Classifications

• • C—CHEMISTRY; METALLURGY
  • C14—SKINS; HIDES; PELTS; LEATHER
  • C14C—CHEMICAL TREATMENT OF HIDES, SKINS OR LEATHER, e.g. TANNING, IMPREGNATING, FINISHING; APPARATUS THEREFOR; COMPOSITIONS FOR TANNING
  • C14C9/00—Impregnating leather for preserving, waterproofing, making resistant to heat or similar purposes
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/4935—Impregnated naturally solid product [e.g., leather, stone, etc.]

Definitions

• the present invention relates to and has as its objects an lmproved process for the filling of leather with certain dispersions of finely divided solid particles.
• the embedding of finely divided solid fillers into leather in the presence of dispersing agents is known. It is the purpose of the dispersing agents to conserve the finely divided form of the fillers and to ensure their even distri- In general, the dispersing agents themselves do not improve the plumpness of the leather and they rather detrimentally affect the water absorption of the leather.
• finely divided solid fillers may advantageously be embedded in the leather with dispersing agents which are Water-soluble products precipitable by acids and obtainable in known manner from dicyandiamide, formaldehyde and water-soluble dispersing salts of organic sulfonic acids, especially the sodium salt of dinaphthyl methane disulfonic acid; an acid, or a compound having an acid reaction in aqueous solution being added before, during or after the embedding of the fillers, and the leather having a pH value of less than 7, preferably of 3.5-5.5, at least at the end of the treatment.
• dispersing agents which are Water-soluble products precipitable by acids and obtainable in known manner from dicyandiamide, formaldehyde and water-soluble dispersing salts of organic sulfonic acids, especially the sodium salt of dinaphthyl methane disulfonic acid; an acid, or a compound having an acid reaction in aqueous solution being added before, during or after the embedding of the fill
• dicyandiamide, urea, melamine and the like, and formaldehyde may be condensed at a pH value of more than 7 in the presence, if desired, of water-soluble monoor polyhydric alcohols and/ or water-soluble mono or poly-saccharides and/or water-soluble salts of sulfurous acid and/ or other compounds condensable with oxo-compounds, such as urea or melamine, and there may be added before, during or after the condensation a water-soluble, dispersing salt of an organic sulfonic acid, especially the sodium salt of dinaphthyl methane disulfonic acid, and the condensation is allowed to proceed as long as the condensation products containing the aforesaid salt are still Water-soluble.
• the aforesaid acid-precipitable products contribute to the improvement of the leather plumping and, since they are easily convertible into a water-soluble state, they impair the water-absorption of the after-treated leather only to a lesser degree.
• the dispersing agents applicable according to the invention have an afiinity for the leather fibre and not only act as carriers for the fillers but also improve the fixation of the fillers in the leather as they are insolubilized during or after the embedding process. During the conversion of the compounds applicable as dispersing agents according to the invention into an insoluble form, the fillers are obviously covered by these compounds thus fixing them to the fibre.
• fillers there may be used, for example, finely divided silicic acid, calcium silicate, magnesium silicate, aluminiurn silicate and the like, aluminum oxide, meal aluminates such as calcium aluminate, magnesium aluminate and the like, titanium dioxide, carbon black, iron oxide pigments, metal titanates, naturally occuring silicates, aluminates and the like, such as china clay, kaolin, diatomaceous earth, kieselguhr, talc, gypsum, barium sulfate, zinc sulfide or mixtures thereof and the like.
• organic fillers may be used such as polyvinyl chloride or vinyl copolymerisate, butadiene styrene copolymerisates, finely divided cellulose, starch and derivatives thereof, especially ethers, insoluble urea formaldehyde condensates and the like.
• the proportion of the products applicable as dispersing agents with respect to the fillers may vary within a wide range, and depends largely upon the filler or the dispersing agent to be used.
• 100 parts of the mixture of the inventive dispersing agent and filler may contain from about 1 part to parts of filler.
