IE902735A1 - Process for the treatment of hides, and hides obtained - Google Patents

Abstract

Method for the antifungal and/or antibacterial treatment of hides. This method consists in treating these hides with a bath containing a lanthanum or cerium salt, for example a lanthanum acrylate.

Description

PROCESS FOR THE TREATMENT OF HIDES.

AND HIDES OBTAINED The present invention relates to a process for the treatment of hides and to the hides thus treated.

It relates more especially to a treatment which makes it possible to provide for better preservation of the latter from a biological standpoint, in particular during the process of preparation of the hides before or after their tanning.

At present, hides are generally marketed in various forms ί - in the crude state (saline-cured, brine-cured, saline-cured - dry and fresh, and the like) - in the pickled state (treatment with a solution 15 of strong acid in the presence of salt) - in the reversible pretanned state (BSH or BSS, wet white, dry white, for example) - in the tanned state (for example by treatment with chrome) - in the semi-finished state (referred to as stain) - or in the finished state.

These hides are often transported or stored in premises unsuited to their preservation; in particular, the humidity and hygiene conditions are conducive to the development of a bacterial and/or fungal contamination of the hides. The various treatment solutions used in each step of the preparation of a hide can possess an antibacterial or antifungal action. However, the latter is not sufficient to provide for adequate protection.

For this purpose, the proposal has already been 5 made to use products or compositions comprising compounds having an antifungal or antibacterial action, such as, for example, tri- or pentachlorophenols, para-/meta-cresol, ortho-phenylphenol and their sodium salts, benzothiazole derivatives (for example TCMTB), isothiazolones and metal salts such as zinc or copper salts .

These specific products have drawbacks, since they are generally difficult to remove. Thus, if the hides are treated with such products before or during the river operations, they will be present in the wastes recovered during the preparation of the hide, for example the fleshing. These polluted wastes cannot be recovered, in particular in the manufacture of collagen.

Moreover, these specific products are to be found in the waste waters of hide treatment, causing a pollution which is unacceptable to the environment. These products can also have a toxic effect for the processes of waste water treatment (biological treatment) employed in water purification stations.

In addition, these products can also be troublesome in the preparation of the hides after tanning, for example.

»E 902735 The object of the invention is, in particular, to remedy these drawbacks by proposing a process for the treatment of hides to preserve them from fungal or bacterial attack, capable of being applied at all stages or steps of the process of preparation of a hide.

To this end, the invention proposes a process for the treatment of hides to preserve them from fungal and/or bacterial attack, consisting in treating the hides with a treatment bath comprising at least one lanthanum or cerium salt.

Lanthanum or cerium salts are understood to mean any water-soluble salt such as the inorganic salts like the nitrates, chlorides or sulphates, for example, the organic salts or the organosulphonic salts or gluconates.

According to a preferred feature of the invention, the lanthanum or cerium salts are organic salts derived from a vinylcarboxylic acid such as, for example, acrylic acid or methacrylic acid.

Preferred salts of the invention are lanthanum acrylates and methacrylates.

The hides are treated with an amount of lanthanum or cerium, expressed as oxide, of between 0.02 % and 1.25 %, and preferably between 0.04 % and 1.25 %.

These percentages represent the mass of compound, for example of lanthanum (expressed as oxide), added to treat 100 kg of pelt. Pelt is understood to mean a hide stripped of hair and freed from fat and epidermis.

The percentages given in the text below always express the amount of product added to treat 100 kg of pelt, except where otherwise stated.

Advantageously, when the salt is a vinylcarboxylic acid salt, free vinylcarboxylic acid is added to the treatment solution.

According to another feature of the invention, the amount of vinylcarboxylate anion or of vinylcarboxylic acid expressed as free vinylcarboxylic acid is advantageously between 0.5 % and 5 % of pelt, and preferably between 1 % and 3 %.

This treatment bath may be used alone or in combination with a hide treatment bath such as, for example, pickling, tanning or pretanning baths like the BSH or BSS baths described, for example, in French Patent No. 2,610,643 of the Centre Technique Cuir Chaussure et Maroquinerie [Shoe and Fine Leather Technical Centre].

