DE2102842C3 - - Google Patents

Description

The usability of the variously lower chlorinated aliphatic hydrocarbons, in particular for liquid and / or vapor phase metal degreasing is known. In addition to their excellent These chlorinated solvents are therefore very suitable for technical cleaning effects Purposes as they are non-flammable and relatively cheap. Most used of these solvents carbon tetrachloride, trichlorethylene, perchlorethylene and methylchloroform (1,1,1-trichloroethane) are used. There is particular interest in methyl chloroform, its excellent dissolving power and low toxicity its high suitability for technical cleaning (degreasing) of metals condition.

, The advance of methyl chloroform in tech-. However, the niche area became more numerous because of its pronounced tendency to decompose in the presence Metals, especially aluminum, hindered. Although other chlorinated solvents, such as Percliloräthylen, compared to the by the most diverse Factors causing decomposition also need to be stabilized, this decomposition problem is at no compound nearly as severe as in the case of methyl chloroform. When you are unregulated If aluminum is exposed to methylchloroform, it will become unusable within a few minutes. .

While other chlorinated solvents use lower proportions of various compounds can be stabilized, experiments have confirmed that there are only a limited number of compounds there, soft compared to that made by metals

»5 caused decomposition of methylchloroform act as stabilizers, and that these compounds must be used in relatively large quantities. Because of the high requirements and the limited Choices were therefore made in the search for improved stabilizer systems, soft methyl chloroform and the metals treated with it, both in the liquid and in the vapor phase, in the presence of the most varied Protecting impurities from decomposition poses several problems. On the one hand

* 5 the stabilizers must be cheap because they are relatively high Quantities are required. On the other hand, the methyl chloroform can alternatively be used both as a liquid vapor phase degreasing can also be provided. As is common with liquid phase stabilization Problems other than vapor phase stabilization occur and are therefore of different kinds per se Stabilizers would be suitable, the components must be within a wide temperature range with one another be compatible.

Many known and commercially available stabilizer systems use nitroalkanes and epoxides used. However, such stabilizer systems can only be used to a limited extent for methyl chloroform. Even though Many of these systems are based on a nitroalkane-epoxy "base", resulting in the aforementioned combination as such, methyl chloroform does not always have a fully effective stabilization, and it depends depends on the choice of the other components of the respective system, whether such an effect is ultimately archivic will.

The object of the invention was to provide an improved, inexpensive multicomponent stabilizer system decomposition-stabilized on the basis of a nitroalkane-epoxy combination, in particular as a solution

to provide methyl chloroform suitable for liquid and vapor phase metal degreasing. This object is achieved by the invention.
The invention thus provides a 1,1,1-tri chloroethane containing a stabilizer system based on nitroalkanes having 1 to 3 carbon atoms (0.1 to 2 percent by weight of the stabilized 1,1,1-trichloroethane) and aliphatic Epoxides which have 3 to 8 carbon atoms and are optionally substituted (0.05 to 0.5 percent by weight of the stabilized 1,1,1-trichloroethane). which is characterized in that it is used as further stabilizer components A = propylene glycol monomethyl ether and / or trioxane and / or 1,3-dioxepane or di <

Combination of propylene glycol monomethyl ether and trioxane, with the stabilized 1,1,1-trichloro Ethane contains a total of 0.1 to 3 percent by weight of the additional substances specified.

According to a first preferred embodiment, the stabilized 1,1,1-trichloride also contains the stabilizer components H IVK-ihvlbupr.oi iind. Or tert-amyl alcohol in a mence of 0.1 to 1 percent by weight, based on the stabilized 1.1 , 1-TnchIorethane.

According to a second preferred embodiment, the stabilized 1,1,1-trichloroethane additionally contains nor the stabilizer components C = hexane, heptane, octane, hexene, trimethylpentene. Cyclopenta "' Cyclohexane, cyclohexene, cycloocrene or toluene in an amount of 0.1 to 2 percent by weight, based on the stabilized 1,1,1-Trichlorälhan.

