JPH11246801A - Coating film peeling agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the exhibition of excellent workability without using a chloride organic solvent and excellent peeling function in a coating film peeling agent for peeling the coating film formed on the surface of a metal material. SOLUTION: This coating film peeling agent contains at least >=0.1 wt.% of naphthalene. Further, the coating film peeling agent preferably contains a solvent compatible with naphthalene, water in the range from >=0 to <=20 wt.% or the like. Further, the agent may be optionally compounded with an acid, an amine, one of various surfactants, an evaporation suppressing agent, a thickener, a chelating agent or the like. When a metal product having a coating film is dipped in the coating film peeling agent, the coating film is peeled in a relatively short time. This makes it possible to dispense with the use of a chloride organic solvent such as methylene chloride, to increase workability when it is handled and to reduce ill effects on the environments.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paint remover, and more particularly, to a paint remover for removing a paint film formed on the surface of a metal substrate such as iron, brass or aluminum. It is about.

[0002]

2. Description of the Related Art Conventionally, many metal products are formed by forming a coating film on the surface of a metal substrate. In such products, in the case of repainting defective paint, changing the color, etc., or when the coating film adhered to the metal jig becomes a predetermined thick film due to repetition of coating,
It becomes necessary to peel the cured coating film from the substrate surface.

[0003] The thus-cured coating film is extremely strong because the molecules are three-dimensionally linked by crosslinking. In order to peel off such a strong coating film, a coating film peeling agent having a chlorine-based organic solvent such as methylene chloride as a main component has been generally employed (for example, JP-A-5-171076).

[0004] By the way, in the above-mentioned coating film release agent,
Since methylene chloride and the like were the main agents, there was a need to worry about the impact on the environment. Therefore, it is a fact that the user's intention to restrict the use of the chlorinated organic solvent such as the methylene chloride is increasing.

[0005] As described above, as a method of peeling a coating film without using methylene chloride or the like, a method of projecting a blast material onto the surface of the coating film, a method of mixing a mixture of caustic alkali and a diethylene glycol solvent at 80 ° C or more And a method of immersing a coated product in concentrated sulfuric acid at a high temperature.

[0006] However, the blasting method described above has a low work efficiency, and the method of immersing it in a mixed solution of caustic alkali or the like causes a metal base material to be significantly etched. In addition, the method of immersing in concentrated sulfuric acid has a problem in terms of work safety. For these reasons, none of the above methods can be said to be methods that should be actively adopted.

On the other hand, Japanese Patent Application Laid-Open No. 5-78608 discloses a method for removing a coating film using a coating film remover comprising a system containing an ester of benzyl (or methylbenzyl) alcohol and the same alcohol and formic acid. ing.

[0008]

In the technique disclosed in the above-mentioned publication, although a chlorine-based organic solvent such as methylene chloride does not need to be used, the effect of peeling off the coating film has not been sufficient yet. . That is, it took a considerable time to completely remove the coating film formed on the surface of the metal substrate.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a coating film remover for peeling a coating film formed on the surface of a metal substrate, comprising a chlorine-based organic solvent. An object of the present invention is to provide a coating film release agent which is excellent in workability without using a film and can exhibit excellent release performance.

[0010]

The inventor of the present invention has made intensive studies to solve the above-mentioned problems, and has completed the present invention. That is, among the present invention, in particular, in the invention according to claim 1, a coating film peeling agent for peeling a coating film formed on the surface of a metal base material, at least 0.1% by weight or more The main point is that it contains naphthalene. Here, at least 0.1% by weight or more means that the naphthalene content in the coating film release agent is 0.1% or more.
1% by weight or more and 100% by weight or less.

[0011] In the invention according to the second aspect, in the coating film remover according to the first aspect, the content of the naphthalene is at least 0.1% by weight and less than 30% by weight. I have.

Further, the invention according to claim 3 has the gist that the coating film release agent according to claim 1 or 2 contains a solvent compatible with the naphthalene.

