JP2014151450A - Thermosensitive stencil printing base paper and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent printing wrinkles and dimensional elongation of an image in long-term printing, in thermosensitive stencil printing base paper.SOLUTION: Thermosensitive stencil printing base paper has a thermoplastic resin film including a porous resin film, and a porous fiber film bonded onto the thermoplastic resin film with an adhesive. A solventless type polyurethane adhesive is used as the adhesive. On both short-side-direction ends of the thermosensitive stencil printing base paper, a reinforcing portion is provided which is formed by curing the porous resin film and the adhesive made to enter into the porous fiber film. The thickness of the reinforcing portion is set to a total thickness of the porous resin film and the porous fiber film, or less.

Description

  The present invention relates to a high-quality heat-sensitive stencil paper used for a heat-sensitive stencil printing apparatus and free from wrinkling resistance and image size elongation, and a method for producing the same.

  As a printing base paper for a thermal stencil printing machine, conventionally, a thermal stencil base paper in which a porous thin paper mixed with natural fiber or synthetic fiber alone or mixed with an adhesive is used as an ink-permeable support on a thermoplastic film is used. I came. However, a heat-sensitive stencil sheet using a porous thin paper made of such fibers as a support has the following problems. By sticking the porous thin paper and the film together using an adhesive, the adhesive may accumulate like a web of water between the fibers of the porous thin paper. For this reason, there is a problem that the portion is difficult to be perforated by the thermal head, and the passage of the ink is hindered to cause uneven printing. In addition, the porous thin paper fiber itself hinders the passage of ink, and printing unevenness is likely to occur. Furthermore, the smoothness of the film surface is lowered due to the fibers of the porous thin paper, the adhesion with the thermal head is poor, and an unperforated portion is formed, resulting in a problem of uneven printing. In order to improve these problems, in recent years, a thermoplastic resin film has a porous resin film made of resin on one surface, and a porous fiber film made of a fibrous material is further laminated on the surface. Stencil papers are already known.

  However, the heat-sensitive stencil paper used in recent years uses a very thin porous thin paper to prevent the fibers themselves of the porous fiber membrane from interfering with the ink passage, and the stiffness is weak. If the stiffness is weak, there is a problem that printing wrinkles and image dimension elongation at the time of printing are generated. In order to solve this problem, various proposals have been made.

  For example, in Patent Document 1, in a roll-type heat-sensitive stencil sheet made by laminating a film and a porous thin paper, in order to prevent misfeeding during stencil feeding, an acrylic system is used at the end in the longitudinal direction of the stencil. A device provided with a reinforcing portion by applying 50 μm of adhesion has been proposed.

  Further, in Patent Document 2, in a roll-type heat-sensitive stencil sheet made by laminating a film and porous thin paper, an interval necessary for one-time plate-making and printing is prevented in order to prevent misfeeding at the time of plate feeding. There has been proposed a structure in which a reinforcing portion is provided in the short direction.

  Further, in Patent Document 3, a roll-type heat-sensitive stencil sheet made by laminating a film and porous thin paper is pasted with a 100 μm reinforcing paper at the cue portion in order to prevent wrinkles and the like from being generated. The thing which provided the reinforcement part by this is proposed.

  Further, in Patent Document 4, in a roll-type heat-sensitive stencil sheet made by laminating a film and a porous thin paper, a plate-making part is provided at the longitudinal end of the sheet in order to prevent wrinkles during the feeding. A harder guide hole has been proposed.

  Further, Patent Document 5 proposes a small rotary rolling photoengraving printing machine that performs plate making by photoelectric conversion using a writing means comprising a heating element and uses a roll-shaped heat-sensitive stencil sheet. With this apparatus, no slack occurs on the heat-sensitive stencil sheet, and writing can be performed with high accuracy.

  Further, in Patent Document 6, for the purpose of obtaining a better printed image on a stencil printing base paper, plate making is performed on a portion that is substantially composed only of a thermoplastic synthetic resin film and wound around a feed roller or the like. In order to reliably convey the sheet to the clamper, a stencil printing base paper has been proposed which has a conveying portion having a reinforcing portion continuous with the plate-making portion for each plate length.

  Further, in Patent Document 7, a reinforcing resin is provided in contact with positions corresponding to both ends of the heat-sensitive stencil sheet, and then a porous resin film and a porous fiber film provided on the thermoplastic resin film are provided. A heat-sensitive stencil paper that has been bonded with an adhesive has been proposed.

  Further, in Patent Document 8, a reinforcing layer is attached by sticking a reinforcing paper before the free end portion is clamped by a clamper in a printing apparatus in order to prevent the free end portion of the stencil sheet from curling. Is described.

However, in recent years, heat-sensitive stencil printing, which has a porous resin film made of resin on one surface of a thermoplastic resin film, and is further laminated with a porous fiber film made of a fibrous material on the surface thereof The base paper is made thin. (Thickness of about 35 μm). If both ends of this base paper are configured such that a reinforcing paper is applied as described above or an acrylic adhesive is applied thickly, the thickness of both ends and the center can be different. As a result, the central portion is lifted during printing, and conversely, dimensional elongation occurs in the printing durability and the image.
Further, in the invention described in Patent Document 7, in the manufacturing process, the reinforcing portion is manufactured in a separate process, so that the displacement of the reinforcing portion occurs, and the resin spreads to control the thickness and width of the reinforcing portion. However, there is a problem that the flatness is deteriorated due to the resin protruding on the porous fiber membrane or the like. In addition, since a separate step of arranging the reinforcing resin is required, there are problems that the number of steps and the cost increase.

