Sand mold composition for metal casting

• US 4,080,213 A
• Filed: 04/06/1976
• Issued: 03/21/1978
• Est. Priority Date: 04/11/1975
• Status: Expired due to Term

• Current Assignee: Hayashibara Biochemical Laboratories, Inc. (Nagase & Company Limited), Sumitomo Chemical Company Limited
• Original Assignee: Hayashibara Biochemical Laboratories, Inc. (Nagase & Company Limited), Sumitomo Chemical Company Limited
• Inventors: Mori, Atsuo, Nakae, Kiyohiko, Tsuji, Kozo
• Primary Examiner(s): Hayes, Lorenzo B.
• Application Number:
  US05/674,237
• Time in Patent Office: 714 Days
• Field of Search: 106/38.5 R, 106/38.35, 106/214, 106/287 S, 106/193 J, 106/197 C, 106/209
• US Class Current: 106/38.51
• CPC Class Codes: B22C 1/2293 Natural polymers B22C1/24, B22C1/26 take precedence

Abstract

A sand mold composition for the metal casting comprising a molding sand and pullulan as a binder therefor. As compared with prior art, the present composition has following advantages: in the molding step, no gas, dust, noise, or vibration is generated; in the pouring and sand stripping steps, neither noxious gas nor offensive odor is emitted; although the mold has a sufficiently high strength at room temperature for the convenient handling, it is readily broken down after the casting and so renders the knock-out and sand stripping very easy; and the recovered sand can be reused as such, practically without any after-treatment. The molding cycle is comparable to that of conventional oil sand or carbon dioxide-bonded mold.

Claims

1. A sand mold composition for the metal casting comprising a molding sand and pullulan having a molecular weight of 5000 to 2,000,000 as a binder therefor, said pullulan being present in a quantity of 0.1 to 15 parts by weight of pullulan for every 100 parts by weight of molding sand.

2. A composition according to claim 1, wherein the molding sand is silica sand.

3. A composition according to claim 1, wherein moisture content of the composition is 0.5 to 15% by weight based on dry composition.

4. A composition according to claim 1, wherein clay is incorporated in the composition.

5. A composition according to claim 4, wherein the clay is bentonite.

6. A composition according to claim 1, wherein at least one of the ethylene glycol, propylene glycol, glycerol, starch, sodium alginate, carboxymethylcellulose, methylcellulose, hydroxyethylcellulose, acacia, and derivatives thereof is added as a plasticizer for pullulan.

7. A composition according to claim 1, wherein an etherified, esterififed, oxidized, or aminated pullulan is used jointly with or in place of pullulan.

8. A composition according to claim 1, wherein kerosene, gas oil, or silicon oil is added to the composition.

9. A sand mold for the metal casting preapred from a molding sand and pullulan having a molecular weight of 5,000 to 2,000,000 as a binder therefor, said pullulan being present in a quantity of 0.1 to 15 parts by weight of pullulan for every 100 parts by weight of molding sand.