JPH07205564A - Thermal mimeographing base paper and manufacture thereof - Google Patents

Abstract

PURPOSE:To improve vividness of images and prevent generation of offset by a method wherein a porous support body made of a thermoplastic resin fiber having predetermined aperture face integration ratio and aperture average diameter is layered on a thermoplastic resin film. CONSTITUTION:A porous support body consisting of a thermoplastic resin fiber such as a polyester and having 5-80% of aperture face integration ratio and 5-100mum of aperture average diameter is layered on a thermoplastic resin film such as the polyester so as to form a thermal mimeographing base paper. In the thermoplastic resin fiber, a flame retarder, a heat stabilizer, an antioxidant, and an ultraviolet absorbent can be mixed. When the aperture face integration ratio is 5% or lower, ink permeability is low. When it is 80% or higher, ink retentive property lowers. When the average diameter is 5mum or less, the ink permeability is low, and the ink retentive property lowers when the average diameter is 100mum or more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive stencil sheet which is perforated by a halogen lamp, a xenon lamp, a flash bulb or the like, flash irradiation or infrared irradiation, pulsed irradiation such as a laser beam, or a thermal head, and its production. It is about the method.

[0002]

2. Description of the Related Art As a base paper for heat-sensitive stencil used in heat-sensitive stencil printing, a thermoplastic resin film such as polyester film, vinylidene chloride film or polypropylene film, and thin paper, non-woven fabric, screen made of natural fiber or synthetic fiber are used. A structure having a structure in which a porous support made of gauze or the like is bonded with an adhesive is known (JP-A-51-2512, JP-A-57-57).
182495, JP-A-58-147396, JP-A-59-15898 and the like).

However, these conventional heat-sensitive stencil sheets are not always satisfactory in terms of the clarity of printed images.

The heat-sensitive stencil printing referred to in the present invention means that the film of the heat-sensitive stencil sheet is melted and perforated by the above-mentioned thermal head or the like in accordance with the characters and figures of the printing original to prepare a master, and the master is supported Printing ink is supplied from the body side so that the ink permeates through the perforated portion of the film, and printing is performed on the printing paper in contact with the film surface of the master.

There are various possible reasons why the image clarity of a printed matter using a conventional heat-sensitive stencil sheet is not sufficient.
One of them is due to the fibers constituting the support. For example, thin paper made of natural fibers, which has been used most often in the past, has thick and uneven fibers, resulting in uneven ink permeability, faint printing, and film perforation. There were drawbacks such as white spots in solid printing due to the fibers present in the part.

In order to improve these drawbacks, a heat-sensitive stencil sheet made of a paper or non-woven fabric mainly made of synthetic fibers such as polyester fibers and polypropylene fibers is used for the purpose of making the thickness of the fibers of the support thin or uniform. A base paper has been proposed. At the same time, measures are taken such as reducing the basis weight of the support fibers as much as possible (Japanese Patent Laid-Open Nos. 59-2896, 59-16793, and 2-67).
197 publication).

However, the paper-making papers and non-woven fabrics mainly composed of these synthetic fibers have improved image sharpness as compared with thin papers made of natural fibers, but they have not been sufficiently satisfactory. In reality, the demand for higher-definition printed images has not been sufficiently met.

Furthermore, when the basis weight of the support fiber is reduced, there is a drawback that the set-off is likely to occur when printed matter is piled up.

[0009]

SUMMARY OF THE INVENTION The present invention is intended to solve the above problems and to provide a heat-sensitive stencil sheet which is excellent in the sharpness of a printed image and does not show through.

[0010]

In order to achieve the above object, the inventors of the present invention have conducted extensive studies on the function of the support of the heat-sensitive stencil sheet and the mechanism of ink leaching. It has been found that the defects of the conventional stencil sheet for conventional heat-sensitive stencil can be improved by optimizing the properties and completed the present invention. That is, the present invention is a base paper for heat-sensitive stencil comprising a thermoplastic resin film and a porous support made of thermoplastic resin fibers laminated thereon, and the porous support has an open area ratio of 5 to 80%. The present invention relates to a stencil sheet for heat-sensitive stencil and a method for producing the stencil sheet, which has an average aperture diameter of 5 to 100 μm.

