DESC:Field of invention
The present invention relates to a method of preparation of biodegradable composite material such as bio-composite leather using fungal fibres. More particularly, the invention relates to preparation of bio-composite leather by blending fungal fibres, preferably, mushroom fibres extracted from mushroom fruiting bodies and a biodegradable polymer. The invention also relates to the biodegradable composite material obtained using the above method.
Background

Leather has been a coveted material throughout human history and from ancient to modern times, leather goods have retained their allure and continue to make a strong market demand. At present time, natural animal leather or synthetic leather available in the market is made up of non-degradable polymer material. The production of natural leather involves animal cruelty and additionally, the post-processing method of making leather from hide involves harsh chemical treatment resulting in large amount of sludge water discharge thus, polluting the water bodies. These leather processing chemicals are considered highly toxic to the environment and is detrimental to our ecosystem. On the other hand, polymer-based synthetic leather material is produced from elastomeric material or plastic materials which are nonbiodegradable, with high shelf life creating a burden on our planet.
In recent years, sustainability has become a key consideration in guiding choices, with individuals prioritizing products that align with the environment values and promote responsible practices. Sustainable and ethically sourced leather options can be a great alternative to existing choices available. With extensive questioning on natural animal leather or synthetic leather there is an urgent need for ecological sustainable, economical and socially responsible alternatives.
The sustainable substitutes like biodegradable composite material or bio-composite leather are cruelty-free, environment friendly, non-polluting, bio-degradable and durable thus, provides an alternate choice for use in furniture, garments, footwear etc. Also, the vegan based bio¬leather options can be an apt choice for people with allergies due to absence of allergens in them.
State of the art also suggested method of production of fungal bio-leather. For instance, IN202411011490 discloses fungal strains and methods of producing fungal biomaterial from fungal mycelium. The method requires a growth period of approximately 40-50 days.
Consequently, mass production of such biomaterial or bio-leather becomes a challenge due to low productivity.
Hence, there is a need for sustainable alternatives which overcomes the challenges related to existing leather variants and which are cost-effective, scalable, durable, customizable, environmentally friendly and allows high productivity.
Summary
The present invention relates to a method of preparation of biodegradable composite material such as bio-composite leather from fungal fibres, preferably, mushroom fibres. According to the invention, bio-composite leather is prepared by blending fungal fibres, preferably, mushroom fibres extracted from mushroom fruiting bodies and a biodegradable polymer. The present invention also relates to the biodegradable composite material produced from fungal fibres preferably mushroom fibres or mushroom fruiting body fibres using the method disclosed herein.
It is an object of the present invention to provide a method to produce a fully biodegradable composite material such as bio-composite leather from mushroom fruiting body fibres.
It is another object of present invention to produce a bio-composite leather which is lightweight and possess characteristics such as breathability, flexibility, high tensile strength, and tearing strength under stress. Said bio-composite leather has higher mechanical strength and flexibility than commercially available synthetic leather.
It is yet another object of the present invention to produce a bio-composite leather that simulates commercial leather-like material in terms of physical and mechanical properties.
It is yet another object of the present invention to produce a bio-composite leather with enhanced aesthetic properties, hydrophobicity, stain-repellent properties, and with higher oil and chemical resistance.
It is yet another object of the present invention to provide a method or process to produce a biodegradable composite material like bio-composite leather using high quantity of fibres extracted from fruiting body of mushroom with higher extraction efficiency and higher productivity.
It is yet another object of the present invention to provide a method for making a biodegradable composite material like bio-composite leather from mushroom fruiting body fibres which is scalable. The bio-composite leather can be produced continuously in production line and do not require a batch process production method, leading to a reduction in cost up to 50% and production time is reduced to 6-7 days as compared to 3-4 weeks in case of mycelium bio¬leather thus saving the time, cost and increasing the efficiency.
It is yet another object of the present invention to provide a method or process to develop biodegradable composite material like bio-composite leather from mushroom fruiting body fibres using a green approach.
The aforesaid objects of the present invention are achieved by the present invention. In a preferred embodiment of the present invention, the method of preparation of biodegradable composite material comprises following steps:
a) Fibres are extracted from mushroom fruiting bodies and the extracted fibres are mixed with a biodegradable polymer, preferably, Polyvinyl Alcohol (PVA). The extracted fibres are mixed in the range of 30 to 60% by weight to obtain a mixed fibre.
b) A plasticizer formulation is added in the mixed fibre in the weight range of 40 to 70 % weight of the polymer, wherein the preferred plasticizer formulation used in this invention comprises glycerol 30-50 %, propylene glycol 10-20 %, and polyethylene glycol (Mw 200) 10 to 20 %.
c) The mixed fibre containing plasticizer formulation is blended to obtain a blended fibre solution.
d) The blended fibre solution is layered on trays and dried in a hot air oven at a temperature in the range of from 50 to 80?, preferably 60? to obtain a dried fibre sheet.
e) The dried fibre sheet or composite sheet obtained is heat pressed.
The present invention aims to achieve an overall green approach and therefore water is used as a solvent to dissolve biodegradable polymer. The blending mushroom fibres obtained in ‘step a)’ with a biodegradable polymer is preferably done in a high shear mechanical mixer. Under high shear rate these fibres are uniformly mixed and dispersed in the polymer phase.
