EP0213480B1 - Method of water-proofing leather and furs - Google Patents

Description

The invention relates to a process for hydrophobizing leather and furs with a silicone oil and the salt of an N- (C _s -C _2o -acyl) amino acid as an emulsifier for the silicone oil, which is carried out in the aqueous phase during or after retanning, and the use of salts of N- (C _s -C ₂ o-acyl) amino acids for emulsifying silicone oil in the aqueous phase in the waterproofing of leather and furs and the mixtures used.

A wide variety of methods for waterproofing are known for leather and furs. For example, silicone oils are also used for this finishing stage. The polysiloxanes used are always dissolved in organic solvents such as gasoline or chlorinated hydrocarbons. Disadvantages when working with these solvents are the harmful and polluting effects as well as the fire risk when using gasoline. The hydrophobization with the help of organic solvents also means an additional work step and thus a considerably increased effort.

N-acylamino acids, especially fatty acid sarcosides, e.g. N-oleoyl sarcosine, in the form of their salts, are known as emulsifiers for paraffins and waxes, which can also be used, for example, in the waterproofing of leather. The effects that can be achieved with waxes and paraffins are not always sufficient for today's high requirements and are usually supplemented by a separate post-hydrophobic treatment with, for example, fluorochemicals or silicone oils that are applied from the organic phase.

The object of the invention is to develop a process for hydrophobizing leather and furs, in which organic solvents are not necessary and can be rendered hydrophobic with a silicone oil in the aqueous phase, the technical application effect on leather and furs being at least equivalent to that of silicone oils from organic Solvents should be.

The solution to the problem consists in a process for waterproofing leather and furs, in which a silicone oil with the salt of an N- (C9-C2o-Acyi) amino acid as an emulsifier in an aqueous liquor onto the leather or furs to be refined during or after of retanning.

The invention is based on the observation that N- (C _s -C _2o- acyl) amino acids, in particular fatty acid sarcosides, in the form of their salts are excellent emulsifiers for silicone oils, so that the use in the waterproofing of leather and furs in aqueous liquors is first demonstrated can be. Sufficiently stable aqueous emulsions of silicone oils can only be achieved with the indicated emulsifier without additional aids for the purposes of use. This was all the more surprising since the emulsifiers to be used according to the invention can also be absorbed onto the leather during use, so that one could have expected the emulsion to be destabilized.

• a) die wäßrige Emulsion eines Siliconöls, bestehend aus 15 bis 90 Gew.-% Siliconöl, 5 bis 30 Gew.-% eines Salzes einer Aminosäure mit 2 bis 6 C-Atomen und mit dem Acylrest einer gesättigten oder ungesättigten Fettsäure mit 9 bis 20 C-Atomen am Aminstickstoffatom, das gegebenenfalls zusätzlich durch Methyl substituiert ist, und wenigstens 5 bis Rest zu 100 Gew.-% Wasser, die mit einem Alkalihydroxid, Ammoniak oder einem Alkanolamin auf einen pH-Wert von 5 bis 12, vorzugsweise 7 bis 10, eingestellt ist, oder
• b) das wasserfreie Gemisch aus 70 bis 90 Gew.-% eines Siliconöls und 10 bis 30 Gew.-% eines Alkanolaminsalzes einer Aminosäure mit 2 bis 6 C-Atomen und mit dem Acylrest einer gesättigten oder ungesättigten Fettsäure mit 9 bis 20 C-Atomen am Aminstickstoffatom, das gegebenenfalls zusätzlich durch Methyl substituiert sein kann,

The invention relates to a process for waterproofing leather and furs with a silicone oil in the presence of a salt of an N- (C _s -C _2o -acyl) amino acid as an emulsifier, which is characterized in that