  The present invention has been made in view of the above circumstances, and includes a thermoplastic resin film provided with a porous resin film, and a porous fiber film bonded to the porous resin film with an adhesive. For stencil printing, heat-sensitive stencil printing that can improve the stiffness of the base paper, improve transportability, and prevent printing wrinkles and image size elongation at the time of printing. The purpose is to provide a base paper.

  In order to solve the above problems and achieve the object, the present invention has a thermoplastic resin film provided with a porous resin film, and a porous fiber film bonded to the porous resin film with an adhesive. A heat-sensitive stencil printing base paper, wherein the adhesive is a solventless polyurethane adhesive, and enters the porous resin film and the porous fiber film at both ends in the short direction of the heat-sensitive stencil printing base paper. The reinforcing part is formed by curing the adhesive, and the thickness of the reinforcing part is equal to or less than the total thickness of the porous resin film and the porous fiber film. Is.

  According to the present invention, the reinforcing strength of the non-solvent polyurethane adhesive is provided at both ends in the short direction of the heat-sensitive stencil base paper, so that the stiffness of the base paper can be enhanced. Transportability can be provided. Further, by using a solventless polyurethane adhesive, the thickness and width of the reinforcing portion can be set to desired values with good reproducibility, so that the yield can be improved and the cost can be reduced. Furthermore, since the thickness of the reinforcing part is less than or equal to the total thickness of the porous resin film and the porous fiber film, there is no step between the both ends and the center of the heat-sensitive stencil sheet, so It is possible to prevent wrinkles and image size elongation at the time of printing, and to obtain excellent image quality.

It is a perspective view of the form which rolled up the heat sensitive stencil printing base paper of this invention in roll shape. It is a schematic sectional drawing of the base paper for heat-sensitive stencil printing of this invention. It is a schematic diagram which shows the adhesive agent coating part and bonding coater which are used for the manufacture process of the base paper for heat-sensitive stencil printing of this invention. It is a schematic diagram which shows sectional drawing of the scraping blade which has a recessed part used for manufacture of the base paper for heat-sensitive stencil printing of this invention, and its usage method. FIG. 6 is a top view showing a document used for evaluation of printing durability.

The heat-sensitive stencil sheet of the present invention will be described below with reference to the drawings. FIG. 1 shows a perspective view of a form of the heat-sensitive stencil sheet of the present invention wound up in a roll shape. FIG. 2 shows a cross-sectional view of the heat-sensitive stencil sheet of the present invention.
As shown in FIGS. 1 and 2, the heat-sensitive stencil sheet 10 of the present invention was bonded to a thermoplastic resin film 11 provided with a porous resin film 12 and an adhesive on the porous resin film 12. A heat-sensitive stencil sheet having a porous fiber film 13, and an adhesive that has entered the porous resin film 12 and the porous fiber film 13 at both ends in the short direction of the heat-sensitive stencil sheet. A reinforced portion 15 formed by curing is provided. Further, as shown in FIG. 2, the thickness of the reinforcing portion 15 is substantially the same as the total thickness of the porous resin film 12 and the porous fiber film 13. In a region other than both end portions, the porous resin film 12 and the porous fiber film 13 have an adhesive portion 14 bonded with an adhesive.

Note that the short direction is a direction perpendicular to the transport direction X in the plane of the heat-sensitive stencil sheet as shown in FIG.
And the said both ends show the area | region which has a fixed width | variety from the outermost both ends of the said transversal direction of the heat-sensitive stencil base paper, and an image is not formed.
The width of both ends is determined in consideration of the area where this image is not formed.
It is desirable that the reinforcing portion 15 is formed on all of both ends parallel to the longitudinal direction of the heat-sensitive stencil sheet.

The thickness of the reinforcing portion 15 was substantially the same as the total thickness of the porous resin film 12 and the porous fiber film 13. The adhesive coating weight of the reinforcing portion is preferably, 12 g / ^{m 2} or more 15 g / ^{m 2} or less and most preferably equal to 8 g / ^{m 2} or more 15 g / ^{m 2} or less. If it is less than 8 g / m ² , the porous fiber membrane cannot be reinforced and sufficient strength cannot be obtained, and if it exceeds 15 g / m ² , the total of the porous resin membrane 12 and the porous fiber membrane 13 is not preferable. It becomes thicker than the thickness, and the in-plane smoothness of the heat-sensitive stencil sheet is deteriorated.

<Thermoplastic resin film>
The thermoplastic resin film is not particularly limited in material, thickness, size, shape and the like, and can be appropriately selected from known ones commonly used for heat-sensitive stencil printing masters according to the purpose.
Examples of the thermoplastic resin include polyester resin, polyamide resin, polyethylene resin, polypropylene resin, polyvinyl chloride resin, polyvinylidene chloride resin, vinyl chloride-vinylidene chloride copolymer, and the like.
Examples of the polyester resin include a polyethylene terephthalate resin, a copolymer of ethylene terephthalate and ethylene isophthalate, a copolymer of hexamethylene terephthalate and cyclohexanedimethylene terephthalate, etc. From the viewpoint of increasing, a copolymer of ethylene terephthalate and ethylene isophthalate, and a copolymer of hexamethylene terephthalate and cyclohexanedimethylene terephthalate are particularly preferable.

