EP0208989B1 - Process for cleaning furs and leather - Google Patents

Abstract

Process for cleaning furs and leathers by treating these materials with pieces of open-celled polyurethane foam having a density of from 60 to 120 kg/m<3> which have been treated with halocarbons. A polyurethane foam suitable for this purpose is obtained by reacting mixtures of polyalkylene glycols having an equivalent weight of from 200 to 2000 and polyhydroxy compounds having an equivalent weight of from 30 to 100 with isocyanato-containing precursors of polyisocyanates and polyalkylene glycols having an equivalent weight of from 50 to 500, preferably 300. Polyurethane foams of this kind are very retentive of the solvent, which is released only gradually. This ensures very gentle cleaning.

Description

Many items of clothing made of real fur cannot be cleaned in organic solvents because of excessive degreasing without risk of damage. For this reason, most fur clothing is treated according to the so-called cleaning process. According to this method, the worn and soiled furs are moved together with solvent-soaked hardwood shavings in a rotating refining drum. By touching the fur hair with the shavings, the dirt is removed from it, whereby the mechanical abrasion supports the dirt removal. After the purification of about 20 minutes, the fur clothing is reloaded into a shaking barrel and freed of the adhering wood chips. The shaking time is 20-30 minutes depending on the hair length. However, part of this detergent remains in bags and food after shaking and must be removed by hand. With short-haired fur, e.g. Persians, there is also the danger that these fur skins will be degreased too much due to excessive solvent absorption and will be damaged as a result of the weight gain during their movement in the rotating drum. Another disadvantage is that the dirty hardwood chips can no longer be used, so they have to be discarded after a single treatment. Since this material still contains solvents, disposal is a real problem. Soiled linings must be sprayed with water or an aqueous surfactant solution before this procedure. In the event of heavy soiling, the lining must be separated from the item of clothing and cleaned separately in a cleaning machine with solvent. The cleaning process described is therefore time-consuming and associated with a lot of manual work and disposal problems.

The object of the invention is to develop a method in which the fur clothing is just as gentle, or still treated more gently compared to the known refining processes, but cleaned faster and more effectively.

In the specialist book "Leather, furs, synthetic leather and their cleaning" by R. Mari and E. Bockelmann 1973, pages 29 and 30, a refining process developed by Kreussler for suede with low soiling is described. Then you clean the leather clothing with polyurethane sponges (size 10 x 10 cm), which fill about a quarter of the drum volume and are soaked with perchlorethylene (tetrachlorethylene) and with licker oil. Information about the properties of these sponges, e.g. However, there is a lack of solvent absorption, solvent retention depending on time, as well as abrasion resistance and compression hardness.

The invention relates to a process for cleaning furs and leather by treating these materials with molded parts made of open-cell polyurethane foam with a density of 60 to 120 kg / m³, these molded parts being impregnated with halogenated hydrocarbons.

The open-cell polyurethane foam is obtained by reacting mixtures of polyalkylene glycols with an equivalent weight of 200 to 2000 and polyhydroxyl compounds with an equivalent weight of 30 to 100 with isocyanate group-containing pre-adducts of polyisocyanates and polyalkylene glycols with an equivalent weight of 50 to 500, preferably 300.

The polyalkylene glycols used according to the invention are prepared in a conventional manner by adding alkylene oxides to compounds with at least two active hydrogens. Examples include ethylene glycol, 1,2-propanediol, 1,6-hexanediol, glycerin, trimethylolpropane, pentaerythritol or sorbitol. Suitable alkylene oxides are ethylene oxide, propylene oxide or butylene oxide or their Ge mix. In the case of mixtures of alkylene oxides, the polyalkylene glycols can be present as block polymers or the alkylene oxides are added up in a statistical distribution. The molecular weight of the polyalkylene glycols can vary within wide limits, it is adjusted so that the above-mentioned equivalent weight of 200 to 2000 is maintained. Polyalkylene glycols with an equivalent weight of 300 to 1000 with more than 50 mol% of primary hydroxyl groups are preferred. The polyalkylene glycols are used together with those polyhydroxyl compounds which have an equivalent weight of 30 to 100. Typical examples are ethylene glycol, diethylene glycol, 1,4-butylene glycol, glycerin and trimethylolpropam.

The isocyanate component used according to the invention is a diisocyanate which is modified with a polyethylene glycol. The polyethylene glycol has an equivalent weight of 50 to 500, preferably 300. Examples of suitable isocyanates are tolylene diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, polyphenylpolymethylene polyisocyanate and mixtures thereof. The preferred isocyanate is tolylene diisocyanate, which can exist in its isomeric 2,4-form or 2,6-form or as a mixture of the two isomeric forms. A suitable mixture of isomers contains approximately 80% 2,4-isomer and 20% 2,6-isomer, although other ratios can also be used successfully. The amount of isocyanate added should be adjusted to the remaining components present in the reaction mixture so that the isocyanate index, ie the ratio between isocyanate groups and hydroxyl groups, present in the mixture is approximately 0.85 to 1.25, preferably 1.00 to 1.10. Other starting materials used in the invention, such as foaming agents and catalysts, are the same as conventional flexible urethane foams. If necessary, a foam stabilizer, a refractory additive, etc. can also be added. Examples of foaming agents are Water and fluorinated hydrocarbons such as trichlorofluoromethane and dichlorodifluoromethane. Examples of the catalyst are amino compounds such as trimethylamine, dimethylbenzylamine, N-ethylmorpholine, triethylenediamine (and its formic acid salt), dimethylpiperazine, 1,2-dimethylimidazole, dimethylaminoethanol, diethanolamine, triethanolamine, diethylaminoethanol, 1,8-diazabicyclo (5 0) - undecen-7 (and its phenol salt) and tin compounds such as dibutyltin dilaurate and tin octoate. Examples of the foam stabilizers are silicones and other surface-active agents.

To produce the polyurethane foams from the above-mentioned starting materials, no special technique is required which differs from the known production of customary flexible urethane foams. The cell formation and correspondingly the density of the polyurethane foam are regulated by adjusting the amount of water and other blowing agents such as trichlorofluoromethane or methylene chloride added in the usual way. The starting materials according to the invention are therefore mixed together in the correct order, in the appropriate amounts at room temperature or elevated temperature and the mixture obtained is foamed.

The polyurethane foams suitable in the context of the present invention should have a density of 60 to 120 kg / m 3. Higher densities are also possible but uneconomical to manufacture. The polyurethane foam is cut into shaped pieces of a suitable size. The shaped pieces are preferably spherical or cube-shaped and have a volume of 15 to 1000, in particular 100 to 200 ml. These shaped pieces or sponges are then impregnated with a sufficiently large drum content with a fluorine or chlorinated hydrocarbon, for example with trichlorofluoromethane, in a conventional cleaning machine. 1,1,2-trichloro-1,2,2-trifluoroethane, tetrachlorethylene or dichloromethane. The amount of these solvents based on the Polyurethane sponges, is about 100 to 300%. Then the material to be cleaned is added to the impregnated sponges and this material is rotated together with the sponges in the cleaning machine for a sufficiently long time. The fill factor (kg goods: drum volume) depends on the type of material to be cleaned. For short-haired and semi-smoked furs (e.g. mink, raccoon) as well as for furs with velvet side or nappalan dressing, this fill factor is 1:20 to 1:30, for full-smoke and long-haired furs (e.g. Mongolin lambs, Canadian red foxes, noble foxes) 1: 50 to 1:80.

To increase the cleaning effect, tough, hard sponges can be added to the product, and to improve product failure, auxiliary agents such as cleaning enhancers, softening agents, glossing agents, hydrophobizing and oleophobicizing agents, moth protection and refatting agents, and conditioning agents can be added to the solvent. The goods should not absorb more than 30% of their own weight in the course of the cleaning time. The cleaning time during which the material to be treated is moved in the rotating drum depends on the degree of soiling and the type of material to be cleaned and, based on experience, is approximately 10 to 20 minutes. The goods are then spun off and the spun-off cleaning liquor is pumped off into the still or into the storage tank. This is followed by drying, during which the solvent is recovered at a temperature between 15 and 45 ° C (measured at the drum outlet in the gas space). After drying is complete, the goods and sponges can be removed from the drum dry and odorless. It is advisable to suck the sponges out of the drum into a container using a special device before drying the goods. Depending on the degree of soiling, the soiled sponges are cleaned from time to time in a solvent bath of the cleaning machine, so that they can be used again.

During this cleaning operation, the sponges of the quality according to the invention release only part of the absorbed solvent into the items to be cleaned, even with different upsetting. This amount of solvent is sufficient to loosen the dirt in the goods. The dirt is removed by rubbing the cleaning material on the surface of the solvent-containing sponges, which absorb the detached dirt. Adding surfactants, greasing agents etc. can improve cleaning failure, the suppleness of the leather and the appearance of the fur hair.