• a) the aqueous emulsion of a silicone oil consisting of 15 to 90 wt .-% silicone oil, 5 to 30 wt .-% of a salt of an amino acid with 2 to 6 carbon atoms and with the acyl residue of a saturated or unsaturated fatty acid with 9 to 20 C atoms on the amine nitrogen atom, which is optionally additionally substituted by methyl, and at least 5 to the rest of 100% by weight of water, which are adjusted to a pH of 5 to 12, preferably 7 to 10, using an alkali metal hydroxide, ammonia or an alkanolamine , is set, or
• b) the anhydrous mixture of 70 to 90 wt .-% of a silicone oil and 10 to 30 wt .-% of an alkanolamine salt of an amino acid with 2 to 6 carbon atoms and with the acyl residue of a saturated or unsaturated fatty acid with 9 to 20 carbon atoms on the amine nitrogen atom, which may optionally be additionally substituted by methyl,

in an amount of 0.5 to 20% by weight, based on the shaved weight of the leather or wet weight of the furs, in an aqueous liquor at a pH of 4.5 to 8.0 on the leather or furs to be treated during or after retanning, and then adjusted to a pH of 3.0 to 5.0 and, if appropriate, aftertreated in the aqueous solution with a metal salt which is customary in tannery.

The invention also relates to the use of amino acids with 2 to 6 carbon atoms and with the acyl residue of a saturated or unsaturated fatty acid with 9 to 20 carbon atoms on the amine nitrogen atom, which may optionally be substituted by methyl, in the form of an alkali metal, Ammonium or alkanolamine salt for emulsifying silicone oil in the aqueous phase in the waterproofing of leather and furs during or after retanning.

The invention thus also relates to the use of the aqueous emulsion a) or of the anhydrous mixture b) of the composition given above in aqueous liquors for hydrophobicizing leather or furs during or after retanning in an amount of 0.5 to 20% by weight, based on the fold weight of the leather or wet weight of the fur.

The particular advantage of the process according to the invention is that, in a simple procedure while avoiding organic solvents, an emulsifier for the silicone oil has been found which emulsifies the silicone oil sufficiently so that the silicone oil can penetrate the leather finally by adding acid and optionally a polyvalent metal salt, the N-acylamino acid salt used is rendered ineffective as an emulsifier, so that the full hydrophobizing action of the silicone oil comes into play. It should be emphasized that the use of organic solvents and additional auxiliaries, for example nonionic emulsifiers, can be avoided.

As the silicone oils, the commercial silicone oils having viscosities from 30 to 1.000 _mPa.s, preferably 80 to 500 m ^p as, into consideration. Such silicone oils can be readily used by those skilled in the art, for example Römpps Chemie-Lexikon, 7th edition, Stuttgart, 1975, pp. 3223ff, or Ullmanns Enzyklopadie der techn. Chemie, 4th ed., 1982, volume 21, pp. 512ff. For example, silicone oils are suitable in which the remaining valences of silicon are saturated by hydrocarbon radicals, in particular methyl, but also ethyl, propyl or phenyl. Very particular preference is given to those silicone oils which in their hydrocarbon radicals carry organofunctional groups such as amino, mercapto or carboxyl groups. Because of these functional groups, they are easier to emulsify and thus better bind to the leather fibers. The viscosities given are a practical measure of the molecular weights, which can often only be determined with great effort.

Preferred silicone oils are dimethylpolysiloxanes with a viscosity of 80 to 110 mPa _' s, phenylmethyl polysiloxanes with a viscosity of 85 to 120 m ^p as, dimethylpolysiloxanes with amino groups as reactive groups, characterized by an amine number of about 0.8 to 1.0 and a viscosity of 30 to 50 mPa.s, and dimethylpolysiloxanes with carboxyl groups as reactive groups, on average with 2 to 10 carboxyl groups per molecule.

Dimethylpolysiloxanes, the methyl groups of which are partially replaced by mercaptopropyl (-CH2-CH2-CH2-SH) or aminopropyl groups (-CH ₂ -CH ₂ -CH ₂ -NH ₂ ) as reactive groups, are very particularly preferred. As a rule, 1 to 5%, preferably approx. 3%, of the methyl groups in the chain are replaced by these reactive substituents. These are commercially available dimethylpolysiloxanes with terminal -Si (CH ₃ ) ₃ groups, which can be characterized by a viscosity range from 130 to 200, preferably 145 to 180 m ^p as. The preferred and particularly preferred silicone oils are commercially available products.

Of the N- (C ₉ -C ₂₀ -acyl) amino acids with 2 to 6 C atoms, those with 2 to 4 C atoms, with the amino group in the a-position to the carboxyl group and those on the amine nitrogen atom are additionally substituted by a methyl group are preferred. Of these, the fatty acid sarcosides of saturated or unsaturated fatty acids with 9 to 20, preferably 16 to 18, carbon atoms have a particularly superior effect.