The mushroom species preferably used in the present invention is Dichomitus sp.
Furthermore, for extracting the mushroom fibres from the fruiting body of the mushroom, the following steps are preferably performed:-
a) Breaking the fruiting body into small pieces;
b) Boiling the smaller pieces in water for 20-40 minutes, preferably 30 minutes;
c) Grinding the small pieces of fruiting body in high speed mixer;
d) Filtering and drying the ground fibres in hot air oven in a temperature range of 60°C to 100°C, preferably at 80°C, for 8 hours to 24 hours, preferably left for 12 hours overnight for complete drying to remove the water-soluble impurities present in the fruiting body and obtain dried fibres;
e) Soaking the dried fibres in ethanol for 18 to 48 hours, preferably 24 hours to partially deacetylate and deproteinize chitinous fibres and remove organic soluble impurities;
f) Filtering and drying in hot air oven in a temperature range of 40°C to 80°C, preferably at 50°C, for 8 hours to 24 hours, preferably 12 hours to completely evaporate ethanol from the fibres and to obtain dried mushroom fibres from the fruiting body of the mushroom,
These fibres so obtained from the fruiting body of the mushroom have very low density in the range of 0.03 to 0.6 g/cm3, crystallinity in the range 50 to 65%, low elongation about 7%, and high tenacity.
According to an embodiment, the bio composite leather sheet obtained from the above process is subjected to post drying processing. The post drying process comprises the steps heat pressing the composite sheet to flatten the sheet followed by microthinning. Microthinning precisely controls the thickness of the leather sheet and helps to provide uniform thickness to the leather sheet obtained. The composite sheet is further coated on the surface and heat pressed again to obtain a final finished material or a bio-composite leather.
The produced bio-composite leather possess high mechanical strength and flexibility that simulates commercial leather-like material in terms of physical and mechanical properties. The bio-composite leather has several uses, applications, and advantages in a variety of sectors like fashion and apparel, accessories and home goods, automotive interior components and medical and textile industry. The present invention eliminates use of extensive chemical processing and tanning process that is required for animal leather.
Brief Description of the Drawings
The present invention is described by way of embodiments illustrated in the accompanying drawings wherein:
Figure 1 is a flow diagram showing steps of preparation of bio-composite leather from mushroom fruiting body fibres.
Figure 2 illustrates parts of a mushroom body comprising a mycelium network, stipe, fruiting body and fruiting body fibres.
Figure 3 shows a schematic process of extraction of fibres from mushroom fruiting body.
Figure 4 shows steps of blending fibres obtained from mushroom fruiting body with biodegradable polymer to obtain a bio-composite sheet.
Figure 5 shows the steps of post processing of bio-composite sheet.
Figure 6 shows different types of bio-composite leather produced from mushroom fruiting body fibres and biodegradable polymer.
Detailed Description
The present invention relates to a method of preparation of biodegradable composite material such as bio-composite leather from fungal fibres, preferably, mushroom fibres. The present invention comprises preparation of bio-composite leather by blending mushroom fibres extracted from mushroom fruiting body and a biodegradable polymer.
In an embodiment of the present invention, a method of preparation of biodegradable composite material, the method comprising:
a. extraction of fibres of fruiting bodies of Dichomitus sp.;
b. blending with biodegradable polymer to obtain the biodegradable composite material.
In an embodiment of the present invention, the method of preparation of bio-composite leather further comprises of following steps as described in figure 1:
1. collection of mushroom fruiting bodies
2. extraction of fibres
3. blending with biodegradable polymer
4. uniform layering on metallic tray
5. hot air oven drying
6. post drying processing
In an embodiment of the present invention, the fruiting bodies are selected from the fruiting bodies of fungal strain, Dichomitus sp. deposited under MTCC 25684.
In an embodiment of the present invention, the extraction of fibres of fruiting bodies of Dichomitus sp. comprises the following steps:
a. breaking the fruiting bodies into small pieces;
b. boiling the smaller pieces in water for 20-40 minutes, preferably 30 minutes;
c. grinding the small pieces of fruiting body to obtain ground fibres;
d. filtering and drying the ground fibres at a temperature range of 60°C to 100°C, preferably at 80°C, for 8 hours to 24 hours, preferably 12 hours to obtain dried fibres;
e. soaking the dried fibres in ethanol for 18 hours to 48 hours, preferably 24 hours to partially deacetylate and deproteinize chitineous fibres and remove organic soluble impurities to obtain soaked fibres;
f. filtering and drying the soaked fibres at a temperature range of 40°C to 80°C, preferably at 50°C, for 8 hours to 24 hours, preferably 12 hours to completely evaporate ethanol from the fibres and to obtain dried mushroom fibres from the fruiting body of of Dichomitus sp. mushroom.
In an embodiment of the present invention, the biodegradable polymer is polyvinyl alcohol and is blended in step b) described above in the range of 30 to 60 % by weight. In preferred embodiment, in step b) a plasticizer is added to the blend of mushroom fibres and biodegradable polymer. The plasticizer is in the weight range of 40 to 70% by weight of the polymer and comprises glycerol 30-50 %, propylene glycol 10-20 %, and polyethylene glycol (Mw 200) 10 to 20 % by weight.
In an embodiment, the blend of mushroom fibres, biodegradable polymer and plasticizer is layered on trays and dried in a hot air oven at a temperature in the range of from 50 to 80?, preferably 60? to obtain a dried fibre sheet. Thickness of the layers is equal and range between 2-4 mm, preferably 1-2 mm. The dried fibre sheet or composite sheet obtained is heat pressed, followed by microthinning to preferably 0.5 mm to 1.5 mm. Microthinnig is the process of further reducing the thickness of dried fibre sheet and releasing moisture.
In an embodiment, post microthinning of the dried fibre sheet, the dried fibre sheet is coated with a surface coating solution which comprises polyvinyl alcohol 8-10 % by wt, glycerol 1 % by wt, colour pigment 0.1-0.5 % by wt in water. The sheet is further subjected to heat pressing to obtain a biodegradable composite material.
In an embodiment of the present invention, the biodegradable composite material is a bio-composite leather produced by the method described above.

