DESC:Field of the Invention
The present invention relates to a biodegradable plastic obtained from a natural source and a process of preparing said biodegradable plastic.

Background
Plastics find a wide range of applications. One such area of application is in pack-aging industry. Majority of the plastics used in the packaging industry use polyethylene or polypropylene. However, such conventional plastics have a limitation of being non-biodegradable and are thus harmful for environment. Thus, attempts have been made to prepare biodegradable plastic. Biodegradable plastic refers to a plastic-like material which functions similar to plastic, and is made of natural sources and can be degraded naturally. One of the natural sources, which can be used to obtain biodegradable plastic is seaweed. However, a number of factors have restricted the use of seaweed to obtain biodegradable plastic.
For example, WO 2014108887 discloses bio-plastics obtained from seaweed. The bioplastic is obtained by immersing seaweed in water for a certain time so that its weight and water content increase; preparing the seaweed slurry by adding water; casting and drying the slurry; and decreasing the water content in the slurry. However, the bio-plastic obtained using this process is weak, has odor and a likelihood of fungal growth on the same with time. Also, as the seaweed is green or brown in color, the plastic obtained is opaque. Thus, although the bio-plastic disclosed in this document is biodegradable, the same has limited or no usage, especially in packaging industry which requires plastics to be transparent, odorless and have high tensile strength.
Thus, there is a need for a biodegradable plastic which is transparent, has a tensile strength comparable to that of conventionally used plastics, and does not suffer from the problems of bad odor and/ or fungal growth.

Summary
A process of preparing a biodegradable plastic using a seaweed is disclosed. Said process comprises treating seaweed with an alkali to obtain alkali treated seaweed; treating the alkali treated seaweed with an acid to obtain alkali-acid treated seaweed; immersing the alkali-acid treated seaweed in an aqueous medium followed by boiling to obtain a clear solution; and casting the clear solution to obtain said biodegradable plastic.

Brief Description of Drawings
Figure 1: Photograph of the biodegradable plastic obtained in trial described in Ex-ample 1;
Figure 2: Photograph of the biodegradable plastic obtained in trial described in Ex-ample 2.

