EP0280152B1 - Water-proofing agent for leather - Google Patents

Description

The present invention relates to aminosiloxane or aminopolysiloxane-containing waterproofing agents for leather.

The waterproofing or repelling (waterproofing) of leather during or at the end of wet dressing and in whole or in part instead of greasing (also called barrel waterproofing) by treatment with preparations from aliphatic hydrocarbons, synthetic or natural oils and fats in combination with halogenated hydrocarbons and Suitable emulsifiers have been widely introduced in the leather industry in addition to other hydrophobing methods. A particular advantage of this barrel waterproofing on wet leather compared to waterproofing with silicones or fluorocarbons, which are applied to dry leather in a post-treatment mostly from water-immiscible organic solutions, is that they are used completely or at least partially in place of the customary licker lubrication can and in addition to the actual hydrophobization softens the leather (see e.g. preparations made from natural and / or synthetic fatty substances and waxes as well as paraffin hydrocarbons with emulsifiers, which are fixed by fixation with acids or metal salts and thereby lose their hydrophilicity).

It proves to be disadvantageous that, in the case of high demands on water resistance (up to several hours of water resistance) with high compression and bending stress, as is required, for example, for military, occupational safety and mountain boot leather, the barrel hydrophobization described above on wet leather alone is not sufficient, an additional treatment with silicones or fluorocarbons is required.

This additional aftertreatment can be carried out on dry leather with silicones or fluorocarbons, which are dissolved in organic solvents, or on wet leather with silicones, which are applied from an aqueous emulsion or alcoholic / aqueous dispersion. In order to avoid working with organic solvents, efforts are made to use aqueous or at least water-dilutable systems.

The aftertreatment with water-thinnable silicone emulsions or alcoholic / aqueous silicone dispersions now has the disadvantage that, in the case of silicone emulsions or hydrophilic alcohol, the hydrophilic emulsifiers are added to the leather Can adversely affect the fit and the effectiveness of the previous barrel hydrophobization and can only be compensated for by an increased supply.

From the older, not prepublished patent application EP-A 213 480 a method for hydrophobicizing leather with a silicone oil and the salt of an N-acylamino acid is known as an emulsifier. The particular suitability of mixtures containing aminosiloxanes and partially halogenated paraffins cannot be found in this document.

It was an object of the present invention to provide a hydrophobizing agent which does not have the above-mentioned disadvantages of the known processes and is also easy to handle.

• a) gesättigte und ungesättigte, aliphatische gerad- und verzweigt-kettige Kohlenwasserstoffe mit mindestens 10 C-Atomen, die teilweise halogeniert sind,
• b) Aminosiloxane, bzw. Aminopolysiloxane,
• c) Carboxylgruppen-haltige Emulgatoren, die durch Säuren oder mehrwertige Metallionen im Leder fixiert werden und dadurch ihre Hydrophilie verlieren, sowie gegebenenfalls
• d) Wasser.

The present invention thus relates to water repellents for leather containing the following constituents:

• a) saturated and unsaturated, aliphatic straight-chain and branched-chain hydrocarbons with at least 10 carbon atoms, some of which are halogenated,
• b) aminosiloxanes or aminopolysiloxanes,
• c) carboxyl group-containing emulsifiers which are fixed in the leather by acids or polyvalent metal ions and thereby lose their hydrophilicity, and if appropriate
• d) water.

It has surprisingly been found that the aftertreatment agents according to the invention give excellent results with regard to the waterproofness of the leather. The values for the water resistance are significantly higher than for the barrel hydrophobization with silicone-free Emulsions and are - without further aftertreatment - comparable to watertightness, which can usually be achieved by barrel hydrophobization (silicone-free) and additional aftertreatment with silicone and / or fluorocarbons.

The following are suitable as hydrocarbons (a):
At 20 ° C liquid, saturated and unsaturated straight and branched chain paraffins with C numbers from 10 to 24, preferably 15 to 20, and solid predominantly straight chain and saturated paraffins, preferably technical paraffin mixtures with softening points from 35 to 50 ° C, preferably 40 to 45 ° C and oil fractions of less than 5%.

The hydrocarbons described above are used together with halogen-containing, preferably chlorinated, hydrocarbons. Chlorine paraffins from straight-chain paraffins with 10 to 20, preferably 15-18, carbon atoms and 15 to 25, preferably 18 to 22% chlorine content have proven to be particularly suitable.

