 Process for preparing vitamin D-lactones |
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| Derivatives of tetrahydro-1H-1,3-diazepine and hexahydro-1,3-diazocine |
| What is claimed is: 1. A compound selected from the group consisting of bases having the formula ##S... |
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| Penicillins |
| We claim: 1. A penicillin of formula: ##STR24## wherein R.sup.2 is hydrogen or a pharmaceutically ... |
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| Method of controlling filament formation in a glass fiber bushing |
| We claim: 1. A method of controlling the formation of filaments from a molten glass source in a ... |
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| Polyhalogenated carboxylic acids |
| We claim: 1. A compound of the formula ##STR6## wherein X.sub.1 is selected from the group ... |
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| Novel cyclopropane carboxylic acid esters |
| We claim: 1. A compound of the formula ##STR14## wherein X.sub.1 is selected from the group ... |
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| Powdered or granular solid pesticide composition |
| We claim: 1. A powdered or granular solid pesticide composition comprising 0.05 to 0.5 parts by ... |
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| Soft capsule coated with a film of carnauba wax and process for the preparation of the same |
| We claim: 1. A soft-gelatin capsule, comprising a core material containing a pharmaceutically ... |
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Degradable plastic
| Details |
Inventors: Reich, Murray; Hudgin, Donald E.;
Assignee:
Primary Examiner: Bagwill; Robert E.
Assistant Examiner:
Attorney, Agent or Firm: Burgess, Dinklage & Sprung
Films and containers are made from polymers of propylene such as polypropylene which contains a small amount of stabilizer whereby the rapid degradation rate of polypropylene can be controlled so that it will degrade after predetermined exposure to sunlight. This renders such products especially suited for agricultural mulch films, where they need not be removed after a growing season, and for throw-away containers where they will decompose in garbage dumps or if discarded as litter. The thermal history of the polymer will also affect its degradation rate. The rate is measured in terms of thermally adjusted Langley units (TALU) since it has been found that the ambient temperature affects decomposition as well as the Langley units of solar radiation exposure. |
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DETAILED DESCRIPTION What is claimed is: 1.
In the growing of an agricultural crop in a field in which the field is at least partially covered with a plastic film for a predetermined growth period, the improvement which comprises ascertaining, from the meteoroligical data for the geographic area in which said field is located, the amount of TALU for said predetermined growth period, and covering said field with a film having a thickness of the order of magnitude of about 1 to 2 mils and consisting essentially of about 0.
01 to 5% by weight of a stabilizer and polypropylene having a molecular weight in excess of about 40,000, the thermal treatment of said polypropylene prior to the time when it is applied to said field as a film having been such as to reduce its initial stability by at least about 5,000 TALU, said film having a stability approximately that of the TALU determined but at least about 8,000 but not in excess of about 35,000 TALU, whereby the film will degrade after said predetermined growth period, the degradation being accelerated or decelerated in accordance with the acceleration or deceleration of crop growth due to climatic conditions.
2.
The process of claim 1 wherein the film has a stability of at least about 10,000 TALU.
Description:
The present invention relates to shaped plastic structures which will degrade in predetermined time intervals.
A large proportion of the plastic products which are presently manufactured are intended to be used for relatively limited periods of time, after which the products are usually discarded or otherwise disposed of.
Examples of such plastic articles are packaging films; all kinds of food containers such as egg cartons, meat trays, and bottles; beer can holders; containers for beverages such as milk, soft drinks, and beer; disposable clothing; drinking cups, plates, and plastic cutlery; agricultural mulch films; films used for construction purposes such as temporary windows, and films for curing concrete; bottles; containers for detergents and other cleaning agents; containers for motor oils; garbage and litter bags; laundry bags; disposable clothing and diaper liners; disposable baby bottles, cosmetic and pharmaceutical containers; and many others
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Weight Loss and Supplements 
