JPH0230593A - Thermosensitive stencil paper - Google Patents

Abstract

PURPOSE:To obtain printed matter which is excellent in resolution of letters and characters and of which uniformity, reverse printing property, etc., of a solid part are improved by a method wherein supply of ink in printing is regulated by using perforated thin paper. CONSTITUTION:As perforate thin paper to be stuck to a thermal shrinkage film, that of 12 to 25% in numerical aperture, 2.5X10<3> to 5.5X10<3>mum<2> in mean aperture area, and 1.10 to 0.16 gf.cm/cm<2> in compressive workload is used. As the thermal shrinkage film, that of polyethylene phthalate or the like which is excellent in low temperature shrinkage is used. As fiber comprising the perforate thin paper, natural fiber of Manila hemp or the like, of synthetic fiber of PET or the like is individually or are mixed to be used by selecting suitably type of fiber, mean fiber diameter, beating degree, etc., within a range of physical properties of paper. By regulating ink supply by using abovementioned thin paper, printed matter which is excellent in resolution of letters and characters, though it has been insufficient only by improvement of perforation property of the film itself, and of which uniformity and reverse printing property of a solid part are improved, can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a heat-sensitive stencil paper, and more particularly to a heat-sensitive stencil paper with excellent printing properties.

(Prior art) Various stencil printing methods have been known for a long time, but in recent years,
2. Description of the Related Art Heat-sensitive stencil printing, in which printing is performed by perforating a stencil paper made by bonding a heat-shrinkable film and porous thin paper with an adhesive using heat, has become widespread.

A method of perforating heat-sensitive stencil paper using heat is the so-called flash method, in which the stencil paper and the original are overlapped and irradiated with infrared rays, which adheres to the fibers of the porous thin paper and heat-shrinks the film portion surrounded on all sides to form perforations. A perforation method, or a so-called digital perforation method is known, in which the film surface of the thermal stencil paper is brought into contact with a thermal head, the thermal head is caused to generate heat, and the portion of the film that the thermal head comes into contact with is perforated when the thermal head generates heat.

The digital drilling method is becoming the mainstream drilling method due to the fact that there is less scumming during drilling compared to the flash drilling method.

In the digital drilling method, since the amount of heat generated by the thermal head is smaller than that in the flash drilling method, various proposals have been made to improve the drilling sensitivity with a lower amount of heat.

For example, Japanese Patent Application Laid-Open No. 61-53092 proposes a method of improving the perforability of the film by using porous thin paper with an aperture ratio of 40% or more in the portion that contacts the film.

(Problem to be Solved by the Invention) However, the reality is that after a perforated thermal stencil master is subjected to printing, it is not possible to obtain a sufficiently satisfactory printed matter simply by improving the perforation of the film. Met.

That is, even if the portion of the film that came into contact with the thermal head was sufficiently perforated to correspond to the heating dot portion of the thermal head, the resolution was insufficient such that the dots of the letters were poorly connected or the letters became thick.

In addition, the uniformity of the image quality is poor, such as the fiber shape (fiber grain) of the porous thin paper that is the support appearing in the printed image in solid areas, or the problem of white spots in the center of solid areas when printing multiple sheets. There was a point.

(Means for Solving the Problem) As a result of intensive studies to solve the above problems, the present inventors found that by adjusting the ink supply during printing using a specific porous thin paper, the resolution of characters could be improved. The inventors have discovered that it is possible to obtain a heat-sensitive stencil paper which has excellent printing characteristics such as uniformity of solid areas and white areas, and has arrived at the present invention.

That is, the present invention provides 1) a heat-sensitive stencil paper formed by bonding a heat-shrinkable film and a porous thin paper with an adhesive, the porous thin paper having a porosity of 12 to 25% and an average pore area of 2.5 x 103 to 5
．． 5X103μm2, compression work 0.10-0.16g
A heat-sensitive stencil paper characterized in that it uses a material with a diameter of f-cm/cm2.

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

It is related to.

In the present invention, the pores in porous thin paper are the parts that allow light to pass through and appear to form holes, and contribute to ink supply during printing, taking into account the state in which the thin paper is compressed by a press roll during printing. This refers to the hole that opens when pressure is applied.

