EP0990020A1

EP0990020A1 - Method for washing clothes, in particular working clothes

Info

Publication number: EP0990020A1
Application number: EP98937476A
Authority: EP
Inventors: Thomas Merz; Christine Schnepf; Khalil Shamayeli
Original assignee: Ecolab GmbH and Co OHG; Henkel Ecolab GmbH and Co KG
Current assignee: Ecolab GmbH and Co OHG
Priority date: 1997-06-20
Filing date: 1998-06-12
Publication date: 2000-04-05
Anticipated expiration: 2018-06-12
Also published as: WO1998059025A1; NO996307L; CA2295015A1; PL187141B1; ATE222284T1; DE59805198D1; BR9810220A; CA2295015C; DK0990020T3; US6398820B1; DE19726287A1; EP0990020B1; PL337508A1; NO996307D0

Abstract

The invention relates to a method for washing clothes, in particular working clothes. The clothes are washed in a washing machine of the type commonly used in industrial laundries, using a combination of products comprising at least two components: (A) a washing alkali component containing (A1) an anionic surfactant and a water-soluble silicate, and/or (A2) an alkali hydroxide and (A3) complex-forming agents; and (B) a surfactant component preferably containing a nonionic surfactant. After washing, the wastewater is treated in a membrane filtering system. Unlike known agents, the inventive product combination comprising components A and B does not negatively affect wastewater treatment in the membrane filtration system. In particular, it does not block the membranes.

Description

Process for washing laundry, in particular workwear

The present invention relates to a method for washing laundry, in particular workwear, in which the laundry is washed in a conventional washing machine for commercial laundries with a product combination of an alkali and a surfactant component and the wastewater is processed via a membrane filtration system and a product combination for use in commercial laundries containing an alkali and a surfactant component.

In commercial laundries, workwear and other textiles from the hotel and restaurant sector, hospitals, from the food industry, such as e.g. Slaughterhouses, butchers etc. as well as textiles and work clothing from the automotive sector. The soiling that occurs in workwear and in the commercial sector often leads to particularly high pollution of the wastewater. The aim is to treat the wastewater from commercial laundries before it is fed into the public sewage system by removing the pollutants.

To remove the pollutants and impurities, there is, for example, the option of passing the wastewater through membrane filtration systems after the washing process. The membrane filtration systems already known have proven to be very effective systems in the field of wastewater treatment. However, it has been found that the membranes clog very quickly when treating wastewater from commercial laundries. Studies have shown that the addition is due to the surfactants and polymers contained in the washing and cleaning agents. not for a complete cleaning, so that the original capacity of the membranes can no longer be reached and the membranes therefore only have a short service life.

From international patent application WO 92/05235, for example, a liquid, nonionic surfactant combination with improved low-temperature stability is known which a) 20 to 50% by weight of an alcohol ethoxylate, derived from primary, linear C ₂ -Ci5 alcohols with an average of 2 to 7 ethylene oxide groups (EO), b) 20 to 50 wt .-% of an alcohol alkoxylate, derived from primary Cι ₂ - Ci ₅ alcohols with an average of 3 to 7 ethylene oxide groups (EO) and 2 to 8 propylene oxide groups (PO), c) 5 to 50 wt .-% of an alcohol ethoxylate, derived from mixtures of primary linear and 2-position methyl-branched Cι ₂ -Ci ₅ alcohols (oxoalcohols) with an average of 2 to 8 ethylene oxide groups.

However, the problem of membrane blocking could not be completely solved.

The present invention had for its object to provide a method for washing laundry, in particular workwear, in a conventional washing machine for commercial laundries and subsequent treatment of the waste water via membranes, in which the laundry is washed with a product combination of surfactant and alkali components which has essentially the same cleaning effect as the agents known from the prior art, but does not impair the performance of the water treatment in the wastewater treatment by membrane filtration systems, in particular does not lead to blocking of the membranes and thus to a reduction in the flow rate. In addition, an increase in the flow rate in wastewater treatment compared to the flow of pure water was desired. The present invention relates to a method for washing laundry, in particular workwear, wherein the laundry in a conventional washing machine for commercial laundries with a product combination of at least two components

(A) containing a washing alkali component

(A1) anionic surfactant and water-soluble silicate and / or

(A2) alkali hydroxide and

(A3) complexing agents, and

(B) a surfactant component, preferably containing nonionic surfactant, is washed and the waste water is processed via a membrane filtration system.