Particularly suitable emulsifiers c) are the amides of saturated and unsaturated, aliphatic carboxylic acids with 15 to 20, preferably 18 carbon atoms and alkylaminoacetic acids, preferably methylaminoacetic acid or their alkali, ammonium, mono-, di-, trialkylammonium and Mono-, di- and trialkanol, preferably ethanolamine salts.

Darin bedeuten:

R¹

unabhängig voneinander eine Alkylgruppe mit 1 bis 6 C-Atomen, eine Vinylgruppe oder eine Phenylgruppe, vorzugsweise eine Methylgruppe,

R²

aminogruppenhaltige Alkyl- oder Arylreste mit primäre, sekundären, tertiären oder quaternären Aminogruppen,

R³

eine Alkylgruppe mit 1 bis 6 C-Atomen,

R⁴

eine Alkylgruppe, Phenylgruppe oder Aminoalkylgruppe mit 1 bis 12 C-Atomen,

q, x und m = 0 bis 5,
m + n + p = 1 bis 10, vorzugsweise 2 bis 6,
y + z = 20 bis 1400, wobei Z auch O sein kann.The aminosiloxanes b) can be represented by the following general formula units:

Where:

R¹

independently of one another an alkyl group with 1 to 6 carbon atoms, a vinyl group or a phenyl group, preferably a methyl group,

R²

alkyl or aryl radicals containing amino groups with primary, secondary, tertiary or quaternary amino groups,

R³

an alkyl group with 1 to 6 carbon atoms,

R⁴

an alkyl group, phenyl group or aminoalkyl group with 1 to 12 C atoms,

q, x and m = 0 to 5,
m + n + p = 1 to 10, preferably 2 to 6,
y + z = 20 to 1400, where Z can also be O.

The aminosiloxanes can e.g. by reaction of γ-aminopropyl-trialkoxysilane with α, ω-hydroxy-terminated polydimethylsiloxanes or by equilibration with amino-functional siloxanes.

wobei R³ die obige Bedeutung und Y den obigen Wert hat und R Wasserstoff, einen Alkyl- oder Aminoalkylrest bedeutet,
eingesetzt.To be favoured

where R³ has the above meaning and Y has the above value and R represents hydrogen, an alkyl or aminoalkyl radical,
used.

The hydrocarbons are used in amounts of 25 to 65% by weight, based on the sum of components a) to d); preferably 37 to 52% by weight. The proportion of chlorinated hydrocarbons is 20 to 40, preferably 25 to 35% by weight. The emulsifier is preferably used in an amount of 2 to 15, preferably 5 to 10% by weight and the aminosiloxane in an amount of 5 to 20% 10 to 13 wt .-% added.

The hydrophobizing agent can be prepared anhydrous or as an aqueous emulsion with up to 68% water, preferably 24 to 48% by weight water.

Since the water-free preparations from components a) to c) can separate at temperatures below 10 ° C. and are expediently emulsified in water before use on leather, the preparation of emulsions which can be diluted with water is particularly recommended.

The following examples explain the preparation and use of the claimed aminosiloxane-containing preparations for waterproofing leather:

example 1

• 1.1 Preparation of the preparation for waterproofing leather:
  79 g of an aminosiloxane preparation obtained by reacting 74 g of α, ω-hydroxy-terminated polydimethylsiloxane with a viscosity of 500 mm² / sec with 5 g of N-β-aminoethyl-aminopropyltrimethoxysilane at 70 to 75 ° C. (stirring for 1 hour) are obtained with 310.6 g chlorine paraffin (C chain length 10 to 18 and 20% chlorine content), 153.3 g n-paraffin mixture (softening point 40 to 42 ° C and oil content approx. 2%, viscosity at 99 ° C 2.4 centistoke), 80 , 1 g of oleyl amide of methylaminoacetic acid and 32 g of triethanolamine in a closed stirred tank with reflux condenser and thermostat mixed by intensive stirring at 70 ° C. At this temperature, 345 g of deionized, 70 ° C. hot water are then stirred in and the mixture is homogenized for 60 minutes without further heat by intensive stirring.
• 1.2 Waterproofing heavy upper leather
  The following percentages refer to the fold weight of the chrome leather.
  In practice, chrome-tanned cowhide leather folded to 2.0 to 2.1 mm is washed, neutralized, optionally dyed and retanned, as described in detail in the following recipe, and then treated with 6.5% of a water-repellent water-repellent emulsion prepared according to Example 1.1 and then fixed with a 33% basic chromium III sulfate. After overnight storage in a moist state, vacuum and hanging drying as well as studs, ventilation and re-vacuuming, the leathers are extremely waterproof.
  Several test specimens of the leather, which were treated by this method with the hydrophobic emulsion prepared according to Example 1.1, showed in the test for dynamic water penetration (Maeser) with continuous, strong compression and bending stress in a water bath after 50,000 bending stresses (flexing) within after approx. 8 hours no water penetration with a water absorption of less than 12%.
  Leather produced under the same conditions with conventional hydrophobizing emulsion - without aminosiloxane - can withstand about 3000 to 5000 flexes in 1/2 to 1 hour until the first water penetration under the test conditions described above and with a subsequent silicone treatment are usually Depending on the amount of silicone applied, approximately 15,000 to 20,000 compression and bending stresses can be reached (in 3 to 4 hours).
  
