NATURAL BIOPOLYMER THERMOPLASTIC FILMS
A thermoplastic film composition that includes a polymer blend of multiple inherently incompatible polymer components is described. The composition includes a polymer blend having about 5 wt. % to about 45 wt. % of a plasticized natural polymer, about 5 wt. % to about 40 wt % of a polyolefin, a biodegradable polymer, and a compatibilizer with both a polar and a non-polar moiety on the same polymer molecule. The total plasticized natural and biodegradable polymers constitute a majority or predominant phase (≧51 wt. %), while petroleum-based olefinic polymers form the minority phase. The composition can be made into a film containing at least one renewable, natural polymer component. Also described are the articles of manufacture that may use such films.
1 . A thin thermoplastic film prepared from a polymer blend system comprising: about 5 wt. % to about 40 wt. % of a polyolefin, about 5 wt. % to about 45 wt. % of a plasticized natural polymer, about 5 wt. % to about 75 wt. % of a biodegradable polymer, and about 0.5 wt. % to about 15 wt. % of a compatibilizer having both a polar and a non-polar moiety on the same polymer molecule, where total amount of natural and biodegradable components in said cast film constitute a majority phase of at least 53 wt. % of dry polymer blend.
2 . The thermoplastic film according to claim 1 , wherein said polymer blend system is substantially absent gel particles.
3 . The thermoplastic film according to claim 1 , wherein said total biodegradable components in said cast film constitutes at least 55 wt. % of polymer blend.
4 . The thermoplastic film according to claim 1 , wherein the amount by weight of each of the component classes may range as follows: polyolefin from about 7% to about 30%; plasticized natural polymers from about 5% to about 35%; biodegradable polymer from about 15% to about 65%; and compatibilizer from about 0.5% to about 12.5%.
5 . The thermoplastic film according to claim 1 , wherein said plasticized natural polymer is a thermoplastic starch, a thermoplastic plant protein, thermoplastic algae.
6 . The thermoplastic film according to claim 1 , wherein said biodegradable polymer is an aliphatic-aromatic copolyester, polycaprolactone, polyesteramides, modified polyethylene terephthalate, polylactic acid (PLA) and its copolymers, terpolymers based on polylactic acid, polyglycolic acid, polyalkylene carbonates (such as polyethylene carbonate), polyhydroxyalkanoates (PHA), poly-3-hydroxybutyrate (PHB), poly-3-hydroxyvalerate (PHV), poly-3-hydroxybutyrate-co-4-hydroybutyrate, poly-3-hydroxybutyrate-co-3-hydroxyvalerate copolymers (PHBV), poly-3-hydroxybutyrate-co-3-hydroxyhexanoate, poly-3-hydroxybutyrate-co-3-hydroxyoctanoate, poly-3-hydroxybutyrate-co-3-hydroxydecanoate, poly-3-hydroxybutyrate-co-3-hydroxyoctadecanoate, polybutylene succinate, polybutylene succinate adipate, polyethylene succinate.
7 . The thermoplastic film according to claim 1 , wherein said polyolefin is polyethylene, polypropylene, copolymer of ethylene and propylene, polyethylene-co-vinyl acetate, and mixture of tow and more polyolefins.
8 . The thermoplastic film according to claim 1 , wherein said compatibilizer is a polar monomer-grafted polyolefin.
9 . The thermoplastic film according to claim 1 , wherein said compatibilizer is a copolymer of at least one polar monomer and one or more olefinic monomers.
10 . The thermoplastic film according to claim 1 , wherein said compatibilizer is one of the following: a maleic anhydride, acrylic acid, glycidyl acrylate, glycidyl methacrylate, glycidyl acrylate, or other polar monomer grafted polyolefins.
11 . The thermoplastic film according to claim 1 , wherein said the thin film has a thickness from about 10 micrometers to about 40 micrometers.
12 . The thermoplastic film according to claim 1 , wherein said film has a compatibilized microstructure with finely dispersed minority component.
13 . The thermoplastic film according to claim 1 , wherein said film has a continuous phase of biodegradable polymers.
14 . The thermoplastic film according to claim 1 , wherein said film has a dispersed thermoplastic starch.
15 . The thermoplastic film according to claim 1 , wherein said film has a peak stress of at least 21 MPa in MD and 7 Mpa in CD.
16 . The thermoplastic film according to claim 1 , wherein said film has a strain-at-break at least 600% in MD and about 300% in CD.
17 . The thermoplastic film according to claim 1 , wherein said film has an energy-at-break of at least 70 Joules per cubic centimeter in MD and lat least 18 Joules per centimeter in CD.
18 . The thermoplastic film according to claim 1 , wherein said film also includes a pigment, an antioxidant, slips additives, and anti-blocking agents.
19 . The thermoplastic film according to claim 1 , wherein said pigment, antioxidant, slip additives, and anti-blocking agents, etc, are up to about 5 or 6 wt. % total.
20 . An absorbent consumer article comprising: a top sheet, a back sheet, an absorbent core situated between said top sheet and back sheet said back sheet comprising a film formed from a polymer blend having a plasticized natural polymer, a biodegradable polymer, a polyolefin, and a compatibilizer with both a polar and a non-polar moiety on the same polymer molecule, where total biodegradable components in said cast film constitute at a majority phase of least 53 wt. % of dry polymer blend.
21 . The absorbent consumer product according to claim 20 , wherein said product is: a diaper, an adult incontinence article, a feminine hygiene product, and other product for hygiene absorbent uses.
22 . A method of forming a film, the method comprising: providing a polymer blend including a plasticized natural polymer, a biodegradable polymer, a polyolefin, and a compatibilizer with both a polar and a non-polar moiety on the same polymer molecule, where total biodegradable components in said cast film constitute at a majority phase of least 53 wt. % of dry polymer blend; mixing said polymer blend under melt extrusion conditions; extruding said polymer blend, and forming a film sheet.