FR2481319A1 - NEW SOLID COMPOSITIONS FOR SKIN TANNING - Google Patents

Abstract

THE OBJECT OF THE INVENTION IS A SOLID COMPOSITION COMPRISING: A. A FERROUS SALT; B. AN ALIPHATIC HYDROXY-CARBOXYLIC ACID POSSIBLY IN THE FORM OF A SALT, AND ITS USE AS A TANNING AGENT.

Description

The present invention relates to composi-

  solid tanning processes and a tanning process

  skins in the presence of such a composition.

  It is generally accepted that although ferric salts may be used as

  tanning, ferrous salts are not well known for this purpose.

  Nevertheless, French Pat. No. 881,676 describes a tanning process in which a solution containing

  a ferrous salt and tartaric or citric acid.

  However, according to the single example, the pseudo-tanned skin is oxidized in the air. In a thesis written in 1947, he is

  specified that ferrous salts are inactive for the tan-

  swimming skins. The only known tanning process using iron salts is the "ferrigan" tanning process,

at stake are ferric salts (Fe III).

  The applicant has now found that it is possible to use solid mixtures of a ferrous salt (FeII) and an aliphatic hydroxycarboxylic acid for tanning skins without an oxidation step, that is to say that the ferrous salt acts in divalent form

as a tanning agent.

  The invention thus comprises a tanning composition in solid form comprising a) a ferrous salt (FeI), and b) an aliphatic hydroxy-carboxylic acid, optionally

in the form of a salt.

  The preferred ferrous salt a) is sulphate

  ferrous in the form of heptahydrate (FeSO4,7H20).

  Suitable aliphatic hydroxycarboxylic acids as component b) are those containing from 2 to 8 carbon atoms, one or more carboxy groups, preferably from 1 to 3 carboxy groups, and one or more

  hydroxy groups, preferably from 1 to 6 hydroxy groups.

  Preferred aliphatic hydroxycarboxylic acids include glycolic acid, lactic acid, tartaric acid, malic acid, citric acid and acid.

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  gluconic acid or mixtures of these acids. Suitable salts for acids b) are for example salts

  alkali metals, for example sodium or potassium

  sium. Preferably, component b) is present in the form of a free acid, except for gluconic acid which is preferably used in the form of an alkali metal or alkaline earth metal salt. for example sodium or calcium salt. It is also possible to use gluconic acid in dehydrated form, for example gluconolactone-1 (3). Component b)

preferred is tartaric acid.

  The weight ratio of ferrous salt (a) to

  b) is between about 3: 1 and 5: 1; he is

preferably of the order of 4: 1.

  The solid compositions of the invention are prepared by mixing and grinding the two components according to the usual methods, until obtaining

a homogeneous powder.

  The invention also comprises a process for tanning skins ,. characterized in that the skins are contacted with a solid tanning composition

as described above.

  The amount of the composition to be used varies within wide limits, depending on the origin and nature of the skins and the type of leather desired. Satisfactory results are obtained when the composition is used in an amount of between 7 and 40%, preferably

  between 13 and 25% of the weight of the pickled skin.

  When, for example, a composition containing ferrous sulphate heptahydrate and tartaric acid is used, the amount of composition to be used is

  preferably the following, for each type of skin cited.

  Amount of Composition FeSO4, 7H20% in% Sheep and lamb skins 15.2 12 Goat and kid skins 15.2 12 Pork skins 20.3 16 Skins of veal and cowhides 20.3 16 The tanning can be carried out according to known methods, for example as for tanning with chromium powder. The degree of penetration

  ferrous salt depends on factors such as

  treatment bath temperature, bath temperature, barrel rotation speed and -thickness

  skins. In general, the duration of the

  with the compositions of the invention is between 1 and 4 hours. The pH of the treatment bath is then adjusted to about 4.2-4.8. After tanning, the leather is usually left to ripen for 2 to 3 hours

  days and, if desired, can then be dyed.

  The affinity of leathers for dyes, when the leathers have been tanned with the new compositions, is good. In addition, the resulting leather is flexible and flexible, and has a full hand. The leather thus obtained, subjected for one minute to water at 900 does not shrink. It is also possible to use the compositions of the invention for tanning skin in combination

  with chrome tanning compositions.

  The invention also includes leathers

  obtained according to the tanning process specified above.

  The following examples illustrate the present invention without in any way limiting its scope. Parts are by weight and all temperatures are in degrees Celsius. All percentages are by weight and unless otherwise stated

  contrary, relate to the pickled weight.

