JP2910337B2 - Decomposition / removal agent for resin coating and method for decomposition / removal of resin coating - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION Paint removal agent and paint removal for resin parts with effective paint removal performance, good workability, and high environmental safety in the resin coating processing process or the pretreatment process for recycled materials. Law is required. The present invention relates to a resin film decomposition / removal agent which does not cause ozone layer destruction and the like and is excellent in handleability, and a method for decomposing and removing a resin film using the decomposition / removal agent.

[0002]

2. Description of the Related Art Conventional stripping agents for resin coatings include chloropentafluoropropane / 1,1-dichloro-1-trifluoroethane mixed solvent composition (JP-A-2-286795) and chloropentafluoropropane. A dichlorotrifluoroethane mixed solvent composition (JP-A-2-286796) and the like have been proposed. Further, the inventors have already prepared a resin coating film remover composition solution and a removing method (Japanese Patent Application No. 3-84643).
No.) provided a solvent or solution composition capable of physically or chemically removing a coating film. Further, ordinary halogen solvents such as methylene chloride, strong alkaline solutions or strong acid solutions are well known.

[0003]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Application Laid-Open No. 2-286795.
The mixed solvent compositions disclosed in Japanese Patent Application Laid-Open Nos. 2-286796 and 2002-286796 are excellent in detergency against oils and fats and have a low risk of destruction of the ozone layer. In addition, there are problems such as that the use is limited to the above, and that since the molecular chain contains a large number of halogen atoms (F, Cl), care must be taken for handling in terms of environmental hygiene. In addition, there is a problem that the use of a normal halogen-based solvent deteriorates environmental hygiene and also causes ozone layer destruction. The use of a strong alkaline solution or a strong acid solution also involves problems such as work safety and environmental safety, as well as complexity such as the necessity of a post-treatment step such as neutralization. Further, the mixed solvent composition described in the specification of Japanese Patent Application No. 3-84643 has a small solution wettability and solution permeability of the coating film resin,
Further, when thiocyanate is used, there is a problem that ion dissociation is small.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of such a conventional problem, and is directed to an alkali metal (group 1A), an alkaline earth metal (group 2A), or an alkali metal (group 2A).
Compound C consisting of quaternary ammonium thiocyanate
Compound D consisting of alcohols having a boiling point of 100 ° C. or less at normal pressure.
85% by weight, desirably 20-60% by weight, water 5-60% by weight,
It is preferable to spray or apply a resin coating decomposition / removing agent consisting of a mixture of three components of 10 to 30% by weight at 50 to 120 ° C., preferably 50 to 100 ° C. Alternatively, the above-described problem is solved by immersing the resin component in the decomposition remover.

The decomposition-removing agent for the resin coating film of the present invention contains 8 to 65% by weight of a compound C consisting of an alkali metal (group 1A) or alkaline earth metal (group 2A) or a quaternary ammonium thiocyanate. 10 to 85% by weight of a compound D consisting of alcohols having a boiling point of 100 ° C. or less at a pressure of 5 to 60%
It is characterized by being composed of three components by weight. As the compound C, thiocyanic acid represented by M (S = C = N) _{n wherein} M represents an alkali metal (group 1A) or an alkaline earth metal (group 2A), or a quaternary ammonium Salts are used. Examples of the compound D, the following formula R ₄ -OH monool [R ₄ in the formula is the CnH _2n + 1 indicating the (n = 1 to 10) or an aromatic group] represented by the following formula HO-R ₅ A diol represented by —OH wherein R ₅ represents CnH _2n (n = 2 to 10) or an aromatic group;

Embedded image Or the following equation

Embedded image A triol represented by the following formula

Embedded image [R ₆ in the formula is a tetraol represented by CnH _2n-1 (n = 4 to 5).

[0006]

The function of the compound C is to react with the coating resin or the primer resin and decompose and remove it. The metal thiocyanate of the compound C decomposes and removes the coating resin or the primer resin according to the following model reaction formula 4.

Embedded image

That is, the organic ion radical generated by the ion dissociation of the compound C and the alcohol component of the compound D selectively decompose the ether bond in the coating resin.

On the other hand, compound D, which is a solvent for compound C,
It is composed of alcohols such as mono, di, tri, tetraol having 1 to 4 hydroxyl groups. The action of compound D is to promote the solution wettability and solution permeability of the coating resin, ie, to swell the resin coating or primer to promote the diffusion / penetration of compound C;
Solvating ion radicals of compound C such as metal thiocyanate. Therefore, it is inconvenient that the carbon chain is too long like n-dodecanol because of high hydrophilicity, and the use limit is about 10 carbon chains.

The action of water, which is a direct solvent of the compound C, is to promote the diffusion / permeation of the compound C in the same manner as the action of the alcohols, and to promote the ionization of the compound C such as metal thiocyanate. In addition to solvation of radicals, improvement of solution wettability of coating resin and drastic increase of ion dissociation can be mentioned.

