JPS6117846B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a solid resol type phenolic resin that is used as a binder for various purposes such as shell molds, brake linings, felts, grindstones, and molded plates using the beater addition method. The present invention relates to a method for producing a solid resol type phenolic resin that has been improved. Phenol resins are classified into novolac type phenolic resins and resol type phenolic resins. Novolak type phenolic resin (hereinafter referred to as novolak) generally contains 5 to 20% by weight of hexamethylenetetramine (hereinafter referred to as hexamine) as a curing agent.
It is used in combination with. This hexamine has excellent properties as a curing agent, so when used in novolak resins, it has the advantage of easily achieving rapid curing. However, on the other hand, nitrogen-containing gases such as ammonia and amines generated by the thermal decomposition of hexamine during heat curing can cause pinholes and voids in molded products for final use, leading to uneven density. or reduce strength. Furthermore, this nitrogen-containing gas has an extremely foul odor, causes rashes on workers, and has a significant negative impact on the human body. In order to improve these drawbacks of novolac resins, attempts have been made to utilize solid resol type phenolic resins (hereinafter referred to as solid resols) that harden by heating without the use of hexamine. A solid resol is generally a resin obtained by reacting 1 mol or more of an aldehyde with 1 mol of a phenol in the presence of an alkali catalyst. Resol resins reacted using divalent metal oxides or hydroxides as alkaline catalysts have a particularly fast curing speed because they contain methylene groups and methylol groups in the ortho position to the hydroxyl group of phenol. However, since this solid resol has a resin structure containing many hydrophilic methylol groups, its hygroscopicity is extremely high.For this reason, the resin is difficult to solidify and becomes a semi-solid resin, making it difficult to handle. On the other hand, when ammonia is used as an alkali catalyst, a hydrophobic solid resol can be obtained. This resin is generally called ammonia aresol.
Ammonia aresol is difficult to solidify when a small amount of catalyst is used, and tends to become solid when a large amount of catalyst is used. However, ammonia aresol basically has a drawback that the curing speed is slow because there are few methylol groups required for curing. However, the need for solid resols is increasing because they have the following features. Since it is a solid or powder, it is easy to handle. Productivity is improved because the base material and resin can be mixed efficiently using relatively simple equipment. Resol resins usually undergo a curing reaction little by little even at room temperature, so their storage period is limited, but solid resols have about twice the storage stability as liquid resols. An object of the present invention is to provide a solid resol that is less likely to solidify than ammonia resol and has faster curing properties. That is, the present application is a method for producing a solid resol obtained by reacting phenols and aldehydes in the presence of an aromatic amine and a divalent metal oxide or hydroxide. The present inventors have discovered that by using aromatic amines and divalent metal oxides or hydroxides in combination, rapid curing and caking properties are significantly improved compared to ammonia aresol. They discovered this and completed the present invention. Furthermore, in conventional ammonia aresol, the amount of nitrogen-containing gas generated due to ammonia as a catalyst is small compared to the amount of gas generated by decomposition of hexamine when hexamine is added to novolac, but it is not completely absent. . At work sites where conventional ammonia aresol is used in large quantities, there are still problems such as odor and deterioration of the work site. According to the present application, it has become clear that these problems can be solved all at once. The phenols used in this application include phenol,
Cresol, xylenol, paratertiary,
Butylphenol, bisphenol A, etc., but also resorcinol, catechol, hydroquinone,
Those containing urea, melamine, cashew nut shell oil, etc. can also be used. Further, as the aldehyde, an aldehyde substance selected from formalin, paraformaldehyde, trioxane, etc. is used. The amount of aldehydes to be used is generally desirably 1 to 3 moles per mole of phenols. If the molar ratio of aldehydes is greater than 3, the amount of free aldehydes in the resulting resin will increase, which will generate gas with a pungent smell during heat curing and cause gas defects to occur in the final molded product. Become. Moreover, when the molar ratio of aldehydes is less than 1, the curing of the obtained resin becomes slow, making it difficult to put it into practical use. Aromatic amines used in this application include aniline, alkyl-substituted anilines such as toluidine, chloroaniline, naphthylamine, phenylenediamine,
These are compounds in which at least one aromatic nucleus is substituted with an amino group, such as benzenediamine, alkyl-substituted benzenediamine, and aminophenol.
Note that the recommended aromatic amine is aniline.
This aromatic amine exerts a catalytic action on phenols and aldehydes, and also reacts with aldehydes to co-condense them into the resin. The amount of aromatic amine used is preferably 0.03 to 0.5 mol per 1 mol of phenols. If the amount of aromatic amine is less than 0.03 mole per mole of phenol, the resulting resin tends to solidify. Moreover, if it exceeds 0.5 mol, the curing of the produced resin will be delayed and the cost will increase.
The aromatic amine can be added before or during the reaction between the phenols and the aldehydes. The oxides or hydroxides of divalent metals used in the present invention include hydroxides or oxides of alkaline earth metals such as magnesium, calcium, and barium, and oxides or hydroxides of zinc, which are usually used in the production of resol resins. The catalyst used. One or more of these may be used. The amount of divalent metal oxide or hydroxide used is 0.001 per mole of phenols.
~0.2 mol is desirable. If the amount of alkali catalyst is less than 0.001 mol per mol of phenol, the curing speed of the obtained resin will be slow, and if it exceeds 0.2 mol, the caking resistance of the obtained resin will tend to deteriorate. . A lubricant such as a novolac resin or stearamide may also be added to the solid resol of the present invention during resin production. Further, the solid resol alone or the solid resol blended with a novolak resin can be pulverized, and if necessary, a lubricant such as calcium stearate or a filler such as calcium carbonate may be blended for use in various applications. Next, the present invention will be further explained with reference to Examples, but the present invention is not limited by these. Further, "parts" and "%" described in each example and comparative example indicate "parts by weight" and "% by weight." Example 1 940 parts of phenol, 1461 parts of 37% formalin, 20 parts of magnesium hydroxide and 250 parts of aniline were charged into a reaction vessel equipped with a stirrer and a reflux condenser, and heated to 70°C.
and kept at this temperature for 90 minutes. Then the degree of decompression
Dehydration and release of phenol were performed by heating at 650 m/mHg. When the melting point of the resin reaches 85℃, the reaction vessel is discharged and rapidly cooled, reducing the water content to 1.3℃.
%, free phenol 5.0% solid resol was obtained. Example 2 940 parts of phenol, 1299 parts of 37% formalin and 30 parts of zinc hydroxide were charged into a reaction vessel equipped with a stirrer and a reflux condenser, and after raising the temperature to 90°C, 180 parts of aniline was added.
portion was added dropwise over 20 minutes. temperature
The reaction was continued for an additional 30 minutes while maintaining the temperature at 90°C. Next, the mixture was heated at a reduced pressure of 650 m/mHg to perform dehydration and elimination of phenol. When the melting point of the resin reached 80°C, the reaction vessel was discharged and rapidly cooled to obtain a solid resol containing 1.0% water and 3.9% free phenol. Comparative Example 940 parts of phenol, 1299 parts of 37% formalin, and 60 parts of 25% aqueous ammonia were charged into a reaction vessel equipped with a stirrer and a reflux condenser, and reacted at 90°C for 45 minutes. Then, the mixture was heated at a reduced pressure of 650 m/mHg to perform dehydration and elimination of phenol. The melting point of the resin is 80
When the temperature reached ℃, the reaction vessel was discharged and rapidly cooled to obtain a solid resol containing 1.3% water and 4.2% free phenol. Table 1 and FIG. 1 show the results of the caking resistance test and hardenability test of the solid resols obtained in Examples 1 and 2 and Comparative Example.

