Field of invention:

The present invention relates to a bio-degradable composition for coating or composite material and preparation method thereof. More particularly, it relates to a liquid resin for appropriate coating of biodegradable materials such as recycled paper, kraft paper, virgin paper and recycled polymer films. Or disposable items for single use, such as shopping bags, packaging for fresh and processed food, plates, cups, spoons, straws and containers.

Background of the invention:

For over last six decades, fossil based polymers and plastics are widely used for manufacturing of single-layer, multi-layer composite and coating materials due to their performance, cost effectiveness and ease in mass-production. With increasing demand in food processing industries, demand for petroleum based single use packaging materials for food applications as well as cutlery has increased exponentially. There is now a need and movement driven by governments and consumers for increased use of Bio-degradable polymers to control pollution and climate change and restore the environment including our oceans, land, even air (as micro disintegrated non- degradable plastic particle), as whole, it has thrown huge challenges to us to find out better alternative to deal with above problem.

In the view of the above problem, bio-degradable coating and composite materials can be used as a solution posed by petroleum based plastics, as bio-based materials can break-down in the natural environment to its elements, i.e., carbon, hydrogen and oxygen within 6-12 months. Conventionally, several biodegradable polymers are already known in the state of the art and comprises of materials on the basis of e.g. poly(glycolic acid), poly(epsilon-caprolactone), poly(lactic acid), and polydioxanone and others . The production of these polymers is, however, rather cumbersome and expensive, so that the use thereof is presently mainly restricted to high value medical applications requiring bio-degradable & bio-absorbable materials.

A document for biodegradable materials used for packaging has been disclosed in International publication no. WO2012064798A1, that discloses food packaging which comprises of the one or more compostable polymers which are selected from the group consisting of a poly(hydroxyalkanoic acid), a poly(lactic acid), a polyesteramide; a polycaprolactone; an aliphatic copolyester and an aromatic copolyester.

The main drawback observed in the conventional composition is that the use of expensive starting materials &plasticizers does not provide the expected reduction in material costs. Hence, there is a need in the art to obviate the above problem and to provide materials, which combine the advantages of currently used plastics material and do not add to environmental pollution and, also, which remain cost and price competitive. Further, the bio-degradable liquid resin composition coated on paper or as a composite application will overcome the drawbacks of the conventionally used compositions.

Ob ject of invention:

The principle object of the present invention is to provide a bio-degradable composition for coating or as a composite material and preparation method thereof. The main object of the present invention is to provide a bio-degradable composition for coating which will result in reduction of material cost.

Another object of the present invention is to provide a bio-degradable composition for coating that is bio-compatible and flexible.

Further object of the present invention is to provide a bio-degradable composition for coating or as a composite material which will result in excellent oil resistance, water resistance, moisture resistance, oxygen resistance, mechanical strength and anti-bacterial properties.

One more object of the present invention is to provide a bio-degradable liquid resin composition coated on paper application which will overcome the drawbacks of the conventionally used composition.

Summary of the invention:

The present invention relates to a bio-degradable composition for coating or as a composite materials and preparation method thereof. The biodegradable composition is a liquid resinwhich is obtained by reaction of poly(glycerol sebacate) with nanomaterials. In various embodiments, the present invention provides method for adjusting the physical and chemical properties of the resultant composition, i.e. liquid resin and thus the ability to “tailor” a composition for final application. The obtained liquid resin is further coated on base paper and is dried. The coated base paper results in improvement of oil resistance, water resistance, moisture resistance, oxygen resistance, mechanical strength and anti-bacterial properties of the coated or composite material. Detailed description of the invention:

Before explaining the present invention in detail, it is to be understood that the invention is not limited in its application to the details. The invention is capable of other embodiments and of being practiced or carried out in a variety of ways. It is to be understood that the phraseology and terminology employed herein is for the purpose of description and not of limitation.

The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention.

A glycerol is also known as glycerin and liquid belongs to the alcohol family of organic compounds which is a natural chemical whose chemical formula is C3H8O3. Glycerol is colorless, odorless, hygroscopic, highly viscous syrupy liquid which is sweet in taste and is non-toxic in nature. Glycerol has been used in variety of applications like preserving food, as filler in commercially prepared low-fat food, cosmetic products etc.

A sebacic acid is also a natural occurring acid obtained from castor oil or decalin, whose chemical formula is C10H18O4. The sebacic acid has an appearance of white granular powder and is also low toxic and flammable. The acid has been widely used in applications of plasticizers, lubricants, cosmetics, candles etc.

