JPH0158075B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a recording sheet for information recording equipment such as facsimile machines, printers, plotters, and copying machines.

Conventional configurations and their problems Conventional recording sheets for various information recording devices such as electrostatic recording paper, thermal recording paper, and thermal transfer paper have many minute thickness and density irregularities, so high-density recording is difficult. Even when heads were used, dropouts and uneven recording occurred, making it difficult to obtain high-quality characters and images.

Purpose of the Invention The purpose of the present invention is to provide a recording sheet that can be used in an information recording device to obtain high-quality character images with almost no dropouts or recording unevenness without special mechanical handling. shall be.

Structure of the Invention The present invention is a recording sheet having a recording surface with a GS smoothness of 300 seconds or more, and by improving the uniformity of the recording sheet, high quality images can be obtained.

Description of Examples Examples of the present invention will be described below, but first an outline of GS smoothness will be described.

In the conventional smoothness measurement method (JIS P8119 Beck smoothness measurement method), a sample is pressed between a glass plate and a rubber sheet, and a certain amount of air is passed through a small gap between the glass surface and the sample surface in the time it takes. The inventors improved this by sandwiching the sample between only glass plates (glass sandwich = G.
S), the smoothness is similarly expressed by air passage time (details will be described later). Therefore, while the conventional Beck smoothness evaluates only the condition of one side of the sheet, GS smoothness evaluates the overall uniformity such as thickness unevenness and density unevenness, including the condition of both sides of the sample. It is.

For example, the surface smoothness of a sample surface that is close to a mirror surface in its natural state and has a rough back surface (irregularities of several tens of μm) is several thousand seconds because the rubber sheet compensates for the unevenness of the back surface. On the other hand, with GS smoothness, the time is less than 100 seconds because it does not complement the back surface.

Such a difference in smoothness corresponds well to the recording state of recent high-density image recording. In other words, the platen surfaces of recording devices are becoming more hard due to miniaturization and higher precision, and conventional recording sheets with only high base smoothness are prone to dropouts and recording unevenness, making it difficult to produce high-quality characters and images. is becoming increasingly difficult to obtain.

The present invention will be described in detail by making various recording sheets using the above-described GS smoothness as a measure and describing the correspondence with image quality.

Methods and effects of recording methods using rigid recording heads such as thermal recording, thermal transfer recording, and electrostatic recording will be explained.

Example 1 A recording sheet was prepared by coating a base paper with a heat-sensitive coloring material, and an image was recorded using a line-type thermal head of 6 dots/mm and a platen roll of JIS rubber hardness of 80.

First, high-quality paper (manufactured by Jujo Paper Industries, Kinno, basis weight 66 g/m ² ) is prepared as the base paper. This GS smoothness is about 30
seconds, the Beck smoothness is approximately 70 seconds. On top of this, a heat-sensitive coloring layer of fine particle dispersed type consisting of 68% of bisphenol A, 2% of crystal violet lactone, and 30% of polyvinyl alcohol is applied in solid weight ratio.
It was coated and dried to a thickness of 5 μm. The base smoothness is approximately 100 seconds, and if recorded as is, drop-outs of approximately 40% will occur, resulting in image quality that is unsuitable for practical use.

The surface of this recording sheet was smoothed using a super calender roll, and several types of recording sheets with a maximum Beck smoothness of about 10,000 seconds were prepared and recorded in the same manner. As a result, dropout gradually decreased to 6% when the base smoothness was up to about 1,000 seconds, but even when the smoothness reached 10,000 seconds, dropout still occurred at about 2%. That is, unevenness remains on the back surface due to uneven density of the base paper.

On the other hand, on the back of these recording sheets, the average particle size
Dispersion containing approximately 20% polyvinyl alcohol as a binder in 0.1 μm fine clay powder (solid content 35%)
The back surface was smoothed by coating several to several tens of g/m ² of dry weight to increase the GS smoothness, and the same was recorded. As a result, even if the Beck smoothness is about 600 seconds, the GS
When the smoothness reached approximately 300 seconds, the dropout became less than 2%.

Therefore, we decided to use the record sheet for the number of points that we prepared.
If we look at the relationship between GS smoothness and dropout, we can see that dropout decreases significantly when the GS smoothness is around 300 seconds, and as the GS smoothness is smoothed to about 1,000 seconds, dropout is no longer observed and high-quality images are obtained. Obtained.

Example 2 For thermal transfer recording, wax type thermal transfer paper (manufactured by Fuji Kagaku Paper, capacitor paper type) was overlaid so that the coated surface was in contact with a separately prepared recording sheet of about 60 μm thick, which was then used as an image receiving paper. As in 1, insert it between the head and platen and record. Here, various types of image-receiving paper were adjusted by using a coloring material adsorbent such as clay, or by adjusting the GS smoothness according to the results of Example 1, and when the GS smoothness was adjusted to about 300 seconds, dropout occurred. was significantly reduced, and further smoothing to about 1,000 seconds yielded a complete image. However, even if only the Beck smoothness was increased to about 10,000 seconds, a dropout of several percent occurred.

On the other hand, as sublimation type transfer recording, on one side of a 6 μm thick polyimide film,
4-(4-N,N), a yellow-colored leuco dye
dibenzylaminophenyl)-pyridine (manufactured by Hodogaya Chemical Industries) and 30 parts of polysulfone as a binder.
Prepare a transfer sheet coated with g/m ² . In addition, the image receiving paper used as a recording sheet is clay paper (manufactured by Fuji Photo Film, Fuji Clay Paper 40) coated with activated clay (proton donor material) at approximately 10 g/m ² on high-quality paper.
g/m ² ). These two sheets are overlapped so that their coated surfaces are aligned and recorded in the same manner as in Example 1.

