Solar-reactive mulch film
OwnerDouglas Michael Trenchard, Robert Charles Trenchardinventors
Life of this patent
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Abstract
A solar reactive mulch film comprising one or more layers of heat shrink material pre-strained at a predetermined temperature and tension. Immediately cooling the pre-strained layers retains molecular deformation stresses in the material which facilitate shrinkage but not expansion on exposure to solar radiation. The mulch film adapted to be laid over longitudinal growing beds and held tautly by burying its side edges in soil. Exposure of uncovered portions of film to solar radiation causes shrinkage in one or more directions whereby in combination with the weight of the soil holding it down, maintains tautness of the mulch over a growing period. Methods of manufacture and use of the same.
Claims17
A solar-reactive agricultural mulch film comprising:
- a sheet of heat-shrink material including one or more layers of linear low density polyethylene (LLDPE) and/or metalocene linear low density polyethylene (mLLDPE), wherein one or more of the layers of LLDPE and/or mLLDPE having dispersed, in a polyethylene consisting essentially of LLDPE and/or mLLDPE, carbon black particles, in an amount that ranges between 2% and 8% by weight, that absorb radiant energy from sunlight and convert the radiant energy to heat, such that a surface temperature of the sheet is raised to at least a shrinking temperature of 40° C., which is above an ambient surface temperature of the sheet but not above a melting point of one or more of the layers of LLDPE and/or mLLDPE;
- and wherein, when one or more of the layers of LLDPE and/or mLLDPE is less than the shrinking temperature, each of one or more of the layers of LLDPE and/or mLLDPE is elongated, in a lengthwise direction, beyond a yield point of each of one or more of the layers of LLDPE and/or mLLDPE such that main chain molecules of the LLDPE and/or mLLDPE and/or side branched molecules of the LLDPE and/or mLLDPE in each of one or more of the layers of LLDPE and/or mLLDPE are aligned and elongated in the lengthwise direction and resultant plastic deformation stresses, resulting from elongation beyond the yield point, are retained and each of one or more of the layers of LLDPE and/or mLLDPE does not shrink.
Dependencies are inferred from the claim text.