JPH06104750B2 - Method for producing porous molded body made of phenolic resin - Google Patents

Description

TECHNICAL FIELD The present invention relates to an economical method for producing a phenol resin porous molded article having excellent air permeability, heat resistance and solvent resistance.

(Prior Art) Conventionally, there is known a method for producing a porous molded body having continuous pores by sintering and molding fine particles of an organic polymer such as polyethylene, polypropylene, polystyrene, polymethylmethacrylate and polyacrylonitrile. However, these porous molded bodies are widely used for applications such as air diffusers, filter media, and printing rollers.

These porous molded bodies have a problem that the organic polymer used as a material of the porous molded body has a problem that heat resistance and solvent resistance are inferior.

Therefore, it has been proposed in JP-A-60-152532 to use a phenol resin having excellent heat resistance and solvent resistance. This method involves casting a mixed solution of polyvinyl alcohol, a water-soluble thermosetting resin, and a reactive granular or powdered phenol resin together with a curing agent to cure the mixture, and then removing it from the mold and then polyvinyl alcohol. Is washed with water to produce a porous molded body. This method is not a method of directly sintering and molding a phenol resin, but a method of directly sintering and molding a phenol resin has not been known.

(Problems to be Solved by the Invention) The above-mentioned conventional method has a problem in that it is not practical because the operation is complicated and it takes a long time to wash out polyvinyl alcohol.

It is an object of the present invention to provide a method for producing a phenol resin porous molding having excellent mechanical strength, air permeability, heat resistance and solvent resistance in a simple operation and a short molding time.

(Means for Solving the Problems) The inventors of the present invention have made earnest studies to solve such problems, and as a result, by using a phenol resin having a specific heat fluidity, a simple operation and a short molding can be performed. The present inventors have found that a porous molded article having excellent mechanical strength and air permeability can be economically produced over time, and have reached the present invention.

That is, the present invention is based on Japanese Industrial Standard JIS K 6911 _-1979.
5.3.2 [Molding material (disc flow)], a method for producing a product for producing a porous molded product of a phenolic resin, characterized by sintering and molding a phenolic resin having a resin elongation of 3 to 10 cm. It is a summary.

The phenol resin used in the present invention can be produced by reacting a phenol or novolac resin with an aldehyde in an aqueous medium in the presence of a suspension stabilizer and a basic compound.

Examples of phenols include not only phenol but also phenol derivatives. As a phenol derivative,
For example, m-alkylphenol, o-alkylphenol, p-alkylphenol substituted with an alkyl group having 1 to 9 carbon atoms, specifically, m-cresol, p-ter-butylphenol, o-propylphenol, resorcinol ，
Examples thereof include 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. In addition,
The phenols are not limited to these, and any other compound having a phenolic hydroxyl group can be used.
Any compound can be used.

Also, two or more of these phenols can be used.

The novolak resin used for producing the phenol resin in the present invention is obtained by adding the above-mentioned phenols to the aldehydes in a molar ratio of 1: 1 or less in the presence of an acidic catalyst such as oxalic acid, hydrochloric acid or sulfuric acid. It is a thermoplastic resin with a linear molecular structure obtained by reacting with, and is a solid resin with a melting point of 70-100 ° C measured by the ring and ball method.

Such novolac resin can be easily obtained as a general commercial product.

Examples of aldehydes used for producing the phenol resin in the present invention include formaldehyde, acetaldehyde, formalin, paraformaldehyde, and furfural.

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

Examples of the suspension stabilizer used for producing the phenol resin in the present invention include substantially water-insoluble inorganic salts or water-soluble organic polymers.

As the substantially water-insoluble inorganic salt, 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, potassium fluoride and ammonium fluoride, and calcium, magnesium, strontium. At least one selected from the group consisting of a chloride, a sulfate and a nitrate of tuum can be used.

Examples of the water-soluble organic polymer include gum arabic, gatch 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.

In addition, 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, ammonia water, hexamethylenetetramine, dimethylamine, diethylenetriamine and polyethyleneimine, and ammonia water or hexamethylenetetramine is particularly preferable. Such basic compounds can be used alone or in combination.

The aqueous medium used for producing the phenol resin in the present invention may be not only water but also water containing an organic solvent.

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 in the present invention is preferably 70 to 100 ° C, particularly preferably 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.

The phenolic resin used in the present invention is a Japanese Industrial Standard JIS
It is a thermosetting phenolic resin in which the elongation of the resin measured by the method specified in 5.3.2 of K _6911-1979 [molding material (disc type flow)] is in a specific range.

According to Japanese Industrial Standard JIS K 6911 _-1979 , 5.3.2 [Molding material (disc flow)], the elongation of resin is evaluated by the size of the diameter of the disc-shaped molded product obtained by compression molding the resin. Although it is a test method, specifically, a cone is placed on a mold in which 5 g of phenol resin is kept at a temperature of 160 ± 3 ° C.
A disk-shaped molded product is compression-molded by applying a load of 2500 kgf to this phenol resin for 60 seconds, and the diameter of the obtained disk-shaped molded product (the average value of the major axis and the minor axis is defined as the disk diameter). ) Is the elongation of the resin.

The phenolic resin 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 to 10 cm.

In the method for producing the porous molded article of the present invention, the elongation of the resin is
If a phenolic resin with a thermal fluidity of less than 3 cm is used, is it difficult to form the desired porous molded article?
Even if it can be molded, it tends to yield only a porous molded body with weak mechanical strength. In addition, when a phenolic resin having a thermal fluidity of more than 10 cm is used, the surface of the porous molded body that is in contact with the mold tends to melt during molding. It tends to be difficult to obtain a porous molded article having good quality.

