JPH10292138A - Composition for peeling off coated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition having excellent coated film peeling-off force, sustaining stable peel-off property for a long period of time, and having high safety, by dissolving aromatic alcohols, glycols and an alkali metal hydroxide in water. SOLUTION: This composition as an aqueous solution is obtained by dissolving (A) 1-60 wt.% of aromatic alcohols (e.g. benzyl alcohol), (B) 1-70 wt.% of glycols (e.g. propylene glycol) and (C) 1-48 wt.% of an alkali metal hydroxide (e.g. caustic potash), and (D) 1-30 wt.% of glycol ethers (e.g. diethylene glycol monobutyl ether) and (E) a chelating agent, a surfactant, a rust preventive, a viscosity controller and a coloring agent, etc., as necessary, in water. To peel off a coated film by using the composition, bringing the composition into contact with the coated film as the object of peel-off and holding until the coated film can be naturally peeled off or becomes to a state of readily removable by brushing, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating film removing composition and a coating film removing method.

[0002]

2. Description of the Related Art A large amount of paint adheres to various tools for painting, for example, jigs, hangers, nets, snowboards, masking jigs, etc. at the time of painting. Need to be removed. In addition, it is necessary to remove an unnecessary portion of the coating film and a coating film of a defective coating product on the object to be coated.

[0003] As a method of peeling off unnecessary coating films,
As a method using an inorganic release agent, a method in which a high-concentration caustic soda aqueous solution is boiled and used, a method in which an aqueous solution obtained by adding a chelating agent and a surfactant to caustic soda at a high temperature, and a solvent such as alcohol added to caustic soda are used. A method of using an aqueous solution at a high temperature is known. However,
All of these methods have a problem in safety because a high-concentration alkaline aqueous solution is used at a high temperature, and furthermore,
It is economically disadvantageous because of the high cost of heating. Further, when a coating film having high alkali resistance is peeled, a long processing time is required, and it is difficult to completely remove the coating film.

[0004] A release agent comprising an aqueous solution containing a lower monohydric alcohol and an aprotic polar solvent is also known (Japanese Patent Application Laid-Open No. 2-274775). However, there is a problem in the stability of the performance, and also a problem in the working environment due to the generated odor. In addition, a release agent in which an alkali compound such as an alkali metal hydroxide or an alkaline earth metal hydroxide is added to N-methyl-2-pyrrolidone, if necessary, in an amount of about 100 to 5000 ppm is also known (Japanese Unexamined Patent Application Publication No. 5-27960
No. 7), the cost is high because N-methyl-pyrrolidone is very expensive, and the low concentration of the alkali compound absorbs carbon dioxide in the air during use to rapidly reduce these components. However, there is a problem that carbonation causes a decrease in peeling force.

Also, caustic soda or caustic potash 50-70
Aqueous solution containing 0 to 20% by weight of an organic amine such as alkanolamine, 5 to 20% by weight of a high boiling point solvent such as glycol ether, an organic acid such as gluconic acid or a salt thereof, and a surfactant. There is also known a method of peeling a coating film by heating the film (JP-A-60-23587).
No. 3), this method is effective for relatively many types of coating films, and the components used are non-dangerous in terms of legal regulations.
In addition, it does not cause corrosion of iron, which is often used as a material of an object to be peeled, and is suitable for mass processing of a large and complicated object to be peeled or a large heavy object. There are advantages. However, in this method, depending on the thickness and type of the coating film, it takes several hours to several days to peel off, and it is desired to peel off the coating film more efficiently from an industrial and economic viewpoint. In addition, from the viewpoint of safety and economy, a release agent having a lower concentration of an alkali metal hydroxide is demanded, and furthermore, the active ingredient is hardly volatilized, and the stability of the release performance is good. There is also a great demand for release agents that do not have any adverse effects.

[0006]

SUMMARY OF THE INVENTION The main object of the present invention is to:
An object of the present invention is to provide a coating film peeling composition having excellent film peeling force, high safety, and stable and long-lasting peeling performance.

[0007]

The inventor of the present invention has conducted intensive studies in view of the above-mentioned problems in the prior art, and has found that aromatic alcohols, glycols, and alkali metal hydroxides as essential components. The coating film remover composed of an aqueous solution contains a very excellent coating film peeling action that cannot be obtained with an aqueous solution containing these components alone or an aqueous solution containing any combination of two components, and Compared to conventional inorganic release agents, the alkali metal hydroxide can be made lower in concentration, so safety is high. Also, since the components are hard to volatilize, there is little change in composition and the working environment is deteriorated. I found that there was little to do. Further, it was found that the peeling performance was further improved by adding a glycol ether to this aqueous solution, and the present invention was completed here.

That is, the present invention provides a composition for removing a coating film comprising an aqueous solution containing an aromatic alcohol, a glycol and an alkali metal hydroxide, and a coating composition for removing a coating film further containing a glycol ether. It provides a composition.

