Melt processable starch compositions

• US 6,709,526 B1
• Filed: 09/06/2001
• Issued: 03/23/2004
• Est. Priority Date: 03/08/1999
• Status: Expired due to Term

• Current Assignee: The Procter & Gamble Company
• Original Assignee: The Procter & Gamble Company
• Inventors: Mackey, Larry Neil, Bailey, Valerie Ann, Trokhan, Paul Dennis
• Primary Examiner(s): Bell, Mark L.
• Assistant Examiner(s): Hailey, Patricia L.
• Application Number:
  US09/914,965
• Time in Patent Office: 929 Days
• Field of Search: 127/29, 536/102, 523/1, 523/220, 524/47, 428/373
• US Class Current: 127/29
• CPC Class Codes: A61L 15/20 containing organic materials
• CPC Class Codes: A61L 15/28 Polysaccharides or their derivatives A61L15/225 takes precedence
• CPC Class Codes: A61L 15/42 Use of materials characterised by their function or physical properties liquid bandages A61L26/00
• CPC Class Codes: C08J 2303/02 Starch; Degradation products thereof, e.g. dextrin
• CPC Class Codes: C08J 5/18 Manufacture of films or sheets
• CPC Class Codes: C08L 2666/02 Organic macromolecular compounds, natural resins, waxes or and bituminous materials
• CPC Class Codes: C08L 3/02 Starch; Degradation products thereof, e.g. dextrin
• CPC Class Codes: C08L 3/12 Amylose; Amylopectin; Degradation products thereof
• CPC Class Codes: D01F 8/10 with at least one other macromolecular compound obtained by reactions only involving carbon-to-carbon unsaturated bonds as constituent
• CPC Class Codes: D01F 9/00 Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments
• CPC Class Codes: Y10T 428/24124 Fibers
• CPC Class Codes: Y10T 428/249924 Noninterengaged fiber-containing paper-free web or sheet which is not of specified porosity
• CPC Class Codes: Y10T 428/268 Monolayer with structurally defined element
• CPC Class Codes: Y10T 428/269 including synthetic resin or polymer layer or component
• CPC Class Codes: Y10T 428/2857 including metal or compound thereof or natural rubber
• CPC Class Codes: Y10T 428/29 Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
• CPC Class Codes: Y10T 428/2913 Rod, strand, filament or fiber
• CPC Class Codes: Y10T 428/2929 Bicomponent, conjugate, composite or collateral fibers or filaments [i.e., coextruded sheath-core or side-by-side type]
• CPC Class Codes: Y10T 428/298 Physical dimension
• CPC Class Codes: Y10T 442/3146 Strand material is composed of two or more polymeric materials in physically distinct relationship [e.g., sheath-core, side-by-side, islands-in-sea, fibrils-in-matrix, etc.] or composed of physical blend of chemically different polymeric materials or a physical blend of a polymeric material and a filler material
• CPC Class Codes: Y10T 442/3171 : Strand material is a blend of polymeric material and a filler material
• CPC Class Codes: Y10T 442/60 : Nonwoven fabric [i.e., nonwoven strand or fiber material]
• CPC Class Codes: Y10T 442/637 : Including strand or fiber material which is a monofilament composed of two or more polymeric materials in physically distinct relationship [e.g., sheath-core, side-by-side, islands-in-sea, fibrils-in-matrix, etc.] or composed of physical blend of chemically different polymeric materials or a physical blend of a polymeric material and a filler material
• CPC Class Codes: Y10T 442/642 : Strand or fiber material is a blend of polymeric material and a filler material
• CPC Class Codes: Y10T 442/643 : Including parallel strand or fiber material within the nonwoven fabric
• CPC Class Codes: Y10T 442/68 : Melt-blown nonwoven fabric
• CPC Class Codes: Y10T 442/681 : Spun-bonded nonwoven fabric
• CPC Class Codes: Y10T 442/697 : Containing at least two chemically different strand or fiber materials
• CPC Class Codes: Y10T 442/698 : Containing polymeric and natural strand or fiber materials
• CPC Class Codes: Y10T 442/699 : Including particulate material other than strand or fiber material

Abstract

The present invention relates to a starch composition comprising starch, a polymer that is substantially compatible with starch and has a weight-average molecular weight of at least 500,000 such that the polymer forms effective entanglements or associations with neighboring starch molecules, and preferably at least one additive to improve melt flow and melt processability. The additive may be a hydroxyl plasticizer, a hydroxyl-free plasticizer, a diluent, or mixtures thereof. The composition is melt processable on conventional thermoplastic equipment. The composition is especially suitable for uniaxial and biaxial extensional processes to make fibers, films, foams and like products.

Claims

1. A substantially homogeneous composition comprising:

(a) from about 20 to about 99.99 wt % of a starch, wherein the starch has a weight-average molecular weight ranging from about 1,000 to about 2,000,000; and

(b) from about 0.001 to about 10 wt % of a high polymer, wherein the high polymer is substantially compatible with the starch, and the weight-average molecular weight of the high polymer is at least 500,000.