The preparation of bio-composite leather are explained hereinbelow in detail.
According to a preferred embodiment, mushrooms of desired characteristics are either grown in laboratory or sourced from a vendor followed by collection of mushroom fruiting bodies as shown in figure 2. Fruiting bodies are used for extraction of mushroom fibres for further process. The species of mushroom preferably used in present invention is Dichomitus. Details of the specific fungal strain used are as follows:-
Scientific name Applicant’s code MTCC accession number
Dichomitus sp. A3 MTCC 25684
The step of extraction of fibres from mushroom fruiting bodies involves removal of impurities such as solid impurities and fibre isolation as described in figure 3. The removal of impurities also includes removal of nonfibrous hard part. The collected fibrous parts of fruiting bodies of the mushrooms are broken into small pieces and boiled in water. In a preferred embodiment, the broken fruiting bodies are boiled for 30 minutes in water.
The boiled small pieces of fruiting bodies obtained undergo grinding in a further step. The grinding is preferably performed in a high-speed mixer to convert the boiled fruiting bodies into small fibres. The fibres obtained after grinding are filtered and dried in hot air oven. In a preferred embodiment, the fibres are dried in hot air oven at 60°C to 100°C, preferably at 80°C, for 8 hours to 24 hours, preferably left overnight for 12 hours for complete drying of the fibres. The aforesaid process helps to remove the water-soluble impurities present in the fruiting bodies.
The dried fibres obtained are soaked in ethanol for 18 to 48h hours, preferably 24 hours to partially deacetylate and deproteinize chitinous fibres and to remove organic soluble impurities. The dried fibres are preferably soaked in 70% EtOH.
The fibres obtained from the above process are filtered and dried in hot air oven in a temperature range of 40°C to 80°C, preferably at 50°C, for 8 hours to 24 hours, preferably left overnight for 12 hours to completely evaporate ethanol from the fibres and to obtain dried mushroom fibres from the fruiting body of the mushroom. The fibres obtained have very low density in the range of 0.03 to 0.6 g/cm3 and low elongation of about 7%. The fibres obtained have high tenacity and crystallinity in the range 50 to 65%. The size of the fibres obtained is 1-5mm.
The fibres are mixed with biodegradable polymer to obtain a mixed fibre as described in figure 4. In more preferred embodiment, polyvinyl alcohol (PVA) is used as a biodegradable polymer in the range of 30 to 60 % by weight. In particular, water is used as a solvent to dissolve polymer. The blending of fibres and polymer was done, preferably, in a high shear mechanical mixer for uniform mixing and dispersing in the polymer phase.
In an embodiment of the present invention, other suitable polymers similar to PVAknown in the art can be used while preparing the composite bio leather. The properties of suitable polymers may include but not limited to water solubility to keep overall process green and environmentally friendly; strong binding capacity to hold fibres together with polymer matrix; thermo-plasticity, so that biomaterial could be processed by thermal process during post processing; film forming properties and high flexibility for perform like leather; and biodegradability to minimize harmful environmental effects caused by waste plastics.