Open area ratio (%) in the present invention, average open area (X103
μm2) and 6. OX 103B The area ratio (%) occupied by openings of m2 or more is determined by Ruzek I [D image analysis device (
(manufactured by Nireco Co., Ltd.). Porous tissue paper (1
0x10cm) on a 5mm thick transparent glass plate (10x10cm)
10cm) and then a 5mm thick transparent glass plate (
Taking into account the press pressure during printing, a 4.5 kg weight with a 1 x 1 cm hole in the center was placed on the glass plate (3 x 3 cm), and the porous thin paper was placed on top of the porous thin paper. With a load of 500gf/cm2 applied,
3× of the porous tissue paper through the hole part of the weight.
Magnify the 3mm part 50 times and adjust the focus to the center of the thickness, then change the position of the glass plate (3 x 3cm) and the weight to find the area of the aperture through which the light passes.
The numerical value calculated by integrating the 1o point measurement data is adopted.

Also, compression work in the present invention! (g f-cm/cm
2) Compression recovery (%) is determined by stacking 10 sheets of porous tissue paper.
Using an FB3 compression tester manufactured by Kadochik Co., Ltd., the material was compressed at a compression speed of 20 m1 cron/sec with a load from Ogf/cm2 to 50 gf/cm2, and from this compressed state, it was compressed at a speed of 20 m1 cron/sec. The average value of the compression work and compression recovery work when released at three arbitrary points is adopted. Furthermore, compression recovery work load/compression work load x 100 (%) is calculated as compression recovery (
%) is used.

Examples of heat-shrinkable films used in the present invention include polyethylene terephthalate, polyvinylidene fluoride, and polyvinylidene chloride films, but those with excellent low-temperature shrinkability are more preferably used from the viewpoint of perforation. The thickness is preferably approximately 1°5 to 5 μm. 1.
If it is less than 5 μm, it will be difficult to handle, and if it exceeds 5 μm, an excessive amount of heat will be required for perforation, making it impossible to obtain practical perforation.
25%, more preferably 14-20%, average open pore area 2
．． 5 X 103~5. 5 X] 031J, m
2, more preferably 2.5X10” to 4.5X103
JJ, m2, more preferably 2.5X103~3.
5X103μm2, compression work 0. 10-0. 16
gf・cm/Cm2, more preferably 0.13 to 0.1
There is no particular limitation as long as it is within the range of 6gf-Cm/Cm2.

If the above-mentioned aperture ratio is less than 12%, the amount of ink supplied will be insufficient, the dots of the characters will be poorly connected, the resolution will be poor, and the uniformity of the edges will also be poor, which is not preferable. Open area ratio is 25
If it exceeds %, the amount of ink supplied becomes excessive, resulting in thick characters, lowering resolution, and solid areas that consume a large amount of ink become blank, which is not preferable.

If the average opening area is less than 2.5 x 10311 m2, the amount of ink supplied is insufficient, and the dots of characters are poorly connected, resulting in poor resolution. If the average opening area exceeds 5.5 x 103 μm2, the amount of ink supplied is insufficient. This is undesirable because the characters become thicker, the resolution is lowered, and the solid printed area, which consumes a large amount of ink, is more likely to have white spots. Also, 6.0X10”μ
If the number of openings larger than m2 increases, even if the average opening area is within the above range, the characters will become partially thick and the resolution will decrease, resulting in unevenness. is within 20% of the total open pore area, more preferably 15%
It is more preferable that it is within the range.

Also, the amount of compression work is 0. 10 g f-cm/cm
If it is less than 2, the amount of compression recovery work is small and it is difficult to recover from the compressed state, so the actual amount of change in volume due to compression (hereinafter referred to as compression volume) is small, and the amount of compression by the press roll during printing is small. After that, when the compressed state is restored, the amount of ink taken into the porous tissue paper by the compressed volume portion is small, and areas where a large amount of ink consumption, such as solid areas, are affected by insufficient ink supply amount, which is preferable. do not have.

On the other hand, if the compression work exceeds 0.16 gf-cm/cm2, it is difficult to compress and the change in volume due to compression is small, so when the ink recovers 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, and areas where a large amount of ink is consumed, such as solid areas, are not preferred because the amount of ink supplied is insufficient and white spots appear.

The fibers constituting the porous thin paper of the present invention include, for example, natural fibers such as Manila hemp, kozo, and mitsumata, or PET,
Examples include synthetic fibers such as nylon and PP5 (polyphenylene sulfide), which can be used alone or in combination by appropriately selecting the type of fiber, average fiber diameter, degree of beating, etc. within the physical properties of the porous tissue paper mentioned above. . In the case of natural fibers, when the beating degree is low, both the porosity and the average pore area become large, and when the beating degree is high, the porosity and the average pore area are both small. J l5P8121)
fibers and freeness less than 20°SR, preferably 14-16
°SR fibers are approximately 40-60% by weight: 60-60%
It is more preferable to use 40% by weight in combination because the pore area is high and the average pore area can be reduced, resulting in improved resolution.