The thermoplastic resin film in the present invention is
For example, conventionally known materials such as polyester, polyamide, polypropylene, polyethylene, polyvinyl chloride, polyvinylidene chloride or copolymers thereof are used, and polyester film is particularly preferably used from the viewpoint of perforation sensitivity.

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.

The thermoplastic resin film in the present invention is
Usually, it is preferably stretched, and can be produced by a conventionally known T-die method, inflation method, or the like. For example, in the T-die method, an unstretched film can be produced by extruding a polymer onto a cast drum, then longitudinally stretched by a heating roll group, and if necessary, supplied to a tenter or the like for lateral stretching. The thickness of the unstretched film can be adjusted by adjusting the slit width of the die, the discharge amount of the polymer, and the rotation speed of the cast drum.Also, the rotation speed of the heating roll group can be adjusted and the tenter can be set. By changing the width, it is possible to stretch at a desired stretching ratio.

When producing a polyester film, the intrinsic viscosity of the polymer is usually preferably 0.6 or more, more preferably 0.65 or more. If the intrinsic viscosity is lower than 0.6, the film-forming stability may be reduced, and it may be difficult to cast a thin product.

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, 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 10 μm, more preferably 0.1 to 5.0 μm, particularly preferably 0.1 to 5.0 μm.
It is 3.0 μm. If the thickness exceeds 10 μm, the piercing property may decrease, and if it is less than 0.1 μm, the film forming stability may deteriorate.

The thermoplastic resin film in the present invention is
The crystal melting energy (ΔHu ₁ ) is preferably 3 to 11
cal / g, more preferably 5-10 cal / g. When ΔHu ₁ is less than 3 cal / g, the independent perforation property of the perforated portion is deteriorated and the printed image is likely to be a blurred image. On the contrary, when ΔHu ₁ exceeds 11 cal / g, the perforation sensitivity is lowered.

As the thermoplastic resin fibers in the present invention, conventionally known ones such as polyester, polyamide, polyphenylene sulfide, polyacrylonitrile, polypropylene, polyethylene or copolymers thereof can be used. From the viewpoint, polyester is particularly preferably used. Preferable examples of the polyester include polyethylene terephthalate, polyethylene naphthalate, polycyclohexane dimethylene terephthalate, and a copolymer of ethylene terephthalate and ethylene terephthalate. From the viewpoint of thermal dimensional stability during perforation, polyethylene terephthalate and polyethylene naphthalate are particularly preferable. These polymers may include flame retardants, heat stabilizers, antioxidants, ultraviolet absorbers, antistatic agents, pigments, if necessary.
Organic lubricants such as dyes, fatty acid esters and waxes, defoaming agents such as polysiloxanes and the like can be added.

The porous support made of thermoplastic resin fibers according to the present invention has an area fraction of the openings formed by the support of 5 to 80% when the support is observed two-dimensionally.
It is preferably 10 to 50%. If the open area fraction is less than 5%, the ink permeability is poor, and the printed image becomes faint and the sharpness deteriorates. If it exceeds 80%, the ink retention will be reduced, and the printed image will be blurred, and
It is easy to show through.

The term "aperture area ratio" as used in the present invention refers to the area occupied by the apertures as a percentage when a certain area of the support is observed in a plane.

In the porous support made of thermoplastic resin fibers of the present invention, the average diameter of the openings formed by the support is 5 to 100 μm, preferably 10 to 60 μm, more preferably 10 to 30 μm. . Average diameter is 5 μm
If it is less than the range, the ink permeability is poor, and the printed image is faint and the sharpness is reduced. When it exceeds 100 μm, the ink holding property is deteriorated, so that the printed image tends to bleed or show-through tends to occur. The average diameter referred to in the present invention is an equivalent circular diameter when the open hole portion is regarded as a circle.

