JP2003011542A - Base paper for thermal mimeographic printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a base paper for thermal mimeographic printing in which a thermoplastic resin film and a porous support of thermoplastic resin fibers are laminated and which is excellent in image clearness, printing resistance, and conveyance properties and solves not only a trouble caused by the falling of fibers but also the problem of the hindrance of the passage of ink by the free ends of the thermoplastic resin fibers. SOLUTION: The number of the free ends of the thermoplastic resin fibers forming the porous support is controlled to be one per mm<2> or below.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a halogen lamp,
The present invention relates to a heat-sensitive stencil printing base paper which is perforated by flash light irradiation such as a xenon lamp or a flash bulb, infrared irradiation, pulsed irradiation such as a laser beam, or a thermal head.

[0002]

2. Description of the Related Art Conventionally, a heat-sensitive stencil printing base paper (hereinafter sometimes simply referred to as "base paper") comprises a thermoplastic resin film such as a polyester film or a vinylidene chloride film and a natural fiber such as Manila hemp. There is known a thin paper, a thin paper obtained by mixing natural fibers and synthetic fibers, or a structure in which a porous support composed of a thin paper consisting only of synthetic fibers is bonded with an adhesive (for example, JP-A-57-182495, JP-A-59
-115898 and Japanese Patent Laid-Open No. 03-8892).

Among the above-mentioned materials, the conventional heat-sensitive stencil printing base paper containing natural fibers changes in strength and rigidity due to changes in the environment in which it is used, especially humidity, and in high-humidity environments, wrinkles occur during transport due to decreased rigidity. There was a problem such as occurrence of. Also, when printing a large number of sheets,
There is a problem that the strength of the porous support decreases due to the water contained in the printing ink, and the printed image is elongated due to the stress caused by printing. On the other hand, the heat-sensitive stencil printing base paper using a porous support made of 100% synthetic fibers is expensive, but it can solve the problems found in the conventional heat-sensitive stencil printing base paper containing natural fibers. Are known.

It is generally known that the porous support used in these conventional heat-sensitive stencil printing base papers is produced by wet-making papermaking with short fibers having a fiber length of about 1 to 15 mm. There are various binding methods for these fibers,
Reinforcing processing with a binder resin is used in a porous support containing natural fibers, and binder fibers are used in a porous support consisting of only synthetic fibers, and it is possible to obtain a certain degree of interfiber bonding force by these methods. There is. However, in the process in which the base paper is transported in the printing machine, the fibers fall off from the base paper due to the frictional force of the transport rolls and platen rolls, etc.The fibers that have fallen off are accumulated in the printing machine as the usage amount increases, and However, there remains a problem that the ink may fly between the base papers to cause a plate-making defect, or may adhere to the plate after the plate-making to impede the passage of ink.

As a method that does not use short fibers, a non-woven fabric by a melt blow method is known. For example, Japanese Patent Laid-Open No. 05-1
Japanese Patent Publication No. 79554 discloses a method for producing a nonwoven fabric in which a thermoplastic resin is melted, extruded from a nozzle, finely collected by a heating gas flow, collected, and then stretched in at least one direction. Further, for heat-sensitive stencil printing, since mechanical strength that can withstand printing is required, JP-A-08-60515 and JP-A-11-139020 disclose a manufacturing method by biaxial stretching. In addition, JP-A-6-30527
Japanese Patent Publication No. 3 discloses that a base paper is obtained by co-stretching an unstretched polyester film and a non-woven fabric made of unstretched polyester fibers collected by a melt blow method. The base paper is obtained by adhering a polyester film and a polyester non-woven fabric without an adhesive, and has the characteristic that the printing clarity is excellent because no adhesive is used.

