WO2011099837A1

WO2011099837A1 - Biodegradable molded products

Info

Publication number: WO2011099837A1
Application number: PCT/MY2010/000021
Authority: WO
Inventors: R. Mohanthas Narayanasamy
Original assignee: Narayanasamy R Mohanthas
Priority date: 2010-02-09
Filing date: 2010-02-09
Publication date: 2011-08-18
Also published as: CN102686803A

Abstract

The invention relates to a process of manufacturing 100% biodegradable molded products. The process includes the use of materials such as starch, and corn wastes such as corncobs, cornstem, corn roots and cornleaves. Accordingly, the corn wastes are pulverized and added to a determined ratio of water and starch to produce a pulp mixture. The pulp mixture is then molded into desired shape of products using determined amount of pulp mixture to prevent wastage. The biodegradable molded products require no coating for water resistance or trimming unlike previous products which are produced using conventional processes. These biodegradable molded products can be molded into various uses such as food catering utensils, packaging and containers for various industries. The resulting biodegradable product is inexpensive, 100% biodegradable and useful.

Description

Biodegradable Molded Products

Field of Invention

The invention relates to a process of manufacturing food grade biodegradable molded products. More particularly the invention relates to biodegradable products for containers used for packaging and storage.

Background of Invention

The use of plastics is common in the production of industrial materials for packaging, food catering utensils and many more. Examples of such plastics include polyethylene, polypropylene, poly (vinyl chloride), polyamides (nylons), polyesters and polyurethanes. These plastics are durable and they degrade extremely slow. The chemical bonds which make the plastics so durable make it equally resistant to natural processes of degradation. The use of non-biodegradable plastics materials poses a threat to the environment where toxic materials are continually disposed into landfills and into the environment in increasing quantities every year. Therefore, manufacturers have recently begun to make packaging materials from biodegradable materials such as starch.

Biodegradable (compostable) packaging materials made from biopolymers (BP) were introduced into the market to reduce the amount of conventional packaging material. Biodegradable plastics are plastics which are capable to being broken down or degraded when exposed to sunlight, water or moisture, bacteria, enzymes, some instances rodent pest or insect attack and other forms of biodegradation or environmental degradation. Bioplastics or organic plastics are a form of plastics derived from renewable biomass sources, such as vegetable oil, corn starch, pea starch or microbiota, rather than fossil-fuel plastics which are derived from petroleum. Examples of bioplastics include starch based plastics, polylactic acid (PLA) plastics and many more. Although they are considered as bioplastics, some but not all are biodegradable and hence provide no solution to eliminating or diminishing the threat of pollution to the global environment.

Attempts have been made to process starch on standard equipment and using known technology in the plastics industry. For example, U.S. Pat. Nos. 4,863,655; 5,035,930 and 5,043,196 disclose compositions and methods for making an expanded starch material having at least 45% by weight amylose content. High amylose starch content is expensive and makes the product very susceptible to shrinking and deterioration in hot humid and use storage conditions. This is not viable, for the end product must be resilient and dimensionally stable within the temperatures encountered during shipping, storage or usage.

None of the above mentioned inventions use or suggest the production of biodegradable molded products which are made completely of food grade materials wherein the main component or material used is derived from wastes of food crops making it very economically viable and an effective solution to eliminating or diminishing pollution of the earth. Other technologies are very much dependant for a large content of their products on crops which needs to be grown, harvested and processed. Hence, there is a need to come up with a process which essentially uses food grade materials in the composition, and which results in safer, biodegradable and chemical free molded products while highly resilient for various uses for a wide range of products, and at very economical price.

Summary of Invention

The invention relates to a process of manufacturing 100% biodegradable molded products. The process includes the use of materials such as starch and corn wastes. Corn wastes would comprise the whole crop excluding the corn kernel i.e such as corncobs, cornstem, cornroots and cornleaves. Accordingly, the corn wastes are pulverized and added to a determined ratio of water and starch to produce a pulp mixture. The pulp mixture is then molded into desired shape of products using determined amount of pulp mixture to prevent wastage. The molding process is carried out at elevated temperatures to give permanent form and shape to the molded product, whilst also to evaporate the water contained therein. The biodegradable molded products require no coating for water resistance unlike previous products which are produced using conventional processes. These biodegradable molded products can be molded into various uses such as catering utensils, packaging and containers for various industries. The resulting biodegradable product is inexpensive, biodegradable and highly resilient packaging material which is suitable for a wide range of consumer products.

