JPH04221697A - Tissue paper for high image property thermal stencil paper - Google Patents

Abstract

PURPOSE:To markedly enhance the image properties of printed matter by reducing the mean diameter of the fiber of tissue paper for heat sensitive stencil paper and uniformizing the dispersibility thereof. CONSTITUTION:Tissue paper for stencil paper is prepared by applying resin processing to tissue paper formed from blended fibers consisting of a natural fiber and 20-80wt.% of two or more kinds of chemical fibers with filament size of 1 denier or less and fiber length of 15mm or less by a papermaking process.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is applicable to flash irradiation from a xenon lamp or the like, pulsed infrared irradiation from a laser oscillation element, or direct or indirect radiation from a so-called thermal head having a large number of minute heating elements. This paper relates to a porous thin paper used as a base paper for thermal stencil printing which is thermally plated by heating by contact heat transfer.

0002

[Prior Art] Conventionally, thermoplastic resin films such as polyester films and vinylidene chloride films,
Heat-sensitive stencil printing base paper (hereinafter abbreviated as base paper) has a structure in which thin paper, non-woven fabric, gauze, etc. mainly composed of natural fibers or chemical fibers is used as a porous support, and the two are bonded together with various adhesives. known (for example, Japanese Patent Application Laid-Open No. 51-2513
(Japanese Patent Application Laid-Open No. 182492/1982, etc.).

However, these base papers do not satisfy the sharpness of printed images.

0004

[Problems to be Solved by the Invention] There are various possible reasons why the image clarity of printed matter using conventional base paper is not sufficient, but one of the major reasons for this is the problem of white spots (white spots in printed matter), which are unique to stencil printing. There is a phenomenon called white defects (occurring in solid black areas). This is because if several fibers constituting the support are aggregated to form a bundle in the part where the base paper film should originally be melted and perforated, then only the part corresponding to the bundled fiber part is present. This occurs because the pores are obstructed, and as a result, the permeation of printing ink is reduced, leaving the fiber shape as it is in white in the solid black area of the printed matter. In addition, if the film residue that has spread around the periphery of the holes opened after plate making is concentrated and aggregated in a certain area, that area may inhibit ink penetration and remain white. Furthermore, another important factor is that during plate making, the adhesion between the thermal head and the base paper film is poor, resulting in unperforated areas.

[0005] Therefore, in order to improve image clarity, it is important to improve the support. Specifically, 1. 2. Preventing support fiber binding to prevent white spots resulting from fiber binding; 2. By reducing the fiber diameter, the bonding points with the film can be made smaller and more evenly distributed, and the film residue after plate making can be evenly distributed; 3.
．． Three points are considered to be very important: making the support fibers evenly present in order to ensure uniform adhesion with the thermal head.

[0006] However, in thin paper made using only natural fibers such as Manila hemp, the distribution of fiber diameters is relatively large;
Moreover, since the shape of the fibers is non-uniform, non-uniform entanglement of the fibers is unavoidable, and it is difficult to prevent both the support fibers from bunching and the uniform distribution of the fibers to a satisfactory degree. There wasn't. In addition, in thin paper made using only synthetic fibers such as polyethylene terephthalate (PET) fibers, the fiber diameter is small and uniform;
On the contrary, the fibers tend to line up several at a time, resulting in non-uniform dispersion.In addition, this thin paper is easily deformed by heat during plate making, and the stiffness of the thin paper itself is low, which poses many practical problems.

[0007] In order to solve these problems, the present applicant has already developed a thin paper made by adding synthetic fibers to natural fibers and applying resin processing, as filed in Japanese Patent Application Laid-Open No. 1-271293. We have developed a support with higher image quality compared to conventional base paper supports. However, although base paper using this thin paper has improved image quality compared to conventional base paper, the dispersibility of natural fibers and synthetic fibers is uneven.
There was a need for an improved, more even fiber arrangement.

[0008] Therefore, in order to specifically solve these problems, there is a need for a thin paper that uses fibers with a small diameter and evenly disperses the fibers.
An important issue was how to make the thin paper, including other necessary physical properties (rigidity, printing durability, etc.).