The present invention also provides a method for peeling a coating film, which comprises contacting the above-mentioned composition for peeling a coating film with a coating film.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Specific examples of aromatic alcohols that can be used in the composition for removing a coating film of the present invention include benzyl alcohol, 4-methylbenzyl alcohol, 2-ethylbenzyl alcohol, phenethyl alcohol and the like. These can be used alone or in combination of two or more. Of these, benzyl alcohol is inexpensive and suitable from the viewpoint of environmental health.

Specific examples of glycols include ethylene glycol, propylene glycol, butylene glycol, butanediol, diethylene glycol, dipropylene glycol, triethylene glycol, glycerin and the like. These may be used alone or in combination of two or more. Can be blended. Of these, propylene glycol is preferred from the viewpoint of environmental health.

As the alkali metal hydroxide, lithium hydroxide, caustic soda, caustic potash and the like can be used.
These can be used alone or in combination of two or more. Of these, caustic potash is preferred because of its good solubility in organic solvents.

The concentration of each of the above components in an aqueous solution is about 1 to 60% by weight of aromatic alcohols (hereinafter simply referred to as "%"), preferably about 2 to 8%,
It may be about 70%, preferably about 2 to 50%, about 1 to 48% of an alkali metal hydroxide, preferably about 2 to 40%.

The composition for removing a coating film of the present invention is an aqueous solution containing the above-mentioned components. In the composition, the order in which the components are mixed is arbitrary. In addition to using the components as an aqueous solution in which the components are mixed in advance, the components can be mixed immediately before use and used as an aqueous solution. These aqueous solutions are generally used as a homogeneous solution, but can also be used in an emulsion or a non-uniform state.

The release composition having the above composition has a smaller amount of the alkali component than the conventional inorganic release agent.
It is highly safe, has a better release force than conventional release agents, and can release a coating film in a short time. Furthermore,
Since the organic solvent used is low in volatility, it has excellent characteristics that the composition does not fluctuate and the working environment is hardly deteriorated.

In the stripping composition of the present invention, the peeling force can be further improved by blending a glycol ether in addition to the above three components. Examples of glycol ethers include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, 2- (methoxymethoxy) ethanol, 2- (hexyloxy) ethanol, -Ethylene glycol ethers such as phenoxyethanol; diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol ethers such as diethylene glycol monobutyl ether; triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monopropyl Ether, triethylene glycol Triethylene glycol ethers such as nobutyl ether; propylene glycol ethers such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether and propylene glycol monobutyl ether; dipropylene glycol monomethyl ether and dipropylene glycol monoethyl Dipropylene glycol ethers such as ether, dipropylene glycol monopropyl ether and dipropylene glycol monobutyl ether; butylene glycol ethers such as butylene glycol monomethyl ether, butylene glycol monoethyl ether, butylene glycol monopropyl ether and butylene glycol monobutyl ether; Can be used It can be formulated by mixing them alone or two or more. Among them, diethylene glycol monobutyl ether is preferred from the viewpoint of low volatility and environmental health.

The amount of the glycol ether is preferably about 1 to 30% in the composition of the present invention,
More preferably, it is about 10% to 10%.

The composition of the present invention may further comprise, if necessary,
Various chelating agents, surfactants, rust inhibitors, viscosity modifiers, coloring agents, and the like, which are blended in the conventional coating film peeling composition, can be appropriately added.

To peel off the coating film using the composition of the present invention, the coating film of the present invention is brought into contact with the coating film to be peeled, and then the coating film is peeled off naturally or by brushing or the like. It may be left until it can be easily peeled off. The method of bringing the composition of the present invention into contact with the coating film is not particularly limited, and the composition of the present invention may be brought into contact with the coating film to be peeled by a method such as dipping, coating, spraying, or showering. As a treatment condition, the contact may be performed in the atmosphere at room temperature or under heating, and the heating can promote peeling. The heating temperature is
The temperature may be lower than the boiling point of the composition of the present invention.
The temperature may be about 95 ° C. or lower. The contact time is not uniform depending on the concentration of each component, the processing temperature, the thickness of the coating film, the type, the history, the coating method, and the like, but may be generally about 10 minutes to 2 hours. In order to further shorten the stripping time, the composition of the present invention may be physically moved by a method such as stirring or the object to be stripped may be rocked in the composition.

By leaving the composition of the present invention in contact with the coating film and leaving it to stand according to the various methods described above,
Phenomena such as dissolution, swelling, and deterioration occur, and the coating film comes off spontaneously, or becomes in a state where it can be easily removed by brushing or the like.

Next, if necessary, the coating film may be removed by brushing or the like, and then washed with water or the like.

The type of the coating film to be peeled off by the composition of the present invention is not particularly limited.
Processes coatings formed from various commonly used paints such as epoxy paints, polyester paints, melamine paints, urethane paints, alkyd paints, urea paints, silicon resin paints, lacquer paints, and mixtures of these paints Can be targeted. Further, a coating film treated with a primer or a plasma may be used, or a coating film obtained by stacking a plurality of coating films may be used. Further, the coating film may contain aluminum, zinc, tin, other metals, and the like. At the time of peeling, metals such as aluminum and zinc react with the alkali metal hydroxide in the peeling agent. Can also be used as a method for removing.

