JPH09290580A - Luffa-like porous body and original printing plate for heat-sensitive stencil used thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize the uniformized flow of liquid such as ink or the like without drifting at printing and the transmission without causing clogging irrespective of the change of the heat energy given by a thermal hear by a method wherein a luffa-like porous body made of a synthetic resin is employed. SOLUTION: A mixture, which is prepared by dissolving a polyvinyl acetal resin composition in a solvent and after that, adding the solvent, which is not dissolving the composition, and fully mixing with each other, is applied into the surface of a thermoplastic resin film used as an original printing plate for heat-sensitive stencil. As a result, since the added solvent has no solubility to the composition, the resultant solution becomes gelled. By a drying treatment, the solution is evaporated, resulting in forming a luffa-like porous film on the surface of a thermoplastic resin film and, after being dried, a porous film is obtained. By adheringly providing the luffa-like porous body made of the above- mentioned synthetic resin on one side of the thermoplastic resin film, favorable boring can be realized even under the change of the heat energy of a thermal head.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a fibrous porous body having a specific shape and a heat-sensitive stencil printing plate precursor using the porous body.

[0002]

2. Description of the Related Art A heat-sensitive stencil printing plate comprises an ink-permeable porous support and a thermoplastic resin film which is perforated by heating. The thermoplastic resin film is
The smaller the thickness, the higher the sensitivity and the quality of the image when drilling.
However, although it has been considered difficult to reduce the thickness to about 1 μm due to the manufacturing problem of thinning, due to the progress of thin film manufacturing technology,
This problem has been overcome (JP-A-60-6719).
6, JP-A-62-176296). Further, the physical properties of the thermoplastic resin film are also amorphous (JP-A-62-2).
82983), those having a melting point of 200 to 250 ° C. and a glass transition temperature of 70 ° C. or higher (JP-A-2-307788). From the above, it has become possible to obtain a thermoplastic resin film capable of excellent perforation. As such excellent thermoplastic resin film appeared,
In the plate making of heat sensitive stencil printing, it is required to transfer the heat energy to the thermoplastic resin film as evenly as possible, the porous support maintains the heat insulation condition as much as possible, and even if the thermal energy of the thermal head fluctuates, the thermoplastic resin There is an increasing demand for good perforation of films. As a solution to this problem, it has been proposed to arrange the fibers in one direction in a support made of natural fibers or synthetic fibers (Japanese Patent Publication No. 2-5264).
0). However, with this support, a phenomenon occurs in which the ink is agglomerated between the fibers, and the ink cannot pass through, so that there is a problem in that the obtained printed image has white spots. In addition, a heat-sensitive stencil printing plate precursor was devised in which a support was formed on one side of a thermoplastic resin film, which was made to allow the ink to pass through as a mixed solution of water-dispersible polymer and colloidal silica in the form of fine particles. (JP-A-4-7198). However, in this case, it is necessary to use an adhesive for bonding the support and the thermoplastic resin film, and the perforation sensitivity decreases due to the influence of the adhesive,
The image density for printing is not sufficient, and the roughness of silica on the surface of the support is as small as 0.06 μm to 10 μm, so the heat insulating effect at the time of perforation is not sufficient, and the ink has low viscosity. It has been pointed out that there are problems such as having to choose only one.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to have a heat insulating effect regardless of the fluctuation of thermal energy provided by a thermal head, and at the time of printing, an average amount of liquid such as ink does not drift in a constant amount. It flows into a stream and can penetrate without causing clogging,
It is an object of the present invention to provide a porous body capable of adhering to a thermoplastic resin film without using an adhesive for the thermoplastic resin film, and a heat-sensitive stencil printing original plate using the porous body.

