Biocomposites of antimicrobial properties based on renewable polymers and lignocellulosic fibers

Abstract

The present disclosure reveals a biocomposite material based on a biodegradable polymer such as poly(lactic acid) (PLA; 50.00-95.00% w / w), lignocellulose fibers from renewable energy crops (0.10-50.00% w / w), nano-clay (NC) (0.10-20.00% w / w), two or more antimicrobial additives (AMA; 0.10-20.00% w / w), a drying oil like linseed oil (0.05- 6.00% w / w), and optionally, one or more predominantly renewable functional additives selected from the group consisting of flame retardants, plasticizers, stabilizers including antioxidants and UV- stabilizers, slip agents, lubricants including internal and external, biocides, colorants, and fillers. The said composite contains a combination of AMAs based on zinc oxide (ZnO) and milled cork (MC). The biocomposite material according to the present disclosure is used for the manufacturing of sustainable industrial products as a substitute for conventional composite materials made from non-renewable, petrochemical-based polymers.

Description

[0001] BIOCOMPOSITES OF ANTIMICROBIAL PROPERTIES BASED ON RENEWABLE POLYMERS

[0002] AND LIGNOCELLULOSIC FIBERS

[0003] BACKGROUND

[0004] Field

[0005] The present invention discloses the novel biocomposites based on lignocellulosic fibers, renewable polymer, drying oil, and a combination of zinc oxide and cork that exhibit antimicrobial properties, to their production and use.

[0006] Description of the Related Art

[0007] A composite material is a material produced from two or more constituent material which remains separate and distinct within the resulting composite. The latter is typically comprised of one or more polymers usually reinforced with some kind of fibers . In the case that the polymer and fibers are environmentally friendly and renewable, such composite is considered biocomposites. These are an extremely important, relatively novel class of materials that find their widespread use in the industry, see for instance literature references 1 and 2.

[0008] 1) M. Zimniewska, M. Wladyka-Przybylak, J. Mankowski: Chapter 4. Cellulosic Bast Fibers, Their Structure and Properties Suitable for Composite Application, p. 97-119; in S. Kalia et . Al. (Eds. ) : Cellulose Fibres: Bio- and Nano-Polymer Composites, Springer- Verlag Berlin Heidelberg (2011) ; and

[0009] 2) A. K. Trivedi, M. K. Gupta, H. Singh: PLA based biocomposites for sustainable products: A review, Adv. Ind. Eng. Polym. Res. 6 (2023) 382-395. Among renewable biopolymers, poly(lactic acid) (PLA) , polyhydroxybutyrate (P3HB) , and copolymers of polyhydroxybutyrate and 3-hydroxyvalerate or poly ( 3-hydroxybutyrate-co-3-hydroxyvalerate ) (PHBV) have been employed in biocomposite materials, see, e.g., literature reference 3 :

[0010] 3) N. Delpouve, H. Fara j , C. Demarest, E. Dontzoff, M.-R. Garda, L. Delbreilh, B. Berton, E. Dargent : Water-Induced Breaking of Interfacial Cohesiveness in a Poly(lactic acid) / Miscanthus Fibers Biocomposite, Polymers 13 (2021) 2285.

[0011] Natural fibers that serve for biocomposite reinforcement can be various lignocellulosic fibers that can be manufactured from different energy crops including miscanthus (Miscanthus x giganteus) , giant cane (Arundo donax L. ) , Spanish broom (Spartium junceum L . ) , flax (Linum usitatissimum L. ) , and similar plants, see for instance literature references 3-5 :

[0012] 4) V. Fiore, L. Botta, R. Scaffaro, A. Valenza, A. Pirrotta: PLA based biocomposites reinforced with Arundo donax fillers, Compos. Sol . Technol. 105 (2014) 110-117; and

[0013] 5) Z. Kovacevic, S. Bischof, E. Vujasinovic, M. Fan: The influence of pre-treatment of Spartium junceum L. fibres on the structure and mechanical properties of PLA biocomposites, Arab. J. Chem. 12 (2019) 449-463.

[0014] Composite materials are often modified with different additives that improve their certain particular technological properties such as thermal properties, flammability, mechanical properties like tensile strength, flexural strength, tensile modulus, antimicrobial properties, oxidative stability, hydrolytic stability, hydrophobicity, etc. Some of the typical environmentally friendly functional additives that have been used in biocomposite compositions are montmorillonite clay (MMT) , zinc oxide (ZnO) , and linseed oil (LO) , see, e.g., literature references 6-8 : 6) R. Ramesh, B. Durga Prasad, K. L. Narayana: Influence of Montmorillonite Clay Content on Thermal, Mechanical, Water Absorption and Biodegradability Properties of Treated Kenaf Fiber / PLA-Hybrid Biocomposites, Silicon 13 (2021) 109-118;

[0015] 7) A. Marra, C. Silvestre, D. Duraccio, S. Cimmino : Polylactic acid / zinc oxide biocomposite films for food packaging application, Int. J. Biol. Macromol. 88 (2016) 254-262; and

[0016] 8) J. Lazko, B. Dupre, R. M. Dheilly, M. Queneudec: Biocomposites based on flax fibres and linseed oil, Ind. Crops Prod. 33 (2011) 317-324.

[0017] Cork particles obtained from the cork oak (Quercus suber L. ) have been recognized as a potent renewable starting material for manufacturing various engineered materials contributing different valuable properties of the resulting products including thermic, acoustic, high resistance to abrasion, non-toxicity, hypoallergenicity, elasticity, compressibility, viscoelasticity, non-permeability to gases and liquids, recyclability, and biodegradability. Cork consists of suberin (33-50%) , lignin (13-29%) , polysaccharides (6-25%) , and extractives (8.5-24%) and has also been used as an additive for the manufacturing of biocomposites, see, e.g., literature reference 9:

[0018] 9) E. M. Fernandes, V. M. Correlo, J. F. Mano, R. L. Reis: Cork- polymer biocomposites: Mechanical, structural and thermal properties, Mater. Des. 82 (2015) 282-289.

