JP2681803B2 - Heat-sensitive stencil paper - Google Patents

Description

TECHNICAL FIELD The present invention relates to a heat-sensitive stencil sheet, and more particularly to a heat-sensitive stencil sheet having excellent printing characteristics.

(Prior Art) Various methods of stencil printing have been known, but in recent years, stencil paper made by adhering a heat-shrinkable film and porous thin paper with an adhesive is perforated by heat to print. Stencil printing is widespread.

As a method of perforating heat-sensitive stencil base paper by heat, a so-called flash is used in which the stencil base paper and the original are superposed and irradiated with infrared rays to adhere to the fibers of the porous thin paper to thermally shrink the film portion surrounded on four sides to perforate. There is known a perforation method or a so-called digital perforation method in which the film surface of the heat-sensitive stencil sheet is brought into contact with a heat-sensitive head so that the heat-sensitive head generates heat and the film portion in contact with the heat-sensitive head is perforated.

The digital perforation method is becoming the mainstream of the perforation method because of less soiling during the perforation compared to the flash perforation method.

In the digital perforation method, the heat generation amount of the thermal head is smaller than that in the flash perforation method, and therefore various proposals have been made to improve the perforation sensitivity with a low heat amount.

For example, Japanese Patent Application Laid-Open No. 61-53092 proposes a method of improving the perforation property of a film by using a porous thin paper having a porosity of 40% or more in a portion in contact with the film.

(Problems to be Solved by the Invention) However, as a printed matter after subjecting the perforated heat-sensitive stencil master to printing, it is a fact that a sufficiently satisfactory printed matter cannot be obtained only by improving the perforation property of the film. there were.

That is, even if the film portion in contact with the thermal head is sufficiently perforated so as to correspond to the heating dot portion of the thermal head, the dot connection of characters is poor, or the character is thick and the resolution is insufficient.

In addition, the uniformity of the image quality is poor, for example, the fiber shape (fiber grain) of the porous thin paper, which is the support in the solid portion, appears in the printed image, or the central portion of the solid portion becomes blank when printing multiple sheets. There was a point.

(Means for Solving the Problems) The inventors of the present invention have conducted extensive studies to solve the above-mentioned problems, and as a result, by adjusting the ink supply during printing using a specific porous thin paper, the resolution of characters can be improved. It has been found that a heat-sensitive stencil sheet having excellent printing characteristics and improved solidity uniformity and white spots can be obtained, and the present invention has been accomplished.

That is, the present invention is: 1) In a heat-sensitive stencil sheet obtained by adhering a heat-shrinkable film and a porous thin paper with an adhesive, the porous thin paper has a porosity of 12 to 25% and an average opening area of 2.5 × 10 ^3. ~ 5.5 × 10 ³ μ
A heat-sensitive stencil sheet characterized by using m ² and compression work of 0.10 to 0.16 gf · cm / cm ² .

2) The heat-sensitive stencil sheet according to item 1, wherein a porous thin paper having a Gurley stiffness of 3.0 mg or more is used.

3) The heat-sensitive stencil sheet according to item 1 or 2, wherein fibers having a melting point of more than 260 ° C are used as the fibers of the porous thin paper.

It is about.

The aperture of the porous thin paper in the present invention is a portion where light is seen to appear to form a hole, and contributes to ink supply during printing in consideration of a state in which the thin paper is compressed by a press roll during printing. It refers to the opening at the time of pressurization.

Open area ratio (%), average open area (× 10 ³ μm)
² ) and the area ratio (%) occupied by 6.0 × 10 ³ μm ² or more openings is made by Luzek IID image analyzer manufactured by Nireco Co., Ltd.)
Is measured. Porous thin paper (10 x 10 cm) with a thickness of 5 m
Place it on a transparent glass plate (10 x 10 cm) of m, and then put a transparent glass plate (3 x 3 cm) of 5 mm in thickness and scissors. Considering the press pressure at the time of printing, 1 x 1 cm in the center part. With holes 4.5
A weight of kg is placed on the glass plate (3 × 3 cm), and a weight of 500 gf / cm ² is applied to the porous thin paper, and 3 × 3 mm of the porous thin paper is passed through the holes of the weight.
The glass plate (3) is used to calculate the area of the aperture through which light is transmitted with the area of the
Change the position of the weight (× 3 cm) and perform the measurement at any 10 points, and adopt the value calculated by integrating the measurement data of 10 points.

