JPH0757824B2 - Method for producing phenolic resin porous body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is excellent in chemical resistance and abrasion resistance, has a low porosity and has fine continuous pores, and is suitable for applications such as abrasives and filter media. The present invention relates to a method for producing a phenolic resin porous body.

(Prior Art) Conventionally, as a method for producing a phenolic resin porous body having a low porosity and fine continuous pores, a liquid phenolic resin, a reactive granular or powdery phenolic resin,
Also known is a method (Japanese Patent Publication No. 63-32818) in which a curing catalyst is added to a mixture containing starch or polyvinyl alcohol as a pore-forming material to effect a reaction curing. Phenolic resin porous body obtained by this method,
It has fine and uniform rope-like continuous pores, is more rigid and has high strength, but has the drawbacks of low abrasion resistance and softening and swelling in alcohols. For this reason, when it is used as a polishing material, a filtering material, etc., only those having poor durability and alcohol resistance can be obtained.

(Problems to be Solved by the Invention) As a result of intensive studies conducted by the present inventors in view of the above problems, a phenolic resin having excellent chemical resistance and abrasion resistance by mixing a specific melamine resin The present invention has been completed to find out that a porous body can be obtained, and its purpose is to have excellent wear resistance and chemical resistance (particularly alcohol resistance), low porosity and fine continuous Another object of the present invention is to provide a method for producing a phenolic resin porous body having pores.

(Means for Solving the Problems) The above-mentioned object is characterized by adding a curing catalyst to a mixture containing a resol-type phenol resin, a melamine resin acid colloid, a pore-forming material, polyvinyl alcohol and a cross-linking agent thereof, and carrying out reaction curing. And a method for producing a phenolic resin porous body.

The resol type phenolic resin (hereinafter referred to as "resole resin") used in the present invention is preferably water-soluble.

Resole resin is an initial product produced by reacting phenols with aldehydes in the presence of a basic catalyst, and generally, relative to 1 mol of phenol,
A water-soluble resol resin can be obtained by keeping an initial condensate obtained by reacting 1.5 to 3.5 mol of aldehydes in the presence of a slight excess of an alkali catalyst in a stable water-soluble state.

Most commonly, the phenols used to make the resole resin include phenol and cresol. However, other phenols can also be used, for example phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,5-xylenol, 2,4-xylenol. , 2,6-xylenol, 3,4-xylenol, 3,5-xylenol, o-ethylphenol, m-ethylphenol, p-ethylphenol, p-phenylphenol, p-te
Examples include rt-butylphenol, p-tert-aminophenol, bisphenol A, resorcinol and mixtures of these phenols.

Formaldehyde is the most common aldehyde used for polycondensation with the phenols. However, paraaldehyde, hexamethylenetetramine, furfural and monoaldehydes and cyaldehydes such as glutaraldehyde, adiboaldehyde and glyoxal may also be used.

As the basic catalyst used in the resol resin synthesis reaction, caustic alkali, alkali carbonate, barium hydroxide, calcium hydroxide, ammonia, quaternary ammonium compound,
Known amines and the like may be used, and caustic soda or ammonia is most commonly used.

The melamine resin acid colloid used in the present invention is an initial condensate of a melamine resin having an average degree of polymerization of usually about 20, and melamine resin (methylolmelamine) is mixed with an acid such as acetic acid, lactic acid or hydrochloric acid and aged. It is a colloid having a hydrophilic positive charge that is generated.

The melamine resin acid colloid is produced, for example, as follows. That is, melamine resin (methylol melamine)
Is dissolved in warm water, the above-mentioned acids are added while stirring the obtained resin liquid, and water is further added. Next, this mixed solution may be put in a container, sealed, and aged while maintaining the temperature at about 30 ° C. to obtain a colloidal state. The acids used here also have an effect as a curing catalyst described later.