A poly(glycerol sebacate) (PGS)is a glycerol-ester polymer which is synthesized from the polycondensation of the glycerol and the sebacic acid can be represented by the general formula as shown below in FIG. 1 below. The PGS has a wide application in field of biomedical and tissue engineering. PGS exhibits biodegradability as well as biocompatibility and cost effective production. PGS is a flexible elastomer with a nonlinear stress-strain nature whose physical and chemical properties, and degradation can be tailored to match the requirements of aimed applications by varying the reactants ratio, reaction condition, curing temperature and other process parameters.

FIG. 1

The nanomaterials of the present invention are selected but not limited to graphene, nanoclay, magnesium aluminum layered double hydroxide (MgAl-LDH), SiO2, silver nanoparticle, germanene (2D), stanene (2D), and titanium dioxide (TiO2).

Graphene is a monolayer of carbon atoms arranged in a hexagonal lattice. It is the thinnest two dimensional material and also incredibly strong (about 200 times stronger than steel). In addition of that, graphene has become excellent and useful nanomaterial because of its high tensile strength, conductivity and transparency.

Nanoclay is a nanoparticle composed of phyllosilicates which has a layered structure and can swell or shrink. Nanoclay is widely used in food packaging application. The use of less than 10% weight of nanoclay as additive found to improve the mechanical properties, tensile strength and tensile strain.

Layered double hydroxide has increasingly used due to its versatility and manipulating properties and their potential application in biomedical drug delivery, an anion exchangers, flame retardants etc. The electrocoagulation (EC) process using magnesium and aluminum offers a method of synthesis of layered double hydroxide results in magnesium aluminum layered double hydroxide.

Silicon dioxide is an amorphous material also known as silica, whose chemical formula is SiCL. SiCE is constituent of sand, and is one of the most complex and most abundant families of materials. Silicon dioxide is used in structural materials, food and pharmaceutical industries.

Silver nanoparticle (AgNPs) or colloidal silver is a nanosize particle(betweenl nm and 100 nm) of silver which uniquely changes the physical and chemical properties because of surface -volume ratio. The Ag nanoparticles are synthesized by electrolysis method of silver. This method achieves the availability of Ag nanoparticles in affordable prices. Due to its characteristic properties, it is widely used in variety of fields and application like medical, food, healthcare, consumer, industrial purposes, antibacterial agents, household, in consumer products, and medical device coatings etc.

Germanene is a mono layer of germanium atoms. Germanene has been prepared in high vacuum and temperature to deposit a layer of germanium atoms on a substrate and this thin film discloses 2D honey combbuckled structure properties used for semiconductor and materials science applications. Stanene is a nanomaterial composed of tin atoms placed in a mono, hexagonal layer structure. The main property of the stanene is that after the inclusion of spin-orbit coupling, it preserves the inversion and time -reversal symmetry. Stanene is useful in controlling individual electrons and nanoelectronic wiring etc.

Titanium dioxide is a naturally occurring oxide which is tasteless, odorless white powder with a molecular formula TiCT. Its molecular weight is 79.866 and pH of 7.5. Titanium dioxide has a wide application as a food coloring.

It is to be understood that a biodegradable composition for coating or composite material is aimed to achieve stability and structural integrity in mechanically dynamic environment. The biodegradable composition is synthesis under appropriate conditions with several hours of timing and temperatures to make it result in improved as well as excellent properties. The process for synthesizing of the biodegradable polymer is formulated by polycondensation of a multifunctional alcohol or ether and a dysfunctional or higher order acid.

The multifunctional alcohol or ether of the present invention is selected but not limited to glycerol.

The dysfunctional or higher order acid of the present invention is selected but not limited to glutaric acid, sebacic acid, adipic acid, pimelic acid, suberic acid, azelaic acid and tetradecanedioic acid. More preferably sebacic acid is used as the dysfunctional or higher order acid.

The base paper of the present invention is selected but not limited with weight (84 g/m ² ), thickness (99.25 pm), bulk (1.18 cm ³ /g) and density (0.85 g/cm ³ ) is used for coating purpose. Craft paper is used here, but not limited only craft paper. The biodegradable composition involves a portion that can berepresented by the general formula as shown below in FIG. 2, where a, b, c, d, and e are each independentlyintegers greater than 1. X can be graphene, or nanoclay, or magnesium aluminum layered doublehydroxide (MgAl-LDH) or SiOx, or silver nanoparticle, germanene (2d) and stanene(2d) materials. X canbe mixture of two or mixture of three or so on, of the above materials.

