DE3844183A1 - AQUEOUS CLEANER FOR METAL SURFACES - Google Patents

Description

The invention relates to an aqueous cleaner for Metal surfaces with a pH between 7 and 12.5 and a content of surfactant and usual builder substances and / or corrosion inhibitors and its use in Spraying process.

In the metalworking industry there are many Degreased metal surfaces in the production process and cleaned, e.g. B. after the cutting Processing before fine measurement or intermediate storage or before phosphating to remove Corrosion protection oils or lubricants. To this end it is common and advantageous to use aqueous solutions use because the also common cleaning with organic solvents, e.g. B. chlorinated hydrocarbons, because of the associated health and Groundwater hazard is problematic. Such aqueous Systems are e.g. B. the so-called neutral cleaners or but alkaline cleaners. The former are preferably in Syringes, the latter both in syringes and in diving used.

Have neutral cleaners in the usual Use concentration a pH between about 8 and 9.5. They contain surfactants, mostly non-ionic, as well as corrosion inhibitors, e.g. B. alkanolamine salts short-chain fatty acids with less than 10 carbon atoms. The Corrosion inhibitors serve to protect the treated Parts from corrosion during cleaning treatment, during Drying and subsequent storage (DE-C-26 14 234, EP-A-99 598).  

Alkaline cleaners with a pH value usually larger than 7 contain surfactants, especially anionic ones and / or non-ionic type, and so-called Builders, such as alkali carbonates, silicates, Phosphates, borates, gluconates or sodium or Potassium hydroxide.

The dirt adhering to the parts to be cleaned arrives when cleaning in the cleaner. Since this one Cost and environmental reasons usually take a long time is used, the detached accumulates in it Dirt, mostly oily contamination. With increasing The cleaners lose their dirt absorption Cleaning person. As a remedy, you can focus on Increase detergent chemicals, one measure, however, only limited promises success. As a rule, a Completed detergent flooded or completely or partially be rescheduled. Such measures don't just increase the chemical costs, but also burden the operational sewage system and the receiving water in considerable measure.

The object of the invention is to provide an aqueous cleaner for To provide metal surfaces that have the disadvantages of does not have known cleaner, in particular a significantly increased tolerance to oily Has impurities, and therefore significantly longer can be used.

The task is solved by the cleaner of the beginning mentioned type according to the invention in the manner is formulated that he is a polyglycol ether of the formula

C _n H _{2 n + 1} O (C₂H₄O) _x H

with n = 1 to 5 and x = 2 to 30.

According to a preferred embodiment of the invention cleaners containing methyl, Ethyl and / or isopropyl polyethylene glycol ether for Commitment.

In an advantageous development of the invention, the Polyglycol ether content in the cleaner 0.05 to 10 g / l. A concentration in the lower range is special with spray application, such in the higher range Diving is an advantage.

Like other cleaners, they also contain Invention expediently the usual framework substances. The surfactants are anionic or nonionic Kind preferred. As corrosion inhibitors, salts are one or more aliphatic carboxylic acids with 6 to 12 Carbon atoms with alkanolamine particularly suitable. It can however, other corrosion inhibitors can also be used.

The particular advantage of the cleaner according to the invention shows up when used in syringes. In contrast to the otherwise usual higher setting of the The addition of the polyglycol ether leads to surfactant concentration namely not for reinforced, undesirable foaming.

The invention is illustrated by the following examples closer and explained for example.

Quality steel sheets were used to carry out the experiment RSt 1405 with the dimensions 105 × 85 × 0.7 mm, through  

• - Steam degreasing with 1,1,1-trichloroethane
• - Wipe with a cotton rag
• - Steam degreasing with 1,1,1-trichloroethane
• - Pickling in 1.0% citric acid for 1 min Room temperature in diving
• - Rinse water for 1 min
• - Rinse in isopropanol for 0.5 min
• - Blow drying with compressed air
• - Oil with an anti-corrosion oil (Rustilo® 845 from Castrol)

had been prepared.