Another object of the present invention is a product combination for use in commercial laundries from at least two components

(A) containing a washing alkali component

(A1) anionic surfactant and water-soluble silicate and / or

(A2) alkali hydroxide and

(A3) complexing agents, and

(B) a surfactant component, preferably containing nonionic surfactant.

Surprisingly, it was found that the use of the product combination according to the invention not only does not worsen the flow rate through the membranes in the wastewater treatment, but can even increase it in many cases, ie the product combination apparently has a cleaning effect on the membranes. This positive finding is also independent of the membrane material, so that work can be carried out with great advantage in particular on the common membranes based on polypropylene, ceramic and carbon.

The method according to the invention can be carried out in conventional washing machines for commercial laundries. No special measures are required for washing.

The washing alkali component (A) used according to the invention can be present both in solid and in liquid form. If component (A) is in solid form, it preferably contains anionic surfactant and water-soluble silicate (A1) and a complexing agent (A3). If the washing alkali component is added in liquid form, it preferably contains alkali metal hydroxide (A2), in particular as an aqueous solution, and a complexing agent (A3).

Any anionic surfactants customary in the field of washing and cleaning agents can be used as the anionic surfactant, such as, for. B. C ₈ -C- | ₈ alkyl sulfates, C ₈ -C ₈ alkyl ether sulfates, C ₈ -C ₈ alkanesulfonates, C ₈ -C ₁₈ α-olefin sulfonates, sulfonated C ₈ -C ₈ fatty acids, C ₈ -C ₈ alkylbenzenesulfonates , Sulfonic succinic acid mono- and -di-Cι- ₂ alkyl esters, C ₈ -C ₈ -alkyl polyglycol ether carboxylates, C ₈ -C ₈ -N-acyl taurides, C ₈ -C ₈ -N-sarcosinates, C ₈ -C ₁₈ alkyl isethionates and mixtures of the foregoing.

The anionic surfactants are preferably present in an amount of 1 to 10% by weight, particularly preferably in an amount of 2 to 6% by weight, based on the washing alkali component A.

All silicates used in the field of detergents and cleaning agents can be used as water-soluble silicates. Here, the silicates not only have the function of a washing alkali, ie to increase the pH, but also have builder properties. Coming as water-soluble silicates both crystalline and amorphous silicate into consideration. Particularly suitable are crystalline, layered sodium silicates of the general formula NaMSi _x 0 _{2x +} ι.yH ₂ 0, where M is sodium or hydrogen, x is a number from 1, 9 to 4 and y is a number from 0 to 20 and preferred values for x 2, 3 or 4. Such crystalline layered silicates are described, for example, in European patent application EP-A-0 164 514. Preferred crystalline layered silicates of the formula given are those in which M represents sodium and x assumes the values 2 or 3. In particular, both β- and δ-sodium disilicates Na ₂ Si ₂ 0 ₅ .yH ₂ 0 are preferred.