The compression work (gf · cm / cm ² ) and compression recovery (%) in the present invention were obtained by stacking 10 sheets of porous thin paper and using a FB3 compression tester manufactured by Kato Tech Co., Ltd. to obtain a compression speed of 20 micron / sec.
At 0 gf / cm ² to 50 gf / cm ² and compress it,
The average value of the compression work amount and the compression recovery work amount when the compression is released from the compressed state at a speed of 20 micron / sec at any three points is adopted. Furthermore, the value calculated by compressive recovery work amount / compression work amount × 100 (%) as the compression recovery property (%) is adopted.

Examples of the heat-shrinkable film used in the present invention include polyethylene terephthalate, polyvinylidene fluoride, polyvinylidene chloride film and the like, but those having excellent low-temperature shrinkability are more preferably used from the viewpoint of piercing property, The thickness is preferably about 1.5 to 5 μm. 1.5μ
If it is less than m, it is difficult to handle, and if it exceeds 5 μm, an excessive amount of heat is required for perforation, and practical perforability cannot be obtained.

The porous thin paper used in the present invention has a porosity of 12-
25%, more preferably 14 to 20%, average open area 2.5 × 10 ³
~ 5.5 x 10 ³ μm ² , more preferably 2.5 x 10 ^{3 to} 4.5 x 10 ³ μ
m ^2, and more preferably ^{2.5 × 10 3 ~3.5 × 10 3} μm 2, the compression work amount 0.10~0.16gf · cm / cm ^2, more preferably 0.13~0.16gf
-It is not particularly limited as long as it is in the range of cm / cm ² .

If the porosity is less than 12%, it is not preferable because the ink supply amount is insufficient, the dot connection of characters is poor, the resolution is poor, and the uniformity of solid portions is poor. If the porosity exceeds 25%, the ink supply amount becomes excessive, the characters become thicker, the resolution is deteriorated, and the solid portion, which consumes a large amount of ink, becomes unclear, which is not preferable.

The average opening area is 2.5 × 10 ³ μm the ink supply amount and less than ² ties is insufficient character dot poor resolution can inferior, the average open area is more than 5.5 × 10 ³ μm ² Ink It is not preferable because the supply amount becomes excessive, the characters become thick and the resolution is deteriorated, and the solid printing portion, which consumes a large amount of ink, easily causes white spots. Further, since it is uneven 6.0 × 10 ³ μm ² or more apertures is the average opening area and increases in partially resolution thickening character even within the above range is reduced, 6.0 × 10 ³ μm ²
It is further preferable that the ratio of the above-mentioned openings is within 20% of the total opening area, more preferably within 15%.

Further, when the work of compression is less than 0.10 gf · cm / cm ^{2, the} work of compression recovery is small and it is difficult to return from the compressed state, so the volume change due to substantial compression (hereinafter referred to as the compressed volume). Is small, the amount of ink taken into the porous thin paper is small due to the compressed volume when the compressed state is restored after being compressed by the press roll at the time of printing. It is not preferable because the ink supply amount is insufficient and white spots occur. On the other hand, when the compression work exceeds 0.16 gfcm / cm ² , it is difficult to be compressed and the amount of change in volume due to compression is small, so when the ink is recovered from the compressed state after being compressed by the press roll during printing. The amount of ink taken into the porous thin paper is small,
A portion such as a solid portion that consumes a large amount of ink is not preferable because the ink supply amount is insufficient and white spots occur.

Examples of fibers constituting the porous thin paper of the present invention include Manila hemp, kozo, natural fibers such as mitsumata, or PET,
Synthetic fibers such as nylon and PPS (polyphenylene sulphite) may be mentioned. The type of fiber, average fiber diameter, beating degree and the like are appropriately selected and used alone or as a mixture within the physical properties of the porous thin paper. To be In the case of natural fiber, if the beating degree is low, both the opening rate and the average opening area are large, and if the beating degree is high, the opening rate and the average opening area are both small, but the beating degree is 20 to 30 ° SR ( JISP-8121) fiber and beating degree 20
Fibers of less than ° SR, preferably 14-16 ° SR
40-60% by weight: When used in combination with 60-40% by weight, the porosity is high,
Moreover, the average aperture area can be reduced, and the resolution is improved, which is more preferable.

In the case of the digital perforation method, since the thermal head contacts not only the film but also the thin paper when perforating with the thermal head, the Gurley stiffness (JIS L-1079-5-17E) of the porous thin paper is approximately 3.0 mg or more. It is more preferable to mix the fibers as described above to increase the strength of the porous thin paper because sticking is less likely to occur, and fibers having a melting point of more than 260 ° C. are more preferably used.

