JPS61118294A - Transfer paper for transfer type thermal recording - Google Patents

Abstract

PURPOSE:To raise the guality of printing by including an ionomer resin in an amount of 50% or more of a binder used in an ink receiving layer in the ink receiving layer composed primarily of a binder resin, a wax, and a pigment as main components, provided on the ink receiving face of a transfer paper. CONSTITUTION:An ink sheet 3 having a heat-meltable ink layer 2 and a transfer paper 5 are laminated on the surface of an ink sheet base material 1. An image signal from a thermal head 6 is given in the form of heat to them to transfer hot-melt ink to the paper 5 having an ink receiving layer 4 on the transfer paper base material 7. The layer 4 consisting of a mixture of a wax and an ionomer resin exhibits its good acceptability for heat-meltable ink over all energy region from small energy to great energy. The ionomer resin, which is ones combined with metal ions obtained from copolymerization of ethylene and an unsaturated carboxylic acid, has good miscibility with pigment due to loosening of ion bonds when heated and exhibits good compatibility with other resins and waxes.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a transfer paper for transfer-type thermal recording, and particularly to a melt-transfer type transfer paper that expresses gradation by modulating the area of dots.

BACKGROUND ART It is known that when a conventionally known coated paper is used as a receiving paper for transfer-type thermal recording, the print becomes clearer and the quality thereof is improved.

However, when trying to express halftones by dot area modulation, these ordinary coated papers lack the adhesive strength between the molten ink and the ink receiving surface of the transfer paper, so it is difficult to express fine dots in full color. Accurate transcription cannot be performed,
Color reproducibility is impaired.

On the other hand, there is a method in which a coating material application area is provided on the ink sheet to make it easier to transfer the surface condition of the transfer paper, and this coating material is coated on the surface of the transfer paper using heat from a thermal head prior to printing. There are some, but
This method requires one extra step of surface coating, and the ink sheet also requires an extra coating material application area.
In terms of printing speed (°C) and running costs,
Also, considering the lifespan of the thermal head, it is not an IFI measure.

Separately, if you use a transfer paper coated with wax, which is the main component of the molten ink layer or similar to it, as an ink-receiving layer, the ink adhesion will be large and it will be possible to accurately form minute dots with a small amount of energy. Transfer becomes possible, but since the ink receiving layer melts during printing,
There are drawbacks such as the dots spreading out or the center of the dots falling out due to large amounts of energy.

Another drawback is that the transferred image changes depending on the timing and angle of peeling off the ink sheet and transfer paper after printing, and it lacks universality and stability. Furthermore, this type of transfer paper is not writable with a pencil or ballpoint pen.

Purpose This invention aims to solve the above-mentioned problems of the prior art and provide a method for obtaining a painterly color hard copy including halftones.

Toyoichi" [The structure of the present invention to achieve the above object is to bring an ink sheet coated with heat-melting ink onto one side of the base material into contact with the paper to be transferred, and then apply pressure from the opposite side of the base material to the ink coated side. In the transfer paper used in a recording method in which a thermal head applies a thermal signal to transfer melted ink to the transfer paper for recording, an ink-receiving layer formed on the ink-receiving surface of the transfer paper is coated with a binder. The transfer paper for transfer-type thermal recording is mainly composed of resin, wax, and pigment, and the binder contains an ionomer resin in an amount of 50% or more of the binder.

As shown in FIG. 1, in the transfer-type thermal recording, an ink sheet 3 having a heat-melting ink layer 2 on the surface of an ink sheet base material 1 and a transfer paper 5 are superimposed, and thermal printing is performed from the back side of the ink sheet 3. This is a method in which a hard copy is obtained by applying an image signal in the form of heat using a head 6 and transferring thermally molten ink to a transfer paper 5 having an ink receiving WJ 4 on a transfer paper base 1. This method has been particularly developed and popularized in recent years. is remarkable.

Transfer-type thermal recording does not require any special processing for image formation on the transfer paper; it only needs to be smooth and sheet-like with good ink adhesion; no processing is required for general document printing. Plain vapor and general-purpose coated paper are used. Also, even if it is a full color printer,
General-purpose coated paper is used in a system that attempts to express halftones by combining N10FF binary modulation and the teaser method.

