JPH0651823B2 - Phenolic resin binder - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a fast-curing novolac-type phenol resin binder, and more particularly, to molds, felts, grindstones, silica sand, fibers, and abrasives in friction materials. The present invention relates to a fast-curing novolac-type phenol resin binder for binding organic or inorganic base materials such as particles.

[Prior Art] As a curing agent for a conventional novolac type phenolic resin (hereinafter referred to as a novolac resin), hexamethyltetramine,
Formaldehyde sources such as paraformaldehyde and trioxane are used, and generally hexamethylenetetramine (hereinafter referred to as hexa) is widely used.

The composition obtained by blending hexa with novolac resin has a short curing time and is sufficiently satisfactory, but it is strongly desired in the art to further shorten the curing time in order to further improve the workability. Various attempts have heretofore been made to shorten the curing time and obtain a fast-curing novolac resin binder.

For example, in the reaction of a novolac resin and hexa, a fast-curing novolac resin bond utilizing the fact that a so-called high ortho novolac resin has a high curing rate, which has a large number of methylene bridges bonded to the ortho-ortho position with respect to a phenolic hydroxyl group. Method for obtaining agent (Japanese Patent Publication No.
JP-A-54-127997 and JP-A-59-804.
No. 18) is known.

As another method, a method of adding an aromatic carboxylic acid such as salicylic acid to novolac resin and hexa (Japanese Patent Publication No.
-20589, JP-A-60-31340), a method of adding 0.5 to 5% by weight of an aliphatic saturated carboxylic acid to a novolac resin (JP-A-53-124118),
Also known is a method of adding about 1 to about 5% by weight of a urea compound such as urea, ethylene urea and propylene urea to the novolac resin (Japanese Patent Publication No. 53-26562).

[Problems to be Solved by the Invention] However, although the conventionally known method of shortening the curing time can shorten the curing time of the novolak resin, it is possible to avoid other problems from occurring. Can not.

For example, in the case of a high ortho novolac resin, it is difficult to control the synthesis method, there is a risk of gelation, or it is difficult to obtain a stable quality novolac resin, and the yield is poor and there is a problem in terms of cost. On the other hand, when a carboxylic acid or a urea compound is added, the shortening of the curing time causes little curing, and generally 2 to 3% by weight relative to the novolac resin.
Is required. Therefore, the softening point of the novolac resin is greatly reduced, and in the case of powdered novolac resin used for felts, grindstones, friction materials, etc., it causes resin block, causing product defects, and eventually There is a problem that it cannot be used. In addition, when used as sand particles for shell mold, there arises a problem that not only the resin but also the resin-coated sand particles cause a block, or the mold becomes defective in clogging due to a decrease in fluidity of the sand particles. Further, in the case of carboxylic acid, not only lowering the softening point of the resin,
There is also a problem that a pungent odor is generated and the working environment is deteriorated.

[Means for Solving the Problems] The present inventor has developed a novolac resin binder in which the curing time is significantly shortened as compared with the conventional fast-curing novolac resin binder and the above-mentioned problems do not occur. I have been diligently conducting research. As a result, they have found that the intended purpose can be achieved by combining a novolak resin with a specific organic acid and an ammonium salt, and the present invention has been completed.

That is, the present invention relates to a novolac type phenol resin obtained by condensation reaction of 0.50 to 0.95 mol of formaldehyde with 1 mol of phenol under an acidic catalyst, benzoic acid, salicylic acid, adipic acid and succinic acid. And a phenolic resin binder comprising an organic acid selected from phthalic acid and an ammonium salt selected from ammonium nitrate, ammonium sulfate, ammonium chloride and ammonium benzoate. The phenols used as a raw material of the novolac type phenol resin used in the present invention include phenol, cresol, xylenol, dioxybenzene, bisphenol A and the like, alone or in a mixture.

As formaldehyde, formalin, paraformaldehyde, etc. are used.

As the acidic catalyst, an inorganic acid such as hydrochloric acid, sulfuric acid or phosphoric acid or an organic acid such as acetic acid, oxalic acid or paratoluenesulfonic acid may be used alone or in a mixture.

Next, the phenol resin binder of the present invention is produced, for example, as follows.

0.5% of 37% formalin to 1 mol of phenol
About 0.95 mol is subjected to a condensation reaction under reflux for a predetermined time under an acidic catalyst (hydrochloric acid or oxalic acid is preferable). After that, concentrate and dehydrate under reduced pressure up to about 150 to 190 ° C,
Obtain novolak resin. An organic acid and an ammonium salt are dissolved in this novolak resin and, if necessary, processed into powder or granules to obtain a fast-curing phenol resin binder.

The amount of the organic acid and ammonium salt added is not generally limited depending on the conditions used, but usually the phenol resin 100
0.1 to 3.0 parts by weight, preferably 0.
The optimum range is 2 to 1.5 parts by weight. In addition, the method of adding the organic acid and the ammonium salt is most preferably uniformly dissolved or dispersed in the novolak resin during the resin synthesis as described above, but the method is not limited to this and is added during pulverization or during use. You can also

In addition to the above, the phenol resin binder of the present invention may include a lubricant such as stearic acid, a stearate salt, paraffin, polyethylene wax, and ethylenebisstearic acid amide, a silane coupling agent such as aminosilane or epoxysilane, if necessary. Can be included.

