JP2006281690A - Tissue paper for stencil printing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide tissue paper for stencil printing, which is thin, homogeneous, excellent in printing resistance, and suitable for both an oil-based ink and a water-based ink. <P>SOLUTION: This tissue paper for stencil printing contains: at least either of two kinds of fibrillated fibers, that is, a fibrillated fiber (X) with a fiber diameter of 1 μm or less, separated from a stem part, or a fibrillated fiber (Y), where a branch part with a fiber diameter of 1 μm or less is developed from the stem part of with a fiber diameter of 2 μm or more; and an organic fiber (Z) with a fiber diameter of 1-30 μm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a thin paper for stencil printing which is perforated and made by a flash irradiation such as a halogen lamp, a xenon lamp or a flash bulb, an infrared irradiation, a pulse irradiation such as a laser beam, or a thermal head.

  As a simple printing method, a stencil printing method is widely used. As the stencil base paper, a laminate in which a thermoplastic film layer or a heat-sensitive stencil layer composed of a thermoplastic polymer coating layer is laminated on a porous support is used. This stencil printing base paper forms image-like perforations by flash irradiation, infrared irradiation, pulse irradiation of laser beams, etc., and thermal printing with a thermal head. The printing ink is supplied from and printing is performed on a substrate such as paper.

  As the porous support, a thin paper made of natural fiber or synthetic fiber alone or mixed paper is generally used. When such a stencil thin paper is used as a support, in the dense part of the stencil thin paper, the passage of ink is hindered, white spots occur, printing unevenness occurs, and stencil printing The smoothness of the thermoplastic film surface decreases due to the fiber texture of the thin paper for use.For example, when forming image-like perforations by thermal printing with a thermal head, the adhesion with the thermal head is reduced and unperforated portions are formed. There was a problem of printing unevenness.

  In order to solve these problems, thin stencil paper for stencil printing that is thin, homogeneous and excellent in printing durability is required. For example, a thin paper for stencil printing that includes polyester and / or acrylic ultrafine fibers of 0.1 dtex or less has been proposed. In this thin paper for stencil printing, even the thinnest fibers are 0.1 dtex, that is, about 3 μm, so that white spots and smoothness are low, printing unevenness occurs, and high resolution images cannot be handled. There is a problem (for example, Patent Document 1).

As an example using finer fibers, stencil printing thin paper composed of fibrillated cellulose fibers as at least a part of main fibers has been proposed. In this thin paper for stencil printing, in order to improve printing durability, 0.4 dtex or less polyvinyl alcohol fiber is added as a main fiber, and fibrous polyvinyl alcohol is used as a binder. Utilizing hydrogen bonds formed between the polyvinyl alcohol fiber and the polyvinyl alcohol binder, the mechanical strength of the stencil thin paper is increased. However, due to recent environmental problems, stencil printing systems are also required to use water-based inks instead of oil-based inks. In thin paper for stencil printing using such hydrogen bonds, printing is required. The mechanical strength sometimes decreased (for example, Patent Document 2).
JP-A-3-8892 Japanese Patent Laid-Open No. 6-155556

  An object of the present invention is to provide a thin paper for stencil printing which is thin, homogeneous and excellent in printing durability and is suitable for both oil-based ink and water-based ink.

As a result of intensive studies to solve the above problems, the present inventors have found the following invention. That is,
(1) (X) Two types of fibrillated fibers: a fibrillated fiber having a fiber diameter of 1 μm or less detached from the trunk, and (Y) a fibrillated fiber having a branch having a fiber diameter of 1 μm or less generated from a trunk having a fiber diameter of 2 μm or more. A thin paper for stencil printing comprising (Z) an organic fiber having a fiber diameter of 1 to 30 μm,
(2) The fibrillated fibers (X) and (Y) are at least one selected from fibrillated lyocell fibers, fibrillated acrylic fibers, and fibrillated aromatic polyamide fibers. Thin paper for stencil printing,
(3) The thin paper for stencil printing as described in (1) or (2) above, wherein at least a part of the organic fiber (Z) is a heat-fusible binder fiber,
(4) The stencil printing thin paper according to any one of (1) to (3) above, wherein the organic fiber (Z) is a polyester fiber,
(5) The total content of (X) and (Y) is 1 to 98% by mass and the content of (Z) is 2 to 99% by mass with respect to the stencil thin paper. The thin paper for stencil printing according to any one of (1) to (4) above.

