JP2002200856A - Master for heat-sensitive stencil printing, apparatus for heat-sensitive stencil printing and method for heat- sensitive stencil printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a master for heat-sensitive stencil printing in which adhesive strength between a film and a porous resin membrane of the master is strong and they are hardly released with each other and in addition, tensile strength is strong and elongation is small without losing such characteristics as excellent quality of image and less setoff. SOLUTION: The master for heat-sensitive stencil printing characterized by providing the porous resin membrane on the face of a thermoplastic resin film and laminating a porous fiber membrane consisting of a fibrous substance on the surface and forming a thin membrane on the face of the film side of the porous resin membrane so as to adhere closely thereto is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a stencil printing master having a porous resin film on a surface of a thermoplastic resin film, a stencil printing apparatus and a stencil printing method.

[0002]

2. Description of the Related Art A master is known in which porous thin paper or the like is adhered to a film as an ink-permeable support with an adhesive, and a stick preventing layer for preventing sticking with a thermal head is provided on the film surface. Actually, a master in which a film is bonded to a mixture of hemp fiber, synthetic fiber, wood fiber and the like as a porous thin paper with an adhesive and an anti-stick layer is provided on the film surface is widely used.

However, such a conventional master has the following problems. (1) A large amount of adhesive is accumulated in the form of a bird's web in a portion where the film is in contact with the overlapped portion of the fiber, and it is difficult for the thermal head to pierce the portion. In addition, that portion hinders the passage of ink, and printing unevenness occurs. (2) The fibers themselves impede the passage of ink, causing printing unevenness. (3) When the printed papers overlap, a set-off occurs where the ink adheres to the back surface of the paper overlaid thereon.

Some masters have been proposed in consideration of these points. For example, JP-A-3-193445 discloses an ink-permeable support using ultrafine fibers having a fineness of 1 denier or less. According to this, the above (2)
Although the problem (1) is solved, the problems (1) and (3) remain.

Japanese Patent Application Laid-Open No. Sho 62-198459 discloses a method of forming a heat-resistant resin pattern having a substantially closed shape on a film by using a printing method such as gravure, offset, or flexo. I have. However, it is difficult to print a pattern having a line width of 50 μm or less with the current printing technology, and even if it is possible, the productivity is low and the cost is high. Moreover, in general, when the line width is 30 μm or more, the heat-resistant resin hinders perforation by the thermal head, and printing unevenness occurs.

Japanese Patent Application Laid-Open No. 4-7198 discloses that a master is manufactured by applying a mixed solution of a water-dispersible polymer and fine particles such as colloidal silica to the film surface and drying to form a porous layer. Plate making using a stencil printing machine made by Riso Kagaku Kogyo Co., Ltd.
SON ink jet recording ink (HG-48
No. 00 ink) is disclosed, but the porous layer obtained by this method has poor printing ink properties, and conventional heat-sensitive stencil printing inks cannot provide a sufficient density during printing and cannot be used practically. Not a target.

Japanese Patent Application Laid-Open No. 54-33117 discloses a master which does not use a support and consists essentially of only a film, which solves the problems (1) and (2). However, it creates new problems. One is that when the film has a thickness of 10 μm or less, its “stiffness” is weak, and it is difficult to convey the film.

As a solution to this, Japanese Patent Publication No. 5-7059
In Japanese Patent Application Laid-Open No. 5 (1999) -2005, there is disclosed an idea that the film is wound around the peripheral wall of the plate cylinder of the stencil printing machine without being cut, and the entire film rotates together with the rotation of the plate cylinder during printing. However, in this method, since the film and the plate receiving / discharging unit rotate with the rotation of the plate cylinder during printing, the moment of rotation increases, and the deviation from the rotation axis of the center of gravity is large. ,
There was a problem that it had to be larger. Another is that when the film has a thickness of 5 μm or more, its thermal sensitivity is low, and it is difficult to perform perforation by a thermal head.

As means for solving these problems, Japanese Patent Application Laid-Open
Japanese Patent No. 24667 discloses a master formed by applying a fluid containing a resin, a good solvent and a poor solvent to a film and drying the film to form a porous resin film. In the drying process, the resin is deposited due to a relative increase in the poor solvent due to evaporation of the good solvent in the drying process, concentration of the liquid, etc., and the resin is dried and a porous resin film composed of a three-dimensional network structure is formed on the film. It is formed. Certainly, the master is superior to previously known masters, and in normal use there are few problems. However, in a master using a porous resin film made of a resin as a support, the tensile strength of the support tends to be weak and brittle.

For this reason, when the present inventors perform a large amount of printing and then artificially jam the master on the plate cylinder and peel it off from the plate cylinder in order to remove it, the support has cracks. In some cases, the porous resin film is peeled off from the master film and the porous resin film remains on the plate cylinder. In addition, when printing is performed using a printing paper having a particularly large thickness, for example, a postcard or an envelope, a portion of the porous resin film corresponding to the edge of the postcard or the envelope may be peeled from the film by receiving a particularly large impact.

Further, in the case of a master using a porous resin film made of a resin as a support, plate (image) elongation is likely to occur when a large amount of printing is performed, which is insufficient as a master for mass printing. I understand.