  If necessary, the thermoplastic resin film includes a flame retardant, a heat stabilizer, an antioxidant, an ultraviolet absorber, an antistatic agent, a lubricant such as a pigment, a dye, a fatty acid ester, and a wax, and an antifoaming agent such as polysiloxane. An agent or the like can be blended. Furthermore, for the purpose of imparting easy slipperiness, for example, inorganic particles such as clay, mica, titanium oxide, calcium carbonate, kaolin, talc, wet silica, dry silica; organic particles containing acrylic acid, styrene and the like as constituent components Or a method of applying a surfactant.

As the thermoplastic resin film, a biaxially stretched resin film is preferable. Examples of the biaxially stretched resin film include a biaxially stretched polyester resin film, a biaxially stretched polyethylene resin film, and a biaxially stretched polypropylene resin film. Is mentioned.
The thickness of the thermoplastic resin film is preferably 0.1 to 5.0 μm, and more preferably 0.1 to 3.0 μm. When the thickness is less than 0.1 μm, the film formation stability may be deteriorated due to being too thin, and the printing durability may be lowered. When the thickness exceeds 5.0 μm, the piercing property may be lowered.

<Porous resin film>
As long as the porous resin film has a structure having a large number of voids inside and on the surface, the shape of the void, the average pore diameter, the porosity, etc. are not particularly limited, and should be appropriately selected according to the purpose. Can do. The shape of the void is preferably a continuous structure in the thickness direction, for example, connected in an irregular rod shape, spherical shape, or branch shape (not a short constitutional unit such as Japanese paper is intertwined, printing Those having a complicated three-dimensional structure (which is not a combination of simple shapes formed by, etc.), a structure resembling a so-called yarn string, a honeycomb-like structure, a honeycomb-like structure, and the like are preferable.

  As a first method for forming a porous resin film having the above-described structure, for example, as disclosed in JP-A-10-24667, a good resin solvent (resin can be dissolved) that forms a porous resin film ) And poor solvents (solvents that do not substantially dissolve the resin and whose evaporation rate is slower than the evaporation rate of the good solvent) are dissolved well. A fluid containing a solvent and a poor solvent is applied in a semi-precipitated state on a thermoplastic resin film and dried to form. The fluid containing this resin, its good solvent, and poor solvent has a three-dimensional network-like structure in which the good solvent evaporates first, the poor solvent increases relatively, the resin precipitates due to resin concentration, etc. Form a structure. In this first formation method, a porous resin film having a string-like structure is generally formed, and productivity can be increased by selecting a solvent that evaporates quickly, such as ether or acetone.

  The resin material constituting the porous resin film is not particularly limited and may be appropriately selected from known ones according to the purpose. For example, polyvinyl acetate resin, polyvinyl butyral resin, vinyl chloride-vinyl acetate copolymer Vinyl resins such as vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, styrene-acrylonitrile copolymer; polyamide resins such as polybutylene resin and nylon; polyphenylene oxide resin, (meth) acrylate resin, polycarbonate resin; acetyl Examples thereof include cellulose derivatives such as cellulose, acetylbutylcellulose, and acetylpropylcellulose. These may be used individually by 1 type and may use 2 or more types together.

  The porous resin film may further contain, for example, a filler, an antistatic agent, a stick preventing agent, a surfactant, an antiseptic, an antifoaming agent, etc., as long as the purpose and effect of the present invention are not impaired. Can be added.

The filler is added to adjust the formation, strength, pore size, stiffness, etc. of the porous resin film. Here, the filler is a concept including pigments, powders, and fibrous substances, and among these, needle-like, plate-like, or fibrous fillers are particularly preferable.
Examples of the filler include mineral needle fillers such as magnesium silicate, sepiolite, potassium titanate, wollastonite, zonolite and gypsum fiber; artificial minerals such as non-oxide needle whiskers and double oxide whiskers Examples thereof include plate-like fillers such as mica, glass flake, and talc; natural or synthetic fibrous fillers such as carbon fiber, polyester fiber, glass fiber, vinylon fiber, nylon fiber, and acrylic fiber.
There is no restriction | limiting in particular as said pigment, According to the objective, it can select suitably from well-known things. For example, organic polymer particles made of polyvinyl acetate resin, polyvinyl chloride resin, polymethyl acrylate resin, and the like; inorganic pigments such as carbon black, zinc oxide, titanium dioxide, calcium carbonate, and silica can be used. These may be used individually by 1 type and may use 2 or more types together.
The amount of the filler added is preferably 5 to 200 parts by mass with respect to 100 parts by mass of the resin. When the added amount of the filler is less than 5 parts by mass, curling may easily occur, and when it exceeds 200 parts by mass, the strength of the porous resin film may be reduced.

