JPH05169186A - Binder composition for molding sand - Google Patents

Abstract

PURPOSE:To provide a binder composition, in which the usable time is prolonged at the time of mixing sand and resin and the excellent strength as a mold is exhibited and in the case of pouring molten iron into the sand mold, even if the resin is thermal-decomposed, nasty smell is not generated. CONSTITUTION:This binder composition for uniform molding sand is consisting of (a) organic polyisocyanate compound (diphenyl ethane diisocyanate, etc.) (b) 100wt.% parts of bisphenol compound (bisphenol A, etc.) (c) 50-1000wt.% parts of polyole compound (polyester polyole, etc.). The quantity of (a) is made to 0.3-3 equivalents of the isocyanate group in the (a) per one equivalent of active hydrogen in (b)+(c). Diluting agent (toluene, etc.) is added to this composition, and at the time of mixing the binder and the sand, curing agent (tertiary amine) is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a binder composition for molding sand, which is a self-curing binder for room temperature self-hardening material, which is fast-curing by adding a curing agent and has a low odor during casting. Is.

[0002]

2. Description of the Related Art Conventionally, binders (binders) used for manufacturing sand molds for castings are roughly classified into two types: inorganic binders and organic binders. Examples of the former method of using an inorganic binder include, for example, a method of blowing CO ₂ gas into sand containing water glass to cure the sand, a method of blending water glass and calcium silicate into the sand to cure, and sand. There is a method of compounding cement and further adding water to cure it. In the latter method using an organic binder, for example, a furan resin or a phenol resin is mixed with sand, and the mixture is cured with a strong acid curing agent such as paratoluenesulfonic acid, xylenesulfonic acid, sulfuric acid or phosphoric acid, and then sand type. And a method of curing the sand mold by a urethanization reaction that occurs by mixing a curing agent composed of polyisocyanate and a basic catalyst with a phenolic compound.

[0003]

However, in the former hardening method using an inorganic binder, when the casting is taken out after the molten iron is poured into the mold made of the casting sand and the casting is taken out, the disintegration property of the casting sand mold is deteriorated. Is poor, and there is a problem that workability is significantly reduced. In addition, of the curing methods using an organic binder, the curing method using a strong acid uses a strong acid as a curing agent, and therefore, for example, when sea sand is used, curing failure tends to occur depending on the type of sand. On the other hand, in the curing method using the urethanization reaction, it is not necessary to select sand, and although the binder is excellent in the pot life when mixing sand and resin, and the strength development after molding, When it is put into a sand mold, the resin after curing is thermally decomposed, and the generation of formaldehyde-type or phenol-type odor is a problem. The present invention, the extension of the pot life at the time of sand and resin mixing, and also excellent in the expression of strength as a mold, and, when the iron bath is put into the sand mold, even if the resin after curing is thermally decomposed. An object of the present invention is to provide a binder composition for a homogeneous casting sand that is odorless.

[0004]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned drawbacks, the present inventors have developed a binder composition for homogeneous foundry sand, and arrived at the present invention. That is, the present invention provides (a) an organic polyisocyanato compound,
(B) General formula I

[0005]

[Chemical 2] (However, R ₁ and R ₂ are respectively H, CH ₃ or C ₂ H
₅ is shown. ) Is a bisphenol compound containing a phenolic hydroxyl group, and (c) a binder compound for homogeneous casting sand comprising a polyol compound capable of dissolving the bisphenol compound of (b) above.

First, as the organic polyisocyanato compound (a) used in the present invention, any polyisocyanato compound generally widely used as a raw material for polyurethane can be used. Examples of these compounds include aliphatic diisocyanates such as hexamethylene diisocyanate and lysine diisocyanate; 4,4′-dicyclohexylmethane diisocyanate, bis (isocyanatomethyl) cyclohexane, 3- (2′-isocyanate). Alicyclic diisocyanato such as naphthocyclohexyl) propyl isocyanato, isopropylidene bis (cyclohexyl isocyanato), isophorone diisocyanato; p-phenylene diisocyanate, 2,4-
Tolylene diisocyanate, a mixture of 2,4- and 2,6-tolylene diisocyanate, crude tolylene diisocyanate, tolidine diisocyanate, dianisidine diisocyanate, diphenyl ether diisocyanate, diphenylmethane diisocyanate or its dimethyl Derivatives, aromatic diisocyanates such as xylylene diisocyanate, 1,5-naphthalene diisocyanato, and chlorophenylene-2,4-diisocyanato; other triphenylmethane triisocyanato, tris (phenylisocyanato) thiophosphate, polymethylene polyphenylene Aromatic polyisocyanate such as polyisocyanate, or the above isophorone diisocyanate, tolylene diisocyanate, urethane such as diphenylmethane diisocyanate, carbodiimide and / or modified biuret modified. It is. Among these,
Aromatic diisocyanates or aromatic polyisocyanates are preferred, with diphenylmethane diisocyanate, triphenylmethane triisocyanate and mixtures thereof being particularly preferred.