[0004]

The present inventors have completed the present invention as a result of intensive research to solve the above problems. That is, the present invention provides a fibrous fibrous porous body made of a synthetic resin and a heat-sensitive stencil printing original plate using the porous body.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The characteristic feature of the shape of the fibrous fibrous porous material of the present invention is that the fibers found in the dried fibrous gourd are entangled. This porous structure does not form a fibrous shape by intersecting vertical and horizontal fibers such as natural fibers and synthetic fibers, but it has a three-dimensional spread due to branched fibers, and voids are formed inside it. The shape of the voids is a melon-like shape, not a perfect spherical shape (FIGS. 1 to 3). The size and the open pore ratio of the fibrous fibrous porous voids can be appropriately adjusted depending on the production method. The open pore ratio is generally 10% to 85%, and the thickness of the fiber is 2 μm to 10 μm. Then, the openings are present in a thickness of 10 to 50 μm with respect to the plane. The fibrous fibrous porous body of the present invention can be used as a separation membrane that allows a gas or a liquid to pass therethrough. It has excellent water repellency as its characteristics, has extremely high elasticity, has a milky white color, has a clean feeling, and has a surface that reflects light appropriately, so it can be used as an interior for curtains and the like. By providing a layer of this porous body on one surface of the thermoplastic resin film, it can be used as a printing original plate for heat-sensitive stencil. When used as a printing original plate for heat-sensitive stencil, the size of porous voids is an important factor. When observing the porous voids in a planar shape, the pore diameters are distributed in the range of 1 μm to 50 μm in terms of a true circle. If the pore size is less than 1 μm, the heat insulating effect of the porous body is suppressed, so that the perforation sensitivity of the thermoplastic film is significantly impaired, and the ink permeability is also reduced, which is not preferable. In this case, since the ink permeability is not sufficient,
When a low-viscosity ink is used, a bleeding may occur in the printed image, or the ink may be miserable from the side of the printing drum or the rear end of the stencil sheet that is wound. This pore size is 5
If the thickness is 0 μm or more, the ink will pass through too easily, and excessive ink will adhere to the printing spot, show-through will occur, and problems such as blurring will occur in the printed image.

The fibrous fibrous porous body is produced by subjecting a synthetic resin composition having a particular component composition to a particular treatment. The synthetic resin having a specific component composition which is the source of the fibrous fibrous porosity is composed of a specific proportion of polyvinyl acetal, polyvinyl alcohol and a copolymer of vinyl acetate, and the polymer end group is composed of polyvinyl acetal, polyvinyl alcohol and vinyl acetate. It has a structure. The overall structural formula is as follows.

Embedded image (In the formula, R is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms,
X is a number from 70 to 85, Y is a number from 10 to 25, and Z is 0.5.
It is a number of -10. ) A polyvinyl acetal, polyvinyl alcohol and vinyl acetate composition having a specific ratio can be represented by X, Y, Z (Wt%) representing the amount of each composition shown in the above structural formula. X is 70 to 85, preferably 75 to 8
3, Y is 10 to 25, preferably 11 to 22, and Z is a value in the range of 0.5 to 10, preferably 0.5 to 7. And, it is effective when the ratio of X to Y is in a specific range. When the ratio of X to Y is 7: 1, it can be dissolved in the solvent used, and when it is 5: 1 to 4: 1, it can be further dissolved in the solvent. A resin having a composition of X, Y, and Z in these specific proportions has a softening point of 70 ° C. to 85 ° C., which gives good results, and a glass transition point of 50 ° C. to 9 ° C.
The range of 0 ° C. gives good results. Further, the molecular weight (weight average) affects the size of the fiber pores of the melon-like porous membrane. If the composition ratio of polyvinyl acetal, polyvinyl alcohol and vinyl acetate is constant, it depends on the molecular weight, and as the molecular weight increases, the interfiber pores become smaller. For the above reasons, the molecular weight is selected from the range of 30,000 to 320,000. If the molecular weight is less than 30,000, the pore size becomes too large, which is not suitable. When the molecular weight exceeds 320,000, it becomes insoluble. The specific composition is shown in Table 1.

[0007]

[Table 1] (Note) The substituent R of the polyvinyl acetal copolymer in Table 1 is C ₃ H ₇ .