Description of the Preferred Embodiments

The present invention provides a process of manufacturing 100% biodegradable molded products which uses corncobs, cornleaves, corn root or cornstem from corn wastes as its starting material. A preferred embodiment of the present invention is described herein. However, it is to be understood that limiting the description to the preferred embodiment of the invention is merely to facilitate discussion of the present invention and it is envisioned that those skilled in the art may devise various modifications and equivalents without departing from the scope of the appended claims.

Corn wastes are used as starting material in manufacturing the molded products. The corn wastes are collected from various sources preferably where corncobs, cornleaves, corn root or cornstems are regarded as wastes. These would be easily and cheaply available in areas where corn is grown, harvested and processed, which otherwise would be discarded.The corn wastes are removed of unwanted material, such as sand, earth particles before use. The corn wastes are thoroughly cleaned and washed to remove any unwanted foreign matter such as sand and dust. The corn wastes are then pulverized into pulp using pulverizing apparatus commonly used to pulverize plant materials.

The pulp is then mixed with approximately 20% to 50% of starch by weight of the gross weight. Tapioca starch is the preferred starch in this process. However, other starches such as sago starch, potato starch, sweet potato starch, cornstarch and rice starch can be used. Zein, which is a corn protein is optionally added into the mixture. The function of zein in this process is to act as a binder and to provide an improved resistance of the molded products against moisture and organic or non-organic solvents. Besides using zein, other binders, such as amylase, amylopectin, alginic acid, gum tragacanth, polyvinylpyrrolidone and carboxymethylceliulose may be used. A selected binder is added into the mixture at 1 %-2% by weight. Water is then added to the mixture of pulp and starch at the ratio of between 30% to 50% by weight.

Table 1 : Percentage ratio of each materials by weight.

The pulp mixture containing the pulp, starch, water and zein is then mixed thoroughly until the mixture is well mixed using common mixing apparatus. Typically, it takes about 15 to 30 minutes to form a moldable mixture. If necessary food grade colouring matter can be added into the pulp mixture to provide coloured products. It will be appreciated other agents, such as plasticizers, softening agents, or release agents known in the industry can be added. However, a longer mixing time is also an option as this will result in a whiter finishing of the molded products. If desired the molded product can be subjected to further treatment, such as surface finish, surface coating, surface decoration by the use or adoption of known process.

The ratio and amount of the moldable pulp mixture is determined earlier on prior to the molding process. A pre-determined weight of moldable mixture dependant on the intended end product is placed into a mold. The pulp mixture is then molded in the mold which is heated to a temperature of between i 50°C to 200^0 for approximately 20 seconds to 50 seconds. The parameters are also dependent of the materials used, composition of the pulp mixture and also the properties of the end products such as thickness, shape and size. The heating will harden the moldable pulp mixture into a molded article according to the mold used. The heating process removes the moisture from the moldable pulp mixture and shapes the article accordingly. The heating process also ensures the removal of microorganisms present in the moldable pulp mixture which could lead to defect in the molded products.

Once the molded product is shaped, it is then removed from the mold and cooled. The whole cycle of production takes up to 20 to 50 seconds. The molded product is then ready depending on whether it requires any need for trimming or minimal trimming unlike conventional processes whereby the end products requires further reconditioning. Optional spraying and painting of the finished molded product can be carried out using food grade material.

The proportion for each material in the moldable pulp mixture depends on the derived characteristics of the end product. For example, the composition of the corn waste and starch can vary between the range of 10% to 50% in the pulp mixture. Therefore, the amount of starch and water can be adjusted accordingly to make up the composition of the pulp mixture. Corncobs is the preferred embodiment for the production of certain products such as cups, plates, hamburger boxes etc. Other corn wastes such as corn leaves and corn stems can be incorporated together with corncobs and used in varying proportions for other different products such as packaging materials, containers and others. Besides that, the use of other corn wastes without the corncobs can also be used in varying proportions, depending on the end products.