To provide the desirable flexibility, specially designed plasticizers formulation is added to the mixed fibre and blended to obtain a blended fibre solution. In a preferred embodiment, the plasticizer formulation is added in the range of 40 to 70 % by weight of biodegradable polymer. In other words, the weight percent of plasticizer is in a range of 40 to 70 % that of the biodegradable polymer’s weight. In a preferred embodiment, plasticizer formulation contains glycerol 30-50 %, propylene glycol 10-20 %, and polyethylene glycol (Mw 200) 10 to 20 %.
In an embodiment of the present invention, the prepared blended fibre solution obtained from the aforesaid process is layered on a metallic tray. The tray is placed in a hot air oven to dry at temperature 50? to 80?, preferably at 60?, for 10 hours to 12 hours. Drying for a prolonged period of time may accelerate the drying process but it may lead to sheet deformation. After drying, the composite sheet is heat pressed to obtain uniform thickness and smoothness.
In an embodiment of the present invention, post drying processing is performed on the composite sheet obtained from the above steps as shown in figure 5. The composite sheet is heat pressed to flatten it which is followed by microthinning, preferably 0.5 mm to 1.0 mm. The composite sheet is further coated on the surface using a surface coating solution. In a preferred embodiment, surface coating solution is prepared by mixing polyvinyl alcohol 8-10 % by wt, glycerol 1 % by wt, colour pigment 0.1-0.5 % by wt in water, for instance, blue, black, brown etc. color pigments, followed by thorough stirring, preferably in a high-speed mechanical stirrer at temperature 50? to 80?, preferably at 50? for 2 hours to 4 hours. The composite sheet is further heat pressed to obtain a final finished material or a bio-composite leather as shown in figure 6.
Example 1
In an embodiment of the present invention the invention can be performed in below manner
Weight of fruiting bodies Weight of fibres extracted from mushroom Biodegrada ble polymer Plasticiser formulation Weight of
composite sheet obtained Thickness of composite sheet
fruiting bodies (….)
250 g 100 g 180 g 90 gm 1950 g/m2 1.8 mm

According to Example 1, 250 g of mushroom fruiting bodies is used to extract fibres. 100 g of fibre is extracted from the mushroom fruiting bodies and soaked in ethanol (100% EtOH) 24 hours after removal of impurities. The obtained fibre is blended with 180 g of polyvinyl alcohol (PVA) and 1800 ml water and 90 g of plasticizer formulation, that is 50% by wt of the biodegradable polymer or PVA, comprising glycerol 30 g, propylene glycol 30 g, and polyethylene glycol (Mw 200) 30 g in a manner disclosed above. After completion of the
method for preparation of the bio-composite leather as described above, the amount of bio-composite leather produced is 1950 g/m2 and the thickness of bio-composite leather sheet is 1.8 mm mm/cm.