[0019] The technical problem that is solved by the subject disclosure is related to the disadvantages of current composite materials based on nonrenewable petrochemical resources, often from highly toxic chemicals, e.g. , bisphenol A or epichlorohydrin, as well as known biocomposites sensitive to microbial decay that could be eventually preserved with certain non-toxic and renewable antimicrobial additives (AMA) .

[0020] According to our best knowledge, said complex technical problem has not been solved yet by a composite material made from a biodegradable polymer such as poly(lactic acid) (PLA) and lignocellulosic fibers, with the addition of nano-clay (NC) , drying oil (DO) , and special environmentally friendly AMA based on a combination of zinc oxide (ZnO) and micronized cork (MC) as disclosed in section Detailed Description.

[0021] SUMMARY

[0022] The present invention discloses a novel biocomposite material comprising :

[0023] (i) a biodegradable polymer of a glass transition temperature (Tg) 40-180 °C, 50.00-95.00% w / w,

[0024] (ii) lignocellulose fibers from renewable energy crops, where a minimum of 90% are characterized by their length within 0.2-200 mm, and diameter within 0.001-0.2 mm, 0.10-50.00% w / w,

[0025] (iii) nano-clay (NC) as a flame retardant, which is minimally 90% within the range of particle size of not more than 20 pm, 0.10- 20.00% w / w,

[0026] (iv) antimicrobial additives (AMA) , 0.10-20.00% w / w,

[0027] (v) optionally, one or more additional functional additives from predominantly renewable resources selected from the group consisting of flame retardants, plasticizers, stabilizers including antioxidants and UV-stabilizers , slip agents, lubricants including internal and external, biocides, colorants, and fillers, 0.00-3.00% w / w, where the said composite additionally contains :

[0028] (vi) a drying oil (DO) , 0.05-6.00% w / w, and where the antimicrobial additive (AMA) is a combination of zinc oxide (ZnO) where at least 90% of particle sizes are within the range 0.02- 0.25 mm, and milled cork (MC) where at least 90% of particle sizes are within the range of 0.02-0.60 mm.

[0029] In a preferred embodiment of this invention, the biodegradable polymer that is used in the said biocomposite material is poly (lactic acid) (PLA) . The lignocellulose fibers that are employed in the subject composite material are made by sodium hydroxide (NaOH) -based pulping of the plant material selected from the group consisting of Spanish broom (Spartium junceum L. ) , Virginia mallow [Sida hermaphrodita (L. ) Rusby] , or mixtures of these plant materials.

[0030] In another preferred embodiment of the subject disclosure, the nanoclay (NC) ingredient is selected from the group consisting of montmorillonite [MMT, (Na, Ca) 0.33 (Al, Mg) 2Si40io (OH) 2 • nLRO] , bentonite, kaolin [A12Si20s (OH) 4] , palygorskite [ (Mg, Al ) 2Si40io (OH) • 4H2O] , micas such as muscovite [KAI2 (AlSisOio) (F,OH)2] , surface modified minerals of said group with 10-30% w / w octadecylamine, 10-30% w / w trimethylstearyl ammonium, or 10-45% w / w dimethyl dialkyl (C14-C18 ) amine, or mixtures of these substances. Preferably, the nano-clay (NC) ingredient is montmorillonite (MMT) .

[0031] In a preferred embodiment of the present invention, the weight percentage of ingredients (i)-(vi) are as follows:

[0032] (i) 50.00-80.00% w / w,

[0033] (ii) 5.00-40.00% w / w,

[0034] (iii) 1.00-10.00% w / w,

[0035] (iv) 1.00-10.00% w / w, of which 1.00-5.00% w / w is zinc oxide (ZnO) and 1.00-5.00% is milled cork (MC) ,

[0036] (v) 0.10-1.00% w / w, and

[0037] (vi) 0.25-2.00% w / w.

[0038] Concerning the optional use of fully or predominantly renewable functional additives, these are selected from the groups comprising: flame retardants, plasticizers, stabilizers, slip agents, lubricants, biocides, colorants, fillers, or mixtures of these substances.

[0039] The biocomposite material according to the subject disclosure also contains the drying oil (DO) that is selected from the groups comprising : (a) raw, refined, stand, or boiled oils with an iodine number higher than 130, such as linseed oil (LO) , tung oil, poppy seed oil, perilla oil, or walnut oil,

[0040] (b) stand oils made from semi-drying oils such as sunflower oil, soybean oil, corn oil, cottonseed oil, sesame oil, or grape seed oil, and

[0041] (c) boiled oils made from: semi-drying oils such as sunflower oil, soybean oil, corn oil, cottonseed oil, sesame oil, or grape seed oil, and a siccative such as manganese, zirconium, iron, or zinc naphthenates , or mixtures of these substances, without or with the additional, catalytic amount, from 0.01-2.00% w / w, of said metallic siccative calculated to the weight of starting oil. In a preferred embodiment of this invention, the drying oil (DO) is linseed oil (LO) .

[0042] The process for preparing the biocomposite material according to the present invention includes the following manufacturing steps :

[0043] A. drying of biodegradable polymer at 100-105 °C for 0.5-24 h,

[0044] B. lignocellulose fibers are subjected to carding and drying at 100- 105 °C for 0.5-24 h,

[0045] C. nano-clay (NC) , antimicrobial additives (AMA) , and other optional additives are dried at 100-105 °C for 0.5-24 h and then mixed with drying oil (DO) by kneading at room temperature for 15-30 minutes, yielding a coating mixture for the lignocellulose fibers,

[0046] D. a coating of the dried lignocellulose fibers from Step B with the coating mixture from Step C,

[0047] E. the dried biodegradable polymer from Step A is placed into the molds and subjected to melting at 180-200 °C for 5-15 minutes yielding thin sheets of 2-4 mm thickness, which are allowed to cool to 20-30 °C,

[0048] F. the coated lignocellulose fibers from Step D are placed on the first thin sheet of the polymer obtained in Step E taking care that the coated lignocellulose fibers are oriented in one direction in the case of unidirectional composites, or in several directions in the case of multi-directional composites, and G. the thin polymer sheet with placed coated lignocellulose fibers from Step F is covered with the second thin polymeric sheet from Step E, and thus obtained sandwich-type structure is subjected to pressing at 185-195 °C for 160-200 seconds, at 25-40 kN with degassing for 30-60 seconds, yielding a sheet of the composite material .

