JPH05171076A - Paint remover - Google Patents

Abstract

PURPOSE:To obtain a solvent-based, strongly alkaline paint remover which can remove a coating film at room temperature by mixing dichloromethane with an aprotic polar solvent, a monoalcohol and an alcoholate. CONSTITUTION:The title remover comprises 70-95wt.%, based on the entire remover, dichloromethane, 1-15wt.% aprotic polar solvent of a dielectric constant of 30 (F/m), 1-15wt.% 1-4 C saturated or unsaturated monoalcohol and 1-15wt.% alcoholate of the general formula: R-OX (wherein R is 1-4 C alkyl; and X is an alkali metal).

Description

Detailed Description of the Invention

[0001]

The present invention relates to urethane, acrylic,
The present invention relates to a paint remover for resin paints such as epoxy and melamine.

[0002]

2. Description of the Related Art Currently, urethane, acrylic, epoxy,
The release agent for resin-based paints such as melamine is a solvent type release agent which is mainly composed of a halogenated hydrocarbon and an accelerator such as alcohol, formic acid (or amines), or caustic alkali. An aqueous solution type release agent obtained by adding a promoter such as polyhydric alcohol to the alkaline aqueous solution is used. The former solvent-type release agent is usually used at room temperature, and generally has a function of swelling the coating material and removing it from the substrate. Therefore, if the object to be coated has a complicated shape with severe irregularities, or if the surface of the base material is not smooth or if the coating film is very thin, it is not peeled off efficiently and brushing etc. as a post-treatment. There is a problem that the work of is required. On the other hand, when the latter aqueous solution type release agent is used, the coating film is dissolved and removed, but since the use temperature is as high as 80 ° C. or higher, it is not only dangerous for the work but also the base material. There is a problem that thermal deformation and thermal deterioration of the occur.

[0003]

In order to solve the above-mentioned problems, a solvent-type strong alkaline stripping agent, and
We have developed a release agent that dissolves the coating film at room temperature and has excellent removal performance of the coating film and does not require post-treatment such as brushing.

[0004]

According to the present invention, (a) dichloromethane is used in an amount of 70 to 95% by weight based on the total amount of the paint stripping agent, and (b) an aprotic polar substance having a dielectric constant of 30 (F / m) or more. 1 to 15% by weight of solvent, (c) saturated carbon number of 1 to 4,
Alternatively, 1 to 15% by weight of an unsaturated monohydric alcohol, and (d) R of the alcoholate represented by the general formula (1): R-OX (1) represents an alkyl group having 1 to 4 carbon atoms. X represents an alkali metal. The present invention provides a paint remover comprising 1 to 15% by weight of an alcoholate represented by the formula (1).

Dichloromethane, which is a component of the paint stripping agent of the present invention, is the main agent and quickly penetrates into the coating film to soften and swell the resin. The aprotic polar solvent has a dielectric constant of 30.
(F / m) or more, which has a synergistic effect with the counter ion of the alcoholate represented by the general formula (1), enhances the effect of the alcoholate, and has the effect of stably dissolving a high concentration of the alcoholate. When the amount of alcoholate is small, the alcoholate can be dissolved only with a monohydric alcohol, but the amount of alcoholate is limited, and once dissolved, the alcoholate is easily affected by the external environment such as water and easily. To deposit. However, by adding an aprotic polar solvent, the amount of alcoholate dissolved increases, the dissolved alcoholate becomes stable, and precipitation due to changes in the external environment is almost avoided. That is, the aprotic polar solvent has an effect of stably dissolving alcohol and alcohol in a high concentration in a dichloromethane solvent, and the coating film can be dissolved and peeled at room temperature. Examples include 1-3-dimethyl-2-imidazolidinone (DMI), dimethyl sulfoxide (DMS).
O), hexamethylphosphoric triamide (HMPA), sulfolane and the like. The amount used is 1 to 15% by weight, preferably 5 to 15% by weight, based on the total weight of the release agent. Blending in excess of 15% by weight is not suitable because it lowers the permeability of dichloromethane into the coating film.

