GB2479052A

GB2479052A - Methods and kits for treating or preserving animal skins

Info

Publication number: GB2479052A
Application number: GB201104866A
Authority: GB
Inventors: Neil Charles Pritchard; Robert Anthony Burrow; Troy James Mcparland
Original assignee: NPN INTERNAT Ltd
Current assignee: NPN INTERNAT Ltd
Priority date: 2010-03-26
Filing date: 2011-03-23
Publication date: 2011-09-28
Also published as: AU2011201346A1; GB201104866D0; NZ584249A

Abstract

A method of preserving an animal skin or hide before completion of a tanning step is characterised by:(i) applying a compound selected from tris (hydroxymethyl) phosphine `X' compound (THPX), tetrakis (hydroxymethyl) phosphonium `X' salt, oxazolidine and glutaraldehyde (or derivative or modification thereof) to the animal skin or hide, wherein the compound has a functionality as a preservative for the animal skin or hide and wherein the application of the compound to the animal skein or hide replaces conventional salting such that conventional salting is not performed. A method of treating an animal skin may comprise step (i) as identified above and (ii) applying a fungicide and (iii) applying a non-swelling acid in sufficient quantity to maintain the pH of the skin to or below pH 4.0; kits for performing this method are also disclosed and claimed. The THPX compound may be THPS (tetra hydroxymethyl phosphonium sulfate). The animal skin may be sheep skin.

Description

METHOD OF PRESERVING ANIMAL SKIN OR HIDE

TECHNICAL FIELD

This invention relates to a method of preserving an animal skin or hide prior to completion of tanning.

BACKGROUND ART

Conventional salting of animal skins or hides has been used for centuries to temporarily preserve skins before they are tanned.

Preservation is important to prevent the skins from rotting, or being subject to bacterial or fungal growth during their storage or transport before tanning commences. Often, it can be months or years before the skins are tanned, and therefore preservation methods need to ensure the skins are well kept.

Recent advances in technology have overcome many of the current problems associated with the skin tanning industry, including avoiding the need for dangerous or environmentally unfriendly chemicals used during processing steps.

However, conventional salting of animal skins remains a problematic step which has yet to be effectively addressed.

After processing the anima' skins using conventional salting methods, the anima' skins can be stored for extended lengths of time. For examp'e, the animal skins may be intended for processing in other countries and require shipping overseas.

Once the skins are received by the tanner, the salt must be removed by physica' shaking and 1 or by washing. This salt or salty water (brine) is very difficuft to dispose of and is an increasing problem for tanners world wide.

Furthermore, the salts used for conventional preservation, typically sodium chloride (NaCI), is an environmental pollutant. These salts need to be removed before tanning commences which represents a major problem for tannenes. Disposing of the salt after t is washed from the skins is often difficult due to it being a pollutant and as a large percentage of tanneries are located inland.

Furthermore, the saft used for conventional preservation can be corrosive. This may damage plants and equipment used and potentially damage any surface the salt contacts during processing.

Once the salt is removed from the skin it is essentially still a raw skin. Therefore the cost of salting is not further utilised because it has to be washed out. Only once the salt has been removed is the skin ready for fleshing, scouring or pickling for tanning.

Following conventional salting, storage, and then subsequent removal of the salt, the skins typically need to be degreased to remove excess grease from the skins.

Degreasing adds an additional step to the process, and currently, often requires solvents or other toxic chemicals such as glutaraldehyde to avoid shrinkage caused by the high temperatures used in the degreasing step. It wou'd be advantageous to find a solution that, in addition to addressing the problems outlined above, at least also partially addresses the need to degrease animal skins.

It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.

All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. It wiU be clearly understood that, although a number of prior art publications are referred to herein, this reference does not consttute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country.

Throughout this specitcaton, the word "comprise", or vanabons thereof such as "comprises" or "comprising", wiU be understood to imply the inclusion of a stated element, nteger or step, or group of elements integers or steps, but not the exclusion of any other element, nteger or step, or group of elements, integers or steps.

Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.

DISCLOSURE OF INVENTION

According to one aspect of the present invention there is provided a use of THP'X', wherein X' is an anion, wherein the new use of THP'X' is to replace a conventional salting step in the treatment of an animal skin or hide before completion of a tanning step.