2. The composition of claim 1 wherein from about 20 to about 99 wt % of the starch is amylopectin.

3. The composition of claim 1 wherein the weight-average molecular weight of the starch ranges from about 1,500 to about 800,000.

4. The composition of claim 1 wherein the weight-average molecular weight of the high polymer ranges from about 800,000 to about 22,000,000.

5. The composition of claim 4 wherein a solubility parameter of the high polymer and a solubility parameter of starch differ by less than 10 MPa^1/2.

6. The composition of claim 5 wherein the high polymer is selected from the group consisting of polyacrylamide and its derivatives;

polyacrylic acid, polymethacrylic acid, and their esters;

polyvinyl alcohol;

polyethyleneimine;

copolymers made from mixtures of monomers of the aforementioned polymers; and

mixtures thereof.

7. The composition of claim 1 further comprising at least one additive selected from the group consisting of a hydroxyl plasticizer having at least one hydroxyl group, a hydroxyl-free plasticizer, a diluent, and mixtures thereof.

8. The composition of claim 7 wherein the additive further comprises a material selected from the group consisting of oxidation agents, cross-linking agents, emulsifiers, surfactants, debonding agents, lubricants, processing aids, optical brighteners, antioxidants, flame retardants, dyes, pigments, fillers, proteins and their alkali salts, biodegradable synthetic polymers, waxes, low melting synthetic thermoplastic polymers, tacktifying resins, extenders, wet strength resins, and mixtures thereof.

9. The composition of claim 7 wherein the weight-average molecular weight of the starch ranges from about 1,500 to about 800,000, the weight average molecular weight of the high polymer ranges from about 800,000 to about 22,000,000, and the solubility parameter of the high polymer and the solubility parameter of the starch differ by 10 MPa^1/2.

10. The composition of claim 9 wherein the high polymer is selected from the group consisting of polyacrylamide and its derivatives;

polyacrylic acid, polymethacrylic acid, and their esters;

polyvinyl alcohol;

polyethyleneimine;

copolymers made from mixtures of monomers of the aforementioned polymers; and

mixtures thereof.

11. A substantially homogeneous composition prepared by mixing the following materials:

(a) from about 20 to about 99.99 wt % of starch, wherein the starch has a weight-average molecular weight from about 1,000 to about 2,000,000; and

(b) from about 0.001 to about 10 wt % of a high polymer, wherein the high polymer is substantially compatible with the starch and has a weight-average molecular weight of at least 500,000.

12. A process for preparing a substantially homogeneous composition, the process comprising the step of:

(a) providing a starch having a weight-average molecular weight from about 1,000 to about 2,000,000;

(b) providing a high polymer that is substantially compatible with starch and has a weight-average molecular weight of at least 500,000;

(c) providing at least one additive selected from the group consisting of a hydroxyl plasticizer having at least one hydroxyl group, a hydroxyl-free plasticizer, a diluent, and mixtures thereof; and

(d) mixing the starch, the high polymer and the additive together to form a substantially homogeneous composition,

wherein the substantially homogeneous composition comprises;

from about 20 to about 99.99 wt % of the starch, from about 0.001 to about 10 wt % of the high polymer, and a balance of the additive.

13. The process according to claim 12, wherein the step (d) comprises the steps of feeding the starch, the high polymer, and the additive into an extruder, and extruding a substantially homogeneous composition thereof.

14. A substantially homogeneous composition comprising starch, a high polymer, and at least one additive;

wherein the composition has;

(a) a melt shear viscosity of less than about 50 Pa·

s; and

(b) an extensional viscosity, which is at least 10 times greater than that of a comparative composition having no high polymer therein.

15. The composition of claim 14 wherein the composition has an uniaxial draw ratio ranging from about 5 to about 6000.

16. The composition of claim 14 wherein the composition has a melting temperature ranging from about 80°

C. to about 180°

C.

17. The composition of claim 14 wherein the at least one additive is selected from the group consisting of a hydroxyl plasticizer having at least one hydroxyl group, a hydroxyl-free plasticizer, a diluent and mixtures thereof.

18. A fiber comprising a substantially homogeneous composition comprising:

(a) from about 20 to about 99.99 wt % of starch, wherein the starch has a weight-average molecular weight ranging from about 1,000 to about 2,000,000;

(b) from about 0.001 to about 10 wt % of a high polymer, wherein the high polymer is substantially compatible with starch and has a weight-average molecular weight of at least 500,000.

19. The fiber of claim 18 wherein the average diameter of the fiber is less than 50 microns.

20. A film comprising a substantially homogeneous composition comprising:

(a) from about 20 to about 99.99 wt % of starch, wherein the starch has a weight-average molecular weight ranging from about 1,000 to about 2,000,000;

(b) from about 0.001 to about 10 wt % of a high polymer, wherein the high polymer is substantially compatible with starch and has a weight-average molecular weight of at least 500,000.

21. The film of claim 20 wherein the film has a thickness of less than 0.8 mils.