JPH09250100A - Stencil printing paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a stencil printing paper suitable as e.g. a color stencil printing paper excellent in ink absorbing ability, color clearness and dot reproducibility by providing a substrate with specific ink absorbing layer(s). SOLUTION: This stencil printing paper is obtained by providing a substrate such as paper <=20 s in Steckigt sizing degree with at least one ink absorbing layer (pref. at 2-10g/m<2> ) consisting mainly of a binder and a loading material >=200m<2> /g in specific surface area and >=150mL/100g in oil absorption in the weight ratio of (100:10) to (100:50). Preferably that Bekk smoothness of the paper surface bearing the ink absorbing layer(s) is 20-150 s.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to printing paper used for stencil printing, and particularly to printing useful for color stencil printing using multicolor inks, which is excellent in ink absorbency, clearness, dot reproducibility and the like. Regarding paper.

[0002]

2. Description of the Related Art In recent years, stencil printing using heat-sensitive perforation has become widely used as simple printing because a plate can be easily prepared by a digital method, automation is advanced and operation is simplified. Plate making in stencil printing is generally carried out by heat-melting a film with a thermal head or the like using a stencil printing base paper made of a thermoplastic resin film to perform perforation printing for plate making. Printing is performed through the perforated portion of the perforated image formed in this way, and ink is passed from the ink supply side through the perforated portion and transferred to the surface of a printing material such as paper for printing.

Since stencil printing, which is widely used at present, is based on maintenance-free simple printing, no washing treatment is performed after printing, and even if the ink is left on the plate for a long time until the next printing, It is demanded that a good printed matter can be obtained immediately after the next printing even under various environments without causing clogging of the perforated portion due to drying. Therefore, stencil printing inks generally have a structure in which a large amount of water is emulsified in a high-boiling oil in which a colorant is dispersed, and a printing ink of a water-in-oil type that does not cure on standing has been used and various improvements have been made. Was. Therefore, in stencil printing, a water-in-oil emulsion ink composed of an oil phase component and an aqueous phase component is always kept in a stable state even when the ink is left on the printing plate surface for a long time, and maintenance-free simple printing is performed. It can be said that the ink is in a preferred form for performing the above.

In stencil printing, however, a large amount of non-volatile mineral oil and water-based ink is transferred to the printing paper even though the ink is suppressed in drying property on the plate surface as described above. Also, the drying of the printed surface after printing is slow because the permeation drying type ink is mainly applied to the printing material by a cold set type printing machine, so the drying is slow, and the undried ink after printing is the back side of the next printed material. However, problems such as so-called set-off and stain during handling of printed matter have occurred, which has been a problem for many years.

Further, the dot reproducibility by stencil printing is the accuracy of perforation during plate making, control of the amount of ink transfer during printing, and when the ink on the printing surface is permeated and absorbed by the ink between the paper layers by permeation drying. The dot gain is large due to bleeding along the fibers of the dot shape, and the dot shape is also irregular and irregular.
The dot reproducibility is deteriorated, the sharpness is lacking, the print quality is lower than that of an ordinary offset printed matter, and improvement in quality is also required.

[0006] Therefore, in order to achieve both the on-machine leaving stability when the ink is left on the plate surface for a long time and the prevention of back-sliding after printing, and further to improve the printing quality, the printing base paper, ink, Many proposals have been made from papers, devices, etc. Although the number of applications from the paper side is small, for example, JP-A-6-331796 in which an ink fixing layer of diatomaceous earth as a pigment and a binder is provided, the oil absorption amount is 45 ml / 10.
JP-A-6-171201 provided with an ink absorption layer of a pigment and a binder of 0 g or more and 120 ml / 100 g or less.
Etc. However, even with these measures, it is a satisfactory solution to obtain printed matter with good dot reproducibility without causing set-off without degrading maintenance-free on-machine leaving stability, which is an advantage of stencil printing. Has not arrived.

