NL9301339A - Peroxyacids or precursors thereof for use in the cleaning of textiles, and methods and devices for cleaning textiles using such peroxyacids or precursors. - Google Patents

Description

Title: Peroxyacids or precursors thereof for use in the cleaning of textiles, and methods and devices for cleaning textiles using such peroxyacids or precursors

The invention relates to cleaning textiles by means of wet washing processes.

The purpose of wet washing is to remove dirt and stains and to rid the laundry of micro-organisms and substances that give the laundry an unpleasant odor.

The types of dirt that occur in textiles can be divided into water-soluble dirt, water-insoluble dirt, and suspensible or emulsifiable dirt.

Water-soluble dirt includes, for example, sugars, acids, salts and urea; water insoluble dirt includes, for example, sand, clay, proteins, fats, oils, carbon black, dyes and micro-organisms.

Colloid soluble dirt includes; proteins, starch, foods, fats, oils and blood components.

In particular, the invention relates to wet washing processes which are carried out in a so-called washing tube. A washing tube is a (semi) continuous washing machine that comprises a number of chambers placed one behind the other. Different phases of the washing process are carried out in the different chambers. The phases (see Fig. 1) of such a wet washing process usually comprise a soaking phase (where the laundry is brought into contact with water and a detergent so that the dirt can swell), one or more soaking phases (washing at a temperature of about 85 ° C in the presence of detergent), a rinse phase (where detergent and loosened dirt are rinsed out), a bleaching phase (where bleach is added to oxidize and / or decolorize non-washable soiling) and a neutralization phase (where detergent and bleach residues are neutralized and rinsed out).

In general, the different phases in the washing process are spatially separated (chambers) in a wash tube (see Fig. 1). A conventional wash tube is shown in the figure.

Weeks take place in rooms 1 to 3. The soaking phase is carried out in chambers 4 to 8. In this phase it is possible to supply steam at various places to increase the soaking temperature.

During the sop phase, work is done partly in counter-current. The waste water is discharged into chamber 4.

After the soaking phase follows the rinsing phase, which is generally also carried out in counterflow.

After the rinsing phase, the bleaching phase follows, where hypochlorite solutions have generally been used so far, especially in processes for cleaning white goods and washing and chlorine-resistant fur goods.

The final stage is neutralization, where alkaline detergent residues and hypochlorite are usually neutralized using sodium hydrogen sulfite (bisulfite).

In an alternative process, peroxide is added in the second sop phase instead of hypochlorite (hydrogen peroxide process). In that case, there is no separate bleaching phase.

There are a number of drawbacks to the bleaching agents and / or disinfectants used hitherto, especially in combination with the usual neutralization by means of bisulfite.

First, cellulose fibers are poorly resistant to sodium hypochlorite and hydrogen peroxide, especially at high temperatures. As a result of this deterioration, the strength of the textile decreases. Protein fibers are also poorly resistant to hypochlorite. For example, polyamide is poorly resistant to perborate and hydrogen peroxide.

Therefore, in their application, these processes are actually limited to cotton and white goods.

Because certain types of dirt cannot be removed or can only be removed with a detergent, a bleaching process is often necessary. Dye stains and burnt-in protein stains can only be removed with a bleaching treatment or treatment with hot caustic soda.

Generally, a sodium hypochlorite solution is chosen at a PH of about 9.5 to 11 and at a temperature of 25 ° C. The effective chlorine concentration is about 0.25 g / l with a bleaching time of about 10 minutes. A higher temperature gives too much chemical wear.

The use of perborate and / or hydrogen peroxide requires a higher temperature (> 60 ° C) to achieve a slightly bleaching effect.

The environment for these bleaches must also be strongly basic. That is why they are usually added in a second sop phase.

The bleaching agents described above also have some disinfectant activity, although the disinfectant activity of peroxide is not great.

However, the prior art process liners cannot prevent the textile from being re-contaminated with micro-organisms in the final stages of washing, because the disinfectant must be completely neutralized. Especially in the case of hypochlorite, complete neutralization is necessary, because strong chemical wear occurs in the presence of residues of active hypochlorite in the laundry or in the water to be recycled in the process.

In industrial wet-wash treatment it is very important that water and energy are used efficiently to control costs and to reduce the amount of wastewater.

The water consumption of a washing tube is at least 13 liters (including steam) per kilogram of laundry.

Laundry wastewater includes detergents, soda, silicate, sodium sulfite and dirt. Limiting the amount of waste water is therefore also very important for laundries.

A good opportunity to save water and energy is to return (purified) process water to other parts of the process.

In the hypochlorite process (see Fig. 2) this can be done with water after the neutralization phase, which can be used again in the soaking phase; and with water after the soaking phase and / or rinsing phase, which can be used again in the soaking phase and / or the soaking phase. In the hydrogen peroxide process (see Fig. 3), water can be added again after the first soaking phase to the beginning of the first soaking phase. Without the present invention, this is the highest achievable reuse of process water.