[Table] The test method is as follows. (1) Caking resistance test method 100g of resin crushed into 60 mesh or less
Place in a 0.07mm polyethylene bag and tie tightly with a rubber band. After applying a load of 0.8 kg and leaving it in an atmosphere of 30°C and 70% RH for 48 hours, sieve the solidified matter with a 40 mesh sieve and measure its weight. Consolidation rate (%) = Consolidation weight (g) / 100 (g) ×
100 (2) Curing test method (2.1) Gelation time Place the resin on a hot plate at 150°C, stir with a spatula, and measure the gelation time. (2.2) Curing properties using a Cyulastometer When using a JSR type Cyulastometer, the upper and lower molds were heated to 150℃, the resin was put into the molds, and the lower mold was vibrated at an angle of ±0.7℃. , the change in stress occurring in the upper mold is measured over time. Table 1 and FIG. 1 show that Examples 1 and 2 have a lower solidification rate than the comparative example, and the gelation time is short and the stress is high, indicating that the curing property is fast.

[Brief explanation of the drawing]

FIG. 1 shows the results of a curing test of the resin using a culastometer. B is Example 1, C is Example 2, and D is Comparative Example.

Claims (1)

[Scope of Claims] 1. A method for producing a solid resol type phenolic resin obtained by reacting phenols and aldehydes in the presence of an aromatic amine and a divalent metal oxide or hydroxide. 2 Aromatic amine per mole of phenols,
The method for producing a solid resol type phenolic resin according to claim 1, wherein the amount of the divalent metal oxide or hydroxide is 0.001 to 0.2 mole per mole of the phenol. 3. The method for producing a solid resol type phenolic resin according to claim 1 or 2, wherein the aromatic amine is aniline. 4. The method for producing a solid resol type phenolic resin according to claim 1 or 2, wherein the divalent metal is a metal selected from magnesium, calcium, barium, and zinc.