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
  • C14C13/00—Manufacture of special kinds or leather, e.g. vellum

Definitions

• This invention relates to an improved process for the treatment of skins with attached wool or hair.
• the present invention is useful generally in any treatment of skins with wool or hair attached, it is described hereinafter specifically in relation to the tanning of such skins, and the tanning and dyeing of such skins.
• felting will be used to cover all types of disarrangement of wool or hair fibres such that fibres are no longer discrete entities which can move independently of other fibres.
• the term covers all types of entanglement, matting, knotting, twisting, curling, balling and any other arrangements of fibres which prevent the independent movement of a fibre at any place between its root and tip.
• Skins to be treated with wool or hair attached vary widely in size and quality.
• the type, colour, and quality of the wool or hair is also highly variable.
• the wool or hair can be anywhere up to 15cm in length with 2-5cms being the most commonly encountered.
• the diameter of the fibre also varies considerably but is generally greater than 25 microns. Smaller diameter wools and hairs have a great tendency to felt.
• the conventional procedure presently used for the production of tanned skins with wool or hair attached requires prolonged exposure of the skin to aqueous solutions with mild agitation.
• the float ratio (being the ratio of the weight of the solution in kg or, approximately, the volume of the solution in litres, to the dry weight of the skin in kg) is normally maintained at a high level (8:1 - 14:1) in conventional processes to reduce the propensity of the wool or hair to felt.
• the method and type of agitation depends on the equipment used but those familiar with the art will be aware that agitation is kept to a minimum to avoid or decrease felting.
• a method of tanning an animal skin with wool or hair attached thereto in which the animal skin is pickled in an acidic solution and thereafter tanned in a solution containing at least one tanning agent characterised in that a holding agent comprising an oil, wax or grease is present on the wool or hair of the animal skin to hold the wool or hair together whilst the animal skin is pickled and tanned and the animal skin is thereafter scoured so to remove the holding agent.
• the holding agent may be made industrially and applied to the wool or hair prior to the treatment steps.
• the holding agent is present as the natural oils, waxes and greases which are already present on the hair or wool prior to the normal cleansing and scouring step and there is therefore normally in the case of uncleansed skins no need to specifically add a holding agent.
• the skins are fleshed in accordance with known procedures. If found necessary the fresh (green) or preserved (salted, dried or short term preserved by any method) skins are prior to the fleshing step subjected to a soaking process preferably in the absence of surface active agents to remove loosely attached dirt, dung and blood and to rehydrate preserved skins. Soaking times depend on the nature of the skin but preferably range from 1 to 40 hours with or without the presence of preservatives and with or without agitation.
• the skins After the skins have been fleshed they are not further cleansed but are immediately subjected to a pickle treatment.
• the skins are treated with an acid solution preferably containing an electrolyte.
• a suitable electrolyte is sodium chloride.
• the pickling treatment is conducted in a paddle or drum or hide processor although any suitable container may be utilized. Many vessel types are known in the art and any such equipment can be used for the process of the present invention.
• the acid used may be organic or inorganic or a combination of organic and inorganic acids.
• Other chemicals as are known in the art, can be added to the solution to impart special properties to the finished skin. These chemicals can be organic molecules or inorganic molecules which have a tanning action on the skin.
• the pickling treatment is preferably conducted with either continuous or intermittent agitation for periods up to 16 hours.
• the volume of the float may vary between 5 to 60 litres per skin and is most preferably in the range between 20 to 30 litres per skin.
• the pickled stock is then subjected to a tanning procedure preferably using a reduced float which may be for example 5 to 25 litres per skin. Most preferably the float is 12-15 litres per skin thus allowing a corresponding increase in the concentration of tanning agents and auxilliaries.
• the tanning procedure varies widely in its execution and the materials employed.
• Known tanning agents and auxilliaries may be used in the tanning step of the present invention utilizing chemicals known in the art to provide both thermal and biological stability to the skins and to bestow on the subsequent leather the desired properties.
• the equipment utilized in the tanning step can be any equipment known in the art including paddles or drums or hide processors so designed to give adequate agitation of the skins.
• Tanning can be undertaken on equipment that provides vigorous agitation of the skins. Vigorous agitation is preferably performed for any period up to 12 hours and most preferably for 6 hours.
• this period is substantially less than the period of treatment required in previous tanning steps.
• the skins After the skins have been tanned they are then scoured.
• the skins can be scoured by dry-cleaning methods using, for instance, hydrocarbon solvents or chlorocarbon solvents.
• the skins can be scoured in water.
• this step the residual greases and waxes are easily and rapidly removed to produce clean, tanned (and if desired) dyed skins.
• this step is preferably performed in a paddle, drum or hide processor.
• a float of 10 to 60 litres per skin is preferably used and most preferably ranges between 25 and 30 litres per skin.
• a surface active agent can be added to the water and if so added is preferably added in the range of 1 to 12 grams/litre. Most preferably the surface active agent is added in the range of 3 to 4 grams/litre.