The specific treatment for a specific resin is as follows. A composition (hereinafter referred to as a polyvinyl acetal resin composition) composed of the above-mentioned specific proportions of polyvinyl acetal, polyvinyl alcohol and vinyl acetate is dissolved in a solvent. Next, a solvent that does not dissolve the polyvinyl acetal resin composition is added to a solution containing the polyvinyl acetal resin composition, mixed well, and applied on the surface of a thermoplastic resin film used for a printing original plate for heat-sensitive stencil printing.
Since the solvent added to this polyvinyl acetal resin is not soluble in the polyvinyl acetal resin composition, the solution in which the polyvinyl acetal resin composition is dissolved has a gel form. When the gel-like polyvinyl acetal resin solution applied on the surface of the thermoplastic resin film is dried, the solution evaporates, and the desired spruce fibrous porous film is formed on the surface of the thermoplastic resin film.

Next, this step will be described in more detail. The solvent that first dissolves the polyacetal resin composition is one that can uniformly dissolve polyvinyl acetal, and it can be evaporated when the thermoplastic resin film is applied and dried. As these solvents, alcohols, ketones, ethers, ketone esters, ketone alcohols, ketone ethers and the like can be used. As alcohols,
Examples thereof include ethyl alcohol, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, i-butyl alcohol, 2-ethylbutyl alcohol, 2-ethylhexyl alcohol, cyclohexanol, methylamyl alcohol and benzyl alcohol. As the ketones, acetone, diethyl ketone,
Examples thereof include dipropyl ketone, diisobutyl ketone, amyl ketone, and acetonylacetone. Examples of ethers include ethyl ether, i-propyl ether, butyl ether, diethyl carbitol, diethyl cellosolve and the like. Examples of ketone esters include ethyl acetoacetate and ethyl pyruvate. Examples of ketone alcohols include i-propyl cellosolve, carbitol bricidol, cellosolve, glycol ether, benzyl cellosolve, butyl carbitol, butyl cellosolve, methyl carbitol, methyl cellosolve, triethylene glycol and monoethyl ether. You can
Examples of ketone ethers include acetal ethyl.

The polyvinyl acetal resin composition is dissolved in these solvents to a concentration of 3 to 30% by weight, preferably 5 to 20% by weight. The solvent that does not dissolve the added polyvinyl acetal resin composition in the solution of the polyvinyl acetal resin composition is water, hydrocarbon, or chlorinated hydrocarbon. Examples of hydrocarbons include n-hexane and cyclohexane. Examples of the chlorinated hydrocarbon include chloroform and carbon tetrachloride. The amount of this solvent added is 10 to 40% by weight. The addition is stopped just before cloudiness occurs. Add 15
It is carried out at a temperature of from 20 to 20 ° C. When this solvent is added, the solution of the polyvinyl acetal resin composition will be in a solubilized state. After sufficiently stirring this solution, it is applied to the surface of the thermoplastic resin film. This thickness is generally 3 μm to 15
μm. The resulting porous film is three times as layered.

The thermoplastic resin film coated with the solution containing the polyvinyl acetal resin solution in the solubilized state is heated and dried with hot air at 50 to 60 ° C. The heating time is 30 to 60 seconds. By drying this, a porous film having a thickness of 10 μm to 50 μm can be obtained. An inorganic pigment, natural fiber, or the like may be added to and dispersed in this liquid in order to enhance the strength of the porous body. The amount of gelled polyvinyl alcohol applied to the thermoplastic resin film to reach the target thickness is grasped in advance through preliminary experiments, etc., and handling is also taken into consideration.
It is effective to apply the resin liquid on the film. The acetal polymer also includes formal and butyral. Further, when high physical strength is required, melamine conversion with methylol urea and urethane conversion or epoxidation with isocyanate are possible.