According to a third preferred embodiment, the stabilized 1,1,1-trichloroethane also contains nor the stabilizer components D = N-methylmorpholine and / or diisopropylamine and / or pyrrolidine in an amount of 0.001 to 0.1 percent by weight, based on the stabilized 1 1 l-Trichloräihan.

The 1,1,1-trichloroethane preferably contains 1 to 10 percent by weight, in particular 4 to 6 percent by weight, of the entire stabilizer system.

;, 3-Dioxepane is a cyclic ether of the formula

CHo

H ₂ C '

H ₂ C

, CH,

CH,

The stabilized methyl chloroform according to the invention is particularly suitable for metal degreasing.

The effectiveness of the methyl chloroform is due to the presence of the aforementioned alcohols (B) considerably increased and when these alcohols are used, the addition of the hydrocarbons (C) can be increased even further. Even when component (D) is added, a for certain Degreasing methods optimally suitable Mcthylchloroform can be obtained. The inventive Stabilized methyl chloroform can be of the most varied by suitable choice of the stabilizer components Requirements in the field of metal degreasing are adapted and also for all others Used for purposes where a stabilized material is required.

In the case of the optionally substituted aliphatic C ₃ to C ₈ epoxides, it is important that the boiling point of the particular epoxide does not differ significantly from that of methyl chloroform. Specific examples of epoxides preferred according to the invention are propylene oxide, butene oxide, epichlorohydrin and methyl glycidyl ether.

The basic compounds designated as component (D) are soluble in methyl chloroform and generally have boiling points which essentially correspond to those of methyl chloroform. However, some of these basic compounds apparently form with the methyl chloroform and / or other components of the stabilizer system azeotropically boiling mixtures and thus change their actual measured boiling points.

Although it is difficult to identify the individual components of the stabilizer system used in accordance with the invention hestimmie functions are effective Propylene glycol monomethyl ether and / or trioxane and 1,3-dioxepane (A) is used as a reinforcing agent for the Niinialkan-Epcxirf-Basi.sko. ^ binuiion. While each of the three aforementioned additives (A) has about the same effectiveness, binary combinations such as trioxane, 1,3-dioxepane, have the best Fitness. This is particularly the case when the methyl chloroform stabilized according to the invention should contain a high level of stabilizer.

While methyl chloroform, which acts as a siahilizer system a Nirroa! kan epoxy combination and, in addition, propylene glycol monomethyl ether and or Containing trioxane and / or 1,3-dioxepane, which is effective for most purposes, is the one that can be incorporated Stabilizer content limited to a certain degree by the boiling point of component (A). However, it was found that the effectiveness of the stabilizer system, especially its resistance compared to aluminum when diluted at room temperature, through the further addition of methylbutynol and / or tert-amyl alcohol (B) is improved. This effect of the alcohol component is important because a merchantable product must be highly dilutable. without noticeably losing its effect. The aforementioned component (B) makes this requirement thus met without the problem which generally occurs when most alcohols are used for stabilization of methyl chloroform solutions occurs when they are used for vapor phase removal. The above problem is based in particular on the fact that different alcohols at room temperature carried out degreasing are effective, but at the reflux temperature often steel oiler Damage aluminum surfaces with which they are in contact. The inventively used Alcohols (B), on the other hand, are extremely effective.

The regulating effect of the aforementioned alcohols (B) in the case of a dilution is further intensified, and the distillation range of the stabilized solvent is further improved when an as Component (C) designated hydrocarbon such as heptane is added. If such relatively cheap Hydrocarbons can of course be used by reducing the proportion of the other cost savings can be achieved with expensive components.

If the corrosion of S'.ahl occurs in the presence of methyl chloroform in the vapor phase it may be expedient to add one of the basic compounds designated as component (D) to the methylchlorofoim to add. The stabilized methyl chloroform according to the invention can contain these basic compounds contain, regardless of whether an alcohol (B) and / or a hydrocarbon (C) is present or not.