• a hydrocarbon solvent may be added to the surface active agent. When used the hydrocarbon solvent is added preferably in amounts up to 20ml per litre with 5-10ml per litre being most preferred.
• the surface active agent may consist of in alkyl phenol derivative of an ethylene oxide condensate with 4-16 carbon atoms in the alkyl radical and 2 to 15 ethylene oxide units in the ethylene oxide moiety with 9 carbon atoms being the most preferred number of carbon atoms in the alkyl radical and 9 ethylene oxide units being the most preferred number of such units in the ethylene oxide moiety.
• a polyalkylene oxide condensate derivative of a fatty alcohol can be used with the alcohol, chain containing 4 to 16 carbon atoms and the alkylene oxide chain containing 5 to 15 alkylene oxide units. Mixtures of different surface active agents of the above types may be used.
• the temperature of the solution is preferably any temperature up to 70°C and is most preferably in the range of 58°C - 60°C.
• an amine ethoxylate detergent may be used.
• Use of thin agent has the additional advantage of allowing the scouring or cleansing step to be conducted at lower temperatures.
• the temperature of the scouring solution can be as low as 40°C. Most preferably it is 50°C.
• the scouring process is conducted for up to 30 minutes and is preferably in the range 10 to 20 minutes.
• the skins are then drained and rinsed with one or two changes of water.
• Each rinse is preferably equivalent to 10-25 litres of water per skin.
• the skins are treated in accordance with the scouring process described above.
• the scouring process can be effected by adding the scouring agents directly to the spent dye solution. In such instance the stock is then drained and if required can be subjected to a further similar cleansing process.
• the dyed skins may be subjected to a re-tanning procedure this may also be done prior to the scouring step.
• the re-tannage may be performed by the use of appropriate mineral or organic tanning agents (syntans) such as are well known to those practiced in the art. Following the completion of the tannage the skins are treated in accordance with the scouring process already described.
• Both packs were combined and subjected to a normal industrial pickle procedure in a hide processor using acetic acid, sodium chloride and aluminium sulphate as components of the pickle.
• the float was 14 litres per skin.
• the hide processor was rotated at 9 rpm for 2 minutes every 30 minutes for 16 hours.
• Both packs were combined for the pickling step which was conducted as for a normal industrial process in a hide processor.
• the components of the pickle solution were sodium chloride, aluminium sulphate and formic acid.
• the float was 14 litres per skin.
• the hide processor was rotated continuously at 2.5 rpm for 25 minutes and then for 2 minutes every 30 minutes for 17 hours.
• the skins were drained and rinsed following normal practice.
• Neosyn RW (6 kg) (Hodgson Tanning products) was premixed in water and added to the float in two aliquots during 25 minutes. After 55 minutes, the woolskins were scoured for 20 minutes in the same float using an alkyl phenol ethoxylate mixture (4g/litre). After draining the skins were refloated and rescoured for 18 minutes using the same detergent composition. The skins, after rinsing and draining were thoroughly clean and exhibited level dyeing.
• Paralene AMA (Yorkshire Chemicals) was added and the skins paddled continuously for 30 minutes and then intermittently for 15 hours at 3 minutes per hour.
• the pickle was dropped and the skins tanned in the following solution: 4,500 litres of water containing sodium chloride to 4 Bé (approximately 40g/litre), 1 kg of ethylene diamine tetra-acetic acid, 40 kg of aluminium sulphate, 25 kg of Neosyn HL (Hodgson Tanning Products) and 60 kg of chromium sulphate (26% Cr2O3; 33 1/3% basic; SO2 reduced).
• the skins were paddled for 30 minutes, then at 3 minutes per hour for 16 hours.
• the temperature was increased to 35°C and the pH raised to 3.8 using sodium bicarbonate.
• the skins were drained and refloated in 4,500 litres of water at 60°C.
• the skins were paddled for 30 minutes and then 250ml of 85% formic acid diluted with water was added slowly to the float and paddling continued for a further 30 minutes. 4 litres of sufactant mixture was added to the float and the skins scoured during 15 minutes. The skins were drained and refloated at 60°C and scoured again in an identical manner. The skins were drained and rinsed for 10 minutes at 50°C. Examination of the skins revealed the wool pile to be clean and evenly dyed.
• the present invention discloses a new process for the production of treated skins with attached wool or hair, making it possible to obtain a significant reduction in felting of wool or hair during tanning, or during tanning and dyeing, and a significant reduction in processing time - especially that pertaining to the tanning of the skin and a significant reduction in the time required to cleanse or scour the skins.
• the process provides for a significant reduction in the staining of the wool by chromium salts where these are used in the tanning step.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Treatment And Processing Of Natural Fur Or Leather (AREA)
• Treatments For Attaching Organic Compounds To Fibrous Goods (AREA)
• Meat, Egg Or Seafood Products (AREA)
• Chemical Or Physical Treatment Of Fibers (AREA)
• Medicines Containing Plant Substances (AREA)
• Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)

Applications Claiming Priority (3)

Publications (3)

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• 1987
  • 1987-04-20 YU YU00715/87A patent/YU71587A/xx unknown
  • 1987-04-27 NZ NZ220109A patent/NZ220109A/xx unknown
  • 1987-04-28 AT AT87902348T patent/ATE110791T1/de active
  • 1987-04-28 AU AU73090/87A patent/AU604017B2/en not_active Ceased
  • 1987-04-28 EP EP87902348A patent/EP0264398B1/en not_active Expired - Lifetime
  • 1987-04-28 DE DE3750457T patent/DE3750457D1/de not_active Expired - Lifetime
  • 1987-04-28 WO PCT/AU1987/000117 patent/WO1987006622A1/en active IP Right Grant
  • 1987-04-28 HU HU872942A patent/HUT47646A/hu unknown
  • 1987-04-28 JP JP62502819A patent/JP2667848B2/ja not_active Expired - Lifetime

Non-Patent Citations (6)

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