[0009]

[Means for Solving the Problems] The present inventors conducted research to reduce the average fiber diameter of the fibers constituting the tissue paper and to improve its uniform dispersibility in thin paper made by mixing natural fibers and chemical fibers. As a result of intensive research, we have developed a thin paper with significantly improved image quality by adding two or more types of chemical fibers to natural fibers.

That is, the present invention provides two or more types of chemical fibers having a single yarn fineness of 1 denier or less and a fiber length of 15 mm or less.
Containing ~80% by weight, basis weight 5-15g/m2, thickness 1
This porous thin paper is 0 to 50 μm thick and is characterized by containing 3 g/m 2 or less of a synthetic resin on the surface of its fibers and in the intertwined portions of the fibers. The effect of mixing two or more types of chemical fibers with natural fibers may be due to the fact that the presence of different types of fibers reduces the affinity between the fibers, compared to when each type of chemical fiber is mixed individually. Since the fiber binding is significantly improved and the fiber bundling is significantly reduced, thin paper with uniform fiber dispersion can be obtained. Among these, the combination of fibers made of polycondensation polymers, fibers made of vinyl polymers, and/or fibers made of olefin polymers has a remarkable effect, especially when polyester fibers and vinylon fibers are mixed. The effect of finely and uniformly dispersing the fibers is remarkable. For example, the average pore area [Here, as an index of fiber dispersion, an image analysis device (manufactured by Nippon Avionics Co., Ltd., SP
Average pore area measured using ICCA-II):
It is the average value of the area of each void surrounded by tissue paper fibers when viewed in a plane, and the smaller the value, the more
It can be judged that the fibers are finely and uniformly dispersed." ] In other words, Ecuadorian hemp is 80% natural fiber.
When mixed in terms of weight percent, the average pore area of each is written in the order of 0.4 denier 3 mm polyester fiber mixed thin paper, 0.3 denier 3 mm vinylon fiber mixed thin paper, and thin paper mixed 50:50 of both. However, about 1100 μm2, about 1250 μm2, about 750
μm2, and by mixing the two types, the fiber dispersion becomes extremely uniform.

[0011]Furthermore, printed matter made with base paper using this thin paper as a support requires less Bain ink than base paper made with other supports even at the same printing density; in other words, the fibers are evenly dispersed. Therefore, the film is also uniformly perforated, and the ink is uniformly distributed for printing. The fibers other than chemical fibers constituting the thin paper in the present invention are commonly used plant-based natural fibers. Preferably, natural bast fibers such as manila hemp having an average fiber diameter (average diameter measured by enlarging with a microscope) of 20 μm or less are preferable from the viewpoint of fiber dispersibility and prevention of clumping. Note that in order to improve the dispersibility of fibers in thin paper, it is more preferable to use a mixture of natural fibers having different average fiber diameters.

[0012] The types of chemical fibers used in the present invention are:
Generally known synthetic fibers, recycled fibers, and semi-synthetic fibers may be used. Specifically, synthetic fibers include fibers made of polycondensation polymers, vinyl polymers, olefin polymers, such as polyester, nylon, acrylic, vinylon, polypropylene, polyvinyl chloride, polyethylene, polyvinylidene chloride, polyurethane, etc. In addition, recycled fibers include rayon, cupro, polynosic, etc., and semi-synthetic fibers include acetate, triacetate,
Promix etc. are used. In general, a suitable combination is selected taking into account the dispersibility, rigidity, etc. of the fibers, but among these, fibers made of polycondensation polymers, fibers made of vinyl polymers, and/or fibers made of olefin polymers are selected. A combination of fibers made of polymers tends to be preferred, and particularly preferred is a mixture of two types of fibers, polyester fibers and vinylon fibers, with natural fibers.

[0013] The shape of the synthetic fiber used in the present invention is as follows:
It is necessary that the single yarn fineness is 1 denier or less and the fiber length is 15 mm or less. When the single yarn fineness exceeds 1 denier, uniform passage of ink tends to be hindered. Preferably 0
．． 01-0.8 denier, more preferably 0.05-0
．． 5 denier, particularly preferably 0.1 to 0.4 denier. Furthermore, if the fiber length exceeds 15 mm, the dispersion of the fibers tends to deteriorate, resulting in a decrease in image quality. Preferably it is 1 to 10 mm, more preferably 2 to 8 mm. In addition, in the present invention, not only the type of fiber type but also fibers of the same fiber type but different shapes are used, for example, fibers with a circular cross section and fibers with a shape other than circular are used, and if the effect is obtained, the shape can also be changed depending on the type. It can be considered.

[0014]Furthermore, the chemical fiber is contained in the tissue paper in an amount of 20 to 80%.
It is necessary to contain it by weight%. Chemical fiber content is 20% by weight
If it is less than that, the effect on uniform fiber dispersion of natural fibers will be small, fibers will tend to bundle more, and image quality will tend to deteriorate. In addition, if the amount of synthetic fiber exceeds 80% by weight, the stiffness of the thin paper is low, so it lacks stiffness as a base paper, tends to cause problems in conveyance, and tends to cause large thermal deformation during plate making. Its use is restricted. Preferably it is 20 to 70% by weight, more preferably 30 to 60% by weight.

[0015] Furthermore, the ratio of two or more types of chemical fibers to be mixed together varies depending on the type of fibers used and the fineness of the single filament, so it can be arbitrarily selected within the range that produces the effect of the mixture. In the present invention, the thin paper after resin processing has a basis weight of 5 to 15
g/m2, thickness 10-50μm (JIS P-81
18). Basis weight is 5g/m2
If the thickness is less than 10μm or the thickness is less than 10 μm, the printing durability (the number of sheets that can be printed with one plate, and in this invention, the printing durability is 5.
000 sheets as the minimum), which is not preferable because it tends to decrease significantly. Further, those having a basis weight of more than 15 g/m2 and those having a thickness of more than 50 μm are not preferable because the passage of ink is severely restricted. Preferably, the basis weight is 8 to 13.5 g/m2, the thickness is 25 to 40 μm, and the density (basis weight ÷ thickness) is 0.25 to 0.40 g.
/cm2, and those within this range have very excellent image quality.

[0016] The thin paper according to the present invention is produced by a commonly used method. At this time, a dispersant, a sticky agent, an antifoaming agent, a release agent, a paper strength enhancer, a sizing agent, an antistatic agent, etc. may be added. In the present invention, the thin paper needs to contain at least 3 g/m2 of at least one type of urethane resin or epoxy resin on the surface of the fibers and in the intertwined portions of the fibers. This is necessary because when the affinity between natural fibers and chemical fibers (the degree of entanglement between the fiber surfaces) is low, the fibers tend to fall off from the thin paper, and the thin paper tends to stretch easily during printing. It is something. The amount of resin is 3
If it exceeds g/m2, a large number of resin films are formed at the openings of the thin paper, which tends to significantly impede the passage of ink, and thus image quality tends to deteriorate. Preferably 0.3~
2.0g/m2, more preferably 0.5-1.5g/m2
m2.

The urethane resins and epoxy resins used in the present invention include those of solvent solution type and those of water dispersion type (emulsion type). Also, non-reactive ones,
Reactive products (in the case of one-liquid type or two-liquid type, the reaction is carried out in combination with a crosslinking agent, crosslinking accelerator, etc.)
It may be any one of these, and can be appropriately selected depending on the fiber used.

[0018] For resin processing of thin paper, it is preferable to impregnate the thin paper with a solution or emulsion of urethane or epoxy resin or apply it with a gravure roll, and then dry it with a hot air dryer or a hot roll. A suitable drying temperature is 50 to 210°C. Furthermore, the paper strength can be further improved by applying heat-pressing processing using a hot roll at the same time as drying.

In resin processing, it is necessary to pay special attention to the resin concentration. Although it varies somewhat depending on the basis weight of the thin paper and the type of resin, a solution with a concentration of 7 to 30% is preferable. In resin processing, paper strength enhancers, sizing agents, etc. that are generally used in paper making may be used in combination. In order to obtain the base paper, the film to be laminated with the thin paper of the present invention is made of a thermoplastic polymer, has a thickness of 0.5 to 4 μm, and has a crystallinity of 30%.
The following stretched films are preferred. In addition, the heat shrinkage rate (X, %) of the stretched film at 100°C, 1
Heat shrinkage stress (Y, g/mm2) at 00°C is within the following formula: 15≦X≦80, 75≦Y≦500, and the relationship between the two is -10X+600≦Y≦-10
It is particularly preferable to be within the range of X+1000.