The examples illustrate the invention.

The test methods that are used to determine the effectiveness of the various Stabilizer systems are used.

The "aluminum scratch test" consists in inserting an aluminum sheet metal strip into the test piece Immerse methyl chloroform solution and scrape the potted surface with a pencil with fine Scratching the tip so that a fresh surface is exposed to the solvent. This one exclusively

ijiiulii.iii-ve test is only a clearing procedure represent. Wl-ihi the stabilized Melhylehloroform this does not pass, it can of course also use the iiadi-

1 not described more stringent tests withstand. At the Aliiminium Kralztesl there is * Failure by 'bleeding', i.e. H. a constant discoloration of the solvent, on the pin displayed.

(line further and more thorough examination, which on stabilized methyl chloroform is used, the has already passed the aforementioned scratch test, mcIIi represents the "72-hour aluminum reflux". In this test, 100 ml of the solvent and 0.2 ml of water are poured into a condenser equipped flat-bottomed flask. Then will

2 aluminum ulcer strips inserted, one ilie-iT strips into the flask while the other is hung in the cooler, where the solvent vapor during the at milder. Reflux conditions Long-term test carried out with sheet metal strips. condenses on it and drips off from Ui / n. The aluminum reflux test also possesses; a predominantly qualitative nature, and poor results are easily recognized by the corrosion on the aluminum and the discoloration of the solvent. A Another purpose of the aluminum reflux test is! in determining the acidity of the staoilized Solvent by measuring the final pH. Unless otherwise noted, all systems / u start to have a pH of at least 7. After the previous 72 hours in the aluminum backfiow test the solvent is cooled and using a ratio of 1: 1 extracted with neutral reacting water. Subsequently the pH of the aqueous phase is determined. A low pH value naturally indicates a! the presence of acid dissolved by the decomposition of the solvent and thus to a Inadequate effectiveness of the stabilized system to prevent aluminum corrosion and solution

ίο middle! zcn> cizung hin.

The "Stahi Besländigkitstest" provides an analog test which is carried out in a manner very similar to the aforementioned aluminum reflux test will. In the Slahl resistance test, In place of the aluminum sheet metal tubes in the piston and radiator, steel tube strips are used, and one between Soxhlet-Ex'.rakiionsvo.richtuni arranged on the flask and the condenser. also contains one Steel block strips. The steel resistance test is generally quantitative, dr- the steel sheet strips weighed before and after. On the weight loss the re'ative effectiveness of the different systems determined.

² SB cis ρ ie I 1

Table I shows a comparison of the active wedge

various multi-component stabilizer systems or that of a simple nitroethane-epoxy system or propylene glycol mono diethyl ether alone to stabilize methyl chloroform.

table

Rehearse-
No. Stabilizer systemiii Shares
Weight
percent Total-
stabilizer-
mcnge
Weight
percent Aliiniiniuni-
scratch test *) 72-S
Pistons***) unden-alumin
Back nut test
Cooler**·) UiIl-
PH value ι ν ■
• 2 V Nitroethane /
Butene oxide
PGMÄ *)
Nitroethane
Butene oxide
PGMÄ 3.6
0.4
2.8
0.8
0.4
2.8
0.8
0.4
2.0
0.8
0.8
0.4
2.0
0.8
1.0
0.8
0.4
1.0
0.6
1.5 4.0
2.8
4.0
4.0
5.0
4.3 3
1
1
1
1
1 A.
A.
A.
A. C.
C.
A.
B. 6.0 4th Nitroethane
Butene oxide
PGMÄ 6.0
6.7 5
6th Trioxane
Nitroethane
Butene oxide
PGMÄ
Trioxane
Methylbutynol
Nitroethane
Butene oxide
PGMÄ .. 7.0 Trioxane
tcrt.-amyl alcohol ....

·) PGMA l'ropylene glycol monomethyl ether. **) 1 no change, 2 Locfcbildung, } γ- constant "bleeding". ·· *) Α no corrosion, B. easy .. ¹ corrosion, C. welding corrosion. ') V Comparison attempt.

