JPH09169998A - Cleaning agent and cleaning method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaning agent containing γ-butyrolactone, an ethylene glycol monoalkyl ether, a mineral acid and water, free from adverse effect on organisms and environment, having excellent peeling action on coating film and useful for the cleaning of metal surface, etc. SOLUTION: This cleaning agent contains (A) preferably 10-30wt.% of γ- butyrolactone, (B) preferably 25-55wt.% of an ethylene glycol monoalkyl ether such as ethylene glycol monobutyl ether, (C) preferablyj 5-10wt.% of a mineral acid such as nitric acid, (D) water and preferably further (E) a surfactant such as a sodium alkylbenzenesulfonate. It is preferable to immerse a metallic structure such as aluminum sash coated with a clear lacquer in the cleaning agent to peel the coating film on the surface of the metallic structure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning agent suitable for, for example, removing a clear lacquer film on the surface of an aluminum sash and a cleaning method using the cleaning agent.

[0002]

2. Description of the Related Art On the surfaces of various metal structures, for example, a coating film such as a lacquer or a paint is formed in order to enhance aesthetic appearance and protect the surface. When these metal structures are commercialized, defective products may be generated, or the type and color of the coating film may be forced to be changed according to customer requirements. In such a case, discarding a defective product or discarding a product exchanged and taken according to a request of a customer wastes valuable resources, causes economic loss, and is preferable. Not that.

[0003] Therefore, the defective metal structure and the withdrawn metal structure are regenerated and / or repainted without being discarded. Before regenerating and / or repainting, the surface of the metal structure is rejected. Must be peeled off. In order to remove this coating film, a release solvent containing a chlorinated hydrocarbon represented by methylene chloride as a main component has been widely used.

[0004]

For example, chlorinated hydrocarbons such as methylene chloride generally have a low boiling point and easily evaporate even in a normal environment such as normal temperature and normal pressure. Is not wasted, and has adverse effects on the human body and many animals and plants,
Furthermore, wastewater after use may cause environmental destruction, and wastewater after use has recently been strictly regulated by law, and the emergence of a coating film stripping agent in place of these is urgently required.

According to the present invention, the present inventors have an effect of removing a coating film on a metal surface (hereinafter, also referred to as a coating film removing effect).
Is large, but in place of the conventional chlorinated hydrocarbons that cause environmental damage,
Non-chlorine, which has a film peeling action equal to or better than that of conventional film peeling agents containing chlorinated hydrocarbons, and does not adversely affect humans and many other animals and plants, and has substantially no risk of environmental destruction As a result of intensive studies to develop a coating film release agent, a composition obtained by mixing materials that are difficult to evaporate, have low toxicity to living organisms, and have high safety achieves the above-mentioned purpose. It has been made based on this new finding, with the new finding that it is possible.

[0006]

Means for Solving the Problems That is, the first invention comprises gamma (γ) -butyrolactone, ethylene glycol monoalkyl ether, mineral acid and water, and further contains a surfactant if desired. It is a cleaning agent. The second invention is the detergent of the first invention,
The cleaning method is characterized by immersing a metal structure having a coating film on the surface and peeling the coating film on the surface of the metal structure. In the third invention, a metal structure having a coating film on its surface is dipped in the cleaning agent of the first invention, which is put in a cleaning treatment tank, and then the metal structure is washed in a water washing treatment tank, This is a cleaning method in which the washing liquid in the washing treatment tank is circulated to the cleaning treatment tank and reused.

The ethylene glycol monoalkyl ether to be contained in the detergent of the present invention is preferably ethylene glycol monomethyl ether, ethylene glycol monoethyl ether or ethylene glycol monobutyl ether. Of these, ethylene glycol monobutyl ether (also known as butyl cellosolve) is most preferred. As the mineral acid contained in the detergent of the present invention, nitric acid is most preferred.

Further, by further adding a surfactant to the detergent of the present invention, the spreadability of the detergent on the metal structure is further increased, thereby further increasing the coating film peeling action. It is preferable to add a surfactant because the washing effect during the water washing process can be enhanced. As the surfactant which is optionally contained in the detergent of the present invention, an alkylbenzene sulfonate surfactant is preferable. As the alkylbenzenesulfonate surfactant, a surfactant containing sodium alkylbenzenesulfonate is most preferred.

The preferred content of each component in the detergent of the present invention is such that the content of each of γ-butyrolactone, ethylene glycol monoalkyl ether and mineral acid is 10 to 30% by weight, 25 to 55% by weight and 5 to 55% by weight.
The content is 10% by weight, the balance is water, and the water content is at least 15% by weight, and the total amount of gamma-butyrolactone and ethylene glycol monoalkyl ether is 40 to 40%.
70% by weight. If these contents deviate,
The peeling of the coating film is not easy. Among these contents, the water content is particularly important. When the water content is less than 15% by weight, the effect of peeling off the coating film is significantly reduced. Further, the amount of the surfactant to be added is usually about 1 to 5 parts by weight based on 100 parts by weight of the detergent of the present invention before the surfactant is added.