[0049] The composite material according to the subject disclosure is used for manufacturing industrial products as a substitute for conventional composite materials that are made from petrochemical-based polymers.

[0050] Particularly, the biocomposite material according to the present invention is used for manufacturing different industrial products in the automotive industry: interior components such as door panels, dashboards, and trunk liners; construction: wall-, roofing-, or insulation panels; packaging industry: various packaging products; consumer goods: furniture, casings for various electronic products, sports goods; medical devices: orthopedic implants, dental materials; agriculture: biodegradable mulch films, plant pots, as well as in aerospace industry: various lightweight components and parts.

[0051] DETAILED DESCRIPTION

[0052] The subject disclosure reveals a biocomposite material comprising:

[0053] (i) a biodegradable polymer of a glass transition temperature (Tg) 40-180 °C, 50.00-95.00% w / w,

[0054] (ii) lignocellulose fibers from renewable energy crops, where a minimum of 90% are characterized by their length within 0.2-200 mm, and diameter within 0.001-0.2 mm, 0.10-50.00% w / w,

[0055] (iii) nano-clay (NC) as a flame retardant, which is minimally 90% within the range of particle size of not more than 20 pm, 0.10- 20.00% w / w,

[0056] (iv) antimicrobial additives (AMA) , 0.10-20.00% w / w,

[0057] (v) optionally, one or more additional functional additives from fully or predominantly renewable resources selected from the group consisting of flame retardants, plasticizers, stabilizers including antioxidants and UV-stabilizers , slip agents, lubricants including internal and external, biocides, colorants, and fillers, 0.00-3.00% w / w, where the said composite additionally contains : (vi) a drying oil (DO) , 0.05-6.00% w / w, and where the antimicrobial additive (AMA) is a combination of zinc oxide (ZnO) where at least 90% of particle sizes are within the range 0.02- 0.25 mm, and milled cork (MC) where at least 90% of particle sizes are within the range of 0.02-0.60 mm.

[0058] In a preferred embodiment of this invention, the biodegradable polymer that is used in the said biocomposite material is poly(lactic acid) (PLA) .

[0059] The lignocellulose fibers that are employed in the subject composite material are made by sodium hydroxide (NaOH) -based pulping of the plant material selected from the group consisting of Spanish broom (Spartium junceum L. ) , Virginia mallow [Sida hermaphrodita (L. ) Rusby] , or mixtures of these plant materials of length 5-30 mm and diameter or width 0.1-5 mm. The plant feedstock is subjected to cooking in an aqueous sodium hydroxide (NaOH) solution of 1.0-5.0% w / w concentration, at the weight ratio: plant feedstock NaOH solution (1.0-5.0% w / w) 1 : 6-20, w / w, at 95-100 °C for 1-3 h. Thus obtained lignocellulose pulp is separated by filtration and pressing, yielding the waste filtrate, known as a black liquor, and crude, wet, lignocellulose pulp, that is washed several times with demineralized water until the pH value of the resulting filtrate is close to 7. Then, obtained lignocellulose pulp is subjected to drying at 100-105 °C furnishing the lignocellulose fibers that can be employed for the preparation of the subject composite material . These types of NaOH-based pulping processes can be found in various literature references, e.g., see literature references 5.

[0060] The typical procedure for preparing lignocellulose fibers suitable for use in the subject biocomposite material composition is disclosed in Example 2.

[0061] In another preferred embodiment of the subject disclosure, the nanoclay (NC) ingredient is selected from the group consisting of montmorillonite [MMT, (Na, Ca) 0.33 (Al, Mg) 2Si40io (OH) 2 • nfhO] , bentonite, kaolin [A12Si20s (OH) 4] , palygorskite [ (Mg, Al ) 2Si40io (OH) • 4H2O] , micas such as muscovite [KAI2 (AlSisOio) (F,OH)2] , surface modified minerals of said group with 10-30% w / w octadecylamine, 10-30% w / w trimethylstearyl ammonium, or 10-45% w / w dimethyl dialkyl (C14-C18 ) amine, or mixtures of these substances. Preferably, the nano-clay (NC) ingredient is montmorillonite (MMT) .

[0062] Nevertheless, in another preferred embodiment of the present invention, the weight percentage of ingredients (i)-(vi) are as follows:

[0063] (i) 50.00-80.00% w / w,

[0064] (ii) 5.00-40.00% w / w,

[0065] (iii) 1.00-10.00% w / w,

[0066] (iv) 1.00-10.00% w / w, of which 1.00-5.00% w / w is zinc oxide (ZnO) and 1.00-5.00% is milled cork (MC) ,

[0067] (v) 0.10-1.00% w / w, and

[0068] (vi) 0.25-2.00% w / w.

