EP0161537A2 - End-capped fatty alcohol alcoxylates for industrial cleaning processes especially for bottle wasting and for the cleaning of metal - Google Patents

Abstract

The invention relates to the use of end-capped fatty alcohol alkoxylates as low-foam, foam-suppressing and biodegradable surfactants for industrial cleaning processes, in particular for bottle washing and metal cleaning.

Description

The invention relates to the use of end-capped fatty alcohol alkoxylates as low-foam, foam-suppressing and biodegradable surfactants for industrial cleaning processes, in particular for bottle washing and metal cleaning.

Highly alkaline cleaners are used to clean bottles in the beverage industry. The alkali dissolves, neutralizes or saponifies beverage residues and residues and converts the label glue into a highly foaming, water-soluble form. All of these processes run with high mechanics and thus favor the already high tendency to foam of starch and sugar breakdown products.

For this reason, these cleaning operations not only require surfactants that provide as little of their own foam as possible, they must also be stable under the highly alkaline conditions, i.e. they should not discolor and should not themselves provide foaming degradation products, as is known, for example, from nonionic surfactants of the prior art. Another important requirement for such surfactants is their foam-damping properties on the foam promoters resulting from the beverage residues and glue under cleaning conditions by means of alkali treatment. Another requirement is dispersing properties on the labels, for example, which are carried in by the laundry.

Another application involves industrial cleaning processes in the metal industry. Here, too, a very well-wetting alkaline aqueous solution is used at high pressure as a cleaning medium for removing drawing and rolling greases or organic corrosion inhibitors containing carboxyl groups. Here, the surfactants according to the invention should not only improve the wetting properties, but in particular for foam damping of e.g. Anionic surfactants of the alkylbenzenesulfonate type or other sulfonic acid groups and carboxyl group-containing surfactants contribute.

These desired properties are met, for example, by a class of nonionic surfactants commonly referred to as ethylene oxide-propylene oxide block polymers. They are described in U.S. Patent 2,674,619. Block polymers which have an amine compound as the starting molecule for the polymeric surfactant are particularly advantageous. These surfactants are also characterized by good low foaming and good dispersibility. Compared to standard surfactants, it is D / P High molecular weight compounds with a polyether structure, which are known to have particularly specific properties with regard to dispersion and foam damping. However, these nonionic surfactants, which are specially tailored to industrial cleaning processes, have the serious disadvantage that they are not sufficiently biodegradable according to the test methods required by the detergent law for surface-active compounds.

There are numerous patent applications dealing with the development of biodegradable low-foam surfactants.

For example, EP patent 34 275 also deals with low-foam, foam-suppressing surfactants for industrial cleaning processes. The disadvantage of this class of substances, which are ethoxylated and subsequently butoxylated aliphatic alcohols, is, however, that they tend to discolour under alkaline conditions and lose their foam-suppressing properties with prolonged use and start to foam themselves. Their foam-suppressing effect on alkylbenzenesulfonate is also only moderate.

European Patent No. 19173 describes low alkoxylated, also biodegradable, low-foaming surfactants. In comparison to the products according to the invention, however, these products very quickly lose their low-foaming, foam-suppressing properties if they are stored in the presence of alkali at higher temperatures or if they are tested for a long time.

From EP patent 36 550 it is known that the end groups of alkoxylated fatty alcohols with an alkyl radical of 8 to 20 carbon atoms and 4 to 30 alkylene oxide units can be closed by propylene. Low foam, alkali and, above all, acid stability are stated for these surfactants. However, as far as ethylene oxide / propylene oxide mixed adducts are concerned, the effect of these surfactants is not optimal in practice, especially since they are not sufficiently biodegradable. A disadvantage is the relatively complex and costly method of production, which prevents application in practice.

The person skilled in the art is aware that low foam, foam damping and alkali stability on the one hand and biodegradability, as required by the German Detergent Act and the associated regulation, on the other hand, are opposing requirements. How difficult it is, for example in the area of industrial metal cleaning and bottle washing, to come up with the surfactants that comply with the law the transition regulation for this surfactant class, which has now been extended for the second time, shows that it can also be technically accepted up to 1986.

It is therefore an object of the invention to provide a nonionic surfactant in technology which meets the desired requirements, in particular for technical cleaning processes.

in der R einen Alkylrest mit 8 bis 22 C-Atomen, X₁ und X₃ Ethylenoxideinheiten, wobei n und p für eine Zahl von 0 bis 10 stehen und die Summe von n + p wenigstens 2, bevorzugt wenigstens 5 und höchstens 9, ist, X₂ Propylenoxid- oder Butylenoxideinheiten, wobei m für eine Zahl von 1 bis 5, bevorzugt 2 bis 4 steht, und Z Methyl, Ethyl oder Allyl bedeuten, als schaumarme, schaumdämpfende und biologisch abbaubare Tenside in industriellen Reinigungsprozessen, insbesondere der Flaschenwäsche und Metallreinigung.The application relates to the use of nonionic surfactants of the formula I.

in which R is an alkyl radical with 8 to 22 carbon atoms, X ₁ and X ₃ ethylene oxide units, where n and p stand for a number from 0 to 10 and the sum of n + p is at least 2, preferably at least 5 and at most 9 , X ₂ propylene oxide or butylene oxide units, where m is a number from 1 to 5, preferably 2 to 4, and Z is methyl, ethyl or allyl, as low-foaming, foam-suppressing and biodegradable surfactants in industrial cleaning processes, in particular bottle washing and metal cleaning .

