JPH05185759A - Image receiving paper for thermal transfer - Google Patents

Abstract

PURPOSE:To provide noncoat type image receiving paper for thermal transfer which has stiffness and is excellent in a writing characteristic by a method wherein in a monochromatic hot-melt thermal transfer printer, the image receiving paper for thermal transfer is excellent in dot reproducibility, free from cutting of a thin wire, and high in a collective printing quality level such as being high in transfer efficiency and high in printing density. CONSTITUTION:The title image receiving paper for thermal transfer is within a range of 40-400sec. Beck smoothness in accordance with JIS P 8119 and 0.65g/cm<3> in paper density. Further, by controlling the paper to 0.45-0.9W/(m.K) in thermal conductivity and a range of RP(25)=6-12mum in smoothness with a microtopograph, further a better printing aptitude is obtained. By additionally making paper so made as to be 0.45-0.60g/cm<3> in density, be 0.65-0.95g/cm<3> in density and 75-300sec. in Beck smoothness by calendering, a very excellent printing aptitude is obtained, and a blur in printing at a low impressed voltage part is not generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer image-receiving paper which is excellent in ink acceptability and dot reproducibility with respect to a fusion type thermal transfer printer, is free from fine line breaks, and has high printing density. It is about.

[0002]

2. Description of the Related Art In recent years, non-impact type output methods such as ink jet method and fusion type thermal transfer recording have become the mainstream as the OA of companies is progressing. Further, in the word processor for personal use, heat-sensitive recording using heat-sensitive paper or fusion type heat-transfer recording using heat-transfer image-receiving paper is the mainstream.

Especially for personal use and monochrome type printers, the running cost of the ink ribbon is low in addition to the printing quality, the maintenance is simple, and inexpensive non-coated type high-quality paper can also be used. Melt type thermal transfer printers have become popular. Recently, a handy type word processor that partially prints on various substrates has also been developed.

Conventionally, in order to obtain high printing quality, a highly smooth coat type thermal transfer image receiving paper has been used.

The reason for this is that non-uniform transfer of ink, faint printing, missing dots, etc. occur. Further, in order to satisfy the above conditions and reproduce a halftone, it is necessary to make a coat type and further devise various means.

Several proposals have already been made for a coat type thermal transfer image receiving paper. For example, JP-A-3-124
Japanese Patent Application Laid-Open No. 896 has a coating layer containing secondary agglomerated calcium carbonate, and Japanese Patent Application Laid-Open No. 59-16950 has a coating layer containing a water-soluble binder and a pigment. JP-A-63-872851 is provided with an adhesive layer, and JP-A-63-56486 is provided with a coating layer containing flaky barium sulfate.
JP-A-28693 proposes a thermal transfer image-receiving paper having a lipophilic coating layer containing an ethylene-vinyl chloride copolymer as a main component.

However, the coat type thermal transfer image receiving paper has a problem that the writing characteristics and the stiffness of the paper are inferior. Further, there is also a problem that transfer characteristics are inferior when printing is performed by a head having low heat generation efficiency.

[Problems to be Solved by the Invention]

A high-quality paper having a low smoothness has problems such as poor dot reproducibility, occurrence of fine line breaks, and low print density, and is not satisfactory as a thermal transfer image-receiving paper.

Conventionally, fine paper is crushed with a super calendar or the like to solve these problems, and high density and Beck smoothness of 4 are obtained.
The printing quality is improved by forming a highly smooth surface of 00 seconds or more. However, with this method, the stiffness of the paper is eliminated, and the transfer efficiency is reduced by the head having low thermal efficiency, and print fading occurs.

That is, according to the present invention, in a single-color fusion type thermal transfer printer, dot reproducibility is excellent, fine lines are not broken, transfer efficiency is high, and printing density is high. It is intended to provide a non-coat type thermal transfer image-receiving paper excellent in writing characteristics.

[Means for Solving the Problems]

As a result of repeated studies to solve the above-mentioned problems, the present inventors have found that when low-density paper is subjected to calendar processing,
It has been found that high printability, particularly good thermal transfer characteristics can be obtained by a method of finishing the paper to have a low density as much as possible without increasing the smoothness so much.

The present invention has a Bekk smoothness of 40 to 400 seconds according to JIS P8119 and a paper density of 0.6.
5 to 0.95 g / cm ³ . In addition, the thermal conductivity is 0.
45 to 0.9, smoothness by microtopography R
Even better printability is obtained by controlling P (25) = 6 to 12 microns. In addition, the paper made to have a density of 0.45 to 0.60 g / cm ³ was calendered to a density of 0.65 to 0.
By setting the Beck smoothness to 95 g / cm ³ and 75 to 300 seconds, very good printability can be obtained.

