JPS6013595A - Thermal recording material and base therefor - Google Patents

Abstract

PURPOSE:To provide a thermal recording material having a high heat sensitivity and enhanced in color forming efficiency in high-speed printing, wherein a thermal layer is provided on a glazed side of a base produced by a Fourdinier paper machine, glazed on one side thereof and having a specified paper layer density. CONSTITUTION:The thermal layer comprising a leuco dye, a color developer and, if required, a filler and a heat-fusible substance is provided on the glazed surface of a base consisting of a paper having a paper layer density of not higher than 0.75g/cm<2>, preferably, not higher than 0.70-0.74g/cm<2>, which is produced by a Fourdrinier paper machine and subjected to single-side glazing drying by a mirror surface drier.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a heat-sensitive recording material and its support.

[Prior art]

Conventionally, various heat-sensitive recording materials are known in which paper is used as a support and a heat-sensitive layer is provided on the surface of the paper.
Since it is a secondary color development and does not require development, it has advantages such as being maintenance-free, having little noise, and being easy to reduce in size and weight, and the demand for it is increasing year by year. However, in the case of such a thermal recording system, since the recording energy is heat, there is a limit to the response speed of the recording element, and there is a problem that the recording speed is still insufficient. Particularly in the fields of facsimiles and printers, high-speed recording is required, and there is a strong desire to improve the recording speed.

Conventionally, in order to increase the recording speed, it is of course necessary to improve the thermal head section of the recording device, but at the same time, it is also important to increase the thermal sensitivity of the heat-sensitive recording material and improve the printing color development speed. be. A common method for increasing the thermal sensitivity of heat-sensitive recording materials is to perform pressure surface treatment using an off-machine calender to improve surface smoothness. However, in this case, calender treatment If the pressure is increased above a certain value, the reaction between the dye and the color developer will proceed, causing background fogging, and there is a limit to the improvement of surface smoothness. The surface obtained by calendering is
There is also the disadvantage that the gloss becomes stronger and the stitching becomes worse. Furthermore, in order to increase thermal sensitivity, it has been proposed to provide an undercoat layer on the surface of the support and a heat-sensitive layer on top of the undercoat layer. However, in this case,
There is a problem in that it takes time and money to apply the undercoat layer, resulting in high costs.

〔the purpose〕

An object of the present invention is to solve the above-mentioned problems found in the prior art and to provide a heat-sensitive recording material that has significantly increased thermal sensitivity and improved coloring efficiency in high-speed printing.

〔composition〕

According to the present invention, a paper layer density of 0.75 g/
A heat-sensitive recording material is provided, characterized in that paper of cm3 or less is used as a support, and a heat-sensitive layer is provided on the glossy surface of the paper to improve printing color development speed.In the present invention, as a heat-sensitive recording material support, , is characterized by the use of a special paper, but it has not been known to date that the thermal sensitivity can be increased by specifying the structure of such a support. The present inventor was conducting various research on the relationship between the support and the thermal sensitivity regarding thermal recording materials, and discovered that the paper layer density was It has been found that a heat-sensitive recording material formed using paper as a support with a particle diameter of 0.75 g/cm3 or less has high thermal sensitivity and extremely high coloring efficiency in high-speed recording. The support that has been commonly used in the past is what is called "general double-quality paper," and foam paper or printing paper is used as the support, but such high-quality paper is The paper is made using a paper machine, and then dried evenly on both sides using a multi-tube dryer to ensure that there is as little difference between the front and back sides as possible. According to the research conducted by the present inventors, it has been found that the above-mentioned special paper provides a heat-sensitive recording material with superior heat sensitivity as a support compared to such conventionally used high-quality papers. The support used in the present invention has a surface (glossy surface) with Bekk smoothness (JI)
SP8119) provides a heat-sensitive recording material with increased heat sensitivity, even at the same level as conventional high-quality paper. Further, in the case of the present invention, the paper layer density is specified to be 0.75 g/am' or less. In the case of conventional high-quality paper, the paper layer density is 0.77
~0.83 g/cI113, but 1 In the case of the support of the present invention, in order to obtain a product with increased heat sensitivity, its paper layer density is below 0.75, preferably between 0.70 and 0.74 g/cI.
It is necessary to keep it within the range of cm3. Note that the paper layer density in this specification refers to the density expressed by the linear equation.

The support used in the present invention consists of a base paper produced by making paper using a Fourdrinier paper machine and drying the resulting paper with a mirror dryer to give it a glossy surface. If so, only one side (the felt side) should be in contact with the dryer surface. These drying conditions are not particularly restricted.

All you have to do is bring the damp paper into strong contact with the dryer surface. Furthermore, the paper layer density of the resulting base paper can be adjusted to a desired range by adjusting various conditions during papermaking, such as the type of valve, degree of beating, papermaking speed, wire mesh, etc.