In the present invention, examples of the pore-forming material used for imparting continuous pores include starch, processed starch and water-soluble polymers. The processed starch is one in which starch is once gelatinized, then dried, pulverized, and classified as necessary. The amount of the pore forming material used may be appropriately selected according to the desired porosity, but is preferably 0.5 to 5 W / V%
It is a degree. If the amount of the pore-forming material is too small, the number of independent pores increases, and it is difficult to wash and remove the pore-forming material after the reaction. On the other hand, if the amount of the pore-forming material is too large, the kneading becomes difficult.

Polyvinyl alcohol used in the present invention is not particularly limited, for example, average polymerization degree 300 ~ 3000, saponification degree
70 mol% or more is mentioned.

Examples of the crosslinking agent for polyvinyl alcohol include aliphatic aldehydes such as formaldehyde and acetaldehyde, and aromatic aldehydes such as benzaldehyde.

In order to obtain a phenol resin porous body having fine continuous pores by using the above-mentioned resole resin, melamine resin acid colloid, pore-forming material, polyvinyl alcohol and its cross-linking agent, for example, the following may be carried out. That is, a resole resin and polyvinyl alcohol are mixed, and an aqueous dispersion or aqueous solution of a pore-forming agent is added to the mixture and mixed uniformly. A cross-linking agent and a melamine resin acid colloid are added to and mixed with this, and subsequently a curing catalyst is added and uniformly stirred and mixed to form a reaction stock solution, which is poured into a mold having a predetermined shape and reacted by heating. The curing catalyst may be appropriately selected from commonly used inorganic acids such as sulfuric acid and hydrochloric acid, organic acids such as formic acid, acetic acid, oxalic acid, lactic acid, citric acid, and paratoluenesulfonic acid.
Sulfuric acid and hydrochloric acid are preferably used. The addition amount of the curing catalyst may be appropriately selected according to its type. In carrying out the curing reaction, the heating means may be appropriately selected from various methods such as a hot water bath, hot air, steam, electric heating, and high frequency heating.

In the above-mentioned method, the amount of the melamine resin acid colloid to be added to the reaction stock solution is preferably 1 W / V% or more in the case of a solution of about 8 to 10% of the active ingredient produced by a usual method.

After completion of the reaction, the molded product may be taken out of the mold, washed with water or the like to wash away the pore-forming agent, the curing catalyst, etc., dehydrated and dried.

In the present invention, when an initial condensate of a melamine resin (methylolmelamine) is used in place of the melamine resin acid colloid, the mixed liquid is difficult to disperse, and the pore diameter varies greatly, failing to achieve the object.

(Effects of the Invention) The phenolic resin porous body obtained by the above method is excellent in abrasion resistance, has a low porosity and has uniform reticulated fine continuous pores, and is rigid and has high strength, and is alcohol resistant. Has excellent chemical resistance such as properties.

The phenolic resin porous material according to the present invention is used in various applications by taking advantage of such characteristics, but particularly when used as an abrasive such as a grindstone or a filter of a solid-liquid separation device, it has excellent durability. Excellent and suitable.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. In addition,
Before that, various performance evaluation methods in this specification will be described.

<Abrasion resistance> JIS L0849 (Test method for dyeing fastness to friction) was performed, and a Gakushin-type tester was used as a test device. The other test conditions are as follows, and the cutting wear amount of the test piece was evaluated when the friction number was 5000 times.

Masatsuko ... sandpaper # 60 Masatsuko load ... Masatsuko (200 g) + weight weight (300 g) Total 500g contact area ... 4 cm ² friction velocity of the contact area Masatsuko ... 1 cm ² specimens ... 5 to 6 m / min < Bending strength> JIS-K6911.5.17.3 (General test method for thermosetting plastics)
It was carried out according to. The test pieces used were 200 mm long, 20 mm wide, and 3 mm thick. The bending method when a load of 1000 g was applied to the center of the sample was visually evaluated relatively.