As means for solving this problem, Japanese Patent Laid-Open No. 10-14 / 1998
Japanese Patent No. 7075 discloses a master having a support in which a porous fiber film made of a fibrous substance is laminated on a surface of a porous resin film. The use of this support solves the above-mentioned problems, but newly raises the following problems. Porous fiber membranes made of fibrous materials have poor surface smoothness, and when laminated, deteriorate the film surface smoothness,
This causes a decrease in piercing properties. Although the strength of the support is high, the adhesion between the film and the porous resin film is weak, so that peeling of the film occurs during printing. (In the master described in Japanese Patent Application Laid-Open No. H10-147075, since the strength of the support was low, the support and the film both stretched together, so that no peeling occurred.)

[0013]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances of the prior art, and does not lose excellent image quality and features with less set-off. It is an object of the present invention to provide a master which has a high adhesive strength to a resin film, is hardly peeled off, and has a high tensile strength and a low elongation.

[0014]

Means for Solving the Problems The present inventors have made a master for heat-sensitive stencil printing having a porous resin film on the surface of a thermoplastic resin film (hereinafter sometimes simply referred to as "film"). As a result of examining from various angles, it is preferable that the porous resin film does not exist as much as possible because it hinders ink passage and hinders perforation by the thermal head. And, while the porous resin film preferably has relatively small contact points with the film, if the components form random and appropriately sized holes, the passage of ink or the use of a thermal head They have found and proposed that they do not hinder perforation (Japanese Patent Application Laid-Open No. Hei 10-24667).

[0015] Japanese Patent Application Laid-Open No. Hei 10-24667 discloses that
A master by a manufacturing method is disclosed in which a mixed fluid containing a resin, a good solvent thereof, and a poor solvent is applied on a film and dried to form a porous resin film. In the drying process, the resin is deposited due to the relative increase of the poor solvent due to evaporation of the good solvent in the drying process, concentration of the liquid, and the like, and the porous resin film composed of a three-dimensional network structure is dried to form a porous resin film on the film. Formed.

As a result of studying the invention described in Japanese Patent Application Laid-Open No. Hei 10-24667 from various angles, the present inventor has found that the above-mentioned problem can be more sufficiently solved by the following novel master. Was able to reach.

A first aspect of the present invention is that a porous resin film is provided on a surface of a thermoplastic resin film, and a porous fiber film made of a fibrous substance is further laminated on the surface thereof. A thermosensitive stencil printing master, characterized in that a thin film, particularly a thin film containing a resin component of the porous resin film, is formed on a surface of the film in close contact with the thermoplastic resin film.

A second aspect of the present invention is that, in the above structure, the range of the porosity of the porous resin film in contact with the film via the thin film with respect to the perforated area D of the plastic resin film is (−).
0.0063D + 61)% or more (however, D ≧ 314 μm)
² ) A heat-sensitive stencil printing master characterized by the following.

A third feature of the present invention is that the porous resin film is formed by mixing a synthetic resin with a plurality of solvents having different solubilities and using a solubilized synthetic resin solution. The first and second thermosensitive stencil printing masters described above.

A fourth aspect of the present invention is the master for thermosensitive stencil printing according to any one of the first to third aspects, wherein the thin film contains a resin component of the porous resin film.

According to a fifth aspect of the present invention, there is provided the first to fourth heat-sensitive stencil masters, wherein the porous resin film and the thin film are formed in a single film forming step.

According to a sixth aspect of the present invention, the thin film stencil master according to any one of the first to fifth aspects is characterized in that the thin film is destroyed together with the film at the time of thermal perforation of the film to form a hole through which ink passes. It is.

A seventh aspect of the present invention is that when the thermoplastic resin film is perforated to an opening area ratio of 20% or more, the air permeability is 2.0%.
The heat-sensitive stencil printing master according to any one of the first to sixth aspects, wherein the heat-sensitive stencil master has a thickness of from 160 cm ³ / cm ² · second.

According to an eighth aspect of the present invention, there is provided the master for heat-sensitive stencil printing according to any one of the first to seventh aspects, characterized in that two or more porous fiber membranes made of fibers are laminated.

According to a ninth aspect of the present invention, there is provided a plate making apparatus for making a master by heat-melting and perforating the first to eighth masters, a plate cylinder around which the formed master is wound, and an inside of the plate cylinder. A heat-sensitive stencil printing apparatus comprising at least a provided ink supply mechanism and a pressing device for pressing a printing sheet against the master wound around the outer peripheral surface of the plate cylinder.

According to a tenth aspect of the present invention, a step of making a master by making the first to eighth masters through hot-melt perforation, and a step of winding the master thus formed around a plate cylinder provided with an ink supply mechanism therein. And a step of pressing a printing sheet against the master wound around the outer peripheral surface of the plate cylinder by a pressing device.

[0027]

FIG. 1 is a block diagram showing an embodiment of the present invention.
The present invention will be described in further detail with reference to FIGS. The master of the present invention has a porous resin film 4 on the thermoplastic resin film 1 surface, and further laminates a porous fiber film 7,
In addition, a thin film 8 containing a resin component of the porous resin film is formed on the film-side surface of the porous resin film 4 by closely contacting the thin film surface on the film. Reference numeral 4a denotes a void in the porous resin film, and 4b denotes a component of the porous resin film.