[0069] Concerning the optional use of fully or predominantly renewable functional additives, these are selected from the groups comprising: flame retardants: aluminium hydroxide [Al (OH) 3g, hydromagnesite [Mgs (CO3 ) 4 (OH) 2 • 4H2O] , zinc borate [Zns (603)2] , or mixtures of these substances , plasticizers: di ( 2-ethylhexyl ) adipate (DEHA) , dioctyl adipate (DOA) , diheptyl adipate (DHA) , heptyl adipate (HAD) , heptyl octyl adipate (HOA) , or mixtures of these substances, stabilizers: butylated hydroxytoluene (BHT) , butylated hydroxyanisole (BHA) , pentaerythritol tetrakis [3- (3, 5-di-tert- butyl ) -4 -hydroxyphenyl ) propionate] , octadecyl -3- ( 3 , 5 -di- ter t- butyl-4-hydroxypheny) propionate, or mixtures of these substances, slip agents: calcium stearate, zinc stearate, erucamide, oleamide, stearamide, carnauba wax, candelilla wax, or mixtures of these substances , lubricants: C14-18 fatty alcohols like stearyl alcohol, metallic soaps like calcium or zinc stearate, higher fatty acids like palmitic acid, amide waxes such as N, N' -ethylene distearamide, glycerol esters with higher saturated fatty acids like glyceryl monostearate, glycerol esters of saturated hydroxy-derived fatty acids such as hydrogenated castor oil, glycerol partial esters of saturated fatty acids like mixtures of glyceryl monostearate and glyceryl dipalmitate, hydrocarbon waxes such as paraffin, polyethylene wax, or mixtures of these substances, biocides: 2-phenylphenol, chloroxylenol, 4-chloro-m-cresol , chlorhexidine and its salts, benzalkonium chloride, cetylpyridinium chloride, didecyldimethylammonium chloride, benzethonium chloride, benzoic acid, or mixtures of these substances , colorants: natural or synthetic mineral pigments like yellow iron oxide (Fe2O3-H2O) , red iron oxide (Fe2O3) , or black iron oxide (FesCA) , cobalt blue or cobalt (II) aluminate (C0AI2O4) , ultramarine violet, cobalt violet [Co3(P04)2] , manganese violet or ammonium manganese ( II ) pyrophosphate (NH4MnP20v) , chrome green (C^Os) , viridian or hydrated chromium ( III ) oxide (C^Os'PhO) , cobalt green or zinc green (CoZn02) , green earth or Verona green

[0070] [K [ (Al, Fe3+) , ( Fe2+,Mg] (AlSis, Si4 ) O10 (OH) 2] , malachite or basic copper carbonate [CU2 (OH) 2CO3] , Prussian blue or iron(III) hexacyanof errate ( III ) { Fe4 [Fe (CN) e] 3 } , ultramarine, ultramarine violet, carbon black, vegetable black, manganese black or manganese dioxide (Mn02) , titanium white or titanium dioxide (Ti02) , lithopone (BaSO4-ZnS) , bronze powder, phthalocyanine blue BN pigments, phthalocyanine green G pigments, or quinacridone pigments, or mixtures of these pigments, soluble organic dies such as azo dyes or lake pigments derived thereof, or mixtures of these substances, and fillers: natural milled or synthetic, precipitated calcium carbonate (CaCOs) , talc [MgsSi^io (OH) 2] , natural milled or synthetic precipitated barium sulfate (BaSO4) , or mixtures of these substances .

[0071] The biocomposite material according to the subject disclosure also contains the drying oil (DO) that is selected from the groups comprising :

[0072] (a) raw, refined, stand, or boiled oils with an iodine number higher than 130, such as linseed oil (LO) , tung oil, poppy seed oil, perilla oil, or walnut oil,

[0073] (b) stand oils made from semi-drying oils such as sunflower oil, soybean oil, corn oil, cottonseed oil, sesame oil, or grape seed oil, and

[0074] (c) boiled oils made from: semi-drying oils such as sunflower oil, soybean oil, corn oil, cottonseed oil, sesame oil, or grape seed oil, and a siccative such as manganese, zirconium, iron, or zinc naphthenates , or mixtures of these substances, without or with the additional, catalytic amount, from 0.01-2.00% w / w, of said metallic siccative calculated to the weight of starting oil.

[0075] In a preferred embodiment of this invention, the drying oil (DO) is linseed oil (LO) .

[0076] A process for preparing the biocomposite material according to the present invention

[0077] The process for preparing the biocomposite material according to the subject disclosure includes the following manufacturing steps:

[0078] A. drying of biodegradable polymer at 100-105 °C for 0.5-24 h,

[0079] B. lignocellulose fibers are subjected to carding and drying at 100- 105 °C for 0.5-24 h, C . nano-clay (NC ) , antimicrobial additives (AMA) , and other optional additives are dried at 100-105 ° C for 0 . 5 -24 h and then mixed with drying oil ( DO ) by kneading at room temperature for 15 -30 minutes , yielding a coating mixture for the lignocellulose fibers ,

[0080] D . a coating of the dried lignocellulose fibers from Step B with the coating mixture from Step C,

[0081] E . the dried biodegradable polymer from Step A is placed into the molds and subj ected to melting at 180-200 ° C for 5-15 minutes yielding thin sheets of 2 -4 mm thickness , which are allowed to cool to 20-30 ° C,

[0082] F . the coated lignocellulose fibers from Step D are placed on the first thin sheet of the polymer obtained in Step E taking care that the coated lignocellulose fibers are oriented in one direction in the case of unidirectional composites , or in several directions in the case of multi-directional composites , and

[0083] G . the thin polymer sheet with placed coated lignocellulose fibers from Step F is covered with the second thin polymeric sheet from Step E , and thus obtained sandwich-type structure is subj ected to pressing at 185-195 ° C for 160-200 seconds , at 25 -40 kN with degassing for 30- 60 seconds , yielding a sheet of the composite material .

[0084] The typical experimental procedures for preparing the biocomposite material according to the subj ect invention are disclosed in Examples 1 , 3 , and 4 .

[0085] Use of the biocomposite material according to the subj ect disclosure

[0086] The composite material according to the subj ect disclosure is used for manufacturing different industrial products as a substitute for conventional composite materials that are made from petrochemical-based polymers , which enable improved sustainability, biodegradability, lower environmental impact , enhanced biocompatibility, lighter weight , and thus improved fuel efficiency in the automotive industry and similar applications , improved insulation, cost-efficiency, design flexibility, without or less toxic leachables, and thus improved health and safety profile .

[0087] Particularly, the biocomposite material according to the subject disclosure is used for manufacturing different industrial products in the : automotive industry: interior components such as door panels, dashboards, trunk liners, construction: wall-, roofing-, or insulation panels, packaging industry: various packaging products, consumer goods: furniture, casings for various electronic products, sport goods, medical devices: orthopedic implants, dental materials, agriculture: biodegradable mulch films, plant pots, aerospace industry: various lightweight components and parts.

[0088] Experimental Part

[0089] General information

[0090] The term "room temperature" (r.t. ) refers to a temperature interval of 20-25 °C. The composition of composite materials according to the present invention is expressed in weight percentages (% w / w) of the corresponding ingredients.

[0091] Example 1. Preparation of a composite material according to the present disclosure

[0092] Composition (for 30.00 g of the composite material) :

[0093] (i) 50.00% w / w (15.00 g) biodegradable polymer, poly(lactic acid) (PLA) of type Ingeo Biopolymer 6201D, with a glass transition temperature (Tg) 55-60 °C,a

[0094] (ii) 46.00% w / w (13.80 g) lignocellulose fibers obtained from Spanish broom (Spartium junceum L. ) , of which a minimum of 90% are characterized by their length within 10-200 mm, and diameter within 0.001-0.2 mm,13

[0095] (iii) 1.00% w / w (0.30 g) nano-clay (NC) of type Sigma-Aldrich nanomer 1.31PS&, of a particle size not more than 20 pm,c

[0096] (iv) antimicrobial additives (AMA) :

[0097] 1.00% w / w (0.30 g) zinc oxide,d

[0098] 1.00% w / w (0.30 g) milled cork (MC) ,e

[0099] (v) no optional functional additives were used in this experiment, and,

[0100] (vi) 1.00% w / w (0.30 g) linseed oil (LO) as a drying oil (DO) .f

[0101] Total: 100.00% w / w (30.00 g)

[0102] Procedure :

[0103] A. A sample of PLA (i) granules was dried in a laboratory drying oven at 100-105 °C for 24 h,

[0104] B. lignocellulose fibers (ii) were subjected to carding and drying at 100-105 °C for 24 h,

[0105] C. nano-clay (iii) and AMA ZnO + MC (iv) were dried in a laboratory drying oven at 100-105 °C for 24 h and then mixed with linseed oil (vi) as a drying oil by kneading at room temperature for 15 minutes, yielding a coating mixture for the lignocellulose fibers,

[0106] D. then the dried lignocellulose fibers from Step B were coated with the coating mixture from Step C,

[0107] E. the dried PLA (i) granules from Step A were placed into the molds and subjected to melting at 180-200 °C for 5 minutes yielding thin sheets of dimensions (length x width x thickness) = 80 x 80 x 3 mm, which were allowed to cool to r.t. ,

[0108] F. the coated lignocellulose fibers from Step D were placed on the first thin sheet of the polymer obtained in Step E taking care that the coated lignocellulose fibers are oriented in one direction,

[0109] G. the thin polymer sheet with placed coated lignocellulose fibers from Step F was covered with the second thin polymeric sheet from Step E, and thus obtained sandwich-type structure was subjected to pressing at 190 °C for 180 seconds, at 30 kN with degassing for 30 seconds , yielding a sheet of composite material according to the present disclosure .

[0110] Starting materials :aProduct of company NatureWorks LLC (USA) ;13Product of Example 2;cProduct of company Sigma-Aldrich (USA) ;dProduct of company Carlo Erba S.r.l, Italy;eMC was prepared by the treatment of cork by a cryo-milling, followed by sieving through the 30-mesh sieve, and then vibrated on the 625-mesh sieve. The fraction of MC that passed the 30-mesh sieve and retained on the 625-mesh sieve was used for the preparation of the composite material according to the present disclosure;fProduct of company Iskra Zelina d.o.o. , Croatia.

[0111] Example 2. Preparation of the lignocellulose fibers suitable for the preparation of the composite material according to the present invention

[0112] The dried plant material of the Spanish broom (Spartium junceum L. ) was chopped into small particles of 5-30 mm in length using scissors. The dimension of the material was within the specification of particles length 5-30 mm and diameter or width 0.1-5 mm.

[0113] Chopper Spanish broom material (100.00 g) was suspended in a previously prepared 3.00% w / w solution of sodium hydroxide (NaOH; 24.00 g) in demineralized water (800 mL) . Thus, obtained suspension was stirred with an overhead stirring unit equipped with an anchor-type stirrer at 200-250 o / min at 95-100 °C for 2 h. Then, the suspension was filtered through a Buchner funnel yielding a cooked lignocellulose pulp and a filtrate (so-called "black liquor") which was discarded. Thus, obtained lignocellulose pulp was resuspended in demineralized water (800 mL) and washed at 60-65 °C with vigorous stirring at 200-250 o / min for 15 minutes, and then separated by filtration. This washing procedure was repeated twice, giving the last (third) filtrate of pH value near 7. The product of this procedure was in the form of a wet pale brown lignocellulose pulp of approximately 25-35% w / w dry matter.

[0114] This product was dried in a laboratory oven at 100-105 °C for 2-3 h, yielding a yellowish-to-pale brownish dried lignocellulose fiber (67.50 g; 67.5% chemical yield) of a specification where a minimum of 90% are characterized by their length within 0.2-200 mm and diameter within 0.001-0.2 mm.

[0115] The same procedure can be used for the plant material of Virginia mallow [Sida hermaphrodita (L. ) Rusby] or to the mixtures of said plant and Spanish broom plant materials.