As the form of the phenol resin used in the present invention, any shape such as spherical, plate-like, and amorphous can be used as long as it is solid, but the shape is particularly preferable. Also,
When the particle size of the phenol resin is large, the mechanical strength of the porous molded body obtained by the production method of the present invention tends to be small, and therefore, it is preferably 1000 μm or less.

In the production method of the present invention, various shapes of porous molded articles can be molded by filling the mold with the thermosetting phenolic resin having the above-mentioned resin elongation and heating while applying pressure.

The porous molded article referred to in the present invention has continuous pores and has a porosity of at least 1%.

As the molding conditions for the porous molded body in the present invention, conventionally known molding conditions for the porous molded body can be adopted.

The molding conditions for such a conventionally known porous molded article are 0.01 to 10 kg / cm ² , 50 to 1 for molding pressure, molding temperature, and molding time, respectively.
80 ℃, 5 to 100 minutes.

Molding conditions such as molding pressure, molding temperature, molding time, etc.
It can be appropriately selected according to the size of the particles of the phenol resin used, the porosity and the size of the pores of the desired porous molded article, or the shape of the molded product.

(Examples) The present invention will be described below with reference to Examples.

Reference Examples 1-4 In a 1-liter three-necked flask, 200 g of phenol and 37 wt%
Formalin 200g, Water 70g, Hexamethylenetetramine 18g
And 8.4 g of calcium chloride with stirring to form a uniform solution.
After adding 40 g of wt% solution, heat the contents to 85 ° C. over 60 minutes and continue stirring while maintaining this temperature.

10 minutes, 40 minutes, 90 minutes and 15 minutes after the temperature of the contents reaches 85 ℃
At 0 minutes, sample 50g of contents. After cooling each sample to 30 ° C, 0.3 liter of water is added. After removing the supernatant, the microsphered resin in the lower layer was washed with water, air-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 50 microns. These phenolic resins are referred to as resins A, B, C and D, respectively.

Reference Examples 5 to 7 In a 1 liter glass flask, 200 g of novolac resin [Mitsui Toatsu Co., Ltd. # 6000 (melting point 70 to 76 ° C.)], water 150
g and arabic gum 4 g, and while stirring, contents 9
Heated to 5 ° C. Hexamethylene tetramine 20g to this
A solution dissolved in 150 g of water was added, and the temperature was kept at 95 ° C, and stirring was continued.

10 minutes after adding the aqueous solution of hexamethylenetetramine, 6
Sample 50g of contents at 0 and 150 minutes. After cooling each sample to 30 ° C, 0.3 liters of water was added and the finely spheroidized resin was filtered off using a paper filter, washed with water, air-dried, and further dried at 35 ° C for 24 hours under reduced pressure of 5 mmHg or less. As a result, a phenol resin having an average particle size of about 200 microns was obtained. These phenolic resins are designated as resins E, F and G, respectively.

Examples 1 to 3 and Comparative Examples 1 to 4 The elongations of the resins of Resins A to G were measured based on JIS K 6911. The results are shown in Table 1.

85 g of each of the resins A to G is filled in a mold having a cylindrical cavity with a diameter of 25 mm and a height of 100 mm, and 80 is applied under a pressure of 100 kg / cm ^2.
The temperature was raised from 20 ° C to 180 ° C over a period of time. When the contents were taken out after cooling, when Resins D and G were used, the contents were not sufficiently fused and collapsed when taken out from the mold.

When the resins B, C and F were used, a porous molded article having a good appearance was obtained.

When resins A and E were used, they did not collapse when the molded product was taken out of the mold, but when the surface of this molded product was observed 300 times using an optical microscope, the phenol resin The particles were fused to each other and few pores were observed.

The porosities of the porous molded articles obtained from the resins B, C and F were 35, 38 and 37%, respectively.

The compressive strength of the porous molded body obtained from the resins B, C and F is J
When measured by the method specified in IS K 6911,
It was 150, 180 and 110 kg / cm ² , and had mechanical strength sufficient for practical use.

In addition, 20g / cm ^{2 of} 3.1g of each of Resins A to G was filled into a mold with a disk-shaped cavity with a diameter of 30mm and a height of 5mm.
The temperature was raised from 20 ° C to 150 ° C over 50 minutes under pressure. When the contents were taken out after cooling, when Resins D and G were used, the contents were not sufficiently fused and collapsed when taken out from the mold.

When the resins A, B, C, E and F were used, molded articles were obtained, so the air permeability of these molded articles was measured. The air permeability of the compact was expressed as the amount of pressure required to flow air at a constant rate (1 Nl / min.) Through the compact. The results are shown in Table 2.

In the case of molded products using resins A and E, the pressure required to flow air at a rate of 1 Nl / min. Was extremely large and could not be measured because the molded products had poor air permeability. .

As is clear from the values of pressure when the resins B, C and F are used, such a molded product has a breathability suitable for practical use.

(Effect of the Invention) According to the production method of the present invention, a porous molded article of a phenol resin having excellent mechanical strength and air permeability can be produced very easily. Further, since the porous molded article obtained by the production method of the present invention uses a phenol resin, it has excellent heat resistance and chemical resistance. The porous molded body of the phenol resin obtained by the production method of the present invention can be used for air diffusers, various filtering materials, printing rollers, etc. by utilizing the above characteristics.

Claims (1)

[Claims] 1. Japanese Industrial Standard JIS K 6911 _-1979 5.3.2
Resin elongation based on [molding material (disc flow)] is 3 to 10
A method for producing a porous molding made of a phenol resin, which comprises sintering a phenol resin having a size of cm.