The "porous resin film" referred to here is a porous film formed by, for example, precipitating and coagulating a resin dissolved in a solvent. It is formed by a foam film composed of an aggregate of cells having a ceiling or an aggregate of open-cell cells shown in FIG. 2, and an aggregate film formed by adhering granular or fibrous resins shown in FIG. Means membrane. Further, the porous fiber membrane 7 includes plant fibers such as cotton and hemp, polyester,
It means a film formed of a thin paper made of a fibrous material such as a synthetic fiber such as polyvinyl alcohol.

The porous resin film is preferably formed by mixing a synthetic resin with a plurality of solvents having different solubilities and using a solubilized synthetic resin solution.

The porous resin film 4 has a perforated area D (D ≧ 314 μm) when the thermoplastic resin film 1 is perforated.
The porosity with respect to m ² ) is (−0.0063D + 61)%
It is desirable to be within the above range. If the ratio of the component 4b of the porous resin film in the film perforated portion is large, the film perforation and the ink permeability are deteriorated, and the dot reproducibility is reduced. More preferably, the porosity (−0.0063
The ratio of the number of perforations of the film satisfying D + 61)% or more is 80% or more of the perforated portion, whereby a printed image excellent in gradation is obtained.

As the master of the present invention, in addition to the above structure, when the thermoplastic resin film is perforated to an opening area ratio of 20% or more, the air permeability is 2.0 to 160 cm ³ / cm ² ···
Those having characteristics such as seconds, preferably 30 to 148 cm ³ / cm ² · second are preferred. The air permeability is 2.0
If the ink density is less than cm ³ / cm ² , the ink permeability is poor. If a low-viscosity ink is used in order to obtain a sufficient amount of ink, image bleeding, the side of the printing drum during printing, or the rear end of the wound master can be achieved. The phenomenon that the printing ink exudes from the ink occurs. In addition, the porosity in the porous resin film and the porous fiber film is often low, and it is easy to hinder perforation by the thermal head. On the other hand, if the air permeability exceeds 160 cm ³ / cm ² , the effect of suppressing the ink by the porous resin film and the porous fiber film is reduced, and the ink between the printing drum and the film is excessively extruded at the time of printing, so that the back stain and Problems such as bleeding occur, and good print quality cannot be obtained even if the air permeability is too small.

If the thin film constituting the master of the present invention is present as it is, ink does not pass therethrough, and thus no printed image is formed. However, the thin film is destroyed together with the film when the thermal head pierces the film, and a hole through which ink passes is formed. The mechanism by which the holes are formed is not clear, but it is presumed that the thin film adhered to the film also forms holes in the process of expanding the holes due to the strain during stretching during hot perforation. You. Therefore, if the resin forming the thin film, that is, the resin of the porous resin film, is too hard, the thermal sensitivity is deteriorated, and the thermal perforation is hardly performed. However, on the contrary, care must be taken when selecting a resin that is too soft, since it reduces the stiffness of the master.

On the other hand, if the thickness of the thin film is too large, perforation by heat is hindered, and the thermal sensitivity deteriorates. Although it depends on the thermal sensitivity of the film and the margin of the thermal head, it is desirable that the thickness of the thin film does not exceed the thickness of the film. However, if the thickness is too small, the improvement in adhesion between the porous resin film and the film and the contribution to the smoothness of the film become small. Therefore, it is preferable that the thickness is 1% or more of the thickness of the film. Also, if the thickness is too large, it is easy to hinder perforation by the thermal head.
m or less.

As the resin material constituting the porous resin film and the thin film of the master of the present invention, for example, polyvinyl acetate,
Vinyl resins such as polyvinyl butyral, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, styrene-acrylonitrile copolymer, polyamides such as polybutylene and nylon, polyphenylene oxide, (meth) acrylic acid Esters, polycarbonate, acetylcellulose, acetylbutylcellulose,
Cellulose derivatives such as acetylpropylcellulose and the like can be mentioned. Each resin may be used alone or in combination of two or more.

In order to control the formation, strength, pore size, and stiffness of the porous resin film of the master of the present invention, additives such as fillers can be added to the porous resin film as needed. . Here, the filler is a concept including pigments, powders, and fibrous substances. Among them, needle-like, plate-like, or fibrous fillers are particularly preferable.

Specific examples thereof include mineral needle fillers such as magnesium silicate, sepiolite, potassium titanate, wollastonite, zonolite, and gypsum fiber, non-oxide needle whiskers, oxide whiskers, and double oxidation. Mineral whiskers and other artificial mineral fillers, mica, glass flakes, talc and other plate-like fillers, carbon fibers, polyester fibers, glass fibers, vinylon fibers, nylon fibers, acrylic fibers, and other natural or synthetic fibrous fillers Is mentioned.

As the pigment, organic polymer particles such as vinyl acetate, polyvinyl chloride, and polymethyl acrylate, and inorganic pigments such as carbon black, zinc oxide, titanium dioxide, calcium carbonate, and silica can be used.

The amount of these additives is preferably 5 to 200% by weight based on the resin constituting the porous resin film and the thin film. If the amount is less than 5% by weight, curling tends to occur. If the amount exceeds 200% by weight, the strength of the porous resin film may be reduced.

Further, the porous resin film and thin film of the present invention include:
An antistatic agent, an anti-stick agent, a surfactant, a preservative, an antifoaming agent and the like can be used in combination as long as the effects of the present invention are not impaired.