In processes where hypochlorite or hydrogen peroxide is used, care must also be taken with the re-introduction of process water, because the water to be recycled in the soaking bath, for example, is warmer than usual in the soaking phase and in the presence of residues of hydrogen peroxide the fixation of protein stains occurs. while, in the case of hypochlorite, the increased temperature causes a strong bleaching effect and thus chemical damage to the textile.

The present invention provides a method and a device using a special peroxide compound in which microorganism recontamination does not occur in the final washing phases, allowing a high degree of reuse of the process water and yet provides sufficient bleaching action.

The present invention comprises a method for cleaning textiles by wet washing in at least five phases which can be subdivided into a soaking phase, at least one soaking phase, a rinsing phase, a bleaching phase and a neutralization phase, wherein in a second soaking phase or in the rinsing phase a peroxygen acid with at least 6 carbon atoms, or a compound which is converted in situ to such a peroxyacid is added.

A report by the Institute for Cleaning Techniques TNO briefly described a similar process in so-called open-end washing machines [M332 CO]. According to the report itself, the washing processes described therein did not meet the hygiene requirements that must be imposed on washing processes, certainly in the industrial wet laundry.

The addition of a much shorter peroxyacid in the last phase of the washing process is known per se. In German Offenlegungsschrift No. 3929335, peracetic acid in combination with acetic acid is added as a disinfectant. It is not used as a bleaching agent and cannot be used as a disinfectant that lasts longer, as it does not adhere well to the laundry. In addition, peracetic acid has many practical disadvantages. It is corrosive, corrosive and irritates skin, eyes and respiratory system. Actually, it can only be safely processed in fully automated dosing devices.

By choosing a peroxyacid with a somewhat longer carbon residue, or a compound that is converted therein during the washing process, better disinfection is achieved, because at least part of the peroxyacid can adhere to the fibers of the textile so that peroxyacid remains in the laundry after washing and thus the disinfecting effect of that peroxyacid also remains. Peroxyacids for use in the invention are compounds that have the formula R- (OO) -00H where R is a carbon chain or substituted carbon chain with at least 5 carbon atoms. Also compounds which satisfy the formula HOO (OO) - (CH2) n ~ (CO) OOH where n is greater than or equal to 4 can be used for the invention.

A number of peroxyacids to be used in the washing process are described, for example, in European patent application no. 0376360, but also other peroxyacids as described in European application no. 0458327, for example N-carbamoyl-1-aminoperoxy-undecanoic acid, can be used according to the invention. Preference is, however, given to diperoxydo-decanedioic acid (DPDDA).

In general, the peroxyacids mentioned above are readily biodegradable. Furthermore, methods are known for formulating said peroxyacids into completely safe products. Safe products can be in the form of granules or aqueous suspensions. Suspensions are preferred for use in wet washing processes. Although the amount required per kilogram of laundry and / or per liter of washing liquid of the peroxyacid is not directly critical and is mainly determined by the degree of contamination of the laundry, the amount of peroxyacid will usually be between 10 and 50 mmol per kilogram of dry laundry, which amounts to 2 to 10 mmol per liter of washing liquid.

Instead of the usual neutralization step with bisulfite, neutralization with an acid, preferably an organic acid and more particularly acetic or formic acid is used for the present invention.

By choosing this neutralization step, the disinfecting effect of the peroxyacid is further enhanced, while detergents and other detergent components are well neutralized.

The acid is preferably used in an amount such that a pH of 7.5 to 5 is achieved in the laundry, preferably between pH 7 and 6, which, for example, amounts to 1 gram per kilogram of dry laundry for formic acid.

Contrary to the washing processes according to the prior art, thermal disinfection is not necessary, because the disinfection of the peroxyacid in combination with its activation by the acid is sufficient. That is why it is possible to wash at a much lower temperature, which results in considerable energy savings and also gives fewer problems when the process water is returned during the soaking phase. Preferably, the washing process according to the invention is therefore carried out at a temperature between 25 and 75 ° C, in particular at a temperature between 45 and 65 ° C.

The methods of the invention can be carried out within wide limits of PH. In the neutralization phase, acid is used, which is why the PH is lower there, even if it is better to activate the peroxyacids.

An important advantage of the invention over the prior art processes is that much more of the process water can be reused in the washing process. The temperature of the water from the suds phase is lower and is therefore easier to return to the soaking phase where the temperature should not be too high due to the possible burn-in of stains. In the prior art processes, the temperature of the suds phase cannot drop because that high temperature is required for thermal disinfection. Figure 4 shows a washing process according to the invention where process water is returned to the washing process at various locations.