This film has higher plate-making sensitivity than conventional films for base paper, so less energy is required for plate-making, and it is easy to evenly disperse the film residue after plate-making into the thin paper fibers, making it suitable for use in thin paper. It has the characteristic of suppressing heat shrinkage during plate making of synthetic fibers. The physical property values of the film are determined by the following method.

The crystallinity of the film sample was determined using a DSC-2 model manufactured by PERKIN ELMER. The measurement was carried out at a heating rate of 10°C/min, and the crystal melting energy (ΔH) was determined from the measured area at the time of melting, and ΔH
It was determined from the ratio (ΔH/ΔHm) of the heat of fusion (ΔHm) of the crystal component described in the Chemical Handbook Applied Edition (revised 2nd edition). However, if ΔHm was unknown for the copolymer, ΔHm of the main repeating unit was used.

Heat shrinkage rate is determined by leaving a 50 mm square film sample in a 100°C hot air circulation constant temperature bath for 10 minutes in a state where it freely shrinks, then calculating the amount of film shrinkage, and dividing the value by the original dimension. It was expressed as a percentage, and the average value in the vertical and horizontal directions was used. Heat shrinkage stress was determined by sampling the film into a strip with a width of 10 mm, setting it between 50 mm between chucks with strain gauges, and immersing it in silicone oil heated to 100°C.
The value after 0 seconds was determined as the average value in the vertical and horizontal directions.

[0023] The reasons for limiting the required properties of the film will be described below. First, films with a thickness of less than 0.5 μm have weak film strength and are difficult to use in practice;
If it exceeds the above, the required plate-making energy will be high and the object of the present invention will not be satisfied. Therefore, the appropriate thickness of the film is 0.5 to 4 μm, preferably 0.8 to 3 μm.
μm, more preferably 1 to 2.5 μm.

Next, the smaller the crystallinity, the higher the plate-making sensitivity tends to be, and the crystallinity needs to be 30% or less. Preferably it is 20% or less, more preferably 10% or less. The thermoplastic resin film used in the present invention is
Conventionally known materials can be used, and for example, films made of resins such as polyester, nylon, polyethylene, polypropylene, polyvinylidene chloride, polyvinyl chloride, polyvinylidene fluoride, and copolymer resins thereof are suitable. Further, these resins may be used in a blended manner as long as the film forming properties are not deteriorated. Considering the characteristics of heat-sensitive perforation of base paper, that is, when the film is heated in accordance with characters and figures, the predetermined areas melt and the balance of shrinkage rate and shrinkage rate is considered. preferable. Further, a resin copolymerized with a polyethylene terephthalate component is preferred, and among these, an amorphous polyester film is particularly preferred. Specifically, the crystallinity of the raw material resin that has been sufficiently annealed to reach an equilibrium state (by wide-angle X-ray method: Rotaflex RU-20 manufactured by Rigaku Denki Co., Ltd.)
At 0B, using a graphite monochromator, applied voltage 50 kV, applied current 160 mA, target Cu,
It is a substantially amorphous material having a measurement angle 2θ=5 to 38°) of 20% or less, more preferably 10% or less, particularly preferably 5% or less. This particularly preferred resin was copolymerized using a resin mainly composed of terephthalic acid as the dicarboxylic acid component and a mixture of about 70 mol% ethylene glycol and about 30 mol% 1,4-cyclohexanedimethanol as the diol component. There are amorphous polyester resins.