However, when trying to obtain images of higher quality, it is clear that so-called area modulation, which changes the size of pixels, is superior.

Conventionally, area modulation has been considered impossible in transfer type thermal recording, particularly in the melt transfer method which is the field of the present invention. This is because in melt transfer, it has been thought that only 0N10FF modulation is possible because the relationship between applied energy and change in transferred image area is too rapid. In fact, even if an attempt is made to modulate the area by modulating the applied energy using conventional general-purpose coated paper as the transfer paper, it is difficult to accurately transfer minute dots due to insufficient adhesion of the ink to the transfer paper, and the ink When the sheet and transfer paper are peeled off, the periphery of the transfer dots may be turned up or chipped, making it impossible to accurately transfer dots with intermediate areas. In an attempt to solve this problem, wax, which is the main component of molten ink, is used as the ink-receiving layer of the transfer paper, and strong adhesion is generated due to eutectic fusion between the ink and the ink-receiving layer. By applying a small amount of energy while matching the physical properties, it is possible to accurately represent minute dots, which was impossible with conventional art paper. However, if the applied energy is increased, the ink-receiving layer is thermally melted or thermally deformed, resulting in a disadvantage that the size and shape of the transferred dots become disordered.

Needless to say, it is possible to improve this drawback to some extent by using a wax with a high melting point in the ink-receiving layer, but waxes with a high melting point have the disadvantage that fine dots cannot be transferred well when energy is applied. .

In order to accurately transfer minute dots, it is necessary to use a wax with a sharp melting point of 100°C or less and quickly turn into a liquid with low viscosity when melted. There is significant disturbance in the transferred dots.

This inventor researched the relationship between the properties of the molten ink and the surface of the transfer paper, and by improving the surface properties of the ink-receiving surface of the transfer paper even in the case of melt transfer, he succeeded in using a general thermal We have found that it is possible to modulate the dot area by modulating the applied energy even when using a synthetic ink sheet.

,: Sun9chi・'7'' No. 8A (;t/v
- It has been discovered that an ink-receptive layer made of a resin-free mixture has good heat-melt ink receptivity over the entire applied energy range from low energy to high energy, and by making improvements thereto, the present invention has been achieved. It was. The transfer paper according to the present invention is not concerned with the thermal properties of the heat-melting ink, but as long as it has wax as its main component, it is versatile because it exhibits its performance, and it also has surface mechanical strength. It is large, and it is possible to write down notes using a pencil or ballpoint pen. Furthermore, it has the advantage that it can be mass-produced at low cost because there are very few restrictions on industrial manufacturing methods due to the properties of the material.

The wax referred to in this invention refers to an organic substance that is solid or semi-solid at room temperature and capable of forming a continuous film when in the solid state, and that exhibits a low melt viscosity when melted at a temperature of 100° C. or lower. Specifically, animal waxes such as beeswax and spermaceti, vegetable waxes such as candelilla wax, rice wax, and carnauba wax, mineral waxes such as montan wax and osichelite, paraffin wax, microcrystalline wax, tsukus, etc. petroleum waxes, modified waxes that are derivatives of various other waxes,
Examples include hydrogenated waxes such as castor wax, various long sheath fatty acids, their salts, and derivatives.

In practicing this invention, wax is necessary as a component to strengthen the adhesion of the ink.

The optimum waxes are used alone or as a mixture of 281 or more waxes, with reference to melting point, heat capacity, dispersibility, compatibility with other components, etc.

When using wax, it is possible to dissolve or disperse it in a polar organic solvent and mix it with the ionomer resin, but from the standpoint of safety and cost, the ionomer is generally dispersed in water in the form of a so-called wax emulsion. It is preferable to use it in combination with an aqueous emulsion of resin.

The ionomer resin referred to in this invention is a resin made by copolymerizing ethylene and unsaturated carboxylic acid and chemically bonding metal ions to this, and can be used as an emulsion using water as a dispersion medium. Furthermore, solid resins are those that melt with heat and become liquid. Ionomer! Mrf
R has toughness due to the network structure of ionic bonds when cold,
When heated, these ionic bonds are loosened, making it highly miscible with pigments and exhibiting good compatibility with other resins and waxes.