However, an unstretched part may remain in the non-woven fabric obtained by stretching after being collected by these melt blow methods, and when used for heat-sensitive stencil printing, if the unstretched part is large, the unstretched part becomes white during printing. There was a case where it was omitted and became a fatal defect. That is, when a fiber is extruded by melt blow on the assumption that it is drawn, the fiber diameter is set to be thicker than a desired fiber diameter in an unstretched state. Therefore, when a fiber is cut from the nozzle, a break occurs and the fiber becomes thicker. When the tip of the cut portion of the fiber is not bonded to another fiber (referred to as a free end), the fiber is not substantially stretched, which becomes a cause of impeding ink passage.
Therefore, if there are many free ends, it becomes difficult to use as a base paper for heat-sensitive stencil printing.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a heat-sensitive stencil printing base paper obtained by laminating a thermoplastic resin film and a porous support made of thermoplastic resin fibers. An object of the present invention is to provide a heat-sensitive stencil printing base paper which is excellent in image sharpness, printing durability, and transportability, and which solves the problems caused by fiber dropout and the problem of blocking the ink passage due to the free end of the thermoplastic resin fiber. .

[0008]

The above object of the present invention can be achieved by the following means. That is, according to the present invention, firstly, in claim 1, there is provided a heat-sensitive stencil printing base paper obtained by laminating a thermoplastic resin film and a porous support made of a thermoplastic resin fiber, Provided is a heat-sensitive stencil printing base paper characterized in that the number of free ends of the thermoplastic resin fibers constituting the support is 1 / mm ² or less.

Secondly, according to a second aspect, in the heat-sensitive stencil printing base paper according to the first aspect, the thermoplastic resin film and the porous support made of the thermoplastic resin fiber are thermocompression bonded. A heat-sensitive stencil printing base paper is provided.

Thirdly, in claim 3, the heat-sensitive stencil printing base paper according to claim 1 or 2, wherein the thermoplastic resin film is a polyester resin film is provided. To be done.

Fourth, in claim 4, the above-mentioned claims 1, 2
Alternatively, in the heat-sensitive stencil printing base paper described in 3, the heat-sensitive stencil printing base paper is provided in which the thermoplastic resin fiber is a polyester resin fiber.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below.
As described above, in the heat-sensitive stencil printing base paper of the present invention, the number of free ends of the thermoplastic resin fibers constituting the porous support is 1 /
It is characterized by being less than or equal to mm ² . As shown in FIG. 1, the above-mentioned "free end" refers to the end of one fiber that is bonded to only one end side of the fiber and is not bonded to the other fiber of the other side. When the number of free edges is more than 1 / mm ² , white spots are conspicuous especially when solid printing is performed, and character chips occur when a character image is printed. The number of free ends is preferably 1 / mm ² or less, more preferably 0.5 / mm ² or less, still more preferably 0.
1 piece / mm ² or less. Further, it is not necessary to consider the size of the free end that does not affect the ink passage, and the size of the maximum width of about 15 μm or more is a problem.

The thermoplastic resin fibers constituting the porous support in the present invention include polyesters such as polyethylene terephthalate and polyethylene naphthalate, and
Examples thereof include polyolefins such as polyethylene and polypropylene, and polyamides such as polyphenylene sulfide, nylon 6 and nylon 66. In the present invention, among them, thermoplastic fibers made of polyester are most preferable from the viewpoint of spinnability, strength and elongation characteristics and the like.

The basis weight of the porous support made of the thermoplastic resin fiber of the present invention is preferably 2 to 20 g / m ² ,
More preferably 3 to 15 g / m ² , particularly preferably 5
To 10 g / m ² . When the grammage is 2 to 20 g / m ² , the ink permeability is good and the imageability and printability are good. When the basis weight is 5 to 20 g / m ² , more sufficient strength can be obtained.

The average fiber diameter of the thermoplastic fibers constituting the porous support of the present invention is preferably 1 to 15 μm, more preferably 2 to 10 μm, and particularly preferably 2
To 6 μm. When the average fiber diameter is 1 to 15 μm, sufficient strength and heat resistance are obtained, ink permeability is good, and white spots do not occur during printing, which is preferable.

The porous support made of thermoplastic resin fibers of the present invention is preferably a porous support made of stretched thermoplastic fibers from the viewpoint of mechanical strength and heat resistance.

