JPH0645185B2 - Porous composite sheet and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is excellent in surface smoothness, hydrophilicity, mechanical properties, and the like.
The present invention relates to a porous composite sheet suitable as a water absorption plate, a humidity control plate, a water evaporation plate, etc., and a method for producing the same.

(Conventional technology) Conventionally, polyethylene, polypropylene, polystyrene,
A porous sheet having continuous pores formed by sintering and molding fine particles of a thermoplastic polymer such as polymethylmethacrylate and polyacrylonitrile is known.
These porous sheets are widely used for applications such as air diffusers and filter media.

Since these porous sheets are hydrophobic due to the characteristics of the thermoplastic polymer used as the material, their applications have been limited.

Therefore, the present inventors have proposed a method for producing a porous molded article by sintering and molding fine particles of a thermosetting phenolic resin, which is a phenolic resin having a certain degree of hydrophilicity and has a specific heat fluidity. It was previously proposed (Japanese Patent Laid-Open No. 63-63727). However, the porous sheet obtained by the above method is not sufficient in mechanical properties such as bending strength because the fine particles of the phenol resin are simply sintered and fused by point adhesion. Furthermore, porosity is 40% at best
It was difficult to reduce the weight of the porous body because the degree was limited.

Then, in order to solve such a problem, the present inventors have developed a porous composite sheet excellent in mechanical properties and air permeability from a reinforcing fiber and a specific thermosetting phenol resin, and a manufacturing method thereof. Proposed (Japanese Patent Laid-Open No. 1-165427). However, although the porous composite sheet according to this proposal can retain a certain amount of water, it has a problem that a sufficient water absorption rate cannot be obtained.

(Problems to be Solved by the Invention) In order to solve such a problem, the present inventors have a large porosity first, and have excellent mechanical characteristics such as bending strength and hydrophilicity despite the large porosity. , A porous composite sheet with a particularly high water absorption rate and a method for producing the same have been proposed (Japanese Patent Application No. 63-114).
No. 369). However, although the porous composite sheet according to this proposal has significantly improved the water absorption property, there remains a problem to be improved in the surface smoothness of the sheet.

Then, the subject of this invention is excellent in surface smoothness, hydrophilic property,
It is an object of the present invention to provide a porous composite sheet having excellent mechanical properties and a production method capable of easily obtaining such a porous composite sheet.

(Means for Solving the Problems) As a result of intensive research to solve such problems, the present inventors have found that by attaching specific fine particles to a composite sheet obtained from short fibers and binder resin, The present invention has been achieved by finding that a porous composite sheet having excellent smoothness, mechanical properties and hydrophilicity can be obtained.

That is, the porous composite sheet of the present invention has a fiber length of 1 mm.
A sheet in which short fibers of ~ 30 mm and a hardened binder are integrated, has continuous pores penetrating from one side of the sheet to the other side, and the porosity of the entire sheet is 40 to 80%, bending strength Is 50 kg / cm ² or more, bending elastic modulus is 1000 kg / cm ² or more,
The water absorption rate is 30 mm / 10 seconds or more, and the water absorption rate is 60% by weight or more.

In addition, the production method of the present invention is a thermosetting resin having an elongation of 3 cm to 15 cm based on 5.3.2 [molding material (disc flow)] of Japanese Industrial Standard JIS-K-6911 ₁₉₇₉ which regulates heat fluidity. A powder is blended with a phenol resin powder and short fibers having a fiber length of 1 mm to 30 mm to form a web, which is then pressed and heated to cure the phenol resin to form a porous composite sheet. The silica-based fine particles having a particle size of 1 μm or less are attached to the porous composite sheet.

Hereinafter, the present invention will be described in detail.

First, the porous composite sheet of the present invention comprises short fibers and a binder, and the short fibers and the cured binder are integrated.