It is also effective to blend components other than the ionomer resin as the binder resin, and natural and synthetic resins and their crosslinking agents are suitably blended for the purpose of imparting water resistance, heat resistance, hydrophilicity, etc.

Any pigment that can be used in this invention can be used as long as it is a pigment used in normal paper processing, but it is desirable that the transfer paper and ink receiving surface of transfer type thermal recording be white, so whiteness and opacity should be high. Something is desirable. Specifically, in addition to inorganic pigments such as titanium oxide, zinc oxide, calcium carbonate, silicon oxide, barium sulfate, aluminum hydroxide, kaolin, and clay, so-called 81 pigments, which are fine powders of organic polymer compounds, can also be used. . The use of pigments can remove surface irregularities, especially dents, and has the effect of preventing blocking.

The desirable ratio of each component is that the pigment should be in the range of 1/4 to 5/1 of the total weight of the binder resin and wax; if it is less than this, it will not be possible to cover the dents on the surface, or , there is no blocking prevention effect. If the amount is more than this, the adhesion of the ink will be insufficient and proper transfer will not be possible.

The ratio of binder resin and wax is 1/4 to 5/1 by weight.
If the wax ratio is less than this range, the adhesion of the ink will be insufficient, and if it is higher than this range, the disadvantage that the ink-receiving layer itself will melt becomes too large. In either case, correct transfer will not be possible. Components other than the ionomer resin in the binder resin must account for 50% or less of the binder resin; if it exceeds this amount, the ink may lack adhesion or the ink receiving layer may lack mechanical strength. Then, it no longer has sufficient performance as a transfer paper.

Note that these ratios are all 11 m ratios when dry.

The ink-receiving layer was coated by heating and melt-mixing the ink-receiving layer constituent composition without a solvent in addition to conventional coating methods such as a blade coater, roll coater, bar coater, air knife coater, spray coater, gravure, and flexography. It is also possible to top-knead and hot-melt coat.

The amount of coating is 2 when dry! A coating amount of J/rat to 20 g/l112 is desirable, but it is possible to increase the amount to about 30 (1 part m2). If it is more than that, cracking or peeling will occur, which is undesirable. The presence of a smooth, oil-resistant, and water-resistant subbing layer makes it easier to coat the ink-receiving layer, and helps maintain the surface smoothness, ink receptivity, and ink adhesion of the ink-receiving layer. It is very effective. Also, providing an anti-curl layer on the opposite side of the ink-receiving layer is also effective in keeping the ink sheet and transfer paper in flat and close contact during handling and printing.

Hereinafter, the present invention will be specifically explained with reference to Examples.

Note that all ff1 (parts) of each component described in the actual tM examples are parts by weight.

Example 1 Basis weight 45! The following composition was applied to II/l 2 high-quality paper so that the adhesion amount was 12 g/l 112 on the front surface and 5 g/l 12 on the back surface when dry.After drying, the surface and back surfaces were treated with a super calender to improve the Bekk smoothness of the front and back surfaces. 1200 seconds and 3 respectively
A base paper for transfer paper having a temperature of 0.00 seconds was obtained.

Kaolin clay (Ultra White 90, manufactured by Engelhard) Solid content 5
0% aqueous dispersion 40 parts PVA (PVA-117, manufactured by Kuraray) Solid content 10% aqueous solution 100 parts S, BR latex (Dow Latex DL636, manufactured by Asahi Dow) Solid content 48% 10.4 parts On the surface of this base paper When drying a composition consisting of the following composition,
(Coat to a coating weight of 1/+12, after drying, super calender treatment to achieve Beck surface smoothness of 20,000
Transfer paper 1 having a second Q ink-receiving layer was prepared.

Wax emulsion (Cellosol #686, manufactured by Middle East Yushi) Solid content: 50% 20 parts Ionomer resin (Chemivar 3-100 manufactured by Mitsui Toatsu) Solid content: 27% 37 parts Titanium oxide (Tybake W-10, manufactured by 6 Hara Sangyo) Solid content 20% paste 10 parts zinc oxide (
No. 3 Zinc White (manufactured by Sakai Chemical Co., Ltd.) 20% solids paste 40 parts Example 2 Transfer paper 2 was prepared in the same manner as transfer paper 1 except that the composition for forming the ink-receiving layer was as follows. did.