In the stencil printing method, uncoated paper is generally used as the paper, but the transfer amount of ink supplied to the paper is much larger than that of other printing methods such as offset printing. In the conventional printing paper, the ink absorbency is limited, so that when a large amount of ink is transferred, the drying property of the ink is slow and backslip cannot be avoided. In particular, when multicolor overprinting is performed by color printing using a multicolor ink in which a plurality of inks are printed one after another, the next printing is performed over the printed colors, and thus, for example, different 3 In the case of printing with color inks, the ink transfer amount is tripled, and it is difficult to rapidly permeate and dry the emulsion ink mainly composed of water and a non-volatile mineral oil, and the drying property and the dot reproducibility are further deteriorated.

By the way, the present inventors have examined not only uncoated paper but also ordinary coated paper. Although the dot reproducibility is improved by the coating layer, the printing density is low, and the drying property and fixing property are low. It was found that the performance is significantly lower than that of uncoated paper. This is because the coating layer consisting of the filler and the binder reduces the ink absorbability by the binder, and the pressure of the calender process further reduces the voids in the coating film due to the deformation of the binder resin and the layer, which slows the ink absorption.
It is also considered that the transferability of the ink is deteriorated. It is also possible to thicken the ink absorbing layer to thicken the porous layer in order to impart sufficient ink absorbing property, but in this case, the paper-like property is lost, and the so-called filler is removed, so-called This causes a problem of powder falling.

[0009]

SUMMARY OF THE INVENTION The object of the present invention is to perform cold-set type printing using an ink that does not change even after being left for a long time on the plate surface of a printing press and is held in a stable state. Even after printing, the undried ink does not transfer to the back surface of the next printing paper, so-called back wandering does not occur, and there is a print quality with excellent dot reproducibility, and it is to provide stencil printing paper, It is an object of the present invention to provide a printing paper suitable for color stencil printing, in which multicolor overprinting is performed using multicolor inks in which a plurality of inks are printed one after another.

[0010]

According to the present invention, firstly, in a stencil printing paper comprising at least one ink absorbing layer provided on a support, the ink absorbing layer has a specific surface area of 200 m ² / g. The oil absorption is 150 ml / 100
Provided is a stencil printing paper, which comprises g or more of a filler and a binder as main components. Secondly, there is provided the stencil printing paper according to the first aspect, characterized in that an ink absorbing layer is provided on at least one surface of a paper having a Steckigt sizing degree of 20 seconds or less. Thirdly, there is provided a stencil printing paper characterized in that the coating amount of the ink absorbing layer described in the first and second is in the range of ² to 10 g / m ² .
Fourthly, there is provided a stencil printing paper characterized in that the Bekk smoothness of the surface of the stencil printing paper provided with the ink absorbing layer is in the range of 20 to 150 seconds. Fifth, the filler / binder (weight ratio) constituting the ink layer is 100/10 to 10
A stencil printing paper is provided which is 100/50. Sixth, there is provided a color stencil printing paper comprising the stencil printing paper according to any one of the above first to fifth.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
A feature of the printing paper of the present invention is that an ink absorption layer containing a filler having a specific specific surface area and a specific oil absorption and a binder as main components is provided on the support. Generally, in stencil printing, a water-in-oil emulsion ink having an oil phase component of about 20 to 50% by weight transfers to about 10 g / m ² paper, and the oil phase component is non-volatile and remains in the paper. If this results in color printing using a plurality of color inks, the transfer amount of the ink will be several times that amount. For this reason, in the conventional stencil printing paper, the ink absorption layer was made thicker, and a means for increasing the absorption and preventing set-off was taken, but such a printing paper has a significantly large coating amount, and therefore cost is low. Since the ink absorption layer becomes high and the ink absorption layer becomes thick, the paper-like property is lost, and a so-called powder falling phenomenon occurs due to the dropping of the filler.

The inventors of the present invention have made earnest studies on a stencil printing paper which has a small coating amount, is excellent in ink absorption, has no set-off, and does not have powder fall-off in paper-like. And has a BET specific surface area of 200 m ² / g or more, preferably 200 to
350 m ² / g, oil absorption amount according to JIS K5101 is 150 ml / 100 g or more, preferably 200 to 300 m
It was found that the above problems can be solved by using 1/100 g of the filler and the binder, and the present invention has been completed.