  The fibrillated fibers used in the stencil sheet of the present invention are much finer than conventionally used fibrillated fibers and are therefore suitable for producing thin stencil sheets. However, when only the fibrillated fibers are used, the fibrillated fibers may fall off during production or the fibrillated fibers may aggregate. In particular, the fibrillated fiber (Y) in which the branch portion is generated from the trunk portion is easily entangled due to its specific structure. Therefore, (Z) Organic fibers with a fiber diameter of 1 to 30 μm are used in combination, and a uniform structure in which fibrillated fibers are entangled with a network made of thick organic fibers (Z) is formed, so that fibrillated fibers are present uniformly. However, it can be a thin, high-strength stencil sheet. In the present invention, since the network formed by the organic fiber (Z) has both water resistance and solvent resistance, it becomes a stencil thin paper suitable for both water-based ink and oil-based ink.

  In the thin paper for stencil printing of the present invention, fibrillation refers to a phenomenon in which fibrils (small fibers) inside the fibers appear on the surface by friction and become fluffy. In the present invention, the fiber (X) fibrillated to a fiber diameter of 1 μm or less detached from the trunk and the fibrillated fiber (Y) having a branch diameter of 1 μm or less from the trunk having a fiber diameter of 2 μm or more are generated. Use different fibers.

  The fibrillated fiber related to the thin paper for stencil printing of the present invention is not particularly limited as long as it can be fibrillated. Acrylic, acrylic, lyocell, pulp, rayon, wholly aromatic polyamide, wholly aromatic polyester, wholly aromatic polyester amide, wholly aromatic polyether, wholly aromatic polycarbonate, wholly aromatic polyazomethine, polyphenylene sulfide (PPS), Poly-p-phenylenebenzobisthiazole (PBZT), polybenzimidazole (PBI), polyetheretherketone (PEEK), polyamideimide (PAI), polyimide, polytetrafluoroethylene (PTFE), poly-p-phenylene-2 Fibers such as 1,6-benzobisoxazole (PBO) can be used.

  Among these, those that can be easily fibrillated include acrylic fiber or lyocell fiber. It is particularly preferable to use split fiber acrylic fibers. The split fiber acrylic fiber is a fiber that can be split by subjecting the spun acrylic fiber to post-treatment such as heat treatment, chemical treatment, and mechanical treatment. In the present invention, the split fiber is treated by fibrillation described later. Use possible acrylic fibers. It may be comprised only from the acrylonitrile type polymer used for a normal acrylic fiber, and may be comprised from an acrylonitrile type polymer and an additive polymer.

  The copolymerization component of acrylonitrile is not particularly limited as long as it is a copolymerization monomer constituting an ordinary acrylic fiber, and examples thereof include the following monomers. That is, acrylic esters represented by methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate And unsaturated monomers such as acrylic acid esters, acrylic acid, methacrylic acid, maleic acid, acrylamide, styrene, vinyl toluene, vinyl acetate, vinyl chloride, vinylidene chloride, and vinylidene fluoride.

  The additive polymer is not particularly limited, and examples thereof include acrylic resin-based polymers and some polymers. Although the monomer which comprises an acrylic resin polymer is not specifically limited, For example, the following monomers are mentioned, Among these, 1 or more types can be used. That is, acrylic acid esters represented by methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate Methacrylic acid esters such as acrylic acid, methacrylic acid, maleic acid, acrylamide, styrene, vinyl toluene, vinyl acetate, vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, etc. It is. Examples of the polymer other than the acrylic resin polymer include polyvinyl chloride, polyalkylene glycol, polyether compound, polyether ester compound, cellulose acetate, polysulfone, polyvinyl alcohol, polyamide, polyester, and polypeptide.