Example 2
S. No Key parameters Biodegradable composite sheet ( Sleen lab ) Biodegradable composite sheet ( Sleen lab ) Biodegradable composite sheet ( Sleen lab )
1 Fruiting body fibre and PVA percentage Composite sheet (Fruiting body - 30%; PVA – 70 %) Composite sheet (Fruiting body - 40%; PVA – 60 %) Composite sheet
(Fruiting body - 50%; PVA – 50 %)
2 Breaking strength (N/cm) D1: 83 N/cm D2: 82 N/cm D1: 130 N/cm D2: 113 N/cm D1: 82 N/cm D2: 88 N/cm
3 Elongation (%) 13% 12.80% 12.60%
4 Tensile Strength 9.7 MPa 12.1 MPa 11.7 MPa
5 Bally Flex resistance Severe checked observed @75000 cycles Severe checked observed @ 45000 cycles Severe checked observed @ 46000 cycles
7 Colour fastness (rubbing method) Dry (10 cycle) - Class 4 (slightly changed) Wet (10 cycle) - Class 2-3 (Noticeably changed) Dry (10 cycle) - Class 4 (slightly changed) Wet (10 cycle) - Class 2-0 (Noticeably changed) Dry (10 cycle) - Class 4 (slightly changed) Wet (10 cycle) - Class 2-3 (Noticeably changed)
8 Tongue tear strength D1: 20N D2: 17N D1: 29N D2: 16.4N D1: 21N D2: 25N

In the present invention, biodegradable composite material underwent a comprehensive series of tests at SLEEN testing lab to evaluate their prepration technology, breaking strength (N/cm, elongation (%), tensile Strength, bally flex resistance, colour fastness (rubbing method), tongue tear strength shown in above table. The table compares biodegradable composite material A, biodegradable composite material B, biodegradable composite material C based on the ratio of fruiting body fibre to PVA and performance attributes. Biodegradable composite material A uses composite sheet (30%), breaking strength of D1: 83 N/cm D2: 82 N/cm, elongation of 13%, tensile strength of 9.7 MPa. Under bally flex resistance, severe checking was observed @75000 cycles. For colour fastness rubbing method was used and slight changes were observed at Dry (10 cycle) - Class 4 whereas noticeable changes were observed in Wet (10 cycle) - Class 2-3. Finally, the tongue tear strength of D1: 20N D2: 17N was observed.

Biodegradable composite material B uses composite sheet (40%), breaking strength of D1: 130 N/cm D2: 113 N/cm, elongation of 12.80%, tensile strength of 12.1 MPa. Under bally flex resistance, severe checking was observed @45000 cycles. For colour fastness rubbing method was used and slight changes were observed at Dry (10 cycle) - Class 4 whereas, noticeable changes were seen in Wet (10 cycle) - Class 2-0 indicates noticeably changes. Finally, the tongue tear strength of D1: 29N D2: 16.4N was displayed.

Bio-composite material C uses biodegradable composite sheet (50%), breaking strength D1: 82 N/cm D2: 88 N/cm, elongation of 12.60%, tensile strength of 11.7 MPa. Under bally flex resistance, severe checking was observed @ 46000 cycles. For colour fastness rubbing method was used and slight changes were observed at Dry (10 cycle) - Class 4 whereas, noticeable changes were seen in Wet (10 cycle) - Class 2-3. Finally, the tongue tear strength of D1: 21N D2: 25N was displayed.

Furthermore, according to the method of present invention, the aforementioned desired characteristics such as breaking strength, elongation and tensile strength in the biodegradable composite material are achieved with the use of PVA or any other similar polymer known in the art.