• The values shown in Table 1 can be seen that the combination of nitroethane and Üutenoxid (Pobc 1) does not pass the aluminum scratch test and is therefore unsuitable as a stabilizer system for methyl chloroform. Also the propylene glycol monomethyl ether (Sample 2) fails with the aforementioned Tesi. There is therefore no reason to believe that a Combination of sample I and sample 2 is effective. However, as samples 3 and 4 show, at Use of a combination of nitroethane, butene oxide and propylene glycol monomethyl ether as well optionally obtained trioxane a stabilized methyl chloroform, which, as from the improved Result of the aluminum scratch test can be seen, completely suitable for cold degreasing processes. Samples 5 and 6 respectively show that the stabilized methyl chloroform of sample 4 was replaced by another Addition of methylbutynol or tert-amyl alcohol is so much improved that according to the 72-hour

Excellent aluminum reflux test under conditions simulating vapor phase degreasing Results are achieved.

B e i s ρ i el 2

Table II lists certain stabilizer systems which are outstandingly suitable according to the invention and which contain a basic component (D). It is the effectiveness of these systems to lower the Cor ^r osivität of methyl chloroform over steel shown. The results contained in Table II come from a comparative experiment in which one also contains only nitroethane and butene oxide

'5 methyl chloroform was investigated (results not shown) and show the reduction in weight loss of steel film strips which have been treated with stabilized methyl chloroform according to the invention.

Table II

Sample no.

Slabilisatorsystcm

/ Mile

Weight percent

Total amount of stabilizer

Weight percent

· / »Improvement

opposite to

Nitroethane /

Butene oxide)

Nitroethane
Butene oxide.
PGMÄ *) ..
Trioxane ...

Nitroethane

Butene oxide

PGMÄ

N-methylmorpholine

Nitroethane

Butene oxide

PGMÄ

Methylbutynol

N-methylmorpholine

·) Propylene glycol monomethyl ether.

·) Decrease in weight loss in the steel besides test.

0.8

0.4

1.0

1.0

0.8

0.4

2.0

0.025

0.8

0.4

2.0

1.0

0.025

3.2

3.2

4.2

none

20th

50

From the results shown in Table II it can be seen that propylene glycol monomethyl ether and Trioxane alone has no measurable effect on the stability of methyl chloroform in the presence of steel show that, however, by adding N-methylmorpholine an improvement is achieved which is considerably higher, albeit methylbutynol is present.

Furthermore, the stabilizer system of Sample No. 9 is compared with a stabilizer system from that of 0.8 percent by weight nitromethane and 3.425 percent by weight 1,4-dioxane according to the British patent 832 055 exists. It has been observed here that the amount of nitromethane corresponds to the amount of nitroethane is equivalent to. In addition, as much 1,4-dioxane has been added to the nitromethane as the rest Additions in sample no. 9 correspond to 1,1,1-trichloroethane stabilized with both stabilizer systems is subjected to the "steel resistance test". After 24 hours, the stabilizer system shows according to FIG Invention a 25% less corrosion than the system according to the British Palentschrift.

Example 3

A methyl chloroform solution which is stabilized with 0.4 percent by weight of butene oxide, 1.8 percent by weight of propylene glycol monomethyl ether, 1 percent by weight of tri oxane and 0.4 percent by weight of nitromethane shows excellent results in the aluminum scratch test. After the 72 hour aluminum reflux test , a final pH of 6.9 is achieved and the metal strip hung in the cooler shows only slight corrosion spots, while the solvent remains colorless and clear.

Example 4

A methyl chloroform solution, soft with 0.2 Ge v / weight percent epichlorohydrin, .0.2 weight percent methyl glycidyl ether, 1.8 weight percent propylene glycol monomethyl ether, 1 weight percent 1,3-Di oxepan, 0.8 weight percent nitroethane and 0.005 weight percent diisopropylamine stabilized is displayed outstanding as aluminum scratch test and the 72-hour AIuminium-Rückilußtest results

A final pI value of 7.9 is achieved, and the im Sheet metal strips suspended in a cooler manner remain undamaged, while the solvent remains colorless and clear.