For the purpose of improving the physical strength of the fibrous fibrous porous material of the present invention, it is possible to use an inorganic pigment, for example, a particle of a clay component or a metal salt. Above all, the addition of silica particles is effective. The silica particles used in the present invention,
By mixing with the porous membrane resin, the effect of increasing the physical strength of the porous membrane can be expected, and at the same time, the effect of suppressing blocking during the production of the porous membrane can be expected. Further, since the silica particles have a large specific surface area, an effect of reducing the content of polybutyral resin which is a main raw material of the porous membrane of the present invention can be expected. The silica particles having a diameter in the range of 1 μm to 30 μm exhibit excellent effects on fluidity and strength of the porous membrane. When it exceeds 30 μm, the pores are enlarged, which hinders the formation of the porous membrane of the present invention. If a submicron particle having a particle size less than this is used, the resin liquid thickens, the fluidity is lost, and processing is hindered. If the particle diameter is in the above range, for example, the viscosity characteristic is 20 c. An effect such as a decrease of about P and an increase of about 5 to 10 mN (Mpa) in bending rigidity, which is one of the physical strengths of the porous film, was obtained. The above-mentioned effects are related to the oil absorption amount of the physical properties of silica, and the oil absorption amount is 190 ml / g-
300 ml / g adsorbs the resin liquid well, and the effect can be expected. If the oil absorption exceeds 300 ml / g, the specific surface area becomes too large, resulting in thickening of the resin liquid,
It loses fluidity and causes trouble. Also, 190 ml / g
If it is less than the above, the amount of the resin liquid adsorbed decreases, and the effect cannot be expected. The amount of silica used may be selected in advance in a preliminary experiment because the viscosity of the resin liquid forming the porous film varies. The porous body of the present invention has a structure in which fibrous fibrous porous material is laminated. From the physical properties of the film, it is excellent in gas permeability and water repellency, has high elasticity, and is used as a porous body alone.

Specific examples of the material constituting the thermoplastic film of the master for stencil printing of the present invention include polyester, nylon, polyolefin, polystyrene, polyvinyl chloride, polyacrylic acid ester, ethylene and vinyl alcohol. Examples thereof include polymers and polycarbonate-based copolymers. Of these, polyester is the most preferable. This polyester is a substantially amorphous polyester film. The acid component of the polyester is selected from phthalic acid, aliphatic dicarboxylic acids, or three types having a substituent on the hydrocarbon group of the dicarboxylic acid. The alcohol component of the polyester is selected from alkylene glycols, saturated aliphatic cyclic glycols, or aromatic diols. Specific examples of the polyester include terephthalic acid or terephthalic acid containing 15 mol% or less of isophthalic acid and / or phthalic acid as an acid component, and a mixed diol containing ethylene glycol and cyclohexanedimethanol as a main component as an alcohol component. It is a film made of condensed polyester. Especially the alcohol component composition is ethylene glycol 60
~ 80 mol%, 1,4-cyclohexanedimethanol 4
The polyester film is 0 to 20 mol%. The thermoplastic resin film is manufactured by using these materials by an extrusion method or a casting method.

The thickness of the thermoplastic resin film is from 1 μm to
It is 15 μm, preferably 1 μm to 4 μm. The thermoplastic resin film has a heat shrinkage stress at 100 ° C. of 75 to 55.
0 g / mm ² preferably 300~550g / mm ^2, the crystallinity is 5% or less of the resin film.

In the printing base paper for heat-sensitive stencil of the present invention,
By providing the heat-sealing prevention layer on the thermoplastic resin film, it is possible to prevent the residue from being fixed to the thermal head by heat-sealing the film or the adhesive. For example, a surfactant silicone-based release agent, a lubricant and the like are suitable for the above-mentioned purpose heat-sealing preventive layer, and more generally, in a roll-wound heat-sensitive stencil printing base paper, the porous layer is used. A material that can maintain the releasing property for a long time without being transferred is preferably used. It is possible to add an antistatic agent to the heat-sealing prevention layer, and the thickness of the heat-sealing prevention layer is 0.1.
The thickness is preferably 01 to 1.0 μm. The present invention, as an ink-permeable substrate that has been conventionally used, Japanese paper, non-woven fabric,
Since thin paper such as Manila hemp is not used, no adhesive is required, and there are problems with respect to perforation sensitivity and thermal curl.