[Function] The phenolic resin binder of the present invention contains an organic acid and an ammonium salt uniformly dissolved or dispersed in a novolac resin. Organic acids such as benzoic acid and salicylic acid promote the decomposition of hexa, which is a curing agent for novolac resins, and ammonium salts such as ammonium sulfate also promote the decomposition of hexa, which synergistically acts. Curing time of novolak resin is greatly shortened with a small amount of addition.

[Examples] Examples of the present invention will be shown below, but the present invention is not limited thereto.

[Examples 1 to 7 and Comparative Examples 1 to 7] 100 parts by weight of phenol and 59 parts by weight of 37% formalin were charged into a reaction can equipped with a thermometer and a condenser, and 0.5 parts by weight of oxalic acid was added to the reaction container to add oxalic acid. 0.5 part by weight is added, and a condensation reaction is performed for 90 minutes under reflux. Then -60 ~
Perform dehydration concentration to 170 ° C under reduced pressure of -70 cmHg to 98
One part by weight of novolak resin is obtained. This novolac resin 1
The phenolic resin binder was obtained by dissolving the organic acid and ammonium salt shown in Table 1 in 100 parts by weight.

These phenolic resin binders were finely ground and the gel time and softening point were measured.

The results are also shown in Table 1. The gel time was obtained by mixing 15 parts by weight of hexa with 100 parts by weight of phenol resin,
The measurement was performed on a hot plate at 150 ° C. according to JIS K6910. The softening point was measured according to JIS K-6910.

Next, an application example of the present invention will be shown.

[Application Example 1] Resin-coated sand grains for shell mode (hereinafter referred to as RCS) were obtained by the following method using the phenol resin binders of Examples 1, 4, 6 and Comparative Examples 2, 6 and their properties were measured. The results are shown in Table 2.

RCS is a speed mixer (Enshu Iron Works, NSC-2
8 kg of fuuka sand heated to 160 ° C is added to the mold), the above-mentioned phenol resin binder is added to 160 ° C and kneaded for 30 seconds, and then an aqueous solution in which 24g of hexa is dissolved in 120g of water is added, and stirred until the sand grains collapse. After that, 8 g of calcium stearate was added, the mixture was further stirred for 20 seconds, and sand was discharged to obtain RCS.

(Application Example 2) 15 parts of hexa and 0.5 part of calcium stearate were mixed while coarsely pulverizing with 100 parts of the phenol resin binders of Examples 2, 5 and 7 and Comparative Examples 4 and 7, and further finely mixed. It was pulverized to obtain a binder for felt as a fine powder having an average particle size of 8 μm.

25 parts of the felt binder obtained above and 100 cotton fibers
The parts are mixed with an anti-fluffing machine to make a fleece of 260 × 240 × 80 (mm) and a weight of 45 to 50 g, which is heated and pressed to a thickness of 10 mm at 200 ° C. for 5 minutes to have a density of 0.06 to 0.0.
7 g / cm ³ felt was molded. Immediately, from the felt obtained, three test pieces of 50 × 150 × 10 (mm) were cut out, each test piece was placed on a beam with a fulcrum distance of 10 cm, a load of 100 g was applied to the center, and after 10 seconds. The amount of deflection was measured. The smaller the amount of deflection, the better the curability. Also, after the same test piece as described above was cooled to room temperature, the tensile strength was measured with a Tensilon type tensile tester.

Regarding the blocking property of the binder for felt, 25 g of the binder for felt was put into a cylindrical container having a diameter of 50 mm and a load of 1 kg was applied. Put this in an orb at 40 ° C and after 72 hours 24
It was taken out on the sieve of the mesh, the weight of the binder for felt remaining on the sieve was measured, and the blocking rate was expressed in percentage.
The results are shown in Table 3.

[Effect of the Invention] As seen in the examples, the phenol resin binder of the present invention is a phenol resin binder having a short gel time and a high curing rate. Furthermore, the softening point of the phenol resin binder is small and the blockage of the phenol resin binder is less likely to occur.

Further, as is clear from the results of application examples, when applied to RCS, the phenol resin binder of the present invention has a high fusion point and is unlikely to cause blocking of RCS or defective sand clogging, and further has a warm bending strength. Since it is expensive, there is an advantage that the productivity of the casting difficult mold is improved.

Further, when it is applied to felt, it can be seen that the curability is good because the block rate is small and the amount of deflection is small.

As described above, the phenol resin binder of the present invention is excellent in that the curing time is significantly shortened as compared with the conventional ones, the softening point is not significantly lowered, and there is no block.

Claims (1)

[Claims] 1. A novolac type phenol resin obtained by condensation reaction of 0.50 to 0.95 mol of formaldehyde with 1 mol of phenol under an acidic catalyst, benzoic acid, salicylic acid, adipic acid, and amber. A phenolic resin binder comprising an organic acid selected from acids and phthalic acids and an ammonium salt selected from ammonium nitrate, ammonium sulfate, ammonium chloride and ammonium benzoate.