JPH0460520B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a method for cleaning metal, plastic or wood surfaces, in particular the surfaces of metal mold model elements.

[Conventional technology]

As is known, when molten metal is poured into a molding cavity and allowed to cool, the metal assumes the shape of the cavity defined by the walls of the cavity and the projecting surfaces extending and suspended within the cavity. In metal casting, sand bonded with hardened resin is used to form a strong sand mold or core to produce metal products of various shapes. In the field of casting technology, such casting molds and cores are respectively referred to as "membrane molds (patterns)".
and a further "molding" element called a "core box."
Although the term "core" is used, a core is of course a model or a molding element.
Thus, when the term "model" is used in this application, it is intended to refer to both an element for molding a sand mold and an element for molding a sand core.

Model elements, or models and cores, are generally made of metal, thermoset plastics and wood, typically iron, steel, aluminum, polyurethane resins, epoxy resin alloys, kirksite alloys, stainless steel, Manufactured from hard wood and other materials. Those pattern elements that come into repeated contact with the cured resin binder are those that benefit from the method of the present invention.

In the field of metal casting technology, molds and cores are made by introducing a mixture of sand and resin binder into a suitable pattern element. This mixture hardens to form a strong molding that is used to receive and mold the molten metal. A variety of resin-based binders are used to make sand molds, and the curing of these resins is achieved by curing catalysts (e.g., acid catalysts for acid-curable binders, and acid catalysts for acid-curable binders; is achieved using amine catalysts). Although many other types of resin-based binders are used, in the field of foundry technology furan and phenolic urethane binders are probably the most widely used to create strong molds. There is. Typical resin binders used to make sand cores and molds for casting are furan-based non-bake binders, phenolic non-bake binders, phenol urethane resin-amine binders, and phenol. Resin hot box binder, furan resin hot box binder,
Furan resin - sulfur dioxide binder, acrylic resin -
Sulfur dioxide binders, epoxy acrylic resin-sulfur dioxide binders, alkyd oil binders, and others.

[Problem that the invention seeks to solve]

As a result of repeated use of model elements,
A film or residue is deposited on the surface. This film, or residue, consists of the reaction products of a resinous binder and the catalyst used to cure the resin, and is formed by the reaction of the sand contaminants and curing catalyst with the model surface. It is assumed that it contains reaction products. It is necessary to periodically remove this residue from the pattern elements, and the buildup of such residue is a problem in the field of metal casting technology. In the past, a commonly used method of cleaning model elements was to sandblast them. This cleaning method is not completely satisfactory because it is time consuming and can damage the metal, plastic or wooden model surfaces if not handled carefully. High-pressure sandblasting poses potential dangers to workers and further disadvantages, such as the risk of silicosis.

It is therefore a principal object of this invention to provide an improved method for cleaning metal surfaces.

Another object of the present invention is to provide a simple and effective method for cleaning metal, plastic or wood surfaces that have deposits of residues resulting from curing a resin in contact with the metal, plastic or wood surface. The goal is to provide the following.

Yet another object of this invention is to provide a method for cleaning metal, plastic or wood surfaces that does not use high temperature, high pressure equipment, aggressive cleaning agents or aggressive solvents.

[Means and effects for solving problems]

Surprisingly, the residue deposited on metal, plastic, and wood surfaces as a result of curing the resin in contact with the metal, plastic, and wood surfaces was made from the N-vinyl-2-pyrrolidone/maleic acid copolymer. It has been found that the cleaning composition can be easily and effectively removed by applying thereto a cleaning composition consisting of: The cleaning composition is preferably applied to the "soiled" metal in solution by any suitable method such as brushing or spraying it or dipping the soiled surface in the cleaning solution. Applied to plastic or wood surfaces. Although water is the preferred solvent for making cleaning solutions, solvents other than water may also be used. Such solvents include, for example, methanol,
Included are ethanol, methyl ethyl ketone, butylacetone, N-methylpyrrolidone, phenoxyethanol, dimethylformamide, and others. The cleaning solution dries to a sufficiently dry film that can be peeled off along with any undesirable cured resin residue from the surface being treated.

Thus, the present invention provides a method of applying N-vinyl-2-pyrrolidone and maleic acid to the surface of metal, plastic, or wood where there is a residue resulting from curing the resin while contacting the metal, plastic, or wood surface. applying a solution of a copolymer of N-vinyl-2-pyrrolidone and maleic acid to form a thin film, and separating said film from a metal, plastic or wood surface. It's in the cleaning method.

Aqueous solutions of N-vinyl-2-pyrrolidone/maleic acid copolymers are commercially available from GAF Corporation of New York, New York under the designation Drug CD260. U.S. Pat. No. 4,424,079 describes an N-vinyl-2-pyrrolidone/maleic acid copolymer and method for making the same, the disclosure of which is incorporated herein by reference. be. In US Patent No. 4,424,079,
N-vinyl-2-pyrrolidone/maleic acid copolymers are described as useful for removing rust from metal surfaces. Commercially available CD260N-vinyl-2
- Pyrrolidone/maleic acid copolymers are available from high/low density polyethylene, polypropylene, cellulose acetate, rigid/plasticized vinyl, cellulose acetate butyrate, nylon, polymethacrylic acid, according to the distributor G.A.F. Corporation. Thermoplastics such as methyl, polytetrafluoroethylene, polystyrene, polycarbonate, acrylonitributadiene styrene, and polyvinyl chloride, and thermoplastics such as phenol formaldehyde, melamine formaldehyde, alpha-cellulose phenol formaldehyde, polyester, epoxy and silicone. They have been reported and promoted as having the ability to "self-peel" from a wide variety of types of surfaces, including hardenable materials.