  
  
  
  According to this procedure, 2 chromium-tanned halves of beef, which are customary in practice, were treated with the aminosiloxane-containing hydrophobicizing agent according to the invention. For this purpose, 2 chrome-tanned cowhides were split along the back line after folding. The left half of skin I and the right half of skin II were made hydrophobic together with the preparation containing aminosiloxane as described, and the corresponding halves were otherwise comparable Conditions treated with a conventional water repellent without aminosiloxane.

Example 2

• 2.1 Preparation of the aminosiloxane preparation:
  935 g of octamethylcyclotetrasiloxane, 27.5 g of γ-aminopropyltriethoxysilane and 37.5 g of a 10% strength solution of potassium hydroxide in ethanol are placed in a 1 liter three-necked flask equipped with a stirrer, thermometer and reflux condenser, and the mixture is stirred for 5 hours at 140 ° C. while removing the distillate. The mixture is then cooled below 80 ° C. and 4.4 g of acetic acid are added. The mixture is stirred for a further hour at 80 ° C. and then 3.7 g of anhydrous soda are added, the pressure is reduced to 30 to 40 mbar and distilled at this pressure to a bottom temperature of 140 ° C. The template is then changed, the pressure is reduced to 5 to 10 mbar and baked for 1 hour at 140 ° C. and 5 to 10 mbar. After cooling to below 30 ° C and pressure equalization with nitrogen, the mixture is filtered.
  The resulting, clear and slightly yellow aminosiloxane oil has the following characteristics:
  Viscosity: 344 m.Pas (Köppler 23 ° C)
  Solids content: 95.1% (according to DIN 53 182)
  Titration: 0.133 mmol NH₂ / g
  Density: 0.975 g / ml at 23 ° C
• 2.2 Preparation of the water repellent preparation:
  73.6 g of the aminosiloxane preparation thus obtained are mixed with 316.6 g of chlorinated paraffin (C chain length 10 to 18 and 20% chlorine content), 156.3 g of n-paraffin mixture (softening point 40 to 42 ° C, oil content approx. 2% and viscosity at 99 ° C (24 centistokes), 90.1 g of oleylamide of methylaminoacetic acid and 32 g of triethanolamine in a three-necked flask with a stirrer, thermometer and reflux condenser at 70 ° C.
  At this temperature, 655 g of deionized, 70 ° C. hot water are then stirred in and the resulting emulsion is homogenized for 60 minutes by intensive stirring without additional heat.
• 2.3 Hydrophobization of heavy shoe split suede
  In practice, chrome-tanned and 1.5 to 2.0 mm thick cattle leather slits are washed, neutralized, optionally dyed and retanned, as described in more detail in the recipe below, then with 8% of a water-dilutable 50% water repellent prepared according to Example 2.2 -Emulsion treated and then fixed with a 33% basic chromium III sulfate. After overnight storage in a moist state, vacuum and hanging drying as well as studs, ventilation and renewed vacuum drying, the leathers are very well waterproof and differ in the other leather properties not of split suede leathers that have been produced in practice without hydrophobic agents.
  In the Bally penetrometer at 10% compression, the leather, which had been hydrophobicized according to the process, did not show any water penetration after 8 hours and the water absorption was about 8%.
  The percentages in the following recipe refer to the fold weight of the chrome-tanned split leather.
  

Claims (1)

1. Hydrophobising agent for leather, containing the following constituents:

   a) saturated and unsaturated, straight chained and branched hydrocarbons having at least 10 carbon atoms which are partially halogenated

   b) aminosiloxanes or aminopolysiloxanes

   c) carboxyl group-containing emulsifiers which are fixed in the leather by acids or multivalent metal ions, and optionally

   d) water.