Further, in order to increase the adhesiveness between fibers, a fibrous binder may be mixed in a range that does not cause sticking and does not impair printing characteristics.

As a method for papermaking the porous thin paper used in the present invention using the above fibers, a wet papermaking method using an ordinary cylinder-shaped paper machine or the like may be used, and a paper-strengthening agent usually used at this time, A papermaking aid such as a dispersant may be used within a range that does not impair the printing characteristics.

Next, the film and the porous thin paper are laminated with an adhesive, and a sticking prevention layer is further provided on the film surface as required to obtain a heat-sensitive stencil sheet.

The adhesive is not particularly limited as long as it can bond the film to be used with the porous thin paper and is heat-dissipative, and examples thereof include vinyl acetate-based, acrylic-based, and polyester-based adhesives. As the above-mentioned sticking prevention layer, for example, a surface-active agent, a lubricant, a material having a releasing property such as silicone can be used.

(Effects of the Invention) As a porous thin paper used as a heat-sensitive stencil sheet, a porous thin paper having a porosity, an average open area and a compression work within a specific range. It was not enough to improve the perforability of the film itself by adjusting the ink supply by using the excellent resolution of characters, and the uniformity of solid areas and the printing characteristics with improved white spots. An excellent heat-sensitive stencil sheet is provided.

(Example) Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to these Examples.

The evaluation method in the examples is as follows.

1) Deformation of solid perforated portion after plate making was visually judged by the following ranking.

○ Not deformed △ Slightly deformed × Severely deformed 2) Resolution Visually determined connection of dots of characters and thickening according to the following criteria.

 ◎ Very good ○ Good △ Some dots are not connected. Or a little overweight.

 × Dot connection is bad. Or, the characters are thick and difficult to read.

3) Uniformity of solid part It was visually judged by the following ranking.

 ○ Good △ Slightly inferior × Poor 4) White spots in solid area Visually judged by the following ranking.

○ Good △ Somewhat bad × Example 1 Beating degree of Manila hemp having an average fiber diameter of 14 μm 60 weight parts of fibers beaten to 28 ° SR and Manila hemp having an average fiber diameter of 12 μm
Using a mixture of 40 parts by weight of fibers beaten to 15 ° SR by a wet paper making method with a round-net paper machine, the tsubo, opening ratio, average opening area, compression work amount and A porous thin paper having properties such as compression recovery was prepared.

Next, heat shrinkable PET film of 2.5 μm and polyester adhesive (KV-35 manufactured by Konishi Bond Co., Ltd.) 0.6 g /
Each was laminated via m ² (solid content).

Furthermore, 0.3 g / m ^{2 of a} silicon-based surfactant was applied to each surface of the laminated films to prepare a heat-sensitive stencil sheet.

The heat-sensitive stencil sheet obtained as described above was used as a manuscript using the Image Electrophotographic Society Test Chart No. 2 as a manuscript, and was made with a digital perforation type Gakken ODX-2020 plate making machine (manufactured by Gakken Co., Ltd.) to obtain a solid plate making part. After evaluating the deformation state, lithograph AP72
Printing was performed with a 00 printing machine (made by Riso Kagaku Kogyo Co., Ltd.) to evaluate the printing characteristics.

Table 2 shows the obtained results.

Example 2 Manila hemp having an average fiber diameter of 10 μm was beaten to a degree of beating of 30 ° SR 40 parts by weight of fiber and Manila hemp having an average fiber diameter of 14 μm
Using a mixture of 60 parts by weight of beaten fiber at 16 ° SR and a wet papermaking method with a round-net paper machine, the tsubo, porosity, average open area, compression work and A porous thin paper having properties such as compression recovery was prepared.

Next, a heat-sensitive stencil sheet was prepared in the same manner as in Example 1,
Plate making and printing were carried out in the same manner as in Example 1 to evaluate the plate making characteristics and the printing characteristics.

Table 2 shows the obtained results.

Example 3 Manila hemp having an average fiber diameter of 14 μm was beaten to a degree of beating of 28 ° SR. 80 parts by weight of fibers and Manila hemp having an average fiber diameter of 14 μm were beaten to be beaten.
Using a mixture of 20 parts by weight of fibers beaten at 15 ° SR and a wet papermaking method with a round-net paper machine, the weight per square meter, the open area ratio, the average open area, the compression work amount, and A porous thin paper having properties such as compression recovery was prepared.

Next, a heat-sensitive stencil sheet was prepared in the same manner as in Example 1,
Plate making and printing were carried out in the same manner as in Example 1 to evaluate the plate making characteristics and the printing characteristics.