Amorphous sodium silicates with a modulus Na ₂ 0: Si0 ₂ of 1: 2 to 1: 3.3, preferably 1: 2 to 1: 2.8 and in particular 1: 2 to 1: 2.6 are also suitable. Amorphous sodium silicates which are delayed in dissolution and have secondary washing properties are particularly preferably used. The delay in dissolution compared to conventional amorphous sodium silicates can be caused in various ways, for example by surface treatment, compounding, compacting / compression or by overdrying. In the context of this invention, the term “amorphous” is also understood to mean “X-ray amorphous”. This means that the silicates in X-ray diffraction experiments do not provide sharp X-ray reflections, as are typical for crystalline substances, but at most one or more maxima of the scattered X-rays, which have a width of several degree units of the diffraction angle. However, it can very well lead to particularly good builder properties if the silicate particles deliver washed-out or even sharp diffraction maxima in electron diffraction experiments. This is to be interpreted as meaning that the products have microcrystalline areas of size 10 to a few hundred nm, values up to max. 50 nm and in particular up to max. 20 nm are preferred. Such so-called X-ray amorphous silicates, which also have a delay in dissolution compared to conventional water glasses, are described, for example, in German patent application DE-A-44 00 024. Particularly preferred are compacted / compacted amorphous silicates, compounded amorphous silicates and over-dried X-ray amorphous silicates.

The water-soluble silicates are preferably present in an amount of 10 to 60% by weight, in particular 20 to 50% by weight, based on component A.

Suitable alkali metal hydroxides are, in particular, KOH and NaOH, the latter being particularly preferred. The alkali metal hydroxides can be present in component A in an amount of 10 to 50% by weight, preferably 15 to 30% by weight, with the alkali metal hydroxide in the case of liquid preparations generally as an aqueous solution in a concentration of 10 to 50 wt .-% is present.

As a further component, component A contains one or more complexing agents. As complexing agents, customary complexing agents suitable for detergents and cleaning agents can be used, in particular salts of polyphosphonic acids, salts of organic polycarboxylic acids, such as citric acid, carboxyaspartic acid and nitrilotriacetic acid, and mixtures of the foregoing. The salts of polyphosphonic acids which are preferably the neutral reacting sodium salts of 1-hydroxyethane-1,1-diphosphonic acid, diethylenetriaminepenta-methylenephosphonic acid or ethylenediaminetetramethylenephosphonic acid. The complexing agent is preferably used in amounts of 0.1 to 4.0% by weight, in particular 0.3 to 2.0% by weight. Particularly suitable compounds have been N- (2-hydroxyethyl) -, NN-bis-methylenephosphonic acid (commercially available, for example, under the name Cublen® R 60 from Zschimmer & Schwarz) and the sodium salt of carboxyaspartic acid (commercially available, for example, under the description

Nervanaid® GBS 5 available from Rhône-Poulenc). Component A may also contain further water-soluble builders, for example phosphates, and soda as further ingredients.

The sodium salts of orthophosphates, pyrophosphates and in particular tripolyphosphates are particularly suitable as phosphates. Their content is generally not more than 60% by weight, preferably from 10 to 60% by weight, in particular from 15 to 40% by weight, in each case based on the washing alkali component A.

Another possible ingredient is soda, Na ₂ C0 ₃ , which helps to raise the pH of the wash liquor. Soda can be present in an amount of up to 50% by weight, preferably from 10 to 50% by weight, in particular from 15 to 30% by weight, based in each case on component A.

In addition to the ingredients mentioned, the washing alkali component (A) may contain known additives, such as co-builders, optical brighteners, colorants and fragrances, possibly small amounts of nonionic surfactants and small amounts of neutral salts such as sulfates and chlorides in the form of such washing alkali compositions their sodium or potassium salts, provided that these do not impair the positive properties of the process.

It was found in the context of the invention that cellulose derivatives, which are often used as graying inhibitors in detergents, often have a negative influence on the filterability of the waste water through membranes. Component A, like component B of the process according to the invention, is therefore preferably free of cellulose derivatives, such as, for example, carboxymethyl cellulose, hydroxyalkyl cellulose and alkyl cellulose.

The nonionic surfactants of the component B are preferably used in a preferred embodiment C _{_8-22} alcohol alkoxylates (B1) used. The C ₈ . ₂₂ -Alcohol alkoxylates are preferably derived from primary, saturated alcohols having 12 to 18 carbon atoms, in which the alcohol radical can be linear or methyl-branched in the 2-position or can contain linear and methyl-branched radicals in the mixture, as are usually present in oxo alcohol radicals.