Suitable salts are the alkali metal salts, in particular sodium or potassium, the ammonium salts or salts of a mono-, di- or trialkanolamine having 2 to 4 carbon atoms in the alkanol radical, in particular mono-, di- or triethanolamine.

The particularly preferred sarcoside is oleic acid sarcoside or N-oleoyl sarcosine (medialanic acid). Furthermore, the N-stearoyl sarcosine, N-lauroyl sarcosine and N-isononanoyl sarcosine are to be emphasized, in each case in the form of the salts mentioned above.

The silicone oil and the salt of N-acylamino acid are advantageously in the form of an aqueous emulsion as a concentrate, consisting of 15 to 90% by weight of an above-mentioned silicone oil, 5 to 30% by weight of an above-mentioned salt of an N- (C _e -C ₂ o-acyl) amino acid and at least 5 to the rest of 100% by weight of water, a pH of 5 to 12, preferably 7 to 10, having been set using an alkali metal hydroxide, ammonia or an alkanolamine. The preferred concentrate contains 30 to 60% by weight of silicone oil, 5 to 30% by weight of salt of an N- (C ₉ -C ₂₀ -acyl) amino acid and 65 to 10% by weight of water, the pH value has been set to a very preferred range of 7.5 to 8.5.

In a further embodiment, an anhydrous concentrate consisting of 70 to 90% by weight of silicone oil and 10 to 30% by weight of one of the N-acylamino acids defined above in the form of a mono-, di- or trialkanolamine salt is used.

When such an anhydrous mixture is added to the aqueous liquor, the silicone oil in the aqueous phase is automatically emulsified by the salt used.

It should be noted that the aqueous emulsion defined above is preferred as the concentrate to be used.

The hydrophobization according to the invention can be combined with a known hydrophobizing agent, for example based on a paraffin or wax emulsion, i.e. at the same time or following a hydrophobization which is customary in aqueous liquors. A significant improvement in the water repellency effects is achieved.

The concentrates described above can, based on the total weight of the mixture, additionally 5 to 45, preferably 10 to 30,% by weight solid and / or liquid paraffin, for example paraffin with a melting point of 20 to 100 _° C., paraffin oil or white oil, a natural fat or oil, such as fish oil or bone oil, or a synthetic or natural wax, such as polyethylene wax, polyisobutylene wax, beeswax or carnauba wax, the weight ratio of silicone oil to paraffin expediently not exceeding the value of 1: 1. Solid paraffin with a melting point between 40 and 60 _° C. and white oil are particularly preferred for such a combination. The specified amounts of paraffin, fats, oils or waxes are from the Kon concentrates easily recorded.

In practical use, an above-mentioned concentrate, based on the shaved weight of the leather or wet weight of the furs, in an amount of 0.5 to 20% by weight, preferably 2 to 10% by weight, optionally together with dyes, during or after the retanning .-% used. The concentrate used is expediently diluted with water in a ratio of 1: 2 to 1: 5 and added to the working liquor.

The hydrophobization according to the invention can also be carried out in two stages during and after retanning. Useful tanning agents for retanning are vegetable tanning agents and synthetic tanning agents, for example based on phenolsulfonic acid-formaldehyde condensates. Suitable dyes which can be used simultaneously are, for example, the customary acidic, substantive or basic aniline dyes.

The actual hydrophobization according to the invention during or after retanning is carried out by milling in a suitable device in a conventional manner: that is, with liquor lengths of 50 to 2,000%, preferably 100 to 400%, based on the shaved weight of the leather or wet weight of the furs, temperatures of 20 to 60 _° C, preferably 35 to 50 _° C, with the pH values usually being between 4.5 and 8.0, preferably 4.8 to 5.5, at the beginning. In general, the hydrophobization is completed in a time between 20 to 240, preferably 30 to 120 minutes.

At the end of the hydrophobization, the emulsifier is fixed with acid, preferably formic acid, by adjusting a pH of 3.0 to 5.0, preferably 3.8 to 4.0.