As the thermoplastic resin film in the present invention, conventionally known ones such as polyester, polyamide, polypropylene, polyethylene, polyvinyl chloride, polyvinylidene chloride or copolymers thereof may be used, but from the viewpoint of perforation sensitivity. A polyester film is particularly preferably used.

The polyester used in the polyester film is preferably polyethylene terephthalate, a copolymer of ethylene terephthalate and ethylene isophthalate, a copolymer of hexamethylene terephthalate and cyclohexane dimethylene terephthalate, and the like. Particularly preferred for improving the perforation sensitivity are a copolymer of ethylene terephthalate and ethylene isophthalate, a copolymer of hexamethylene terephthalate and cyclohexane dimethylene terephthalate, and the like.

In the thermoplastic resin film of the present invention, if necessary, an organic lubricant such as a flame retardant, a heat stabilizer, an antioxidant, an ultraviolet absorber, an antistatic agent, a pigment, a dye, a fatty acid ester or a wax, or a polysulfate. An antifoaming agent such as siloxane can be blended.

Further, slipperiness can be imparted if necessary. The method for imparting slipperiness is not particularly limited, but examples thereof include clay, mica, titanium oxide, calcium carbonate, kaolin, talc, inorganic particles such as wet or dry silica, organic particles containing acrylic acid, styrene and the like as constituent components. And the like, a method using internal particles, a method of applying a surfactant, and the like.

The thickness of the thermoplastic resin film in the present invention is usually preferably 0.1 to 5.0 μm, more preferably 0.1 to 3.0 μm. Thickness is 5.
If it exceeds 0 μm, the perforation property may decrease, and
If the thickness is less than μm, film forming stability may be deteriorated or printing durability may be deteriorated.

In the present invention, the polyester film is
For example, it can be manufactured by the T-die extrusion method. This is a method of producing a polyester film by extruding polyester onto a cast drum, and by adjusting the slit width of the die, the discharge amount of the polymer, and the number of revolutions of the cast drum, a polyester film having a desired thickness can be obtained. It can be manufactured.

In the present invention, the porous support made of polyester fiber is obtained by using a nonwoven fabric produced by a direct melt spinning method such as a melt blow method.

In the melt-blowing method, when a melted polymer is discharged from a plurality of orifices arranged in a row in a mouthpiece, a nonwoven fabric made of polyester fiber is blown with hot air from slits provided on both sides of the row of orifices. The polymer discharged is made finer and then sprayed on a net conveyor arranged at an appropriate position to collect and form a web. Since the polyester fiber is rapidly cooled from a molten state to a room temperature atmosphere, it solidifies in a state close to an amorphous state, is finely densified by the pressure of hot air, but is not stretched, and is in a so-called non-oriented state. Further, the fibers are collected in a state of being fused to each other, and by appropriately adjusting the collection distance between the die and the net conveyor, the degree of fusion of the fibers can be adjusted, the polymer discharge amount, the hot air temperature, the hot air. The basis weight and fiber diameter of the non-woven fabric can be arbitrarily set by appropriately adjusting the flow rate, the conveyor moving speed, and the like.

The non-woven fabric thus obtained is not uniform in fiber diameter, but is composed of fibers in which thick fibers and thin fibers are well dispersed. In order to set the number of free ends due to breakage during polymer extrusion of the present invention to 1 or less per mm ² , it is achieved by appropriately adjusting the viscosity at the time of polymer discharge, polymer discharge rate, hot air temperature, hot air flow rate, etc. it can.

In the heat-sensitive stencil printing base paper of the present invention, adhesion between the thermoplastic resin film and the porous support made of thermoplastic fibers is performed by using a vinyl acetate resin, an acrylic resin, a urethane resin, a polyester resin, or the like. An adhesive may be used, but from the viewpoint of printing clarity, it is preferable to adhere without using an adhesive. The method of adhering without the use of an adhesive is not particularly limited, but a method of superposing a thermoplastic resin film and a porous support made of thermoplastic fibers and thermocompression-bonding is preferable.

