JPS6320455B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention involves the production of a porous polymer material having fine continuous pores by mixing polyvinyl alcohol, a water-soluble thermosetting resin, and a reactive granular or powdered phenolic resin, and adding a curing agent to react and cure the mixture. Regarding the law. Conventionally, polyvinyl acetal-based porous materials have been produced by a so-called acetalization reaction in which polyvinyl alcohol mixed with starch or other pore-forming materials is reacted with aldehydes using an acid catalyst, and due to its continuous pore characteristics and high porosity, it has excellent properties. It has been used as a filler material. However, with the recent advances in overfill technology, the performance requirements for overfill materials are becoming increasingly strict, and even the currently widely used cartridge-type overfill materials have high strength and excellent heat resistance.
There is a growing demand for a device with high precision and overperformance. However, in the conventional manufacturing method of polyvinyl acetal-based porous materials, the pore diameter of the porous material is limited by the particle size of the pore-forming material, so it is necessary to manufacture a highly precise overmaterial that can remove fine particles of, for example, 1 μm or less. The current situation is that this is difficult. In addition, the polyvinyl acetal porous material is
Since it swells due to moisture absorption, it has poor shape retention and requires resin treatment to improve this, and it also has other drawbacks such as poor heat resistance. The present inventors completed the present invention as a result of intensive research to improve the above-mentioned drawbacks of conventional polyvinyl acetal porous materials. It is an object of the present invention to provide a new method for producing a porous polymer material having continuous pores and having excellent strength and heat resistance. The above object is achieved by mixing polyvinyl alcohol, a water-soluble thermosetting resin, and a reactive granular or powdery phenol resin, adding a curing agent, and curing the mixture by reaction. A remarkable feature of the present invention is that pores can be formed through the interaction of polyvinyl alcohol, a water-soluble thermosetting resin, and a reactive granular or powdery phenolic resin, without using a pore-forming material as in the past. By changing the mixing ratio of these components, the pore morphology and pore size distribution can be controlled to produce a polymeric porous body having fine and uniform continuous pores. The polyvinyl alcohol used in the present invention is generally obtained by saponifying vinyl acetate, and there are no particular restrictions on its degree of polymerization, degree of saponification, branching, copolymerization with other monomers, etc., and it can be used alone or as a mixture of two or more. However, it is preferable that the degree of polymerization
100 to 5000, preferably with a saponification degree of 70 mol% or more. In addition, as a water-soluble thermosetting resin,
Water-soluble resol resins, melamine resins, urea resins, etc. are suitable. Resole resin is an initial product obtained by reacting phenols with aldehydes in the presence of a basic catalyst, and is usually a self-thermal crosslinking phenol resin with a molecular weight of about 600 or less and rich in methylol groups. In general, water-soluble resol resins are obtained by keeping the initial condensate obtained by reacting 1.5 to 3.5 moles of aldehyde with 1 mole of phenol in the presence of a slightly excess alkali catalyst in a stable water-soluble state. . Melamine resin and urea resin are initial condensates of melamine-formaldehyde and urea-formaldehyde, respectively, and are water-soluble. In the present invention, the curing agent includes a curing catalyst for curing water-soluble thermosetting resin, and curing agents for phenolic resin include hydrochloric acid,
Oxalic acid, lactic acid, formic acid, acetic acid, para-toluenesulfonic acid, benzelsulfonic acid, etc. are suitable, and as curing agents for melamine resin and urea resin, inorganic acids such as hydrochloric acid and sulfuric acid, and carboxylic acid esters such as oxalic acid dimethyl ester are suitable. Hydrochlorides of amines such as ethylamine hydrochloride and triethanolamine hydrochloride can be used. In addition, these curing agents may be used in combination with a polyvinyl alcohol crosslinking agent such as formaldehyde or benzaldehyde, especially when the amount of polyvinyl alcohol blended is large compared to the water-soluble thermosetting resin. It is desirable to use them together. In addition to the above-mentioned crosslinking agents for polyvinyl alcohol, aldehydes such as acetaldehyde, propionaldehyde, 0-butyraldehyde, octylaldehyde, 2-ethylhexylaldehyde, glyoxal, and acrolein can be used. Furthermore, the reactive granular or powdered phenolic resin of the present invention is a granular or powdered resin made of a condensate of phenols and formaldehyde, and the infrared absorption spectrum of the resin measured by the KBr tablet method is 1600 cm ^{- 1} (absorption peak attributed to benzene) D ₁₆₀₀ , 990 to 1015 cm ^-1 (absorption peak attributed to methylol group)
The largest absorption intensity in the range of D _990~1015 , 890cm
^-1 (absorption peak of isolated hydrogen atom of benzene nucleus)
When the absorption intensity is expressed as D ₈₀₀ , D _{990 ~ 1015} / D ₁₆₀₀ = 0.2 ~ 9.0, D ₈₉₀ / D ₁₆₀₀ = 0.09 ~