The following is a simple consideration of the process in fusion type thermal transfer recording. After the image receiving sheet, ink ribbon and printer head are in close contact,
In this process, the wax and pigment of the ribbon melted by heat from the printer head are transferred from the ribbon to the image receiving sheet and recorded.

The conditions required for the thermal transfer image receiving paper for recording by the above method will be described below.

First, the adhesion between the ink ribbon and the paper is good. In other words, if it is not smooth from a macro point of view, single dots may not be completely transferred or may not be transferred at all, resulting in the loss of some characters that are aggregates of dots, resulting in poor print quality. When the is printed, a thin line break occurs in which the line composed of dots is cut.

Secondly, the thermal conductivity is low. This is because if the heat generated in the printer head is not released from the part where the ink ribbon is pressed against the paper by the head, the wax and pigment on the ribbon will not all be transferred to the paper, resulting in a low print density. .. As a result, dot omission and thin line breakage are likely to occur.

However, the smoothness and the thermal conductivity, which are conditions generally required for the thermal transfer image-receiving paper, are in an opposite relationship. That is, a highly smooth surface has few voids and therefore does not contain the most adiabatic air layer.

Further, the smoothness required at the time of transfer requires macro smoothness and does not require micro smoothness in order to obtain close contact with the molten ink. Further, in order to obtain the anchor effect of the molten ink on the paper surface, the micro roughness shows a preferable effect.

The Beck's smoothness is greatly affected by microscopic smoothness, but since the microtopographic smoothness RP value is calculated from the contact rate with the prism surface, macro smoothness can be captured. (See Inamoto; Wakabayashi; Hosoi: Proceedings of the Printing Society of Japan, 17, No. 3, 78 (1978))

As a method for producing a smooth paper, there are a method of internally adding a filler, a method of increasing the linear pressure of a machine calendar, a super calendar and the like.

If 30% or more is internally added to obtain smoothness with a filler, there is a problem that the thermal conductivity increases and the heat insulating property decreases, and the stiffness of the paper disappears.

On the other hand, in the method of increasing the line pressure of the machine calender or super calender, increasing the nip line pressure increases the density and improves the smoothness. However, Beck's smoothness is greater than 300 seconds, and the topographic smoothness RP is
When (25) is smaller than 6 microns, the heat insulating property of the paper is deteriorated, so that the transfer rate at a low applied voltage is deteriorated to cause print fading, and there is a problem that the stiffness of the paper is eliminated.

As a method for producing low-density paper having low thermal conductivity, there are methods such as roughening beating of pulp, weakening linear pressure of wet press, soft calendar finishing, and weakening calender linear pressure. Conceivable.

In the method of roughening the beating of pulp and reducing the linear pressure of the wet press, the formation of hydrogen bonds is suppressed and the paper has a low density. To prevent the transfer rate from decreasing at a low applied voltage, the density of the thermal transfer image receiving paper should be 0.95 g /
It is necessary to be cm ³ or less, and if the thermal conductivity is 0.90 or less, a better effect can be obtained.

If the density of the paper is lower than 0.65 g / cm ³ , the heat of the head is accumulated and the ink transferred to the image receiving paper is not solidified and is transferred again to the ink ribbon, and the density is lowered. This tendency also appears when the thermal conductivity is smaller than 0.45.

By reducing the nip line pressure of the soft calender, super calender and machine calender, the paper becomes low in density.

As the density of the paper is reduced by this method, the smoothness of the paper decreases, but even if the Beck's smoothness is 40 seconds or more, dot dropout is slightly deteriorated when RP (25) = 12 microns. ..

In order to solve the above-mentioned problems, papermaking was performed at a density of 0.4 g / cm ³ or more and 0.6 g / cm ³ or less before smoothing treatment with a machine calender, a super calender or the like. By smoothing the paper, it is possible to obtain a paper having a low thermal conductivity and a high smoothness and excellent transferability. Printability of such a thermal transfer image-receiving paper is remarkably improved as compared with conventional high-quality paper.

In the present invention, in addition to inorganic pigments such as light calcium carbonate, heavy calcium carbonate, silica, titanium dioxide, aluminum hydroxide and aluminum oxide as a filler, urea resin, melamine resin, polyethylene and polystyrene as the main raw materials are used. A pigment may be added internally. It is also possible to mix and use several kinds of them at a ratio according to the purpose.

Plate-like pigments such as talc and kaolin do not adversely affect the print quality if the amount contained in the sheet is within 15% by weight.

