The present invention relates to vegetable tanning methods, and more particularly to a method for producing a sustainable leather free of chromium, free of heavy metals and benzidine dyes, using several vegan by-products from the Persea genus plant.
The tanning of hides and skins is one of the oldest processes of mankind. There are several types of tanning, among them, the most known and used are vegetable tanning, which uses only tannins, and vegetable tanning, which uses only tannins, and vegetable tanning, which uses only tannins, and chrome tanning, which may include the use of tannin in some stages of processing.
Vegetable tanning has several advantages over chrome tanning, such as: vegetable tanning is more environmentally friendly as it does not use chrome or heavy metals, which means that it produces a hide or leather that can be recycled, and the colors produced by vegetable tanning are rich, warm tones that look natural.
The raw materials used for vegetable tanning are natural tannins, available in liquid or powder form, which are obtained from various parts of plants such as wood, bark, fruit, pods, and leaves.
Therefore, it is desirable to use vegetable raw materials that are abundantly available and economical such as fruits in a vegetable tanning method.
The plant genus Persea and its many species are used primarily as one of the most nutritious foods that have ever existed in the world; it is a plant with an abundant content of oils, tannins, and antioxidants and that proliferates relatively easily. In Mexico alone 2,029,886 tons of avocado were produced in 2017.
Due to the large amount of avocado produced, not all of the production is consumed and every year thousands of tons of avocado are dumped in landfills around the world, which generates greenhouse gases as it decomposes.
Therefore, avocado comprises an ideal raw material that could be exploited in a vegetable tanning method.
In view of the above, the applicant developed a vegetable tanning method specially designed to take advantage of the use of avocado and seed of the genus Persea, in any variety of species, as raw material, preferably by-products of the food industry.
The basic raw materials of the method of the present invention are raw hides and skins of cattle, goats, and others, of all ages and various breeds, and a natural tanning agent obtained from the seed, pulp, and crust (peel) of the avocado genus Persea, for which the applicant developed a specific method to obtain it.
The final product can be used to manufacture leather seats for automobiles, airplanes, boats and any type of vehicle, all types of shoes, boots, handbags, briefcases, leather goods, computer components and their cases and accessories, living rooms, and sofas, chairs, belts and garments to be identified as hides and skins with a sustainable and environmentally friendly tanning process that starts with renewable materials such as avocado Persea genus and general livestock hides and skins that are existing by-products derived from the food industry.
The hide and leather produced by means of the method of the present invention is sustainable, free of chromium, free of heavy metals and benzidine dyes.
It is therefore a main objective of the present invention, to provide a vegetable tanning method especially designed to benefit from using as raw material, avocado and seed of the Persea genus in any variety of species, preferably by-products of the food industry.
Another main purpose of the present invention is to provide a tanning method of the above-described nature, which uses as basic raw materials raw hides and skins from cattle, goats, and others, of all ages and various breeds, and a natural tanning agent obtained from the seed, pulp, and peel of the avocado genus Persea.
It is an additional purpose of the present invention to provide a natural tanning agent obtained from the seed, pulp, and rind (peel) of the avocado genus Persea and the method for its preparation.
It is yet an additional purpose of the present invention, to provide a skin or leather produced by means of the vegetable tanning method of the present invention, which are sustainable, free of chromium, free of heavy metals and benzidine dyes.
These and other objectives and advantages of the present invention will become evident to persons having ordinary skill in the trade by means of the following detailed description of the invention.
The method of the present invention uses as raw material raw hides and skins from cattle, goats, and others, of all ages and various breeds, and avocados and seeds of the genus Persea in any variety of species, preferably by-products of the food industry, which upon receipt from the supplier were stabilized at room temperature (preferably 25° C.) for 24 hours. Subsequently, the seeds were washed before being used in the method of the present invention.
The method of the present invention will now be described in relation to a preferred mode thereof, wherein the method for producing sustainable leather of the present invention comprises the following stages:
Preparation of the Natural Tanning Agent (
Production of “Tanning H”.
Production of “Paste H”.