Furthermore, the heat shrinkage rate at 100°C (X, %
) and heat shrinkage stress (Y, g/mm2) are 15≦X
It is necessary that the relationship is within the range of ≦80, 75≦Y≦500, and the relationship between the two is within the range of -10X+600≦Y≦-10X+1000. X<15 or Y<75, Y<-
Those in the 10X+600 range tend to have low platemaking sensitivity and are therefore difficult to use in the present invention. Also, X>80 and Y>75, or X>15 and Y>500, Y
Those in the range >-10X+1000 have poor dimensional stability and tend to curl easily when used as base paper, and are therefore limited. Preferably, 30≦X≦70 and 150≦Y≦
400, -10X+600≦Y≦-10X+1000,
More preferably, 45≦X≦65 and 200≦Y≦3
The range is 50.

[0026] Furthermore, other polymers and oligomers can be added to the film within a range that does not impair the necessary properties, and various additives such as antioxidants,
Heat stabilizers, plasticizers, lubricants, etc. can be added depending on the purpose. Films are made using T-die method, circular die method,
Known molding techniques such as dry or wet casting are applied. During film forming, a plasticizer may be added depending on the polymer material. In addition, fillers such as silica and talc may be added to improve the winding properties during molding. When stretching the film, a known stretching technique such as a tenter method or an inflation method is applied to form the film so that it has the heat shrinkage characteristics described above. The stretching ratio when stretching the film is appropriately determined in consideration of the characteristics of the resin used and the thermal perforation characteristics of the base paper. In addition, if it is difficult to handle a thin film, it is possible to use the desired film by laminating and stretching the desired film and another film, and then peeling it off. It is also possible to peel off the other tanks after laminating and adhering the target film.

[0027] Furthermore, the thin paper of the present invention and the film can be bonded together using an adhesive under conditions that do not impede ink permeability and perforation suitability of the film. As the adhesive, various commonly known adhesives such as solvent type, hot melt type, emulsion latex type, reaction curing type, ultraviolet ray and electron beam curing type are used. In addition, the method of adhesion is
They may be bonded together by applying an adhesive to the thin paper side, the film side, or both, using a commonly known method. The amount of adhesive is 0.1 to 5 g/m2, preferably 0.1 to 5 g/m2.
5-3g/m2, more preferably 0.5-2g/m2
It is.

[0028] Furthermore, a release agent for preventing stickiness may be applied to the film surface of the base paper before or after lamination with thin paper, if necessary. A known silicone-based or fluorine-based release agent is used, and the amount of application is appropriately determined depending on the type of release agent and the thermal perforation sensitivity of the base paper.

[0029]

EXAMPLES The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to these Examples. The composition ratio of the thin paper is shown in Table 1, and the resin processing and base paper performance evaluation results are shown in Table 2.

Furthermore, each performance of the base paper was evaluated according to the following method. (1) Evaluation of image quality Printing device for thermal head test [manufactured by Okura Electric Co., Ltd., thermal coloring device TH-P
MD] is equipped with a thermal head [manufactured by Toshiba Corporation, TPH256R8D] with a heating element density of 400 dots/inch, and it prints 2 mm square fine characters, thin lines formed by 1 and 2 dots, and 50 mm square black. Optimum plate-making sensitivity for a pattern that can print solid areas [manufactured by Dainippon Screen Mfg. Co., Ltd., DM-800, with the minimum plate-making energy at which the printing density of black solid areas is 1.10 ± 0.05. The plate was made under the following conditions. Furthermore, the base paper after plate making is printed on a fully automatic digital stencil printing machine [manufactured by Riso Kagaku Kogyo Co., Ltd., RC].
-115] was evaluated with the naked eye. ○ indicates that there are no uneven thickness of letters or thin lines or white spots in solid black areas; Those marked △ are considered to be somewhere in the middle, and are at a level that can be used for practical purposes. (2) Evaluation of printing durability: If the image on the first printed sheet is not distorted even if more than 5,000 sheets are printed at a printing speed of 130 sheets/min using the above-mentioned printing machine, ○, 50
If the image was distorted after printing less than 00 sheets, it was rated as "×".