The bisphenol compound (b) used in the present invention includes bisphenol A and bisphenol F. In addition, polyhydric phenols having two or more phenolic hydroxyl groups in the molecule, for example, hydroquinone, methylhydroquinone, catechol, resorcinol, 1,2-dihydroxynaphthalene, 1,3-dihydroxynaphthalene, 1,4-dihydroxynaphthalene pyrogallol , 2,4-trihydroxybenzene, etc., having two or more phenolic hydroxyl groups on the same aromatic ring; 1,5-
Dihydroxynaphthalene, 1,6-dihydroxynaphthalene, etc., whose aromatic skeleton forms a molecular skeleton, and which has two or more hydroxyl groups on different aromatic rings; bisphenol A,
A product in which phenol such as bisphenol F is bonded only by using an arbitrary aliphatic hydrocarbon, or a polymer (for example, Milex: trade name, manufactured by Mitsui Toatsu Chemicals, Inc.) having a molecular weight of 200 to 2000. Is mentioned. Further, it is possible to use two or more kinds of polyhydric phenols having two or more phenolic hydroxyl groups in the molecule and mix them at an arbitrary ratio to use.

Further, in the present invention, the polyol compound (c) which dissolves the above bisphenol compound is an ethylene oxide or propylene oxide adduct of bisphenol A and bisphenol F, and a polyester polyol. It can be used together. Examples of polyester polyols include diols such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, and ethylene oxide and / or propylene oxide adducts of bisphenol A, and adipic acid, phthalic anhydride, isophthalic acid, maleic anhydride, fumaric acid, etc. Polyester polyol having a molecular weight of 200 to 2000, which is a compound having two alcoholic hydroxyl groups at both ends, which is obtained by the condensation reaction with the polybasic acid. In addition, if necessary, within a range that does not hinder the dissolution of the bisphenol compound, for example,
Ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol having a molecular weight of 150 to 700, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol having a molecular weight of 200 to 1000, glycerin, diglycerin,
Ethylene oxide adduct and / or propylene oxide adduct of glycerin having a molecular weight of 100 to 2000, 1,4-butanediol, 1,2-butanediol, polyoxytetramethylene, glycol, trimethylolpropane, ethylene oxide of trimethylolpropane and / or Or propylene oxide adduct, bisphenol A and bisphenol F
Alkylene-based polyols such as bisphenol ethylene oxide adducts and / or propylene oxide adducts (the ethylene oxide adduct and / or propylene oxide adduct of the ethylene oxide and propylene oxide adducts do not limit the present invention) Or an ethylene oxide and / or propylene oxide adduct of ammonia such as polyether polyol resin, triethanolamine, triisopropanolamine and the like, alkylamine (carbon of the alkyl group such as N-butyldiethanolamine, N-butyldiisopropanolamine and the like). Ethylene oxide and / or propylene oxide adduct having a number of 1 to 18), ethylene oxide and / or propylene oxide adduct of aromatic amine such as N, N-dihydroxyethylaniline, and the like. Diamine, ethylene glycol and / or propylene oxide adducts of polyalkylene polyamines such as triethylene diamine, butyl glycidyl ether, adducts of substituted monooxysilane compounds such as styrene oxide with alkanol amines such as diethanol amine and diisopropanol amine The polyols containing tertiary nitrogen can also be added alone or in combination.

Here, the compounding amount of the organic polyisocyanate compound (a) with respect to the bisphenol compound (b) and the polyol compound (c) is such that the amount of the organic polyisocyanate compound is 1 equivalent of active hydrogen of the bisphenol compound and the polyol compound. Isocyanato group is usually 0.3 to 3 equivalents,
It is suitable that the amount is preferably 0.6 to 1.5 equivalents. The blending amount of the bisphenol compound (b) and the polyol compound (c) is usually 50 to 1000 parts by weight, preferably 100 to 500 parts by weight, based on 100 parts by weight of the bisphenol compound. If this amount is less than 50 parts by weight, the bisphenol compound will precipitate and become non-uniform, and if it exceeds 1000 parts by weight, the strength development as a template will be poor.

Further, in the present invention, a diluent may be used together for the purpose of lowering the viscosity from the viewpoint of workability when mixing sand and resin. As the diluent, toluene, an organic solvent such as xylene, dibutyl malate, an aliphatic compound such as dibutyl fumarate, dibutyl phthalate,
An aromatic compound such as diallyl phthalate is used. Further, a tertiary amine which is a known curing agent can be used for curing the above mixture. Examples thereof include trimethylamine, dimethylethylamine, monomethyldiethylamine, triethylamine, diethylpropylamine, monoethylpropylamine, tripropylamine, and gasified products thereof. The binder composition for a homogeneous foundry sand of the present invention has an extension of the pot life at the time of mixing the sand and the resin, and is excellent in the expression of strength as a mold, and even if the mold is thermally decomposed by adding iron hot water. It has a low odor.

[0011]

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples. In the following, "part" and "%" are based on weight. -Production of polyester polyol Production Example 1 146 parts of adipic acid and 808 parts of 2,2'-di (4-hydroxyethoxyphenyl) propane were esterified by a usual method,
Polyester polyol A was obtained.