The primary, saturated and linear alcohols used are preferably mixtures such as are present, for example, in alcohol mixtures of native origin, e.g. can be obtained by synthesis according to the Ziegler method or from native fatty acids by reduction.

The oxo alcohols are usually a mixture of linear and 2-methyl-branched alkanols, in which the proportion of the linear alcohols generally predominates. The alcohol residues have 12 to 15, preferably 13 to 14 carbon atoms. Technical mixtures can additionally contain parts with 11 to 15 carbon atoms.

The C ₈ . ₂₂ -Alcohol alkoxylates preferably have at least 5, particularly preferably at least 7, alkoxy groups. Component B1 contains ethylene oxide residues (EO) and / or popylene oxide residues (PO) as alkoxy groups. If component B1 contains only EO groups, the degree of ethoxylation is particularly preferably at least 7. If both EO groups and PO groups are present, the number of EO groups is preferably 4 to 8 and the number of PO groups is 2 to 8, in particular 3 to 4. The EO groups and PO groups can be randomly distributed, but preference is given to using compounds in which the alcohol radical is first completely ethoxylated and then propoxylated thereon, as is represented by the schematic formula R- (EO) _x - (PO) y is played. In this formula, R stands for the alcohol residue, x for the number of EO groups and y for the number of PO groups. In a further embodiment, a mixture (B2) of alcohol ethoxylates is used as the surfactant component

(a) 20 to 80 wt .-% alcohol alkoxylates, derived from primary, linear or methyl-branched in the 2-position C-ι ₂ -C ₂₂ alcohols with an average of 5 or more ethylene oxide groups (EO), and

(b) 80 to 20 wt .-% alcohol alkoxylates, derived from primary, linear or in the 2-position methyl branched C ₁₂ -C ₂₂ alcohols (oxo alcohols) with an average of 4 to 8 ethylene oxide groups and 3 to 8 propylene oxide groups (PO).

In a preferred embodiment, the surfactant component B preferably contains the fatty alcohol alkoxylate in an amount of 50 to 90% by weight, based on component B, and between 10 and 50% by weight of other conventional constituents which increase the washing performance and which Do not negatively affect wastewater treatment via membranes

As a further component, component B can preferably contain one or more C ₄ alkyl alcohols, which are preferably present in an amount of 2 to 10% by weight, based on component B. As C ₄ alkyl alcohols, methanol and ethanol are particularly preferred.

The washing performance in the process according to the invention can be increased further by adding one or more fatty alcohols as detergent boosters to the surfactant component B. Particularly suitable fatty alcohols are fatty alcohols with 8 to 18 carbon atoms or mixtures thereof, as can be obtained from naturally occurring fats and oils.

The fatty alcohols can be present in an amount of up to 20% by weight, preferably from 5 to 20% by weight, particularly preferably from 10 to 15% by weight, based in each case on the surfactant component B. The surfactant component B can be anhydrous or contain up to 20% by weight, preferably 5 to 15% by weight, of water. The water content only plays a subordinate role in terms of meterability and storage stability. However, since the non-ionic surfactants B1 are technical products that are obtained and offered in different quality and purity, it can happen that the concentrates become cloudy when certain technical product batches are used or that gel-like precipitates form. This clouding and precipitation are reliably avoided by adding water. Additions of 5 to 10% by weight are generally sufficient for this.

The agents can contain further additives, provided that it is ensured that they are soluble and do not change the advantageous properties of the concentrates. These include in particular dyes and fragrances with which the intrinsic color or odor of the mixtures is covered. Although other solvents can in principle be added, they are generally not required.

The surfactant component B usually behaves like a Newtonian liquid, ie its viscosity is independent of the shear forces. Such agents are therefore easy to convey and dose, their viscosity changing comparatively little depending on the temperature. They are stable in storage even after several months of storage in a climatic cabinet at repeatedly changing temperatures between minus 10 ° C and plus 40 ° C, ie they do not tend to separate. The concentrates have a liquid consistency of at least 0 ° C. They can be in liquid or solid form between minus 10 ° C and 0 ° C. The concentrates in solid form at these temperatures also give clear and homogeneous liquids when thawed. These properties make them particularly suitable for fully automatic dosing in commercial laundries. Other suitable product additives can be optical brighteners, enzymes, bleaching agents from the per-compound class, which are usually used together with activators, active chlorine compounds and colorants and fragrances.