Example 1

  30 to 3 skins of pickled and defatted sheep weighing 2300 g were added to a glass slice 60 cm in diameter and rotating at 10 rpm, 100% of a 5% solution of sodium chloride. sodium then 1% of an amphoteric fatty acid derivative containing sulfo groups (commercial product, for example Tergolix A, Sandoz SA, Switzerland). After 10 minutes, 0.8% of 85% formic acid is added. and 0.1% concentrated sulfuric acid. We still let spin for

minutes. The final pH is 1.7.

  15% of a homogeneous mixture in powder, containing 790 parts of FeSO4,7H20 and 210 parts of tartaric acid are then added. After 2 hours of treatment, the final pH is 1.8. We add slowly,

  drip, and in the space of 2 hours, 5.5% of

  calcined sodium bonate (diluted in water to 1:20), the final pH being 4.9. After letting the barrel run for another hour, the bath is allowed to sit overnight and in the morning, it is restarted for another hour. The pH is 3.8. 15% calcined sodium carbonate (diluted in 1:20 water) is slowly added dropwise over 15 minutes and allowed to run for a further

  one o'clock. The final pH is now 4.2.

  The skins are allowed to ripen for 3 days; in the wet state, these skins have a light yellow-green color. When they are tested

  hot water at 90 for a minute they do not shrink

  do not shout. After spinning the leathers, they are

subject to the shaving.

  The following percentages data are

  now report to the weight being cleared.

  The tanned skins are washed with 500% water for 10 minutes and then allowed to rotate for minutes with 300% of water at 30 and 1% of sodium formate, the final pH of the bath being 4.9%. leathers with bromcresol green gives a blue green color. To dye, 300% of water containing 40.2% of a commercial anionic fatty acid derivative (for example Sandolix WWL, Sandoz SA, Switzerland) and 3% of the CI Acid Brown 362 dye are added to the leathers. dyed for 45 minutes. After addition of 1% of 85% formic acid, dye for another 15 minutes. The leathers are then washed for 15 minutes with 500% water and fed with 300% water containing 50.4% of a commercial sulphated fish oil and 4% of an emulsion of a derivative. synthetic anionic fatty acid (commercially available, eg Sandolix SE, Sandoz SA, Switzerland). After 60 minutes, it is acidified with 1% of 85% formic acid. It is then washed with 500% of water at 30 for 5 minutes and, after maturing on the bridge, the leather is wrung out and stretched.

  (to get a finer flower) and dry it.

  After drying, the leathers are laid in sawdust

  wet, they are hoisted and stretched.

  Soft leathers are obtained, dyed with a good

  unison and with good penetration of the dye.

Example 2

  A 3200 g weight of pickled bovine skin was treated for 10 minutes in a 60 cm diameter glass barrel rotating at 8 rpm with 100% 5% sodium chloride solution. then, after addition of 0.2% of sulfuric acid,

  it is treated for another 40 minutes (final pH = 1.6).

  20% of a powder mixture of 790 parts of FeSO 4 · 7H 2 O and 210 parts of tartaric acid are added and the mixture is treated for 4 hours (final pH 1.7). Then it is added slowly, dropwise and in the course of 5 hours. portions, at 30 minute intervals, 5.0% sodium carbonate (diluted in 1:20 water) and treated for one hour (final pH = 4.2). After letting the skin rest for a night in the bath, it is treated

  tomorrow morning for another 30 minutes (final pH = 3.9).

  1.5% of sodium carbonate (diluted in 1:20 water) is slowly added dropwise over one hour and treated for a period of one hour.

1 hour (final pH = 4.8).

  After maturing for 3 days, the resulting leather has a light yellow green color and does not shrink when subjected to the hot water test at 900 for one minute. Then the leather is wrung out and it is stripped. The leather is washed for 10 minutes at 30 with 500% water and then treated with 300% water at 300 and 0.8% formate.

  of sodium for 30 minutes (final bath pH = 4.8).

  A slice of leather with bromo-cresol green is

  blue green on the outside and yellow on the inside.

  After washing the leather for 10 minutes at 300 with 500% water, it is dyed for 30 minutes at 400 with 300% water, 2% of the anionic fatty acid derivative of Example 1 and 1%. Acid Brown 362 CI dye. The bath is then slightly acidified by addition within 15 minutes of 0.5% of 85% formic acid and then fed for 45 minutes at 40 with 300% water, 4% of fish oil

  and 4% of the anionic fatty acid derivative of Example 1.