Optionally, the process water to be recycled before it is returned to the process can be subjected to a purification step. in this step the water is stripped as much as possible of any factors that disrupt the washing process, for example by means of a separation technique. By choosing the separation technique so that it can be used in the process, heat losses can be limited. Application of this method results in more efficient energy management, reduced water and detergent consumption and provides the possibility of a reduced degree of pollution of the waste water to be discharged.

Thanks to the lower washing temperature, which can be achieved thanks to the better chemical disinfection of the laundry by the peroxyacids according to the invention, it is now possible to reuse the water much more intensively.

The peroxyacids for use in the invention can be added in many ways in the washing process, for example in a solution with conventional solvents, as a granulate with the usual fillers, or as a suspension, or as a paste. They can also be added together with the detergent in the (or the first or second) suds phase.

The peroxyacids of the invention and the methods of the invention may be combined with any conventional further laundry treatments. They can be used in processes with the usual steps and with the usual means, in particular in the so-called industrial wet washing processes, such as those used in washing tubes, for example.

In industrial wet washing, a process is generally carried out using the following means.

Sea and / or deterrent agents

Soap is still regularly used in industrial wet washing, especially in combination with synthetic detergents. Soaps are generally sodium and / or potassium salts of fatty acids. The sodium salts generally provide hard soaps, while the potassium salts provide the soft soaps.

Anionic, nonionic or cationic detergents are used as synthetic detergents, which in structure often resemble soaps. Anionic detergents include: alkyl aryl sulfates, alkyl sulfonates, alkyl sulfates, sulfated alkyl ethylene oxide condensates, etc.

Nonionic detergents include: alkyl polyglycol ethers, amine oxides, polyalkyl saccharides, etc.

Cationic compounds are generally quaternary ammonium compounds of which two alkyl groups consist of 16 or more carbon atoms.

A commonly used detergent additive is, for example, sodium carboxymethyl cellulose. Trinitriloacetic acid is also often used. In addition, often optically white, alkali wax, soda, sodium metasilicate, sodium hydroxide, etc.

The above list is far from complete and therefore cannot be construed as limiting the present invention.

Description of the figures

Figure 1 gives an example of a five-stage washing process. 1 is the week phase; 2 is the soaking phase, 3 is the rinsing phase; 4 is the bleaching phase and 5 represents the neutralization phase.

Figure 2 is a washing tube suitable for carrying out the classic hypochlorite process in which the temperatures of the process water in the different phases are shown in degrees Celsius; the solid arrows represent the water flows, the broken arrows indicate the water to be returned and the numbers indicate the amount of water to be discharged.

Figure 3 shows a hydrogen peroxide process with bisul cycle neutralization, in which the temperatures of the process water in the different phases are shown in degrees Celsius; the uninterrupted arrows represent the water flows, the interrupted arrows indicate the water to be returned and the numbers at the arrows indicate the amount of water to be discharged in units of 1 / kg of laundry.

Figure 4 shows an embodiment of a washing tube and a washing process according to the invention in which the temperatures of the process water in the different phases are shown in degrees Celsius; the solid arrows represent the water flows, the broken arrows indicate the water to be returned and the numbers indicate the amount of water to be discharged.

The invention is further illustrated by the following examples.

Example 1.

1200 kg of laundry (per hour) is introduced into a wash tube according to the invention, together with standard patches of dirt (available from EMPA (Switzerland)). The soaking phase involves a 9 minute treatment with 220 ml of detergent at a temperature of 40 ° C on average and a PH of 10.5 on average.

The laundry is then subjected to a suds phase for 12 min. The suds phase comprises 330 ml of detergent and is carried out at an average of 66 ° C and a PH of an average of 10.

The laundry is then subjected to a second soaking phase, which does not include detergent, but does include DDPDA (32 g / kg of laundry). The laundry is then rinsed for 6 minutes and neutralized with 2.5 g / kg laundry acetic acid.

In the rinsing phase, 80% of the water is removed, purified and recycled in the soaking phase. In the neutralization phase, 10% of the water is removed and 90% is recycled in the second suds phase and in the soaking phase. Everything from the water released during neutralization and pressing of the laundry is returned to the soaking phase.

After neutralization, the test material is assessed for light emission. Hygiene is tested by taking bacteriological samples.

Example 2.

Example 2 describes a standard hypochlorite process for comparison.

1200 kg of laundry (per hour) is placed in a wash tube according to the invention, together with standard patches of dirt ((VEKOPROP = fat, carbohydrates, proteins and organic pigment), (KWIJOVE = quartz, iron oxide, fat), (SUNAK = blackcurrant juice ) (BLOOD = pig's blood)). The soaking phase involves a 9 min treatment with 60 ml of detergent at an average temperature of 39 ° C and an average PH of 10.6.

The laundry is then subjected to a suds phase for 12 minutes. The suds phase comprises 2.5 liters of detergent and is carried out at an average of 82 ° C and a PH of 11.5 on average.