The method according to the invention is particularly suitable for washing heavily soiled work clothing and is distinguished by a high washing power compared to soils containing mineral oil.

In a preferred embodiment, at least one quaternary ammonium compound is added to the laundry in the last rinsing bath. Any ammonium compounds which do not block the membrane during wastewater treatment are suitable as quaternary ammonium compounds, and dideyldimethylammonium chloride has proven to be particularly suitable. The quaternary ammonium compound is preferably added to the last rinsing bath in an amount of up to 10 g / l, particularly preferably from 0.05 to 2 g / l, in particular from 0.1 to 1 g / l of rinsing water.

The wastewater obtained from carrying out the washing process, including any rinsing steps that may be carried out, is treated according to the invention by passing it through a membrane filtration system. In a preferred embodiment, the waste water is passed through a plurality of membranes arranged one behind the other. It is also possible to pass the wastewater and the pre-treated wastewater through a membrane several times. The number of membranes arranged one behind the other is usually determined as a function of the amount of water to be processed per unit of time and depends on the size of the membrane.

The waste water can be passed through the membranes or circulated through the membranes until the water is of sufficient purity. To the cost of the overall washing process, especially the To reduce the water requirement, the water purified in this way via the membranes can be used for the prewash and, depending on the quality of the membrane, also for the clear wash and / or for the first or second rinsing bath.

The residue obtained from membrane filtration can be disposed of in a manner known per se.

Examples

Example 1

A wash liquor containing 0.33 g / l of a washing alkali component A and 0.16 g / l of a surfactant component B was used to wash workwear. These products had the following composition (in% by weight): A: sodium triphosphate 20.0

Sodium alkyl benzene sulfonate 2.5

Sodium silicate (Si0 ₂ : Na ₂ 0 = 1: 1): 47.0

Acrylic acid-maleic acid copolymer as Na salt: 2.0

Na-hydroxyethane diphosphonate: 0.4

Sodium carbonate 25.0

C _12/14 fatty alcohol + 5 EO + 4 PO: 1, 5

Rest of water, perfume, optical brightener

B: C _12/14 fatty alcohol + 5 EO + 4 PO 75.0

Isotridecanol + 5 EO 21, 0

Rest of perfume and water

The wastewater obtained after the washing process was adjusted to a pH of 8 and filtered at a temperature of approximately 45 ° C. through a polypropylene membrane from Microdyn (pore diameter 0.2 μm). The inlet pressure was 0.8 bar and the outlet pressure was 0.4 bar.

The flow rate of pure water at 20 ° C. before the solution was passed through (t = o) and after the end of the test (t = oo) was determined as a comparison value. Example 2 (comparison)

An aqueous solution containing 0.05% by weight of a conventional laundry detergent of the following composition was tested as in Example 1. Comparative product:

88% by weight mixture of sodium citrate and sodium gluconate 11% by weight mixture of carboxymethyl cellulose and methyl cellulose 1% by weight nonionic surfactant

The results are shown in the table below:

It is clear from the experiments that the performance of the membrane in Example 1 (according to the invention) was hardly changed compared to its performance using pure water. On the other hand, in example 2 (comparison) the was hardly changed. On the other hand, the performance of the membrane decreased continuously in Example 2 (comparison) and could not be regenerated even by rinsing with water.

Claims

claims

1. A method for washing laundry, in particular workwear, wherein the laundry in a conventional washing machine for commercial laundries with a product combination of at least two components

(A) containing a washing alkali component

(A1) anionic surfactant and water-soluble silicate, and / or

(A2) alkali hydroxide and

(A3) complexing agents, and

(B) a surfactant component, preferably containing nonionic surfactant, is washed and the waste water is processed in a membrane filtration system.