The method of thermocompression bonding of the porous support comprising the thermoplastic resin film and the thermoplastic fibers in the present invention is not particularly limited, but thermocompression bonding with a heating roll is particularly preferable from the viewpoint of process ease. preferable. In the present invention, thermocompression bonding can also be performed by superposing a biaxially stretched thermoplastic resin film and a porous support made of stretched thermoplastic resin fiber, but after casting the thermoplastic resin film, before the stretching step. It is preferable that the porous supports made of thermoplastic resin fibers in an unstretched state are superposed at the stage. The thermocompression bonding temperature is preferably between 50 ° C. and the glass transition temperature (Tg) + 20 ° C. of the thermoplastic fiber. Next, the thermocompression-bonded thermoplastic resin film and the unstretched nonwoven fabric made of thermoplastic fibers are co-stretched. By co-stretching in the thermocompression bonded state, the film and the porous support can be integrally stretched. Further, by co-stretching the both together, the porous support made of thermoplastic fibers serves as a reinforcing body, and the thermoplastic resin film can be formed extremely stably without tearing. In the present invention, the above-mentioned “co-stretching” means that the unstretched non-woven fabric is laminated with a film and then both are subjected to stretching together.

The co-stretching method in the present invention is preferably biaxial stretching from the viewpoint of improving the perforation sensitivity of the film and the uniform dispersibility of the fibers forming the porous support made of thermoplastic fibers. The biaxial stretching may be either a sequential biaxial stretching method or a simultaneous biaxial stretching method. In the case of the sequential biaxial stretching method,
Stretching is generally performed in the longitudinal direction and then in the transverse direction, but the stretching may be reversed. The stretching temperature includes the glass transition temperature (Tg) and the temperature rising crystallization temperature (Tc) of the thermoplastic fiber used for stretching.
It is preferably between c). The draw ratio is not particularly limited, and is appropriately determined depending on the type of the polymer for the thermoplastic resin film used, the perforation sensitivity required for the heat-sensitive stencil printing base paper, etc. is there. Further, after biaxial stretching, it may be re-stretched vertically or horizontally or vertically and horizontally. Furthermore, it is also preferable to subject the heat-sensitive stencil printing base paper of the present invention to a heat treatment after biaxial stretching. The heat-sensitive stencil printing base paper obtained by the treatment may be once cooled to about room temperature and then aged at a relatively low temperature of 40 to 90 ° C. for about 5 minutes to 1 week. When such aging is adopted, curl during storage of the heat sensitive stencil printing paper or in the printing machine,
It is particularly preferable because wrinkles do not occur.

The base paper for heat-sensitive stencil printing of the present invention has a silicone oil, a silicone resin, a fluorine resin, a surfactant, an antistatic agent, in order to prevent fusion during punching on one surface of the film to be brought into contact with the thermal head. Agents, heat-resistant agents, antioxidants, organic particles, inorganic particles, pigments, dispersion aids, preservatives,
It is preferable to provide a thin layer of an antifoaming agent or the like. The thickness of the fusion preventing thin layer is preferably 0.005 to 0.4 μm.
m, more preferably 0.01 to 0.4 μm.

When a thin layer for preventing fusion is provided in the heat-sensitive stencil printing base paper of the present invention, the coating liquid is applied in the state of a coating liquid dissolved, emulsified or suspended in water, and then the water is removed by drying or the like. Is preferred. The coating may be performed at any stage before or after stretching the film. In order to express the effect of the present invention more remarkably, in the case of performing sequential biaxial stretching such as transverse stretching after longitudinal stretching, before transverse stretching,
When simultaneous biaxial stretching is performed, it is particularly preferable to apply the coating before stretching. The coating method is not particularly limited, but it is preferable to use a roll coater, a gravure coater, a reverse coater, a bar coater or the like. In addition, before applying a thin layer for fusion prevention, if necessary, in air on the coated surface,
Alternatively, activation treatment such as corona discharge treatment may be performed in various atmospheres.

<Characteristics Measuring Method> (1) Number of Free Ends: Arbitrary 10 excluding end parts of sample
Photographing 0 places with an electron microscope at a magnification of 200 times (effective image area of photograph 80 mm × 110 mm = actual photographed area 0.242 mm ² ) and the number of free edges with respect to the total image area of 100 sheets is “piece / mm”. Calculated as ² ".