This antifungal and antibacterial treatment bath is suitable, in particular, for treating tanned hides in order to preserve them against moulds which impair their appearance.

Thus, the treatment bath according to the invention preserves the hides against attack by fungi such as, for example, Aspergillus niger. Penicillium funiculosum, Rhizopus nigricans and Trichoderma viride, or the bacteria Bacillus subtilis and Escherichia coli.

Another advantage of the process of the invention lies in the fact that the treatment agent does not bind irreversibly to the fibre of the hide, and can hence be readily removed by washing.

Thus, the subsequent treatments of the hide will not be impaired.

In addition, lanthanum or cerium are not harmful and can hence be discharged into the waste waters.

Moreover, the residual vinyl (acrylic or 10 methacrylic) monomers are readily polymerizable, this polymerization inhibiting the troublesome effect of these monomers.

The process for the invention may be carried out by any known means, and for example by impregnation with a treatment bath by passage through a drum.

The subject of the invention is also the hides treated according to the process of the invention and comprising lanthanum and/or cerium.

According to another feature, the treated hides 20 comprise from 0.02 % to 1.2 % of lanthanum or cerium, expressed relative to the weight of dry matter, that is to say after a drying in a ventilated oven for 6 hours at 105eC and a dehydration at this temperature to constant weight.

The treated hides also comprise vinyl units, either in monomer form or in polymerized form.

Other details, advantages and objective of the present invention will become more clearly apparent in the light of the examples given below exclusively as a guide.

A first series of experiments was carried out on a completely bated cattlehide.

This hide was cut into slices weighing 2000 grams.

Each slice was treated with an acid pickling solution whose composition will be given below: - Sample 1, control experiment: Pickling bath: 100 % of water; 10 % of NaCl; 1.5 % of sulphuric acid; pH 2.8.

The treatment lasted 3 hours.

These percentages express the mass of compound added per 100 kg of pelt.

The same applies to the following examples.

- Sample 2 Pickling bath: 100 % of water; 10 % of NaCl; 1.5 % of sulphuric acid; 1.96 % of lanthanum nitrate (0.725 % in terms of La2O3); pH 4.0.

The treatment lasted 3 hours.

- Sample 3 A solution of lanthanum acrylate and acrylic acid containing 172.8 g/1 of La2O3 and 476.3 g/1 of acrylic acid is added to a pickling bath containing 100 % of water and 10 % of salt to obtain a concentration of acrylic acid equal to 2 % and of La2O3 equal to 0.725 %.

The skin is treated for 3 hours at pH 5.8.

These samples are stored in an enclosure at 18-20°C with a relative humidity of 85 %.

Under these storage conditions, spots of mould are seen on control sample 1 after 18 days of storage, while samples 2 and 3 show no change.

- A second series of experiments was carried out on a cattlehide pickled with a pickling bath comprising 100 % of water, 5 % of NaCl and 1.5 % of sulphuric acid.

The skin was divided into strips, which were then 10 treated with stabilization baths to obtain BSH hides.

This stabilization treatment consists in adding to the pickling solution after neutralization 2 % (pelt weight) of aluminium polychlorosulphate (equivalent to 0.16 % expressed as A12O3), in the form of an aqueous solution possessing a basicity of 55 %, a degree of desulphating of 82 % and an Al2O3 content of 8.3 %, obtained according to the process described in European Patent Application No. 218,487.

During this treatment, an antifungal and/or antiseptic treatment agent was added to the stabilization bath, with neutralization of the bath to obtain a pH equal to approximately 4.

- Strip No. 1 Without antifungal and/or antiseptic treatment agent.

- Strip No. 2 A solution containing lanthanum acrylate and acrylic acid (172.8 g expressed as La203 and 476.3 g of acrylic acid), so as to have 0.4 %, expressed as La2O3, relative to the pelt weight (hide weight).

- Strip No. 3 23.8 g of lanthanum acrylate are added to the 5 stabilization bath to have a content of 0.04 %, expressed as La2O3, relative to the pelt weight.

- Strip No. 4 A conventional antiseptic agent marketed under the trade name Busan 30 is added to the stabilization bath to have a concentration of 0.07 % relative to the pelt weight.