[0016]

EXAMPLES Next, the present invention will be specifically described with reference to examples and comparative examples, but the present invention is not limited to these examples. Example 1 Polyvinyl butyl acetal resin (vinyl acetate component 2% by weight,
21% by weight of Poval component, 77% by weight of polyvinyl butyl acetal component) Resin having an average molecular weight of 30,000 (A in Table 1)
Was dissolved in ethanol to obtain a 20% solid content concentration.
Next, while heating this resin solution to 40 ° C., 5 g of water was added dropwise with stirring. The solution became slightly cloudy when water was added (this was found to be a phenomenon observed in micelle formation of surfactants, etc., and was found to be no problem). This resin solution was applied to a commercially available PET film by selecting a doctor so as to have a thickness of 20 μm. While preventing the mixture of water,
Evaporate the solvent in a drying box at 60 ° C, then
By peeling off from the ET film and winding up, the gourd fibrous porous material of the present invention was obtained. The shape of the fibrous fibrous porous body of Example 1 was observed by an electron microscope (Hitachi, SEM-S).
-2400) is as shown in FIG.

Example 2 A thermoplastic resin film having a crystallinity of 1.0% was used.
The heat shrinkage stress at 0 ° C. is 480 to 500 g / mm ² ,
A resin solution having the following composition (resin A in Table 1) having an adhesion amount of 100 g / m ^{2 was} applied to a 3.5 μm-thick copolyester film exhibiting a melting temperature of 180 ° C. and dried under a drying condition of 50 ° C. for 1 minute. Then, a printing base paper for a porous film heat-sensitive stencil was prepared. Resin solution A> Polyvinyl acetal resin A (prototype manufactured by Sekisui Chemical Co., Ltd.) 20 parts by weight (ratio of polyvinyl acetal, polyvinyl alcohol and vinyl acetate (X, Y, Z) X77% by weight, Y21% by weight, Z2% by weight) , Molecular weight 3 × 10 ⁴ Methyl ethyl ketone 40 parts by weight Toluene 40 parts by weight As a result of observing the porous state of the prepared heat-sensitive stencil printing base paper with a SEM (S-2400) manufactured by Hitachi, Ltd., it was found that fiber pores on the thermoplastic resin film were 30 μm in terms of perfect circles A printing base paper support for heat-sensitive stencil comprising a fibrous porous material was obtained.

Example 3 Using the thermoplastic resin film used in Example 2, a resin solution (resin B in Table 1) having the following composition was stirred in a warm water atmosphere at 40 ° C. for 30 minutes, and after confirming dissolution, adhesion was performed. Amount 85g /
m ² was applied with a doctor and dried under an atmosphere of 60 ° C. for 1 minute to prepare a fibrous fibrous heat-sensitive stencil printing base paper of the present invention. Resin solution B> Polyvinyl acetal resin B (prototype manufactured by Sekisui Chemical Co., Ltd.) 20 parts by weight (proportion of X, Y, Z X79% by weight, Y19% by weight, Z2% by weight), molecular weight 7 × 10 ⁴ Ethanol 60 parts by weight Water 20 parts by weight The prepared printing base paper for heat-sensitive stencil was observed with an electron microscope (SEM-S-2400) manufactured by Hitachi, Ltd. in the same manner as in Example 2. As a result, interfiber pores were formed on the thermoplastic resin film. A heat-sensitive stencil sheet was obtained in which a melon-like fibrous porous material having a true circle equivalent of 15 μm supported a thermoplastic film (FIG. 2).

Example 4 The resin (B) described in Example 2 was replaced with the following resin (resin C in Table 1).
A printing base paper for heat-sensitive stencil was prepared by all the same steps except that the above procedure was changed. Resin solution C> Polyvinyl acetal resin C (prototype manufactured by Sekisui Chemical Co., Ltd.) 18 parts by weight (proportion of X, Y, Z X79% by weight, Y19% by weight, Z2% by weight), molecular weight 9 × 10 ⁴ Methyl ethyl ketone 32 parts by weight Toluene 32 parts by weight FPS-2 (Shionogi Pharmaceutical Co., Ltd.) 18 parts by weight Oil absorption 280 m / 1D 503 μm The back side of the prepared heat-sensitive stencil printing base paper is an electron microscope manufactured by Hitachi (SEM-S-2400). As a result of observation, the inter-fiber pores on the thermoplastic resin film were 10 μm in terms of perfect circles.
The melon-like fibrous porous membrane of was observed (Fig. 3).