It is a granular or powdered phenol-formaldehyde resin with a value of 1.0, preferably D _{990 - 1015} / D ₁₆₀₀ = 0.3 - 7.0, D ₈₉₀ / D ₁₆₀₀ = 0.1 -
0.9 Particularly preferably D990 _~1015 / _D1600 =0.4~5.0, _D890 / _D1600 =0.12~
It is a granular or powdered phenol/formaldehyde resin with a molecular weight of 0.8. In the infrared absorption spectrum, the peak at D ₁₆₀₀ indicates absorption attributed to the benzene nucleus, and the peak at D _{990 to 1015}
The peak of shows the absorption attributed to the methylol group,
Furthermore, it is already widely known for phenol formaldehyde resins that the D ₈₉₀ peak shows absorption attributed to isolated hydrogen atoms in benzene nuclei. The fact that the reactive granular or powdery phenolic resin used in the present invention exhibits a characteristic value of _D990-1015 / _D1600 = 0.2-9.0 means that the resin contains at least a certain amount of methylol groups. , showing that its methylol group content can be adjusted to a fairly wide range. In particular, the resin suitable for use in the present invention with _D990-1015 = 0.3-7.0, especially 0.4-5.0 contains a moderate concentration of methylol groups and is more stable. Furthermore, the resin has D ₈₉₀ /D ₁₆₀₀ = 0.09 to 1.0 in the infrared absorption spectrum, and a more suitable resin is
The fact that the resin exhibits a characteristic of D ₈₉₀ /D ₁₆₀₀ = 0.1 to 0.9, especially 0.12 to 0.8, indicates that the reaction sites (ortho and para positions) of the phenol molecules involved in the reaction are considerably composed of methylene bonds or methylol groups. This shows the fact that it is moderately blocked by Cured products of conventionally known resol resins are generally
Both or one of D _{990 to 1015} /D ₁₆₀₀ and D ₈₉₀ /D ₁₆₀₀ is lower than the lower limit of the above characteristic value of the reactive granular or powdered phenolic resin used in the present invention, and the hexamine of the novolac resin is The cured product also generally has a characteristic value of D ₈₉₀ /D ₁₆₀₀ that is lower than the lower limit of 0.09 for the resin.
As described above, the reactive granular or powdered phenolic resin used in the present invention is obtained by pulverizing a conventionally known cured resol resin product or a cured novolac resin product, or by pulverizing a conventionally known cured novolak resin fiber. It is a phenolic resin made of spherical primary particles and secondary aggregates thereof, which is produced according to the manufacturing method described in JP-A-57-177011. Since this reactive granular or powdered phenolic resin has a shape close to spherical, it is more likely to be heat cured with polyvinyl alcohol or water soluble than the powder obtained by pulverizing a known cured phenolic resin. It has good miscibility with synthetic resins,
By using this resin, it becomes possible for the first time to obtain a porous polymer body having continuous pores in which a large amount of phenolic resin powder is uniformly mixed. In order to uniformly disperse the phenolic resin powder in the porous polymer, the average particle size of the phenolic resin powder is preferably 1 to 150 μm. In order to produce a porous polymer material having fine continuous pores using the above-mentioned polyvinyl alcohol, a water-soluble thermosetting resin, and a reactive granular or powdered phenolic resin, it is necessary to add an appropriate amount to a predetermined amount of polyvinyl alcohol. After adding water and heating to dissolve,
A water-soluble thermosetting resin and a reactive granular or powdered phenolic resin that has been previously dispersed in water are added and stirred, and after cooling to about 40°C, a curing agent is added and mixed uniformly to achieve the desired Transfer it to a mold of the shape of and heat it to cause a reaction. After the reaction is completed, the molded product taken out from the mold may be washed with water to wash away unreacted substances, curing agent, etc. The shape of the molded product can be freely selected from plate, cylinder, cylindrical, etc. When producing a polymeric porous body with fine continuous pores by the above method, the blending amounts of polyvinyl alcohol, water-soluble thermosetting resin, and reactive granular or powdery phenolic resin are determined by the curing agent. The solid content concentration in the mixed liquid before mixing is usually 0.5 to 15% by weight of polyvinyl alcohol, 3 to 55% by weight of water-soluble thermosetting resin, and 5% of reactive granular or powdered phenolic resin. -30% by weight, preferably 1-12% by weight of polyvinyl alcohol, 5-45% by weight of water-soluble thermosetting resin, and 8-28% by weight of reactive granular or powdered phenolic resin. most preferably polyvinyl alcohol
8% by weight, 8 to 40% water-soluble thermosetting resin
The amount of reactive granular or powdered phenolic resin is 10 to 25% by weight. In producing the porous polymer material having fine continuous pores of the present invention, the advantage of mixing reactive granular or powdered phenolic resin is that by uniformly dispersing the phenolic resin powder,