The type of the object to be peeled is not particularly limited. For example, materials in various fields such as precision parts such as electronics and watches, electric products, automobile parts, airplane parts, and polymer parts may be used. it can. Furthermore, coating tools such as jigs, hangers, nets, snowboards, and masking jigs used at the time of coating can also be processed. Also, there is no particular limitation on the material of the material, and materials made of various metals, plastics, ceramics, wood, and the like can be used as the processing object. Must be avoided.

[0024]

The composition for peeling a coating film of the present invention has a very excellent coating film peeling action, and can peel a coating film in a shorter time than when a conventional peeling agent is used. Can be. In addition, the alkali metal hydroxide can be made lower in concentration than the conventional inorganic release agent, so that the safety is also good. Furthermore, since the volatility of the organic solvent used is low, the composition does not fluctuate much, the peeling performance can be maintained for a long time, and the working environment is hardly deteriorated.

[0025]

The present invention will be described in more detail with reference to the following examples.

Example 1 According to each of the following formulations, each of the components was dissolved in water to prepare each of the release compositions.

Invention product 1 Flaky caustic potash 24.0% Benzyl alcohol 5.0% Propylene glycol 23.0% Sodium monophosphate (rust inhibitor) 1.0% Sodium gluconate (chelating agent, rust inhibitor) 1.5% Sodium carbonate (rust inhibitor) 1.0% Nonionic surfactant 0.1% Water 44.4% Invention product 2 Flaky caustic potash 24.0% Diethylene glycol monobutyl ether 5% Benzyl alcohol 2.5% Propylene glycol 23.0% Sodium primary phosphate (rust inhibitor) 1.0% Sodium gluconate (chelating agent, rust inhibitor) 1.5% Sodium carbonate (rust inhibitor) 1.0% Nonionic surfactant 0.1% Water 44.4% Comparative product 1 Flaky caustic potash 24.0% Diethylene glycol monobutyl ether 5.7% Sodium phosphate monobasic (Rust inhibitor) 1.0% Sodium gluconate (chelating agent, rust inhibitor) 1.5% Sodium carbonate (rust inhibitor) 1.0% Nonionic surfactant 0.1% Water 66.7% Comparative product 2 Flaky caustic potash 24.0% Benzyl alcohol 5.0% Sodium primary phosphate (rust inhibitor) 1.0% Sodium gluconate (chelating agent, rust inhibitor) 1.5% Sodium carbonate (rust prevention) 1.0% Nonionic surfactant 0.1% Water 67.4% Comparative product 3 Flaky caustic potash 24.0% Propylene glycol 23.0% Sodium monophosphate (rust inhibitor) 1.0 % Sodium gluconate (chelating agent, rust inhibitor) 1.5% Sodium carbonate (rust inhibitor) 1.0% Nonionic surfactant 0.1% Water 49.4% Comparative product 4 Flaky cargo 24.0% diethylene glycol monobutyl ether 2.5 Benzyl alcohol 2.5% Sodium monophosphate (rust inhibitor) 1.0% Sodium gluconate (chelating agent, rust inhibitor) 1.5% Sodium carbonate (rust inhibitor) 1.0% Nonionic interface Activator 0.1% Water 67.4% As a test piece, a sample (test piece 1) in which an epoxy resin was baked at 180 ° C. on an iron plate to form a 60 μm thick coating film, and an epoxy-melamine resin was formed on the iron plate. Using a sample (test piece 2) in which a coating film having a thickness of 120 μm was formed by baking at 160 ° C., the test piece was immersed in each of the peeling compositions maintained at a liquid temperature of 70 ° C. The state of the coating film was visually observed. Table 1 below shows the time until the coating film is peeled off.

Table 1 Peeling composition Time until the coating film is peeled Test piece 1 Test piece 2 Invention product 1 15 minutes 20 minutes Invention product 2 14 minutes 18 minutes Comparative product 1 No change after 60 minutes After 60 minutes No change Comparative product 2 No change after 60 minutes No change after 60 minutes Comparative product 3 No change after 60 minutes No change after 60 minutes Comparative product 4 No change after 60 minutes No change after 60 minutes As is clear from the above results, When the release agents of the present invention products 1 and 2 were used, the coating film was peeled off after 14 to 15 minutes in the test piece 1 and after 18 to 20 minutes in the test piece 2, whereas the comparative product 1 was used. When each of the release agents Nos. To 4 was used, no peeling of the coating film occurred even after 60 minutes had elapsed.
As is evident from the results, the composition for removing a coating film of the present invention has excellent release performance as compared with a conventional release agent.

Claims (3)

[Claims] A composition for removing a coating film comprising an aqueous solution containing an aromatic alcohol, a glycol and an alkali metal hydroxide. 2. The coating film peeling composition according to claim 1, further comprising a glycol ether. 3. A method for removing a coating film, comprising bringing the composition for removing a coating film according to claim 1 into contact with a coating film.