Detailed Description
To promote an understanding of the principles of the invention, reference will be made to the embodiment and specific language will be used to describe the same. It will nevertheless be understood that no limitation of scope of the invention is thereby intended, such alterations and further modifications in the described product and such further applications of the principles of the inventions as disclosed therein being contemplated as would normally occur to one skilled in art to which the invention relates.
It will be understood by those skilled in the art that the foregoing general descrip-tion and the following detailed description are exemplary and explanatory of the disclo-sure and are not intended to be restrictive thereof.
Reference throughout this specification to “one embodiment” “an embodiment” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present dis-closure. Thus, appearances of the phrase “in one embodiment”, “in an embodiment” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.
In its broadest scope, the present disclosure relates to a biodegradable plastic ob-tained from a natural source. Specifically, the present disclosure relates to a biodegradable plastic obtained from seaweed. Said biodegradable plastic has a tensile strength higher than that of conventional plastics, is at least translucent and flexible. Further, said biode-gradable plastic has an ability to dissolve in water upon exposure for a few hours.
A process of preparing said biodegradable plastic from seaweed is disclosed. The said process comprises:
- treating the seaweed with an alkali to obtain alkali treated seaweed;
- treating the alkali treated seaweed with an acid to obtain alkali-acid treated sea-weed;
- immersing the alkali-acid treated seaweed in an aqueous medium followed by boil-ing to obtain a clear solution; and
- casting the clear solution to obtain said biodegradable plastic.
Seaweed in accordance with the present disclosure includes marine microalgae.
In accordance with an embodiment, the seaweed is treated with the alkali for a prolonged time period ranging between 1-3 months and preferably 3 months. In accordance with a related embodiment, the alkali and the seaweed are treated in a w/w ratio of 1:5 to 1:3 and preferably 1:2. Alkali treatment of seaweed for a prolonged period of time enables removal of low molecular weight materials and green part of the seaweed, such as protein, lipid, vitamins and minerals leaving harder mass containing carbohydrate (carrageenan, agar etc.) and fiber, which is light greenish in color. Thus, alkali treatment results in a semi-transparent mass. Also, the alkali treatment aids in inhibiting fungal growth and partial removal of the odor. In accordance with an embodiment, the alkali treatment may be carried out with any known alkali. Preferably, the alkali is sodium hydroxide (NaOH).
In accordance with an embodiment, the alkali treated seaweed may be washed with water before treatment with the acid.
In accordance with an embodiment, the alkali treated seaweed is treated with the acid for a time period ranging between 1 hour to 6 days and preferably 1 day. In accord-ance with an embodiment, the acid and the alkali treated seaweed are in a w/w ratio rang-ing between 10:3 to 20:3 and preferably 10:3. Subsequent treatment of the alkali treated seaweed with the acid causes further reduction in odor and the mass becomes light brown-ish and semi or completely transparent. In accordance with a related embodiment, the acid treatment may be carried out with any known acid. Preferably, the acid is acetic acid.
In accordance with an embodiment, the alkali- acid treated seaweed may be washed with water before immersing in the aqueous medium.
In accordance with an embodiment, the alkali-acid treated seaweed is immersed the aqueous medium in a w/w ratio of 1:7 to 1:20 and preferably 1:10.
In accordance with an embodiment, the aqueous medium comprises of water only. In accordance with an alternate embodiment, the aqueous medium comprises of additives. These additives may be selected from a group consisting of sodium salt of carboxy methyl cellulose (Na-CMC), guar gum and mixture thereof. In accordance with an embodiment, the additives are added in an amount ranging between 2-8 wt.%. By way of specific ex-ample, 2-4 wt.% of Na-CMC and 4-8 wt.% of guar gum w.r.t. dry mass of the seaweed is added. These additives impart additional properties to the biodegradable plastic. For ex-ample, guar gum imparts dry strength and Na-CMC reduces water wettability of the bio-degradable plastic.
In accordance with an embodiment, the aqueous medium may further comprise ad-ditional ingredients such as flavouring agents, colorants, glazing agent, plastisizer, antiox-idants or any other agents which could improve the properties of the biodegradable plastic.
In accordance with an embodiment, casting is carried out at a temperature in the range of 80 – 100 ºC and preferably at 100oC. In accordance with an embodiment, casting is carried out for a time period between 4 - 20 hours and preferably for 20 hours. In ac-cordance with an embodiment, casting is carried out on a Teflon tray.
In accordance with an embodiment, the biodegradable plastic has a tensile strength of at least 10 MPa and preferably 10-40 MPa. In accordance with a further embodiment, the biodegradable plastic is atleast semi-transparent or translucent.
In accordance with an embodiment, the biodegradable plastic can be formed, molded into a desired shape, thin films and sheets. The biodegradable plastic, without any limitation, can be used as containers, such as pouch, bag, as a wrap, such as sausage casing, as coating for soft capsules, and the like, as packaging material for consumer goods and the like.

Specific Embodiments are Described Below
Such a process of preparing a biodegradable plastic using a seaweed, the process comprising:
- treating seaweed with an alkali to obtain alkali treated seaweed;
- treating the alkali treated seaweed with an acid to obtain alkali-acid treated sea-weed;
- immersing the alkali-acid treated seaweed in an aqueous medium followed by boil-ing to obtain a clear solution; and
- casting the clear solution to obtain said biodegradable plastic.
Such a process, wherein the seaweed is treated with the alkali for a time period ranging between 1 to 3 months.
Such a process, wherein the alkali treated seaweed is treated with the acid for a time period ranging between 1 hour to 6 days.
Such a process, wherein the alkali and the seaweed are treated in a w/w ratio rang-ing from about 1:5 to 1:3.
Such a process, wherein the acid and the alkali treated seaweed are in a w/w ratio ranging from about 10:3 to 20:3.
Such a process, wherein the alkali-acid treated seaweed is immersed in the aqueous medium in a w/w ratio ranging from about 1:7 to 1:20.
Such a process, wherein the aqueous medium comprises of additives selected from a group consisting of sodium salt of carboxy methyl cellulose (Na-CMC), guar gum and mixture thereof.
Such a process, wherein the additive is added in an amount ranging between 2-8 wt.%.
Such a process, wherein the clear solution is cast at a temperature in a range of 80 – 100 ºC for a time period between 4 - 20 hours.
A biodegradable plastic obtained from a seaweed, said film being at least translu-cent and having a tensile strength of at least 10 MPa.