[0013] In addition, according to the invention of claim 4, the gist of the invention is that the coating film release agent of claim 3 further contains more than 0% by weight and not more than 20% by weight of water. And

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the coating film remover of the present invention will be described in detail. The coating film remover of the present embodiment can be applied to various resin-based paints (coating films) such as urethane, acrylic, epoxy, and melamine. In particular, naphthalene, which is an essential component of the coating film peeling agent, quickly penetrates into the coating film to soften or swell the resin. In addition, this coating film release agent, acidic, neutral,
Of the alkaline properties, any property may be used, and it can be appropriately used depending on the application.

The content of the naphthalene must be at least 0.1 (% by weight) or more. Here, at least 0.1 (wt%) or more means that the naphthalene content in the coating film release agent is 0.1 (wt%) or more and 100 (wt%) or more.
(% By weight) or less. If the content is less than 0.1% by weight, the effect of quickly peeling off the coating film cannot be expected.

It is desirable that the content of naphthalene is not less than 0.1 (% by weight) and less than 30 (% by weight).
When the content of naphthalene is 30 (% by weight) or more, the effect of peeling the coating film can be expected, but it is necessary to consider the environment such as ventilation. In addition, there is a concern that the nature of naphthalene having a relatively high melting point may cause the coating film release agent to solidify at room temperature. A more desirable content is 1 (% by weight) or more and 20 (% by weight) or less, and still more preferably 10 (% by weight) or more and 15 (% by weight) or less.

Further, it is desirable that the coating film release agent contains a solvent compatible with naphthalene. Examples of compatible solvents include, for example, N-methyl-2-pyrrolidone, benzyl alcohol, γ-butyrolactone, diethylene glycol, diethyl ether, diethylene glycol monobutyl ether, and other solvents generally known as non-methylene chloride solvents. Mainly mentioned. By containing such a solvent, it is possible to prevent the coating film release agent from solidifying at room temperature.

In addition, the coating film release agent desirably contains more than 0 (weight%) and not more than 20 (weight%) water. More desirable content is 10 (% by weight) or more 2
0 (% by weight) or less. Thereby, the flammability of the coating film release agent can be reduced, and the workability can be improved. Further, since the dissolution of the coating film in the release agent is suppressed as much as possible, an increase in the use cycle of the coating film release agent can be expected, and long-term use is possible.

If necessary, acids such as formic acid, acetic acid and propionic acid, amines such as monoethanolamine, various surfactants (eg dodecylbenzenesulfonic acid), liquid paraffin And the like, a thickener such as methylcellulose and hydroxyethylcellulose, a chelating agent such as EDTA for preventing discoloration of the base material, and the like. In this case, they may be used alone or in combination.

Now, the coating film release agent constituted as described above is used by a known method. That is, a coating film is released from the surface of a metal substrate by filling a container with a coating film release agent and immersing a metal product or the like having the coating film in the container. At this time, the coating film release agent was changed to 4
It is desirable to use it after heating it to 0 (° C.) or more in order to shorten the peeling time. A more desirable temperature is 70
(° C.) or more, and particularly when the naphthalene content in the coating film release agent is 100 (% by weight), the temperature is 80 (° C.).
More desirably.

The metal substrate from which the coating film has been peeled off through the immersion step is subjected to a water washing step. This water washing is performed for the purpose of removing the coating film remover adhering to the surface of the metal substrate and removing the coating film that has been peeled off but remains on the substrate surface.
Generally, in the water washing step, a jet water having a predetermined pressure is sprayed on the substrate surface. At this time, the coating film remover that has adhered to the substrate surface is easily and reliably removed in the water washing step. In addition, as for the treatment of the water containing naphthalene used for washing, the known drainage technology can sufficiently cope with the current drainage regulation, and does not impose a great burden on the economy.

Further, the coating film remover of the present embodiment is applied to a metal base material such as iron, brass, or aluminum having a coating film formed on the surface thereof. The coating film is generally one that has gone through a series of coating film forming steps such as painting and baking hardening by an ordinary method. Further, the coating film may be composed of a primer layer and an overcoat film layer in addition to the case where the coating film is composed of only one layer.

The paint used to form the coating film is not particularly limited, and examples thereof include various paints such as urethane resin, acrylic resin, epoxy resin, and melamine resin.