Since the fur in the treatment in a solvent liquor is degreased too much due to its special dressing even when adding greasing agents and can be damaged, a material must be added when cleaning the drum that has a special affinity for the solvent. Such a material thus serves as a solvent buffer. The polyurethane foams used according to the invention with the specified density give less than 20% of the amount of solvent absorbed to the goods to be cleaned, thereby avoiding damage to sensitive textile and leather material due to excessive extraction.

This cleaning process is suitable for leather and fur clothing as well as for other types of textiles that are damaged during treatment in a solvent bath. These include, for example, garments made of soft PVC, the plasticizer of which is largely extracted from the solvents used in textile cleaning, which makes the fabric hard, brittle and cracked. This method is also suitable for degreasing fur skins during the dressing process.

Example 1 (comparative example )

100 parts by weight of a glycerol / propylene oxide / ethylene oxide addition compound (average molecular weight 3500, hydroxyl number 47, proportion of primary hydroxyl groups 20 mol%) were mixed with 2.5 parts by weight of water and 0.8 part by weight of foam stabilizer based on polysiloxane , 0.36 part by weight of a mixture of 33% by weight of triethylene diamine and 67% by weight of dipropylene glycol, 0.18 part by weight of tin (II) octoate and 35 parts by weight of tolylene diisocyanate are mixed intimately and in foamed in a paper form. The result is a typical soft elastic foam with a density of 39 kg / m³.

Example 2

100 parts by weight of a glycerol-propylene oxide-ethylene oxide addition compound of medium equivalent weight 450 (hydroxyl number = 125) with a proportion of primary hydroxyl groups of 60 mol%, 8 parts by weight of 1,4-butanediol, 0.5 Parts by weight of water, 10 parts by weight of trichlorofluoromethane, 0.5 part by weight of foam stabilizer (® Tegostab B 4113 from Goldschmidt AG), 0.6 part by weight of a 33% solution of triethylene diamine in dipropylene glycol, 05 parts by weight of dibutyl tin dilaurate were intimately mixed with a reaction product of 72% by weight tolylene diisocyanate 80/20 and 28% by weight polyethylene glycol of average molecular weight 600 and brought to foaming in a prepared paper form. After the foaming is complete, the foam is cured in an oven at 70 ° C. for 15 minutes, and the cooled foam is cut into correspondingly small parts. The result is an open-cell, soft, elastic foam with a density of 90 kg / m³.

A =

Verzweigtes Polyol der OH-Zahl 75 mit Handelsnamen ® Tercarol L 200 (Lieferant Carbochim, B - 7340 Tertre)

B =

1,4-Butandiol

C =

Glycerin

D =

Wasser

E =

33 %ige Lösung von Triethylendiamin in Dipropylenglykol

F =

^(R) Tegostab B 4113 (Lieferant Goldschmidt AG, D - 4200 Essen)

G =

Dibutylzinndilaurat

H =

Dibutylzinndiversatat

K =

Trichlorfluormethan

L =

Reaktionsprodukt aus 72 Gew.-% Toluylendiisocyanat 80/20 und 28 Gew.-% Polyethylenglykol von mittleren Molekulargewicht 600

In der folgenden Tabelle 2 wird gezeigt, daß je nach Rezeptur ein unterschiedlich hoher "Verformungsdruck" der Schwämme resultiert, was sich aus den Meßwerten der Stauchhärte von 10 bis 50 % Verformung zeigt. Je nach Art des zu reinigenden Materials kann die entsprechende Schaumhärte gewählt werden, wobei zur Erreichung des Reinigungseffektes sich die Schwämme bis zu 50 % verformen dürfen. Der progressive Verformungsdruck von 10 % auf 50 % ist dabei von Vorteil

• einmal für die schonende Reinigungswirkung bei Reibung und geringer Verformung
• zum anderen für die Belastbarkeit der Schwämme ohne deren vollständige Zusammendrückung, was den Austritt des Lösemittels aus den Schwämmen zur Folge hätte.

