JP2001259785A - 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: The copolycondensation of adducts of phenol with phenols and terpenes and aldehydes is effected. The phenol adducts of the terpenes of 5 to 90 pts.wt. are mixed with phenols of 100 pts.wt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a binder for shell molds.

[0002]

2. Description of the Related Art As a binder used in resin-coated sand for casting (hereinafter abbreviated as RCS), a resin obtained by reacting phenols and formaldehydes in an acidic or alkaline manner is usually used. However, molds using them have high rigidity and have the disadvantage of causing cracks during casting. For this reason, a method of 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 has as its object to provide a binder for a shell mold which has excellent thermal expansion characteristics and generates less soot when exposed to heat.

[0004]

That is, the present invention provides a phenol adduct of phenols and terpenes (hereinafter referred to as TPP).
h adduct) and an aldehyde.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Phenol, cresol, xylenol and the like are used as phenols used in the present invention, and paraform and formalin are used as aldehydes. When synthesizing a binder for a shell mold using these raw materials and the above-mentioned TPPh adduct, a commonly used method for synthesizing a phenol resin is used. That is, the novolak type phenol resin is
Formaldehyde 0.5 to 1 mole of phenols
The synthesis is carried out using 0.9 mol of an acidic catalyst such as oxalate, acid sulfuric acid or a combination catalyst thereof. The resole type phenol resin is composed of 1.1 to 2.0 moles of formaldehyde and 1 mole of phenols, ammonia, sodium hydroxide,
The synthesis is carried out using an alkaline catalyst such as trimethylamine, hexamine or a combination catalyst thereof. The high ortho-type novolak resin is synthesized using 0.5 to 0.8 mol of formaldehyde and 1 mol of phenols and a divalent metal salt catalyst such as zinc acetate, manganese acetate, cobalt acetate or a combination thereof. In the present invention, these phenol resins can be used alone or in combination. It is also possible to produce RCS by using the novolak type phenol resin and the resol type phenol resin in combination. In particular, it is preferable to use a mixed melt of a resol type phenol resin and a novolak type phenol resin because the mold strength is improved. In this case, novolak-type phenolic resin is used in an amount of 60 parts by weight or less, preferably 30 to 50 parts by weight, based on 100 parts by weight of the resol-type phenolic resin.
Add during manufacturing. If the amount of the novolak-type phenol resin is too large, the curing speed becomes slow. The TPPh adduct is added and co-condensed before or during the reaction between the phenol and the aldehyde. As the TPPh adduct used in the present invention, a terpene diphenol and a terpene phenol copolymer have the same effect. Specifically, YP-90, YP-90L, YP-90
LL (all are trade names manufactured by Yashara Chemical Co., Ltd.). The compounding amount is 5 to 90 parts by weight of a phenol adduct of a terpene per 100 parts by weight of the phenol. If the amount is less than 5 parts by weight, the effect is small, and if it exceeds 90 parts by weight, the strength tends to decrease.

[0006] The TPPh-modified phenolic resin may contain a curing accelerator such as an aromatic organic acid commonly used in the art, if necessary, as long as the essential effects of the present invention are not impaired.
A lubricant and a silane coupling agent may be blended. 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 modified phenol resin. If the amount is less than 0.05 part by weight, the effect is small, and if the amount is more than 5 parts by weight, blocking tends to occur. The lubricant is
It is preferable to mix them in order to improve the strength of the mold and to improve 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 added was 100 modified phenolic resin.
It is desirable to use 0.3 to 5 parts by weight with respect to parts by weight. When the amount is less than 0.3 part by weight, the effect is small, and when the amount is more than 5 parts by weight, the curing speed becomes slow, and the adhesive force between sand particles tends to be inhibited. The method of blending the lubricant is not particularly limited, but it is preferable to add the lubricant at 150 ° C. or higher after the synthesis of the modified 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.

[0007] 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. It is desirable to use 0.05 to 5 parts by weight based on parts. If the amount is less than 0.05 part by weight, the effect of improving the strength by the coupling agent is small, and if the amount is more than 5 parts by weight, the phenol resin has a risk of blocking, which is not preferable. Hereinafter, the present invention will be further described based on examples.

[0008]

EXAMPLES Synthesis of Binder Resin Example 1 In a four-necked flask equipped with a stirrer, a reflux condenser and a thermometer, 1340 g of phenol, 1194 g of 37% formalin,
TPPh adduct (YP-90L, manufactured by Yashara Chemical) 10
After adding 00 and 10 g of oxalic acid, the mixture was heated on an oil bath with stirring and reacted at reflux temperature until the reaction solution was emulsified. Thereafter, concentration was carried out under reduced pressure, and the end point was reached when the softening point reached 85 ° C. Then, 47 g of ethylenebisstearic acid amide was added and mixed as a lubricant to obtain 2350 g of a novolak-type phenol resin composition. Example 2 The same operation as in Example 1 was performed except that 1000 g (YP-90LL, manufactured by Yashara Chemical) was used as a TPPh adduct in place of YP-90L in Example 1, and the softening point was 85%.
When the temperature reached ° C, the end point was reached, and then 49 g of ethylene bisstearic acid amide was added and mixed to obtain 2450 g of a novolak-type phenol resin composition. Comparative 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, and heated on an oil bath with stirring. The reaction was performed until emulsification. Thereafter, concentration is performed under reduced pressure, and when the softening point reaches 85 ° C., the end point is determined. Then, ethylenebisstearic acid amide 2
Novolak-type phenol resin composition 1
400 g were obtained. Comparative Example 2 The same operation as in Comparative Example 1 was carried out except that 37% formalin was changed to 1194 g in the formulation of Comparative Example 1, and 1,000 g of bisphenol A was further added. When the softening point reached 85 ° C., the end point was determined. Add and melt 48 g, 2400 g of novolak type phenol resin composition
I got

Production of Resin-Coated Sand (RCS) To 10 kg of recycled sand heated to 150 ° C., 230 g of each of the resins obtained in the above Examples and Comparative Examples were kneaded for 40 seconds using a speed mixer, and then a 15% aqueous solution of hexamethylenetetramine was added. Add 135g, knead until the sand collapses,
Further, 10 g of calcium stearate was added, mixed for 20 seconds, and discharged from the mixer to obtain RCS. RCS obtained
Was used to visually determine the bending strength, the fusion point, the bend, the expansion characteristics during heat exposure, and the appearance of soot during the measurement of the expansion characteristics. Table 1 shows the results of the RCS characteristics.

[0010]

[Table 1]

[0011]

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 resin composition for a shell mold. It became possible to provide.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Ken Nanami 1500 Ogawa Ogawa, Shimodate-shi, Ibaraki F-term in Shimodate Works of Hitachi Chemical Co., Ltd. CA11 CA12 CA29 CA42 CB02 CB03 CB14 CC02 CC03 CC04 CC07 CC09 HA12 HA13 HB05

Claims (2)

[Claims] 1. A binder for shell molds obtained by co-condensing a phenol adduct of phenols and terpenes and aldehydes. 2. The binder for a shell mold according to claim 1, wherein 5 to 90 parts by weight of a phenol adduct of a terpene is mixed with 100 parts by weight of the phenol.