  When the softening point or glass transition point of the additive polymer used in the split fiber acrylic fiber is lower than the processing temperature in the process of producing stencil thin paper, it takes a temperature above the softening point or glass transition point, Part or all of the additive polymer may melt and form a film over the fibrillated fibers (X), (Y) on the surface of the stencil sheet. In that case, there is a possibility of causing uneven printing. Therefore, the additive polymer having a relatively high softening point or glass transition point is selected, or the process temperature in the temperature-sensitive process, for example, the drying process or the heat-treatment process, is made in the manufacture of stencil thin paper. It is preferable to carry out at a temperature lower than the softening point or glass transition point.

  Lyocell is a fiber term defined by JIS and ISO standards. “Cellulose fiber obtained by organic solvent spinning method. Organic solvent means a mixed solution of organic compound and water. Solvent spinning method means cellulose. It refers to a method of spinning by directly dissolving without using a derivative. " The lyocell fiber has advantages such as excellent wet strength, easy fibrillation, and formation of hydrogen bonds peculiar to cellulose fibers, so that the mechanical strength of stencil thin paper can be increased. In addition, lyocell fiber has a property that it slightly swells with water, plays a role of a cushion, and effectively acts to improve printing durability.

  When heat resistance is required for thin paper for stencil printing, it is preferable to use a wholly aromatic polyamide or wholly aromatic polyester that is easily fibrillated due to liquid crystallinity as the fibrillated fiber.

  It is important to find the optimum fibrillation conditions in order to develop the properties such as uniformity, thin film properties, and mechanical strength of the stencil sheet. A fibrillated fiber (X) having a fiber diameter of 1 μm or less released from the trunk by applying a shearing force, and a fibrillated fiber having a branch having a fiber diameter of 1 μm or less generated from the trunk having a fiber diameter of 2 μm or more by applying a shearing force The two fibers having a degree of fibrillation (Y) can be obtained by appropriately adjusting the conditions (apparatus, concentration, temperature, time, stress, additive, etc.) of the fibrillation step. The degree of fibrillation of the fibrillated fibers can be confirmed by sufficiently diluting the fibrillated fibers with water or the like and then drying and observing with a microscope or preferably an electron microscope.

  The fibrillated fiber according to the present invention is fibrillated by a beater, a PFI mill, a single disc refiner (SDR), a double disc refiner (DDR), or a beating or dispersing equipment such as a ball mill or a dyno mill used for dispersing or grinding pigments. Is done.

  There is no particular limitation on the cross-sectional shape of the fiber for preparing the fibrillated fiber for the stencil sheet of the present invention, not only circular, elliptical, flat, triangular, Y-type, T-type, U-type, star-type, It may be a dog-bone type having a so-called irregular cross-sectional shape, a hollow shape, or a branched shape. In the fibrillation step, a circular or elliptical shape is most preferable because it is difficult to aggregate. In addition, the cross-sectional shape of the fiber after fibrillation is not particularly limited, but examples thereof include not only circular and elliptical shapes but also flat cross-sectional shapes such as flat, streaked, American characters, and triangles.

  In the thin paper for stencil printing of the present invention, (X) the aspect ratio (fiber length / fiber diameter) of the fibrillated fiber having a fiber diameter of 1 μm or less detached from the trunk is 10 to 100,000, more preferably 100 to 50,000. . Moreover, (Y) In the fibrillated fiber in which the branch portion is generated from the trunk portion, the aspect ratio of the trunk portion is 10 to 50000, preferably 50 to 30000. Further, the aspect ratio of the branch portion is 10 to 100,000, preferably 100 to 50,000. These fibrillation states can be confirmed by microscopic observation as described above.