Production of “HCP Tanning Agent”
Production of “AL50 OIL”
Leather Production (
The raw leather is processed by a method comprising the following steps:
The parameters of the leathers measured in the first quality test and in the second quality test are measured according to the standards in Table 2:
In another embodiment of step b) pertaining to the leather production steps, the following vegetable ingredients: tanning agent H, paste H and HCP tanning agent are added not independently, but as a mixture of natural ingredients previously mixed by stirring for 5 to 30 minutes in the following percentages (+/−15% to obtain a total of 100%):
Tanning agent H: 33.3%+−15%.
Paste H: 33.3%+−15%.
HCP Tanning Agent: 33.3%+-15%.
In this approach, the amount of the mixture to be added in step b) is between 3% and 25% depending on the required strength and softness properties.
Analysis of the Leather Produced by the Method of the Present Invention.
The analysis of the chemical components of the leather produced by the method of the present invention was carried out by Fourier transform infrared spectroscopy (FT-IR). This technique is based on molecular vibration, making it very useful for the analysis of compounds of natural origin; A comparative analysis of conventional leather samples compared with leather produced with the method of the present invention, shows a remarkable difference: the method of the present invention generates in the leather the following peaks in the infrared curves, which are intrinsic only in leather tanned with plant derivatives of the genus Persea:
The data shown in the above table comprise a “chemical identity card” which is useful for identifying the leather produced by the method of the present invention.
Ideally, the analysis of the chemical components of the leather produced by the method of the present invention is carried out using a Fourier Transform Infrared Spectrophotometer (FT-IRJ) (Thermo Scientific Nicolet Model iS10) with a MIR source and with the SmartOrbit ATR/Avatar module. The software used is OMNIC 8.2 (Thermo Scientific), analyzing spectra obtained in the infrared region between 4000 cm−1 and 400 cm−1.
Forty kilograms of Persea fruit at various stages of maturation and 40 kg of seeds were received. They were left to stabilize for 24 hours at an ambient temperature that fluctuated between 24 and 26 degrees.
Subsequently, the “tanning agent H” was elaborated.
The tanning process was carried out for the 50 hides with these ingredients by adding 298 liters of water at a temperature of 45 degrees Celsius for a time of 2.8 hours in a reactor with a speed of 6 revolutions per minute and for the 100 hides by adding 490 liters of water at a temperature of 45 degrees Celsius for a time of 2 hours in a reactor with a speed of 6 revolutions per minute.
Subsequently, the ingredient AL50 OIL was manufactured with 24 kilograms of 100% pure Persea oil in 95 liters of water at 50 degrees Celsius and 5 kilograms of anionic emulsifier, stirring for 15 minutes. Of this emulsion, 41.060 kilograms were used for example 1 of 30 50 hides and 63,210 for example 2 of 100 hides.
Dyeing Process.
The 50 hides were dyed with 0.830 kilograms of beige dye in a bath of 298 liters of water at a temperature of 45 degrees Celsius in a reactor of 6 revolutions per minute for 1 hour using 5.060 kilograms of formic acid as a fixing ingredient.
The 100 hides were dyed with 22.050 kilograms of black dye in a bath of 490 liters of water at a temperature of 45 degrees Celsius in a reactor of 6 revolutions per minute for a period of 1 hour using 11.025 kilograms of formic acid as a fixing ingredient.
Both examples were produced under the conventional drying, softening, and finishing system described above.
Analysis of the hides obtained by Fourier transform infrared spectroscopy (FT-IR) showed that they comply with the “chemical identity card” described above.
Filing Document | Filing Date | Country | Kind |
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PCT/MX2020/050019 | 7/15/2020 | WO |
Publishing Document | Publishing Date | Country | Kind |
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WO2021/010815 | 1/21/2021 | WO | A |
Number | Date | Country |
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109207654 | Jan 2019 | CN |
2862944 | Apr 2015 | EP |
Entry |
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Extraction of oil and phenolic retanning agent from Avocado seeds (Jan. 23, 2019). |
International Search Report and Written Opinion from corresponding Mexican Application No. PCT/MX2020/050019, Dec. 3, 2020. |
Number | Date | Country | |
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20220259683 A1 | Aug 2022 | US |
Number | Date | Country | |
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62874602 | Jul 2019 | US |