GB1592062A - Biodegradable composition - Google Patents

Description

(54) BIODEGRADABLE COMPOSITION (71) We, COLOROLL LIMITED, a British Company of 54 Jermyn Street, London SW1Y 6LS, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention is an improvement of the invention forming the subject of our Patent No. 1,487,050 and relates to a biodegradable composition comprising a synthetic resin and natural starch granules.

According to Claim 1 of the Complete Specification of Patent No. 1,487,050 there is provided a biodegradable composition comprising a polymer håving carbon to carbon linkages and natural starch ganules, the such faces of said granules being modified, that is rendered hydrophobic, by reaction with a compound which readily reacts with hydroxyl groups to form an ether or an ester.

The specification is primarily concerned with compositions wherein the maximum biodegradable substance (starch) content is 50% by weight.

Preferably the composition will include an autoxidisable substance specifically a fatty acid, a fatty acid ester or a mixture thereof preferably in a concentration of up to 5-5% by weight of the composition as a whole as set out in Patent Specification No. 1,485,833.

Preferred synthetic polymers particularly for the construction of meat packaging trays are polystyrenes.

According to the present invention there is provided a gas-permeable and water repellant material for meat packaging such material comprising at least 60% by weight of starch granules rendered hydrophobic by reaction with a compound which readily reacts with hydroxyl groups to form an ether or an ester and a synthetic polymer.

The following examples illustrate the pre sent invention: EXAMPLE I Normal "pearl" corn starch containing 13% water was blended in a stirred open vessel with 0 5% of a silicone, hydrogen polydimethyl siloxane as manufactured by the Dow Chemical Corporation under the code number DC 1107. The temperature of the starch was raised progressively by a heated jacket to 1500C over a period of about six hours, and maintained at this temperature for a further period of about six hours. The resulting starch was a fine powder containing less than 0 5% of moisture and displayed hydrophobic properties to the extent that it would float on the surface of distilled water, even after brisk agitation.This hydrophobic starch was used in the following composition: ABS (acrylonitrile/butadiene/styrene) co-polymer "polystyrene" resin sold by Monsanto Company under the Registered Trade Mark "LUSTRAN" 100 parts by weight Starch rendered hydrophobic 175 parts by weight Ethyl oleate (autoxidi- 0-6 parts by weight Oleic acid S sable sub- 0 05 parts by weight stance) Titanium dioxide pigment 3 0 parts by weight (63% starch by weight of total composition) The ingredients were pre-blended in a spiral blade trough mixer when fluxed on a 2-roll mill, heated by steam at 90 psig and finally stripped from the mill as a smooth hide about 3 mm thick.This hide was subsequently thermoformed, after re-heating to 150"C, to make shallow dishes which were very strong and had a matt white appearance and a water repellant surface. The intended application is as meat packing trays, because the porosity of the composition allows the easy access of atmospheric oxygen through the body of the dish to the contacting surface of fresh meat placed in the dish, thus delaying the development of the discolouration familiar in the case of fresh meat packed on impermeable polystyrene dishes. Furthermore, the hydrophobic nature of the composition inhibits the absorption of blood from the meat into the body of the dish which would otherwise cause unsightly staining.

EXAMPLE II A suspension of maize starch was prepared in de-ionised water such that 1200 gr. of of starch was contained in every 4 litres of water, and the suspension was stirred whilst 43-2 gr. of a sodium siliconate preparation, Dow Corning 772, previously diluted to 100 gr. with de-ionised water was added, after which the pH of the system was adjusted to pH8 of the slow addition of dilute acetic acid. The starch granules are thus rendered hydrophobic. The suspension was then blended with a sufficient quantity of polyvinylidene chloride/acetate co-polymer emulsion as to produce a concentration of resin of 10% calculated on the dry weight of the starch.The suspension was then admitted to the spray system of a small spray drying unit with the atomising air pressure at 4 Kg/cm2 and an electrical power input to the air stream of 3Kw, which produced an inlet air temperature of 1700C and an outlet temperature between 70-800C. Under these conditions, a dry powder containing approximately 90% by weight of starch, could be compression-moulded at about 10 MN/m2 and 150"C to give quite strong hard white porous products. The intended applications are as in the previous Example.

WHAT WE CLAIM IS: 1. A gas permeable and water repellant material for meat packaging such material comprising at least 60% by weight of starch granules rendered hydrophobic by reaction with a compound which readily reacts with hydroxyl groups to form an ether or an ester and a synthetic polymer.

2. A material as claimed in Claim 1 which further includes a fatty acid, a fatty acid ester or a mixture thereof.

3. A material as claimed in either Claim 1 or Claim 2 wherein the said compound is a silicone.

4. A material as claimed in either Claim 1 or Claim 2 wherein the said compound is an isocyanate.

5. A material substantially as hereinbefore described in the Examples.

6. A meat packaging tray made of a material as claimed in any of the preceding

Claims (1)

1. claims.