These various strips are stored in a damp chamber at a temperature of 18-20°C with 85 % humidity.

Thus, after 11 weeks of storage, only the control strip No. 1 is invaded by moulds, at the level both of the full-thickness leather and of the grain split.

Furthermore, a portion of these strips was subjected to a chrome tanning or a vegetable tanning treatment.

These tanning experiments showed that treatment of the hides with a bath according to the invention has no influence on the tanning conditions and the properties of the tanned hides obtained.

A lanthanum assay on the BSH hides showed that the lanthanum content relative to the dry matter is 0.07 % for strip 3 and 0.46 % for strip 2.

Experiments on contamination of hides by moulds were carried out in Petri dishes, on small samples of leather inoculated with microbial cells on the basis of 1 χ 105 cells per cm2 of leather.

The sample thus inoculated is arranged in an agar medium cast in a Petri dish and itself inoculated with the suspension of corresponding microbial moulds.

The whole is incubated at 30 °C in a thermostated incubator.

Mould development on the leather and the agar medium is observed.

In a first series of tests, a leather tanned with chrome salts, and commonly referred to as wet-blue leather is impregnated with a solution containing an antibacterial compound, either according to the invention or, by way of comparison, with a known and commonly employed compound, namely a benzothiazole derivative marketed under the name Busan.

The lanthanum content, expressed as lanthanum oxide, or the Busan content is 0.4 %.

The results are collated in the table below: Another series of tests was carried out according to the same protocol, but using hides pretanned with an aluminium solution, referred to as BSH hide.

Thus, it was observed that the hide impregnated by 0.4 % of lanthanum (expressed as La2O3) with lanthanum acrylate is 75 % invaded after 6 days, and that impregnated with a solution of lanthanum acrylate in acrylic acid is 50 % invaded after 10 days and 75 % invaded after 24 days, while a hide not comprising antibacterial agents is 100 % invaded after 3 days.

These tests were also carried out with hides which 10 had undergone a vegetable tanning. They showed that the mixture of lanthanum acrylate and acrylic acid enables invasion by moulds to be delayed by several days (approximately 6 days) under the test conditions, whereas these hides untreated are invaded very rapidly (1 day).

Claims (15)

1. Process for the antifungal and antibacterial treatment of hides, characterized in that it consists in treating them with a treatment bath comprising at least one lanthanum or cerium salt.

2. Process according to Claim 1, characterized in that the lanthanum or cerium salt is a salt which is soluble or dispersible in water, selected from the group comprising the nitrates, halides, sulphates and organic salts .

3. Process according to Claim 2, characterized in that the organic lanthanum or cerium salts are vinylcarboxylic or organosulphonic acid salts or gluconates .

4. Process according to Claim 3, characterized in that the vinylcarboxylic acid salts are acrylic acid or methacrylic acid salts.

5. Process according to Claim 4, characterized in that the treatment bath contains a free vinylcarboxylic acid.

6. Process according to one of the preceding claims, characterized in that the mass of lanthanum or cerium, expressed as oxide, added for treatment of the hides is between 0.02 % and 1.25 % of pelt, and preferably between 0.04 % and 1.25 %.

7. Process according to one of the preceding claims, characterized in that the mass of vinylcarboxylate anion and/or of vinylcarboxylic acid, expressed as free vinylcarboxylic acid added for treatment of the hides is between 0.5 and 5 % of pelt, and preferably between 1 % and 3 % of pelt.

8. Process according to one of the preceding claims, characterized in that the antifungal and antibacterial treatment bath is used in combination with one of the hide treatment baths.

9. Process according to one of the preceding claims, characterized in that it consists in treating tanned or pretanned hides.

10. Hides, characterized in that they contain lanthanum or cerium.

11. Hides according to Claim 10, characterized in that they contain vinyl groups in monomer or polymerized form.

12. Hides according to Claim 10 or 11, characterized in that the lanthanum or cerium content expressed as oxide is between 0.04 % and 1.2 % relative to the dry matter.

13. A process according to claim 1 for the antifungal and antibacterial treatment of hides, substantially as herein before described.

14. A treated hide whenever obtained by a process claimed in a preceding claim.

15. A hide according to claim 10, substantially as herein before described.