JP2001259786A - Resin binder for shell mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a binder for shell molds which is excellent in thermal expansion characteristics and generates less soot while it is subjected to heat. SOLUTION: Phenol adducts of terpenes of 5 to 100 pts.wt. are mixed or kneaded with 100 pts.wt. of phenolic resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a resin binder for shell molds.

[0002]

2. Description of the Related Art A novolak-type or resol-type phenol resin obtained by reacting phenol and formaldehyde in an acidic or alkaline manner is generally used as a binder for resin-coated sand for casting (hereinafter abbreviated as RCS). However, a mold using this has a high rigidity and has a drawback of causing a crack during casting. For this reason, a method for preventing cracking by blending bisphenol A, bisphenol A purified residue, binsol, and the like with a phenol resin is generally used.

[0003]

However, in the method of blending the above-mentioned materials with a phenol resin, the curing speed is slow, soot is easily generated during heat exposure, a peculiar odor is generated during molding, and bisphenol A is generated. Had problems such as concern about environmental hormones. The present invention has been made in view of such circumstances, and provides a resin binder for a shell mold that does not have these disadvantages.

[0004]

Means for Solving the Problems The resin binder for a shell mold of the present invention comprises 5 to 100 parts by weight of an adduct of a terpene and phenol (hereinafter abbreviated as TPPh adduct) with respect to 100 parts by weight of a phenol resin. Are mixed or melted. The mold manufactured at 200 to 300 ° C. using the RCS coated with the binder of the present invention is:
Compared with the conventional mold, it was confirmed that soot was not generated at the time of heat exposure and cracks were also effectively prevented. Phenol, cresol, xylenol and the like are used as phenols of the phenol resin used in the present invention, and paraform and formalin and the like are used as aldehydes. As the phenolic resin used in the present invention,
Novolak-type phenolic resins, resol-type phenolic resins, and mixtures and mixtures thereof can be used. As the novolak-type phenol resin, a high-ortho-type novolak resin or an alkylphenol-modified novolak resin is used in addition to a commonly used phenol / formaldehyde novolak-type phenol resin.

The resole type phenol resin usable in the present invention includes a resole type phenol resin obtained by using a hydroxide of an alkali metal or an alkaline earth metal as a catalyst.
A resol-type phenol resin obtained by using ammonia or amines as a catalyst, and a resol-type phenol resin obtained by using a combined catalyst of ammonia or amines and an alkali metal or alkaline earth metal hydroxide can be used. It is also possible to produce RCS by using the novolak type phenolic resin binder and the resol type phenolic resin binder in combination. It is preferable to use a mixed melt of a resol-type phenol resin and a novolak-type phenol resin as the phenol resin because the mold strength is improved.

When a novolak type phenol resin and a resol type phenol resin are used in combination or mixed and mixed, the ratio of the two is not particularly limited, but 100 parts by weight of the resol type phenol resin and 60 parts by weight of the novolak type phenol resin. Parts by weight, preferably 30 to 50 parts by weight.
If the novolak type phenol resin is too large, the curing rate tends to be slow. As the TPPh adduct used in the present invention, a terpene diphenol and a terpene phenol copolymer have the same effect. As terpene diphenol and terpene phenol copolymer,
YP-90 and YP-90L (both are trade names manufactured by Yashara Chemical Co., Ltd.). If the amount is less than 5 parts by weight, the effect is small, and if it exceeds 100 parts by weight, the strength is unpreferably reduced. In the phenolic resin used in the present invention, as long as the essential effects of the present invention are not impaired, if necessary, curing accelerators such as aromatic organic acids commonly used in the art, lubricants and silane coupling. And the like. Salicylic acid, benzoic acid, or the like is used as the aromatic organic acid. The addition amount of the aromatic organic acid is preferably 0.05 to 5 parts by weight based on 100 parts by weight of the phenol resin. If the amount is less than 0.05 parts by weight, the effect is small,
If it exceeds 5 parts by weight, the RCS tends to be easily blocked.

[0007] A lubricant is preferably compounded in order to improve the mold strength and the blocking resistance. As the lubricant, ethylene bisstearic acid amide, ethylene bisoleic acid amide, methylene bisstearic acid amide, oxystearic acid amide, stearic acid amide, palmitic acid amide, oleic acid amide, methylol amide, calcium stearate, polyethylene wax, paraffin Wax, montan wax, carnauba wax and the like can be used. The amount of the lubricant to be added is 0.3 to 5 with respect to 100 parts by weight of the phenol resin.
It is desirable to use parts by weight. If the amount is less than 0.3 parts by weight, the effect is small, and if the amount is more than 5 parts by weight, the curing speed becomes slow.
Adhesion between sand grains tends to be impaired. The method for blending the lubricant is not particularly limited, but it is preferable to add and mix the lubricant at 150 ° C. or higher after the synthesis of the phenol resin. Further, the lubricant may be added at the time of producing the RCS by kneading the binder and the sand after the production of the resin.