  In the thin paper for stencil printing of the present invention, (Z) organic fibers having a fiber diameter of 1 to 30 μm include polyester fibers such as polyethylene terephthalate, polybutylene terephthalate, and copolymers thereof, and polyolefin fibers such as polyethylene, polypropylene, and polystyrene. Synthetic fibers such as fibers, acrylic fibers such as polyacrylonitrile, acrylic fibers such as modacrylic, polyamide fibers such as nylon 6, nylon 66, and nylon 12, polyvinyl alcohol fibers, polyvinylidene chloride fibers, polyvinyl chloride fibers, urethane fibers Solution of semi-synthetic fibers such as triacetate fiber and diacetate fiber, regenerated cellulosic fibers such as viscose rayon, copper ammonia rayon, polynosic rayon, lyocell, collagen, alginic acid, chitin Regenerated fibers that were spun those can be mentioned. The polymers constituting these fibers can also be used in the form of homopolymers, modified polymers, blends, copolymers and the like. In addition to the above-mentioned fibers, wood fibers such as softwood pulp, hardwood pulp, wood pulp such as straw pulp, bamboo pulp, kenaf pulp, and herbs can be used as plant fibers. Furthermore, pulp fibers obtained from waste paper, waste paper, and the like are also included. Of course, a composite fiber made of a plurality of these materials may be used. Also, the cross-sectional shape is not only circular or elliptical, but also flat, triangular, Y-shaped, T-shaped, U-shaped, star-shaped, dog-bone shaped, etc. It may be a thing.

  In the thin paper for stencil printing of the present invention, the organic fiber (Z) having a fiber diameter of 1 to 30 μm may be a heat-fusible binder fiber. The mechanical strength of the stencil printing thin paper is improved by including a heat-fusible binder fiber and incorporating a heat treatment at a temperature higher than the melting temperature of the binder fiber into the manufacturing process. In particular, even when water-based ink is used, high mechanical strength can be exhibited. Examples of the heat-fusible binder fiber include single fibers, and composite fibers such as core-sheath fibers (core-shell type) and parallel fibers (side-by-side type). Since the composite fiber hardly forms a film on the surface of the stencil printing thin paper, the mechanical strength can be improved while the fibrillated fiber on the surface of the stencil printing thin paper is kept exposed. Examples of heat-fusible binder fibers include a combination of polypropylene (core) and polyethylene (sheath), a combination of polypropylene (core) and ethylene vinyl alcohol (sheath), a high-melting polyester (core) and a low-melting polyester (sheath). The combination of is mentioned. In addition, single fibers composed of only low-melting resins such as polyethylene (full melt type) and hot water-soluble binders such as polyvinyl alcohol are easy to form a film in the drying process of manufacturing stencil paper. Since it may interfere with the transmission of ink and cause uneven printing, it can be used as long as it does not form a film.

  In the thin paper for stencil printing of the present invention, a thermoplastic resin can be contained in order to further improve mechanical strength and resistance to printing ink, that is, water resistance and oil resistance. Examples of the thermoplastic resin include latexes such as acrylic, vinyl acetate, epoxy, synthetic rubber, urethane, polyester, and vinylidene chloride, polyvinyl alcohol, starch, phenol resin, and the like. Or two or more types can be used in combination. Among these, latexes such as epoxy, synthetic rubber, urethane, polyester, and vinylidene chloride are preferable for improving water resistance.

  The amount of the thermoplastic resin contained in the stencil thin paper of the present invention is suitably 0.01 to 10% by mass relative to the stencil thin paper. If it exceeds 10% by mass, the fiber network of the stencil thin paper will be blocked. On the other hand, when the content is less than 0.01% by mass, mechanical strength and water resistance are not improved as compared with a stencil sheet containing no thermoplastic resin.

  The method of incorporating the thermoplastic resin into the stencil sheet is not particularly limited, and examples thereof include a size press method, a tab size press method, a spray method, an internal addition method, and a gravure coating method.

  In the stencil sheet of the present invention, additives such as a crosslinking agent, a water repellent, a dispersant, a yield improver, a paper strength agent, and a dye are added to the stencil sheet as necessary. It can mix | blend suitably.