That is, in the present invention, the specific surface area of the ink absorption layer according to the BET method is 200 m ² / g or more, preferably 200 to 350 m ² / g, and JIS K5101 is used.
Oil absorption by 150 ml / 100 g, preferably 200
˜300 ml / 100 g of filler and binder are included. When the BET specific surface area is less than 200 m ² / g and the oil absorption is less than 150 ml / 100 g, the ink absorbency is lowered, the ink setting property and the drying property are slow, and the set-off occurs, and the ink absorbability is sufficient. There is a problem that the ink absorption layer must be thickened in order to impart the property. In addition, the specific surface area by the BET method is 200 m ² /
If the oil absorption is less than 150 g and the oil absorption is more than 150 ml / 100 g, or if the oil absorption is less than 150 ml / 100 g and the specific surface area is more than 200 m ² / g, the ink absorptivity is lowered and sufficient ink setting property and drying are obtained. I can't get sex. If the specific surface area exceeds 350 m ² / g, the hardness of the filler will gradually become soft, making it difficult to write with a pencil or the like. In addition, powder is likely to fall off. Oil absorption is 300m
A similar tendency is observed in the case of a filler exceeding 1/100 g.

Examples of the filler that can be used in the present invention include calcium carbonate, calcium sulfate, barium sulfate, talc, calcined clay, kaolin, silica, zeolite, aluminum hydroxide, satin white, titanium oxide, aluminum silicate, Inorganic pigments such as magnesium silicate and organic pigments of styrene resin, acrylic resin, urea resin and melamine resin, which satisfy the above conditions, are arbitrarily used. When two or more fillers are used in combination, it is sufficient that the combined use satisfies the above conditions.

Examples of the binder that can be used in the present invention include polyvinyl alcohol and its derivatives, polyvinylpyrrolidone, starch and its derivatives, cellulose derivatives, gelatin, casein, styrene-butadiene copolymers and vinyl acetate copolymers. In addition to organic binders such as coalesced and acrylic copolymer latex, there are inorganic binders such as colloidal silica and alumina sol. These can be used alone or in admixture of two or more.

The use ratio of the filler and the binder for forming the ink absorbing layer is 10 to 50 parts by weight, preferably 15 to 35 parts by weight, based on 100 parts by weight of the filler. Further, the ink absorbing layer is preferably a porous layer having many voids for absorbing ink. In this case, if the binder is used in an amount of more than 50 parts by weight, the void structure is reduced and the ink absorbency is lowered.
On the other hand, if the amount is less than 10 parts by weight, a sufficient binding effect for the filler cannot be obtained, which causes powder falling off, which is not desirable.

The support used in the present invention preferably has a Steckigt sizing degree of 2 according to JIS P8122.
Fine paper of 0 seconds or less is used. The emulsion ink for stencil printing according to the present invention is quickly absorbed by the highly oil-absorptive filler of the ink absorption layer at the time of printing, but the ink absorption layer is made as thin as possible to ensure sufficient ink absorption. It is necessary to rapidly adsorb the ink reaching the base paper, and the water-in-oil emulsion ink used for stencil printing contains a large amount of water phase component of 50% or more,
In the ink, the oil phase component having high permeability penetrates into the paper first, and the water phase component permeates afterwards, but in the case of a paper having a high sizing degree, the permeation speed becomes slow and the drying property of the ink deteriorates. For this reason, in the present invention, as described above, it is desirable to use a base paper having a Steckigt sizing degree of 20 seconds or less as a support. If the Steckigt sizing degree exceeds 20 seconds, the ink absorption becomes insufficient, and it is not desirable because the ink absorption layer needs to be thickened in order to maintain the absorption. Further, when the Steckigt sizing degree approaches 0 second, the water-soluble coating liquid permeates quickly, making uniform coating difficult.

By providing the ink absorbing layer according to the constitution of the present invention, the ink absorbing property, the dot reproducibility and the sharpness can be obtained with a small coating amount, and the sufficient ink absorbing property can be secured by the base paper having the low size. . The coating amount of the ink absorbing layer is ^{2 to} 10 g / m ^2, preferably 4 to 8 g / m ² . If the coating amount is less than 2 g / m ² , the ink absorbency is insufficient and the drying is slow, the dot shape and dot gain are poor, and if it exceeds 10 g / m ² , powder drop occurs and the paper-like property is lacking. come.