2. The method according to claim 1, characterized in that as the anionic surfactant C ₈ -C ₈ alkyl sulfates, C ₈ -C ₈ alkyl ether sulfates, C ₈ -C ₈ alkane sulfonates, C ₈ -C ₈ -α-olefin sulfonates, sulfonated C ₈ -C ₈ fatty acids, C ₈ -C ₈ alkylbenzenesulfonates, sulfonic succinic acid mono- and di-C 1 -C ₂ alkyl esters, C ₈ -C ₈ alkyl polyglycol ether carboxylates, C ₈ -C _{8 8} -N-acyl taurides, C ₈ -C ₁₈ -N-sarcosinates, C ₈ -C ₁₈ alkyl isethionates and mixtures of the above are included.

3. The method according to claim 1 or 2, characterized in that the water-soluble silicate is selected from the group consisting of crystalline, layered sodium silicates of the general formula NaMSi _x 0 _{2x +} ι.yH ₂ 0, where M is sodium or hydrogen, x is a number from 1, 9 to 4 and y is a number from 0 to 20 and are preferred values for x 2, 3 or 4, and amorphous sodium silicates with one module Na ₂ 0: Si0 ₂ from 1: 2 to 1: 3.3, preferably 1: 2 to 1: 2.8 and in particular from 1: 2 to 1: 2.6 and any mixtures of the above.

4. The method according to any one of claims 1 to 3, characterized in that the complexing agent is selected from polyphosphonic acids, in particular 1-hydroxy-ethane-1, 1-diphosphonic acid, diethylenetriamine pentamethylene phosphonic acid, ethylene diamine tetramethylene phosphonic acid, N- (2- Hydroxyethyl) -, NN-bis-methylenephosphonic acid and its salts, and carboxyaspartic acid and its salts.

5. The method according to any one of claims 1 to 4, characterized in that the nonionic surfactant is selected from the group consisting of C ₈ . ₂₂ -Fettalkoholalkoxylaten with at least 5 alkoxy groups, in particular C ₈ -ι -Fettalkoholalkoxylat ₈ with at least 5 alkoxy groups, C ₈ -ι ₈ fatty alcohol ethoxylate containing at least 7 ethoxy groups, C ₈ ₈ -ι - fatty alcohol ethoxylate / propoxylate containing at least 4 ethoxy and at least 2 Propoxy groups in the molecule and any mixtures of the above.

6. The method according to any one of claims 1 to 5, characterized in that a mixture containing as nonionic surfactant

(a) 20 to 80 wt .-% alcohol alkoxylates, derived from primary, linear or methyl-branched in the 2-position C ₂ -C ₂ alcohols with an average of 5 or more ethylene oxide groups (EO), and

(b) 80 to 20 wt .-% alcohol alkoxylates, derived from primary, linear or in the 2-position methyl branched C ₂ -C ₂₂ alcohols (oxo alcohols) with an average of 4 to 8 ethylene oxide groups and 3 to 8 propylene oxide groups (PO), is used .

7. The method according to any one of claims 1 to 6, characterized in that component B contains 2 to 10 wt .-%, based on component B, of one or more Cι- alkyl alcohols, especially methanol and / or ethanol.

8. The method according to any one of claims 1 to 6, characterized in that component B 5 to 20 wt .-% C ₈ . ₂₂ fatty alcohol, based on component B, contains.

9. The method according to any one of claims 1 to 8, characterized in that components A and B are free of cellulose derivatives.

10. The method according to any one of claims 1 to 9, characterized in that the laundry is rinsed after washing, a quaternary ammonium compound, in particular didecyldimethylammonium chloride, being added to the last rinsing bath.

11. Product combination for use in commercial laundries consisting of at least two components

(A) containing a washing alkali component

(A1) anionic surfactant and water-soluble silicate, and / or

(A2) alkali hydroxide and

(A3) complexing agents, and

(B) a surfactant component, preferably containing nonionic surfactant.