The porous support according to the present invention is preferably formed by forming a mesh-like body in which fibers are irregularly fused to each other at their entanglement points, and has a thin film-like shape at the fiber entanglement points of the fused portion. Formed by folds. That is, the fibers of the support can be formed into a mesh-like body having a fused portion formed by forming a thin film fold, so that the strength of the support can be stabilized and a uniform opening shape can be formed. It is possible to obtain a base paper having a good balance between printing ink retention and transparency. In the present invention, the number of fusion points formed by forming such folds is usually preferably 10 or more per 1 mm ² , and more preferably 1 on the average surface of the support.
It is desirable that there be 00 or more. When the number of fusion points formed by forming the folds is less than 10, not only the strength as a support is insufficient, but also the shape of the openings in the support becomes non-uniform, the ink holding property is deteriorated, and a printed image is obtained. Show-through easily occurs.

The fiber basis weight of the porous support in the present invention is usually preferably ² to ²⁰ g / m ² , and more preferably 5 to 15 g / m ² . Fiber weight is 20g /
If it exceeds m ² , the ink permeability is lowered and the image clarity is lowered. If the fiber areal weight is less than 2 g / m ² , sufficient strength as a support cannot be obtained.

The diameter of the thermoplastic resin fiber constituting the porous support is usually preferably 1 to 60 μm, more preferably 3 to 30 μm, and particularly preferably 5 to 20 μm.
m. If the diameter is smaller than 1 μm, the strength as a support is insufficient and the heat resistance is poor. When the diameter is larger than 60 μm, the thickness of the support and the fiber areal weight are likely to be non-uniform, and the ink transmission is likely to be non-uniform.

The thermoplastic resin fibers forming the porous support of the present invention are preferably stretched and oriented. Generally, the birefringence (Δn) is preferably 0.1 or more, more preferably 0.14 or more. When the birefringence is less than 0.1, the fiber strength is low and the support strength is insufficient.

The crystallinity of the fibers constituting the porous support of the present invention is usually preferably 35% or more, more preferably 40% or more. When the crystallinity is lower than 35%, the heat resistance of the support is insufficient.

The porous support made of thermoplastic resin fibers in the present invention may be papermaking paper made from short fibers, non-woven fabric or woven fabric, screen gauze, etc. A nonwoven fabric is more preferably used in terms of cost.

The non-woven fabric can be produced by a conventionally known direct melt spinning method such as a flash spinning method, a melt blow spinning method, and a spunbond spinning method. For example, in the melt blow spinning method, when the molten polymer is discharged from the spinneret, hot air is blown from the periphery of the spinneret, the discharged polymer is made finer in fineness, and then sprayed on a net conveyor arranged at an appropriate position. It is manufactured by collecting and collecting a web to form a web. By appropriately adjusting the polymer discharge amount, hot air temperature, hot air flow rate, conveyor moving speed, etc., the basis weight of the web and the single yarn fineness can be arbitrarily set.

Similarly, in the spunbond method, the polymer discharged from the die is pulled by an air ejector, and the obtained filament is collided with a collision plate to open the fiber,
It is manufactured by collecting it on a conveyor to form a web. By appropriately setting the polymer discharge amount and the conveyor speed, it is possible to arbitrarily set the fiber basis weight of the web.

In the porous support of the present invention, the surface of the fiber constituting the ink is subjected to chemical treatment with acid, alkali or the like, corona treatment, low-temperature plasma treatment, etc., as necessary in order to impart affinity with the ink. Good.

The base paper in the present invention is made by laminating and integrating the above thermoplastic resin film and a porous support made of thermoplastic resin fibers. The lamination may be performed by using an adhesive under conditions that do not reduce the perforation sensitivity of the film, or the film and the support may be heat-sealed without using the adhesive. From the viewpoint of print clarity and manufacturing cost, it is preferable to perform heat fusion without using an adhesive.

The heat fusion is usually carried out by thermocompression bonding in which the thermoplastic resin film and the porous support are directly attached while heating. The method of thermocompression bonding is not particularly limited, but thermocompression bonding with a heating roll is particularly preferable from the viewpoint of processability.

The thermocompression bonding is preferably carried out after the thermoplastic resin film has been formed and before the stretching step. That is, it is more preferable that a porous support made of the same unstretched thermoplastic resin fiber is laminated on the unstretched thermoplastic resin film and thermocompression bonding is performed. Thermocompression bonding temperature is the glass transition temperature (Tg) and cold crystallization temperature (Tc) of the thermoplastic film.
C) is preferred, and Tg + 10 ° C. to Tg + 50 ° C. is particularly preferred.