According to the coating film remover of the present embodiment described in detail above, the following effects can be obtained. (1) According to the coating film remover of the present embodiment, when removing the coating film formed on the surface of the metal substrate, the coating film remover can be used without using a chlorine-based organic solvent as in the related art. Since naphthalene is contained at least 0.1 (% by weight) or more, excellent workability and excellent peeling performance can be exhibited.

(2) According to the coating film release agent of the present embodiment, by setting the naphthalene content in the coating film release agent to 0.1% by weight or more and less than 30% by weight, 1)
The effect described in (1) can be further ensured. Further, it is possible to eliminate the concern that the coating film peeling agent solidifies at room temperature.

(3) According to the coating film release agent of the present embodiment, since the coating film release agent contains a solvent compatible with naphthalene, the coating film release agent solidifies at room temperature. Can be avoided.

(4) According to the coating film release agent of the present embodiment, the coating film release agent contains more than 0 (% by weight) and not more than 20 (% by weight) of water, thereby removing the coating film. The flammability of the agent can be reduced, and the workability can be improved. In addition, since the dissolution of the coating film in the release agent is suppressed as much as possible, an increase in the use cycle of the coating film release agent can be expected, and it can be used for a long time.

(5) According to the coating film release agent of the present embodiment, an acid, an amine, various surfactants, an evaporation inhibitor, a thickening agent, a chelating agent and the like are contained in the coating film release agent. The effects described in the above (1) to (4) can be further ensured by appropriately mixing them.

[0029]

Next, the embodiments will be described more specifically with reference to examples, but the embodiments are not limited to these examples.

Examples 1 to 6 Examples 1 to 6 include:
Naphthalene as a main agent is 1 to 100 (wt%), as a solvent compatible with naphthalene, N-methyl-2-pyrrolidone is as 0 to 64 (wt%), as amines (solvent compatible with naphthalene) , Monoethanolamine to 0
１５15 (% by weight) and six types of coating film release agents having water of 0 to 20 (% by weight) were prepared. Each container was filled with the paint remover, the temperature was set to 70 (° C.), and the S-shaped iron coating jig was immersed in the paint remover and held for 4 (hours). As the S-shaped iron coating jig, a melamine resin-based coating is applied to an S-shaped iron jig having a total length of 50 (mm), and the coating is baked and cured to a thickness of 1 to 1.
One having a coating film of 2 (mm) was used.

Comparative Example 1 Comparative Example 1 contains no naphthalene at all and contains N-methyl-2-pyrrolidone at 65%.
(% By weight), 15 (% by weight) of monoethanolamine,
One type of coating film release agent having water (20% by weight) was prepared. Then, each of the coating film release agents is filled in the container, the temperature is set to 70 (° C.) as in Examples 1 to 6, and the same S-shape as in Examples 1 to 6 is contained in the coating film release agent. The iron coating jig was immersed and held for 4 (hours).

At this time, the peeling state of the coating film (visual observation) and the insolubility of the coating film with respect to each coating film releasing agent were examined.
Separately, the solidification state of each coating film release agent at room temperature was examined, and the results are shown in Table 1. In the peeled state in the table,
◎ indicates that the coating was completely peeled off (100% peeled off), ○ indicates that the coating was almost completely peeled off (90% peeled off), and x indicates that the coating remained partially (90
%). In addition, in the insolubility of the coating film in the table, ◎ indicates that the coating film did not dissolve at all in the coating release agent, and ○ indicates that the coating film was slightly dissolved in the coating release agent. Indicates that the coating film was slightly dissolved in the coating film release agent. Further, in the solidification state at room temperature in the table, ○ indicates that the coating film release agent did not solidify, and Δ indicates that some of the coating film release agents solidified.

[0033]

[Table 1] As shown in Table 1 above, according to the coating film removers of Examples 1 to 6, the coating film on the surface of the S-shaped iron coating jig was completely completed without using a chlorine-based organic solvent conventionally used generally. Or it is in a state where it is almost completely peeled off, and it is understood that it has extremely excellent peeling performance. In other words, if naphthalene is contained in the coating film release agent, the desired excellent release performance will be exhibited extremely well. In addition, since a chlorine-based organic solvent is not used, adverse effects on the environment can be suppressed, and at the same time, workability in handling can be improved and equipment costs can be reduced.