Here, since the GS smoothness of clay paper is approximately 80 seconds, the clay surface was supercalendered and the back surface was treated in the same manner as in Example 1.
When the smoothness was increased to about 300 seconds, an image with fewer dropouts was obtained. An almost perfect image was obtained with a GS smoothness of about 1,000 seconds. Even in this example of the sublimation method, it was not possible to obtain a high quality image simply by increasing the Beck smoothness.

As can be seen from Examples 1 and 2 above, the usefulness of recording sheets with increased GS smoothness is remarkable.

In addition, when the same effect was investigated by varying the hardness of the platen, it was found that relatively good images were obtained even with conventional recording sheets with increased Beck smoothness in the range of hardness up to about 60. However, when the recording sheet of the present invention is used as a platen, the hardness is
High quality images can be obtained on a range of materials from around 30 rubber to hard materials such as aluminum and brass.

In addition, although only examples using paper as the base material have been described as the recording sheet, the gist of the present invention includes a wide range of materials other than paper, such as plastics and cellulose, and the appropriate range of GS smoothness is limited regardless of the material. It is something to do.

Furthermore, examples of coloring materials are not limited to the examples, but include materials that change color or develop color in response to electrical signals from the recording head, and when using a thermal head, ordinary sublimable dyes and thermochromic materials may be used. It can also be applied to things that show.

The ability to provide excellent recording sheets in this way is due to the effect of the present invention, which succeeded in increasing the uniformity of the sheet, which had been overlooked in the past. It can be adjusted based on the new idea of degree.

Next, a method for measuring GS smoothness will be explained with reference to the drawings.

In Fig. 1, 1 is the sample, 2 is the gas through hole 3
4 is the plane of the gas-shielding rigid body, arrow A represents the main ingress direction and location of gas, and arrow B represents the direction and location of gas exit. This arrow B is an example of through-hole negative pressure, and pressure may be applied in the opposite direction. A glass surface with an outer diameter of 37.5 mm that has a circular hole of 11.4 mm in diameter as a gas through hole is used as a rigid plane, a paper is placed on this, and a mirror-finished stainless steel plate with a diameter of 37.5 mm is placed on top of it as a gas shielding surface. It was used as a rigid plane. While applying a load of 10 kg/cm ² to the pair of parallel planes and pressing the sample, open the gas through hole.
The pressure was reduced to 300 mmHg, and the passage time of 10 ml of air was measured. The measurement results are combined with the conventional BETSUTA method to
It is shown in Figure 3. The parameters in the figure represent the uniformity of the sample, and are obtained by dividing the smoothness of this method by the conventional base value.

First, Figure 2 shows data for about 20 types of coated paper.
To explain typical examples, 11 is 30-40g/ ^m2 glassine paper, 12 is 75g/m2 base paper, and 13 is base paper of 75g/ ^m2 .
36 g/m ² wax paper base paper, 14 is 64 g/m ² printing paper, and 15 is 37 g/m ² fruit bag base paper.

Figure 3 shows data for about 20 types of coated paper.To explain typical examples, 21 is a synthetic paper with a thickness of about 50 μm;
2 is 72-75g/ ^m2 fine coated paper, 23 is 160
g/m ² highly smooth clay paper, 24 is the back side of color photographic paper, and 25 is 290 g/m ² white paperboard.

As is clear from FIGS. 2 and 3, there is almost no correlation between the values obtained by this method and the Bekk value, and it is clear that the Bekk smoothness cannot be used to evaluate the sheet used between rigid bodies. Further, the higher the uniformity evaluated using this method, the less uneven the sheet is, and the synthetic paper shown at 21 in FIG. 3 is a very uniform sheet material. On the other hand, the glassine paper shown in Fig. 2 11 has become uniform in density due to calendering, but the original unevenness in papermaking has turned into uneven thickness, so the uniformity has decreased to 0.04. It has no meaning when used between rigid bodies.

When these 40 types of samples were used as packing materials, a proportional relationship was established between the measured values of this method and the packing function.

On the other hand, a heat-sensitive coloring layer having a composition of 68 bisphenol A, 2 parts crystal violet lactone, and 30 parts polyvinyl alcohol in a fixed weight ratio was coated on these samples to a thickness of about 5 μm to prepare thermal paper.
When this thermal paper was wound around a smooth aluminum drum and recorded with a line-type thermal head, the higher the smoothness of this method, the better the image was obtained.

Effects of the Invention As described above, according to the present invention, it is possible to provide a recording sheet capable of producing high-quality images free of dropouts and unevenness, which could not be obtained even by specifying the conventional base smoothness.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a device used to explain the method for measuring GS smoothness used in the present invention, Figure 2 is a diagram showing the smoothness of uncoated paper, and Figure 3 is a diagram showing the smoothness of various coated papers. FIG.

Claims (1)

[Claims] 1. A recording sheet having a recording surface with a GS smoothness of 300 seconds or more. 2. The recording sheet according to claim 1, wherein the recording surface has thermosensitive coloring properties. 3. The recording sheet according to claim 1, wherein the recording surface contains a colorant adsorbing material. 4. The recording sheet according to claim 1, wherein the recording surface has proton donor properties.