Example 5 The resin (B) described in Example 2 was replaced with the following resin (Resin D in Table 1).
All were processed in the same manner as in Example 2 except that the above was replaced with. Resin solution D> Polyvinyl acetal resin D (prototype manufactured by Sekisui Chemical Co., Ltd.) 18 parts by weight (ratio of X, Y and Z: X79% by weight, Y19% by weight, Z2% by weight), molecular weight 7 × 10 ⁴ Methanol 32 parts by weight Toluene 32 parts by weight FPS-24 (Shionogi Seiyaku Co., Ltd.) 18 parts by weight Oil absorption 280 m / l D507 μm The porous body of the prepared heat-sensitive stencil printing base paper was manufactured by Hitachi SEM (S-2400). As a result of the observation, a melon-like fibrous porous body having inter-fiber pores of 5 μm in perfect circle was observed on the thermoplastic resin film.

Comparative Example 1 Commercially available VYHH (Union Carbide) (83% by weight vinyl chloride and 17% by weight vinyl acetate composition) A resin having an average molecular weight of 40,000 was dissolved in acetone to obtain a solid content concentration of 20%. To this, 5 g of ethanol was added dropwise with stirring,
In the same manner as in Example 1, it was dissolved while heating to 40 ° C. As a result, the liquid became cloudy. This resin solution was applied to a commercially available PET film by selecting a doctor so as to have a thickness of 20 μm. Evaporate the solvent in a dry box at about 60 ° C
It was peeled off from the T film. (In this case, mixing of water into the dry atmosphere was prevented as much as possible.) By the above treatment, a porous body was obtained. As in the case of the example, as a result of observation with an electron microscope SEMS-2400 manufactured by Hitachi, Ltd., this shape had bubbles generated on the resin plane.
It was a circular porous body of 0 μm to 50 μm (FIG. 4).

Comparative Example 2 A thermoplastic resin film having a crystallinity of 10% is 100%.
A polyester copolymer film having a heat shrinkage stress at 150 ° C. of 300 to 300 g / mm ² and a melting temperature of 180 ° C. and a thickness of 3.5 μm was used instead of the resin A of Example 2, and
The resin I was treated in the same manner to prepare a heat-sensitive stencil printing base paper. As a result of observing this sample with an electron microscope (SEM-S-2400 manufactured by Hitachi, Ltd.), no fibrous porous film was observed on the thermoplastic resin film.

Comparative Example 3 The resin A of Example 2 was replaced with the resin J of Table 1, and a printing base paper for heat-sensitive stencil was prepared in the same process. As a result of observing this sample with an electron microscope (SEM-S-2400 manufactured by Hitachi, Ltd.), a porous film was formed on the thermoplastic resin film, but the resin was insolubilized on the film.

Comparative Example 4 In the method of preparing the printing base paper for heat-sensitive stencil of Example 2, all were prepared by the same steps except that the following resin solution E was used in place of A. Resin solution E> Vinyl acetate polymer (Daicel chemistry: Sepian A-700) 20 parts by weight Ethanol 40 parts by weight Isopropyl alcohol 20 parts by weight Toluene 20 parts by weight Electron microscope (Hitachi) As a result of observation with SEM-S-2400 manufactured by Seisakusho Co., Ltd., a resin film of a porous body different from the porous film of fibrous fibrous fiber aimed at by the present invention was observed on the thermoplastic resin film.

Comparative Example 5 The same procedure as in Example 1 was repeated except that the following resin solution E was used in place of A, according to the method for preparing the heat-sensitive stencil printing base paper. Resin solution F> Vinyl chloride-vinyl acetate polymer 20 parts by weight (manufactured by Union Carbide: VYHH) Ethanol 40 parts by weight Isopropyl alcohol 20 parts by weight Toluene 20 parts by weight The porous pattern of the prepared base paper for heat-sensitive stencil printing is prepared. As a result of observation with an electron microscope (SEM-S-2400 manufactured by Hitachi, Ltd.), a circular porous resin film was observed on the thermoplastic resin film. It was the same as the figure of Comparative Example 1.