In the present invention, it is particularly preferable that the thermoplastic resin film and the porous support are co-stretched in a thermocompression bonded state. By co-stretching in a thermocompression-bonded state, the film and the support can be suitably stretched without being separated as one body. At this time, since the fibers of the support are stretched in a state in which they are irregularly fused to each other at the entanglement points, a mesh suitable for the support can be formed,
In addition, a thin film fold is formed at the fused portion. Also,
By co-stretching the both together, the fibers act as a reinforcing body, so even if the film thickness is thin, it does not break, and it has excellent film-forming stability, and as a result, it is a low-cost base paper. Can be obtained.

The method of co-stretching is not particularly limited, but biaxial stretching is preferred from the viewpoint of improving the perforation sensitivity of the film and the uniform dispersibility of the fibers forming the porous support. The biaxial stretching may be either sequential biaxial stretching or simultaneous biaxial stretching. In the case of sequential biaxial stretching, it is general to stretch in the longitudinal direction and then in the transverse direction, but the stretching may be reversed. The stretching temperature is preferably between the glass transition temperature (Tg) and the cold crystallization temperature (Tcc) of the thermoplastic film. The stretching ratio is not particularly limited, and is appropriately determined depending on the type of thermoplastic polymer used, the sensitivity required for the base paper, and the like, but normally about 2 to 5 times in each of the length and width. Further, after biaxial stretching, it may be re-stretched longitudinally or laterally or longitudinally and laterally.

Further, it is preferable to heat-treat the base paper of the present invention after biaxial stretching. By heat treatment, the perforation sensitivity of the film can be improved, and heat resistance can be imparted to the support. The heat treatment temperature is not particularly limited and may be appropriately determined depending on the type of the thermoplastic polymer used, but is usually 100 to 240 ° C., and the time is preferably 0.5 to 60 seconds.

The crystallinity of the unstretched thermoplastic resin fiber used in the present invention is usually preferably 20% or less, more preferably 15% or less, particularly preferably 10% or less. When the crystallinity exceeds 20%, the fusion between the fibers becomes insufficient, and it is difficult to form a good net-like body during stretching. Further, fusion with the film may be insufficient. Further, it is desirable that the degree of orientation of the unstretched polyester fiber is low,
Usually, the birefringence (Δn) is preferably 0.03 or less, more preferably 0.01 or less. Birefringence is 0.0
When it exceeds 3, co-stretching with the unstretched resin film becomes difficult.

The intrinsic melting point (Tm ₁ ) of the thermoplastic resin film constituting the base paper of the present invention and the intrinsic melting point (Tm ₂ ) of the thermoplastic resin fiber forming the porous support are Tm ₁
It is important that <Tm ₂ and the temperature difference is 20 ° C. or more. If the temperature difference is less than 20 ° C, the heat resistance of the support becomes insufficient.

The peel strength between the thermoplastic resin film constituting the base paper of the present invention and the porous support is preferably 1 g / 2.
It is 5 mm or more, more preferably 5 g / 25 mm or more, and particularly preferably 10 g / 25 mm or more. Peel strength is 1
If it is smaller than g / 25 mm, wrinkles may occur in the base paper when the base paper is fed and conveyed to the printing machine, or in some cases tears may occur.

A release agent is preferably applied to the film surface of the base paper of the present invention to prevent sticking during punching. As the release agent, conventionally known release agents such as silicone oil, silicone-based resin, fluorine-based resin, and surfactant can be used, but the following release agents are particularly preferable.

That is, a release agent containing a mixture of a petroleum wax (A), a vegetable wax (B) and an oily substance (C) which is soluble, emulsified or suspended in water as a main component is particularly preferable. Here, the main component means that the weight ratio of the mixture of (A), (B) and (C) is preferably 50% or more, more preferably 60% or more.

Examples of petroleum waxes include paraffin wax, microcrystalline wax, and oxidized wax. Of these, the use of oxidized wax is particularly preferable.

Examples of the vegetable wax include candela wax, carnaupa wax, wood wax, oliqury wax, sugar cane wax and the like. In the present invention, a composition comprising the following compounds is particularly preferable.