Further sponges according to the invention of different compression hardness can be produced according to the following Examples 3 to 6, in the same way as with Bei game 2 was worked. The recipes summarized in Table 1 are based on the following raw materials:

A =

Branched polyol of OH number 75 with trade name ® Tercarol L 200 (supplier Carbochim, B - 7340 Tertre)

B =

1,4-butanediol

C =

Glycerin

D =

water

E =

33% solution of triethylenediamine in dipropylene glycol

F =

^(R) Tegostab B 4113 (supplier Goldschmidt AG, D - 4200 Essen)

G =

Dibutyltin dilaurate

H =

Dibutyltin Diversat

K =

Trichlorofluoromethane

L =

Reaction product of 72% by weight tolylene diisocyanate 80/20 and 28% by weight polyethylene glycol of average molecular weight 600

In the following Table 2 it is shown that depending on the recipe a different "deformation pressure" of the sponges results, which can be seen from the measured values of the compression hardness of 10 to 50% deformation. Depending on the type of material to be cleaned, the appropriate foam hardness can be selected, with the sponges being allowed to deform by up to 50% to achieve the cleaning effect. The progressive deformation pressure from 10% to 50% is an advantage

• once for the gentle cleaning effect in the case of friction and low deformation
• on the other hand, for the resilience of the sponges without their complete compression, which would result in the solvent escaping from the sponges.

In contrast to the foams according to the invention, the normal flexible polyurethane foam according to Example 1 is hardly progressive with regard to the deformation pressure, because a deformation of 50% is also possible in the load range of 10% deformation, at which the cleaning effect can start due to the frictional forces, which would promote the leakage of solvent from the sponge and would be harmful to the items to be cleaned.

• 1. Sägemehl in der Qualität, wie es zum Läuterungsverfahren für die Pelzreinigung verwendet wird.
• 2. Typischer Polyurethan-Weichschaum, hergestellt gemäß Beispiel 1 (Vergleichsbeispiel),
• 3. Offenzelliger Polyurethan-Weichschaum, hergestellt gemäß Beispiel 2 (erfindungsgemäßer Schaum).

The following test will demonstrate the particular suitability of the polyurethane foam with the specified density for cleaning fur. Three different materials were tested for their affinity for the solvents trichlorofluoromethane (FIG. 1), 1,1,2-trichloro-1,2,2-trifluoroethane (FIG. 2) and tetrachloroethene (FIG. 3):

• 1. Sawdust of the quality used for the fur cleaning process.
• 2. Typical flexible polyurethane foam, produced according to Example 1 (comparative example),
• 3. Open-celled flexible polyurethane foam, produced according to Example 2 (foam according to the invention).

• 1. Versuchsmaterial 1/2 Stunde im Trockenschrank bei 20°C trocknen und 1/2 Stunde im Exsikkator abkühlen.
• 2. Pelzstückchen aus Persianerfell mit den Abmessungen von 5 x 5 cm und ein Säckchen mit 10 Stahlkugeln in verschraubbaren Linitest-Becher legen.
• 3. Schwämme mit einer Kantenlänge von 5 x 2,5 x 1,5 cm (Volumen 18,75 cm³ ) bzw. 8 cm³ Sägemehl in einem Baumwollsäckchen mit dem betreffenden Lösemittel tränken.
• 4. Lösemittel 10 Sekunden ablaufen lassen, Schwämme bzw. Säckchen mit Sägemehl wiegen. Beim Sägemehl das Gewicht des trocknen bzw. nassen Säckchens später abziehen.
• 5. 10 Schwämme sowie Säckchen getrennt nach Qualität mit den Pelzstücken und den Stahlkugeln im Säckchen im Linitest 10 Minuten rotieren lassen.
• 6. Nach 10 Minuten Schwämme bzw. Sägemehlsäckchen und die Pelzstückchen einzeln herausnehmen und wiegen.
• 7. Versuche mit 20 und 30 Minuten Behandlungszeit wiederholen.

The distribution of the solvents between these carrier materials and fur was examined in the ^(R) Linitest with high-temperature insert containers as follows:

• 1. Dry the test material in the drying cabinet at 20 ° C for 1/2 hour and cool in the desiccator for 1/2 hour.
• 2. Place pieces of Persian fur with the dimensions of 5 x 5 cm and a sachet with 10 steel balls in a screwable Linitest cup.
• 3. Soak sponges with an edge length of 5 x 2.5 x 1.5 cm (volume 18.75 cm³) or 8 cm³ sawdust in a cotton bag with the solvent in question.
• 4. Let the solvent run off for 10 seconds, weigh sponges or sachets with sawdust. With sawdust, remove the weight of the dry or wet bag later.
• 5. Rotate 10 sponges and sachets, separated by quality, with the fur pieces and the steel balls in the sachet in the Linitest for 10 minutes.
• 6. After 10 minutes, take out sponges or bags of sawdust and the pieces of fur individually and weigh.
• 7. Repeat the tests with a treatment time of 20 and 30 minutes.