○ Slight bending amount △ Slight bending amount <Alcohol swelling ratio> After immersing in a 30% methyl alcohol aqueous solution for 20 days, the swelling ratio was measured.

<Alkaline swelling rate> After immersing in a sodium hydroxide aqueous solution of pH 12 for 20 days,
The swelling rate was measured.

<Durability of filter media> As a phenolic porous material, outer diameter 304 mm, inner diameter 240 mm, length 30
It was used as a filter medium having a cylindrical shape of 0 mm, which was disclosed in JP-A-61-249515.
It was attached to a solid-liquid separator having a structure as shown in FIG. A liquid obtained by dispersing fine powder in a 25% methanol aqueous solution at 60 ° C. was used as a suspension, and the solid content was scraped off while the surface of the filter medium was gradually ground by a scraping device.

The solid-liquid separation as described above was continuously performed, and the time until the filter medium became unusable was measured to determine the durability of the filter medium.

Example Water-soluble resol resin (trade name: PR961A, Sumitomo Durez Co., Ltd., solid content 64%) and polyvinyl alcohol (trade name: PVA
117, manufactured by Kuraray Co., Ltd.) and the solid content ratio was 3.5 / 1, and the total weight of the solid content was a predetermined amount of 30 W / V% to prepare an aqueous solution. Next, steamed potato starch of 5 W / V% was added to this aqueous solution and thoroughly kneaded, followed by 37% as a cross-linking agent.
An aqueous formaldehyde solution was added at 8 W / V%, and a melamic acid colloidal solution produced by the method described later was added at 3 W / V% and kneaded. Subsequently, 30% sulfuric acid as a curing catalyst was added at 7 W / V%, and water was added to a predetermined amount to uniformly knead to obtain a reaction stock solution.

The obtained reaction stock solution was put in a vinyl chloride mold and allowed to react at 50 ° C for 20 hours. The obtained reaction product was taken out of the mold and showered for 3 days to remove starch and unreacted materials, and then dried. A phenol resin porous body was obtained. Various properties of the obtained porous body are shown in Table 1.

<Melamine resin acid colloid production method> Melamine resin Sumitex Resin M-3 (Sumitomo Chemical Co., Ltd., active ingredient 80%) 1000 ml was dissolved in 4500 ml water, and 35% hydrochloric acid 140 ml was added while stirring the resin solution. , And then water was added to make the volume constant at 6000 ml. The solution was sealed and aged at 30 ° C. for 5 hours to give a colloidal state, and then 3000 ml of water was added to obtain a melamine resin acid colloidal solution.

Comparative Example 1 Melamine resin used in Examples Instead of acid colloid, melamine resin before acid colloid Sumitex Resin
A phenolic resin porous body was obtained in the same manner as in Example, except that the M-3 solution was kneaded so that the melamine resin content was the same as in Example. It should be noted that the resin mixed liquid in the manufacturing process was more difficult to disperse than that of the example, and some parts were not uniformly dispersed.

Various properties of the obtained porous body are as shown in Table 1.

Comparative Example 2 A phenolic resin porous body was obtained in the same manner as in Example except that the melamic acid colloid solution added in Example was not added.

Various properties of the obtained porous body are shown in Table 1.

[Brief description of drawings]

FIG. 1 is an explanatory view of a solid-liquid separation device used for determining the durability of a filter medium. 1 ... Filter material (phenolic resin porous body) 2 ... Suspension, 3 ... Suction pump 4 ... Scraping device, 5 ... Suspension tank 6 ... Motor, 7 ... Side plate 8 ... Deceleration mechanism

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display area C08L 61/28 LNL // C08G 16/00 NDF

Claims (1)

[Claims] 1. A method for producing a phenolic resin porous body characterized by adding a curing catalyst to a mixture containing a resol-type phenolic resin, a melamine resin acid colloid, a pore-forming material, polyvinyl alcohol and a crosslinking agent thereof to effect reaction curing. Method.