It should be appreciated that there is considerable overlap between the abovelisted nanomaterials in common usage, since a given nanomaterial is often classified differently by different practitioners in the field, or is commonly used for any of several different functions. Thus, the above-listed nanomaterials should be taken as merely exemplary, and not limiting, of the types of nanomaterials that can be included in composition of the present invention. One or more of these nanomaterials can be selected and used by the skilled artisan having regard to the particular desired properties of the dosage form by routine experimentation without any undue burden.

The present invention provides a bio-degradable composition for coating or composite material purposes which comprises following steps: Step 1: Polycondensation:

Before starting the operation ensure that the manufacturing area has a temperature 100°C under environment (which can be normal or inert environment). Record the change in reaction at each stage of manufacturing area at specified time which exhibits improvement in properties.

The present invention includes a biodegradable liquid resin composition for coating or composite material application which comprises 90-99.9 %w/w poly(glycerol sebacate), 5-0.01 %w/w graphene, 10-0.01 %w/w nanoclay, 5-0.01 %w/w magnesium aluminum layered double hydroxide (MgAl-LDH), 5-0.01 %w/w SiO2, 5-0.01 %w/w silver nanoparticles, 5-0.01 %w/w germanene (2d), 2-0.01 %w/w stanene (2d) and 5-0.01 %w/w titanium dioxide.

1. Add accurately weighed amount of reagents 100 gm (1.08 mole) glycerol and 202.25 gm (1.0 mole) sebacic acid mixed together in the three-necked flask at 100°C under environment (which can be normal or inert environment) for several hours.

2. Carefully reduce the pressure of the three-necked flask from ITorr to 40m Torr.

3. After reducing the pressure of the three-necked flask, the reaction is continued for several hours above 100°C under a reduced atmosphere.

4. Note after each hour the molecular weight, polydisperse index and degree of polymerization of obtained poly(glycerol sebacate) (PGS) pre-polymer.

Step 2: Coating and drying with or without nanomaterials addition:

A. 1. Accurately weighed 1.0 %w/w poly(glycerol sebacate) (PGS) prepolymer is coated on base paper. 2. Prepared coated base paper has been dried removing the water content in a control condition -100° C. The coated paper is dried till moisture content is not more than 6.0 %w/w.

3. Check and record the physical and chemical parameters of the coated base paper by varying the coating weight of pre-polymer resin.

B. 1. In another embodiment, accurately weighed 99.5 %w/w poly(glycerol sebacate) (PGS) pre-polymer and 0.05%w/w graphene nanomaterial mixed together for 1 hours at 80°C temperature.

2. The above obtained mixture of poly(glycerol sebacate) and graphene is then coated on base paper.

3. Prepared coated base paper has been dried removing the water content in a control condition -100 °C. The coated paper is dried till moisture content is not more than 6.0 %w/w.

4. Check and record the physical and chemical parameters of the coated base paper by varying the coating weight of above mixture resin.

C. 1. In another embodiment, accurately weighed 99.0 %w/w poly(glycerol sebacate) (PGS) pre-polymer and 1.0 %w/w nanoclay material mixed together for 1 hours at 80 °C temperature.

2. The above obtained mixture of poly(glycerol sebacate) and nanoclay is then coated on base paper.

3. Prepared coated base paper has been dried removing the water content in a control condition ~100°C. The coated paper is dried till moisture content is not more than 6.0 %w/w.

4. Check and record the physical and chemical parameters of the coated base paper by varying the coating weight of above mixture resin. D. 1. In another embodiment, accurately weighed 99.0 poly(glycerol sebacate) (PGS) pre-polymer and 1.0 %w/w magnesium aluminum layered double hydroxide (MgAl-LDH) nanomaterial mixed together for 1 hours at 80°C temperature.

2. The above obtained mixture of poly(glycerol sebacate) and magnesium aluminum layered double hydroxide (MgAl-LDH) is then coated on base paper.

3. Prepared coated base paper has been dried removing the water content in a control condition at ~100°C. The coated paper is dried till moisture content is not more than 6.0 %w/w.

4. Check and record the physical and chemical parameters of the coated base paper by varying the coating weight of above mixture resin.

E. 1. In another embodiment, accurately weighed 99 %w/w poly(glycerol sebacate) (PGS) pre-polymer and 0.5 %w/w magnesium aluminum layered double hydroxide (MgAl-LDH) and 0.5 %w/w nanoclay material mixed together for 1.5 hours at 85 °C temperature.

2. The above obtained mixture of poly(glycerol sebacate) and magnesium aluminum layered double hydroxide (MgAl-LDH) and nanoclay is then coated on base paper.

3. Prepared coated base paper has been dried removing the water content in a control condition at 100°C . The coated paper is dried till moisture content is not more than 6.0 %w/w.