An extender may be added to the thin film in order to improve the adhesion and strength between the film and the thin film. As typical extenders used in the present invention, general pigments can be used. For example, pearlite powder, precipitated barium sulfate, barium carbonate, carbonated coal powder, precipitated calcium carbonate, kaolin, clay, silica, hydrous silicic acid, talc, basic magnesium carbonate, alumina white, broth white, satin white, zinc white , Basic lead carbonate,
There are extenders such as basic lead sulfate, lead sulfate, zinc sulfide and titanium oxide. These are so-called fillers. In addition, those whisker-like ones can be used without any problem. More preferably, oxide-based whiskers and double-oxide-based whiskers are selected. For example, potassium titanates, potassium borates, needle-like titanium oxides, and the like are optimal.

Examples of the film used in the heat-sensitive stencil master of the present invention include films conventionally used in heat-sensitive stencil masters such as vinyl chloride, vinyl chloride-vinylidene chloride copolymer, polypropylene and polyester. An axially stretched polyester can be suitably used. The thickness of the film is 0.5 to 10 μm, more preferably 1.0 to 5.0 μm. If it is less than 0.5 μm, it is too thin to apply the resin liquid, and if it exceeds 10 μm, it becomes difficult to perforate with a thermal head.

Also in the master of the present invention, a stick prevention layer for preventing stick with a thermal head can be provided on the opposite surface of the "film" on which the porous resin film and the thin film are formed. In this case, as the stick preventing agent to be used, a silicone-based releasing agent, a fluorine-based releasing agent, a phosphate ester-based surfactant and the like generally used in a conventional heat-sensitive stencil master can be used.

In the master of the present invention, it is preferable that the resin of the porous resin film and the resin of the thin film share at least a part of the composition components. In the known master, holes continuous in the thickness direction of the porous layer continued to the film, but in the master of the present invention, the holes did not continue to the film, and the resin continuous from the porous resin film at the boundary with the film. It is blocked by a thin film having a composition. That is, the porous resin film has a structure in contact with the entire surface of the film via the thin film, and because of such a structure, the master according to the present invention is more porous than the master having no thin film. Since the film and the film are adhered with a large adhesive strength, even if the master is torn during printing, the porous resin film can be removed without leaving the plate cylinder of the printing press. This is a completely different structure from the conventional master in which the porous resin film is in contact with the film only in a limited area, and furthermore, the thin film has almost no effect on the thermal sensitivity, and there is no new manufacturing process. An excellent effect that no work or equipment is required can be obtained.

The adhesive strength between the porous resin film (thin film) of the master and the film is 1.0 kg / cm ² or more, more preferably 2.0 kg / cm ² or more. The adhesive strength between the porous resin film (thin film) and the film is determined by applying a double-sided tape to both surfaces (the porous resin film surface and the film surface) of the master,
Cut into a size of mx 1 cm and adhere to the table with the film side down. Next, a plastic plate is attached to the spring scale, and one surface of the plate is adhered to the adhesive tape on the porous resin film surface. The spring scale is raised, and the porous resin film (thin film) and the scale when the film is peeled are read and measured.

The thin film of the master according to the present invention is characterized in that "there is a solvent A, B at least partially miscible, a resin R soluble in A and substantially insoluble in B, and at least A, B,
The fluid containing R "is applied to a film and dried to produce a porous resin film, and at the same time it can be formed in a single processing step. No special equipment, processes, etc. are required, which is a great advantage in this respect.

Forming a thin film in a single processing step simultaneously with the formation of the porous resin film can be achieved by forming a resin (corresponding to R), a resin-soluble solvent (corresponding to A), and a resin-insoluble solvent constituting the coating liquid for the porous resin film. (Equivalent to B), the mixing ratio, the characteristics of the film surface, the temperature and humidity at the time of application, the application speed, the drying conditions, and the like. In general, R has high solubility in A
The smaller the solubility in A, the greater the affinity of A with the film, and the greater the ratio of A to B, the easier it is to form a thin layer. These conditions also affect the pore size, distribution, etc. of the porous resin membrane and must be determined by careful experimentation. For example, if the ratio of A to B is too large, pores cannot be formed, and if it is too small, the pores become too large and the function of the porous resin film is impaired. The smoothness of the film surface is preferably 10,000 seconds or more. When the smoothness is 10,000 seconds or more, the adhesion between the film surface of the master and the thermal head is extremely excellent,
Good plate making quality is obtained.

Although the mechanism by which the porous resin film and the thin film are formed in a single processing step is not clear, as the resin-soluble solvent (corresponding to A) evaporates from the coated surface, the resin insoluble solvent (corresponding to B) on the surface portion is evaporated. ) Increases, and the resin begins to precipitate around the nucleus, which connects to form an irregularly shaped porous resin film, which in this process is separated from the coating surface at the boundary with the film Therefore, the resin-soluble solvent (corresponding to A) is present at a relatively high concentration,
Therefore, it is considered that a thin film having no pores is formed without depositing the resin. Therefore, the evaporation rate of A must be faster than that of B. The boiling point of A is 15-4 higher than that of B
Desirably, it is as low as 0 ° C.