  After acidifying for 10 minutes with 0.5% formic acid, the leather is washed for 5 minutes with 500% water, dried, placed in

  sawdust, it is palised and then stretched.

  You get a full leather with a touch

somewhat firm.

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Example 3

  In a glass barrel 60 cm in diameter, rotating at 10 revolutions / minute, 2 skins of

  pickled and defatted sheep, weighing 1500 g.

  100% of a 5% chlorine solution is then added.

  sodium chloride and the skins are treated for 10 minutes.

  After addition of 20% of a mixture, in powder form, of 819 parts of FeSO 4, 7H 2 O, 74 parts of tartaric acid and 107 parts of sodium gluconate,

  it is treated for 2 hours, the final pH being 2.0.

  Then add in 5 portions, at intervals of 30

  minutes, 6% sodium carbonate diluted 1:20.

  After 2 hours, the final pH is 4.5; the tanned skins are allowed to ripen on the easel. When submitted one hour after tanning with hot water test

  for 90 minutes, they do not shrink.

Example 4

  Two cowhide skins of 7200 g are dehaired, as for a chrome tanning then confit and pickled. Tanning is started with 3% commercial chrome tannin (26% chromium oxide and 33% basicity). After 2 hours, 8% of a mixture of 790 parts FeSO47H20 and 210 parts is added.

  tartaric acid. 2 hours later, add slowly

  drop by drop and in 2 hours 3% of sodium carbonate diluted 1:20. It is then treated for a further two hours and the final pH is then 4.6. The calfskin is allowed to ripen on the easel. One hour after tanning with hot water, for a minute at 90 Q these leathers

do not shrink.

Example 5

  Two skins of 620 g Australian lamb are dipped, washed and pickled according to the usual methods. After pickling, the skins are left to rest for a day, then tanning. The skins are introduced into a bath composed of 2000% of 35% water, 50 g / l of sodium chloride and 0.5 g / l of the amphoteric fatty acid derivative containing sulfo groups of Example 1. After 20 minutes, 16 g / l of a mixture of 790 parts is added to the bath.

  anhydrous FeSO 4 · 7H 2 O and 210 parts of tartaric acid.

  2 hours later, 4 g / l of an emulsion is added to the bath.

  aqueous solution of a cationic polyglycol aliphatic amide ester (commercial product, for example Katalix GS Sandoz S.A., Switzerland). After another 2 hours, neutralized by addition of 5 portions of 5.0 g / l of sodium bicarbonate. This addition is slow, at intervals of 30 minutes. The skins are further treated for one hour and then allowed to ripen for 1 day. When subjected to the water test

  hot at 80 during the minute, they do not shrink.

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Claims (13)

  1. A novel solid composition characterized in that it comprises a) a ferrous salt (Fe i), and b) a possible aliphatic hydroxy-carboxylic acid; in the form of a salt.   2. A composition according to claim 1, characterized in that it contains, as ferrous salt, ferrous sulfate heptahydrate.   3.- A composition according to any one   claims 1 and 2, characterized in that the   component b) is an aliphatic hydroxy carboxylic acid   than containing from 2 to 8 carbon atoms, from 1 to 3   carboxy groups and from 1 to 6 hydroxy groups.   4. A composition according to claim 3, characterized in that the aliphatic hydroxycarboxylic acid is chosen from glycolic acid,   lactic acid, tartaric acid, malic acid,   citric acid and gluconic acid or mixtures thereof.   5. A composition according to claim 4, characterized in that glycolic, lactic, tartaric, malic and citric acid are used under form of free acids.   6. A composition according to claim 4, characterized in that gluconic acid is present in the form of a salt.   7. A composition according to claim 6, characterized in that gluconic acid is present   in the form of a salt of sodium or calcium.   8.- A composition according to any one   Claims 1 to 5, characterized in that   contains a) ferrous sulphate heptahydrate, and b) tartaric acid.   9.- A composition according to any one   Claims 1 to 8, characterized in that the 2 4'8! 32 1 9   ratio of ferrous salt a) to component b) is understood between 3: 1 and 5: 1.   10.- The application of solid compositions   as specified in any one of the claims   1 to 9 as tanning agents.   11. A process for tanning the skins, characterized   in that the skins are contacted with a solid composition as specified in any one of Claims 1 to 9.   12. A process according to claim 11, characterized   characterized in that from 7 to 40% by weight of solid composition is used relative to the weight of the pickled skin. 13.- Leather, characterized in that it has been treated according to the process specified in   any of claims 11 and 12.