According to a further aspect of the present invention there is provided a method of treating an animal skin or hide before completion of a tanning step, characterised by the step of: applying THP'X' to the animal skin or hide, wherein X' is an anion, and wherein THP'X' replaces conventional salting.

According to a further aspect of the present invention there is provided a method of treating an animal skin or hide before completion of a tanning step, characterised by the steps of: a) applying THP'X' to the animal skin or hide, wherein X' is an anion, to replace the need for conventiona' sa'ting; and b) applying a fungicide to the animal skin or hide; and c) applying a non-swelling acid to the animal skin or hide, in sufficient quantity to maintain the pH of the animal skins or hides to or below pH 4.0.

According to a further aspect of the present invention there is provided a kitset for treating animal skin or hide before completion of a tanning step substantially as described above, wherein the kitset includes a) THP'X' to the animal skin or hide, wherein X' is an anion, and; b) a fungicide; and c) a non-swelling acid.

Throughout the specification, the term "THPX" should be taken as meaning any tris (hydroxymethyl) phosphine X' compounds or its derivatives or tetrakis (hydroxymethyl) phosphonium X' salt or its derivatives, or any organic tanning agent and / or modifications or derivatives of oxazoUdines or glutaraldehydes.

Preferably X' is any compatible anion. The advantage of using an anion as X' is that it is like'y to aid in the solubility of the compound. For examp'e, X may be an anion such as sulphate, chloride, bromide, phosphate, nitrate, or fluoride.

Most preferably, X' is a sulphate (i.e. THPS). A commercially available THPS considered particularly useful is Albrite AD. However, the inventors acknowledge that other sources of THPS may be used without departing from the scope of the invention.

Reference shah now be made to THP'X' as being THPS as the inventors recognize this as a preferred type of THP'X'. However, persons skified in the art wil' appreciate that this is not meant to be imiting and other THP'X' compounds may readily be used.

Numerous documents disclose the use of THPS as a pre-tanning agent or finishing agent to use on skins which have been pre-salted for preservation purposes.

However, it has never been previously identffied that THP'X' may be used to completely replace the conventional salting requirements (and its associated disadvantages) whilst still providing a preservation step, which is needed in the industry.

Conventional salting typicaly includes washing the skins in water and then adding dry salt to preserve them prior to tanning. For example, skins can be oaded into a processing vessel whereafter washing and draining, a combination of 35% salt, 0.5% boric acid and 0.25% Sodium Metabisulphite and run until the salt fully penetrates the skins.

Despite THPS compounds being used in the tanning industry for over 20 years, it has not yet been identified that THPS compounds have the ability to act as a long term preservative to completely rid the need for conventional salting. Therefore, the inventors have identified a new use of these compounds, whilst avoiding the problems of conventional salting as previously discussed.

The use of THPS to replace salting may have the following advantages: -eliminates the need to remove preservation compounds such as salt prior to completion of tanning. This may help to avoid problems associated with conventional salting -these can include pollution.

-Avows for long-term preservation which is essential for animal skins or hides that require lengthy transport (e.g. shipping).

-Passes the LASRA (MM2) industry test in which the skins remain stable and unaffected by fungal and bacterial damage after being subjected to 90 days at 30°C in a tropical chamber. This is equivalent to being stored for 9 months at normal conditions.

-Reduces the number of steps needed in the overall tanning process, thereby making processing more economical (e.g. less drying).

-THPS helps in the degreasing of skins and reduces the reliance on solvent degreasing. Again this represents a saving in chemicals and time.

-The use of this novel process means that the skin may have a shrinkage (Ts) of at least 75°C. For example, this means that the skins may be aqueously degreased using detergents and hot water washes at 50°C, without the need for solvents or glutaraldehyde.

-Comparable results to conventional salting in terms of chemical costs -THPS is already used in the field, and is generally well-trusted by users, as well as being relatively safe to use subject to the wearing of neutral protective equipment. Furthermore THPS complies with the regulatory requirements of most countries.

Prior to processing by the purchasing tanner, the skins can be washed and this water could be recycled.

Preferred aspects and embodiments of the present invention are now discussed.

Any values in ranges discussed should be understood to be inclusive of the threshold values given.

The animal skin or hide to be treated may be from sheep, goat, cow, pig or other animal skin.

Most preferably, the animal skin to be treated is a sheep skin. Salt can accumulate in the wool, and be particularly difficult to remove. Using THPS in lieu of salt may simplify the processing of the sheepskin as the THPS may help to partially tan the skin.