4. Check and record the physical and chemical parameters of the coated base paper by varying the coating weight of above mixture resin. F. 1. In another embodiment, accurately weighed 98.5 poly(glycerol sebacate) (PGS) pre-polymer and 1.0 %w/w nanoclay and 0.5 %w/w titanium dioxide nanomaterial mixed together for 1 hours at 80 °C .

2. The above obtained mixture of poly(glycerol sebacate) and nanoclay andtitanium dioxide is then coated on base paper.

3. Prepared coated base paper has been dried removing the water content in a control condition at ~100°C The coated paper is dried till moisture content is not more than 6 %w/w.

4. Check and record the physical and chemical parameters of the coated base paper by varying the coating weight of above mixture resin.

G. 1. In another embodiment, accurately weighed 99.7 %w/w poly(glycerol sebacate) (PGS) pre-polymer and 0.03 %w/wgermanene nanomaterial mixed together for 1 hours at 70°C.

2. The above obtained mixture of poly(glycerol sebacate) and germanene is then coated on base paper.

3. Prepared coated base paper has been dried removing the water content in a control condition at ~100°C. The coated paper is dried till moisture content is not more than 6 %w/w.

4. Check and record the physical and chemical parameters of the coated base paper by varying the coating weight of above mixture resin.

H. 1. In another embodiment, accurately weighed 99.9 %w/w poly(glycerol sebacate) (PGS) pre-polymer and 0.01 %w/w silver nanoparticle mixed together for 1 hours at 80°C temperature.

2. The above obtained mixture of poly(glycerol sebacate) and silver nanoparticle is then coated on base paper. 3. Prepared coated base paper has been dried removing the water content in a control condition at 100°C. The coated paper is dried till moisture content is not more than 6.0 %w/w.

4. Check and record the physical and chemical parameters of the coated base paper by varying the coating weight of above mixture resin.

I. In various embodiments, the accurately weighed 98.5 %w/w poly(glycerol sebacate) can be mixed with 0.05 %w/w graphene, 0.5 %w/w nanoclay, 0.25 %w/w magnesium aluminum layered double hydroxide (MgAl-LDH), 0.25 %w/w SiOx, 0.01 %w/w silver nanoparticle, 0.001 %w/w germanene (2d), 0.001 %w/w stanene (2d) and ~0.4 %w/w titanium dioxide nanomaterials. The PGS can be mixed with one or three or all together nanomaterials at various ratios as per requirements of the final properties.

The invention is illustrated more in detail in the following example. The example describes and demonstrates embodiment within the scope of the present invention. This example is given solely for the purpose of illustration and is not to be construed as limitations of the present invention, as many variations thereof are possible without departing from the spirit and scope.

Example 1:

One accomplishment of the present invention may be illustrated by preparation of a biodegradable composition for coating or composite material purposes. Their preferred quantities are described in Table 1 below:

Table 1: Composition used in preparation of biodegradable liquid resin

A process for preparation of a biodegradable liquid resin comprises following steps:

Step 1: Polycondensation

1. 25gm (0.54mole) glycerol and 101.2 gm (0.5 mole) sebacic acid were mixed together in the three-necked flask at 100°C under environment (which can be normal or inert environment) for 1 hours.

2. The pressure of the three-necked flask was reduced from 1.0 Torr to 40 m Torr.

3. After reducing the pressure of the three-necked flask, the reaction was continued for 4 hours above 100°C under a reduced atmosphere.

4. After each hour the molecular weight, polydisperse index and degree of polymerization of obtained poly(glycerol sebacate) (PGS) pre-polymer was noted.

Step 2: Coating and drying with or without nanomaterials addition:

1. Accurately weighed 99.0 %w/w poly(glycerol sebacate) (PGS) pre-polymer and 1.0 %w/w nanoclay material were mixed together for 1 hours at 80 C temperature.

2. The necessary amount of the obtained mixture of poly(glycerol sebacate) and nanoclay was then coated on base paper.

3. Prepared coated base paper were dried by removing the water content in a control condition 101 °C The coated paper was dried till moisture content was not more than 6.0%w/w. 4. The physical and chemical parameters of coated base paper were recorded and checked.

Evaluation study:

The final product was evaluated through various physical and chemical parameters. The final coated base paper i.e. the biodegradable liquid resin composition coated on base paper which is formulated for coating or composite material purpose was used as a sample and was evaluated through various parameters. An observation was done on the basis of the various coating layer and weight of the coating resin applied on the base paper to show improvement in oxygen transmission rate, water vapor transmission rate and mechanical properties of the final coated base paper. The weighed amount of 25gm (0.54mole) glycerol and 101.2 gm (0.5 mole) sebacic acid were mixed together and at each stage of reaction timing, the below mentioned results were obtained.