Table 2 shows the obtained results.

Example 4 30 parts by weight of PET fibers having an average fiber diameter of 8 μm and an average fiber diameter of 14
Using a mixture of 20 parts by weight of fibers beaten to a degree of beating of 28 ° SR for Manila hemp of μm, wet-paper-making method using a round-net paper machine. A porous tissue paper having properties such as area, compression work and compression recovery was prepared.

Next, a heat-sensitive stencil sheet was prepared in the same manner as in Example 1,
Plate making and printing were carried out in the same manner as in Example 1 to evaluate the plate making characteristics and the printing characteristics.

Table 2 shows the obtained results.

Example 5 Manila hemp having an average fiber diameter of 12 μm was beaten to a degree of beating of 28 ° SR.
35 parts by weight of fibers beaten to 15 ° SR and an average fiber diameter of 8 μm
Using a mixture of 30 parts by weight of PPS fibers and a wet paper making method using a round-net paper machine, the weight per square meter, open area, average open area, compression work, compression recovery, etc. A porous thin paper with characteristics was produced.

Next, a heat-sensitive stencil sheet was prepared in the same manner as in Example 1,
Plate making and printing were carried out in the same manner as in Example 1 to evaluate the plate making characteristics and the printing characteristics.

Table 2 shows the obtained results.

Comparative Example 1 Manila hemp having an average fiber diameter of 14 μm was beaten to a degree of beating of 28 ° SR, and a fiber was formed by a wet papermaking method using a reticulated paper machine.
A porous thin paper having the properties shown in 1 such as tsubo, porosity, average open area, compression work and compression recovery was produced.

Next, a heat-sensitive stencil sheet was prepared in the same manner as in Example 1,
Plate making and printing were carried out in the same manner as in Example 1 to evaluate the plate making characteristics and the printing characteristics.

Table 2 shows the obtained results.

Comparative Example 2 Manila hemp with an average fiber diameter of 14 μm was beaten to 20 parts by weight of fibers beaten to 21 ° SR and Manila hemp with an average fiber diameter of 14 μm was beaten.
Using a mixture of 80 parts by weight of fibers beaten to 15 ° SR and a wet papermaking method with a round-net paper machine, the weight per square meter, the open area ratio, the average open area, and the compression work amount shown in Table 1 A porous thin paper having properties such as compression recovery was prepared.

Next, a heat-sensitive stencil sheet was prepared in the same manner as in Example 1,
Plate making and printing were carried out in the same manner as in Example 1 to evaluate the plate making characteristics and the printing characteristics.

Table 2 shows the obtained results.

Comparative Example 3 Using a PET fiber having an average fiber diameter of 9 μm and a wet papermaking method with a round-net paper machine, the weight per square meter, the open area ratio, the average open area, the compression work amount and the compression recovery property shown in Table 1 were measured. A porous thin paper with characteristics was produced.

Next, a heat-sensitive stencil sheet was prepared in the same manner as in Example 1,
Plate making and printing were carried out in the same manner as in Example 1 to evaluate the plate making characteristics and the printing characteristics.

Table 2 shows the obtained results.

Comparative Example 4 50 parts by weight of PET fiber having an average fiber diameter of 9 μm and an average fiber diameter of 10
Using a mixture of 50 parts by weight of fibers that have been beaten to a degree of beating of 28 ° SR for Manila hemp, and using a wet papermaking method with a reticulated paper machine, the tsubo, porosity, and average porosity shown in Table 1 A porous tissue paper having properties such as area, compression work and compression recovery was prepared.

Next, a heat-sensitive stencil sheet was prepared in the same manner as in Example 1,
Plate making and printing were carried out in the same manner as in Example 1 to evaluate the plate making characteristics and the printing characteristics.

Table 2 shows the obtained results.

Claims (3)

(57) [Claims] 1. A heat-sensitive stencil sheet obtained by adhering a heat-shrinkable film and a porous thin paper with an adhesive, wherein the porous thin paper has a porosity of 12 to 25% and an average open area of 2.5 × 10 ^{3 to} 5.5.
A heat-sensitive stencil sheet characterized by using x10 ³ µm ² and a compression work of 0.10 to 0.16 gf · cm / cm ² . 2. The heat-sensitive stencil sheet according to claim 1, wherein a porous thin paper having a Gurley rigidity of 3.0 mg or more is used. 3. A fiber according to claim 1, wherein a fiber having a melting point of more than 260 ° C. is used as the fiber of the porous thin paper.
The heat-sensitive stencil sheet according to item 2 or 3.