Here, as the short fiber, polyethylene terephthalate fiber, low melting point modified polyester fiber, polyamide fiber such as nylon 6, nylon 66, nylon 46, polyolefin fiber such as polypropylene and polyethylene, kynol fiber (product of Nippon Kynol Co., Ltd.) Examples thereof include synthetic fibers made of organic polymers such as phenol resin fibers (name) and inorganic fibers such as glass fibers and carbon fibers.

The fiber length of the short fibers used in the present invention is 1 mm to 30 mm, preferably 3 to 25 mm, more preferably 5 to 10 mm. When the fiber length exceeds 30 mm, it is difficult to obtain sufficient surface smoothness, while when the fiber length is less than 1 mm, the effect as a reinforcing material cannot be sufficiently exhibited. The fineness of the fiber is preferably 1 to 20 denier.

Next, as the binder in the present invention, for example, a thermosetting resin having a melting point or a softening point of 150 ° C. or lower, or a thermoplastic resin is used. The morphology of these resins is
Used in powder form. Among these, a preferred binder is a phenol resin. As the phenol resin, a thermosetting phenol / aldevid resin obtained by reacting a phenol with an aldehyde, a thermosetting nitrogen-containing phenol obtained by reacting a phenol with an aldehyde and a nitrogen-containing compound, Examples thereof include aldehyde resins.

Next, the sheet of the present invention has continuous pores penetrating from one side of the sheet to the other side. Such continuous pores are bent through the voids of the short fibers constituting the sheet and penetrate from one surface to the other surface, and relatively linearly penetrate from one surface to the other surface. The thing etc. are mentioned.

In the present invention, the presence or absence of continuous pores is determined as follows. First, a disk with a diameter of 10 mm was cut out from a composite sheet with a thickness of 2 mm, and when air was flown through this disk at a rate of 1 Nl / min, it was judged that there were continuous pores when the pressure loss was 2000 mmH ₂ O or less. To do. The smaller the pressure loss when flowing the air, the larger the proportion of the continuous pores in the composite sheet. The above-mentioned pressure loss also represents the degree of breathability of the sheet. In the sheet of the present invention, it is preferable that the pressure loss is 1000mmH 2 _O or less, particularly preferably 300mmH 2 _O or less.

Furthermore, the composite sheet of the present invention has a porosity (%) of 40 to 80.
%.

Here, the porosity (%) represents the ratio of the pore volume to the total volume of the composite sheet as a percentage. The porosity (%) is specifically measured as follows.
First, the dry weight W (g) and volume V (cm ³ ) of the composite sheet
To measure. Next, the sheet is made into a powder and the true density ρ (g / cm ³ ) of the composite sheet is measured, and the porosity (%) is calculated by the following formula.

If the porosity is less than 40%, the proportion of continuous porosity also decreases and the air permeability decreases, which is not preferable. On the other hand, when the porosity exceeds 80%, mechanical properties such as bending strength of the composite sheet tend to be deteriorated, which is not preferable.

Next, the composite sheet of the present invention has a bending strength of 50 kg / cm ² or more and a bending elastic modulus of 1000 kg / cm ² or more. The higher the bending strength, the better, but usually 50 to 300 kg / cm ² is suitable. If the bending strength is less than 50 kg / cm ² ,
It is not preferable because it may be damaged. The higher the flexural modulus, the better, but it is usually 1000 to 10000 kg / cm ² . If the flexural modulus is less than 1000 kg / cm ² , the rigidity tends to be insufficient, which is not preferable.

Here, the bending strength and the bending elastic modulus are JIS-K-7203.
₁₉₈₂ Measured in accordance with the regulations of [Bending test method for hard plastics].

Furthermore, the composite sheet of the present invention has a water absorption rate, that is, a water absorption rate of 30 mm / 10 seconds or more.