  The thin paper for stencil printing of the present invention is produced by a step of fibrillating fibrillated fibers, a step of paper making a thin paper for stencil printing, and a step of removing (drying) moisture. In order to fuse the heat-fusible binder fiber, a drying step may be further provided. In the paper making process of the present invention, fibrillated fibers and organic fibers are put into water, mixed by a rotary apparatus such as a pulper, dispersed, and a fiber suspension having a concentration of about 0.1 to 3% by mass. Prepare the solution. Next, the suspension is used to make a paper using a paper machine having at least one wire such as a long mesh, a short mesh, a circular mesh, or an inclined wire. In the drying process, an air dryer, a cylinder dryer, a suction drum dryer, an infrared dryer, or the like can be used. The same dryer can also be used in the step of fusing the heat-fusible binder fiber or the drying step after impregnating the thermoplastic resin.

Hereinafter, the present invention will be described in detail by way of examples.
<Preparation of fibrillated fiber>
A non-fibrillated lyocell monofilament (1.7 dtex × 4 mm) made by Lenzing was repeatedly processed 15 times using a double disc refiner to prepare a fibrillated lyocell fiber (X1) having an average fiber diameter of 0.9 μm detached from the trunk. did.

<Preparation of fibrillated fiber>
A fibrillated lyocell in which a non-fibrillated lyocell monofilament (1.7 dtex × 4 mm) made by Lenzing was repeatedly processed 40 times using a single disc refiner, and branches having an average fiber diameter of 1 μm or less were generated from a trunk having an average fiber diameter of 3 μm. A fiber (Y1) was prepared.

<Preparation of fibrillated fiber>
A fibrillated lyocell fiber (1.7 dtex × 4 mm), which is not fibrillated, is processed for 40,000 revolutions using a PFI mill, and a fibrillated lyocell fiber having a fiber diameter of 1 μm or less and a trunk part having an average fiber diameter of 4 μm. To prepare a mixed fiber (XY1) of fibrillated lyocell fibers in which branches having an average fiber diameter of 1 μm or less were generated.

<Preparation of fibrillated fiber>
Non-fibrillated lyocell lyocell (1.7 dtex × 4 mm) manufactured by Lenzing Co., Ltd. was subjected to 2000 rotation treatment using a PFI mill, and a fibrillated lyocell in which a branch part having an average fiber diameter of 2.5 μm was generated from a trunk part having an average fiber diameter of 5 μm. Fiber (V1) was prepared.

<Preparation of fibrillated fiber>
A non-fibrillar split fiber acrylic fiber (Bonnel MV PC 300, 3 dtex × 3 mm) manufactured by Mitsubishi Rayon Co., Ltd. was repeatedly treated 10 times using a double disc refiner, and an average fiber diameter of 0.9 μm detached from the trunk A fibrillated acrylic fiber (X2) was prepared.

<Preparation of fibrillated fiber>
Non-fibrillar split fiber acrylic fiber (Bonnel MV PC 300, 3 dtex × 3 mm) manufactured by Mitsubishi Rayon Co., Ltd. is treated 30 times using a single disc refiner, and the average fiber diameter is 1 μm or less from the trunk having an average fiber diameter of 3 μm. A fibrillated acrylic fiber (Y2) having a branched portion was prepared.

<Preparation of fibrillated fiber>
Non-fibrillated split fiber acrylic fiber manufactured by Mitsubishi Rayon Co., Ltd. (Bonnell M.V.P C300, 3 dtex × 3 mm) is processed 10,000 times using a PFI mill, and the fiber diameter is 1 μm or less detached from the trunk. A mixed fiber (XY2) of fibers and a fibrillated acrylic fiber in which branches having an average fiber diameter of 1 μm or less were generated from a trunk part having an average fiber diameter of 3 μm was prepared.

<Preparation of fibrillated fiber>
A non-fibrillar split fiber acrylic fiber (Bonnel M.V.P C300, 3 dtex × 3 mm) manufactured by Mitsubishi Rayon Co., Ltd. was subjected to 1000 rotation treatment using a PFI mill, and an average fiber diameter of 2.5 μm from a trunk having an average fiber diameter of 5 μm. A fibrillated acrylic fiber (V2) in which the branch part was generated was prepared.