As described above, when the concentration of compound C is lower than 8% by weight, the coating resin or the primer resin cannot be sufficiently decomposed. On the other hand, it is practically impossible to increase the concentration of compound C above 65% by weight due to the problem of solubility in a solvent. On the other hand, when the concentration of water is as low as less than 10% by weight, sufficient ion dissociation cannot be performed, and decomposition and removal cannot be performed. On the other hand, if the concentration of water is higher than 60% by weight, the solution wettability and the diffusion / permeability of the coating resin are significantly reduced, and the compound C is solvated stably, thereby impairing the ability to remove and remove the coating. Next, if the concentration of alcohols is less than 10% by weight, the wettability of the coating resin and the diffusion / permeability of the coating resin are remarkably reduced, so that they cannot be used. On the other hand, when the concentration of the alcohols is more than 85% by weight, the solubility of the compound C is lowered, and the compound C is not solvated properly. The reaction temperature is 50
When the temperature is lower than 0 ° C., the compound D cannot swell the coating resin or the primer resin sufficiently, and the compound C cannot sufficiently diffuse / permeate the coating resin or the primer resin,
They cannot be disassembled. On the other hand, if the reaction temperature is higher than 100 ° C., the composition changes due to the evaporation of the solvent, and the operation becomes difficult, which makes it unsuitable for practical use.

[0011]

The present invention will be described below with reference to examples and comparative examples. Preparation Example of Resin-coated Decomposed Film Remover Composition Liquid The compounds C and D (liquid) and water were weighed by an automatic balance in a greenhouse at a predetermined weight, and the compound C was dissolved in the compound D in a beaker. At that time, the mixture was stirred using a magnetic stirrer and a stirrer, and in some cases, heated in a water bath or an oil bath to prepare a decomposition remover for the resin coating film.

Table 1 shows the results of the evaluation of the decomposition and removal of the resin coating film. In addition, industrially, it is also possible to prepare a decomposition remover for the resin coating by weighing the converted volume by using the density of the compound D.

[0013] a resin decomposed and removed Evaluation Test Examples of the coating film Next, an appropriate amount of degradation removing agent of the resin film (about 100ml) placed in a round-bottom flask magnetic stirrer stirring element,
Reflux until the set temperature (50-100 ° C) is reached. After maintaining the decomposition remover at a set temperature, five pieces of about 10 mm width × about 10 mm height × about 2 mm thickness cut out from the resin coating treated resin part are put into a flask, and the decomposition remover is used as the decomposition remover. It was immersed for 45 minutes, left for 15 minutes, and observed. Thereafter, the split pieces were removed from the flask, and the state of decomposition and removal of the resin coating was visually determined.

In the evaluation of decomposition and removal of the resin coating in Table 1,
Specific evaluation test examples are shown. The types of the resin-coated resins used in the evaluation test were two (I, II), and both had different chemical compositions of the coating resin and the primer resin. In Table 1,
After the evaluation test, when a change was observed in the coating resin and the primer resin, ◎ mark when the primer resin was decomposed, ○ mark when the coating resin was decomposed, partial dissolution or decomposition or swelling was observed In this case, the number of changes was indicated in a circle, and in the case of no change, the number of changes was indicated in a cross. (5 test samples each)

Example 1 About 100 parts of a decomposition remover (sodium thiocyanate / ethanol / water = 45% by weight / 22% by weight / 33% by weight) of a resin coating film
The mixture was placed in a 200 ml eggplant-shaped flask, stirred on a water bath using a magnetic stirrer, and refluxed until a predetermined temperature was reached. Next, resin painted parts (painting I, II)
5 pieces each (width × length × thickness = 10 × 10 × 2 mm) are cut out and immersed in a solution for decomposing and removing the resin coating in the flask,
Treated for 30 minutes. Thereafter, the contents of the flask were taken out into a beaker, and the resin coating of the split pieces and the degree of decomposition of the primer resin were visually checked. The results obtained are as shown in Table 1. Examples 2 to 14 and Comparative Examples 1 to 9 The decomposing and removing agents for the resin coatings of Examples 2 to 14 and Comparative Examples 1 to 9 shown in Table 1 were used, and the predetermined temperature was set to the temperature shown in Table 1 (water bath). Alternatively, the split pieces of the resin-coated part were treated in the same manner as in Example 1 except that the heating was performed in an oil bath, and the degree of decomposition of the coating resin and primer resin of each split piece was visually checked. The results obtained are as shown in Table 1.

[0016]

[Table 1]

[0017]

As described above, the resin film-decomposing / removing agent of the present invention comprises 8 to 65% by weight of compound C, 10 to 85% by weight of compound D and 5 to 60% by weight of water. As a result, at a temperature of 50 to 100 ° C., the decomposing / removing agent is sprayed or applied to the resin-coated parts, or immersed in the decomposing / removing agent, thereby deteriorating environmental hygiene and causing ozone layer destruction. Chemically decomposes only the coating resin without causing it and breaking the resin base material without the electrophilic site, solubilizing it in solution, and successfully and efficiently decomposing the resin coating The effect of being able to remove is obtained.

Continuation of the front page (56) References JP-A-4-293975 (JP, A) JP-A-5-93157 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C09D 9 / 00-9/04

Claims (2)

(57) [Claims] 1. An alkali metal (group 1A) or alkaline earth metal (group 2A) or quaternary ammonium thiocyanate 8 to 65% by weight, an alcohol having a boiling point of 100 ° C. or less at normal pressure 10 to 85% by weight. And a decomposing / removing agent for a resin coating film, comprising three components of 5 to 60% by weight of water. 2. A method of spraying or applying the resin coating composition-decomposing / removing agent according to claim 1 to a resin-coated part at a temperature of 50 to 100 ° C., or immersing a resin-coated product in said coating composition-removing remover. A method for decomposing and removing a resin coating film, comprising the steps of: