Landec Corporation

Donald A Schultz

Raymond Clarke

Ray F Stewart

Steven P Bitler

Valentine Y Yoon

Bradley Marshall McClary

Ross S Tsugita

David A Kamp

Edward E Schmitt

David D Taft

Andrew W Larson

Mark A Wanthal

Paul A Meyers

Novel gas-permeable membranes which are particularly useful in the packaging of fresh cut fruit and vegetables, and other respiring biological materials. The membranes have an Opermeability of at least 775,000 ml/m.atm.24 hrs, a Pratio of at least 1.3, and a ratio of COpermeability to Opermeability (R) of at least 1.5, and are made by forming thin polymeric coatings on microporous polymeric films. Preferred coating polymers are side chain crystalline polymers. Preferred microporous films contain inorganic fillers, particularly such films based on ultrahigh molecular weight polyethylene or polypropylene. FIG.illustrates how Opermeability and R ratio vary for different coating polymers and microporous films.

Gas-permeable membrane

Novel modifying agents contain a sharply-melting crystalline polymer ingredient, preferably a side chain crystalline (SCC) ingredient, and an active chemical ingredient. Such modifying agents, especially when in the form of particles, can be placed in contact with a matrix, will not modify the matrix below the crystalline melting point T , but will rapidly modify the matrix above T . The active chemical ingredient can react with the matrix, catalyze a reaction of the matrix, or inhibit a reaction of the matrix. Particularly useful compositions are polymer precursors which are storage-stable at low temperatures but which are rapidly converted to crosslinked resins when heated to temperatures above T , optionally in the presence of light.

Polymeric modifying agents

Novel gas-permeable membranes which are particularly useful in the packaging of fresh cut fruit and vegetables, and other respiring biological materials. The membranes comprise a microporous film or other gas-permeable substrate and, coated on the substrate, a layer of a block copolymer having a heat of fusion of at least 5 J/g and containing polysiloxane polymeric blocks and crystalline polymeric blocks having a melting point of &minus;5 to 40&deg; C.

Packaging biological materials

Novel gas-permeable membranes which are particularly useful in the packaging of fresh cut fruit and vegetables, and other respiring biological materials. The membranes have an O permeability of at least 775,000 ml/m .atm.24 hrs, a P ratio of at least 1.3, and a ratio of CO permeability to O permeability (R) of at least 1.5, and are made by forming thin polymeric coatings on microporous polymeric films. Preferred coating polymers are side chain crystalline polymers. Preferred microporous films contain inorganic fillers, particularly such films based on ultrahigh molecular weight polyetheylene or polypropylene. FIG. illustrates how O permeability an R ratio vary for different coating polymers and microporous films.

Pressure-sensitive adhesive (PSA) compositions containing a crystalline polymeric additive having an M.sub.w of less than 25,000 and a melting point (T.sub.a) greater than 23.degree. C., preferably 30.degree. to 60.degree. , and PSA composites of a backing, preferably a flexible backing, with such a PSA composition coated thereon. The presence of the additive causes the PSA to lose adhesive strength when heated to T.sub.a. The base resin of the PSA is preferably a polyacrylate or a styrene/butadiene copolymer. The additive, which is preferably present in amount 1 to 35%, e.g. 5 to 30%, is preferably a side chain crystallizable (SCC) polymer.

Growing community of inventors

San Mateo, CA, United States of America

Donald A Schultz