In the case of the digital perforation method, when perforating with a thermal head, the thermal head does not break through the film and comes into contact with the thin paper, so the Gurley stiffness (JIS L, -10) of the porous thin paper
It is more preferable to increase the strength of the porous thin paper by blending the fibers so that the amount of 79-5-17E) is approximately 3.0 mg or more because it is less likely to stick, and fibers with a melting point exceeding 260° C. are more preferably used.

Further, in order to increase the adhesion between fibers, a fibrous binder may be mixed in the paper as long as it does not cause sticking or impair printing properties.

As a method for making the porous thin paper used in the present invention using the above-mentioned fibers, a wet paper making method using an ordinary circular mesh paper machine or the like may be used, and in this case, paper strength enhancers, which are usually used, Paper-making aids such as dispersants may be used within a range that does not impede printing properties.

Next, the above-mentioned film and porous thin paper are laminated with an adhesive, and if necessary, an anti-sticking layer is provided on the film surface to prepare a heat-sensitive stencil paper.

The above-mentioned adhesive is not particularly limited as long as it is thermoplastic and can bond the film used and the porous thin paper, and examples thereof include vinyl acetate, acrylic, and polyester adhesives.

Furthermore, examples of the above-mentioned anti-sticking layer include those having mold release properties such as surfactants, lubricants, and silicone.

(Effect of the invention) By adjusting the ink supply by using a porous thin paper used for heat-sensitive stencil paper whose porosity, average pore area, and compression work are within specific ranges, the film itself The present invention provides a heat-sensitive stencil paper having excellent character resolution, uniformity of solid areas, and improved printing characteristics, which was not sufficient if the perforation of the paper was improved.

(Examples) The present invention will be explained in detail below using Examples, but the present invention is not limited to these Examples.

Note that the evaluation method in the examples is as follows.

1) Deformation of solid perforated area after plate making Visual judgment was made according to the following ranking.

○ No deformation 8 Slight deformation × Severe deformation 2) Resolution The connection of the dots and the thickness of the characters were visually judged according to the following criteria.

◎ Very good ○ Good Δ The dots are slightly unconnected. Or slightly overweight.

X The dots are poorly connected. Or, the text is thick and difficult to read.

3) Uniformity of solid areas Visual judgment was made according to the following ranking.

O good 8 Slightly inferior × Bad 4) The white part of the solid part is Visual judgment was made according to the following ranking.

O Good Δ Slightly A porous thin paper having the properties shown in Table 1, such as basis weight, porosity, average closed pore area, compression work and compression recovery, is produced by wet paper making using a circular mesh paper machine using a mixture of was created.

Next, a 2.5 μm heat-shrinkable PET film and a polyester adhesive (manufactured by Konishi Bond Co., Ltd., product name KV-3) were used.
5) Each was laminated through 0.6 g/m2 (solid content).

Furthermore, 0.3 g/m2 of a silicone surfactant was applied to each of the laminated film surfaces to prepare a heat-sensitive stencil paper.

Using the thermal stencil paper obtained in the above manner as the image electrophotography society test chart No. 2 as a manuscript, Gakken 0DX-2020 plate making machine with digital perforation method (manufactured by Gakken Co., Ltd.)
After making a plate and evaluating the deformation state of the solid plate making area, printing was performed using a RISOGRAPH AP7200 printing machine (manufactured by Riso Kagaku Kogyo Co., Ltd.), and the printing characteristics were evaluated.

The results obtained are shown in Table-2.

Example 2 A circular net was made using a mixture of 40 parts by weight of fibers obtained by beating Manila hemp with an average fiber diameter of 10 μm to a beating degree of 306 SR and 60 parts by weight of fibers obtained by beating Manila hemp with an average fiber diameter of 14 μm to a beating degree of 16° SR. Porous thin paper having the properties shown in Table 1, such as weightage, porosity, average pore area, compression work, and compression recovery, was produced using a wet papermaking method using a type paper machine.

Next, a heat-sensitive stencil paper was prepared in the same manner as in Example 1, plate-making and printing were performed in the same manner as in Example 1, and the plate-making characteristics and printing characteristics were evaluated.

The results obtained are shown in Table-2.

=13 Example 3 Manila hemp with an average fiber diameter of 14) and tm was beaten to a beating degree of 28°SR! 1180 parts by weight and average fiber diameter 14μ
A mixture of 20 parts by weight of fibers beaten to 15° SR of Manila hemp of 500 m was used to make wet paper using a circular mesh paper machine to produce the tsubo, porosity, and average pore size shown in Table I. area,
Porous tissue paper with characteristics such as compression work and compression recovery was produced.

