초록 ▼

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 O2 permeability of at least 775,000 ml/m2.atm.24 hrs, a P10 ratio of at least 1.3, and a ratio of CO2 permeability to O2 per

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 O2 permeability of at least 775,000 ml/m2.atm.24 hrs, a P10 ratio of at least 1.3, and a ratio of CO2 permeability to O2 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. 1 illustrates how O2 permeability an R ratio vary for different coating polymers and microporous films.

대표청구항 ▼

1. A gas-permeable membrane which is useful in the packaging of respiring biological materials and which comprises(a) a microporous polymeric film comprising a network of interconnected pores such that gases can pass through the film, and (b) a crystalline polymeric coating on the microporous film,

1. A gas-permeable membrane which is useful in the packaging of respiring biological materials and which comprises(a) a microporous polymeric film comprising a network of interconnected pores such that gases can pass through the film, and (b) a crystalline polymeric coating on the microporous film, wherein (1) the pores in the microporous film have an average pore size of less than 0.24 micron; (2) at least 70% of the pores in the microporous film have a pore size of less than 0.24 micron; and (3) the polymeric coating (a) comprises a crystalline polymer having a peak melting temperature Tp of -5 to 40.degree. C., an onset of melting temperature To such that (Tp-To) is less than 10.degree. C., and a heat of fusion of at least 5 J/g; and (b) has a thickness such that the membrane (i) has a P10 ratio, over at least one 10.degree. C. range which includes Tp, of at least 1.3; (ii) has an oxygen permeability (OTR), at all temperatures between 20 and 25.degree. C., of at least 775,000 ml/m2.atm.24 hrs (50,000 cc/100 inch2.atm.24 hrs); and (iii) has a CO2/O2 permeability ratio(R) at 20.degree. C. of at least 1.5; the P10, OTR and R values being measured at a pressure of 0.035 kg/cm2 (0.5 psi).