[0031]

[Example 1] (Manufacture of thin paper) Manila hemp was digested with alkali, washed with water, diluted with water to a concentration of 3%, and beaten with a beater to a freeness of 18°SR (JIS P-8121).40 weight %, similar to sisal, freeness 25°
Beaten to SR 20% by weight, 0.1 denier, 3m
20% by weight of PET fiber, 0.3 denier, 3 mm
20% by weight of vinylon fibers are mixed uniformly, and then epoxidized polyamide resin is added to the fibers at
% in an aqueous solution and mixed uniformly. This was used as paper stock to obtain thin paper before resin processing using a wet paper making method using a cylinder paper machine. Furthermore, this thin paper was coated with a water-based emulsion type urethane resin [Superflex 10, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.] using a gravure coating machine.
0] at a coating amount of 0.8 g/m2,
A thin paper having a basis weight of 10.5 g/m 2 and a thickness of 31.6 μm was obtained and used as a base paper support. (Production of heat-sensitive film) The heat-sensitive layer was prepared from terephthalic acid and a mixed diol consisting of 30 mol% of 1,4-cyclohexanedimethanol and 70 mol% of ethylene glycol, with a Vicat softening point of 82°C and a density of 1.27 g.
/cm3, a substantially amorphous copolyester with an intrinsic viscosity of 0.75 was used, and as a release layer, an oleic acid ester release agent was contained in a composition mainly composed of ethylene-vinyl acetate copolymer. The mixtures were melted in an extruder and extruded through an annular multilayer die so that heat-sensitive layers were formed on both sides of the release layer. Thereafter, the multilayer film was wound up after simultaneous biaxial stretching in a bubble shape so that the stretching ratio was 5 times in the vertical direction and 5 times in the horizontal direction. The thickness of each layer of this multilayer film is: heat-sensitive layer/release layer/heat-sensitive layer: 2/12/2μ
m, the crystallinity of this heat-sensitive film is 6%, and 10
Heat shrinkage rate at 0℃ is 59%, heat shrinkage stress is 275g
/m2, and this multilayer film was used to prepare base paper. (Manufacture of adhesive) Ethylene glycol diglycidyl ether as an epoxy compound (Nagase Kasei Kogyo Co., Ltd., Denacol EX-810), polyamide amine as a polyamine resin [Sanwa Kagaku Kogyo Co., Ltd., Sanmide 300]
Using , the weight ratio of epoxy compound: polyamine resin =
An adhesive solution was prepared by dissolving it in isopropyl alcohol so that the ratio was 17:83. (Manufacture of base paper) Using a gravure coater, apply an adhesive solution adjusted to have a solid content coating amount of 1.0 g/m2 on the above-mentioned thin paper as a support, and overlap it with the above-mentioned multilayer film. The stacked product was passed through a drying oven set at 50° C. to evaporate the solvent and then wound up. Further, in the same manner, thin paper was laminated on the back side to obtain a base paper intermediate with thin paper formed on both sides. Furthermore, this base paper intermediate was added to 35
After aging at 48 hours to complete adhesion, the base paper and release layer were peeled off. Using the obtained base paper, 0.05 g/m2 of silicone oil was coated on the film surface to form an overcoat layer for preventing heat fusion, to obtain a final base paper.

[0032] The image quality of the printed matter printed with this base paper is that even fine lines are printed clearly, and there are few white spots in solid black areas, and the evaluation is ○, and the printing durability can be printed for 5000 sheets, and the evaluation is ○.
The result was that I was satisfied with everything.

[0033]

[Example 2] The ratio of fiber composition in each weight ratio: Manila hemp:
0.4 denier 3mm PET fiber: 0.3 denier 3m
1.0 g/m2 of the same resin as in Example 1 was applied to thin paper made with m-vinylon fibers = 60:20:20 and processed with resin, resulting in a basis weight of 10.4 g/m2 and a thickness of 34.9μ.
m thin paper was obtained. Using this thin paper and the film used in Example 1, a base paper was prepared in the same manner as in Example 1. The performance of this base paper was very good as in Example 1.

[0034]

[Example 3] Using the same resin as the film resin used in Example 1, the same manufacturing method was used with different heat treatment conditions.
Heat shrinkage rate at 0℃ is 42%, heat shrinkage stress is 185
A film of g/mm2 was obtained. Using a multilayer film with this film formed on both sides, a base paper was prepared using the same thin paper as in Example 1 and in the same manner. This base paper also had good performance.