It is possible to form fine and uniform continuous pores without using a pore-forming material. Further, the phenolic resin powder contributes to the development of strength of the porous body by reacting with the water-soluble thermosetting resin during the curing reaction process. If the amount of the phenolic resin powder mixed in is too small, the pore distribution becomes non-uniform, causing problems such as large voids being likely to be formed inside the sample during the curing reaction, and cracks being likely to occur during the drying process after the curing reaction. Furthermore, the number of independent pores increases, making it difficult to obtain a porous polymer having a high continuous porosity. If the amount of the resin powder is too large, the resin powder becomes bulky, and the workability when mixing with other materials is significantly reduced, making it difficult to mix uniformly and making it impossible to obtain a good porous body. Polyvinyl alcohol imparts a unique pore morphology to the porous polymer through interaction with reactive granular or powdered phenolic resin, and plays an important role in the formation of fine continuous pores. If polyvinyl alcohol is too small, not only the pore morphology changes, but also the pore distribution tends to become non-uniform. On the other hand, if the amount is too high, the viscosity of the liquid mixture will increase and the workability will be significantly lowered, making it impossible to obtain a good porous body. Furthermore, if the water-soluble thermosetting resin is too small, the bonding strength between the granular or powdery phenolic resins in the obtained porous polymer will be low;
A good porous polymer material with high strength cannot be obtained. Too much liquid phenolic resin is not preferred because the number of closed pores increases and the continuous porosity decreases. In addition, when manufacturing the above-mentioned porous polymer having fine continuous pores, resin powders such as phenolic resin, furan resin, and epoxy resin, fibrous materials, or inorganic materials such as silica, alumina, graphite, silicon carbide, and viscosity may be used. A suitable amount of powder, carbon fiber, fibrous material such as asbestos may be mixed. In addition to the porous polymer obtained as described above, phenolic resins such as resol resins and novolac resins, furan resins, melamine resins, epoxy resins, etc.
It may be impregnated with or adhered to urea resin, pitch, tar, etc. Various known methods can be applied to apply these synthetic resins, but most commonly, fine particles with a predetermined shape, size, pore diameter, and porosity manufactured by the above-mentioned method are used. A porous polymer body having continuous pores may be immersed in a solution prepared by dissolving the above-mentioned synthetic resin or the like in a solvent, and then dried and cured. The polymer porous body of the present invention thus obtained has uniform, fine, continuous pores, and a porous body with an average pore diameter of 10 μm or less can be easily obtained.
Particularly when the amount of solids in the mixed liquid during production is large, the polymer porous material has extremely fine continuous pores with an average pore diameter of 1 μm or less. Further, the porous polymer material has the characteristics of high strength and high porosity. A porous polymer material having such excellent properties is ideal as a filter for passing fine particles. Separation of fine particles such as dust and impurities in gases,
Depth-type filters used for separating fine particles in liquids are usually a fraction of the average pore diameter.
The filter of the present invention is also suitable as a high-precision precision filter that passes fine particles of 1 μm or less. In addition, the polymer porous body uses a thermosetting resin,
High strength and excellent heat resistance. The porous polymer material having fine continuous pores of the present invention is suitable not only as a filter but also as a heat insulating material, a catalyst carrier, an aeration pipe, etc. The present invention will be explained in more detail below using Examples. Example 1 A predetermined amount of polyvinyl alcohol (degree of polymerization 1700,
saponification degree of 99%) was dispersed in water and dissolved by heating.
Add a water-soluble resol resin (manufactured by Showa Union Gosei Co., Ltd., BRL-1583 (solid content concentration 70% by weight)) to this solution and a predetermined amount of reactive granular phenol resin (Kanebo Co., Ltd.) that has been dispersed in water in advance. Co., Ltd., trade name: Bell Pearl S, average particle size 20 μm) was added thereto and thoroughly stirred and mixed. Water for liquid volume adjustment was added to this mixed liquid to adjust the mixed liquid volume to 10 kg. The amount of each component in the mixed solution was measured in advance as shown in Table 1. Add an appropriate amount of formalin (37% by weight) to the above mixture.
and para-toluenesulfonic acid aqueous solution (50% by weight)
After adding and stirring further, it was poured into a 300 mm square polypropylene mold and reacted for 20 hours in a hot water bath at 75 °C. After demolding, it was washed with a shower for 4 days and dried at 80 °C to form a fine mold. A porous polymer material having continuous pores was obtained. Table 1 shows the properties of the porous polymer material having fine continuous pores thus obtained. The average pore diameter of the porous polymer material was measured by mercury intrusion method. Further, the continuous porosity was measured using an air comparison type hydrometer. As can be seen from this example, by appropriately selecting the blending ratio of liquid phenolic resin, reactive particulate phenolic resin, and polyvinyl alcohol, a porous polymer body having fine continuous pores was obtained.