[0116] Example 3. Preparation of a composite material according to the present disclosure

[0117] Composition (for 30.00 g of the composite material) :

[0118] (i) 60.00% w / w (18.00 g) biodegradable polymer, poly(lactic acid) (PLA) of type Ingeo Biopolymer 6201D, with a glass transition temperature (Tg) 55-60 °C,a

[0119] (ii) 28.00% w / w (8.40 g) lignocellulose fibers obtained from Virginia mallow [Sida hermaphrodita (L. ) Rusby] , of which a minimum of 90% are characterized by their length within 10-200 mm, and diameter within 0.001-0.2 mm,13

[0120] (iii) 5.00% w / w (1.50 g) nano-clay (NC) of type Sigma-Aldrich nanomer 1.31PS&, of a particle size not more than 20 pm,c

[0121] (iv) antimicrobial additives (AMA) :

[0122] 3.00% w / w (0.90 g) zinc oxide,d

[0123] 2.00% w / w (0.60 g) milled cork (MC) ,e

[0124] (v) no optional functional additives were used in this experiment, and,

[0125] (vi) 2.00% w / w (0.60 g) linseed oil (LO) as a drying oil (DO) .f

[0126] Total: 100.00% w / w (30.00 g)

[0127] Procedure :

[0128] A. A sample of PLA (i) granules was dried in a laboratory drying oven at 100-105 °C for 2 h,

[0129] B. lignocellulose fibers (ii) were subjected to carding and drying at 100-105 °C for 2 h, C. nano-clay (iii) and AMA ZnO + MC (iv) were dried in a laboratory drying oven at 100-105 °C for 2 h and mixed with linseed oil (vi) as a drying oil by kneading at room temperature for 15 minutes, yielding a coating mixture for the lignocellulose fibers,

[0130] D. then the dried lignocellulose fibers from Step B were coated with the coating mixture from Step C,

[0131] E. the dried PLA (i) granules from Step A were placed into the molds and subjected to melting at 180-200 °C for 5 minutes yielding thin sheets of dimensions (length x width x thickness) = 80 x 80 x 3 mm, which were allowed to cool to r.t. ,

[0132] F. the coated lignocellulose fibers from Step D were placed on the first thin sheet of the polymer obtained in Step E taking care that the coated lignocellulose fibers are oriented in one direction,

[0133] G. the thin polymer sheet with placed coated lignocellulose fibers from Step F was covered with the second thin polymeric sheet from Step E, and thus obtained sandwich-type structure was subjected to pressing at 195 °C for 200 seconds, at 40 kN with degassing for 30 seconds , yielding a sheet of composite material according to the present invention .

[0134] Starting materials :aProduct of company NatureWorks LLC (USA) ;13Product like the one from Example 2;cProduct of company Sigma-Aldrich (USA) ;dProduct of company Carlo Erba S.r.l, Italy;eMC was prepared by the treatment of cork by a cryo-milling, followed by sieving through the 30-mesh sieve, and then vibrated on the 625-mesh sieve. The fraction of MC that passed the 30-mesh sieve and retained on the 625-mesh sieve was used for the preparation of the composite material according to the present disclosure;fProduct of company Iskra Zelina d.o.o. , Croatia.

[0135] Example 4. Preparation of a composite material according to the present disclosure

[0136] Composition (for 30.00 g of the composite material) : (i) 63.79% w / w (19.14 g) biodegradable polymer, poly(lactic acid) (PLA) of type Ingeo Biopolymer 6202D, with a glass transition temperature (Tg) 55-60 °C,a

[0137] (ii) 15.00% w / w (4.50 g) a mixture of lignocellulose fibers obtained from Spanish broom (Spartium junceum L. ) (50%) and Virginia fanpetals [Sida hermaphrodita (L. ) Rusby] (50%) , of which a minimum of 90% are characterized by their length within 10-200 mm, and diameter within 0.001-0.2 mm,13

[0138] (iii) 6.00% w / w (1.80 g) nano-clay (NC) of type Sigma-Aldrich nanomer 1.31PS&, of a particle size not more than 20 pm,c

[0139] (iv) microbiostatic additives (MBA) :

[0140] 2.00% w / w (0.60 g) zinc oxide,d

[0141] 4.00% w / w (1.20 g) milled cork (MC) ,e

[0142] (v) functional additives:

[0143] 5.00% w / w (1.50 g) plasticizer: type Plastomoll DOA, a mixture of di ( 2-ethylhexyl ) adipate (DEHA) and dioctyl adipate (DOA) ,f

[0144] 0.01% w / w (0.003 g; 3 mg) antioxidant / stabilizer : BHT,g0.20% w / w (0.06 g; 60 mg) slip agent: zinc stearate of type Struktol Zinc stearate,11

[0145] 1.00% w / w (0.30 g) colorant: red iron oxide of type Bayferrox 130,1and,

[0146] (vi) 3.00% w / w (0.90 g) boiled linseed oil (LO) of type "Firnis" as a drying oil (DO) J

[0147] Total: 100.00% w / w (30.00 g)

[0148] Procedure :

[0149] A. A sample of PLA (i) granules was dried in a laboratory drying oven at 100-105 °C for 1 h,

[0150] B. lignocellulose fibers (ii) were subjected to carding and drying at 100-105 °C for 1 h,

[0151] C. nano-clay (iii) and MBA ZnO + MC (iv) were dried in a laboratory drying oven at 100-105 °C for 1 h and mixed with linseed oil (vi) as a drying oil, and the rest of said functional additives (v) by kneading at room temperature for 15 minutes , yielding a coating mixture for the lignocellulose fibers ,

[0152] D . then the dried lignocellulose fibers from Step B were coated with the coating mixture from Step C,

[0153] E . the dried PLA ( i ) granules from Step A were placed into the molds and subj ected to melting at 180-200 ° C for 5 minutes yielding thin sheets of dimensions ( length x width x thickness ) = 80 x 80 x 3 mm, which were allowed to cool to 40-50 ° C ,

[0154] F . the coated lignocellulose fibers from Step D were placed on the first thin sheet of the polymer obtained in Step E taking care that the first half of coated lignocellulose fibers are oriented in one direction, while the second half of coated lignocellulose fibers are positioned across the first direction,

[0155] G . the thin polymer sheet with placed coated lignocellulose fibers from Step F was covered with the second thin polymeric sheet from Step E , and thus obtained sandwich-type structure was subj ected to pressing at 190 ° C for 200 seconds , at 35 kN with degassing for 30 seconds , yielding a red-colored sheet of composite material according to the present disclosure .