<Preparation of fibrillated fiber>
Para-type wholly aromatic polyamide fiber (Twaron 1080, 1.2 dtex × 3 mm) manufactured by Teijin Techno Products Ltd. was repeatedly treated 15 times using a double disc refiner, and fibrillated para with an average fiber diameter of 0.8 μm detached from the trunk. A fully aromatic polyamide fiber (X3) was prepared.

<Preparation of fibrillated fiber>
Para-type wholly aromatic polyamide fibers (Twaron 1080, 1.2 dtex × 3 mm) manufactured by Teijin Techno Products Ltd. were repeatedly treated 20 times using a single disc refiner, and branches having an average fiber diameter of 1 μm or less from the trunk part having an average fiber diameter of 4 μm. The generated fibrillated para-aromatic polyamide fiber (Y3) was prepared.

<Preparation of fibrillated fiber>
Para-type wholly aromatic polyamide fiber (Twaron 1080, 1.2dtex × 3mm) manufactured by Teijin Techno Products Ltd. was processed 15,000 rotations using a PFI mill, and the fibrillated para aromatic having a fiber diameter of 1 μm or less detached from the trunk. A mixed fiber (XY3) of polyamide fiber and a fibrillated para-aromatic polyamide fiber in which branches having an average fiber diameter of 1 μm or less were generated from a trunk part having an average fiber diameter of 3 μm was prepared.

<Preparation of fibrillated fiber>
Para-type wholly aromatic polyamide fiber (Twaron 1080, 1.2 dtex × 3 mm) manufactured by Teijin Techno Products Ltd. was repeatedly treated seven times using a single disc refiner, and branches having an average fiber diameter of 5 μm or less from the trunk portion having an average fiber diameter of 5 μm. The generated fibrillated para-aromatic polyamide fiber (V3) was prepared.

<Preparation of fibrillated fiber>
Kuraray's wholly aromatic polyester fiber (Vectran HHA, 1.7 dtex x 3 mm) was repeatedly treated 15 times using a double disc refiner, then treated 20 times using a high pressure homogenizer at 50 MPa, and detached from the trunk. A fibrillated wholly aromatic polyester fiber (X4) having an average fiber diameter of 0.7 μm was prepared.

<Preparation of fibrillated fiber>
Kuraray's wholly aromatic polyester fiber (Vectran HHA, 1.7 dtex × 3 mm) was repeatedly treated 22 times using a single disc refiner, and fibrillation was generated from a trunk having an average fiber diameter of 3 μm to a branch having an average fiber diameter of 1 μm or less. A wholly aromatic polyester fiber (Y4) was prepared.

<Preparation of fibrillated fiber>
Kuraray's wholly aromatic polyester fiber (Vectran HHA, 1.7 dtex × 3 mm) was processed for 15,000 revolutions using a PFI mill, and a fibrillated wholly aromatic polyester fiber having a fiber diameter of 1 μm or less detached from the trunk, A mixed fiber (XY4) of fibrillated wholly aromatic polyester fibers in which branches having an average fiber diameter of 1 μm or less were generated from a trunk part having an average fiber diameter of 3 μm was prepared.

<Preparation of fibrillated fiber>
Kuraray's wholly aromatic polyester fiber (Vectran HHA, 1.7 dtex x 3 mm) was repeatedly treated seven times using a single disc refiner, and fibrillation was generated from trunks having an average fiber diameter of 8 μm to branches having an average fiber diameter of 2 μm or less. A wholly aromatic polyester fiber (V4) was prepared.

<Preparation of fibrillated fiber>
An average fiber separated from the trunk after PBO fiber (Zylon AS, 1.7 dtex × 3 mm) manufactured by Toyobo Co., Ltd. was repeatedly treated 15 times using a double disc refiner and then 20 times using a high pressure homogenizer at 50 MPa. A fibrillated PBO fiber (X5) having a diameter of 0.9 μm was prepared.