Each of the substances contained in the detergent of the present invention has a high boiling point, is hard to evaporate at room temperature and atmospheric pressure, and each is a substance with high safety and reacts with each other. Therefore, the cleaning agent of the present invention has substantially no risk of environmental pollution or environmental destruction. There is no particular limitation on the preparation method such as the order of addition of the detergent of the present invention,
Usually, for example, γ-butyrolactone and ethylene glycol monoalkyl ether are added to water to dissolve, then a mineral acid is added, and then, if necessary, a surfactant is added and stirred to obtain a stable and uniform solution. Is obtained as

The coating film on the surface of the metal structure which can be peeled off by the cleaning method of the present invention is not particularly limited. For example, a coating film formed by a vinyl resin paint, a latex paint, or the like can be used. The cleaning method of the present invention is preferably used for peeling a coating film formed by a lacquer such as a clear lacquer and a vinyl resin paint.

Representative examples of the types of metals constituting the metal structure include aluminum and steel. Although there is no particular limitation on the structure, typical examples include sashes used for window frames and aggregates such as prefabricated houses, frame materials and floor materials. The cleaning method of the present invention is preferably used for peeling a coating film formed by lacquer on the surface of an aluminum sash.

In the cleaning method of the present invention, the metal structure having a coating film on its surface is subjected to a cleaning treatment, for example, by immersing the metal structure in the cleaning bath of the present invention. Usually, the temperature of the detergent is preferably about 35 to 65 ° C, and particularly preferably about 40 to 60 ° C.

The dipping time varies depending on the temperature of the cleaning agent and the type and thickness of the coating film, but is, for example, about 5 to 10 minutes at about 40 to 60 ° C. and substantially completely peeled off. To be done. The metal structure on which the coating film on the surface was peeled off by the cleaning method of the present invention was removed from the cleaning agent,
Next, it is immersed in water or a washing liquid filled in the washing treatment tank, and is subjected to washing treatment to remove coating residue and a detergent adhering to the surface of the metal structure. Usually, the temperature of the water in the water washing treatment is preferably about 35 to 65 ° C, particularly preferably about 40 to 60 ° C. In the water washing treatment, it is preferable to vibrate or swing the metal structure immersed in water or the washing liquid. The metal structure that has been subjected to the water-washing treatment is taken out of the water-washing liquid, and then jetted with water. Completely removed.

Since the cleaning treatment in the cleaning method of the present invention is performed at a considerably high temperature for a long time in an open cleaning treatment tank, a large amount of water evaporates from the cleaning agent. Since the detergent of the present invention is mixed in the washing liquid when the metal structure from which the coating film has been peeled off by the cleaning treatment in the cleaning method of the present invention is mixed, the washing liquid is added to the cleaning treatment tank in a timely manner. By circulating, it is possible to replenish moisture evaporated from the detergent in the cleaning treatment tank, and it is possible to collect and reuse the components of the detergent.

The cleaning tank and the washing tank are connected to each other by a circulation pipe, and the washing liquid in the washing tank is circulated to the cleaning tank via the circulation pipe. In addition, a solid-liquid separation means such as a strainer can be interposed in the circulation pipe, if desired, in order to remove coating residue in the washing liquid, which is preferable.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS For example, the cleaning agent of the present invention and water are filled in each of a cleaning treatment tank and a water washing treatment tank, and each is maintained at a predetermined temperature. A metal structure having a coating film on the surface is immersed in a cleaning treatment tank to be subjected to a cleaning treatment, and the coating film is peeled off. Then, the metal structure is taken out of the detergent to remove water or water in a washing treatment tank. It is immersed in a washing solution and subjected to a washing process to remove the coating residue and the detergent adhering to the surface. The metal structure that has been subjected to the water washing process is taken out of the washing solution, and water is jetted to the metal structure to remove coating residue and the washing solution adhering to the metal structure. The liquid from which the coating residue has been removed from the water washing liquid is returned to the cleaning tank and reused.

[0018]

【Example】

Example 1 Preparation of detergent 12 parts by weight of γ-butyrolactone, 50 parts by weight of ethylene glycol monobutyl ether and nitric acid (specific gravity 1.
50) 8 parts by weight are added to 30 parts by weight of water and stirred to obtain a detergent as a uniform solution. Then, 2 parts by weight of sodium alkylbenzenesulfonate is added to the detergent and stirred to form a uniform solution. Obtained. In addition, the said each raw material used the commercial item as it was.