In addition, the porous resin film is formed by applying a water-in-oil type emulsion (a coating liquid for forming a porous resin film) containing a dissolved synthetic resin to the thermoplastic resin film with a certain thickness and drying. May be. In this case, the pore diameter uniformity of the porous resin film is high and the piercing property by the thermal head is high, so the image quality is excellent, there is little set-off, and there is no occurrence of jamming on the drum or wrinkles on the drum. The master which has the feature of it is obtained efficiently. Further, since the shape of the obtained porous resin film does not depend on the solubility of the resin, it is less affected by temperature and humidity, and is excellent in terms of high reproducibility of the formed film shape. Furthermore, since the degree of freedom of the formulation is high and the range in which the porous resin film can be formed is wide, it is excellent in that the range in which the viscosity of the coating solution can be adjusted by the ratio of the oil phase / water phase, the resin concentration, the resin molecular weight, and the like.
In other words, the second method for forming the porous resin film is used when a good solvent and a poor solvent of the resin constituting the porous resin film are not mixed with each other. For example, JP-A-11-235858 As disclosed in US Pat. No. 4, the method is a method in which a fluid mainly composed of a W / O type (water-in-oil) emulsion is applied onto a thermoplastic resin film and dried to form a porous resin film. . The porous resin film formed from this W / O type emulsion generally has a honeycomb-like structure and a honeycomb-like three-dimensional network structure. The porous resin film formed by the second forming method is formed by applying a fluid mainly composed of a W / O emulsion on a thermoplastic resin film and drying it. After the portion is dried, it becomes pores through which ink passes, and a resin in the solvent (which may contain additives such as fillers and emulsifiers) becomes a structure.

  There is no restriction | limiting in particular as said resin, According to the objective, it can select suitably, For example, acrylic resin, ester resin, urethane type resin, acetal type resin, olefin type resin, vinylidene chloride type resin, epoxy type Examples thereof include resins, amide resins, styrene resins, vinyl resins, cellulose derivatives, modified products thereof, and copolymers thereof, among which vinyl butyral resins and urethane resins are particularly preferable.

  For the formation of the W / O emulsion, a surfactant having a relatively strong lipophilic HLB of 2.5 to 6 is effective, but when a surfactant having an HLB of 8 to 20 is used in the aqueous phase, too. A more stable and uniform W / O emulsion can be obtained. The use of a polymeric surfactant is also one method for obtaining a more stable and uniform emulsion. In addition, addition of a thickener such as polyvinyl alcohol or polyacrylic acid to the aqueous system is effective for stabilizing the emulsion.

  In order to adjust the formation, strength, pore size, stiffness and the like of the porous resin film, an additive such as a filler can be further added to the porous resin film as necessary. Of these, needle-like, plate-like, or fibrous fillers are particularly preferred. In addition, as a filler, it can select suitably from the thing similar to the said 1st formation method.

As the dried adhesion amount of the porous resin film in the first and second forming method, preferably 0.5 to 20 g / ^{m 2,} 1 to 10 g / ^{m 2} is more preferable.
If the adhesion amount is less than 0.5 g / m ² , the amount of ink adhesion may be increased without controlling the ink adhesion amount, and if it exceeds 20 g / m ² , the passage of ink may be inhibited. The image may get worse.

<Porous fiber membrane>
There is no restriction | limiting in particular about a material, a magnitude | size, a structure, etc. as said porous fiber membrane, According to the objective, it can select suitably. Examples of the material include mineral fibers such as glass, sepiolite, and various metals; animal fibers such as wool and silk; natural fibers such as cotton, manila hemp, mulberry, mitsumata, and pulp; regenerated fibers such as sufu and rayon; polyester, Examples include synthetic fibers such as polyvinyl alcohol and acrylic; semi-synthetic fibers such as carbon fibers; and thin paper such as inorganic fibers having a whisker structure. Among these, a porous fiber membrane made by mixing natural fibers and synthetic fibers, and a porous fiber membrane consisting only of synthetic fibers are preferable. The porous fiber membrane obtained by mixing natural fibers and synthetic fibers is relatively inexpensive and can provide good ink permeability and bending stiffness. The porous fiber membrane made of the synthetic fiber is preferable because it is less dependent on the environment, such as mechanical strength and charging characteristics, and is thinner than natural fibers. In addition, the ink has excellent uniform permeability.

  The porous fiber membrane can be expected to prevent problems such as strength, dimensional change due to moisture absorption, and strength reduction by using synthetic fibers formed of a synthetic resin such as polyester or acrylic. There is a desirable range for the basis weight and thickness, but the present invention is not limited thereto.

The thickness (for example, diameter), length, and shape of the fibrous material constituting the porous fiber membrane is not particularly limited, and is appropriately selected depending on the perforated diameter of the thermoplastic resin film, the thickness of the film, and the like. The diameter (thickness) of the fibrous substance is preferably 20 μm or less, and more preferably 1 to 10 μm. If the diameter is less than 1 μm, the tensile strength may be weakened, and if it exceeds 20 μm, ink passage may be hindered and a white-out image due to fibers may occur.
The length of the fibrous substance is preferably 0.1 to 10 mm, and more preferably 1 to 6 mm. If the length of the fibrous material is less than 0.1 mm, the tensile strength may be weakened, and if it exceeds 10 mm, it may be difficult to uniformly disperse.

There is no restriction | limiting in particular in the basic weight of the said porous fiber membrane, According to the objective, it can select suitably, 1-20 g / m < ² > is preferable and 3-10 g / m < ² > is more preferable. When the basis weight exceeds 20 g / m ² , the ink permeability decreases and the image sharpness may decrease. When the basis weight is less than 1 g / m ² , sufficient strength as an ink-permeable support is obtained. It may not be possible.