Next, a heat-sensitive stencil paper was prepared in the same manner as in Example 1, plate-making and printing were performed in the same manner as in Example 1, and the plate-making characteristics and printing characteristics were evaluated.

The results obtained are shown in Table-2.

Example 4 Wet paper was made using a circular wire paper machine using a mixture of 30 parts by weight of PET fibers with an average fiber diameter of 811 m and 20 parts by weight of fibers obtained by beating Manila hemp with an average fiber diameter of 14 μm to a beating degree of 28° SR. Porous thin paper having the properties shown in Table 1, such as basis weight, porosity, average pore area, compression work, and compression recovery, was produced by the method.

Next, a heat-sensitive stencil paper was prepared in the same manner as in Example 1, plate-making and printing were performed in the same manner as in Example 1, and the plate-making characteristics and printing characteristics were evaluated.

The results obtained are shown in Table-2.

Example 5 35 parts by weight of fibers made by beating Manila hemp with an average fiber diameter of 12 μm to a beating degree of 28° SR, 35 parts by weight of fibers made by beating Manila hemp with an average fiber diameter of 14 μm to a beating degree of 15° SR, and PPS fibers with an average fiber diameter of 8 μm Using a mixture of 30 parts by weight and a wet paper making method using a circular wire paper machine, the properties such as tsubo, porosity, average pore area, compression work and compression recovery properties shown in Table 1 were determined. A porous tissue paper having the following structure was prepared.

Next, a heat-sensitive stencil paper was prepared in the same manner as in Example 1, plate-making and printing were performed in the same manner as in Example 1, and the plate-making characteristics and printing characteristics were evaluated.

The results obtained are shown in Table-2.

Comparative Example 1 Manila hemp with an average fiber diameter of 14 μm was beaten to a degree of beating of 28° SR, and the basis weight, pore area, and average pore area shown in Table 1 were produced using a wet paper making method using a circular mesh paper machine. Porous tissue paper with characteristics such as compression work and compression recovery was produced.

Next, a heat-sensitive stencil paper was prepared in the same manner as in Example 1, plate-making and printing were performed in the same manner as in Example 1, and the plate-making characteristics and printing characteristics were evaluated.

The results obtained are shown in Table-2.

Comparative Example 2 A mixture of 20 parts by weight of Manila hemp with an average fiber diameter of 14 μm beaten to a beating degree of 21° SR and 80 parts by weight of fibers made of Manila hemp with an average fiber diameter of 14 μm beaten to a beating degree of 15° SR was used. Porous tissue paper having the characteristics shown in Table 1, such as basis weight, porosity, average pore area, compression work, and compression recovery, was produced using a wet papermaking method using a circular mesh paper machine.

Next, a heat-sensitive stencil paper was prepared in the same manner as in Example 1, plate-making and printing were performed in the same manner as in Example 1, and the plate-making characteristics and printing characteristics were evaluated.

The results obtained are shown in Table-2.

Comparative Example 3 Using PET fibers with an average fiber diameter of 9 μm, the wet paper making method was performed using a circular mesh paper machine to obtain the results shown in Table 1, such as basis weight, porosity, average pore area, compression work, compression recovery, etc. A porous thin paper with special characteristics was fabricated.

Next, a heat-sensitive stencil paper was prepared in the same manner as in Example 1, plate-making and printing were performed in the same manner as in Example 1, and the plate-making characteristics and printing characteristics were evaluated.

The results obtained are shown in Table-2.

Comparative Example 4 Wet paper was made using a circular mesh paper machine using a mixture of 50 parts by weight of PET fibers with an average fiber diameter of 9 μm and 50 parts by weight of fibers obtained by beating Manila hemp with an average fiber diameter of 10 μm to a beating degree of 28°SR. Porous thin paper having the properties shown in Table 1, such as basis weight, porosity, average pore area, compression work, and compression recovery, was produced by the method.

Next, a heat-sensitive stencil paper was prepared in the same manner as in Example 1, plate-making and printing were performed in the same manner as in Example 1, and the plate-making characteristics and printing characteristics were evaluated.

The results obtained are shown in Table-2.

Table-2

Claims (1)

[Scope of Claims] 1) A heat-sensitive stencil paper made by bonding 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 pore area of 2.5. ×10＾3～
5.5 x 10^3μm^2, compression work 0.10-0.
A heat-sensitive stencil paper characterized by using 16gf.cm/cm^2. 2) The heat-sensitive stencil paper according to claim 1, wherein a porous thin paper having a Gurley stiffness of 3.0 mg or more is used. 3) The heat-sensitive stencil paper according to claim 1 or 2, wherein fibers having a melting point of over 260° C. are used as the fibers of the porous thin paper.