Reference shall now be made throughout the remainder of this specification to the animal skins or hides being sheepskins. However, this is not meant to be limiting and any commercial valuable animal skin or hide may be used with the present invention.

Preferably, the method of treating is to preserve the sheepskin prior to tanning.

The inventors have found that the THP'X' may be used to allow long term storage of the skin or hide.

For example the inventors conducted a study that showed the THP'X' preserved skins did not grow any bacteria or fungus (and were in good condition overall) following an incubation period of 90 days at 30°C (according to LASRA test).

The LASRA test exemplifies that the preservation of sheepskins according to the present invention may be able to withstand extreme conditions during storage or transport.

Preferably, the treatment step using THPS is conducted before a conventional tanning step.

Conventional tanning may include, for example, contacting the sheepskins with one or more tanning agents such as vegetable tannages, mineral tannages such as chrome salts, organic salts or synthetic tannages.

The nventors have found that THPS compounds may help to actuay partiafly tan sheepskins. Therefore, it should not be considered beyond the scope of the invention that THPS in the present invention may be used as part of the tanning process itself.

Although THPS would not normally be used to complete the tanning step, it may be within the scope of the invention that THPS also is used to substantially tan the skin or hide as well as providing a preservative effect.

Particularly preferred embodiments of the treatment method are now further described. The inventors acknowledge it is not beyond the scope of the invention to alter these conditions, depending on the results required by the user of the present invention.

Preferably, the method is conducted in a tanning vessel, for example a drum, mixer or dolly.

Preferably, the treatment steps are conducted at a temperature from 5 to 40°C.

This temperature range is preferred as it is least likely to result in damage to the skins.

Most preferably, the treatment steps are conducted at a temperature of approximately 20°C. as This temperature was found to not damage the skins and no energy was required to heat the water.

Preferably, the sheepskin is processed in water for 10 to 120 minutes.

Preferably, prior to step a), the skins are washed and run in water for 30 minutes.

Preferably, the water is drained from the sheepskin before the THPS is applied.

Preferably, 10 -200 grams of THPS per skin I or Kg of animal skin is apped. After treating the skins with THPS, the temperature of which shrinkage can occur (Ts) should be in excess of 75°C.

Preferably, the THPS is processed with the sheepskin for 10 to 120 minutes.

Preferably, a non-swelling acid (e.g. Fortan4OTM) is applied to the skins before step c).

The fungicide applied in step c) may be any agent capable of killing or inhibiting growth of fungal spores. One such fungicide that the inventors find particularly useful is -4-Chlor-M-Cresol 2-Phenylphenol (for example, that marketed as Preventol WBLTM). However, the inventors acknowledge that other fungicides/microbicides may be used without departing from the scope of the invention.

Preferably, the fungicide is processed with the animal skin or hide for 10 to 180 minutes.

The inventors have identified that an acid may be needed to maintain the sheepskins between a pH of 1 and 4.

Preferably, the sheepskin is maintained between pH 3.0 and 4.0. Most preferably the sheepskins are maintained at approximately pH 3.5.

Throughout the specification the term "non-swelling acid" should be taken as meaning any acid or combination of components including an acid which when applied to a skin or hide does not require the need for salt to prevent swelling as a result of adding the acid.

The inventors have found that many acids cause swelling of the skins which require the addition of salt to address. This defeats the purpose of the present invention which is to avoid the need for salt in the preserving step of skins or hides.

Most preferably the non-sweUing acid is a combination of components that when added to the skins, result in the pH of the skin being lowered.. For example, the inventors have found that a commercially available product (Fortan4OTM) works particularly well as a "non-swelling acid" in the present invention. Fortan40' includes acidic sulphates, glycol sulphates, formic acid (<70%) and water (to 100%). The inventors have found this type of acid to be particularly useful in reducing the pH of the skins without causing any swelling to the skins. It would be readily apparent to a skilled person that other types of non-swelling acids, may work in a similar fashion to Fortan40', and thus should not be considered beyond the scope of the invention.

A skilled person would be able to easily determine whether a given substance acts as a non-swelling acid by applying it to animal skins and recording whether it acts as a pH regulator (lowering the pH) and does not cause the skins to swell.