• the inventive mixture contains between 10 to 50% of filler.
• the particle size of the filler usually should be at least less than 0.05 mm., but preferably between about 0.1 to 50a.
• the amount of the inventive mixture of dispersing and filling agent used in practice is from about 1 to 30% (of dry substance), but especially 3 to 10% referred to the Wet tanned leather (e.g.
• acids such as hydrochloric acid, sulfonic acid, boric acid, formic acid, acetic acid, propionic acid, lactic acid, organic sulfonic acids such as methane sulfonic acid, benzene sulfonic acid, dinaphthyl methane disulfonic acid and the like, or compounds having an acid reaction in an aqueous solution such as chromium, aluminium, zirconium or zirconyl salts of strong acids, is advantageously effected towards the end of the embedding process.
• the addition may be dispensed with, especially when the leather possesses at the end of the treatment a high acidity, i.e. a pH value of less than 7, preferably of 4.5-5.5
• Example 1 parts of a cow hide chrome tanned in conventional manner and shaved to a thickness of 1.8 millimeters are neutralized at 35 C. with 1 part of calcium formate and 0.8 parts of sodium bicarbonate in 300 parts of water so that the moist leather out has a pH value of 5.6.
• the leather is milled with a mixture of 3 parts (solids) of a resin obtainable according to Example 1 of US. patent specification No. 2,737,504, and 3 parts of calcium silicate having a particle size of 10 microns and parts of water at 60 C., for 45 minutes. After this period of time the liquor is to have a pH valve of 5.2.
• the dispersing agent and filler is then well absorbed by the leather.
• the leathers thus obtained have, compared with the pure a chrome tanned leather, an improved plumpness, good grain resistance and pleasant handle in addition to level dyeing, especially at the marginal parts of the hide.
• Example 2 The process is carried out as indicated in Example 1 using a resin obtainable in analogous manner, but adding to the reaction mixture another 120 parts of isopropyl alcohol before the condensation starts.
• the condensation time, as against that of Example 1, is prolonged to -6 hours until the water-insoluble state is attained.
• the leather thus obtained shows similarly improved properties to that obtained according to Example 1.
• Example 3 The process is carried out as indicated in Example 1 but instead of calcium silicate there is used a commercial finely dispersed silicic acid, having a particle size of 0.02- 0.1 micron. There is likewise obtained a leather with increased plumpness.
• Example 4 100 parts of shaved chrome-tanned calf skins are thoroughly rinsed with warm water at 50 C. and then milled at 60 C. for 1 hour with a mixture from 5.2 parts of the resin described below and 0.4 part of a commercial titanium dioxide pigment in 120 parts of water. After this time, the filling and dispersing agent is well absorbed by the leather. The pH value of the liquor should be 5.0-5.4. The leather is briefly rinsed and stuifed with a fat-liquoring agent fast to light.
• the leather thus obtained has a stronger grain and a lighter color.
• the dressing ability of the leather is very good.
• Example 5 The process is carried out as indicated in Example 4 but instead of titanium dioxide there are used 0.4 part of a finely divided kaolin and 7 parts of a resin obtained in the following manner: 84 parts of dicyandiamide, 28.5 parts of sodium meta-bi-sulfite, 325 parts of 37% formaldehyde and 135 parts of an approximately 50% idelimed and neutral sulfite waste liquor are heated under reflux for 4 hours.
• the leather obtained according to this process shows, when compared with pure chrome leather, improved properties similar to those produced according to Example 4.
• Example 6 100 parts of shaved bark-tanned sheepskin are briefly rinsed and then milled at 35 C. for 10 minutes with 80 parts of water and 1% of a medium sulfonated sperm oil. A mixture of 4 parts (calculated on dry substance) of a condensation product is then added, obtained as indicated in Example 1, 4 parts of a finely divided polyvinyl chloride and 2 parts of a neutral condensation prod uct from dihydroxy diphenyl sulfone, formaldehyde and naphthalene-sulfonic acid, obtainable for example according to the instruction given in Example 1 of German patent specification No. 611,671, and the leather is milled for 30 minutes.