In the present invention, it is preferable that the surface of the stencil printing paper is smoothed to remove corrugations and wrinkles. In this case, the smoothness is a Beck's smoothness according to JIS P8119 for 20 to 150 seconds, preferably 30 to 10 seconds.
The range of 0 seconds is desirable. Beck smoothness is 20
If it is less than seconds, the surface is rough and the print quality is deteriorated. On the other hand, if it exceeds 150 seconds, the filler particles are densely packed, the voids of the ink absorbing layer are reduced, the ink absorbing property is deteriorated and the drying property is deteriorated.
In addition, the transferability of the ink and the sheet feeding / conveying property during printing are impaired, which is not preferable.

In the present invention, as described above, the coating liquid for the ink absorbing layer contains a filler and a binder as main components, but the coating liquid may contain a conventionally known dispersant and a thickener, if necessary. You may mix | blend an agent, a fluorescent whitening agent, an ultraviolet absorber, etc. suitably. As a coating machine for providing the ink absorbing layer on the base paper, various commonly used coaters such as a blade coater, an air knife coater, a bar coater, and a roll coater can be used on-machine or off-machine.
It is appropriate to use on-machine in terms of cost. Further, in order to obtain a predetermined smoothness, it is possible to perform smoothing processing with a machine calendar or the like.

[0021]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. All parts and% in the text are based on weight.

Example 1 Synthetic silica (Mizukasil P-78A, manufactured by Mizusawa Chemical Industry Co., Ltd., oil absorption 250 ml / 100 g, specific surface area 320 m ²
/ G) 10 parts, polyvinyl alcohol (PVA117
(Kuraray Co., Ltd.) 2.5 parts with water to a solid concentration of 16%,
Dispersed into a coating liquid. The coating liquid was applied using a wire bar coater on a single side of high-quality paper having a Steckigt sizing degree of 5 seconds and a basis weight of 80 g / m ² using a wire bar coater such that the coating amount after drying was 5 g / m ² . . Further, calendering was performed so that the smoothness was 50 seconds to obtain the stencil printing paper of the present invention.

Example 2 Synthetic silica (Fineseal X37, manufactured by Tokuyama Soda Co., Ltd., oil absorption 280 ml / 100 g, specific surface area 270 m ² / g)
10 parts, silanolated polyvinyl alcohol (PVA
R-1130 (manufactured by Kuraray Co., Ltd.) (2.5 parts) was mixed and dispersed with water to a solid content concentration of 16% to obtain a coating liquid. The coating liquid was applied using a wire bar coater on a single side of high-quality paper having a Steckigt sizing degree of 5 seconds and a basis weight of 80 g / m ² using a wire bar coater such that the coating amount after drying was 5 g / m ² . . Further, calendering was performed so that the smoothness was 50 seconds to obtain the stencil printing paper of the present invention.

Example 3 Synthetic silica (Fineseal X37, manufactured by Tokuyama Soda Co., Ltd., oil absorption 280 ml / 100 g, specific surface area 270 m ² / g)
10 parts, colloidal silica (Snowtex 20, Nissan Chemical Co., Ltd.) 1 part, silanolated polyvinyl alcohol (PVA R-1130 manufactured by Kuraray Co., Ltd.) 2.5 parts were mixed and dispersed with water to a solid content concentration of 16%, and applied. It was a liquid. Using this coating liquid, a stencil printing sheet of the present invention was obtained under the same conditions as in Example 1.

Examples 4 to 6 In Example 1, synthetic silica (Mizukasil P-78) was used.
A, manufactured by Mizusawa Chemical Co., Ltd., oil absorption 250 ml / 100 g,
A printing paper of the present invention was obtained under the same conditions as in Example 1 except that 10 parts of the specific surface area of 320 m ² / g) was changed as follows. Example 4 Synthetic silica: Mizukasil P-73 (manufactured by Mizusawa Chemical Industry Co., Ltd., oil absorption 150 ml / 100 g, specific surface area 32)
0 m ² / g) Example 5 Synthetic silica: Mizuka soap C-1 (manufactured by Mizusawa Chemical Industry Co., Ltd., oil absorption 220 ml / 100 g, specific surface area 41)
0 m ² / g) Example 6 Synthetic silica: Carplex FPS-1 (Shionogi Pharmaceutical Co., Ltd., oil absorption 236 ml / 100 g, specific surface area 200 m ² / g)

Examples 7 to 9 In Example 1, Stoeckigt sizing degree of 5 seconds and basis weight of 80
Example 1 except that the fine paper of which the Steckigt sizing degree of the fine paper of g / m ² was changed to 1 second (Example 7), 20 seconds (Example 8) and 30 seconds (Example 9) was used. A stencil printing paper was obtained in the same manner as in.