This is in comparison to other types of acids, such as formic acid, sulphuric acid, hydrochloric acid, or boric acid, all which can cause the sheepskin to swell. To address the swelling issue, one can add salt to prevent swelling. However, this defeats the purpose of the present invention which is to completely rid the need for salting of the sheepskins.

Furthermore, non-swelling acids may be relatively safe to use (e.g. low corrosiveness) compared to other acids which can be harmful to handle (i.e. corrosive on skin).

Additionally, the non-swelling acid have been found by the inventors to provide long-term pH control of the sheepskins (e.g. over 90 days). This time period may be useful for typical preservation requirements such as shipping etc. This is in comparison to other types of acids where the inventors found these to only maintain the pH at the desired level for 2 to 3 weeks and only with the addition of salt.

This may be disadvantageous as shifting of the pH range outside the preferred range (pH 3.0 -4.0) may lead to bacterial growth or other issues that arise during long term storage or transport.

Preferably, the non-swelling acid is applied to the sheepskin prior to adding the fungicide (i.e. after the THPS treatment). This may help to maintain the pH of the sheepskins during treatment to the preferred pH of 3.0 to 4.0. Maintaining the pH at this level may increase the effectiveness of the the fungicide.

Treating the sheepskin after the fungicide treatment step b) helps to maintain the final pH of the sheepskins at pH 3.0 to 3.5.

Preferably, the acid is processed with the sheepskin for 10 to 60 minutes at a time.

This process may need to be repeated in order to reduce the pH of the skins to or below pH 4.0.

After the process described above is complete, the float (i.e. the solution) is drained from the skins, which may then be packed (wet) for storage or transport.

BRIEF DESCRIPTION OF DRAWINGS

Further aspects of the present invention will become apparent from the ensuing description which is given by way of example only and with reference to the accompanying table in which: Table 1 is a particularly preferred method of treating animal skins or hides; and Table 2 shows results from testing the processed skins for mould resistance using LASRA method.

BEST MODES FOR CARRYING OUT THE INVENTION

Example 1:

The present invention provides a new use of THP'X' (such as THPS) to replace conventional salting step in the treatment of animal skns or hdes (such as sheepskins) before completion of a tanning step.

The preferred method is described below, and shown in Table 1.

The skins are processed in a tanning drum, processor or dolly.

The animal skin to be treated is sheep skin prior to tanning commencing.

Water is applied to the sheep skin which is then processed for 30 minutes at 20°C.

The water is then drained from the skin. Because of the wool texture a substantial quantity of water remains in the processing vessel I skins.

THPS (Albrite AD) is added to the float and processed for 30 minutes at 20°C.

Following this, two rounds of non-swelling acid are added to the skins each for 30 minutes at a time. This lowers the pH to approximately 3.5.

Following acid treatment, a fungicide is added to the skins and processed for 60 minutes at 20°C. Following fungicide run, additional non-swelling acid is added again for approximately 10 -15 minutes at a time to lower the pH down to approximately 3.5.

Process % kg 11 °C Run Rest (pH Load skins Add 500.00 ________ Water 20 0 30' ______ _____________ Drain per skin 50.00 5,000.0 Aibrite AD 30' Pius 6.60 739.0 Fortan -40 3tY _____ pH3.36 Pius 6.60 1478.0 Fortan -40 30' _____ pH 3.31 Penetration OK Hus 0.01 4,480.0 Prevento WB -L 60' _____ ph 3.71 Pius 500.0 Fortan -40 10' _____ pH 3.64 Pius 1000.0 Fortan -40 15' _____ pH 3.40 Tab'e 1: A particuary preferred method of treating anima' skins or hides.

Example 2:

Three samples of woolskin were received for mould resistance testing using the LASRA method is shown below. After three months the test was stopped according to the standard practice. The results follow:

___________ _______________________________

Days Protection Sample ___________ Duplicate 1 Dup'icate 2 1 90+ 90+ 2 90+ 90+ 3 90+ 90+ Tab'e 2: Resufts from testing the processed skins for mou'd resistance using LASRA method (MM2).

The three month (or 90 day) accelerated fungal resistance test corresponds to approximately nine months exposure of the eather under normal circumstances.

The LASRA (MM2) test wil continue on these samples (currently ongoing) unti they fail to determine at greater depths the effectiveness of the method described in the present invention.

These resuts indicate that the samples have passed the test, and indicates the effectiveness of the novel method.