  The porous fiber membrane may be a commercially available product or an appropriately formed one. In addition, there is no restriction | limiting in particular as a method of forming the said porous fiber membrane, According to the objective, it can select suitably, For example, it describes in Japanese Patent Publication No.49-18728, Japanese Patent Publication No.49-8809, etc. This method can be used. Further, the fiber mode is not particularly limited and can be appropriately selected according to the purpose. Examples thereof include papermaking paper obtained by wet papermaking of short fibers, non-woven fabrics, woven fabrics, screen wrinkles, etc. Among these, productivity From the viewpoint of cost, papermaking paper is preferred.

There is no restriction | limiting in particular as another layer, According to the objective, it can select suitably, For example, a heat-fusion prevention layer, an adhesive layer, etc. are mentioned.
The heat-fusion-preventing layer is provided on one surface of the heat-sensitive stencil printing base paper that comes into contact with the thermal head of the thermoplastic resin film in order to prevent fusion during perforation.
The anti-fusing layer is composed of silicone oil, silicone resin, fluorine resin, surfactant, antistatic agent, heat-resistant agent, antioxidant, organic particle, inorganic particle, pigment, dispersion aid, preservative, antiseptic. It is desirable to provide a thin layer made of foaming agent or the like.
The thickness of the heat fusion preventing layer is preferably 0.005 to 0.4 μm, and more preferably 0.01 to 0.4 μm.
The method for forming the heat fusion prevention layer is not particularly limited, but it is preferable to apply a solution diluted with water, a solvent or the like using a roll coater, a gravure coater, a reverse coater, a bar coater or the like, and then dry.

<Adhesive>
As the adhesive, a polyurethane-based adhesive is particularly preferable in order to obtain a predetermined adhesive strength and satisfy the above conditions. As the polyurethane-based adhesive, a solventless polyurethane adhesive capable of obtaining desired adhesive strength with a low adhesion amount is suitable. In the case of an aqueous / emulsion type polyurethane adhesive, a solventless polyurethane adhesive is preferably used from the viewpoint of expansion and contraction of the porous fiber film during application and deterioration of curling.

  The solventless polyurethane adhesive is not particularly limited and may be appropriately selected depending on the intended purpose. (1) One-component moisture-curable urethane prepolymer obtained by reaction of a polyol component and an isocyanate component, ( 2) A two-component curable adhesive that is divided into a polyol component and an isocyanate component.

  The polyol component is not particularly limited as long as it has a hydroxyl group at both ends and is a liquid, and can be appropriately selected according to the purpose. Examples thereof include polyether polyols and polyester polyols having hydroxyl groups at both ends. Can be mentioned.

  Examples of the isocyanate component include hexamethylene diisocyanate (HMDI), 2,4-diisocyanate-1-methylcyclohexane, 2,6-diisocyanate-1-methylcyclohexane, diisocyanate cyclobutane, tetramethylene diisocyanate, o-, m- and p-xylylene diisocyanate (XDI), dicyclohexylmethane diisocyanate, dimethyldicyclohexylmethane diisocyanate, hexahydrometaxylidene diisocyanate (HXDI), lysine diisocyanate alkyl ester (the alkyl part of the alkyl ester has 1 to 6 carbon atoms) Are preferred) aliphatic or cycloaliphatic diisocyanates; toluylene-2,4-diisocyanate (TD1), toluylene-2 6-diisocyanate, diphenylmethane-4,4′-diisocyanate (MDI), 3-methyldiphenylmethane-4,4′-diisocyanate, m- and p-phenylene diisocyanate, chlorophenylene-2,4-diisocyanate, naphthalene-1,5 -Aromatic diisocyanates such as diisocyanate, diphenyl-4,4'-diisocyanate, 3,3'-dimethyldiphenyl-4,4'-diisocyanate, 1,3,5-triisopropylbenzene-2,4-diisocyanate, diphenyl ether diisocyanate Etc. These may be used individually by 1 type and may use 2 or more types together.

  When a solventless polyurethane adhesive is applied to the porous fiber membrane, if the viscosity is too high, the fibers will drop and application failure will occur. Therefore, it is preferable to apply by lowering the viscosity by heating the roll.

  The adhesion amount of the adhesive at both ends is determined by the porous resin film and the porous fiber film entering the pores of the porous resin film and the porous fiber film when the porous resin film and the porous fiber film are bonded. The thickness is appropriately selected so as to be equal to or less than the total thickness of the film. It is desirable to select appropriately in consideration of the size, thickness, material, etc. of the pores of the porous fiber membrane and the porous resin membrane.

Further, there is no particular limitation as long as it is a region other than both end portions (adhesive portion 14 in FIG. 1), desired adhesive strength, and does not block the pores of the porous resin membrane and the porous fiber membrane. Can be selected as appropriate. 0.05-5.0 g / m < ² > is preferable and 0.1-3.0 g / m < ² > is more preferable.

  The viscosity of the adhesive is preferably 800 mPa · s to 1200 mPa · s, more preferably 900 mPa · s to 1100 mPa · s at 50 to 110 ° C. until the adhesive is completely cured.

In the heat-sensitive stencil printing base paper of the present invention, the adhesive strength between the thermoplastic resin film and the porous fiber membrane, and the adhesive strength between the porous fiber membrane and the porous resin membrane are 1.4 N / m or more is preferable, and 2.8 N / m or more is more preferable.
When the adhesive strength is less than 1.4 N / m, film peeling between the thermoplastic resin film and the porous fiber film, or between the porous resin film and the porous fiber film, during handling and transportation. Not only can it cause wrinkles, but it can cause problems such as elongation, peeling, and tearing of the master during printing. The upper limit of the adhesive strength is not particularly limited as long as the ink passage is not inhibited, and can be appropriately selected according to the purpose.

When the solventless adhesive is used, curing is preferably performed for the purpose of promoting the reaction.
The curing temperature is preferably 50 ° C. or lower, and more preferably 40 ° C. or lower.
When the temperature of the curing exceeds 50 ° C., the thermoplastic resin film may shrink and a curling problem may occur. The curing time is not particularly limited as long as the desired adhesive force can be obtained, and can be appropriately selected according to the purpose.

<Method for producing heat-sensitive stencil sheet>
Next, an example of the method for producing the heat-sensitive stencil sheet of the present invention will be described. FIG. 3 is a schematic diagram showing an adhesive coating part and a bonding coater used in the production process of the heat-sensitive stencil sheet of the present invention. FIG. 4 (a) shows a cross-sectional view of a blade having a concave portion used for producing the heat-sensitive stencil sheet of the present invention. FIG. 4B is a schematic diagram showing how to use the blade.
The method for producing the heat-sensitive stencil printing base paper is a method for producing a heat-sensitive stencil printing base paper in which a porous resin film is provided on a thermoplastic resin film, and a porous fiber film is adhered to the porous resin film with an adhesive. A method of (1) providing the porous resin film on one surface of the thermoplastic resin film; and (2) applying an adhesive to the surface of the gravure roll while rotating the gravure roll. And an adhesive on the surface of the gravure roll using a blade provided with recesses having a depth smaller than the thickness of the porous fiber film at positions corresponding to both ends in the short direction of the heat-sensitive stencil sheet. By scraping so that a desired amount remains, the amount of the adhesive in the region corresponding to the both end portions is increased by the amount corresponding to the recess than the amount of the adhesive in the region other than the both end portions. The process to leave, (3) A step of transferring the adhesive left on the surface of the gravure roll in contact with the porous fiber membrane; (4) a surface of the porous fiber membrane to which the adhesive is transferred; and the porous resin. Contacting the surface of the membrane not provided with the thermoplastic resin film, bonding the thermoplastic resin film provided with the porous resin film and the porous fiber membrane, and curing the adhesive The adhesive is a solventless polyurethane adhesive, and the adhesive is applied to the porous resin film and the porous fiber film at both ends in the short direction of the heat-sensitive stencil printing base paper. A reinforcing portion is provided which is hardened by being inserted and has a thickness equal to or less than the total thickness of the porous resin film and the porous fiber film.

According to the manufacturing method of the present invention, the amount of the adhesive in the region corresponding to both ends is adjusted using the blade provided with the recess having a depth smaller than the thickness of the porous fiber membrane. More than the amount of adhesive can be left by the amount corresponding to the recess. Thereby, the thickness of the reinforcing part can be less than or equal to the total thickness of the porous resin film and the porous fiber film, and for heat-sensitive stencil printing in which there is no step between the both ends and the central part. It is possible to obtain a base paper.
Further, at both ends of the heat-sensitive stencil printing base paper, reinforcing portions formed by allowing an adhesive to enter and curing simultaneously with the adhesion between the porous resin film and the porous fiber film can be provided. As a result, it is possible to prevent misalignment of the reinforcing portion, and there is no need to provide a separate step for providing the reinforcing portion. Therefore, while realizing cost reduction, high-quality heat-sensitive without printing wrinkles and image size elongation during printing. A stencil printing base paper can be obtained.
In addition, since a solventless polyurethane adhesive is used as the adhesive, the thickness and width of the reinforcing portion can be controlled with good reproducibility, and the yield can be improved or the cost can be reduced.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited to these Examples at all. As long as they do not deviate from the gist of the present invention, these examples are appropriately modified within the scope of the present invention.

<Thermoplastic resin film>
A biaxially stretched polyester film having a thickness of 2.0 μm was used as the thermoplastic resin film.

<Prescription of porous resin film coating solution>
Acetal resin (KS-1 manufactured by Sekisui Chemical Co., Ltd.) 1.5 parts by weight Acetal resin (KS-3 manufactured by Sekisui Chemical Co., Ltd.) 1.0 part by weight Talc 1.9 parts by weight Surfactant (SO15U manufactured by Nikko Chemical Co.) 0. 1 part by weight Surfactant (KF6012 manufactured by Shin-Etsu Chemical Co., Ltd.) 0.1 part by weight Surfactant (J711 manufactured by Johnson Co., Ltd.) 0.2 part by weight Ethyl acetate 43.0 parts by weight or more The above substances are dissolved and dispersed. To this, 20.0 parts by weight of water (HEC 1% solution) is slowly added while stirring to obtain a cloudy emulsion coating solution.

<Step of providing a porous resin film on a thermoplastic resin film>
A porous resin film was provided on one surface of the thermoplastic resin film using the porous resin coating solution prepared as described above. The emulsion coating solution was applied and dried on the biaxially stretched polyester film by a die coating method in an atmosphere of 20 ° C. and 50% RH so that the adhesion amount after drying was 2.0 g / m ² . . Then, after forming the porous resin film, it was wound up in the form of a porous resin coating film roll and disposed in the feeding portion 29.

<Porous fiber membrane>
As the porous fiber membrane 21, paper-made paper (basis weight 5 g / m ² , thickness 25 μm) made of two kinds of polyester fibers having a fineness of 0.2 denier and 1.1 denier was used. The porous fiber membrane 21 is wound in a roll shape and installed in the feeding portion 22.

<Adhesive>
A one-component urethane adhesive (Takenate A280 manufactured by Takeda Pharmaceutical Company Limited) was used as the adhesive. This adhesive is a solventless polyurethane adhesive.

<Process of applying adhesive>
Apply the adhesive at the gravure offset coating section. Hereinafter, this will be specifically described with reference to FIGS. 3 and 4. As shown in FIG. 3, the adhesive application unit includes an adhesive supply pan 24 in which an adhesive 23 is accommodated, a gravure roll 25, a scraping blade 26, an intermediate transfer roll 27, and a nip roll 28. Consists of
The adhesive supply pan 24 and the gravure roll 25 are heated to 100 ° C. by circulating hot water. The viscosity of the adhesive 23 heated in the adhesive supply pan 24 was about 1000 mPa · s.

As shown in FIG. 4A, the shape of the scraping blade 26 is provided with recesses 26a at positions corresponding to both ends in the short direction of the heat-sensitive stencil sheet, and the shape of the recess 26a is The width is 10 mm and the depth is 15 μm. The depth of the recess 26a is 15 μm, which is smaller than the thickness of the porous fiber membrane 21 (21 μm).
The recesses are provided at positions corresponding to both ends in the short direction of the heat-sensitive stencil sheet.
The width of the recess is preferably selected in consideration of the strength of the heat-sensitive stencil sheet, the spread of the adhesive in the manufacturing process, the final cutting width, and the like.

  The adhesive 23 is pumped up from the adhesive supply pan 24 by rotating the gravure roll 25 in the direction of the arrow, applied to the gravure surface, and the excess portion is scraped off by the blade 26 and measured. The scraping blade 26 is used to scrape the adhesive on the surface of the gravure roll 25 so that a desired amount remains, so that the amount of adhesive in the region corresponding to the both end portions can be reduced in the region other than the both end portions. A larger amount than the amount of adhesive is left for the amount corresponding to the recess 26a.

As shown in FIG. 4 (b), on the gravure roll 25, in an area corresponding to both ends, an amount corresponding to the concave portion of the scraping blade, an adhesive having a width of 10 mm and a height of 15 μm, More than the area remains. The coating amount in the region other than the both end portions is 0.2 g / m ² .

Next, the process of transferring the adhesive to the porous fiber membrane will be described.
The porous fiber membrane 21 is fed out from the feed-out unit 22, passes through a transport roll, and is transported to the adhesive coating unit.
The adhesive 23 left on the gravure roll 25 is transferred to the porous fiber film 21 via the intermediate transfer roll 27. The nip roll 28 is a rubber roll and is nipped by the intermediate transfer roll 27 with a low pressure.
Since the thickness of the adhesive 23 in the reinforcing portion 15 is thinner than the thickness 25 μm of the porous fiber membrane 21, the adhesive 23 at both ends is nipped by the nip roll 28 in an amount corresponding to a recess having a depth of 15 μm. To be pushed into the porous fiber membrane 21.

  Thereafter, the porous fiber membrane 21 to which the adhesive 23 has been transferred is conveyed to the bonding portion. The laminating portion includes a laminating roll 32 and a laminating nip roll 31.

On the other hand, the thermoplastic resin film 30 coated with the porous resin film 21 is fed out from the feeding portion 29 and conveyed to the bonding portion.
The porous fiber film 21 to which the adhesive 23 has been transferred and the porous resin film on the thermoplastic resin film 30 are overlapped on the surface of the bonding roll 32 and bonded by being nipped by the bonding nip roll 31. Combined. The bonding nip roll 31 is a rubber roll. At this time, the adhesive at both ends also enters the pores of the porous resin film, so that the reinforcing portions having a thickness equivalent to the total thickness of the porous resin film and the porous fiber film are formed at both ends. Provided.

  The heat-sensitive stencil sheet 33 bonded at the bonding unit is wound up by the winding unit 34. At this time, since the thickness of the adhesive 23 was equal to the total thickness of the porous resin film and the porous fiber film 21, no step was produced on the surface even when the adhesive film 23 was bonded.

  Thereafter, the heat-sensitive stencil base paper 33 wound in a roll is used for the purpose of accelerating the reaction. The curing time at a curing temperature of 30 ° C. may be performed until the desired adhesive force is obtained, and is particularly limited. is not.

  After curing, it is composed of 0.5 parts by weight of silicone oil (SF8422 manufactured by Shin-Etsu Chemical Co., Ltd.), 0.5 parts by weight of surfactant (Pricesurf A208 manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and 100.0 parts by weight of toluene. The anti-fusing agent was applied and dried on the surface of the thermoplastic resin film opposite to the porous resin film using a bar coater, and slit to A3 width to obtain the heat-sensitive stencil printing base paper of the present invention.