The novelty of this invention lies in the use of corn wastes which are usually discarded after the useful parts of a corn especially the kernels have been removed for other uses. Besides that, the production of products using this process is chemical free. Therefore, this makes the products food grade, safer and very much cheaper compared to other products produced using other processes. The molded products are moisture resistant and organic or non-organic resistant. They are also suitable for microwave use and storage in cold temperatures. The amount of pulp mixture to be put into the mold is predetermined to result in minimal or no wastage.

Trimming is not required or is minimal unlike products produced using other current conventional processes wherein the products needs to be trimmed prior to use. This reduces costs of labour and energy. The finished molded products do not need to be sprayed with a coating for better finishing and resistance to moisture and various solvents. Coating is not required in this process when zein protein or other examples of binders as mentioned earlier is incorporated into the moldable pulp mixture prior to molding. Hence, without the need for trimming and spray coating the whole process consumes lesser energy, economical and also requires lower labour costs. Additionally, anti-fungal, anti-bacterial, masking agents to prevent odour or smell, food grade colouring agents can be added to the pulp mixture prior to molding the said products. Products made according to the process described herein includes but not limited to cups, sauces, bowls, plates, trays "clam-shell" containers, hamburger box with hinge and lock, and all kinds of industrial packing and storage item.

Claims

1. A process for manufacturing biodegradable food grade products of various shapes wherein the steps comprise of:

a. pulverizing corn wastes free from foreign matter into a pulp;

b. adding starch to the pulp;

c. adding water to the pulp;

d. mixing pulp mixture obtained from step (d) into a moldable mixture;

e. placing a determined amount of the moldable mixture into a mold;

f. pressing the moldable mixture into a molded product;

g. hardening the molded product by heating; and

h. removing the molded product from the mold.

2. A process as claimed in claim 1 wherein ratio for corn wastes is 30% to 60% by weight, starch is 20% to 50% by weight and water is 30% to 50% by weight.

3. A process as claimed in claim 1 wherein the corn wastes used is selected from corncobs, cornleaves, corn root and cornstem.

4. A process as claimed in claim 1 wherein a binder is included into the moldable mixture.

5. A process as claimed in claim 4 wherein the ratio of the binder is to the pulp mixture at 1 % to 2 % by weight.

6. A process as claimed in claim 4 wherein the binder used is selected from one or more from the group of zein, amylase, amylopectin, alginic acid, gum tragacanth, polyvinylpyrrolidone and carboxymethylcellulose.

7. A process as claimed in claim 1 wherein the starch used is selected from one or more from the group of tapioca starch, sago starch, potato starch, sweet potato starch, corn starch and rice starch.

8. A process as claimed in claim 1 wherein the temperature used while forming the molded product is within 150 °C to 200 °C.

9. A process as claimed in claim 1 wherein the forming of moldable products in the mold is between 20 seconds to 50 seconds.

10. A molded product produced according to claims 1 to 9.

1 1 . A process for manufacturing biodegradable food grade products of various shapes wherein the steps comprise of:

a. pulverizing cornwastes selected from corncobs, corn leaves, corn root or corn stem free from foreign matter in a ratio of 30% to 60% into a pulp;

b. adding starch used is selected from one or more from the group of tapioca starch, sago starch, potato starch, sweet potato starch, corn starch and rice starch to the pulp in the ratio of 20% to 50% by weight;

c. adding water to the pulp in the ratio of 30% to 50% by weight;

d. mixing pulp mixture obtained from step (c) into a moldable mixture;

e. placing a determined amount of the moldable mixture into a mold;

f. forming the moldable mixture into a molded product;

g. hardening the moldable mixture by heating to 150 °C to 200 °C ; and

h. removing the molded product from the mold.

12. A process as claimed in claim 1 1 wherein a binder is included into the moldable mixture.

13. A process as claimed in claim 11 wherein the ratio of the binder is to the pulp mixture at 1 % to 2 % by weight.

14. A process as claimed in claim 12 wherein the binder used is selected from one or more from the group of zein, amylase, amylopectin, alginic acid, gum tragacanth, polyvinylpyrrolidone and carboxymethylcellulose.

15. A process as claimed in claim 11 wherein the forming of moldable products in the mold is between 20 seconds to 50 seconds.

16. A molded product produced according to any claims 1 to 9 or claim 10 to 15. 7. A biodegradable food grade molded products wherein the products contain materials of corn wastes, starch and zein or other binders.