Example 5

An IVicthylchloroform solution, which with 0.4 percent by weight Butene oxide, 1 percent by weight propylene glycol monomethyl ether, 0.5 percent by weight trioxane, 1.5 percent by weight tert-amyl alcohol, 0.8 percent by weight nitroethane, 1.5 percent by weight Hep-

10

tan and 0.02 percent by weight of N-methylmorpholine is stabilized, shows excellent results in the aluminum scratch test.

According to the 72 hour aluminum reflux test, has the metal strip hung in the cooler only shows slight corrosion stains. The pH value after the test is 7.6, while the solvent remains colorless and clear.

Additional methyl chloroform compositions and comparative compositions of the invention are shown in Table III .

table III 72-S
Pistons unden-alumin
Back nut test
cooler ium-
PH value Stabilizer system
(0.8 nitroethane and
0.4 _{% / 0} butylene oxide and
the others under 1 to 9
listed additives) Total-
stabilizer-
crowd
Weight
percent Aluminum-
Scratch test A. C. 6.0 l.PGMÄ 4.0 1 A. B. 5.5 2. trioxane 4.0 1 A.
A.
A.
A. C.
C.
C.
C. 4.0
5.4
4.4
6.0 3. 1,3-dioxepane 4.0
4.0
4.0
4.0 1
1
1
1 A.
C. C.
C. 4.2 4. PGMA + trioxane + 1,3-dioxepane ..
5. trioxane + 1,3-dioxepane 4.0
4.0 1
2 6. PGMA + trioxane 7 V ¹ .1,3-Dioxolane according to German open
1; reference 1 468 786 3 V ² . Diethylene glycol dimethyl ether according to
U.S. Patent 3,074,890
PGMÄ = propylene glycol monomethyl ether
A = no corrosion.
B = slight corrosion.
C = severe corrosion.
V = comparison test

Claims (5)

Patent claims: . I. 1,1,1-trichlorethylene, containing a stabilizer system based on nitroalkanes, which have 1 to 3 carbon atoms (0.1 to 2 percent by weight of the stabilized 1,1,1-Trichloriitha;, s and aliphatic epoxides which have 3 to 5 carbon atoms and are optionally substituted are (0.05 to 0.5 percent by weight of the stabilized 1,1,1-trichloroethane), thereby characterized in that it is used as additional stabilizer components A = propylene glycol monomethyl ether and / or trioxane and / or 1,3-Diox.epan or the Combination contains propylene glycol monomethyl ether and trioxane, the stabilized 1,1,1-trichloroethane a total of 0.1 to Contains 3 percent by weight of the specified additional substances. 2. 1,1,1-trichloroethane according to claim 1, characterized in that it also contains the stabilizer components B = methylbutynol and / or te <t.-Am> alcohol contains (0.1 to 2 percent by weight of the stabilized 1,1,1-trichloroethane). 3. 1,1,1-trichloroethane according to claim 1 and 2. characterized in that it is additionally the stabilizer components C = hexane, heptane, octane, hexene, trimethylpentene, Cyclopenta !!. Cyclohexane, cyclohexene, cyclooctene or toluene contains (0.1 up to 2 percent by weight of the stabilized 1,1,1-trichloroethane). 4. 1,1,1-trichloroethane according to claim 1 to 3, characterized in that it is additionally the stabilizer components D = N-methylmorpholine and / or diisopropylamine and / or contains pyrrolidine (0.001 to 0.1 percent by weight of the stabilized 1,1,1-trichloroethane). 5. 1,1,1-trichloroethane according to claim 1 to 4, characterized in that it is 1 to 10 percent by weight, preferably 4 to 6 percent by weight of the total stabilizer system.