As a method for evaluating the characteristics of the heat-sensitive stencil sheet of this example, printing wrinkles and printing durability were evaluated.
<Evaluation of printing wrinkles>
The evaluation of printing wrinkles was performed using a heat-sensitive stencil base paper provided with the above-mentioned reinforcing portion and a heat-sensitive stencil base paper without a reinforcing portion so far. These were supplied to Ricoh Co., Ltd. Satellite A450 (400 dpi), and were subjected to plate making and printing using an original having a black solid of 110 mm × 380 mm on one side by a thermal head type plate making method, and the occurrence of wrinkles was confirmed. .
The conditions at the time of printing are as follows.
Environment: Normal temperature environment (23 ° C 50% RH)
Printing speed: Maximum speed (6s)
Printing mode: Character mode 10,000 sheets were printed, and every 1000th sheet was checked visually for wrinkles in the solid part of the printed image, and the number of sheets was checked for wrinkles. When the wrinkle did not occur, it was marked as “◯”, and when the wrinkle occurred, it was marked as “x”.

Table 1 shows the evaluation results.

  The heat-sensitive stencil sheet having no reinforcing part was wrinkled at the 7000th sheet, but the heat-sensitive stencil sheet having the reinforcing part was not wrinkled even at the 10,000th sheet.

<Evaluation of printing durability>
A heat-sensitive stencil base paper provided with a reinforcing portion of this example and a heat-sensitive stencil base paper without a reinforcing portion so far were prepared. These were supplied to Ricoh Co., Ltd. Satellite A410 (thermal head 400 dpi), and printing and plate making were performed by the thermal head type plate making method using the manuscript shown in FIG.
The conditions at the time of printing are as follows.
Environment: Low temperature environment (10 ° C, 20% RH)
Printing speed: Maximum speed (5s)
Printing mode: Character mode 4000 sheets were printed, the dimension between the measurement points of the 4000th sheet and the 10th sheet (l in the figure) was measured, and the dimensional elongation of the 4000th sheet was expressed as a ratio (%). The dimensions were measured with a scale between three measurement points (both ends and center) in the conveyance direction of the printing paper.

Table 2 shows the evaluation results.

  In the heat-sensitive stencil sheet having no reinforcing part, the dimensional elongation of 0.43 to 0.48 (%) was confirmed. It remained at 1 to 0.20 (%).

From the above, by using the heat-sensitive stencil printing base paper of the present invention, it is possible to suppress wrinkles and image size elongation during printing.
Further, by producing the heat-sensitive stencil printing base sheet according to the present invention, wrinkles and image size elongation during printing can be suppressed as described above. Furthermore, without providing a step of providing a reinforcing portion separately, in the conventional gravure roll method, it is possible to provide a heat-sensitive stencil sheet whose both ends are reinforced, and cost reduction can be realized.

DESCRIPTION OF SYMBOLS 10 Heat sensitive stencil printing base paper 11 Thermoplastic resin film 12 Porous resin film 13 Porous fiber film 14 Adhesion part 15 Reinforcement part 21 Porous fiber film 22 Feeding part 23 Adhesive 24 Adhesive supply pan 25 Gravure roll 26 Scraping Blade 27 Intermediate transfer roll 28 Nip roll 29 Feeding section 30 Thermoplastic resin film 31 Bonding nip roll 32 Bonding roll 33 Heat sensitive stencil sheet 34 Winding section

JP 59-016787 JP 59-016788 JP 59-016789 JP 59-016791 A JP 05-023347 A Japanese Patent Laid-Open No. 06-239047 JP 2006-315245 A Japanese Patent Laid-Open No. 09-076619

Claims (2)

A heat-sensitive stencil printing base paper comprising a thermoplastic resin film provided with a porous resin film, and a porous fiber film bonded to the porous resin film with an adhesive,
The adhesive is a solventless polyurethane adhesive,
Reinforcing portions formed by curing the adhesive that has entered the porous resin film and the porous fiber film are provided at both ends in the short direction of the heat-sensitive stencil printing base paper,
The base paper for heat-sensitive stencil printing, wherein a thickness of the reinforcing portion is equal to or less than a total thickness of the porous resin film and the porous fiber film. A method for producing a heat-sensitive stencil base paper, wherein a porous resin film is provided on a thermoplastic resin film, and a porous fiber film is adhered to the porous resin film with an adhesive,
(1) providing the porous resin film on one surface of the thermoplastic resin film;
(2) While rotating the gravure roll, an adhesive is applied to the surface of the gravure roll, and a depth smaller than the thickness of the porous fiber membrane at positions corresponding to both ends in the short direction of the heat-sensitive stencil sheet. Using a blade provided with a concave portion, the adhesive on the surface of the gravure roll is scraped so that a desired amount remains, so that the amount of adhesive in the region corresponding to the both end portions can be reduced. Leaving a larger amount corresponding to the recess than the amount of adhesive in the region;
(3) a step of transferring the adhesive left on the gravure roll surface in contact with the porous fiber membrane;
(4) The porous resin film is provided by abutting a surface of the porous fiber film on which the adhesive is transferred and a surface of the porous resin film on which the thermoplastic resin film is not provided. Bonding the thermoplastic resin film and the porous fiber membrane, and curing the adhesive;
Including
The adhesive is a solventless polyurethane adhesive,
The porous resin film and the porous fiber film are obtained by allowing the adhesive to enter and cure the porous resin film and the porous fiber film at both ends in the short direction of the heat-sensitive stencil printing base paper. A method for producing a heat-sensitive stencil sheet, comprising providing a reinforcing portion having a thickness equal to or less than the total thickness of the above.