(2) Average fiber diameter: The average fiber diameter is determined by taking 10 photographs of any 10 positions of the porous support with an electron microscope at a magnification of 500, and selecting 10 of each photograph.
The diameter of each fiber was measured, and this was carried out on 10 photographs. The total 100 fiber diameters were measured and the average value thereof was expressed.

(3) Loss of fiber evaluation: Heat sensitive stencil printing base paper was supplied to Preport VT6000 manufactured by Ricoh Co., Ltd.
250 charts with 6-point letters
Plate making was performed and the presence or absence of fibers adhering to the platen roll was observed.

(4) Image quality evaluation: Image quality evaluation was carried out continuously after the above fiber drop-off evaluation was completed. The evaluation method was based on Ricoh's Preport VT6000
, A chart having black solids and 6-point English letters was made as a document, and 100 sheets were printed 10 times at standard speed. For each of the 50th image, 10 sheets, the uniformity of the solid black portion and the chipping of English letters were visually observed, and judged as follows. “○” indicates that there were no white spot defects on the solid black portion, and “△” indicates that there were no white spots on the solid black portion but there was no character chipping, and there were many white spot defects. , "×" was used for the English characters that could not be read easily. After the evaluation of each heat-sensitive stencil printing base paper, each roll in the plate making section of the printing press and the carrying process were cleaned with a cloth moistened with alcohol and the following tests were carried out.

[0035]

EXAMPLES Next, the present invention will be described in more detail by way of examples. However, the present invention is not limited to the following examples.

Example 1 Using a rectangular spinneret having a hole diameter of 0.35 mm, 100 holes, and one row of orifices, the spinneret temperature was 280 ° C., and the discharge rate was 30.
g / min, polyethylene terephthalate raw material (melting point = 2
(54 ° C.) was spun by a melt blow method, and the fibers were collected on a conveyor to prepare an unstretched nonwoven fabric made of polyester fibers having a basis weight of 100 g / m ² . The average fiber diameter of the polyester fibers constituting the obtained non-woven fabric was about 20 μm. Next, the nonwoven fabric sheet was stretched 3.5 times in the longitudinal direction between heating rolls at 85 ° C., then stretched 4.0 times in the width direction at 90 ° C. with a tenter type stretching machine, and further heated at a temperature of 16
Heat treatment was performed at 0 ° C. to obtain a porous support having an average fiber diameter of 10.2 μm and a basis weight of 7.1 g / m ² .

Example 2 An unstretched polyester film was produced by the T-die extrusion method, and the basis weight obtained in Example 1 was 100 g /
It was superposed on an unstretched nonwoven fabric of m ² , supplied to a heating roll and thermocompression-bonded at a roll temperature of 85 ° C. to prepare a laminated sheet. Next, the laminated sheet was stretched 3.5 times in the longitudinal direction between heating rolls at 85 ° C., and then 90 times with a tenter type stretching machine.
The film was stretched 4.0 times in the width direction at 0 ° C., further heat-treated at a temperature of 160 ° C., and a water-soluble release agent was applied to the film surface to prepare a heat-sensitive stencil printing base paper. The obtained porous support had a basis weight of 7.0 g / m ² and a film thickness of 1.5 μm. The evaluation results are shown in Table 1.

Comparative Example 1 Using a rectangular spinneret having a hole diameter of 0.35 mm, 100 holes, and a single row of orifices, the spinneret temperature was 320 ° C. and the discharge rate was 30.
g / min, polyethylene terephthalate raw material (melting point = 2
(54 ° C.) was spun by a melt blow method, and the fibers were collected on a conveyor to prepare an unstretched nonwoven fabric made of polyester fibers having a basis weight of 100 g / m ² . The average fiber diameter of the polyester fibers constituting the obtained non-woven fabric was about 20 μm. The non-woven fabric sheet was stretched 3.5 times in the longitudinal direction between heating rolls at 85 ° C. and then 90
It is stretched 4.0 times in the width direction at ℃, and further heat-treated at a temperature of 160 ℃, average fiber diameter 10.2μm, basis weight 7.1g
A porous support of / m ² was obtained. The porous support and a biaxially stretched polyester film having a thickness of 1.5 μm were bonded with a vinyl acetate adhesive, and a water-soluble release agent was applied to the film surface to prepare a heat-sensitive stencil printing base paper. The evaluation results are shown in Table 1.