Examples 10 to 12 In Example 1, the dried ink absorption layer was 1 g / m ^2.
(Example 10), 10 g / m ² (Example 11), 15 g
/ M ² (Example 12), and the stencil printing paper was obtained in the same manner as in Example 1 except that coating and drying were performed.

Examples 13 to 16 In Examples 1, smoothness by filler coating and calendering after drying was 10 seconds (Example 13), 20 seconds (Example 14), 150 seconds (Example 15), 200 seconds (Example 1
A stencil printing paper was obtained in the same manner as in Example 1 except that each of 6) was finished.

Examples 17 to 20 In Example 1, polyvinyl alcohol (PVA 1
17 Kuraray Co., Ltd. 2.5 parts to 0.5 parts (Example 1)
7), 1.0 part (Example 18), 5.0 parts (Example 1)
9) and stencil printing paper were obtained in the same manner as in Example 1 except that 7.0 parts (Example 20) were used.

Comparative Examples 1 to 4 In Example 1, synthetic silica (Mizukasil P-78) was used.
A, manufactured by Mizusawa Chemical Co., Ltd., oil absorption 250 ml / 100 g,
A stencil printing sheet of the present invention was obtained under the same conditions as in Example 1 except that 10 parts of the specific surface area of 320 m ² / g) was changed as follows. Comparative Example 1 Synthetic silica: Mizukasil P-87 (manufactured by Mizusawa Chemical Industry Co., Ltd., oil absorption 140 ml / 100 g, specific surface area 30)
0 m ² / g) Comparative Example 2 Synthetic silica: Carplex XR (manufactured by Shionogi & Co., oil absorption 233 ml / 100 g, specific surface area 172)
m ² / g) Comparative Example 3 Synthetic silica: Carplex FPS (manufactured by Shionogi & Co., oil absorption 135 ml / 100 g, specific surface area 14)
4 m ² / g) Comparative Example 4 Synthetic silica: Mizukasil P-832 (manufactured by Mizusawa Chemical Industry Co., Ltd., oil absorption 140 ml / 100 g, specific surface area 5)
4m ² / g)

Comparative Example 5 A stencil printing paper was prepared in the same manner as in Example 1 except that the quality paper of Example 1 was replaced with a quality paper of Steckigt sizing degree of 30 seconds and a basis weight of 80 g / m ² without an ink absorbing layer. Got

For the stencil printing paper of each of the examples and comparative examples obtained as described above, Preport VT3820 (manufactured by Ricoh) was used as a stencil printing machine, and the water-in-oil emulsion for stencil printing was used as the ink. Ink (Preport Ink VT-500 Black Ricoh Co., Ltd.) was used to print at a printing speed of 80 sheets / min, and the suitability was evaluated by the following method. Table 1 shows the results. [Ink set-off]: Visual observation of the degree of ink stains on the back surface of the printed matter by continuous printing of 20 test pattern charts, and after 5 seconds and 10 seconds from the completion of printing, superimposing high-quality paper and applying a constant load of 50 g / cm ^2. The degree of ink adhesion on the high-quality paper surface after it has been exposed is measured by the Macbeth reflection densitometer RD9.
No. 14 was used, and the overall evaluation was performed by comparing with the density, and evaluated as O, Δ, and X. ⊚: Almost no ink set-off occurs ○: There is some 〃 △: 〃 is slightly conspicuous ×: Significant 〃 [Dot shape]: The shape of dots is visually observed from the printed matter of the test pattern chart. ◎: Almost circular shape ○: Circular shape is somewhat broken △: Circular shape but uneven and broken ×: Indefinite shape [Dot gain]: Perforation punched on the base paper by thermal perforation With respect to the hole diameter (circle: diameter 50 μm), the diameter of the printed dots was measured by a microscope and evaluated. [Ink bleeding]: From the printed matter of the test pattern chart, resolution evaluation and bleeding around the dots were evaluated by ⊚, ◯, Δ, and x by observing with a microscope. ◎: Almost no ink bleeding ○: There is a little 〃 △: 〃 is a little conspicuous ×: Significant 〃 is marked [lab off]: A test pattern chart is printed, and after 1 hour, the printed surface is lightly rubbed several times with fingers. The degree of ink removal was visually determined. ◎: Almost no ink is removed ○: There is some 〃 △: 〃 is a little noticeable ×: 〃 is remarkable