[0035]

[Example 4] The ratio of fiber composition in each weight ratio: Manila hemp:
0.1 denier 3mm PET fiber: 0.3 denier 3m
m Vinylon fiber: 0.4 denier 3mm nylon fiber =
0.9 g/m2 of the same resin as in Example 1 was applied to a thin paper made with a ratio of 60:20:10:10, and resin-processed to obtain a thin paper having a basis weight of 10.1 g/m2 and a thickness of 34.4 μm. Using this thin paper and the film used in Example 1, a base paper was prepared in the same manner as in Example 1. This base paper also had good performance.

[0036]

[Example 5] The ratio of fiber composition in each weight ratio: Manila hemp:
0.4 denier 3mm PET fiber: 0.3 denier 3m
A solvent-based epoxy resin [Takashi Kubo Paint (
Co., Ltd., Sunfirst E Clear Enamel] 0.7
g/m2 Coated and resin processed, basis weight 10.8g/m2
, a thin paper with a thickness of 32.5 μm was obtained. Using this thin paper and the film used in Example 1, a base paper was prepared in the same manner as in Example 1. This base paper also had good performance.

[0037]

[Comparative Example 1] Same film as Example 1 and Manila hemp 10
0% thin paper (basis weight = 10.0 g/m2, thickness = 31
．． A base paper was prepared in the same manner as in Example 1, using 2 μm). Regarding the image quality of this base paper, there were many white spots in solid black areas. This is because natural fibers alone have poor fiber dispersibility and many fiber bundles. Although this thin paper was not resin-treated, there was no problem with printing durability since it was made of natural fibers.

[0038]

[Comparative Example 2] The ratio of fiber composition in each weight ratio is Manila hemp:
0.9 g/m2 of the same resin as in Example 1 was added to thin paper made with 0.4 denier 3 mm PET fiber = 60:40.
It was coated and processed with a resin to obtain thin paper having a basis weight of 10.5 g/m2 and a thickness of 35.4 μm. Using this thin paper and the film used in Example 1, a base paper was prepared in the same manner as in Example 1. Compared to the base paper of Example 1, this base paper had noticeable white spots in solid black areas.

[0039]

[Comparative Example 3] The ratio of fiber composition in each weight ratio is Manila hemp:
0.8 g/m of the same resin as in Example 1 was added to thin paper made with 0.3 denier 3 mm vinylon fiber = 70.30.
2 and processed with resin to obtain thin paper having a basis weight of 9.6 g/m2 and a thickness of 31.9 μm. Using this thin paper and the film used in Example 1, a base paper was prepared in the same manner as in Example 1. Compared to the base paper of Example 1, this base paper also had noticeable white spots in solid black areas.

[0040]

[Comparative Example 4] The same film as in Example 1 and thin paper with the same fiber composition but without resin treatment (basis weight: 1
0.2 g/m2, thickness: 30.5 μm), a base paper was prepared in the same manner as in Example 1. Although this base paper has good plate-making sensitivity and image quality, its printing durability is 2500.
It was defective. This is thought to be because the thin paper is not resin-treated, so the intertwined portions of the fibers cannot withstand the force generated during printing, and the thin paper stretches, causing the image to become distorted.

[0041]

[Table 1]

[0042]

[Table 2]

[0043]

[Effect of the invention] The thin paper of the present invention has good fiber dispersibility.
Since it is a thin paper made by mixing two or more types of chemical fibers with a fineness of 1 denier or less and natural fibers, the average fiber diameter is small and the fiber dispersibility is more uniform. Therefore, printed matter obtained by stencil printing of base paper using this thin paper as a support has extremely high image quality. Furthermore, since the fiber surface of the support and the intertwined portions of the fibers are treated with resin, the elongation of the base paper during high-speed multi-sheet printing is suppressed, resulting in excellent printing durability.

Claims (1)

[Claims] Claim 1: Thin paper with a basis weight of 5 to 15 g/m2 and a thickness of 10 to 50 μm, containing 20 to 80% by weight of two or more types of chemical fibers with a single filament fineness of 1 denier or less and a fiber length of 15 mm or less, 3g/ on the fiber surface and the intertwined part of the fiber
A porous thin paper characterized by containing a synthetic resin of m2 or less.