• Process for the filling of leather which comprises milling leather with a finely divided filler in the presence of a water-soluble dispersing agent, precipitable by acid, obtainable by condensation of carbamide with formaldehyde in a nonacid medium and containing a water-soluble salt of an organic sulfonic acid, and in the presence of sufiicient acid to precipitate the dispersing agent.
• Process for the filling of leather which comprises milling leather with a finely divided filler in the presence of a water-soluble dispersing agent, precipitable by acid, obtainable by condensation of dicyandiamide with formaldehyde in a nonacid medium and containing a watersoluble salt of an organic sulfonic acid, and in the presence of sutficient acid to precipitate the dispersing agent.
• Process for the filling of leather which comprises milling leather with a finely divided filler in the presence of a water-soluble dispersing agent, precipitable by acid, obtainable by condensation of dicyandiamide and urea with formaldehyde in a nonacid medium and containing a water-soluble salt of an organic sulfonic acid, and in the presence of sufficient acid to precipitate the dispersing agent.
• Process for the filling of leather which comprises milling leather with a finely divided filler in the presence of water-soluble dispersing agent, precipitable by acid, obtainable by condensation of dicyandiamide and melamine With formaldehyde in a nonacid medium and con taining a water-soluble salt of an organic sulfonic acid, and in the presence of sutficient acid to precipitate the dispersing agent.
• Process for the filling of leather which comprises milling leather with a finely divided filler in the presence of a Water-soluble dispersing agent, precipitable by acid, obtainable by condensation of dicyandiamide melamine and urea with formaldehyde in a nonacid medium and containing a water-soluble salt of an organic sulfonic acid, and in the presence of sufiicient acid to precipitate the dispersing agent.
• Process for the filling of leather which comprises milling leather with a finely divided filler in the presence of a water-soluble dispersing agent, precipitable by acid, obtainable by condensation of dicyandiamide with formaldehyde in a nonacid medium and containing a Watersoluble salt of an organic sulfonic acid, and finishing the milling process by adjusting the medium to a pH value from 3.5 to 5.5.
• a process for the filling of leather which comprises milling leather with an alkaline dispersion comprising a finely-divided filler and a water-soluble dispersing agent precipitable by acid obtainable by condensation of a carbamide with formaldehyde in a nonacid medium and containing a water-soluble salt of an organic sulfonic acid and finishing the milling process by adjusting the dispersion to a pH of less than 7.
• a process for the filling of leather which comprises milling leather having a pH of less than 7 with a dispersion of a finely-divided filler and a water-soluble dispersing agent precipitable by acid obtainable by condensation of a carbamide with formaldehyde in a nonacid medium and containing a water-soluble salt of an organic sulfonic acid, said leather containing sufi'rcient acid to precipitate the dispersing agent in situ.
• a process for the filling of leather which comprises milling leather with a finely-divided filler in the presence of a water-soluble dispersing agent precipitable by acid obtainable by condensation of dicyandiamide and urea with formaldehyde in a nonacid medium and containing a water-soluble salt of an organic sulfonic acid and in the presence of sufficient acid to precipitate the dispersing agent.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Treatment And Processing Of Natural Fur Or Leather (AREA)

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Citations (9)

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  • CA CA618725A patent/CA618725A/en not_active Expired
  • IT IT590719D patent/IT590719A/it unknown
• 1957
  • 1957-05-17 DE DEF23051A patent/DE1263978B/de active Pending
• 1958
  • 1958-04-29 CH CH5890758A patent/CH372420A/de unknown
  • 1958-05-07 GB GB1467158A patent/GB832664A/en not_active Expired
  • 1958-05-12 US US73441158 patent/US3053697A/en not_active Expired - Lifetime
  • 1958-05-14 FR FR1209128D patent/FR1209128A/fr not_active Expired

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