[0033]

[Table 1]

Example 21 Using the stencil printing paper prepared in Example 1, a stencil printing machine (preport VT3820) was used and a printing speed of 8
The next overprinting was performed 10 seconds after printing at 0 sheets / minute with the black ink on the test pattern chart.

Comparative Example 6 Example 2 was carried out using the stencil printing paper prepared in Comparative Example 1.
The same overprinting as in No. 1 was performed.

Example 22 Using the stencil printing paper prepared in Example 1, a stencil printing machine (preport VT3820) was used, and a printing speed of 8
Overprinting was sequentially performed 10 seconds after each printing with the yellow, magenta, and cyan inks on the test pattern chart at 0 sheets / minute.

Comparative Example 7 Example 2 was conducted using the stencil printing paper prepared in Comparative Example 1.
The same overprinting as in No. 2 was performed.

With respect to the printing states of Example 21, Example 22, Comparative Example 6 and Comparative Example 7, the following items were evaluated for suitability. Table 2 shows the results. Ink set-off: Evaluated by the degree of ink stain on the back surface of the printed matter by each continuous printing, and the quality paper overlay after 10 seconds of printing. Dot reproducibility: Microscopic observation of dot shape. Ink bleed: Same as above. The judgment criteria are the same as in the case of the four-step method.

[0039]

[Table 2]

[0040]

EFFECTS OF THE INVENTION The stencil printing paper of the present invention can reduce the coating amount of the ink absorbing layer because of the use of the filler having the specific high specific surface area and high oil absorption described above, and has a low binder ratio. This makes it possible to provide a porous and highly absorbent ink absorbing layer without reducing voids in the ink absorbing layer. Therefore, the stencil printing paper of the present invention suppresses the spread of ink dots from the perforated original plate of the stencil printing by the absorption layer having good ink absorption, so that the ink absorption is improved and the ink setting property and the drying property are improved. In addition, it provides printed matter with excellent dot reproducibility without set-off. If a paper having a Steckigt sizing degree of 20 seconds or less is used as the base paper, or if the Beck smoothness of the paper surface is 20 to 15
When it is set to 0 seconds, the ink setting property and drying property are further improved,
In addition, there is no set-off and a printed matter with excellent dot reproducibility is provided. In particular, when the printing paper of the present invention is used for color printing by overprinting using a plurality of color inks, a printed matter having good dot reproducibility without offset, bleeding due to color overlaying can be obtained. Therefore, the printing paper of the present invention is particularly suitable for color stencil printing that performs multicolor overprinting using multicolor inks in which a plurality of inks are printed one after another.

Claims (6)

[Claims] 1. A stencil printing paper comprising at least one ink absorbing layer provided on a support, wherein the ink absorbing layer has a specific surface area of 200 m ² / g or more and an oil absorption of 150 m.
A stencil printing paper comprising a filler and a binder as main components in an amount of 1/100 g or more. 2. The stencil printing paper according to claim 1, wherein an ink absorbing layer is provided on at least one side of a paper whose support has a Steckigt sizing degree of 20 seconds or less. 3. The coating amount of the ink absorbing layer is 2 to 10 g / m.
Stencil printing sheet according to claim 1 or 2, characterized in that in the ^second range. 4. The stencil printing paper according to claim 1, wherein the Bekk smoothness of the paper surface provided with the ink absorbing layer is in the range of 20 to 150 seconds. 5. Use ratio of filler and binder (weight ratio)
Is 100/10 to 100/50, The stencil printing paper according to any one of claims 1 to 4, wherein. 6. A color stencil printing paper comprising the stencil printing paper according to claim 1.