The effect of the hydrophobization can be enhanced by an aftertreatment with a tetravalent, normal or tetravalent metal salt, in particular with a basic chromium sulfate, with aluminum sulfate, zirconium, titanium sulfate, calcium chloride or magnesium sulfate.

Of the salts mentioned, 0.5 to 5% by weight, preferably 1 to 2% by weight, is expediently used, based on the shaved weight of the leather or wet weight of the furs. Of the specified salts, basic chromium sulfate and aluminum sulfate are preferred.

Examples

Parts are parts by weight, percentages relate to the weight, unless stated otherwise.

A. Production of silicone oil mixtures to be used according to the invention example 1

49.2 parts of a dimethylpolysiloxane, in which 3% of the methyl groups in the chain are replaced by mercaptopropyl, with a viscosity of 150 m ^p as and 9.8 parts of N-oleoyl-sarcosine (oleic acid sarcoside) are mixed with stirring and to 60 _° C warmed. A mixture of 37.2 parts of water and 1.8 parts of 50% strength aqueous sodium hydroxide solution, heated to 60 _° C., is then slowly added with stirring. The complete conversion to the sodium salt is shown by the fact that a constant pH is established. The pH of the mixture is then adjusted to 7.5 to 8.0. The finished mixture is allowed to cool with stirring.

Example 2

79.0 parts of a dimethylpolysiloxane, in which 3% of the methyl groups in the chain are replaced by mercaptopropyl, with a viscosity of 150 m ^p as and 15 parts of N-oleoyl-sarcosine are mixed and the mixture is heated to 60 _° C. with stirring . Then 6.0 parts of diethanolamine (100%) are added at 60 ° C. with stirring. The finished mixture is allowed to cool with stirring.

Example 3

41.3 parts water and 3.7 parts of aqueous 25% sodium hydroxide solution are mixed and heated to 60 _° C. In the dilute sodium hydroxide solution, a mixture previously heated to 60 _° C of 30.0 parts of a dimethylpolysiloxane are in which 3% of the methyl groups are replaced by mercaptopropyl, having a viscosity of 180 m ^p as, 6.0 parts of paraffin wax with a melting point of 52 to 54 _° C, 9.5 parts of white oil and 9.5 parts of N-oleoyl sarcosine stirred. The mixture is stirred at 60 _° C until the pH remains constant. The pH of the mixture is then adjusted to 7.5 to 8.0. The mixture is cooled with stirring.

Example 4

200 parts of the dimethylpolysiloxane characterized in Example 1 and 40 parts of N-stearoyl sarcosine

(Stearic acid sarcoside) are mixed with stirring and heated to 60 _° C. A mixture of 160 parts of water and 8 parts of 50% strength aqueous sodium hydroxide solution, heated to 60 _° C., is then slowly added with stirring. After adjusting the pH to 7.5-8 with 50% sodium hydroxide solution, the mixture is allowed to cool with stirring.

Example 5

200 parts of the dimethylpolysiloxane characterized in Example 1 and 40 parts of N-lauroyl sarcosine (Laurinsäuresarkosid) are mixed with stirring and heated to 60 _° C. A mixture of 160 parts of water and 8 parts of 50% strength aqueous sodium hydroxide solution, heated to 60 _° C., is then slowly added with stirring. After adjusting the pH to 7.5-8 with 50% sodium hydroxide solution, the mixture is allowed to cool with stirring.

Example 6

200 parts of the dimethylpolysiloxane characterized in Example 1 and 40 parts of N-isononanoyl-sarcosine (isononanoic acid sarcoside) are mixed with stirring and heated to 60 _° C. A mixture of 160 parts of water and 12 parts of 50% strength aqueous sodium hydroxide solution, heated to 60 _° C., is then slowly added with stirring. The mixture is allowed to cool with stirring.

Example 7

160 parts of the dimethylpolysiloxane characterized in Example 1 and 40 parts of N-oleyl sarcosine (oleic acid sarcoside) are mixed with stirring and heated to 60 _° C. Then a mixture of 160 parts of water and 17.5 parts of triethanolamine heated to 60 ° C. is slowly added with stirring. The mixture is allowed to cool with stirring.