The viscosity of the metal, plastic or wood cleaning solution can be adjusted as desired for ease of application, as described in US Pat. No. 4,424,079. Generally, the viscosity is about 2
Aqueous solutions of copolymers in the range of ~75 Pas (2000-75000 cP) are convenient for use. N-vinyl-2-
The molecular weight of the pyrrolidone/maleic acid copolymer can vary as described in the US patent specification, but generally
Molecular weight above 15000 makes better thin films.

After application of the cleaning solution, the cleaning solution dries to form a solid peelable film. Dry at room temperature for about 30~
It takes 120 minutes to complete, but you can speed up the drying process by applying heat, such as blowing warm air on top of it, or by using forced air. Surfactants can also be added to improve the wetting properties of the N-vinyl-2-pyrrolidone/maleic anhydride copolymer on the pattern surface containing the residue release agent. Silica compounds are added to improve the thickness of the film and to make the film thixotropic.

〔Example〕

The following examples illustrate the advantages of the invention.

Example 1 To demonstrate the cleaning ability of the N-vinyl-2-pyrrolidone/maleic acid copolymer, a foundry core with a significant amount of resin deposit or residue on the surface was used. The core removal residue is due to the use of furan resin binder and sulfur dioxide catalyst therein. The residue is 0.05~0.10mm thick
It was a hard black film in the range of 2 to 4 mils, and was firmly attached to the surface of the core, making it difficult to remove the core. The core made by the above-mentioned core machine is a core for a water jacket for the head of an internal combustion engine.

Brush an aqueous solution of N-vinyl-2-pyrrolidone/maleic acid copolymer to approximately 0.51 to 0.76 mm (20 to
30mil) thickness. The applied solution is 21
Dry for 2 hours at 70 °C. The dry coating solution is blown off with an air hose, which
More than 70% of resin residue was removed. A good clean core surface was observed where the polymer treatment solution had stripped off the black furan-sulfur dioxide residue.

Example 2 A wooden model for casting a machine housing using sand bound with a furan-based no-bake binder was cleaned in accordance with the present invention. The wooden model has a diameter of approximately 0.013 to 0.051 mm (0.5 to
A film of residue 2 mils thick was present. N-
The vinyl-2-pyrrolidone/maleic acid copolymer aqueous solution was brushed to a thickness of about 30 mils. This cleaning composition dries in 2 hours,
Over 90% of the residue was then removed by blowing off the dry film of cleaning solution with an air hose.

Example 3 A cold rolled steel panel was coated with a thin film of furan resin foundry binder, methyl ethyl ketone peroxide and sulfur dioxide. 0.05~ to replicate deposits or residues observed on the cast model
A 0.10 mm (2-4 mil) thick deposit was obtained.
An aqueous solution of N-vinyl-2-pyrrolidone/maleic acid copolymer was brushed onto the panel. After drying for 4 hours at room temperature, approximately 90% of the deposits were removed by spraying with an air hose.

Example 4 A cast iron tencil core used to cure hot box stencil core specimens was cleaned with a 25% solution of N-vinyl-2-pyrrolidone/maleic acid cleaning solution. The core had a thin film of resin deposited on it after more than two weeks of treatment. A cleaning solution was sprayed onto the core to a thickness of about 20-30 mils and allowed to dry. Over 80% of the deposits were removed by blowing away the dried coating with an air hose.

The effectiveness of using N-vinyl-2-pyrrolidone/maleic acid copolymer to remove cured resin residue from the material is seen in the examples above. This discovery that N-vinyl-2-pyrrolidone/maleic acid copolymers effectively remove residues or coatings deposited on surfaces resulting from repeated contact with cured resin-based materials has not been previously reported. This was completely surprising and unexpected in view of its "self-peel" properties for many plastics.

Those modifications and equivalents which come within the spirit of the invention are considered to be a part thereof. The present invention is therefore particularly useful in the field of foundry technology for cleaning surfaces that have accumulated residue from the curing of a curing resin by repeated contact with such resin. It is also broadly applicable to other similar cleaning operations where residues are present.

Claims (1)

[Scope of Claims] 1. A method for cleaning the surface of metal, plastic or wood on which residues have been deposited due to curing of a resin while contacting the surface, comprising: by applying a solution of a copolymer of N-vinyl-2-pyrrolidone and maleic acid to a metal, plastic or wood surface and drying said solution of a copolymer of N-vinyl-2-pyrrolidone and maleic acid to form a thin film. form,
and separating said film together with said residue from said metal, plastic or wood surface. 2 The accumulation of the residue is caused by a furan-based non-bake binder, a phenolic non-bake binder, a phenolic urethane-amine binder, a phenolic hot-box binder, a furan-based hot-box binder, or furan-dioxide binder. Sulfur binder, acrylic
A resin binder for sand cores or molds selected from the group consisting of sulfur dioxide binders, epoxy acrylic-sulfur dioxide binders and alkyd oil binders is cured in contact with said surface. A cleaning method according to claim 1, which is derived from. 3. A method for cleaning a cast model element having deposits of residue derived from curing a sand binder resin in contact with the cast model element, the method comprising: applying N-vinyl-2 to the cast model element; - applying a solution of a copolymer of pyrrolidone and maleic acid and drying said solution of a copolymer of N-vinyl-2-pyrrolidone and maleic acid to form a thin film;
2. A method as claimed in claim 1, comprising: and separating said film together with said residue from a cast model element. 4. Claim 3, wherein the accumulation of the residue is caused by curing the furan-based sand binder or the phenolic urethane sand binder while contacting the surface of the cast model element. Cleaning method described in section. 5. For cleaning cast model elements with deposits of residues resulting from curing of a mixture of sand and binder therefor in contact with the cast model elements Cleaning method described. 6. The cleaning method according to claim 3, wherein the cast model element is a metal cast model element.