Example 2 Cleaning treatment of metal structures having a coating film on the surface, washing with water, and recovery of washing liquid An aluminum sash having a clear lacquer coating film on the surface is subjected to a cleaning treatment and then subjected to a water washing treatment. Then, the water-washed liquid after the water-washing treatment was collected, and the water-washed liquid was circulated to the above-mentioned detergent and reused in the cleaning treatment. The cleaning liquid and the water of the present invention obtained in the above-described Example 1 are respectively filled in the cleaning processing tank and the water cleaning processing tank, and the cleaning agent and water (the water cleaning liquid in the second and subsequent water cleaning processing) are During the cleaning treatment and the water washing treatment, the temperature was maintained at about 43 ° C., respectively. An aluminum sash having a clear lacquer coating on the surface (thickness of the coating: about 7 μm) was immersed in the cleaning agent of the present invention obtained in Example 1 above. Observation with the naked eye showed that, as in the case of immersion in a conventional release agent containing methylene chloride as a main component for 15 minutes, 1
After 0 minute, the coating was substantially completely peeled off.

After the cleaning process is completed, the aluminum sash removed from the cleaning agent is immersed in water or a rinsing liquid for 5 minutes in a rinsing liquid tank and vibrated vertically while the aluminum sash is removed from the rinsing liquid. The aluminum sash was taken out, then jet-sprayed with water and subjected to a post-treatment, and visually observed. As a result, substantially no coating residue was adhered to the aluminum sash. The rinsing liquid after the rinsing treatment was circulated to the cleaning tank via a circulation pipe as needed to supply water evaporated from the cleaning liquid in the cleaning tank and to collect and reuse the components of the cleaning agent. As a result, it was possible to peel off the coating film of the aluminum sash for 3 days without supplying water and a detergent other than the washing solution to the cleaning treatment tank.

Example 3 20 parts by weight of γ-butyrolactone, 30 parts by weight of ethylene glycol monobutyl ether and nitric acid (specific gravity: 1.
50) 8 parts by weight are added to 42 parts by weight of water and stirred to obtain a detergent as a uniform solution. Then, 2 parts by weight of sodium alkylbenzenesulfonate is added to the detergent and stirred to form a uniform solution. Obtained. In addition, the said each raw material used the commercial item as it was. Using the detergent to which this surfactant has been added, the temperature of the detergent is increased to 40 ° C. and 5 ° C.
At 0 ° C., the coating on the aluminum sash surface was peeled off in the same manner as in Example 2. At 40 ° C. and 50 ° C., the coating was substantially completely stripped in 7 minutes and 3 minutes, respectively. Further, the coating film of the aluminum sash could be peeled off for 3 days without supplying water and a detergent other than the washing liquid to the cleaning treatment tank.

[0022]

Industrial Applicability The present invention has a great effect of removing a coating film, but is different from a conventional coating film removing agent containing a chlorinated hydrocarbon as a main component, which causes environmental destruction and adversely affects living organisms. Therefore, the coating film removing action is equal to or more than the conventional coating film removing agent containing a chlorinated hydrocarbon as a main component, and has substantially no risk of environmental destruction, and
Detergents and cleaning methods that do not adversely affect living organisms.

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Claims (13)

[Claims] 1. A detergent comprising gamma-butyrolactone, ethylene glycol monoalkyl ether, mineral acid and water. 2. The detergent according to claim 1, wherein the ethylene glycol monoalkyl ether is ethylene glycol monomethyl ether, ethylene glycol monoethyl ether or ethylene glycol monobutyl ether. 3. The detergent according to claim 1, wherein the ethylene glycol monoalkyl ether is ethylene glycol monobutyl ether. 4. The detergent according to claim 1, wherein the mineral acid is nitric acid. 5. The contents of gamma-butyrolactone, ethylene glycol monoalkyl ether and mineral acid are 10 to 30% by weight, 25 to 55% by weight and 5 to 10% by weight, and the balance is water, and The water content is at least 15% by weight, and the total of gamma-butyrolactone and ethylene glycol monoalkyl ether is 4%.
The detergent according to any one of claims 1 to 4, which is 0 to 70% by weight. 6. The method according to claim 1, wherein a surfactant is added.
The detergent according to any one of 1. 7. The detergent according to claim 6, wherein the surfactant is a surfactant containing sodium alkylbenzene sulfonate. 8. The method according to claim 6, wherein 1 to 5 parts by weight of the surfactant is added to 100 parts by weight of the detergent according to any one of claims 1 to 5. Detergent. 9. The cleaning agent according to claim 1, wherein the metal structure having a coating film on its surface is immersed in the detergent to peel off the coating film on the surface of the metal structure. Cleaning method to be. 10. The cleaning method according to claim 9, wherein the coating film is formed by a clear lacquer. 11. The cleaning method according to claim 9, wherein the metal structure is an aluminum sash. 12. The cleaning method according to claim 9, wherein the temperature of the cleaning agent is 35 to 65 ° C. 13. A metal structure having a coating film on its surface is dipped in the cleaning agent according to any one of claims 1 to 8, and then the metal structure is washed in a washing tank. The cleaning method according to any one of claims 9 to 12, wherein the body is washed with water, and the washing liquid in the washing treatment tank is circulated to the cleaning treatment tank and reused.