The bio-composite leather obtained has several uses, applications, and advantages in a variety of sectors. Bio-composite leather can be used to create items such as shoes, handbags, wallets, belts, and clothing. The bio-composite leather can be crafted to impart unique textures, colours, and patterns that cater to eco-conscious consumers seeking ethical alternatives to traditional leather products. The bio-composite leather can also be utilised in the production of accessories like watch straps, phone cases, and jewellery, as well as home goods such as upholstery, furniture, and interior decor items. The durability and customizability make it a desirable choice for eco-friendly design projects. The bio-composite leather can also have its application in automotive industry to design interior components like seat covers, steering wheel wraps etc. The bio-composite leather can be utilised in medical and textile industry for wound dressings, surgical implants, and biodegradable textiles. Its breathable and moisture-wicking properties can also benefit the textile industry in creating sustainable and comfortable fabrics.

Source and origin of the fungal strain
The fungal strain described in the present application was isolated from dead tree wood obtained from village Bagdodhi Bangar, Kanpur, Uttar Pradesh, India.
,CLAIMS:We Claim:
1. A method of preparation of biodegradable composite material, the method comprising
a. extraction of fibres of fruiting bodies of Dichomitus sp.;
b. blending with biodegradable polymer to obtain the biodegradable composite material.
2. The method of preparation of biodegradable composite material as claimed in claim 1, wherein the fruiting bodies are selected from the fruiting bodies of fungal strain, Dichomitus sp. deposited under MTCC 25684.
3. The method of preparation of biodegradable composite material as claimed in claim 1, wherein the step a) extraction of fibres of fruiting bodies of Dichomitus sp. comprises the following steps:
a. breaking the fruiting bodies into small pieces;
b. boiling the smaller pieces in water for 20-40 minutes, preferably 30 minutes;
c. grinding the small pieces of fruiting body to obtain ground fibres;
d. filtering and drying the ground fibres at a temperature range of 60°C to 100°C, preferably at 80°C, for 8 hours to 24 hours, preferably 12 hours to obtain dried fibres;
e. soaking the dried fibres in ethanol for 18 hours to 48 hours, preferably 24 hours to partially deacetylate and deproteinize chitineous fibres and remove organic soluble impurities to obtain soaked fibres;
f. filtering and drying the soaked fibres at a temperature range of 40°C to 80°C, preferably at 50°C, for 8 hours to 24 hours, preferably 12 hours to completely evaporate ethanol from the fibres and to obtain dried mushroom fibres from the fruiting body of of Dichomitus sp. mushroom.
4. The method of preparation of biodegradable composite material as claimed in claim 1, wherein the biodegradable polymer is polyvinyl alcohol and is blended in step b) in the range of 30 to 60 % by weight.
5. The method of preparation of biodegradable composite material as claimed in claim 1, wherein in step b) a plasticizer is added to the blend of mushroom fibres and biodegradable polymer.
6. The method of preparation of biodegradable composite material as claimed in claim 5, wherein the plasticizer is in the weight range of 40 to 70% by weight of the polymer and comprises glycerol 30-50 %, propylene glycol 10-20 %, and polyethylene glycol (Mw 200) 10 to 20 % by weight.
7. The method of preparation of biodegradable composite material as claimed in claim 1 or claim 5, wherein the blend of mushroom fibres, biodegradable polymer and plasticizer is layered on trays and dried in a hot air oven at a temperature in the range of from 50 to 80?, preferably 60? to obtain a dried fibre sheet.
8. The method of preparation of biodegradable composite material as claimed in claim 7, wherein the layers have equal thickness ranging between 2-4 mm, preferably 1-2 mm.
9. The method of preparation of biodegradable composite material as claimed in claim 7, wherein the dried fibre sheet or composite sheet obtained is heat pressed, followed by microthinning to preferably 0.5 mm to 1.0 mm.
10. The method of preparation of biodegradable composite material as claimed in claim 8, wherein post microthinning, the dried fibre sheet is coated with surface coating solution comprising polyvinyl alcohol 8-10 % by wt, glycerol 1 % by wt, colour pigment 0.1-0.5 % by wt in water followed by heat pressing of the sheet.
11. The method of preparation of biodegradable composite material as claimed any one of claims 1 or 7, wherein the biodegradable composite material is a bio-composite leather.
12. A biodegradable composite material produced by the method as claimed in any of the preceding claims.