That is, {rosin or disproportionated rosin,
Or hydrogenated rosin / α / β-substituted ethylene (α-substituent: carboxyl, β-substituent: hydrogen, methyl or carboxyl) additive} / alkyl or alkenyl (each having 1 carbon atom)
~ 8) It is particularly preferred to use ester additives of poly (repeating units: 1-6) alcohol.

The mixing ratio of the petroleum wax and the vegetable wax is preferably 10/90 to 90/10% by weight, more preferably 20/80 to 80/20% by weight, and further preferably 30/70 to 70/30. % By weight. The reason why the vegetable wax is 10% by weight or more is that it has good uniform dispersibility when emulsified or suspended in water and is suitable for obtaining a uniform coating film. Further, when the amount of the petroleum wax is 10% by weight or more, the coating film has good slipperiness and good running property at high speed perforation.

In the present invention, a mixture of the above petroleum wax (A) and vegetable wax (B) to which an oily substance is further added is used. Here, the oily substance is a liquid or paste at room temperature. Oil, vegetable oil,
Examples thereof include fats and oils, mineral oils, synthetic lubricating oils and the like. As vegetable oil, linseed oil, kaya oil, saffron oil, soybean oil,
Examples include cinnamon oil, sesame oil, corn oil, rapeseed oil, bran oil, cottonseed oil, olive oil, southern oil, camellia oil, castor oil, peanut oil, balm oil, and coconut oil. Fats and oils include beef tallow, pork oil, sheep oil, cacao oil and the like, and mineral oils include machine oil, insulating oil, turbine oil, motor oil, gear oil, cutting oil, liquid paraffin and the like.
As the synthetic lubricating oil, those satisfying the requirements described in Encyclopedia of Chemistry (Kyoritsu Publishing Co., Ltd.) can be arbitrarily used, and examples thereof include olefin polymerized oil, diester oil, polyalkylene glycol oil, and silicone oil. it can. Among these, mineral oil and synthetic lubricating oil are preferable. Also,
A mixed system of these may be used.

The oily substance (C) is preferably added in an amount of 1 to 100 parts by weight, more preferably 3 to 50 parts by weight, based on 100 parts by weight of the mixture of the petroleum wax (A) and the vegetable wax (B). . If the amount of the oily substance is less than 1 part by weight, the runnability in the high applied energy region is deteriorated. On the other hand, when it exceeds 100 parts by weight, the running property in the low applied energy region is deteriorated.

When any one of the vegetable wax, the petroleum wax and the oily substance is used alone, there is a problem that a uniform coating film cannot be obtained, running property is deteriorated and sticking occurs. Occurs.

Various additives may be used in combination in the above composition within a range that does not impair the effects of the present invention. Examples thereof include antistatic agents, heat-resistant agents, antioxidants, organic particles, inorganic particles and pigments.

Various additives such as dispersion aids, surfactants, preservatives and defoamers may be added to the coating composition for the purpose of improving dispersibility in water.

The thickness of the release agent layer is 0.005 μm or more and is 0.1.
It is preferably 4 μm or less, and more preferably 0.01 μm or more and 0.4 μm or less. Thickness of release agent layer is 0.4μm
If it exceeds, the runnability at the time of punching and the contamination of the head are remarkable.

When the release agent layer is applied in the present invention, the coating liquid is preferably a coating liquid dissolved, emulsified or suspended in water from the viewpoint of explosion proof and environmental pollution.

The release agent may be applied at any stage before or after the film is stretched, or at any stage after the longitudinal stretching and before the lateral stretching, but it is particularly preferable in terms of process to apply the releasing agent before the lateral 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.

If necessary, the coating surface may be subjected to corona discharge treatment in air or other various atmospheres before the release agent is applied.

[0056]

[Characteristics measurement method]

(1) Melting point (° C) Differential scanning calorimeter RDC220 manufactured by Seiko Instruments Inc.
Using the mold, collect 5 mg of sample and raise the temperature from room temperature to 20
It was determined from the peak temperature of the endothermic curve when the temperature was raised at ° C / min.