Production Example 2 830 parts of isophthalic acid and 640 parts of diethylene glycol were esterified by a usual method to obtain a polyester polyol B having a molecular weight of 1500.

Production Example 3 100 parts of 85% paraformaldehyde and 140 parts of phenol were reacted by a known method and then dehydrated under reduced pressure to obtain a polyhydric phenol. Ethyl cellosolve acetate as a diluent 5
Phenol resin D was obtained by mixing 0 parts.・ Bisphenol compound and polyol compound

Formulation Example 1 100 parts of the polyester polyol A of Production Example 1 was added to 50 parts of bisphenol A, mixed at 100 ° C., and 100 parts of toluene was added in order to reduce the resin viscosity to a level that does not hinder the work. Obtained.

Formulation Example 2 100 parts of the polyester polyol B of Production Example 2 was added to 50 parts of bisphenol F, mixed at 100 ° C., and 100 parts of xylene was added in order to reduce the resin viscosity so that there is no hindrance to work. Obtained.

Blending Example 3 50 parts of bisphenol A and propylene oxide adduct of bisphenol A (brand KB280, manufactured by Mitsui Toatsu Chemicals, Inc.)
50 parts was added and mixed at 100 ° C., and 50 parts of dibutyl maleate was added in order to reduce the resin viscosity so that there is no hindrance to work, and Resin C was obtained.

Examples 1 to 3 100 parts of foundry sand were put in a kneader, 1.5 parts of the resins obtained in each of Examples 1 to 3 were added, and the mixture was sufficiently kneaded for 30 seconds. Then, an organic polyisocyanato compound was added. 1.0 part of diphenylmethane diisocyanate was added and kneaded for 30 seconds. This kneading sand was poured into a cylindrical mold (inner diameter 5 cm, height 13 cm) and cured by flowing a gas of triethylamine as a curing agent to obtain a test piece. Also, by the same work,
After producing a mold for an axle, a casting was cast using this mold. Next, the bending strength of the obtained test piece was measured immediately after flowing the gas of triethylamine and after 1 hour. Regarding the mold, the odor during casting and the odor of the casting was confirmed by the sense of smell. Furthermore, the beauty of the casting surface was visually confirmed. The results are shown in Table 1 (Table 1). The degree of odor and beauty was evaluated in three grades (○, Δ, ×). In all cases of Examples 1 to 3, the bending strength, odor and beauty were good.

Comparative Example 1 A test piece, a mold and a casting were obtained in the same manner as in Example 1 except that the phenol resin D obtained in Production Example 3 was used instead of the resin A. Each of these was tested in the same manner as in Example 1, and the results are shown in Table 1 (Table 1). The bending strength of the test piece is good,
Generation of odor and deterioration of the beauty of the casting surface were observed.

[0019]

[Table 1]

Examples 4 to 6 100 parts of foundry sand were placed in a kneader, 1.5 parts of the resins obtained in each of the formulation examples 1 to 3 were added, and the mixture was sufficiently kneaded for 30 seconds. Then, an organic polyisocyanato compound was prepared. Add 1.0 part of diphenylmethane diisocyanate and knead for 30 seconds, then add 0.015 part of triethylamine, which is a curing agent,
Kneaded for 30 seconds. This kneading sand was put into a cylindrical mold (inner diameter 5 cm,
The test piece was obtained by injecting it to a height of 13 cm 2 and curing it. In addition, after making a mold for an axle by the same operation, a casting was cast using this mold. Next, the bending strength of the obtained test piece was measured after 30 minutes and 1 hour. Regarding the mold, the odor during casting and the odor of the casting was confirmed by the sense of smell. Furthermore, the beauty of the casting surface was visually confirmed. The results are shown in Table 2 (Table 2). Example 4
In all cases, the bending strength, odor and beauty were good.

Comparative Example 2 When the phenol resin D obtained in Production Example 3 was used in place of the resin A in Example 4, gelation occurred immediately,
It was difficult to make the desired test piece and mold.

[0022]

[Table 2]

[0023]

EFFECTS OF THE INVENTION When the binder composition for a homogeneous foundry sand of the present invention is used, the pot life is prolonged when the sand and the resin are mixed, and the strength as a mold is excellent, and the iron hot water is used. It is clear from Tables 1 and 2 that even when the resin after curing is thermally decomposed when it is put into the sand mold, it has a low odor.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical display location C09J 175/04 JFB 8620-4J (72) Inventor Hideo Arikawa 1900, Togo, Mobara-shi, Chiba Mitsui Toatsu Kagaku Co., Ltd. (72) Inventor Satoshi Furusawa 1900 Togo, Mobara-shi, Chiba Mitsui Toatsu Chem

Claims (1)

[Claims] 1. (a) an organic polyisocyanato compound,
(B) General formula I (Chemical formula 1) (However, R ₁ and R ₂ are respectively H, CH ₃ or C ₂ H
₅ is shown. ) A bisphenol compound having a phenolic hydroxyl group represented by the following), and (c) a binder composition for homogeneous casting sand comprising a polyol compound capable of dissolving the bisphenol compound of (b) above.