Table 1: Polycondensation to form poly(glycerol sebacate)

From the above Table 1, for prepared poly(glycerol sebacate) it was observed that after 2 hours of reaction between glycerol and sebacic acid, prepolymer with number average molecular weight (Mn) 398, weight average molecular weight (Mw) of 430, polydisperse index (PDI) of 1.08 and degree of polymerization (DP) of 1.55 was obtained.

Further, after 3 hours of reaction between glycerol and sebacic acid, prepolymer with number average molecular weight (Mn) 647, weight average molecular weight (Mw) of 784, polydisperse index (PDI) of 1.21 and degree of polymerization (DP) of 2.84 was obtained.

Furthermore, after 4 hours of reaction between glycerol and sebacic acid, prepolymer with number average molecular weight (Mn) 1345, weight average molecular weight (Mw) of 1401, polydisperse index (PDI) of 1.041 and degree of polymerization (DP) of 5.07 was obtained.

Furthermore, after 5 hours of reaction between glycerol and sebacic acid, prepolymer with number average molecular weight (Mn) 1412, weight average molecular weight (Mw) of 1593, polydisperse index (PDI) of 1.12 and degree of polymerization (DP) of 5.77 was obtained.

After resulting poly(glycerol sebacate) of above mentioned properties, the prepared poly (glycerol sebacate) with weight average molecular weight (Mw) of 1401 99.0 %w/w poly(glycerol sebacate) was selected to eaxt with 1.0% w/w nanoclay and the obtained resin was coated on base paper. After that the below mentioned results were obtained.

Table 2: PGS with nanoclay shows improved properties of OTR and WVTR. Table 3: PGS with nanoclay shows improved mechanical properties.

From above Table 2 and 3, prepared liquid resin of poly (glycerol sebacate) and nanoclay mixture coated on base paper reveals that the single layer coating of the base paper with coating weight of 0 g/m ² results in >100000 cm ³ /m ² *24 hr*0.1 MP of oxygen transmission rate, 567 g/m ² *day of water vapor transmission rate, 41±3.2 MPa of tensile strength and 2.3±0.35% of tensile strain. When the single layer of coating was applied on base paper with coating weight of 0.46 g/m ² , it was observed that the oxygen transmission rate and water vapor transmission rate reached at 18877.3 cm ³ /m ² *24 hr*0.1 MP and 219 g/m ² *day respectively. Further, when single layer coating resin weight 1.03 g/m ² was applied, the oxygen transmission rate, water vapor transmission rate, tensile strength and tensile strain reached at 4800 cm ³ /m ² *24 hr*0.1 MP, 156 g/m ² *day, 49±3.8 MPa and 3.7±0.29% respectively. Furthermore, when single layer coating resin weight 1.54 g/m ² was applied, the oxygen transmission rate, water vapor transmission rate, tensile strength and tensile strain reached at 1501 cm ³ /m ² *24 hr*0.1 MP, 102g/m ² *day, 52±2.8 MPa and 3.9±0.21% respectively.

Further, it was observed that when double layer coating resin weight 4.02 g/m ² applied, the oxygen transmission rate and water vapor transmission rate reached at 116 cm ³ /m ² *24 hr*0.1 MP and 10 g/m ² *day respectively. Result:

The prepared biodegradable liquid resin in various embodiments of the present invention has shown marginally better significance in tensile strength, biodegradation rate, oxygen barrier, moisture barrier, and oil resistance properties of the coated paper.

The prepared biodegradable liquid resin coated on paper has shown higher significance with respect to oxygen transmission rate and water vapor transmission rate.

Considerable amount of nanomaterials added in PGS prepolymer in various embodiments of the present invention has significantly result in increasing physical, chemical and mechanical properties of the coated paper.

The prepared biodegradable liquid resin in various embodiments of the present invention can be used as heat seal adhesives and printing by adjusting the reactant ratio, reaction condition and other process parameters of the final product.

The prepared biodegradable liquid resin in various embodiments of the present invention facilitating the coating, molding and injection to form materials with structures for various uses like straw, cutlery etc.

Although the example as well as the process of preparation and use has been specifically described, it should be understood that variations in the preferred embodiment could be achieved by a person skilled in the art without departing from the spirit of the invention. It is also to be understood that the present invention is given with the understanding that this invention is intended only to be illustrations without serving as a limitation on the scope of the invention as defined in the claims.