2 parts 2.0 parts 7.0 parts 3.0 parts 1.0 parts 2.0 parts 0 parts 40.0 parts 44.0 parts (d) Black ink/color Carbon black (manufactured by Mitsubishi Chemical Industries) 5.0 parts NIG
ROSHINE BASE EX (manufactured by EN Chemical)
20 parts - Wax purified carnauba wax No. 1 6.0 parts Modified paraffin wax NC-5113, 0 parts α-olefin derived wax (Riya Carna PA-3OL) 2.0 parts
Ester-based wax Hoechstwafx E
2.0 parts/Dispersant Tsurusperse 24000 (manufactured by ICI) 1.
0 parts Organic solvent Toluene 40.0 parts 1.4 Dioxane 39.0 parts The transfer layer of the above thermal transfer sheet was superimposed on a receiving sheet made of plain paper, and a thermal transfer printer (CHC-345 manufactured by Shindo Denki Co., Ltd.) was used.
) and transferred a computer graphic design, an image with extremely strong light fastness was obtained in which the seven basic colors were used.

Claims (1)

[Scope of Claims] 1) A step of dissolving a fine particle coloring material having a molecular weight of 100 to 600 dissolved in an organic solvent of at least 1% by weight into a wax having a melting point of room temperature to 90°C, and adding this coloring material to the solvent. A method for producing a thermal transfer sheet, comprising: preparing an ink by dispersing wax containing the ink; and applying the ink to one side of a substrate at room temperature, and then evaporating the solvent to form a transfer layer. . 2) When the total amount of wax is 100 parts by weight,
The method for producing a thermal transfer sheet according to claim 1, comprising 1 to 80 parts by weight of carnauba wax, 1 to 80 parts by weight of modified paraffin wax, and 0.5 to 40 parts by weight of alpha olefin-derived wax. 3) The method for producing a thermal transfer sheet according to claim 1, wherein the organic solvent is 1,4 dioxane.