JPH0651824B2 - 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] Conventionally, a formaldehyde source such as hexamethylenetetramine, paraformaldehyde or trioxane has been used as a curing agent for a novolac type phenolic resin (hereinafter referred to as novolac resin). 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.
No. 20589, Japanese Examined Patent Publication No. 60-31340), a method of adding 0.5 to 5% by weight of an aliphatic saturated dicarboxylic acid to a novolac resin (Japanese Patent Laid-Open No. 53-124118).
No.), and a method of adding about 1 to about 5% by weight of a urea compound such as urea, ethylene urea, and furopyrene urea to a novolak 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 urea compound is added, the effect of shortening the curing time is small, and generally 2 to 3% by weight based on the novolak 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 desired object can be achieved by combining a novolak resin with a specific organic acid and an amino compound, and have completed the present invention.

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, satylic acid, adipic acid and succinic acid. And a phenolic resin binder comprising an organic acid selected from phthalic acid and an amino compound selected from aminophenol, urea, nitroaniline and melamine.

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). Then, vacuum concentration dehydration is performed up to about 150 to 190 ° C. to obtain a novolac resin. An organic acid and an amino compound are dissolved in this novolak resin and, if necessary, processed into powder or granules to obtain a fast-curing phenol resin binder.

The addition amount of the organic acid and the amino compound is not specifically limited depending on the conditions used, but is usually 0.1 to 3.0 parts by weight, preferably 0.2 parts by weight with respect to 100 parts by weight of the phenol resin.
~ 1.5 parts by weight is optimal.

In addition, the method of adding the organic acid and the amino compound is most preferably uniformly dissolved or dispersed in the novolak resin at the time of resin synthesis as described above, but is not limited to this and is added at the time of pulverization or 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 amino compound uniformly dissolved or dispersed in a novolac resin. Organic acids such as benzoic acid and salicylic acid accelerate the decomposition of hexa, which is a curing agent for novolac resins, and amino compounds such as aminophenol increase the number of cross-linking reactive groups when the novolac resin cures. The curing time of the novolac resin is greatly reduced with a small addition amount.

[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 part by weight of oxalic acid was further added, and the mixture was refluxed. Allow 90 minutes for condensation reaction. Then, dehydration concentration is performed up to 170 ° C. under reduced pressure of −60 to −70 cmHg to obtain 98 parts by weight of novolak resin. The organic acid and amino compound shown in Table 1 were dissolved in 100 parts by weight of this novolak resin to obtain a phenol resin binder.

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

The results are also shown in Table 1. In addition, as a legend of the measurement result “odor”, ○: small irritating odor Δ: medium irritating odor, ×: large irritating odor was adopted. The gel time is 100 for phenol resin.
By mixing 15 parts by weight of hexa with parts by weight, JIS K-
According to 6910, it was measured on a hot plate at 150 ° C. The softening point was measured according to JIS K-6910.

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

[Application Example 1] Using the phenol resin binders of Examples 2, 5, and 7 and Comparative Examples 2 and 7, resin-coated sand particles for shell mold (hereinafter referred to as RCS) were obtained by the following method, and their characteristics 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 phenol resin binder is added at 160 ° C. and kneaded for 30 seconds, and then an aqueous solution in which 24 g of hexa is dissolved in 210 g 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 with 100 parts of the phenol resin binders of Examples 1, 4, 6 and Comparative Examples 4 and 5 while coarsely pulverizing, 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. The results are shown in Table 3.

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 oven at 40 ° C and after 72 hours 2
It was taken out on a 4-mesh sieve, and 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.

EFFECTS OF THE INVENTION The phenol resin binder of the present invention is a phenol resin binder having a short gel time and a high curing rate, as seen in Examples. 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 RCS blocking or defective sand clogging, and further has a warm bending strength. Since it is expensive, there is an advantage that the productivity of mold making 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 amino compound selected from aminophenols, urea, nitroaniline and melamine.