(2) Crystal melting energy (ΔHu) Differential scanning calorimeter RDC220 manufactured by Seiko Instruments Inc.
Using the mold, it is determined from the area of the film or fiber when it is melted. This area is the area from the baseline to the absorption side by increasing the temperature, and the area until returning to the position of the baseline when the temperature is further increased. Find (a).
In (indium) is measured under the same DSC conditions, and the area (b) is set to 6.8 cal / g, and is calculated by the following equation.

ΔHu = 6.8 × a / b (cal / g)

(3) Fiber diameter (μm) Magnification 2000 at 10 arbitrary points of the sample with an electron microscope
Take 10 times the number of photographs, measure the diameter of any 15 fibers per photograph, do this for 10 photographs, measure the diameter of 150 fibers in total, and use the average value. expressed.

(4) Fiber areal weight (g / m ² ) A 20 cm × 20 cm test piece was taken, and its weight was measured and converted into weight per m ² .

(5) Intrinsic viscosity [η] After drying the sample at 105 ° C. for 20 minutes, 6.8 ± 0.00
5 g was weighed and 160 ° C x 1 in o-chlorophenol
It was dissolved by stirring for 5 minutes. After cooling, the viscosity at 25 ° C. was measured with a Yamatrabotic AVM-10S type automatic viscosity meter.

(6) Crystallinity (%) The sample was placed in a density gradient tube made of a mixed solution of n-heptane and carbon tetrachloride, and the value was read after 10 hours or more to determine the density. The density of crystallinity 0% is 1.335 g / c
m ³ , density of 100% crystallinity 1.455 g / cm ³
As, the crystallinity of the sample was calculated.

(7) Birefringence (Δn) Using a sodium microscope as a light source, a sample was immersed in α-promnaphthalene and the retardation was calculated from the Berek convensor method by a polarizing microscope.

(8) Formation and number of folds at fiber fusion points Samples were made by Topcon Scanning Electron Microscope DS130
Was observed at a magnification of 300 times and the number of fusion points was counted.

(9) Percentage of open area of support (%) The support surface of the base paper was directly observed by the bright-field transmission method of an optical microscope, and was monitored using an image analyzer compatible with Hi-Vision manufactured by Pierce Co., Ltd. The aperture area fraction was determined at a magnification of 240 times. The open area fraction was calculated at 10 arbitrary measurement points and expressed as an average value.

(10) Equivalent circular mean diameter (μm) of the aperture of the support The support surface of the base paper was directly observed by the bright-field transmission method of an optical microscope, and a Hi-vision compatible image analyzer manufactured by Pierce Co., Ltd. was used. Then, a black and white reversal process was carried out at a monitor magnification of 240 times to obtain an equivalent circular diameter of the opening, and the arithmetic mean was calculated. The average value of 10 measurement points was calculated.

(11) Peel strength (g / 25 mm) The peel strength was measured by the 180-degree peel test method according to JIS-K-6854.

(12) Evaluation of printability and show-through property The prepared base paper was supplied to "Lisograph" manufactured by Riso Kagaku Kogyo Co., Ltd., and a character size of 2 mm in JIS 1st level characters by a thermal head type plate making method. 2 with square and 5mm square and ● (circle filled in black)
Plates of 10 mmφ and ruled lines having different thicknesses were prepared as originals. What was printed using a plate-making original was evaluated by visual judgment as follows.

Clarity of Characters Characters that looked similar to the base paper were marked with ◯, lines that were partially cut or stuck differently from the base paper but were readable were marked with Δ, and those that were hardly readable were marked with x.

Thickness Unevenness of Ruled Lines: There was no thickness unevenness at all, Δ was slightly uneven thickness, and x was clearly uneven thickness compared to the original.

White spots in solid black portion: A clear one without any unevenness of light and shade was evaluated as Δ, a slight decrease in density was evaluated as Δ, and a clear white defect was evaluated as x.

Show-through property: Those that did not show-through were marked with ◯, and those that show-through were marked with x.

[0073]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited thereto.

Example 1 Using a rectangular die having a hole diameter of 0.25 mm and 1000 holes, a polyethylene terephthalate raw material ([η] = 0.65, Tm = 257 ° C.) was spun at a die temperature of 290 ° C., and an air ejector was used. At a spinning speed of 2000 m / min, the unstretched nonwoven fabric having a fiber basis weight of 50 g / m ² was dispersed and collected on a conveyer. The nonwoven fabric had a crystallinity of 8% and a birefringence (Δn) of 0.009.