The choice of the resin, the resin-soluble solvent (corresponding to A) and the resin-insoluble solvent (corresponding to B) is ultimately determined by experiments. For example, tetrahydrofuran (boiling point 65-
67 ° C.) is often used as A, and methanol (boiling point 64.5 ° C.) is also suitably used as A for polyvinyl butyral as a resin because of its low boiling point. Water is often used as B in terms of safety, cost and the like.

For coating, various types of coaters such as a blade, a transfer roll, a wire bar, a reverse roll, a gravure, and a die are used. Alternatively, a porous resin film may be laminated after a thin film is applied to the film surface with a blade, a wiper, or the like. At this time, it is preferable that the main component of the thin film is the same as the porous resin film.

The total thickness of the porous resin film and the thin film is preferably 5 to 100 μm, more preferably 6 to 50 μm.
It is. The amount of ink transferred to the paper during printing can be adjusted by the total thickness of the porous resin film and the thin film, and the thickness is 5 μm.
If it is less than, the porous resin film hardly remains behind the perforated portion after perforation by the thermal head, and therefore, the transfer amount of the printed matter tends to be easily deteriorated without controlling the ink transfer amount. On the other hand, when the thickness of the porous resin film exceeds 100 μm, the passage of ink is hindered, which causes image unevenness. The total adhesion amount of the porous resin film and the thin film is 0.5 to
25 g / m ^2, preferably 2 to 15 g / m ^2, especially 3 to 1
0 g / m ² is preferred. The thickness of the porous resin film and the thickness of the thin film are measured by a cross-sectional photograph by SEM. Furthermore, in order to increase the stiffness of the entire master, it is sufficient to use a thick film itself, but this will reduce the perforation sensitivity. Usually, the thickness of the film itself is preferably 7 μm or less. If the thickness exceeds 7 μm, it is too thick, and very large energy is required for perforation by the thermal head.

In the master for heat-sensitive stencil printing of the present invention, the thin film 8 and the porous resin film 4 are formed on the surface of the film 1 as described above, and then manufactured on the surface of the porous resin film 4 by a known method. The porous fibrous membrane 7 formed of the fibrous material thus formed is laminated. The adhesive used for laminating the porous resin film and the porous fiber film is such that if the viscosity of the adhesive is low, the adhesive enters the inside of the opening 3 of the porous resin film, and the ink permeability deteriorates. The viscosity of the adhesive is preferably high enough not to flow into the opening of the porous resin film. Further, a high-viscosity adhesive is applied to the surface of the porous fiber membrane with a roller, and laminated on the surface of the porous fiber membrane. Alternatively, a high-viscosity adhesive may be applied to the surface of the porous fiber membrane with a roller, and the adhesive may be dried before being laminated on the surface of the porous resin membrane. Alternatively, the resin liquid may be applied to the film surface, and before the resin film dries, the porous fiber film may be laminated on the resin liquid surface, dried, and the porous fiber film may be laminated on the porous resin film. In the heat-sensitive stencil master of the present invention, when the porous support made of a fibrous substance is not laminated on the outermost surface, the tensile strength is weak, and the heat-sensitive stencil master is stretched or cut during printing. Easier to do.

Examples of the porous fiber membrane 7 include mineral fibers such as glass, sepiolite and various metals; animal fibers such as wool and silk; plant fibers such as cotton and hemp; and regenerated fibers such as soup and rayon: polyester and polyvinyl alcohol. And synthetic fibers such as acrylic; semi-synthetic fibers such as carbon fiber; and thin paper such as inorganic fibers having a whisker structure. In this case, it is necessary to select an appropriate thickness of the fibrous substance depending on the diameter of the perforation, the thickness of the film, and the like, but the diameter is 20 μm or less, preferably 1 to 10 μm. If the diameter is smaller than 1 μm, the tensile strength is weak, and
If it is larger than μm, the passage of ink is hindered, and so-called white spots due to fibers appear in the image. The diameter of the fibrous substance may be converted into a circular diameter from denier and specific gravity. Further, the length of the fibrous substance is suitably 0.1 to 2 mm,
If it is longer than this, it becomes difficult to perform uniform dispersion.

The basis weight of the porous fiber membrane in the present invention is preferably 1 to 20 g / m ² , more preferably 3 to 10 g.
/ M ² . If the basis weight is more than 20 g / m ² , the ink permeability will be reduced and the image clarity will be reduced. In addition, basis weight is 1 g
If it is less than / m ² , sufficient strength as a support may not be obtained.

The method for producing the porous fibrous membrane comprising the fibrous substance in the present invention is not particularly limited, but it may be a paper made by short-fiber wet-making, a nonwoven fabric or a woven fabric, or a screen. A gauze or the like may be used, and papermaking paper can be preferably used in terms of productivity and cost.

In the heat-sensitive stencil master of the present invention, the relationship between the film and the fibrous material is such that when the film is perforated with a thermal head, two to seven fibrous materials cross each hole. More preferably, If the number of fibrous substances crossing the perforated portion is less than two, the effect of hindering the passage of ink is small and the effect of preventing set-off is small. If the number of fibrous materials is more than seven, the effect of hindering the passage of ink is too large and the printed image is blurred. Trouble occurs. The ratio of the number of perforations crossed by 2 to 7 fibrous substances is desirably 80% or more of the perforated portion.
Judgment is made with 100 perforations randomly selected from the micrograph. If even a part of the fibrous material purchase is perforated, it is determined to be one.