Specifically, the water absorption rate is measured as follows. First, from a composite sheet with a thickness of 1 to 5 mm, a width of 20 m
Cut out a plate of m and 150 mm in length. Next, stand this plate vertically in the longitudinal direction and immerse the bottom 30 mm in water.
Read the rising water level in the plate after 10 seconds, and use that value as the water suction speed. If the water uptake rate is less than 30 mm / 10 seconds, it is not preferable because it will be slowed down when used for a water evaporation plate or the like.

Further, the composite sheet of the present invention has a water absorption rate of 60% by weight or more.

Here, the water absorption rate (% by weight) indicates the ratio of water that can be retained by the sheet when the composite sheet is sufficiently immersed in water.

The water absorption rate (% by weight) is specifically measured as follows. First, the dry weight W ₁ (g) of the composite sheet is measured. Next, after fully immersing the sheet in water, pull out from the water to cut off the zero, and weigh W in the wet state.
₂ (g) is measured and even the following formula is calculated.

When the water absorption rate is less than 60% by weight, the amount of water retained becomes small when it is used for a water absorption plate or the like, which is not preferable.

The porous composite sheet of the present invention is preferably manufactured, for example, by the manufacturing method of the present invention.

In the production method of the present invention, first, a thermosetting resin having an elongation of 3 cm to 15 cm based on Japanese Industrial Standard JIS-K-6911 ₁₉₇₉ , 5.3.2 [Molding material (disc flow)], which defines heat fluidity. The wet powder is formed by mixing the powdery granular phenol resin and the short fibers. To form the web, a known carding machine or an apparatus such as an aerodynamic web former may be used. Further, after forming the web, the mat is passed through a calender roll to obtain a mat having a desired thickness.

The above-mentioned Japanese Industrial Standard JIS-K-6911 ₁₉₇₉ , 5.3.2 [Molding material (disc type flow)] is based on the thermal fluidity of the resin and the diameter of the disc-shaped molded product obtained by compression molding the resin. Although this is a test method that evaluates according to the size, concretely, 5 g of phenol resin is placed in a conical shape on a mold maintained at a temperature of 160 ± 3 ° C., and a load of 2500 kgf is applied to this phenol resin at 60 kg.
The disk-shaped molded product is compression molded by applying for 2 seconds, and the diameter of the obtained disk-shaped molded product (the average value of the major axis and the minor axis is the disk diameter) is taken as the elongation of the resin. is there.

The phenolic resin preferably used in the present invention is a thermosetting phenolic resin having a resin elongation measured by such a test method in the range of 3 cm to 15 cm. In the production method of the present invention, when a phenol resin having a thermal fluidity of which the resin elongation is less than 3 cm is used, it is difficult to form the desired porous composite sheet, or even if it can be formed,
Only composite sheets with insufficient mechanical properties tend to be obtained. On the other hand, when a phenolic resin having a thermal fluidity of more than 15 cm is used, the surface part of the porous sheet tends to melt due to pressure and heating, and as a result, the pores with continuous pores Tend to be difficult to obtain a functional composite sheet.

As for the particle size of the powdery particles of the phenol resin used in the present invention, spherical particles having a diameter of 50 to 500 μm or irregular particles of this size are preferably used, but a particle size of 100 to 300 μm is more preferable. . It is also possible to use cylindrical or ellipsoidal powder particles.

The amount of resin mixed with the short fibers is in the range of 10 to 90% by weight, preferably 30 to 70% by weight, based on the weight of the obtained composite sheet. If the amount of the resin is less than 10% by weight, it may be difficult to obtain sufficient mechanical properties. On the other hand, if it exceeds 90% by weight, the porosity decreases and the number of continuous pores decreases. ， The air permeability tends to decrease.

Further, when forming a web, if necessary, a filler such as alumina, silica, talc, carbon black, graphite, molybdenum disulfide, or fluorine resin powder, a pigment or a fungicide as a colorant, a flame retardant, etc. May be added.