<Preparation of fibrillated fiber>
Toyobo PBO fibers (Zylon AS, 1.7 dtex × 3 mm) were repeatedly treated 20 times using a single disc refiner, and fibrillated PBO fibers in which branches having an average fiber diameter of 1 μm or less were generated from a trunk having an average fiber diameter of 3 μm ( Y5) was prepared.

<Preparation of fibrillated fiber>
Toyobo's PBO fiber (Zylon AS, 1.7 dtex × 3 mm) treated with 15,000 revolutions using a PFI mill, and a fibrillated PBO fiber having a fiber diameter of 1 μm or less detached from the trunk, and a trunk having an average fiber diameter of 3 μm To prepare fibrillated PBO fibers (XY5) in which branches having an average fiber diameter of 1 μm or less were generated.

<Preparation of fibrillated fiber>
Toyobo's PBO fiber (Zylon AS, 1.7 dtex × 3 mm) was repeatedly treated seven times using a single disc refiner, and fibrillated PBO fiber (branched portion having an average fiber diameter of 2 μm or less was generated from a trunk having an average fiber diameter of 8 μm ( V5) was prepared.

<Organic fiber>
The following fibers were used as organic fibers.
Organic fiber (Z1): Teijin's polyethylene terephthalate fiber (Teijin Tetron Tepyrus, 0.1 dtex × 3 mm, fiber diameter of about 4 μm)
Organic fiber (Z2): Teijin's polyethylene terephthalate fiber (Teijin Tetoron Tepyrus, 0.6 dtex × 3 mm, fiber diameter of about 7 μm)
Organic fiber (Z3): Core sheath polyester fiber (Melty, 1.5 dtex × 5 mm, fiber diameter of about 13 μm, core: polyethylene terephthalate having a melting point of 255 ° C., sheath: polyethylene terephthalate component and polyethylene isophthalate component Copolyester, melting point 110 ° C)
Organic fiber (Z4): split fiber acrylic fiber manufactured by Mitsubishi Rayon Co., Ltd. (Bonnell MVP, 0.1 dtex × 3 mm, fiber diameter of about 4 μm)
Organic fiber (Z5): Kuraray's wholly aromatic polyester fiber (Vectran, 1.7 dtex × 5 mm, fiber diameter of about 12 μm)
Organic fiber (Z6): Kuraray aromatic polyamide fiber (Genesta, 0.08 dtex × 3 mm, fiber diameter of about 3 μm)
Organic fiber (Z7): Para-type wholly aromatic polyamide fiber manufactured by Teijin Techno Products (Technora, 1.2 dtex × 5 mm, fiber diameter of about 11 μm),
Organic fiber (Z8): manufactured by Toyobo Co., Ltd., PBO fiber (Zylon, 1.7 dtex × 5 mm, fiber diameter of about 12 μm)
Organic fiber (Z9): Teijin's polyethylene terephthalate fiber (Teijin Tetron TT04 6.6 dtex × 5 mm, fiber diameter of about 25 μm)
Organic fiber (Z10): Lyocell monofilament manufactured by Lenzing (1.7 dtex × 4 mm, fiber diameter of about 12 μm)

<Preparation of slurry>
A slurry was prepared using a pulper according to the raw materials and contents shown in Tables 1 and 2.

Examples 1-30
Wet paper was made under the conditions shown in Table 3 and dried with a cylinder dryer (130 ° C.) to produce stencil sheet paper of Examples 1-30. In the table, “circular net” means a circular paper machine, “inclined” means an inclined paper machine, and “inclined short net” means an inclined short paper machine.

(Comparative Examples 1-6)
Wet paper was made under the conditions shown in Table 4 and dried with a cylinder dryer (130 ° C.) to produce thin paper for stencil printing of Comparative Examples 1-6.

(Comparative Example 7)
90 parts by mass of fibrillated lyocell fiber (V1) and 10 parts by mass of a polyvinyl alcohol binder fiber (1.1 dtex × 3 mm, dissolution temperature in water of 75 ° C.) manufactured by Kuraray Co., Ltd. were dispersed in water to prepare a slurry. This slurry was made with a circular paper machine and dried at a dryer temperature of 110 ° C. to produce a thin paper for stencil printing of Comparative Example 7 having a basis weight of 9.0 g / m ² .