Table 1 shows the results of a test conducted by the following method using the printing stencil sheet for heat-sensitive stencil obtained as described above. (1) Perforation Sensitivity (Substitute Characteristic for White Spot Evaluation) Regarding a predetermined printing base paper for heat-sensitive stencil, the line type thermal head of the plate making part of Preport VT-3500 manufactured by Ricoh Co., Ltd. was used to adjust the applied energy. The optical density of the black evening area (stabilized area produced by printing in standard conditions and character mode) was punched with and the densitometer RD-91 manufactured by Macbeth was used.
The value when the standard black sample was used as a blank is defined as the perforation sensitivity. This value is 1.11 or more as ⊚, 1.00 or more as O, 0.99 to 0.88 as Δ, and 0.88 or less as X. (2) Image distortion rate Using the line-type thermal head of the plate-making section of Preport VT-3500 manufactured by Ricoh Co., Ltd., perforation was performed under the adjusted applied energy, and the initial printed image and 3000 printed images were printed. The shape was evaluated with an optical microscope, and the change rate of the predetermined shape was displayed as a percentage. (3) Bending Stiffness A heat-sensitive stencil printing base paper is made into a predetermined size, and a commercially available bending stiffness meter (manufactured by LORENTZEN & WETTRE) ST
IFFNESS TESTER).

[0027]

[Table 2]

Comparing the evaluation results of the examples with those of the comparative example in Table 2, it is clear that the perforation sensitivity and the image density of the comparative example are clearly inferior to those of the example. Also,
In Examples 2 and 3, the molecular weight was increased and the fiber interstices and the ink were well matched. As a result, it was found that good image density and perforation sensitivity were obtained. There was no white spot and the back stain seen in the comparative example was improved in the example and could not be found. Regarding the bending stiffness characteristics, the effect of the inorganic silica is shown as an increase of 5 mmN in Examples 4 and 5, and in Example 5, the image density, white spots,
It can be seen that the image distortion rate and the bending rigidity are all excellent.

[0029]

EFFECT OF THE INVENTION By providing the fibrous fibrous porous body made of the synthetic resin of the present invention on one surface of the thermoplastic resin film, a heat-sensitive stencil sheet of high sensitivity and low energy can be obtained. By controlling the molecular weight of a polyvinyl acetal resin polymer contained in a synthetic resin, the pore size can also be controlled, the back stain-free, the image density is excellent, and the cost-effective printing base paper is provided.

[Brief description of drawings]

FIG. 1 is a view of observing a fibrous fibrous porous body of the present invention with an electron microscope.

FIG. 2 is a view in which the fibrous fibrous porous body of the present invention is observed by an electron microscope.

FIG. 3 is a view in which the fibrous fibrous porous body of the present invention is observed by an electron microscope.

FIG. 4 is a view of observing a porous body having bubbles on a resin plane of a conventional example.

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[Procedure amendment]

[Submission date] July 29, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Fig. 4

[Correction method] Change

[Correction contents]

FIG. 4 is a view obtained by observing with an electron microscope a porous body in which bubbles are generated on a resin surface of a conventional example.

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Claims (6)

[Claims] 1. A fibrous fibrous porous body made of a synthetic resin. 2. A fibrous fibrous porous body in which the synthetic resin according to claim 1 comprises a polyvinyl acetal resin polymer. 3. A fibrous fibrous porous body according to claim 1 or 2, wherein the porosity of the fibrous fibrous porous body formed as fibrous fibrous has a perfect circle equivalent diameter in the range of 1 μm to 50 μm. Body. 4. A spruce fibrous porous body, wherein the polyvinyl acetal resin polymer according to claim 2 has a molecular weight in the range of 3 × 10 ⁴ to 30 × 10 ⁴ . 5. An oil absorption amount of 190 ml / g to 300 ml / g in the fibrous fibrous porous body according to any one of claims 1 to 5.
A fibrous porous fibrous body characterized by containing the above silica. 6. A printing original plate for a heat-sensitive stencil, comprising a layer of the fibrous fibrous porous material according to claim 1 provided on one surface of a thermoplastic resin film.