The special compounds of the formula I surprisingly achieve high foam attenuation, although it is known to the person skilled in the art that only low foam attenuation can be obtained by methyl end group closure. They have good low-foaming properties and, according to the regulations in the Federal Law Gazette dated 30.01.77, Part 1, pages 244ff, can be classified as perfectly biodegradable surfactants.

C-atoms, of which especially radicals on the basis of C ₁₃ / C ₁₅ Ox are particularly preferable for R are alkyl radicals having 10 to 18 _° alcohols and C _1O / ₁₄ C - ^Z ie leralkoholen ^g-, wherein p is 0, n is 5 to 9 and m are 2 to 4 and the end group of which has been closed by methyl and mixtures of these surfactants.

The starting materials for the preparation of the surfactants to be used according to the invention are, by definition, fatty alcohols or fatty alcohol mixtures with 8 to 22 carbon atoms. They can be branched and straight-chain, preferred are those which are as straight-chain as possible or only branched to a small extent. These are alcohols, such as octanol, nonanol, decanol, dodecanol, tetradecanol, hexadecanol, oxadecanol (stearyl alcohol) and mixtures thereof. Those which have been obtained by Ziegler or oxo synthesis are technically particularly preferred. These are mixtures that contain 9/11, 13/15 or 16/18 C atoms, prepared after oxosynthesis. The alcohol mixtures containing 8/10, 10/12, 12/16 and 16/20 carbon atoms obtained after the Ziegler synthesis are equally favorable. The C ₁₃ / C ₁₅ cut of the alcohol fraction obtained after the oxo synthesis is particularly advantageous.

The alcohol alkoxylates are prepared in a conventional manner and the alkoxylates obtained are then subsequently converted into the corresponding ether using an alkylating agent. The processes for the preparation of these surfactants are known from the literature and do not require a general description. The specific preparation of some selected compounds is dealt with in the examples.

The present examples illustrate the invention without, however, restricting it.

Manufacturing examples example 1

20.8 parts of C13 / C15 oxo alcohol and 0.1 part of potassium hydroxide are placed in an autoclave. At 110 to 120 ° C, 26.4 parts of ethylene oxide are continuously gasified. To complete the reaction, stirring is continued for 1 hour. 23.2 parts of propylene oxide are then added continuously at 130 to 140 ° C. and the mixture is left to react for 2 hours. This gives 70 parts of a fatty alcohol alkoxylate with an OH number of 85 to 88, which has a cloud point of 31 ° C in water according to DIN 53 917.

19 parts of the fatty alcohol alkoxylate obtained are mixed with the equimolecular amount of KOH at room temperature and converted into the alcoholate. The mixture is then etherified with 4.45 parts of dimethyl sulfate. the inorganic reaction products are separated from the end product by extraction with water. This process is repeated several times until an OH number of the end product ≤ 8 is reached. The rest of the water is removed by vacuum distillation, salt residues by filtration.

17 parts of an end-capped surfactant are obtained, the OH number of which is 7. Residual water according to Karl Fischer is around 0.3%. The cloud point 2% in 25% butylene diglycol is 68 to 69 ° C.

The following surfactants from Table 1 to be used according to the invention are prepared in an analogous manner; in accordance with the meaning of Z, reaction was carried out with dimethyl sulfate, diethyl sulfate, allyl chloride or benzyl chloride as the alkylating agent. The end group closures have a residual OH number of <15, preferably 8 8.

With the surfactants to be used according to the invention, the properties of low-foaming, low-foam and alkali stability with an optimum biodegradability of at least 80% are achieved in accordance with the above-mentioned legal regulation.

The surfactants to be used according to the invention are preferably used, for example, in industrial liquid and powder detergent formulations for bottle washing and metal cleaning, as is required in metalworking. The invention therefore also relates to cleaning formulations which, in addition to constituents which are conventional per se, contain the surfactants according to the invention.

The following frame formulation for a powdered detergent is used as an example of a formulation for bottle washing, the relatively good amounts of surfactant to be used according to the invention being sufficient because of the good wetting action:

As a general rule for a liquid cleaner, the following composition can be considered:

When used, this formulation is metered into a cleaning bath which contains 0.5 to 3% by weight of sodium hydroxide, advantageously in an amount of 0.3 to 1 kg / m ^3.

As a test for the alkali stability of the surfactants to be used according to the invention in the formulation given above and under cleaning conditions, 30 g of surfactant over 3 g of solid NaOH are stored at 50 ° C. for two weeks.

Under these stricter conditions, the surfactant solution must not discolor and the foam formation and in particular the foam damping properties should not be degraded as a result.