Examples 8 to 11

Production of silicone oil emulsions:

50.0 parts of a commercially available according to the invention to be used in the polysiloxane are mixed with 10.0 parts N-oleoyl-sarcosine, with stirring and heated to 60 _° C. Then a mixture of 36 parts of water and 4 parts of 25% aqueous sodium hydroxide solution heated to 60 _° C. is slowly added with stirring. The complete conversion to the sodium salt is achieved by stirring until the pH is constant. The pH of the mixture is then adjusted to 7.8 to 8.0 and cooled to room temperature with stirring.

A procedure in which the mixture of water and sodium hydroxide solution is initially introduced and the mixture of silicone oil and N-oleoyl-sarcosine is added with stirring leads to the same result.

The commercially available polysiloxane used in Example 8 was a dimethylpolysiloxane with a viscosity of about 95 mPa _' s, in Example 9 a phenylmethyl polysiloxane with a viscosity of about 95 mPa.s, in Example 10 an amino-functional dimethylpolysiloxane with an amine number of about 0.8 to 1.0 and a viscosity of 30 to 50 mPa _' s and in Example 11 a dimethylpolysiloxane with 4 carboxyl groups in the molecule.

B. Applications Application example Diel A

Chromium pre-tanned cowhide leather with a fold thickness of 2.2 mm, which has been deacidified to a pH value of 5.0 to 6.0, based on the fold weight, with 5% by weight of commercially available mimosa extract and 3% by weight of a commercially available synthetic tanning agent based on phenolsulfonic acid-formaldehyde condensate, 1% by weight of a commercially available aniline dye and 5% by weight of the silicone oil emulsion specified in Example 1, drummed at 40 _° C. in the tanning drum for 1.5 hours, the pH of the treatment liquor being 100% is 5.2 to 5.5.

It is then acidified to a pH of 4.5 with 85% formic acid, drummed for 30 minutes and then washed with water at 40 _° C. for 10 minutes.

In the fresh bath of 100% water and 40 _° C., a further 3% by weight, based on the shaved weight, of the silicone emulsion specified in Example 1 is rolled into the leather within 30 minutes. It is acidified with 85% formic acid to a pH of 3.8 to 4.0 and with 2% by weight of a commercially available chrome tanning agent (Cr ₂ 0s content of 25% and a basicity of 33%) for 90 minutes fixed at 40 _° C. The leathers are then washed, mechanically stretched and dried.

The test in the Bally penetrometer at 15% compression showed the following values:

Example of use B

Chromium-tanned and deacidified to a pH value of 5.0 to 6.0, each based on the shaved weight of the leather, with 5% by weight of chestnut wood extract, 3% by weight of a commercially available synthetic tanning agent based on naphthalenesulfonic acid-formaldehyde Condensate, 1% by weight of aniline dye and a mixture of 6% of a commercially available hydrophobizing agent for leather based on a paraffin emulsion and 3% by weight of silicone oil emulsion according to Example 2, drummed for 2 hours. It is then acidified to a pH of 3.8 to 4.0 with formic acid and fixed for a further 90 min with a commercially available chrome tanning agent (chromium oxide content approx. 25%, basicity approx. 33%). After washing out, the usual drying takes place.

The test in the Bally penetrometer at 15% compression showed the following values:

Example of use C

After the deacidification to pH 5.0 to 6.0, chrome-tanned cowhide (wet blue) is used for retanning, in each case based on the shaved weight of the leather, 7.5% by weight of a mixture of vegetable and synthetic commercial tannins based on naphthalenesulfonic acid. Formaldehyde condensate, 1.5% by weight of a commercially available aniline dye and 7% by weight of a conventional water repellent for leather based on a paraffin emulsion, drummed for 60 minutes and then for a further 30 minutes with 3% by weight of the silicone oil emulsion Example 1 drummed in the barrel. With further walking for 30 minutes, the mixture is acidified to a pH of 4.0 with formic acid and fixed with 1.5% by weight of commercially available chromium tanning agent within 90 minutes.

The leather is rinsed and dried as usual.

The test in the Bally penetrometer at 15% compression showed the following values:

Application example D

The wetblue leather deacidified to a pH of 5.0 to 6.0 with commercially available deacidifying agents are retanned, dyed, as indicated in Example A, and not, based on the shaved weight, 8% by weight of a commercially available, respectively - Greaser mixture with a hydrophobic effect greased, acidified to a pH of 4.0 and rinsed.