The Beck surface smoothness of this product was 6800 seconds.

Wax emulsion (Cellosol #524, manufactured by Middle East Oil) Solid content: 30% 33 parts Ionomer resin (Cobolene Latex L 5ooo, manufactured by Asahi Dow) Solid content: 39% 51 parts Titanium oxide (Tybake W-10, manufactured by 6 Hara Sangyo) Solid 20% paste 90 parts Calcium carbonate (Hakuenka PX, Shiraishi Calcium fJ) Solid content 40%
Paste 105 parts Example 3 The composition for forming the ink-receiving layer of the transfer paper 2 was
A receiving paper 3 having a Beck surface smoothness of 5200 seconds was prepared by directly coating, drying, and super calendering on a 5 g/m' high-quality paper to a coating weight of 28 g/1112 when dried.

Example 4 Transfer paper 4 was prepared in the same manner as transfer paper 1 except that the composition for forming the ink receiving layer was as follows. The Beck surface smoothness of this item is 48
It was 00 seconds.

Wax emulsion (Cellosol #686, manufactured by Middle East Yushi) Solid content 50% 20 parts Ionomer resin (Corpolene Radex L 4000, manufactured by Asahi Dow) Solid content 39% 103 parts Silicon dioxide (Aerosil 200, manufactured by Nippon Aerosil)
10% solids dispersion 500 parts Carnauba wax 30 parts Paraffin wax (melting point 65°C) 30 parts Liquid paraffin
10 parts ethylene, vinyl acetate copolymer (trade name Evaflex #210, manufactured by Mitsui Polychemicals) 15 parts carbon black for pigments 15 parts composition to 12 parts
A hot-melt ink was prepared by cross-dispersing it for 3 hours with a thermal attritor at 0°C, and then applied to a 6-μm-thick biaxially stretched polyester film to a thickness of 3.5 μIIc using a hot-melt method. I created a sheet.

This ink sheet and transfer paper are brought into close contact, and the pressure of the rubber platen and thermal head is 0.5k (+/el).
In step 12, 100 dots were printed each by changing the energy applied to the thermal head. The ink sheet and transfer paper were peeled off 2 seconds after printing.

Comparative example 1 has a basis weight of 130 (1/w2, surface smoothness of 12
000 seconds art paper.

As Comparative Example 2, a mixture of 50 parts of carnauba wax and 50 parts of paraffin wax (melting point 65°C) was applied to a high-quality paper of Tsubofit 650/I11' using hot melt coating to give a ratio of 20(]/i2). The results are shown in Table 1 below.

Table 1 Shape of transfer dots In Table 1, the phenomenon in which the periphery of the dot becomes loose is the phenomenon shown in Figure 2, and the phenomenon in which the center of the dot slips out is the phenomenon shown in Figure 3.
The phenomenon shown in the figure and the spread of dots are the phenomena shown in FIG. 4, respectively.

When such a phenomenon occurs, the relationship between applied energy and dot size, that is, image density, is disturbed, making it impossible to express correct gradation.

Effects As explained above, according to the present invention, it is possible to always transfer dots with an area corresponding to the magnitude of the energy, regardless of whether the energy applied to the thermal head is small or large. Therefore, dot area modulation due to energy modulation can be performed with high ir! It can be implemented with X.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the transfer-type thermal recording method using the transfer paper of the present invention, Fig. 2 is an enlarged view showing an example of transfer dots with jagged edges, and Fig. 3 is a diagram showing an example of transfer dots with jagged edges. FIG. 4 is an enlarged view showing an example of a spread transfer dot with a handling number tap in the center. DESCRIPTION OF SYMBOLS 1... Ink sheet base material, 2... Heat-melt ink layer, 3... Ink sheet.

Claims (1)

[Claims] An ink sheet coated with heat-melting ink on one side of the base material is brought into contact with the paper to be transferred, and a thermal signal is applied from the opposite side of the base material to the ink-coated surface to transfer the molten ink to the paper to be transferred. In the transfer paper used in the recording method for recording, the ink-receiving layer provided on the ink-receiving surface of the transfer paper is mainly composed of a binder resin, wax, and pigment, and the binder is 5. Ionomer resin as a binder
A transfer paper for transfer type thermal recording characterized by containing 0% or more.