[0156] Starting materials :aProduct of company NatureWorks LLC (USA) ;13Product like the one from Example 2 ;cProduct of company Sigma-Aldrich (USA) ;dProduct of company Carlo Erba S . r . l , Italy;eMC was prepared by the treatment of cork by a cryo-milling, followed by sieving through the 30-mesh sieve , and then vibrated on the 625-mesh sieve . The fraction of MC that passed the 30-mesh sieve and retained on the 625 -mesh sieve was used for the preparation of the composite material according to the present disclosure ;fProduct of company BASF AG, Germany;gProduct of company Merck KGaA, Germany;hProduct of Struktol Company of America LLC (USA) ;1Product of company Lanxess Deutschland GmbH, Germany;gProduct of company Iskra Zelina d . o . o . , Croatia .

[0157] INDUSTRIAL APPLICABILITY The present invention discloses a novel composition for manufacturing renewable biocomposites with antimicrobial properties . The industrial applicability of the present disclosure is thus obvious .

[0158] ABBREVIATIONS

[0159] AMA = antimicrobial additive

[0160] BHA = butylated hydroxyanisole , a mixture of 2 - tert-butyl-4- methoxyphenol and 3- tert-butyl-4 -methoxyphenol

[0161] BHT = butylated hydroxytoluene , 2 , 6-di- tert-butyl-4-methylphenol

[0162] DEHA = di ( 2 -ethylhexyl ) adipate

[0163] DHA = diheptyl adipate

[0164] DO = drying oil

[0165] DOA = dioctyl adipate

[0166] HAD = heptyl adipate

[0167] HOA = heptyl octyl adipate

[0168] LO = linseed oil

[0169] MC = milled cork

[0170] MMT = montmorillonite

[0171] NC = nano-clay

[0172] PHBV = poly ( 3-hydroxybutyrate-co-3-hydroxyvalerate )

[0173] P3HB = poly ( 3-hydroxybutyrate )

[0174] PLA = poly ( lactic acid )

[0175] Tg = glass transition temperature

Claims

CLAIMS1. A biocomposite material comprising:(i) a biodegradable polymer of a glass transition temperature <Tg> 40-180 °C, 50.00-95.00% w / w,(ii) lignocellulose fibers from renewable energy crops, where a minimum of 90% are characterized by their length within 0.2- 200 mm, and diameter within 0.001-0.2 mm, 0.10-50.00% w / w,(iii) nano-clay <NC> as a flame retardant, which is minimally 90% within the range of particle size of not more than 20 pm, 0.10-20.00% w / w,(iv) antimicrobial additives <AMA>, 0.10-20.00% w / w,(v) optionally, one or more additional functional additives from predominantly renewable resources selected from the group consisting of flame retardants, plasticizers, stabilizers including antioxidants and UV-stabilizers , slip agents, lubricants including internal and external, biocides, colorants, and fillers, 0.00-3.00% w / w, where the said composite additionally contains :(vi) a drying oil <DO>, 0.05-6.00% w / w, and where the antimicrobial additive <AMA> is a combination of zinc oxide <ZnO> where at least 90% of particle sizes are within the range 0.02-0.25 mm, and milled cork <MC> where at least 90% of particle sizes are within the range of 0.02-0.60 mm.

2. The biocomposite material according to claim 1, wherein the biodegradable polymer is poly (lactic acid) <PLA>.

3. The biocomposite material according to any of the previous claims, wherein the lignocellulose fibers made by sodium hydroxide <NaOH>- based pulping of the plant material selected from the group consisting of Spanish broom <Spartium junceum L>, Virginia mallow <Sida hermaphrodita <L> Rusby>, or mixtures of these plant materials .

4. The biocomposite material according to any of the previous claims, wherein the nano-clay <NC> ingredient is selected from the group consisting of montmorillonite <MMT,(Na, Ca) 0.33 (Al,Mg) 2Si40io (OH) 2 • nH20>, bentonite, kaolin< 12Si20s (OH) 4>, palygorskite < (Mg, Al) 2Si40io (OH) • 4H2O>, micas such as muscovite <KA12 (AlSisOio) (F,OH)2>, surface modified minerals of said group with 10-30% w / w octadecylamine, 10-30% w / w trimethylstearyl ammonium, or 10-45% w / w dimethyl dialkyl <C14- C18< amine, or mixtures of these substances.

5. The biosite material according to claim 4, wherein the nanoclay <NC>montmorillonite <MMT(Na,Ca)c.33 (Al, Mg)2Si4Oio (OH)2-nH2O>.

6. The biocomposite material according to any of the previous claims, wherein the preferable weight percentage of ingredients (i) -(vi) are as follows :(i) 50.00-80.00% w / w,(ii) 5.00-40.00% w / w,(iii) 1.00-10.00% w / w,(iv) 1.00-10.00% w / w, of which 1.00-5.00% w / w is zinc oxide <ZnO> and 1.00-5.00% is milled cork <MC>,(v) 0.10-1.00% w / w, and(vi) 0.25-2.00% w / w.