In the present invention, since the porous fiber film made of the fiber having a high tensile strength is laminated on the upper surface of the porous resin film having a relatively low tensile strength, the elongation at the time of printing of the master can be prevented. In addition, since the porous resin film exists between the film and the support made of fibers, the fibers overlap and the adhesive accumulates, and there is no hindrance to perforation by the thermal head. Further, since the ink is uniformly dispersed in the porous resin film, printing unevenness due to the overlapping of fibers does not occur.

In this embodiment, one layer of the porous fiber membrane is laminated, but two or more layers having different layer configurations may be laminated. At this time, the larger the gap in the upper layer, the better the ink dispersibility and the easier it is to obtain a uniform image. Further, when a porous fiber membrane of thick fibers is used, a master having higher printing durability can be obtained.

The stiffness of the master of the present invention has a bending stiffness of preferably 10 mN or more (by Lorentz Enstiffness Tester), more preferably 15 to 55 mN in consideration of transportability on a printing machine under various conditions. is there. The adjustment of the bending stiffness can be performed, for example, by adjusting the thickness and density of the porous resin film, and adding a filler or the like.

The "air permeability" in the present invention indicates the ink permeability of the master suitable for obtaining various excellent printing characteristics when the master is subjected to printing. This air permeability is measured as follows. First, the master film is perforated so that the opening area ratio of the surface thereof is 20% or more and 80% or less under specific conditions. At this time, the thin film is also perforated at the same time. About this sample, Perme
The air permeability is measured using an ameter (air permeability tester, manufactured by Toyo Seiki Seisaku-sho, Ltd.). Any of the samples having an opening area ratio of 20 to 80% has an air permeability of 2.0 to 160
cm ³ / cm ² · sec is preferable as the master for thermosensitive stencil printing according to the present invention. Specifically, samples with the opening area ratio of 20%, 50%, and 80% for the same product are prepared. In order to obtain a desired opening area ratio in the film, it is possible to arbitrarily change the energy applied to the thermal head and / or the size of the heating element of the thermal head.

As the punching device, PRIPORT VT
3820 (Ricoh: Toshiba thermal head)
Is used to make a plate with a 10 cm × 10 cm solid chart. The opening area ratio is a ratio of the total area of the through holes on the film surface of the master to the entire area. This measurement is performed as follows. That is, a magnified photograph of the perforated master is taken with an optical microscope (magnification: 100 times), and then enlarged and copied by a plain paper copier (Imagio 530, manufactured by Ricoh Company). The opening is marked on the OHP film.
Scan the OHP film with a scanner (300 DPI / 256
Gradation), image retouching software, Adobe
Binarization is performed using Photoshop 2.5J.
Then, the area ratio of the opening marked by the image analysis software is measured.

In the above example, for the sake of convenience, the film was measured with the opening area ratio of 20%, 50%, and 80%. However, the permeability of any sample having an opening area ratio of 20% to 80% was 2.0%. If it is １６０160 cm ³ / cm ² · second, it is regarded as a heat-sensitive stencil master according to the present invention. For example, if the opening area ratio is 65% and the air permeability is in the range of 2.0 to 160 cm ³ / cm ² · second, the master pierces the film with an opening area ratio of approximately 65% and performs printing. The printing characteristics aimed at by the invention can be obtained. The reason why the air permeability was measured with the opening area ratio being 20% or more was 20%.
This is because, when the percentage is less than%, even if the air permeability of the porous resin film is sufficient, the passage of the ink is hindered by the film when used for printing. If the air permeability of the master is too small or too large, good print quality cannot be obtained. If the air permeability is less than 2.0 cm ³ / cm ² · second, it tends to hinder the passage of the ink. If the air permeability exceeds 160 cm ³ / cm ² · second, the ink is excessively extruded, causing set-off and bleeding. This is because a failure occurs.

[0062]

Next, the master of the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples. In addition, all the parts shown below are based on weight.

Example 1 4.0 parts of polyvinyl butyral (PVB4000-1 manufactured by Denki Kagaku Kogyo KK) was dissolved in 33.6 parts of methanol. 2.2 parts of water was slowly added to this solution with stirring to obtain a slightly cloudy coating solution. This was placed in an atmosphere of 20 ° C. and 50% RH to a thickness of 2.
After drying with a wire bar on a 0 μm biaxially stretched polyester film, the mixture was uniformly coated so that the adhesion amount was 7.0 g / m ^2, and dried in a drying box at 50 ° C. for 3 minutes to form a porous resin film. Paste cellophane tape on the surface of this porous resin film, peel off the porous resin film from the film,
When the ink protruded from the cellophane tape was placed on paper and applied with ink, the ink did not adhere to the paper. Therefore, the existence of a thin film was recognized. The thickness of the thin film measured from the SEM photograph was about 0.4 μm.