Then, polyethylene terephthalate 82
Copolyester resin raw material ([η] = 0.68, T
m = 212 ° C) is extruded at a T-die die temperature of 280 ° C using an extruder with a screw diameter of 40 mm, and the diameter is 300 mm.
An unstretched film was produced by casting on a cooling drum of

On the unstretched film, the above-mentioned unstretched nonwoven fabric was superposed, supplied to a heating roll and thermocompression bonded at a roll temperature of 90 ° C. to prepare a laminated sheet.

The laminated sheet was stretched 3 times in the length direction with a heating roll at 95 ° C., and then fed into a tenter type stretching machine,
It was stretched 3 times in the width direction at 95 ° C. Further, it was heat-treated at 160 ° C. for 5 seconds inside the tenter to prepare a heat-sensitive stencil sheet. In addition, at the inlet of the tenter, a wax-based release agent was applied to the film surface by a gravure coater with a dry weight of 0.1 g / m ² .

The fiber basis weight of the obtained base paper was 6 g / m ² ,
Opening area fraction is 70.1%, average opening diameter is 62.4μ
It was m. The thickness of the film was 2 μm.

When the base paper was observed with an optical microscope, the fibers of the support formed an irregularly fused network at the entanglement points, and a thin film fold was formed at the fused portion.

Examples 2 to 5 Using a rectangular die having a hole diameter of 0.35 mm and 100 holes,
A polyethylene terephthalate raw material ([η] = 0.6, Tm = 254 ° C.) was spun by a melt blow method at a die temperature of 280 ° C., fibers were dispersed and collected on a conveyor, and a fiber areal weight was 40, 60, 80, 100 g. / M ² of unstretched non-woven fabric was prepared. The non-woven fabric had a crystallinity of 7% and a birefringence (Δn) of 0.008.

Then, polyethylene terephthalate 82
Copolyester resin raw material ([η] = 0.68, T
m = 212 ° C) is extruded at a T-die die temperature of 280 ° C using an extruder with a screw diameter of 40 mm, and the diameter is 300 mm.
An unstretched film was produced by casting on a cooling drum of

On the unstretched film, the above-mentioned unstretched nonwoven fabric having a fiber basis weight of 40 g / m ² was superposed, supplied to a heating roll and thermocompression bonded at a roll temperature of 80 ° C. to prepare a laminated sheet.

The laminated sheet was placed between heating rolls at 90 ° C.,
After stretching 3 times in the length direction, it was fed into a tenter type stretching machine, stretched 4 times in the width direction at 95 ° C., and further heat-treated at 160 ° C. for 5 seconds inside the tenter. The heat release stencil sheet of Example 2 was prepared by applying a wax-based release agent at the inlet of the tenter to the film surface with a gravure coater at a dry weight of 0.1 g / m ² .

The fiber basis weight of the obtained base paper was 3.8 g / m.
² , the open area fraction is 53.9%, the open average diameter is 18.
It was 5 μm. The thickness of the film was 2 μm.

When the base paper was observed with an optical microscope, the fibers of the support formed an irregularly fused network at the entanglement points, and a thin film fold was formed at the fused portion.

Similarly, an unstretched non-woven fabric having a fiber basis weight of 60 g / m ² was used to prepare a heat sensitive stencil base paper of Example 3.
The fiber basis weight of the base paper was 5.4 g / m ² , the opening area fraction was 42.5%, and the average opening diameter was 15.5 μm. The thickness of the film was 2 μm.

When the base paper was observed with an optical microscope, the fibers of the support formed an irregularly fused network at the entanglement points, and a thin film fold was formed at the fused portion.

Similarly, the fiber areal weight is 80 g / m ² and 10
Examples 4 and 5 using 0 g / m ² of unstretched nonwoven fabric
A heat-sensitive stencil sheet was prepared. The fiber basis weight of the base paper of Example 4 was 7.5 g / m ² , the open area fraction was 29.2%, and the open average diameter was 10.6 μm. The fiber basis weight of the base paper of Example 5 was 9 g / m ² , and the open area fraction was 15.
3% and the average pore diameter was 8.0 μm. Both films had a thickness of 2 μm.