The pulp used in the base paper of the present invention includes NBKP, LBKP, NBSP, LBSP, GP,
Examples include TMP and DIP. In use,
Several kinds of them are mixed and used at a ratio according to the purpose.

The thermal transfer image-receiving paper of the present invention may optionally contain a dye, a filler, a sizing agent, a fixing agent, a wet paper strength enhancer, a dry paper strength enhancer, etc., which are usually used in papermaking. is there. Further, in the surface treatment, it is possible to apply a surface sizing agent and a wet strength agent to the surface of the base paper with a size press and a gate roll coater, and it can be used by mixing with starch or by itself. It doesn't matter.

[0033]

[Function] In addition to being moderately smooth, especially in the macro sense, low-density paper and paper with low thermal conductivity have the necessary and sufficient characteristics as a monochrome type thermal transfer image-receiving paper. The reason for this is not clear, but it is thought to be roughly as follows.

Increasing the smoothness of the paper ensures the adhesion to the ink ribbon, and the ink transfer efficiency is increased to obtain a high density. However, the thermal conductivity is high, and the viscosity of the ink tends to increase during printing, making it difficult to fix the ink on the paper surface.

On the other hand, when the density of the paper is lowered, the smoothness of the paper surface is also lowered, but since the cushioning property of the paper is also increased, the adhesiveness to the ink ribbon is increased and the transfer efficiency is higher than that of high density paper with the same smoothness. Goes up. Further, it is possible to prevent the viscosity of the ink from increasing due to the decrease in thermal conductivity.

However, if the thermal conductivity is too low, the fluidity of the ink will be too high and the transfer efficiency of the ink will be reduced, so it is desirable to keep the thermal conductivity in an appropriate region in addition to the density and smoothness.

[0037]

EXAMPLES The present invention will be described in detail below with reference to examples. The present invention is not limited to the embodiments. All parts and percentages below are by weight. Further, the value indicating the smear amount is the weight after drying unless otherwise specified. Unless otherwise specified, the measurement and the printing test were carried out under the condition of 20 ° C. and 65% in an air-conditioned condition.

Example 1 Freeness 430 ml on PFI mill c. s. f. LBKP beaten up to 450 ml c. s. f. NBK beat up to
10 parts of light calcium carbonate (TP121, manufactured by Okutama Kogyo Co., Ltd.), alkyl ketene dimer sizing agent (Size Pine K903, manufactured by Arakawa Chemical Co., Ltd.) to 100 parts of pulp in which P was mixed in a weight ratio of 8: 2. Was added as an alkyl ketene dimer, and 0.8 part of cationized starch (Kate F, manufactured by Oji National Co., Ltd.) was added.
A handsheet of g / m ² was prepared. The handmade sheet was dehydrated under the condition that the linear pressure with a wet press was 5 kg / cm. The sheet was dried at 90 ° C. for 5 minutes. Then, the amount of the surface sizing agent (trade name: COLOPAR M150, manufactured by Seikou Kagaku Co., Ltd.) together with the oxidized starch (trade name: MS3800, manufactured by Nippon Food Processing Co., Ltd.) was applied to these sheets by a size press. 5 g / m ² and 0.0
It was smeared so as to be 5 g / m ² . Furthermore, the line pressure is 60k
Supercalendering was performed at g / cm to obtain a thermal transfer image receiving paper.

Example 2 A paper hand-made in the same manner as in Example 1 was used except that the linear pressure with a wet press was 5 kg / cm and the linear pressure with a super calender was 90 kg / cm. Samples prepared in the same manner as in Example 1 were obtained.

Example 3 A paper hand-made by the same method as in Example 1 was used except that the linear pressure with a wet press was 10 kg / cm and the linear pressure with a super calender was 60 kg / cm. Samples prepared in the same manner as in Example 1 were obtained.

Example 4 A paper hand-made in the same manner as in Example 1 except that the linear pressure with a wet press was 20 kg / cm and the linear pressure with a super calender was 90 kg / cm. Samples prepared in the same manner as in Example 1 were obtained.

Example 5 A paper hand-made by the same method as in Example 1 was used except that the linear pressure with a wet press was 20 kg / cm and the linear pressure with a super calender was 60 kg / cm. Samples prepared in the same manner as in Example 1 were obtained.

Example 6 A paper hand-made in the same manner as in Example 1 except that the linear pressure with a wet press was 20 kg / cm and the linear pressure with a super calender was 90 kg / cm. Samples prepared in the same manner as in Example 1 were obtained.

Example 7 A paper hand-made in the same manner as in Example 1 except that the amount of the filler added was 30 parts, and the linear pressure in a wet press was 20 kg.
/ Cm, line pressure on super calender is 30kg / cm
A sample prepared in the same manner as in Example 1 except for the above was obtained.