[0008] The silane coupling agent is usually blended to increase the adhesion between the sand and the resin. The silane coupling agent that can be added to the resin binder for a shell mold of the present invention is not particularly limited, but an aminosilane coupling agent is preferable, and N-β (aminoethyl)-
γ-aminopropyltrimethoxysilane, N-β (aminoethyl) -γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, and the like are used, and the amount thereof is not particularly limited, but 100 parts by weight of a phenol resin. Is preferably used in an amount of 0.05 to 5 parts by weight. If the amount is less than 0.05 part by weight, the effect of improving the strength by the coupling agent is small.
CS tends to block easily. Hereinafter, the present invention will be further described based on examples.

[0009]

EXAMPLE 1 1340 g of phenol, 916 g of 37% formalin and 10 g of oxalic acid were added to a four-necked flask equipped with a stirrer, a reflux condenser and a thermometer, heated on an oil bath with stirring, and reacted at the reflux temperature. The reaction was performed until the liquid was emulsified. Thereafter, concentration was performed under reduced pressure, and when the softening point reached 85 ° C., the endpoint was determined. Then, a TPPh adduct (YP-Chemical: YP-
90) (1215 g) and 34 g of ethylene bisstearic acid amide as a lubricant were added and mixed with stirring for 1 hour to obtain 2570 g of a novolak type phenol resin binder. Example 2 The same operation as in Example 1 was carried out except that the amount of YP-90 in Example 1 was changed to 350 g, to obtain 1700 g of a novolak-type phenolic resin binder. Example 3 The same operation as in Example 1 was carried out except that the amount of YP-90 in Example 1 was changed to 108 g, to obtain 1458 g of a novolak type phenol resin binder. Example 4 As TPPh adduct instead of YP-90 in Example 1
(Yasuhara Chemical: YP-90L) The same operation as in Example 1 was carried out except that 1215 g was used. When the softening point reached 85 ° C., the end point was obtained. Then, 34 g of ethylenebisstearic acid amide was added and mixed. 2570 g of a resin binder was obtained. Example 5 The same operation as in Example 1 was carried out except that the amount of YP-90L in Example 4 was changed to 350 g, to obtain 1700 g of a novolak type phenol resin binder. Example 6 The same operation as in Example 1 was carried out except that the amount of YP-90L in Example 4 was changed to 108 g, to obtain 1458 g of a novolak-type phenol resin binder.

Comparative Example 1 To a four-necked flask equipped with a stirrer, a reflux condenser and a thermometer, 1340 g of phenol, 916 g of 37% formalin and 10 g of oxalic acid were added, and the mixture was heated on an oil bath with stirring, and the reaction mixture was heated at reflux temperature. The reaction was carried out until was emulsified. afterwards,
Concentration was performed under reduced pressure, and the end point was reached when the softening point reached 85 ° C. Then, 28 g of ethylene bisstearic acid amide was added and mixed, and the novolak type phenol resin binder 140
0 g was obtained. Comparative Example 2 With the formulation of Comparative Example 1, the same operation as in Comparative Example 1 was performed, and when the softening point reached 85 ° C., the end point was determined.
0 g and 34 g of ethylenebisstearic acid amide were added and mixed, and 1700 g of a novolak-type phenol resin binder was added.
I got

Production of Resin-Coated Sand (RCS) After kneading 230 g of each of the resins obtained in the above Examples and Comparative Examples in a speed mixer for 40 seconds, 10 kg of regenerated sand heated to 150 ° C., and then a 15% aqueous solution of hexamethylenetetramine 135 g was added and kneaded until the sand collapsed, 10 g of calcium stearate was further added and mixed for 20 seconds, and then discharged from the mixer to obtain RCS. Using the obtained RCS, the bending strength, the fusion point, the bend, the expansion characteristic at the time of heat exposure, and the appearance of soot at the time of measurement of the expansion characteristic were visually judged. Table 1 shows the results of the RCS characteristics.

[0012]

[Table 1]

[0013]

As is clear from the results shown in Table 1, according to the present invention, it is possible to obtain an RCS having excellent thermal expansion characteristics and less soot upon exposure to heat, and an excellent binder for a shell mold. It became possible to provide.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor: Ken Nanami 1500, Oji Ogawa, Shimodate City, Ibaraki Pref.Hitachi Chemical Industry Co., Ltd. CC05W CE00X ED056

Claims (2)

[Claims] 1. A resin binder for shell molds obtained by mixing or mixing 5 to 100 parts by weight of a phenol adduct of a terpene with 100 parts by weight of a phenol resin. 2. The resin binder for shell molding according to claim 1, wherein the phenol resin is a mixture of a novolak type phenol resin and a resol type phenol resin.