When these base papers were observed with an optical microscope, the fibers of the support formed a mesh-like body which was irregularly fused at the entanglement points, and a thin film fold was formed at the fused portion.

Example 6 An unstretched nonwoven fabric having a fiber basis weight of 100 g / m ² prepared in Example 2 was prepared.

Then, an unstretched film was prepared using the same raw material as in Example 2, and the film and the unstretched nonwoven fabric were thermocompression bonded, and the stretching ratio in the length direction was 3 times and the stretching ratio in the width direction was 3 times. A stencil sheet for heat-sensitive stencil was prepared under the same conditions as in Example 2 except that the number was doubled.

The basis weight of the base paper was 11 g / m ² , the open area fraction was 7.2%, and the open average diameter was 6.8 μm. In addition, when the base paper was observed with an optical microscope, the fibers of the support formed a reticulated body that was irregularly fused at the entanglement points,
In addition, a thin film fold was formed on the fused portion.

Comparative Example 1 Using a rectangular die having a hole diameter of 0.25 mm and 500 holes,
A polyethylene terephthalate raw material ([η] = 0.65, Tm = 254 ° C.) was melted at a discharge rate of 300 g / min.
Spin at 0 ° C, spin speed 500 with air ejector
The fiber was pulled at 0 m / min to disperse and collect the fibers on the conveyor to prepare a nonwoven fabric having a fiber basis weight of 8 g / m ² .

Next, a copolymerized polyester resin consisting of 82 mol% polyethylene terephthalate and 18 mol% polyethylene isophthalate was biaxially stretched to prepare a polyester film having a thickness of 2 μm.

Next, the porous support and the polyester film were bonded together using an adhesive (vinyl acetate resin). The amount of adhesive applied was 1 g / m ² . Next, a wax-based release agent was applied to the film surface at a dry weight of 0.1 g / m ² to prepare a heat-sensitive stencil sheet.

The open area ratio of the base paper was 82.4%, and the open average diameter was 110.5 μm.

Comparative Example ² The non-woven fabric having a fiber basis weight of 8 g / m ² prepared in Comparative Example 1 was
Laminate the sheets, thermocompression-bond with an embossing roll at 220 ° C,
A porous support having a thickness of 80 μm was prepared.

Next, the polyester film having a thickness of 2 μm prepared in Comparative Example 1 was attached with an adhesive (vinyl acetate resin). The amount of adhesive applied was 1 g / m ² . Next, the weight of the wax release agent on the film surface after drying was 0.1 g /
m ^{2 was} applied to prepare a heat sensitive stencil base paper.

When the base paper was observed with an optical microscope, it was observed that the fibers of the support were regularly fused at the embossing points. The opening area fraction of the base paper was 4.6% and the opening average diameter was 4.3 μm.

[0100]

[Table 1] As can be seen from the results in Table 1, the heat-sensitive stencil sheet of the present invention having a support having an open area ratio of 5 to 80% and an open hole average diameter of 5 to 100 µm has good printability and a back surface. There is no reflection.

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Claims (5)

[Claims] 1. A heat-sensitive stencil sheet comprising a thermoplastic resin film and a porous support made of thermoplastic resin fibers laminated on the thermoplastic resin film, wherein the porous support has an open area ratio of 5 to 80.
% And an average aperture diameter of 5 to 100 μm, a heat-sensitive stencil sheet. 2. The porous support fibers are irregularly fused to each other at their entanglement points to form a net-like body, and a thin film fold is formed at the fused portion. The heat-sensitive stencil base paper according to claim 1. 3. The heat-sensitive stencil sheet according to claim 1, wherein the thermoplastic resin film and the thermoplastic resin fibers are made of a polyester resin. 4. A method for producing a heat-sensitive stencil sheet, which comprises subjecting an unstretched thermoplastic resin film and a porous support made of unstretched thermoplastic resin fiber to thermocompression bonding and then biaxially co-stretching. 5. The method for producing a heat-sensitive stencil sheet according to claim 4, wherein the unstretched thermoplastic resin film and the unstretched thermoplastic resin fiber are made of a polyester resin.