To determine the quality of the cleaner, the so-called minimum cleaning time (MRZ) with increasing Oil content determined. The minimum cleaning time is shortest cleaning time, which is required in order to subsequent rinsing full (greater than 95% of the Surface) to obtain wetted sheets.

Example 1

A cleaner, the

• - 3.6 g / l Na₂HPO₄ and
• - 0.4 g / l non-ionic surfactant (Antarox® BL 330 from GAF)

contained and was used in spraying at 55 ° C. To Simulation of the usually increasing in practice Contamination protection oil was in different amounts emulsified in the cleaner. The determined minimum cleaning times

Was the above cleaner 0.4 g / l Isopropyl triethylene glycol ether (i-C₃H₇-O- (CH₂-CH₂O) ₃-H) (GN 6129 the Zschimmer & Schwarz) were added, the following Get minimum cleaning times

Example 2

A cleaner, the

• - 3.6 g / l Na₂HPO₄ and
• - 0.4 g / l nonylphenol polyethylene glycol ether (Arkopal® N 100 from Hoechst AG)

contained and was used as in Example 1. The Minimum cleaning times were

The deletion foamed so much, however, that one Cleaner cannot be used in practice.

Example 3

A cleaner with a content of

• - 5 g / l Na₂HPO₄
• - 1 g / l Na₅P₃O₁₀
• - 0.4 g / l alkyl polyethylene glycol polypropylene glycol ether (Propetal® 99 from Zschimmer & Schwarz).

The minimum cleaning time for spray application and at 60 ° C amounted to

Was the above cleaner, whose surfactant content on 0.2 g / l had been reduced, 0.2 g / l one Methyl polyethylene glycol ether (CH₃-O- (CH₂-CH₂O) ₁₂-H) (GN 8384 from Zschimmer & Schwarz) admitted, the following resulted Minimum cleaning times

Example 4

A so-called neutral cleaner is used composition

• - 5 g / l diethanolamine
• - 0.8 g / l 2-ethylhexanoic acid
• - 0.8 g / l alkyl polyethylene glycol polypropylene glycol ether
  (Propetal® 99 from Zschimmer & Schwarz).

The minimum cleaning time required in spraying at 45 ° C was determined

Was the aforementioned neutral cleaner with 1 g / l Methyl polyethylene glycol ether (CH₃-O- (CH₂-CH₂O) ₁₂-H) added, resulted following minimum cleaning times

Example 5

A cleaner of the composition was used

• - 20 g / l Na₂SiO₃
• - 18 g / l Na₂CO₃
• - 10 g / l NaOH
• - 1.5 g / l dodecylbenzenesulfonate (Lutensit® ALBN from BASF).

The minimum cleaning times were in diving at 90 ° C determined and betrayed

After adding 2 g / l isopropyl ethylene glycol ether for the above-mentioned cleaner were the following Get minimum cleaning times

All examples with spray cleaning are common, that cleaner containing polyglycol ether itself at a spraying time that is significantly longer than the Minimum cleaning time was, no annoying foam formation showed.

Claims (5)

1. Aqueous cleaner for metal surfaces with a pH value in the range from 7 to 12.5 and a content of surfactant as well as usual builders and / or corrosion inhibitors, characterized in that it contains a polyglycol ether of the formula C _n H _{2 n +1} O ( C₂H₄O) _x Hmit n = 1 to 5 and x = 2 to 30 contains. 2. Cleaner according to claim 1, characterized in that he methyl, ethyl and / or Contains isopropyl polyethylene glycol ether. 3. Cleaner according to claim 1 or 2, characterized characterized in that it contains the polyglycol ether in a Contains amount from 0.05 to 10 g / l. 4. Cleaner according to one or more of claims 1 to 3, characterized in that it as Corrosion inhibitor is a salt of one or more aliphatic carboxylic acids with 6 to 12 carbon atoms Contains alkanolamine. 5. Use of the cleaner according to one or more of the Claims 1 to 4 in syringes.