The mixture is then drummed in fresh liquor (100%, 40 _° C.) for 30 minutes with 4% by weight of the silicone oil emulsion described in Example 3 with paraffin and white oil and fixed with 1.5% by weight of commercially available chromium tanning agent for 60 minutes.

After washing and stretching, the usual drying takes place.

The following values were found when tested in a Bally penetrometer at 15% compression:

Application example E

The chrome-tanned leathers deacidified to a pH of 5.0 to 6.0 are retanned as in Example A with, based on the shaved weight of the leather, 7% by weight of a mixture of commercially available vegetable and synthetic tanning agents based on phenol condensate, dyed with 1.2% by weight of aniline dye and greased with 5% by weight of commercially available, non-hydrophobic grease licker for 40 min.

The mixture is then drummed with a mixture of 3% by weight of the silicone oil emulsion specified in Example 1 and 3% by weight of a commercially available hydrophobicizing agent based on paraffin emulsion, acidified to pH 3.8 to 4.0, for 30 minutes, with 5 wt .-% of a commercial aluminum salt min fixed (Al ₂ SO _{4) 3} .18 H ₂ 0 60, washed, and stretched out as usual and dried.

The test in the Bally penetrometer at 15% compression showed the following values:

The tests carried out in the Bally penetrometer show significantly improved water resistance in the dynamic test up to the passage of the first drop of water and a considerable reduction in the water absorption of the leather compared to the previously usual hydrophobization process.

Example of use F

The procedure is as in Example A.

Testing the treated leather in a Bally penetrometer at 15% compression gave the following values:

Claims (4)

1. A process for waterproofing leather and skins with a silicone oil in the presence of a salt of an N-(Cs-C₂o-acyl)-amino acid as an emulsifier, wherein

a) an aqueous emulsion of a silicone oil, consisting of from 15 to 90% by weight of silicone oil, from 5 to 30% by weight of a salt of an amino acid of 2 to 6 car bon atoms which has an acyl radical of a saturated or unsaturated fatty acid of 9 to 20 carbon atoms on the amine nitrogen atom, which may additionally be substituted by methyl, and from not less than 5% by weight to the remainder to 100% by weight of water, the emulsion being brought to pH 5-12, with an alkali metal hydroxide, ammonia or an alkanolamine, or

b) an anhydrous mixture of from 70 to 90% weight of a silicone oil and from 10 to 30% by weight of an alkanolamine salt of an amino acid of 2 to 6 carbon atoms which has an acyl radical of a saturated or un- saturate fatty acid of 9 to 20 carbon atoms on the amine nitrag atom, which may additionally be substituted by methyl,

in an amount of from 0,5 to 20% by weight, based on the shaved weight of the leather or wet weight of the skins, is allowed to act on the leather or skins to be treated, in an aqueous liquor at pH 4,5-8,0, during or after retanning, after which the pH is brought to 3,0-5,0 and, if required, the leather or skins are aftertreated in the aqueous solution with a divalent, trivalent or tetravalent metal salt conventionally used in tanning.

2. An emulsion for use in waterproofing leather and skins in an aqueous liquor during or after retanning, con sisting of from 15 to 90% by weight of silicone oil, from 5 to 30% by weight of a salt of an amino acid of 2 to 6 carbon atoms which has an acyl radical of a saturated or unsaturated fatty acid of 9 to 20 carbon atoms on the amine nitrogen atom, which may additionally be substituted by methyl, and from not less than 5% by weight to the remainder to 100% by weight of water, and the pH being brought to 5-12 with an alkali metal hydroxide, ammonia or an alkanolamine.

3. A mixture for use in waterproofing leather or skins in an aqueous liquor during or after retanning, consisting of from 70 to 90% by weight of a silicone oil and from 10 to 30% by weight of an alkanolamine salt of an amino acid of 2 to 6 carbon atoms possessing an acyl radical of a saturated or unsaturated fatty acid of 9 to 20 carbon atoms on the amine nitrogen atom, which may additionally be substituted by methyl.

4. Use of the aquous emulsion a) or the anhydrous mixture b) defined in claim 1 in waterproofing leather and skins during or after retanning.