<Physical properties evaluation of thin paper for stencil printing>
Tensile strength (unit: N / m): In accordance with JIS P8113, the stencil sheet for stencil printing of Examples and Comparative Examples was cut into a width of 15 mm and a length of 200 mm, and a Tensilon measuring machine (STAR-1150, manufactured by Orientec Co., Ltd.) Using, the load at break was measured 10 times each and the average value was shown.

  Water resistance: The stencil thin papers of Examples and Comparative Examples were immersed in water for 10 minutes. At this time, the entire sample is immersed in water. After 10 minutes, the corner of the sample taken out of the water was sandwiched between clips and hung vertically, and left to stand for 15 minutes to drain water. Next, the tensile strength was measured by the same method as the above-described tensile strength evaluation, and the water resistance strength was evaluated.

<Printability evaluation of thin paper for stencil printing>
A thermoplastic polyester film having a thickness of 3 μm was bonded to one side of the thin paper for stencil printing of Examples and Comparative Examples with a vinyl acetate adhesive to produce a stencil base paper. This stencil sheet was punched with a thermal head to make a plate. Printing was performed using oil-based ink and water-based ink, the number of printing durability was evaluated, and the results are shown in Tables 5 and 6.

<Image quality evaluation of thin paper for stencil printing>
A thermoplastic polyester film having a thickness of 3 μm was bonded to one side of the thin paper for stencil printing of Examples and Comparative Examples with a vinyl acetate adhesive to produce a stencil base paper. This stencil printing base paper was punched with a thermal head to produce a plate making having an image to be a black solid portion of 50 mm × 50 mm. Printing was performed using oil-based ink, the presence or absence of white spots was evaluated, and the results are shown in Tables 5 and 6. Those with white spots were marked with ×, those without white spots were marked with ◯, and those with white spots but at a usable level were marked with Δ.

  Since the stencil sheet of the example uses fibrillated fibers having an appropriate degree of fibrillation, the white spots in printing were less than the stencil sheet of comparative example. Moreover, since the water-resistant strength is high, even when a water-based ink is used, a high printing durability is obtained as in the case of an oil-based ink. The thin paper for stencil printing of Comparative Example 7 exhibited a mechanical strength by hydrogen bonding, and therefore had a low water resistance strength and a low printing durability when water-based ink was used. In addition, since the thin paper for stencil printing of Examples 1-25 and Examples 27-36 contained the heat-fusible binder fiber, the mechanical strength was high and the printing durability was excellent.

  INDUSTRIAL APPLICABILITY The present invention can be used for stencil printing thin paper that is perforated and engraved by a thermal head or the like by irradiation with flash light such as a halogen lamp, a xenon lamp, or a flash bulb, infrared irradiation, pulse irradiation such as laser light.

Claims (5)

  (X) At least one of two types of fibrillated fibers: a fibrillated fiber having a fiber diameter of 1 μm or less detached from the trunk, and (Y) a fibrillated fiber having a branch having a fiber diameter of 1 μm or less generated from a trunk having a fiber diameter of 2 μm or more. And (Z) a thin paper for stencil printing comprising an organic fiber having a fiber diameter of 1 to 30 μm.   The thin paper for stencil printing according to claim 1, wherein the fibrillated fibers (X) and (Y) are at least one selected from fibrillated lyocell fibers, fibrillated acrylic fibers, and fibrillated aromatic polyamide fibers. .   The thin paper for stencil printing according to claim 1 or 2, wherein at least a part of the organic fiber (Z) is a heat-fusible binder fiber.   The thin paper for stencil printing according to any one of claims 1 to 3, wherein the organic fiber (Z) is a polyester fiber.   The total content of (X) and (Y) is 1 to 98% by mass and the content of (Z) is 2 to 99% by mass with respect to the stencil thin paper. The thin paper for stencil printing in any one of -4.