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof as defined in the appended claims.

Claims

WHAT IIWE CLAIM IS: A method of preserving an animal skin or hide before completion of a tanning step, characterised by the step of applying a compound to the animal skin or hide,wherein the compound is selected from tris (hydroxymethy) phosphine X' compound, tetrakis (hydroxymethyl) phosphonium X' salt, oxazolidine and glutaradehyde or derivative or modification thereof which is structurally similar to one of the above compounds, wherein the compound or derivative or modification thereof has a functionality as a preservative for the animal skin or hide to which it is applied, and wherein the application of the compound or derivative or modification thereof to the animal skin or hide replaces conventional salting such that conventional salting is not performed.
2. A method of treating an animal skin or hide before completion of a tanning step, characterised by the steps of: a) applying the chemical as daimed in claim 1 to the animal skin or hide to replace the need for conventional salting such that conventional salting is not performed; and b) applying a fungicide to the animal skin or hide; and c) applying a non-swelling acid to the animal skin or hide, in sufficient quantity to mantam the pH of the animal skins or hides to or below pH 4.0.
3. A method according to any one of dams 1 or 2 wherein the X' in tetrakis (hydroxymethyl) phosphonium X's an anion.
4. A method according to any of the above claims wherein x' s selected from the group including sulphate, chloride, bromide, phosphate, nitrate, and fluoride.
5. A method according to any one of claims I to 4 wherein X' is sulphate.
6. A method according to any one of claims 1 to 5 wherein the treatment is used to preserve the animal skin or hide prior to tanning.
7. A method according to any one of claims 1 to 6, wherein the use of the chemical is applied before a tanning step commences.
8. A method according to any one of claims 1 to 6, wherein the use of the chemical partially tans the anima' skin or hide.
9. A method according to any one of claims 2 to 8, wherein steps a) to c) are conducted at a temperature from 5 to 40°C.
10. A method according to any one of claims 2 to 9, wherein any one of steps a) to c) are conducted at a temperature of approximately 20°C.
11. A method according to any one of claims 2 to 10, wherein water is applied to the animal skin or hide prior to applying the chemical.
12. A method according to claim 11 wherein the animal skin or hide is processed with water for lOto 120 minutes.
13. A method according to either daim 11 or claim 12 wherein the water is at least partially removed from the animal skin or hide before the the chemical is applied.
14. A method according to any one of claims 1 to 13 wherein 10 -200 grams of the chemical is applied per skin or kg of animal skin or hide.
15. A method according to any one of claims 1 to 14 wherein the chemical is processed with the animal skin or hide for 10 to 120 minutes.
16. A method according to any one of claims 2 to 15 wherein the fungicide applied in step (c) is any agent capable of killing or inhibiting growth of fungal spores.
17. A method according to any one of claims 2 to 16 wherein the fungicide is -4-Chlor-M-Cresol 2-Phenylphenol or a derivative thereof.
18. A method according to any one of claims 2 to 17 wherein the fungicide is processed with the animal skin or hide for 10 to 180 minutes.
19. A method according to any one of claims 1 to 18 wherein the animal skin or hide is maintained between a pH of 3.0 and 4.0.
20. A method according to any one of claims 2 to 19 wherein the non-swelling acid is formic acid.
21. A method according to any one of claims 2 to 20 wherein the non-swelling acid is also applied to the animal skin or hide prior to step b).
22. A method according to any one of claims 20 to 21, wherein the non-swelling acid is processed with the animal skin or hide for 10 to 60 minutes at a time.
23. A method according to anyone of claims 1 to 22 wherein the animal skin to be treated is a sheepskin.
24. A use of the chemical according to the method described in any one of claims 1 to 23, wherein the new use of the chemical is to replace a conventional salting step in the treatment of animal skin or hide before completion of a tanning step.
25. A kitset for preserving an animal skin or hide before comp'etion of a tanning step, for use in the method described in any one of claims I to 23, wherein the kitset includes (a) the chemical as claimed in any of the claims above; (b) a fungicide; and (C) a non-swelling acid in sufficient amounts to maintain the pH of the anima' skins or hides to or below pH 4.0.
26. A method of treating an animal skin or hide before completion of a tanning step wherein conventional safting is not performed, substantially as described with reference to the description and Examples 1-2 as shown in the Best Modes section.