On the surface opposite to the surface where the porous resin film is formed, a mixture of silicon and a cationic antistatic agent is used to prevent the hot-melted film from sticking to the thermal head and to prevent static electricity. Was applied so that the adhesion amount after drying was 0.05 g / m ² .
Subsequently, 1 part of vinyl chloride / vinyl acetate copolymer (VYHH manufactured by Union Carbide Co., Ltd.) 2 parts of polyester fiber (0.15 denier manufactured by Teijin Limited, 4 μm in diameter with a specific gravity of 1.4) 8 parts of ethyl acetate Disperse the mixture well in a ball mill to a thickness of 1.5
Using a roll coater, the polyester film having a thickness of 3.5 μm was applied to a dry adhesion amount of 3.5 g / m ² to form a porous fiber membrane. The drying temperature was 50 ° C. The obtained porous fiber membrane was peeled from the polyester film, and a polyethylene-based adhesive was applied to the porous fiber membrane at 3 g / m ² ,
The surface was laminated on a porous resin film to obtain a thermosensitive stencil master.

Example 2 4.0 parts of polyvinyl butyral (manufactured by Denki Kagaku Kogyo Co., Ltd., PVB4000-1) 4.0 parts Methanol 33.6 potassium titanate whisker (Tofica Y, manufactured by Otsuka Chemical Co., Ltd.) 0.8 The mixture was dispersed and mixed in a ball mill, and 2.3 parts of water was added with slow stirring to obtain a cloudy coating solution. This was uniformly applied so as to have an adhesion amount of 7.0 g / m ² after drying in the same manner as in Example 1 to form a porous resin film. The thickness of the thin film was about 0.4 μm. Thereafter, in the same manner as in Example 1, stick prevention processing was performed, and a porous fiber film was formed on the porous resin film to obtain a thermosensitive stencil printing master.

(Comparative Example 1) A porous resin film was formed in the same manner as in Example 1 except that the amount of water was changed to 2.8 parts, and thereafter, an opening area ratio sample was prepared. The presence or absence of a thin film was tested in the same manner as in Example 1, but the ink adhered to the paper and no thin film was observed. Printing is PRIPO
Tested using the RT VT 3820 system.

(Comparative Example 2) A porous resin film was formed on a polyester film in the same manner as in Example 1 except that a thin film was not formed, and a master for heat-sensitive stencil printing was obtained.

The masters obtained in the above Examples and Comparative Examples were evaluated. The results were as shown in Table 1.

Punching sensitivity: も の indicates that the film portion of the master was perfectly punctured by the thermal head, を indicates that the piercing was performed, but partially reduced the piercing diameter, and △ indicates that the piercing was not partially perforated. Indicated by Print density: NBS paper manufactured by NBS Ricoh Co., Ltd. was used as print paper, and the 20th sheet was measured with a Macbeth densitometer at a third printing speed. Printing unevenness: Observing the printed image with the naked eye,
All density irregularities are current masters (VT-2 manufactured by Ricoh Company).
The master is marked with ◎, the one slightly better than the current master is marked with ○, and the one equivalent to the current master is marked with △. Set-off: Observation of the printed matter with the naked eye, ◎: very good than the current master (manufactured by Ricoh, VT-2 master), ○: slightly better than the current master, ○: equivalent to the current master , Print elongation: After printing 1000 sheets, ◎ indicates no master elongation, Δ indicates film peeling, and × indicates elongation.

[0070]

[Table 1]

The samples of Examples 1 and 2 were PRIPO.
After printing 200 sheets using the RT VT 3820 system, the film was deliberately broken on the plate cylinder and the residue was manually removed from the plate cylinder, but the film and the porous resin film did not peel off. On the other hand, in the sample of Comparative Example 1, the film and the porous resin film were peeled off. In Comparative Example 2, the porous resin film was peeled off, and printing elongation occurred. The samples of Examples 1 and 2 had high stiffness and were satisfactory in transportation by the test printing machine.

(Examples 3 to 8) Polyvinyl acetal resin (manufactured by Sekisui Chemical Co., Ltd., Eslek KS-1) 3.2 parts Talc (manufactured by Nippon Talc, Microace LG) 2.4 parts Sorbitan fatty acid ester ( Nikko Chemicals, SO-10) 0.1 part Modified silicone oil (KF6012, Shin-Etsu Chemical Co., Ltd.) 0.1 part Acrylic polymer O / W emulsion (Joncryl-711, Johnson Polymer) 0.2 part The above was dissolved and dispersed in ethyl acetate, and added to water (HEC
(1% solution) was slowly added with stirring to obtain a coating liquid for forming a cloudy porous resin film. Ethyl acetate and water (HEC
The amount of (1% solution) depends on the solid content concentration (SC) of each coating solution shown in Table 2, and the ratio of both is 1.5 for ethyl acetate and 1.0 for water (HEC 1% solution). . Each of the above coating solutions was applied on a 2.0 μm-thick biaxially stretched polyester film by a die head in an atmosphere of 20 ° C. and 50% RH so that the adhesion amount after drying became the value shown in Table 2. ° C
Drying was performed in a 50% RH atmosphere to form a porous resin film.
The thickness of the thin film was about 0.4 μm. After the formation of the porous resin film, a porous fiber film and a porous film were laminated on the porous resin film in the same manner as in Example 1.

Formulation of anti-fusing agent coating liquid Silicone oil (SF8422 manufactured by Shin-Etsu Chemical Co., Ltd.) 0.5 parts Surfactant (Plysurf A208 manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) 0.5 parts Toluene 100.0 parts The anti-fusing agent coating solution is applied to the surface of the thermoplastic resin film opposite to the porous resin film by using a bar coater so that the adhesion amount after drying is about 0.05 g / m ² , A stencil master was obtained.