On the other hand, in the case where no naphthalene is contained in the coating film release agent as in Comparative Example 1, the coating film partially remains on the surface of the S-shaped iron coating jig. It can be seen that the peeling performance of the sample was inferior.

As shown in Table 1, Examples 5 and 6
Film-stripping agents, ie, those containing no water and having a naphthalene content of 30 and 100 (% by weight) are slightly soluble in the insolubility of the coating film and in the solidified state at room temperature. Although there is a problem, it can be seen that the desired peeling performance is sufficiently exhibited in the peeled state. (Examples 7 to 9) In Examples 7 to 9, naphthalene as a main agent was 0.1 to 15 (% by weight), and benzyl alcohol was 75 to 8 as a solvent compatible with naphthalene.
9.9 (% by weight), and three kinds of coating film release agents having 10 (% by weight) of dodecylbenzenesulfonic acid as a surfactant were prepared. Each container was filled with the coating film release agent, the temperature was set to 70 (° C.), and the test piece was immersed in the coating film release agent. As a test piece, an acrylic resin-based paint was applied to a brass base material of 60 (mm) × 100 (mm) × 1 (mm) to have a thickness of 15 mm.
(Μm) was used. Comparative Example 2 As Comparative Example 2, 90% (by weight) of benzyl alcohol was used as a solvent containing no naphthalene and compatible with naphthalene, and 10% (weight%) of dodecylbenzenesulfonic acid was used as a surfactant. ) Was prepared. Then, each of the coating film release agents is filled in a container, and the temperature is set to 70 as in the above Examples 7 to 9.
(° C.) and the same test piece as in Examples 7 to 9 was immersed in the coating film release agent.

Table 2 shows the results of examining the peeling time (min) of the coating film at that time.

[0037]

[Table 2] As shown in Table 2 above, according to the coating film removers of Examples 7 to 9, the peeling time of the coating film on the test piece was relatively short without using a chlorine-based organic solvent conventionally used generally. It can be seen that it has extremely excellent peeling performance. In other words, if at least 0.1 (% by weight) or more of naphthalene is contained in the coating film release agent,
The workability at the time of peeling is excellent, and the desired excellent peeling performance is extremely excellently exhibited.

On the other hand, the film release agent containing no naphthalene at all as in Comparative Example 2 was compared with those of Examples 7 to 9 containing naphthalene, It can be seen that the time required for the peeling of the film was extremely long, and the peeling performance of the coating film was poor.

Further, technical ideas that are not described in the claims and that can be grasped from the embodiment or the examples are described below together with their effects.

(A) The coating film release agent according to claim 3 or 4, further comprising a surfactant. With such a configuration, the effect of the invention described in claim 3 or 4 can be further ensured.

[0041]

As described in detail above, according to the present invention,
It has the following excellent effects. According to the invention as set forth in claim 1, in a coating film remover for peeling a coating film formed on the surface of a metal base, excellent workability without using a chlorine-based organic solvent, and excellent An unprecedented outstanding effect of exhibiting peeling performance is exhibited.

According to the invention described in claim 2, according to claim 1
Can be more reliably achieved. According to the third aspect of the invention, in addition to the effects of the first or second aspect of the invention, it is possible to prevent the coating film release agent from solidifying at room temperature.

According to the invention described in claim 4, according to claim 3,
In addition to the effects of the invention described in (1), the flammability of the coating film release agent can be reduced, and the workability can be further improved.

Claims (4)

[Claims] 1. A coating film remover for removing a coating film formed on the surface of a metal substrate, comprising at least 0.1% by weight or more of naphthalene. Film release agent. 2. The coating film remover according to claim 1, wherein the content of the naphthalene is 0.1% by weight or more and less than 30% by weight. 3. The coating film stripping agent according to claim 1, further comprising a solvent compatible with the naphthalene. 4. The film-stripping agent according to claim 3, further comprising more than 0% by weight and not more than 20% by weight of water.