FI84628B - METHYLENKLORIDBASERAD KOMPOSITION OCH FOERFARANDE FOER AVFETTNING AV METALLER SOM BASERAR SIG PAO ANVAENDNINGEN AV KOMPOSITIONEN. - Google Patents

Description

1 84628

The present invention relates to a methylene chloride-based mixture which can be used for degreasing metals and which contains stabilizers. The invention further relates to a method for removing grease from metals based on the use of such a mixture.

Chlorinated hydrocarbons, due to their solubility, non-flammability, and relatively low boiling point, are most commonly used to degrease metals, textiles, ceramics, and glass.

Methylene chloride is particularly stable in oxidation, hydrolysis and pyrolysis. It is not involved in any photochemical reaction. Its low boiling point allows it to be used at low temperatures. All these properties thus make it an excellent solvent for metal degreasing.

However, in this operation, it may react with aromatic compounds added during the processing of light metals.

According to one reaction mechanism (of the Friedel-Crafts type), hydrochloric acid and heavier compounds are formed which contaminate methylene chloride. Thus, there is a risk of explosion due to decomposition (formation of acid chloride, phosgene and hydrogen chloride gas).

To overcome these disadvantages, small amounts of organic substances must be added to the methylene chloride to prevent this reaction by stabilizing the methylene chloride.

Stabilized methylene chloride compounds have been proposed in the past. U.S. Patent 3,887,628 discloses methylene chloride, 2,84628 containing 0.05-2% butylene oxide and propylene oxide. U.S. Patent 3,923,912 describes methylene chloride containing 0.05-2% acetone or methyl ethyl ketone and optionally propylene oxide. U.S. Patent 4,108,910 describes methylene chloride containing an epoxide and an aliphatic monoether. EP 11,658 describes methylene chloride stabilized with ethyl or methyl formate.

It is therefore an object of the invention to provide a mixture which can be used for degreasing metals and which is stable in the presence of light metals such as aluminum or its alloys.

The mixture according to the invention thus contains methylene chloride and, in addition, as stabilizers a) propylene oxide or butylene oxide, b) acetone and c) tetrahydrofuran, each of components a, b and c comprising 0.05-5% by weight of the total weight of the mixture.

The total amount of propylene oxide or butylene oxide used can thus be 0.05 to 5% by weight of the total weight of the mixture, and preferably 0.2 to 2%. Preferably propylene oxide is used.

The total amount of acetone may be 0.05-5% by weight of the total weight of the mixture, and preferably 0.2-2%.

The total amount of tetrahydrofuran may be 0.05 to 5% by weight of the total amount of the mixture, and is preferably 0.2 to 2%.

The mixture according to the invention is prepared simply by mixing the ingredients with methylene chloride. This stirring can be performed at room temperature and more specifically at 5-30 ° C.

The present invention also relates to a process for degreasing 3,84628 metals with a mixture according to the invention, which process comprises contacting the metals with a mixture of 0.2-2% by weight of each of the above components a, b and c.

Degreasing can be performed in the vapor phase or in the liquid phase, depending on conventional procedures.

Example

A mixture of the formula (% by weight) is prepared: - methylene chloride 98 - propylene oxide 0.5 - acetone 1 - tetrahydrofuran 0.5.

This mixture passes the BAM test (Bundesanstalt för Material-prilfung, Federal Republic of Germany).

It will be recalled that the 4 steps of the BAM experiment are: 1) To 100 ml of the mixture are added 100 ml of toluene, 0.7 g of AlCl 3 and 18 g of aluminum strips. The mixture is kept under reflux for 18 hours in a mother liquor at 58 ° C, 2) 1 g of zinc stearate is added to the mixture 1) and then refluxed for 18 hours, 3) 10 ml of oleic acid is added to the mixture 1) and then refluxed for 18 hours, 4 ) extract 300 g of the mixture into three 100 ml fractions and then perform test 1) on all 3 fractions.

BAM can accept the mixture if no reaction occurs during these experiments.

Claims (4)

4,84628 1. A methylene chloride-based composition having the ability to stabilize a metal or a certain stabilizing agent, comprising the steps of: och c utgör 0,05-5 vikt-% av kompositionens totalvikt. A methylene chloride-based mixture which can be used for degreasing metals and which contains stabilizers, characterized in that it contains as stabilizers a) propylene oxide or butylene oxide, b) acetone and c) tetrahydrofuran each of components a, b and c in an amount of 0.05-5 -% of the total weight of the mixture. 2. A composition according to claim 1, the composition of which comprises components a, b and c of the nervous system in which 0.2-2% of the total composition is present. 5,84628 Mixture according to Claim 1, characterized in that the amount of each component a, b and c is 0.2 to 2% of the total weight of the mixture. 3. A composition according to claims 1 or 2, comprising a stabilizer comprising propylene oxide, acetone and tetrahydrofuran. Mixture according to Claim 1 or 2, characterized in that it contains propylene oxide, acetone and tetrahydrofuran as stabilizers. A method for removing grease from metals, characterized in that the metals are contacted with a mixture according to claim 2 or 3. 4. For the manufacture of metallic materials, the provisions relating to metallic provisions are in contact with the composition of claim 2 or 3.