Next, the web or mat is pressed and heated to cure the uncured thermosetting phenol resin attached to the short fibers. Pressurization / heating is pressure 1-10kg / cm ² , temperature 140-180
It is preferable to carry out the treatment at a temperature of 150 to 170 ° C. for 3 to 10 minutes, especially at a pressure of 3 to 6 kg / cm ² .

Next, silica-based fine particles having a particle size of 1 μm or less are attached to the porous composite sheet that is pressed and heated and cured. The silica-based fine particles are preferably impregnated by impregnating the porous composite sheet with an aqueous dispersion of silica-based fine particles and drying.

Examples of the silica-based fine particles include fine particles of silicic acid anhydride or hydrous silicic acid. If silica-based fine particles having a particle size of more than 1 μm are used, adhesion unevenness may occur, the binding force with the sheet may be weakened, and a sufficient amount of adhesion may not be obtained, and the water absorption rate and water absorption may tend to decrease. Not preferable.

In the production method of the present invention, the above-mentioned silica-based fine particles are impregnated into the above-mentioned porous sheet as an aqueous dispersion as described above, and as a solvent for dispersing the silica-based fine particles, that is, as a dispersion medium. In addition to water, a solvent such as ethanol, methanol, acetone or methyl ethyl ketone may be used. Among these dispersion media, the water dispersion media are particularly preferable because of their good affinity with the porous sheet, low cost, and easy handling and drying.

The concentration of the dispersion liquid of the above-mentioned silica fine particles is preferably 1 to 40% by weight. If the concentration is less than 1% by weight, the amount of silica fine particles attached to the above-mentioned porous composite sheet will be small, and thus sufficient hydrophilicity may not be obtained, while if the concentration exceeds 40% by weight. However, it is not preferable because the porous composite sheet may be impregnated when impregnated into the porous composite sheet or the silica fine particles may scatter after drying. In addition, in order to improve the adhesion between the silica fine particles and the porous sheet, the dispersion of the silica-based fine particles contains methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, γ-glycidyloxypropyl. A silane coupling agent such as trimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ- (N-β-aminoethyl) aminopropyltrimethoxysilane or γ-aminopropyltrimethoxysilane may be contained, Further, in order to improve the stability of the dispersion liquid, a cationic, anionic, nonionic or other surfactant may be contained.

The amount of silica-based particles attached to the porous composite sheet cured by pressurizing and heating is based on the weight of the porous composite sheet.
It is in the range of 0.01 to 15% by weight, preferably 0.1 to 10% by weight. If the amount of the silica-based fine particles is less than 0.01% by weight, a sufficient water absorption rate may not be obtained, while if it exceeds 15% by weight, the silica-based fine particles may be scattered after drying. .

In order to fix the silica-based fine particles more firmly, it is preferable to heat the porous composite sheet after the silica-based fine particles are attached. Such heat treatment is preferably performed at a temperature of 60 to 110 ° C. for about 10 to 60 minutes.

Thus, a sheet composed of short fibers and phenol resin, in which short fibers and hardened phenol resin are integrated, has continuous pores penetrating from one side of the sheet to the other side, Of 40 to 80%, bending strength of 50 kg / cm ² or more, bending elastic modulus of 1000 kg / cm ² or more, water absorption rate of 30 mm / 10 seconds or more, water absorption rate of 60% by weight or more A good porous composite sheet is formed. Usually, the surface of the composite sheet is covered with the thermosetting phenol resin except for the portion where the continuous pores penetrate by the pressurization and heating.

The phenol resin preferably used in the present invention is
For example, it can be produced by reacting a phenol or nophoric resin with an aldehyde in the presence of a suspension stabilizer and a basic compound in an aqueous medium. Examples of such phenols include phenol derivatives in addition to phenol. Examples of the phenol derivative include, for example, m-alkylphenol, o-alkylphenol and p-alkylphenol substituted with an alkyl group having 1 to 9 carbon atoms, specifically m-cresol, p-tert-butylphenol, o. -Propylphenol, resorcinol, bisphenol A, and halogenated phenol derivatives in which some or all of the hydrogen atoms of these benzene nuclei or alkyl groups are substituted with chlorine or bromine.
The phenols are not limited to these, and any other compound having a phenolic hydroxyl group can be used. Also, two or more kinds of these phenols can be used.

In the presence of an acid catalyst such as novolak resin, oxalic acid, hydrochloric acid or sulfuric acid used for producing the above-mentioned phenol resin, the above-mentioned phenols are mixed with aldehydes in an amount of 1: 1.
It is a thermoplastic resin having a linear molecular structure obtained by reacting with a molar ratio to 1 or less, and a solid resin having a melting point of 70 to 100 ° C. measured by a ring and ball method. Such novolak resin can be easily obtained as a commercial product.

Further, examples of aldehydes used for producing the phenol resin include formaldehyde, acetaldehyde, as well as formalin, paraformaldehyde, furfural and the like.

The amount of aldehydes to be used with respect to the phenols is preferably 1 to 2, particularly 1.1 to 1.4 in terms of molar ratio. The amount of aldehydes used with respect to the novolak resin is preferably 50% by weight or less.

Further, examples of the suspension stabilizer used for producing the above-mentioned phenol resin include substantially water-insoluble inorganic salts or water-soluble organic polymers. As the substantially water-insoluble inorganic salts, for example, calcium fluoride, magnesium fluoride, strontium fluoride and the like are preferable. As a method for adding such a substantially water-insoluble inorganic salt, such a substantially water-insoluble inorganic salt may be added directly to the reaction system, but such a substantially water-insoluble inorganic salt may be added during the reaction for producing the phenol resin. Two or more kinds of water-soluble inorganic salts that can form insoluble inorganic salts may be added.

Examples of the water-soluble inorganic salts capable of forming substantially water-insoluble inorganic salts include, for example, at least one selected from the group consisting of sodium fluoride, calcium fluoride and ammonium fluoride, calcium, magnesium and strontium. And at least one selected from the group consisting of chloride, sulfate and nitrate.

Examples of the water-soluble organic polymer include gum arabic, glutinous gum, hydroxyguar gum, partially hydrolyzed polyvinyl alcohol, hydroxyethyl cellulose,
Examples include carboxymethyl cellulose, soluble starch and agar. Such water-soluble organic polymers can be used alone or in combination. Further, a substantially water-insoluble inorganic salt and a water-soluble organic polymer may be used in combination.

Examples of the basic compound include caustic soda, caustic potash, calcium hydroxide, magnesium hydroxide, aqueous ammonia, hexamethylenetetramine, dimethylamine, diethylenetriamine and polyethyleneimine, with aqueous ammonia or hexamethylenetetramine being particularly preferred. Such basic compounds can be used alone or in combination.

As the aqueous medium used for producing the phenol resin used in the present invention, water containing an organic solvent may be used in addition to water. The amount of the aqueous medium used is preferably such that the solid content of the resulting phenol resin is 20 to 70% by weight, particularly 30 to 60% by weight.

The reaction temperature for producing the phenol resin according to the present invention is preferably 70 to 100 ° C, particularly 80 to 95 ° C. The reaction time is preferably 20 to 120 minutes, especially 40 to 90 minutes.

After completion of the reaction, the reaction product is cooled to 40 ° C. or lower, the solid liquid is separated by filtration or centrifugation, further washed with water and dried.

(Examples) Hereinafter, the present invention will be specifically described with reference to Examples.

In a three-necked flask of Reference Examples 1 to 41, 200 g of phenol, 20 g of 37 wt% formaldehyde aqueous solution (formalin), 70 g of water,
Hexamethylenetetramine 18g and calcium chloride 6.7
While stirring, add g to make a uniform solution, add 32 g of a 10 wt% aqueous solution of sodium fluoride under stirring to the solution, and then heat the contents to 85 ° C over 60 minutes and maintain this temperature. While stirring was continued.

After the temperature of the contents reaches 85 ℃, 10 minutes, 40 minutes, 90
At 50 minutes and 150 minutes, 50 g of the content was sampled. 0.3 after cooling each sampling to 30 ° C
Water was added. Then, after removing the supernatant liquid, the microsphered resin in the lower layer was washed with water and dried, and further dried at 50-60 ° C under a reduced pressure of 5 mmHg or less to obtain a phenol resin having an average particle size of about 70 µm. It was These phenolic resins are referred to as resins A, B, C and D, respectively.

In a glass flask of Reference Examples 5 to 71, 200 g of novolak resin [Mitsui Toatsu Chemicals, Inc. # 6000 (melting point: 70 to 76 ° C.)], 200 g of water, 150 g of water and 4 g of gum arabic were charged, and the contents were stirred to 95%.
Heated to ° C. Hexamethylene tetramine 20g
A solution dissolved in 150 g of water was added, and stirring was continued while maintaining the temperature at 95 ° C.

After adding an aqueous solution of hexamethylenetetramine, 50 g of each of the contents was sampled at 10 minutes, 60 minutes and 150 minutes. After cooling each sampling to 30 ° C
0.3 of water was added, and the microsphered resin was filtered off with filter paper, then washed with water, air-dried, and further dried under reduced pressure of 5 mmHg or less at 35 ° C. for 24 hours, and a phenol resin having an average particle diameter of about 200 μm. Got These phenolic resins are referred to as resins E, F and G, respectively.

Examples 1 to 4, Comparative Examples 1 to 3 The elongations of the above resins A to G were measured based on the JIS standard. The results are shown in Table 1.

10 kg of each of the above resins A to G and 20 kg of polyethylene terephthalate short fibers (average fiber length 5 mm, average fineness 4 denier)
And wet with a carding machine,
By passing the calender roll set at ℃, the thickness
A mat with a width of 50 cm and a basis weight of 10 mm and a weight of 800 g / m ² was obtained.

By pressurizing and heating these at a pressure of 1 kg / cm ² for 5 minutes using a press molding machine preheated to a temperature of 170 ° C.,
The phenol resin was cured to obtain a composite sheet with a thickness of 2 mm.

Further, 20 g of finely powdered silicic acid anhydride having a particle size of 0.1 μm was dispersed in 180 g of water to obtain an aqueous dispersion of finely powdered silica-based particles.

The above-mentioned cured sheet was impregnated with the above-mentioned fine powder silicic acid anhydride dispersion, and then dried at 100 ° C. for 20 minutes to obtain a composite sheet impregnated with the fine powder silicic acid anhydride. At this time, the amount of finely powdered silicic acid impregnated was in the range of 0.5 to 3% by weight.

These sheets are made to correspond to the phenolic resins A to G, respectively, to form composite sheets A _{1 to} G ₁ .

Comparative Example 4 A composite sheet was obtained in the same manner as in Example 2 except that silicic acid anhydride having a particle diameter of 2.5 μm was used as the fine powder silica particles.
This sheet is referred to as a composite sheet H ₁ . The amount of the silicic acid powder impregnated at this time was 0.03% by weight.

Comparative Example 5 As the short fibers of polyethylene terephthalate, short fibers having an average fiber length of 40 mm and an average fineness of 4 denier were used.
A composite sheet was obtained in the same manner as in Example 2. This sheet is referred to as a composite sheet I ₁ .

Table 2 shows the results of measuring the surface smoothness, the porosity, and the flexural strength and flexural modulus of the composite sheets A _{1 to} I ₁ based on the JIS standard.

The surface smoothness is the result of the sensitivity test.

○… Smooth texture ×… Rough texture As is clear from Table 2, the porosities of the composite sheets A _{1 to} I ₁ were all 60 to 65%. However, regarding bending strength, A ₁ , B ₁ , C ₁ , E ₁ , F ₁ , H ₁ , I
_Although the composite sheet of _{No. 1} had practically sufficient bending strength,
The composite sheets D ₁ and G ₁ were not practical.