The masters of Examples 3 to 8 obtained above were used as stencil printing machine reports JP1300 JP5050 VT6.
The plate making and printing were performed at 000, respectively, and the image after printing 10 sheets was examined. In addition, Table 2 and FIG. 4 show the evaluation of the thermosensitive stencil master. In the printed images of Table 2, ○ indicates good, Δ indicates slight white spots, and × indicates bad.
As shown in FIG. 4, the porosity of the porous resin film is (−0.00
In the case of 63D + 61)% or more, good results were obtained for the printed image.

<Evaluation> (A) Porous resin film void area ratio The porous resin film of the master was placed on the film side with an optical microscope (Olympus BX60, magnification 20; Olympus BX60 magnification).
0 times. Lighting is reflected light, level 9. The polarizing filter is used at the position where the sharpness is most effective. ) Observe and capture images into a computer. Focus on the surface of the porous resin film. (The sample is brought closer to the eyepiece of the optical microscope, and the part of the porous resin film that is focused first)
The image is binarized using the image processing software “WinROOF” (manufactured by Mitani Corporation) to determine the void area ratio.
The binarization procedure is as follows. Gray imaging, density conversion (default), automatic binarization (P tile method, default), filling in, deleting (100 or less), measurement (one area of shape feature). In the case of a master in which a porous fiber membrane is laminated on a porous resin membrane, in the step of creating the master,
Before laminating the porous fiber membrane, take a photograph from the side without the film.

(B) Film perforated area The film perforated area of the master was observed with an optical microscope (Olympus, Olympus BX60 magnification: 200 times; illumination was reflected light, level 9. A polarizing filter was used at the position where sharpness was most effective). Capture images to computer.
The image is binarized using the image processing software “WinROOF” (manufactured by Mitani Corporation) to determine the void area ratio.
The binarization procedure is as follows. Gray image conversion, density conversion (default), automatic binarization (P tile method, default), filling in, deletion (500 or less), measurement (shape feature-
area).

[0077]

[Table 2]

[0078]

According to the present invention, it is possible to obtain a master having a high stiffness and a large adhesive strength while maintaining excellent image quality and a small set-off characteristic, a heat-sensitive stencil printing apparatus using the master, and a heat-sensitive stencil printing method. Was. Further, according to the present invention,
Since the thin film was formed in contact with the film surface, the stiffness of the film was increased, and a highly smooth film surface could be formed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a porous resin film formed of an aggregate of many cells having a ceiling.

FIG. 2 is a cross-sectional view of a porous resin film formed of a foam film formed of an aggregate of open-cell cells.

FIG. 3 is a cross-sectional view of a porous resin film formed of an aggregate-like film formed by adhering granular or fibrous resins.

FIG. 4 is a diagram showing a relationship between a perforated area of a thermoplastic resin film and a porosity of a porous resin film.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermoplastic resin film 4 Porous resin film 4a Void of porous resin film 4b Constituent element constituting porous resin film 7 Porous fiber film 8 Thin film

Claims (10)

[Claims] 1. A thermoplastic resin film having a porous resin film on a surface thereof, a porous fiber film made of a fibrous substance laminated thereon, and a thin film formed on the film side of the porous resin film. A master for heat-sensitive stencil printing, wherein the master is formed in close contact with a stencil. 2. The range of the porosity of the porous resin film in contact with the thermoplastic resin film through the thin film with respect to the perforated area D of the thermoplastic resin film is (−0.0063D + 61)% or more (D ≧ 314 μm ² ). Claim 1 characterized by the following:
The heat-sensitive stencil master described. 3. The porous resin film is formed by using a synthetic resin solution in which a synthetic resin is solubilized by mixing a synthetic resin with a plurality of solvents having different solubilities. Or the master for heat-sensitive stencil printing according to 2. 4. The master for heat-sensitive stencil printing according to claim 1, wherein the thin film contains a resin component of the porous resin film. 5. The method according to claim 1, wherein the porous resin film and the thin film are formed in a single film forming step.
The master for heat-sensitive stencil printing according to any one of the above. 6. The film according to claim 1, wherein the thin film is broken together with the thermoplastic resin film at the time of thermal perforation of the thermoplastic resin film to form a hole through which ink passes. Heat-sensitive stencil master. 7. A thermoplastic resin film having an open area ratio of 20
% Or more, when the air permeability is 2.0 to 160 cm
^The master for heat-sensitive stencil printing according to any one of claims 1 to 6, wherein the master is ³ / cm ² · sec. 8. The master for heat-sensitive stencil printing according to claim 1, wherein two or more porous fiber membranes made of fibers are laminated. 9. A plate making device for making a master by subjecting the master according to claim 1 to heat melting and perforation, and a plate cylinder around which the master made is wound.
A heat-sensitive stencil printing machine comprising at least an ink supply mechanism provided inside the plate cylinder, and a pressing device for pressing a printing sheet against the master wound around the outer peripheral surface of the plate cylinder. . 10. A process for making a master by heat-melting and punching the master according to claim 1, and a process of winding the master made on a plate cylinder provided with an ink supply mechanism inside. And a step of pressing printing paper against the master wound around the outer peripheral surface of the plate cylinder by a pressing device.