The values obtained here are shown in the diagrams in FIGS. 1-3. The curves S₁, S₂ and S₃ represent the percentage of residual solvent as measured for the carrier substances PUR foam according to Example 2 (S₁), PUR foam according to Example 1 (S₂) and sawdust (S₃). The curves P₁, P₂ and P₃ show the corresponding residual amounts in the fur. The closer the corresponding curve pairs of carrier substances and fur approach, the greater the solvent exchange. So with tetrachlorethylene between sawdust and fur the unwanted solvent compensation takes place, ie the curves S₃ and P₃ intersect before 30 minutes (see Figure 3). In contrast, in the presence of the foam according to the invention according to Example 2, the fur does not absorb more than 10% of the two fluorocarbons (see FIGS. 1 and 2) and not more than 20% of the total amount of solvent in the case of tetrachloroethene (see FIG. 3). All three diagrams clearly show that the distance between the pairs of curves S₁ and P₁ is greatest. The solvent exchange between the polyurethane foam according to Example 1 and the fur lies between the values for the foam according to the invention, which releases only small amounts of solvent, and the values for the sawdust. The curve pairs S₂ and P₂ show in all three diagrams that the fur in the presence of the polyurethane foam according to Example 1 takes up more than 20% of the total amount of solvent. These experiments show that the polyurethane foams with the higher density, as used according to the invention, do not release the predominant proportion of the solvent taken up to the fur pieces, while the solvent retention of typical soft foam sponges (according to Example 1) and of sawdust is considerably lower.

Abrasion resistance test

Sponges of the two foam qualities to be tested were tested for abrasion resistance both under practical conditions and on a laboratory scale. In the practical test, sponges in the shape of a cube with an edge length of 5 cm were cleaned 12 times in a HFC cleaning machine. The cleaning time was 12 minutes per treatment. 10 sponges per quality were also moved with FKW 113 and a bag with 10 steel balls in the Linitest for 5 hours. The abrasion resistance of the foam according to Example 2 was better than that of the foam according to Example 1.

Application example for fur cleaning

15 kg sponges with a diameter of 5 cm, produced according to Example 2, were poured into a cleaning machine with a drum content of approximately 1000 l. After closing the loading door, solvents were sprayed into the drum via nozzles. The weight of the solvent absorbed was about twice the weight of the sponges. Then the loading door was opened again and the fur clothing (40 kg) was placed in the drum with the drum suction switched on. The fill factor (kg goods: 1 drum volume) was 1:25. The cleaning time was 10 to 20 minutes. The fur clothing was then spun off and the spun-off cleaning liquor was pumped off into the still or into the storage tank. This is followed by drying, during which the solvent was recovered at a temperature between 15 and 45 ° C (measured at the drum outlet in the gas space). After drying was completed, fur clothing and sponges were removed from the drum dry and odorless.

Application example for cleaning synthetic leather made of soft PVC

8 kg sponges with a diameter of 5 cm, produced according to Example 2, were poured into a cleaning machine with a drum content of approximately 500 l. After closing the loading door, solvents were sprayed into the drum via nozzles. The weight of the solvent absorbed was about twice the weight of the sponges. Then the loading door was opened again and the clothes made of PVC synthetic leather were inserted into the drum with the drum suction switched on. The filling factor (kg of goods: 1 drum volume) was approximately 1:25. To increase the cleaning effect, hard-tough sponges were added to the material to be treated. The material to be treated should be in the course of cleaning not take up more than 30% of their own weight. Otherwise, the procedure was as described in the previous example for fur cleaning.

Claims (3)

1. A process for cleaning textiles, furs and leathers and for degreasing furs during the dressing process, which comprises treating these materials with pieces of open-celled polyurethane foam from 60 to 120 kg/m³ in density which have been impregnated with halocarbons.
2. The process of claim 1, wherein pieces are used of a polyurethane foam obtained by reacting a mixture of polyalkylene glycol having an equivalent weight of from 200 to 2000 and a polyhydroxy compound having an equivalent weight of from 30 to 100 with an isocyanato-containing intermediate formed from a polyisocyanate and a polyalkylene glycol and having an equivalent weight of from 50 to 500, preferably 300.
3. The process of claim 1, wherein a surfactant, a fatliquoring agent or other auxiliary is used in addition.

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