The test for foam formation is carried out according to the impact method DIN 53 902, sheet 1, but modified to the extent that a perforated disc with 22 openings with a stroke number of 20 and a stroke cylinder with a content of 1500 ml are used. The measure of the foam behavior is the foam height after 30 seconds.

V ₂ indicates the foam volume of the sample solution in ml in accordance with this DIN method. With V the foam volume in percent of the foam volume of the comparison solution.

For further characterization, the wetting capacity is tested according to DIN 53 001 in distilled water containing 2 g soda / 1 at 20 ° C. The network capacity allows a statement about the application properties in the above-mentioned applications. The wetting ability and the foam damping against foreign substances, but also the self-foaming ability often run against each other. Good foam dampers are usually poor wetting agents and good wetting agents often foam very strongly.

The foam-damping behavior is tested in accordance with the different application once in the dishwasher under protein load ("egg test"), and secondly the foam-suppressing effect on alkylbenzenesulfonate is examined in the dynamic foam apparatus.

• Durch magnetische Induktionsmessung wurde in einem Geschirrspülautomaten mit Hilfe eines Zählwerks die Zahl der Umdrehungen eines Spülarms bestimmt. Durch Schaumbildung, die besonders bei Anwesenheit von Proteinen (Eiweiß) auftritt, wird die Umdrehungszahl des Spülarms vermindert. Die Umdrehungszahl stellt somit wegen der verringerten Rückstoßkraft ein Maß für die Tauglichkeit von Tensiden in Reinigungsgeräten mit hoher Mechanik dar.

Egg test:

• The number of revolutions of a washing arm was determined by magnetic induction measurement in an automatic dishwasher using a counter. The number of revolutions of the washing arm is reduced by the formation of foam, which occurs particularly in the presence of proteins (protein). Due to the reduced recoil force, the number of revolutions represents a measure of the suitability of surfactants in cleaning devices with high mechanical properties.

The test time is 12 minutes, with the number of revolutions per minute being calculated from the total number of revolutions after certain times. The washing process is started at room temperature, after about 10 minutes the temperature of the rinsing water is 60 ° C.

Foam damping on alkylbenzenesulfonate in the dynamic foam apparatus is another laboratory method to determine the foam damping behavior to investigate anionic surfactants. The test apparatus is a continuously working circulation apparatus. The foam build-up is caused by the fact that a test beam flows continuously into the stock solution at a constant pressure in a calibrated tube with a diameter of 6 cm. This creates a product-specific foam height, which is measured in ml. If a foam booster, for example in the form of an alkylbenzenesulfonate, is added to this test solution, the foam-suppressing behavior of the foam-suppressing surfactants according to the invention can be investigated.

Table 2 shows the amount of foam for 6 ml, 12 ml and 18 ml of 2.5 l alkylbenzenesulfonate solution when using 0.3 g / 1 test surfactant, ie the smaller the amount of foam, the greater the damping potential of the Surfactants.

The results in Table 2 show that according to the DIN 53902 foam test, all of the products examined form practically no foam. The more practical egg test in a Miele dishwasher (type G 7735) shows a differentiation of the foam-suppressing properties to protein foam and values above 80 mean excellent foam damping.

The values for the wetting capacity of less than 265 for the majority of the surfactants examined show that products with high foam damping can also have excellent wetting effects.

The visual foam insulation values, measured in the dynamic foam apparatus, indicate a very high foam damping capacity of the investigated surfactants. These results are particularly important for practical use. Such favorable values have so far only been achieved with non-biodegradable surfactants.

Of particular note is the storage stability of the surfactants according to the invention according to the above. Alkaline stability test (30 g surfactant, 3 g solid NaOH, two weeks, 50 ° C). After two weeks of storage over solid sodium hydroxide, the values and surfactant properties shown in Table 2 are practically unchanged.

Claims (6)

1. Use of nonionic surfactants of the formula I

in which R is an alkyl radical with 8 to 22 carbon atoms, X ₁ and X ₃ ethylene oxide units, where n and p stand for a number from 0 to 10 and the sum of n + p is at least 2, X ₂ propylene oxide or butylene oxide units, where m is a number from 1 to 5, and Z is methyl, ethyl or allyl, as low-foaming, foam-suppressing and biodegradable surfactants in industrial cleaning processes. 2. Use of surfactants of the formula I according to claim 1, in which R is an alkyl radical having 10 to 18 carbon atoms, p 0, n 5 to 7 and m 2 to 4. 3. Use of surfactants of the formula I according to claim 1 or 2, in which R denotes the residue of a C ₁₃ / C ₁₅ oxo alcohol or C ₁₀ / C ₁₄ brick alcohol. 4. Use of surfactants of the formula I according to claims 1 to 3 in powdery cleaning formulations in an amount, based on the total weight, of 5 to 10% by weight or in liquid cleaning formulations in an amount of 10 to 30% by weight. 5. Powdery cleaning formulations containing surfactants of formula I according to claims 1 to 3 in an amount of 5 to 10 wt.% In addition to the usual ingredients. 6. Liquid cleaning formulations containing surfactants of the formula I according to Claims 1 to 3 in an amount of 10 to 30% by weight in addition to constituents which are customary per se.