Next, composite sheets A ₁ and B cut out into discs with a diameter of 10 mm
Air was flown through ₁ , C ₁ , F ₁ , E ₁ , and H ₁ at a rate of ₁ N / min, the pressure loss was measured by the above method, and the presence or absence of continuous pores was examined.

In the case of the comparative composite sheet A ₁ , the pressure loss when air was flowed at a rate of 1 N / min was so large that it could not be measured. This indicates that the composite sheet A ₁ does not have continuous pores. Further, as is clear from Table 3, the composite sheets B ₁ , C ₁ , F ₁ according to the present invention,
E ₁ and the composite sheet H ₁ of Comparative Example 4 had a low pressure loss of 300 or less when air was flowed at a rate of 1 N / min, and had continuous pores. When the composite sheets of Examples 1 to 4 and Comparative Example 4 according to the present invention were examined, most of the pores were continuous pores.

Next, the water uptake rate and the water absorption rate of the composite sheets B ₁ , C ₁ , F ₁ , E ₁ , and H ₁ cut out into a plate having a width of 20 mm and a length of 150 mm were measured. The results are shown in Table 4.

As is clear from Table 4, in the case of the comparative composite sheet H ₁ , the water absorption rate was 35% by weight and the water absorption rate was 5 mm / 10.
Seconds, indicating that the hydrophilicity is poor. However, the composite sheets B ₁ , C ₁ , E ₁ , and F ₁ according to the present invention have a water absorption rate of 65 to 80% by weight and a water absorption rate of 35 to 65 mm / 10 seconds, and have sufficient hydrophilicity. It was

(Effects of the Invention) The porous composite sheet of the present invention is formed by integrating short fibers and binder resin, and therefore has excellent mechanical properties such as bending strength and bending elastic modulus, and particularly has a high bending elastic modulus. Shows excellent rigidity. Moreover, since short fibers are used, the surface smoothness is good.

Furthermore, since it has a high porosity, it is lightweight and easy to handle. Furthermore, since it has continuous pores, it has excellent breathability. Moreover, since the porosity is high, there are also many continuous pores. Furthermore, it has a high water absorption rate and a high water absorption rate.

Therefore, it can be used as an air diffuser, a filter medium, a water absorbing plate, a water evaporating plate, etc., especially an air conditioner,
It can be suitably used as a humidity control plate for electric refrigerators, refrigerating vending machines, etc., and a vaporization plate for drain water, and also as a molding material such as a molding material for ceramic slurries that require the above-mentioned mechanical characteristics. It can be preferably used and can be used for a wide range of purposes.

Further, in the production method of the present invention, since the thermosetting phenol resin having a specific heat fluidity is used, the porous composite sheet can be easily obtained by a simple operation.

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Claims (2)

[Claims] 1. A sheet in which a short fiber having a fiber length of 1 mm to 30 mm and a cured binder are integrated, having continuous pores penetrating from one surface of the sheet to the other surface, and pores of the entire sheet. Modulus of 40 to 80%, bending strength of 50 kg / cm ² or more, bending elastic modulus of 1000 kg / cm ² or more, water absorption rate of 30 mm / 10
A porous composite sheet with excellent surface smoothness, which has a water absorption rate of 60% by weight or more for a second or more. 2. Japanese Industrial Standard JIS- which regulates heat fluidity
According to K-6911 ₁₉₇₉ , 5.3.2 [Molding material (disc type flow)], a thermosetting phenolic resin powder having an elongation of 3 cm to 15 cm and short fibers having a fiber length of 1 mm to 30 mm are mixed. To form a web, and then pressurize and heat to cure the phenol resin to form a porous composite sheet, and then to attach the silica-based fine particles having a particle size of 1 μm or less to the porous composite sheet. A method for producing a porous composite sheet having excellent surface smoothness.