The monohydric alcohol referred to in the present invention has 1 carbon atom.
It may be saturated or unsaturated in a range of ~ 4. For example, methanol, ethanol, n-propanol, isopropanol,
Examples include n-butanol, tert-butanol, allyl alcohol and the like. Two or more kinds of the alcohols may be mixed and used. The alcohols promote the permeation of dichloromethane into the coating film and are also effective as a stabilizer of alcoholate. The amount used is 1 to the total amount of the release agent.
It is 15% by weight, preferably 5 to 15% by weight. If the amount exceeds 15% by weight, the release agent itself has a flash point, and therefore it is better not to exceed 15% by weight for safety. On the other hand, if it is 1% or less, the solubility of alcoholate is poor and the permeability of dichloromethane into the coating film is poor.

R in the alcoholate represented by the general formula (1): R-OX (1) is an alkyl group having 1 to 4 carbon atoms or an alkenyl group. X is an alkali metal, and sodium and potassium are particularly preferable. For example,
Examples thereof include sodium methylate, potassium methylate, sodium ethylate, potassium butyrate and potassium ethylate. The alcoholate is a strong alkali and has a function of decomposing / dissolving the resin. The amount used is 1 to 15% by weight based on the total amount of the release agent. Preferably 5
10 to 10% by weight. The use of 15% by weight or more is not preferable because the amount of the aprotic polar solvent or alcohol necessary for stable dissolution increases and defects such as flammability and peelability occur.

According to the present invention, if desired, a paraffin wax as an evaporation inhibitor, a thickener, etc. may be added to the paint stripping agent. It is also possible to use methyl cellulose, acetate cellulose, hydroxyethyl cellulose or the like as a thickening agent to prepare a release agent for brush application.

[0009]

The effect of the well penetrating dichloromethane and the lower monohydric alcohol is that the paint swells and softens. Next, the resin is dissolved by the alcoholate whose effect is further promoted by the action of the aprotic polar solvent. Therefore, it became possible to carry out dissolution peeling at room temperature, which was impossible with the conventional peeling agents.

[0010]

【Example】

Examples 1 to 3 The flash point, solution state, and peeling performance of the release agent prepared according to the formulation of Examples 1 to 3 shown in Table 1 were tested. It carried out similarly about Comparative Examples 1-5. The flash point of the release agent and the state of the solution are shown in Table 1. The results of the peel test are shown in Table 2.

Test method Flash point--Tag closed flash point measuring method (JIS K 2
265). State of solution --- Visual observation. Peeling test --- As an object to be peeled off, an iron plate which is polished and has irregularities (JIS G 3141 SPCC-SD)
A primer and then urethane resin paint were used. The object to be peeled was immersed in a peeling agent having the formulation shown in Table 1 at room temperature of 25 ° C., and the paint peeling time and its state were visually observed.

[0012]

[Table 1]

[0013]

[Table 2]

[0014]

EFFECTS OF THE INVENTION Unlike the solvent-type release agent which swells and removes various kinds of resin-based paints, the release agent for paints of the present invention can dissolve and remove the paint at room temperature and improve the removal performance. Became possible. Further, the stripping agent according to the present invention can be removed by its strong dissolving power even for the removal of the primer, which was hardly swelled by the usual solvent type stripping agent and was difficult to remove. Therefore, it can be effectively removed even when the object to be coated has a complicated shape with large irregularities or when the coating film is very thin. Furthermore, in the same way, compared to the aqueous solution type stripping agent that removes the paint by decomposing / dissolving the resin, it is possible to remove the paint at room temperature and the safety is
The paint can be removed without causing thermal deformation or thermal deterioration of the substrate.

Claims (1)

[Claims] 1. (a) 70 to 95% by weight of dichloromethane based on the total amount of the paint stripping agent, and (b) a dielectric constant of 30 (F).
/ M) or more aprotic polar solvent 1 to 15% by weight,
(C) 1 to 15% by weight of a saturated or unsaturated monohydric alcohol having 1 to 4 carbon atoms, and (d) general formula (1): R-OX (1) (wherein R represents the number of carbon atoms. 1 to 4 alkyl groups are shown.
Indicates an alkali metal. ) A paint remover comprising 1 to 15% by weight of an alcoholate represented by the formula (1).