Comparative Example 1 A paper hand-made by the same method as in Example 1 was used except that the linear pressure with a wet press was 0 kg / cm and the linear pressure with a super calender was 90 kg / cm. Samples prepared in the same manner as in Example 1 were obtained.

Comparative Example 2 A paper hand-made in the same manner as in Example 1 was used except that the linear pressure with a wet press was 20 kg / cm and the linear pressure with a super calender was 120 kg / cm. Samples prepared in the same manner as in Example 1 were obtained.

Comparative Example 3 A paper hand-made in the same manner as in Example 1 was used except that the linear pressure with a wet press was 30 kg / cm and the linear pressure with a super calender was 150 kg / cm. Samples prepared in the same manner as in Example 1 were obtained.

The above results are summarized in Table 1.

[0049]

[Table 1]

Example 8 Except that the filler in Example 1 was replaced with talc (manufactured by Hyogo Talc Co.), the linear pressure with a wet press was 20 kg / cm, and the linear pressure with a super calender was 60 kg / cm. A sample prepared in the same manner as in Example 1 was obtained.

Example 9 The filler of Example 1 was replaced with talc (manufactured by Hyogo Talc Co.), the addition amount was 20 parts, and the linear pressure in a wet press was 2 parts.
0kg / cm, 60kg linear pressure on super calender
A sample prepared in the same manner as in Example 1 except that the value was / cm was obtained.

Comparative Example 4 The filler of Example 1 was replaced with talc (manufactured by Hyogo Talc Co.), the addition amount was 45 parts, and the linear pressure in the wet press was 2 parts.
0kg / cm, 60kg linear pressure on super calender
A sample prepared in the same manner as in Example 1 except that the value was / cm was obtained.

The above results are summarized in Table 2.

[0054]

[Table 2]

The density, thermal conductivity and smoothness of the thermal transfer image-receiving papers produced according to the above-mentioned Examples and Comparative Examples were measured. Further, as the measurement items after printing, print density, print unevenness and ruled line chipping were measured. The evaluation result of the printing was shown by an average value by visually judging the test pattern.

To evaluate the printability, Handy Writer-HW-7 by Casio, Word Processor Shoin WD310F by Sharp, Word Processor Bungou Mini 5 by NEC and Word Processor Rupo90H by Toshiba.
Was used as a printer.

1. The density was measured according to JIS P8118.

2. Smoothness was measured by a Beck tester according to JIS P8119.

3. The thermal conductivity was measured by a thermal conductivity meter Kemtherm QTM-D3 (manufactured by Kyoto Electronics Co., Ltd.).

4. The print density is the optical density (O
D) was measured by a Macbeth reflection densitometer model RD918. If the OD was 1.2 or more, there was no practical problem.

5. The smoothness RP was measured by Microtopography made by Toyo Seiki Seisakusho. Measuring pressure is 25kg /
m ² was performed.

6. Regarding the print unevenness and the print faint, it was visually evaluated whether or not the print faint occurred when a pattern having many solid print portions was printed. The case where the recording unevenness hardly occurs or the degree of concern is evaluated as ◯, the case where it is slightly conspicuous but not practically problematic is evaluated as Δ, and the practically problematic problem is evaluated as x.

7. As for the lack of ruled lines, the number of occurrence of thin line breaks due to missing dots etc. on the line where 10 ruled lines are printed is 3
Less than 20 places ○, less than 20 places △ and 2
Those having more than 0 points were evaluated as x.

[0064]

From the above examples, it can be seen that the thermal transfer image receiving paper of the present invention, that is, the paper which is moderately smooth and has a low density and a low thermal conductivity has excellent print quality as the thermal transfer image receiving paper. It was revealed.

Claims (3)

[Claims] 1. A thermal transfer image-receiving paper having a Beck's smoothness in the range of 40 seconds to 400 seconds measured according to JIS P8119 and having a paper density of 0.65 to 0.95 g /
An image-receiving paper for thermal transfer characterized by having a size of cm ³ . 2. The paper has a thermal conductivity of 0.45 to 0.90 W.
/ (MK) and smoothness by microtopography is 2
The image receiving paper for thermal transfer according to claim 1, wherein RP (25) = 6 to 12 microns at 5 Kg / m ² . 3. A density of 0.45 to 0.60 g / cm ³
The paper that has been made to have a density of 0.65 to 0.95 g / cm ³ and a Beck smoothness of 7 is calendered.
The image receiving paper for thermal transfer according to claim 1 or 2, wherein the receiving time is 5 to 300 seconds.