7. The biocomposite material according to any of the previous claims, wherein the optional functional additives are selected from the groups comprising: flame retardants: aluminium hydroxide <A1(OH)3>, hydromagnesite <Mgs (CO3) 4 (OH) 2 • 4H2O>, zinc borate <Zn3(BO3)2>, or mixtures of these substances, plasticizers: di ( 2-ethylhexyl ) adipate <DEHA>, dioctyl adipate <DOA>, diheptyl adipate <DHA>, heptyl adipate <HAD>, heptyl octyl adipate <HOA>, or mixtures of these substances, stabilizers: butylated hydroxytoluene <BHT>, butylated hydroxyanisole <BHA>, pentaerythritol tetrakis [3- (3, 5-di-tert-butyl ) -4 -hydroxyphenyl ) ropionate ] , octade cyl- 3- ( 3 , 5-di- tert-butyl-4-hydroxypheny) propionate, or mixtures of these substances , slip agents: calcium stearate, zinc stearate, erucamide, oleamide, stearamide, carnauba wax, candelilla wax, or mixtures of these substances, lubricants: C14-18 fatty alcohols like stearyl alcohol, metallic soaps like calcium or zinc stearate, higher fatty acids like palmitic acid, amide waxes such as N, N' -ethylene distearamide, glycerol esters with higher saturated fatty acids like glyceryl monostearate, glycerol esters of saturated hydroxy-derived fatty acids such as hydrogenated castor oil, glycerol partial esters of saturated fatty acids like mixtures of glyceryl monostearate and glyceryl dipalmitate, hydrocarbon waxes such as paraffin, polyethylene wax, or mixtures of these substances , biocides: 2-phenylphenol, chloroxylenol, 4-chloro-m-cresol, chlorhexidine and its salts, benzalkonium chloride, cetylpyridinium chloride, didecyldimethylammonium chloride, benzethonium chloride, benzoic acid, or mixtures of these substances , colorants: natural or synthetic mineral pigments like yellow iron oxide <Fe2O3-H2O>, red iron oxide <Fe2O3>, or black iron oxide <FesO4>, cobalt blue or cobalt (II) aluminate <CoA1204>, ultramarine violet, cobalt violet <Co3(P04)2>, manganese violet or ammonium manganese ( II ) pyrophosphate <NH4MnP20v>, chrome green <Cr2O3>, viridian or hydrated chromium ( III ) oxide<Cr2O3-H2O>, cobalt green or zinc green <CoZn02>, green earth or Verona green <K [ (Al, Fe3+) , ( Fe2+, Mg] (AlSis , Si4 ) Oio (OH ) 2>, malachite or basic copper carbonate <Cu2 (OH) 2CO3>, Prussian blue or iron (III) hexacyanoferrate ( III ) <Fe4 [Fe (CN) e] 3>, ultramarine, ultramarine violet, carbon black, vegetable black, manganese black or manganese dioxide <MnO2>, titanium white or titanium dioxide <TiO2>, lithopone <BaSO4-ZnS>, bronze powder, phthalocyanine blue BN pigments, phthalocyanine green G pigments, or quinacridone pigments, or mixtures of thesepigments, soluble organic dies such as azo dyes or lake pigments derived thereof, or mixtures of these substances, and fillers: natural milled or synthetic, precipitated calcium carbonate <CaC03>, talc tMgsSi^io (OH ) 2>, natural milled or synthetic precipitated barium sulfate <BaSO4>, or mixtures of these substances .

8. The biocomposite material according to any of the previous claims, wherein the drying oil <D0> is selected from the groups comprising:(a) raw, refined, stand, or boiled oils with an iodine number higher than 130, such as linseed oil <LO>, tung oil, poppy seed oil, perilla oil, or walnut oil,(b) stand oils made from semi-drying oils such as sunflower oil, soybean oil, corn oil, cottonseed oil, sesame oil, or grape seed oil, and(c) boiled oils made from: semi-drying oils such as sunflower oil, soybean oil, corn oil, cottonseed oil, sesame oil, or grape seed oil, and a siccative such as manganese, zirconium, iron, or zinc naphthenates , or mixtures of these substances, without or with the additional, catalytic amount, from 0.01-2.00% w / w, of said metallic siccative calculated to the weight of starting oil.

9. The biocomposite material according to claim 8, wherein the drying oil <DO> is linseed oil.

10. A process for preparing a biocomposite material according to claims 1-9, which includes the following manufacturing steps:A. drying of biodegradable polymer at 100-105 °C for 0.5-24 h,B. lignocellulose fibers are subjected to carding and drying at 100-105 °C for 0.5-24 h,C. nano-clay <NC>, antimicrobial additives <AMA>, and other optional additives are dried at 100-105 °C for 0.5-24 h, and then mixed with drying oil <DO> by kneading at room temperaturefor 15-30 minutes, yielding a coating mixture for the lignocellulose fibers,D. a coating of the dried lignocellulose fibers from Step B with the coating mixture from Step C,E. the dried biodegradable polymer from Step A is placed into the molds and subjected to melting at 180-200 °C for 5-15 minutes yielding thin sheets of 2-4 mm thickness, which are allowed to cool to 20-30 °C,F. the coated lignocellulose fibers from Step D are placed on the first thin sheet of the polymer obtained in Step E taking care that the coated lignocellulose fibers are oriented in one direction in the case of unidirectional composites, or in several directions in the case of multi-directional composites, andG. the thin polymer sheet with placed coated lignocellulose fibers from Step F is covered with the second thin polymeric sheet from Step E, and thus obtained sandwich-type structure is subjected to pressing at 185-195 °C for 160-200 seconds, at 25-40 kN with degassing for 30-60 seconds, yielding a sheet of the composite material.

11. Use of a biocomposite material according to any of claims 1-9, for manufacturing of industrial products as a substitute for conventional composite materials that are made from petrochemicalbased polymers .

12. Use of a biocomposite material according to claim 11, for manufacturing of different industrial products in the: automotive industry: interior components such as door panels, dashboards, trunk liners, construction: wall-, roofing-, or insulation panels, packaging industry: various packaging products, consumer goods: furniture, casings for various electronic products, sport goods, medical devices: orthopedic implants, dental materials, agriculture: biodegradable mulch films, plant pots,aerospace industry: various lightweight components and parts.

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