[Table] Example 2 An outer diameter of 70 mm was prepared in the same manner as in Example 1 from polyvinyl alcohol with a degree of polymerization of 500 and a degree of saponification of 99%, a water-soluble thermosetting resin, and phenol resin powder.
A cylindrical porous polymer body with an inner diameter of 30 mm and a length of 250 mm was prepared. Examples of water-soluble thermosetting resins include melamine resin (manufactured by Sumitomo Chemical Co., Ltd., Sumitekusu Resin M-3, solid content concentration 80% by weight) and urea resin (manufactured by Sumitomo Chemical Co., Ltd., Sumitekusu Resin M-3, solid content concentration 80% by weight) Tex Resin ULY (solid content concentration 20% by weight) was used in combination, and Sumitex Resin ACX was used as the hardening agent. In addition, as the phenolic resin powder, reactive granular phenolic resin (manufactured by Kanebo Co., Ltd., trade name Bell Pearl S, average particle size 15 μm), hardened novolac fiber powder (manufactured by Nippon Kynor Co., Ltd., KF02BT, fiber length 1mm) and resol resin (Gunei Chemical Industry Co., Ltd.)
Phenol resin powder (average particle size
20 μm) were used. First, heat and melt 600g of polyvinyl alcohol in the same manner as in Example 1, and then
3 Add 1.5Kg and Sumitekus Resin ULY1Kg and mix, then add a predetermined amount of phenol resin powder previously dispersed in water and water for adjusting the liquid volume to make a mixed liquid volume of 10Kg and mix thoroughly with stirring. did.
Table 2 shows the amount of phenolic resin powder in the mixed liquid. Add formalin (37% by weight) to this mixture.
600g and 300g of Sumitekus Resin ACX as a curing agent were added and a curing reaction was carried out in the same manner as in Example 1 to obtain a cylindrical porous polymer body. The physical properties of the porous polymer are shown in Table 2. This result shows that by using a reactive particulate phenolic resin, a good porous polymer material having fine continuous pores can be obtained.

[Table] Example 3 After heating and dissolving 700 g of polyvinyl alcohol with a degree of polymerization of 1000 and a degree of saponification of 99% in hot water, a water-soluble resol resin (manufactured by Sumitomo Durez Co., Ltd., Sumilite Resin PR961A, solid content concentration 64) was added to the solution. Weight%) 1.5Kg,
Reactive granular phenolic resin (manufactured by Kanebo Co., Ltd.,
700 g (trade name: Bell Pearl S, average particle size 20 μm) and 100 g of asbestos were added, the liquid volume was adjusted to 10 kg, and the mixture was thoroughly stirred and mixed. 700g of formalin (37% by weight) in the above mixture
After mixing 700g of sulfuric acid (50% by weight), 300mm
It was poured into a square mold, reacted for 24 hours in a hot water bath at 70℃, washed with a shower for 4 days after demolding, and dried at 80℃ to obtain a porous polymer material with fine continuous pores. . The continuous porosity of the porous polymer material was 72%, and the average pore diameter was 6 μm.

Claims (1)

[Claims] 1. A fine continuum characterized by adding a curing agent to a mixed liquid consisting of polyvinyl alcohol, a water-soluble thermosetting resin, and a reactive granular or powdery phenolic resin and curing the mixture by reaction. A method for producing a porous polymer material having pores. 2 The water-soluble thermosetting resin is a phenolic resin, a melamine resin, a urea resin, or two of them.
The method for producing a porous polymer according to claim 1, which is a mixture of more than one species. 3. The polymeric porous body according to claim 1 or 2, which is a spherical primary particle having an average particle size of 1 to 150 μm and a secondary aggregate thereof, of the reactive granular or powdery phenolic resin. Manufacturing method. 4 The composition of the mixed liquid is polyvinyl alcohol 0.5~
Claim 1: 15% by weight, 3 to 55% by weight of water-soluble thermoplastic resin in solid content, and 5 to 30% by weight of reactive granular or powdered phenolic resin. 2. A method for producing a porous polymer body according to any one of items 2 to 2.