The laundry is then subjected to a bleaching phase comprising hypochlorite (20 ml / kg of laundry). The laundry is then rinsed for 6 min and neutralized with 2.5 g / kg bisulfite laundry.

In the rinsing phase, 67% of the water supplied is removed, purified and recycled in the soaking and soaking phase. Everything from the water released during neutralization and pressing of the laundry is returned to the soaking phase.

After neutralization, the test material is assessed for light emission. Hygiene is tested by taking bacteriological samples.

Claims (29)

Method for cleaning textiles by wet washing in at least five phases which can be subdivided into a soaking phase, at least one soaking phase, a rinsing phase, a bleaching phase and a neutralization phase, in which a peroxyacid with at least 6 carbon atoms, or a compound which is converted in situ to such a peroxyacid is added. The method of claim 1, wherein the peroxyacid is diperoxydodecanedioic acid. The method according to claim 1 or 2, wherein the peroxyacid is present in an amount of 10-100 g / kg dry laundry. A method according to claim 1, 2 or 3, wherein an acid is added in the neutralization phase. The method of claim 4, wherein the acid is an organic acid. The method of claim 5, wherein the organic acid is acetic or formic acid. The method of claim 6, wherein the acetic or formic acid is present in an amount such that it results in a pH of 8 to 4 in the neutralization phase. A method according to any one of the preceding claims, wherein the washing liquid in the suds phase has a temperature between 25 and 75 ° C. The method according to claim 8, wherein the washing liquid in the suds phase has a temperature between 45 and 65 ° C. A method according to any one of the preceding claims, wherein the pH of the washing liquid in the suds phase is between 12 and 5. The method of claim 10 wherein the pH of the washing liquid in the suds phase is between 10 and 7. A method according to any one of the preceding claims, wherein the pH of the washing liquid in the neutralization phase is between 4 and 8. The method of claim 12 wherein the pH of the wash liquor in the neutralization phase is between 3 and 7. A method according to any one of the preceding claims, wherein the water from the bleaching phase is at least partially reused in the washing process. A method according to any one of the preceding claims, wherein the water from the soaking phase is at least partially reused in the washing process. A method according to any one of the preceding claims, wherein the water from the rinsing phase is at least partially reused in the washing process. The method of claim 14, 15 or 16, wherein the water to be reused is subjected to a purification step. A method according to claim 14, 15, 16 or 17, wherein the water is reused in the soaking phase. A method according to claim 14, 15, 16, 17 or 18, wherein the water is reused in the soaking phase. 20. Peroxyacid with at least 6 carbon atoms or a compound providing in situ a peroxyacid with at least 6 carbon atoms for use in a washing process for cleaning textiles by wet washing in at least five phases that can be divided into a soaking phase, at least a soaking phase, a rinsing phase, a bleaching phase and a neutralization phase. 21. Peroxyacid with at least 6 carbon atoms or a compound providing in situ a peroxyacid with at least 6 carbon atoms for use as a disinfectant in a washing process for cleaning textiles by wet washing in at least five phases which can be divided into a soaking phase , at least a soaking phase, a rinsing phase, a bleaching phase and a neutralization phase. 22. Peroxyacid with at least 6 carbon atoms or a compound providing in situ a peroxyacid with at least 6 carbon atoms for use as a bleaching agent in a washing process for cleaning textiles by wet washing in at least five phases which can be divided into a soaking phase , at least a soaking phase, a rinsing phase, a bleaching phase and a neutralization phase. 23. Peroxyacid with at least 6 carbon atoms or a compound providing in situ a peroxyacid with at least 6 carbon atoms for use as a disinfectant and bleaching agent in a washing process for cleaning textiles by wet washing in at least five phases that can be divided in a week phase, at least a soaking phase, a rinsing phase, a bleaching phase and a neutralization phase. An apparatus for performing a method according to any one of claims 1-19. Detergent for use in a wet-washing process, characterized in that it comprises, in addition to the usual components, a peroxyacid with at least 6 carbon atoms or a compound which provides in situ a peroxyacid with at least 6 carbon atoms. Granulate for use in a wet-washing process according to any one of claims 1-19, comprising a peroxyacid with at least 6 carbon atoms or a compound comprising in situ a peroxyacid with at least 6 carbon atoms and a conventional filler. A suspension for use in a wet-washing process according to any one of claims 1-19 comprising a peroxyacid with at least 6 carbon atoms or a compound comprising in situ a peroxyacid with at least 6 carbon atoms and a conventional filler. A solution for use in a wet-washing process according to any one of claims 1-19, comprising a peroxyacid with at least 6 carbon atoms or a compound comprising in situ a peroxyacid with at least 6 carbon atoms and a conventional solvent. A solution, granules, detergent or suspension according to claims 25-28 comprising diperoxydodecanedioic acid.