Examples:
The following examples are provided to explain and illustrate the preferred embod-iments of the process of the present invention and do not in any way limit the scope of the invention as described and claimed:
Example 1: 100 grams seaweed was treated with 5 grams NaOH and 50 mL water for 3 months. The alkali treated seaweed thus obtained was washed three times with water. 50 grams of this washed alkali treated seaweed was treated with 100 grams of glacial acetic acid for 24 hours followed by washing three times with water. After the acid treatment, 50 grams of the alkali-acid treated seaweed was immersed in 1 litre water followed by boiling to obtain a clear solution. The clear solution was then cast overnight at 80º C.
Observations: Semi- transparent, smooth thin film was obtained. The tensile strength of the film was found to be 7-10 MPa. Biodegradable plastic obtained has been shown in Figure 1.
Example 2: Quantity of acid, acid treatment time and quantity of water were varied in Example 2, as compared to Example 1.
100 grams seaweed was treated with 5 grams NaOH and 50 mL water for 3 months. The alkali treated seaweed thus obtained was washed three times with water. 50 grams of the washed alkali treated seaweed was treated with 1:1 aqueous acetic acid (i.e. 50 grams of glacial acetic acid and 50 grams of water) for 1-6 days followed by washing three times with water. After the acid treatment, 50 grams of the alkali-acid treated sea-weed was immersed in 700 ml water together with 0.3 gram of Na-CMC and 0.6 gram of guar gum, followed by boiling to obtain a clear solution. The clear solution was then cast overnight at 100º C.
Observations: Transparent, flexible films were obtained from materials treated with acetic acid for up to 6 days. The tensile strength of the films was found to be in the range of 12-23 MPa, depending on the time of treatment with acid. The biodegradable plastic obtained after treatment with acid for 6 days has been shown in Figure 2.

Industrial Applicability
The disclosed process of preparing the biodegradable plastic obtained from sea-weed, as described above is environment friendly and inexpensive. The biodegradable plastic obtained from disclosed process is at least translucent, biodegradable, odorless and insusceptible to fungal growth. Also, said biodegradable plastic has a tensile strength same/ higher than that of conventional plastics, is at least translucent and flexible. Said biodegradable plastic thus finds applications in various industries and could replace the conventional non-biodegradable plastics. A blend of said biodegradable plastic may also be formed with biodegradable plastics obtained from natural sources, other than seaweed. ,CLAIMS:We Claim:

1. A process of preparing a biodegradable plastic using a seaweed, the process com-prising:
- treating seaweed with an alkali to obtain alkali treated seaweed;
- treating the alkali treated seaweed with an acid to obtain alkali-acid treated sea-weed;
- immersing the alkali-acid treated seaweed in an aqueous medium followed by boil-ing to obtain a clear solution; and
- casting the clear solution to obtain said biodegradable plastic.

2. A process as claimed in claim 1, wherein the seaweed is treated with the alkali for a time period ranging between 1 to 3 months.

3. A process as claimed in claim 1, wherein the alkali treated seaweed is treated with the acid for a time period ranging between 1 hour to 6 days.

4. A process as claimed in claim 1, wherein the alkali and the seaweed are treated in a w/w ratio ranging from about 1:5 to 1:3.

5. A process as claimed in claim 1, wherein the acid and the alkali treated seaweed are in a w/w ratio ranging from about 10:3 to 20:3.

6. A process as claimed in claim 1, wherein the alkali-acid treated seaweed is im-mersed in the aqueous medium in a w/w ratio ranging from about 1:7 to 1:20.
7. A process as claimed in claim 1 or 6, wherein the aqueous medium comprises of additives selected from a group consisting of sodium salt of carboxy methyl cellu-lose (Na-CMC), guar gum and mixture thereof.

8. A process as claimed in claim 7, wherein the additive is added in an amount rang-ing between 2-8 wt.%.

9. A process as claimed in claim 1, wherein the clear solution is cast at a temperature in a range of 80 – 100 ºC for a time period between 4 - 20 hours.

10. A biodegradable plastic obtained from a seaweed, said film being at least translu-cent and having a tensile strength of at least 10 MPa.

Dated this 16th day of January, 2015

Aparna Kareer
Of Obhan & Associates
Agent for the Applicant
Patent Agent No. 1359