The heat-sensitive recording material of the present invention is one in which a heat-sensitive layer is provided on the glossy surface of the support described above, and in this case, various conventionally known heat-sensitive layers can be used. In addition to a heat-sensitive layer consisting of a single or multiple coating layer containing a coloring agent and further containing a filler and a heat-fusible substance as necessary, a heat-sensitive layer containing a diazo compound and its coupler, and a filler and a heat-fusible substance as necessary. Examples include a heat-sensitive coloring layer consisting of one or more coating layers containing a fusible substance. Further, the support of the present invention is a support for a thermal transfer recording material comprising a transfer sheet containing a leuco dye and a transfer sheet containing a color developer, a support for a thermal transfer sheet having a meltable ink layer, etc. It can also be used as

〔effect〕

The heat-sensitive recording material formed using the special support according to the present invention can efficiently absorb energy from the thermal head into the heat-sensitive recording layer, exhibiting enhanced thermal sensitivity,
In particular, the printing color development speed in high-speed recording can be improved.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 Pulp compounded by beating to 450 cc of freeness (C5F, freeness measured by Canadian Standard Type Testing Machine, the same applies hereinafter) and containing 40% by weight of 9LDKP (broad leaf complementary kraft pulp) and 60% by weight of NBKP (softwood 0West kraft pulp) rosin size 1.2% by weight, sulfate band 2 per pulp
．． A paper stock was obtained by adding 5% by weight and 1.0% by weight of melamine resin. This paper stock was made into paper using a Fourdrinier paper machine, and then dried on one side using a mirror dryer to obtain the support of Example 1. Note that the papermaking speed in this case was 150 m/min, and the drying temperature was 140°C.

Example 2 To a pulp blend of 80% by weight of bleached GP (ground pulp) and 20% by weight of NBKP beaten to a freeness (C5F) of 500cc, rosin size of 1.2% by weight per pulp,
A paper stock was obtained by adding 2.5% by weight of aluminum sulfate. This paper stock was made into paper using a Fourdrinier paper machine, and then dried on one side using a mirror dryer to obtain the support of Example 2.

Note that the papermaking speed in this case was 150 m/min, and the drying temperature was 140°C.

Comparative Example 1 A support of Comparative Example 1 was obtained in the same manner as in Example 1, except that a multi-barrel dryer (30 barrels) was used instead of the mirror dryer, and the wet paper was dried from both sides. Note that the papermaking speed was 3001 Il/min, and the drying temperature was 130° C. as the average temperature of each dryer.

Comparative Example 2 A support of Comparative Example 2 was obtained in the same manner as in Example 2, except that a multi-barrel dryer was used instead of the mirror dryer. Note that the paper making speed and drying temperature are the same as in Comparative Example 1.

Comparative Example 3 A support of Comparative Example 3 was obtained, which was made of a commercially available high-quality printing paper made using a Fourdrinier multi-tube dryer paper machine.

Comparative Example 4 In Example 2, the paper making conditions were changed and the paper layer density was 0.8.
A support of Comparative Example 4 of 2 g/am3 was obtained.

Next, the physical properties of each of the supports described above are shown in Tables 1 to 1.

Table-1 Example 3 The following solutions A and B were prepared.

Solution A 3-N-Methyl-N-cyclohexylamino-6-methyl-7-anilinofluorane 15-fold 10% polyvinyl alcohol aqueous solution]-2n Water 73n N-liquid calcium carbonate 10 parts by weight Sodium polyacrylate 0 .05 IIP-benzyl oxybenzoate 101! 10% polyvinyl alcohol aqueous solution 15! I water 64.95 // After dispersing liquid A and liquid B for 24 hours using a Paul Milla 1 lighter, mix and stir liquid ^ and liquid B at a weight ratio of 1:4 to obtain a heat-sensitive coating liquid. This coating solution was applied to the surface of each of the above-mentioned supports using an air knife coater at a dry coating weight of 7 g/In2, dried to the extent that no coloring occurred, and further checked for Bekk smoothness using a super calender. The heat-sensitive recording papers A to F were obtained by surface treatment such that the time was 500 to 600 seconds.

These thermal recording papers were printed using a facsimile tester (manufactured by Matsushita Electronic Components Co., Ltd.) with a head voltage of 13 V, platen suppression of 1.0 g, and pulse width varying from 1.0 ms to 2.2 ms. The coloring efficiency of the thermal recording paper was determined based on the density. The results are shown in Table-2. Note that the print density and background density were measured using a Macbeth densitometer.

As is clear from the results shown in Table 2 above, the thermal recording paper formed using the special support according to the present invention has the following properties:
Even with the same pulse width, the printing density is high and the single color development efficiency is excellent.

Patent applicant Rico Co., Ltd. Representative Patent Attorney Toshiaki Ikeura

Claims (2)

[Claims] (1) A heat-sensitive recording material support made of paper with a paper waste density of 0.75 g/cm3 or less, which is made using a fourdrinier paper machine and dried to make one side glossy using a mirror dryer. (2) Using paper with a paper waste density of 0.75 g/cm3 or less that has been made using a Fourdrinier paper machine and polished and dried on one side using a mirror dryer as a support, a heat-sensitive layer is provided on the glossy surface, and color printing is achieved. A heat-sensitive recording material characterized by improved speed.