Comparative Example 2 40% by mass of unstretched polyester fiber having a fineness of 0.2 decitex and a fiber length of 3 mm and 60% by mass of polyester binder fiber having a fineness of 1.5 decitex and a fiber length of 5 mm were mixed, and a wet papermaking method was used. A porous support having an amount of 8.5 g / m ² was obtained. The porous support and a biaxially stretched polyester film having a thickness of 1.5 μm were bonded with a vinyl acetate adhesive, and a water-soluble release agent was applied to the film surface to prepare a heat-sensitive stencil printing base paper. The evaluation results are shown in Table 1.

[0040]

[Table 1]

[0041]

As described above, according to the heat-sensitive stencil printing base paper of claim 1, the number of free ends of the thermoplastic resin fibers constituting the porous support is 1 / mm ² or less. In addition to the unprecedented obstacles to ink passage due to fiber drop, which also solves the problems of ink passage obstruction due to the free ends of thermoplastic resin fibers, it is possible to solve the problems of printing sharpness, running stability, and printing durability. At the same time, it is possible to obtain a base paper satisfying

According to the heat-sensitive stencil printing base paper of claim 2,
Since the thermoplastic resin film and the porous support made of thermoplastic resin fibers are thermocompression bonded, the problem of clogging between the fibers due to the adhesive is avoided, and thus the ink-permeability excellent stencil printing base paper Can be obtained.

According to the heat-sensitive stencil printing base paper of claim 3,
Since the thermoplastic resin film is a polyester resin film, a heat-sensitive stencil printing base paper having excellent perforation sensitivity can be obtained.

According to the heat-sensitive stencil printing base paper of claim 4,
Since the thermoplastic resin fiber is a polyester resin fiber, to obtain a heat-sensitive stencil printing base paper having a porous support of a nonwoven fabric composed of a thermoplastic resin fiber having excellent spinnability, strength and elongation characteristics, etc. You can

[Brief description of drawings]

FIG. 1 is a view showing an enlarged photograph by an electron microscope showing an example of free ends of thermoplastic resin fibers constituting a porous support.

[Explanation of symbols]

10 Free end

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroshi Tateishi             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh (72) Inventor Kazuyo Mizuno             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh (72) Inventor Susumu             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh (72) Inventor Takehiro Saito             Miyame Prefecture Shibata-cho Shibata-cho Large name Nakamei student character Shinmeidou 3             Address No. 1 Tohoku Ricoh Co., Ltd. (72) Inventor Yoshihiro Mimura             Miyame Prefecture Shibata-cho Shibata-cho Large name Nakamei student character Shinmeidou 3             Address No. 1 Tohoku Ricoh Co., Ltd. F-term (reference) 2H114 AB23 AB25 BA05 BA10 DA56                       DA73 DA76 EA01 EA02 FA01                       FA06                 4L047 AA21 BA23 CA06 CA19 CB10                       CC08 DA00

Claims (4)

[Claims] 1. A base paper for heat-sensitive stencil printing, comprising a thermoplastic resin film and a porous support made of thermoplastic resin fibers laminated together, wherein the thermoplastic resin fibers constituting the porous support have free ends. The heat-sensitive stencil printing base paper is characterized in that the number is 1 / mm ² or less. 2. The heat-sensitive stencil printing base paper according to claim 1, wherein a thermoplastic resin film and a porous support made of a thermoplastic resin fiber are thermocompression bonded. 3. The base paper for heat-sensitive stencil printing according to claim 1 or 2, wherein the thermoplastic resin film is a polyester resin film. 4. The heat-sensitive stencil printing base paper according to claim 1, wherein the thermoplastic resin fiber is a polyester resin fiber.