Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2000-02-18
2002-04-23
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S052000
Reexamination Certificate
active
06376583
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a process for preparing starched-based thermoplastic polymer compositions and the compositions prepared thereby.
U.S. Pat. No. 3,137,592 issued to Protzman describes a process which comprises mixing starch with about 22 percent to about 67 percent water based on the weight of the starch raw material dry substance. The starch may or may not be modified. The mixture of the starch and water is fed under pressure onto a rotating screw, advanced by means of the rotation of the screw while maintaining an increased temperature by means of external heaters and the shearing action of the screw. The material is mechanically worked in a confining chamber formed by the screw and barrel of the extruder and then transformed into a homogeneous viscous fluid mass.
U.S. Pat. No. 4,673,438 issued to Wittwer et al., describes a starch/water composition obtained by maintaining a starch/water composition at a water content of 5 to 30 percent by weight of the composition under controlled conditions of temperature and pressure, heating the starch/water composition under pressure above its glass transition temperature and melting point while maintaining said water content to form a melt and further heating and plasticizing the molten starch/water composition to dissolve the starch in the water to form melt as a molecularly dispersed solution of said melt.
U.S. Pat. No. 4,454,268 issued to Otey describes a process for preparing a starch-based film from a composition of a blend of starch, water and one or more polymers. Otey teaches that the starch should be highly gelatinized, which means that all or substantially all of the starch granules are sufficiently swollen and disrupted, that they form a smooth viscous dispersion in water. The mixture is then processed at 105° C. to 110° C. at elevated pressures and extruded as a film.
Mercier, C., Effect of Extrusion-Cooking,
Die Starke
29. Jahrg. 1977/ Nr. 2 S.48-52 (Mercier) describes a process for extruding unmodified potato starch having a moisture content before extrusion of 23 percent by weight using a semi-industrial twin-screw extruder.
Randall et al., “Development of Starch Based Plastics—A Reexamination of Selected Polymer Systems in Historical Perspective,”
Starch/Starke
45 (1993) Nr. 8, S. 276-280, has argued that the concept of “destructurization” is just a new name for an old concept of “gelatinization” of starch that first originated in the food industry. The term “gelatinization” refers to the process of disruption of the granular structure of starch by heating a starch suspension at temperatures in the range of 50° C. to 80° C.
In order to produce a satisfactory extruded article, starch must be combined with other polymers, because extrusion of starch alone produces a brittle, water-sensitive article. U.S. Pat. No. 5,095,054 issued to Lay et al., describes the preparation of starch-based compositions comprising destructurized starch and water-insoluble polymers.
Such prior art patents and publications do not describe compounding starch, water and thermoplastic polymers in the form of strands and then pelletizing the strands. Fabricators must purchase and maintain an inventory of the starch and thermoplastic polymers or handle powders of the starch and thermoplastic polymers for fabrication into a finished article. It would be desirable to provide a process for preparing a starch and epoxy-based thermoplastic polymer composition comprising compounding starch, epoxy thermoplastic polymer and water into a pellet form which is convenient and desirable for some fabricators.
SUMMARY OF THE INVENTION
The present invention is a process for preparing a starch-based thermoplastic hydroxy-functional polyether comprising (1) feeding from about 40 to about 98 weight percent starch and from about 2 to about 60 weight percent of a thermoplastic hydroxy-functional polyether derived from monomers containing one or more epoxy groups into a typical processing equipment, including thermoplastic, rubber and food mixing equipment, at a temperature and for a time sufficient to provide a compounded mixture of the components and then (2) forming the compounded mixture into pellets.
The hydroxy-functional polyether has been found to adhere strongly to starch. This adhesion, and the generally good physical properties of hydroxy-functional polyether, allows for the preparation of hitherto unknown materials with useful physical properties.
The starch-based thermoplastic compositions of the present invention are suitable for use in fabricating molded, extruded or foamed articles, containers, films film laminates, or coatings using conventional fabricating techniques such as extrusion, compression molding, injection molding, blow molding and similar fabrication techniques commonly used to produce such articles. Examples of such articles include films, foams, sheets, pipes, rods, bags, boxes, meat trays, egg cartons, cups and plates, cutlery, and other disposable consumer items. The compositions of the present invention are also suitable for use as adhesives and encapsulating agents.
DETAILED DESCRIPTION OF THE INVENTION
Preferably, the hydroxy-functional polyethers employed in the practice of the present invention are:
(1) hydroxy-functional polyethers having repeating units represented by the Formula I:
(2) hydroxy-functional polyethers having repeating units represented by the Formula II:
(3) hydroxy-functional polyethers having repeating units represented by the Formula III:
wherein R
1
individually represents a divalent organic moiety which is predominantly hydrocarbylene, or a combination of different organic moieties which are. predominantly hydrocarbylene; R
3
is
R
4
is
wherein R
2
is a divalent organic moiety which is predominantly hydrocarbylene or
R
5
is hydrogen or alkyl; R
6
is independently an organic moiety which is predominantly hydrocarbylene; R
7
is independently hydrogen or methyl; A is an amine moiety or a combination of different amine moieties; B is a divalent organic moiety which is predominantly hydrocarbylene; m is an integer from 10 to about 1000; n is an integer from 0 to about 100; and x and y are independently integers from 0 to 100.
The term “predominantly hydrocarbylene” is defined as a divalent radical that is predominantly hydrocarbon, but which optionally contains a minor amount of a heteroatomic moiety such as oxygen, sulfur, imino, sulfonyl, and sulfoxyl.
Representative divalent organic moieties useful as R
1
, R
2
and R
6
include alkylene, cycloalkylene, alkylenearylene, poly(alkyleneoxyalkylene), alkylenethioalkylene, alkylenesulfonylalkylene, alkylene substituted with at least one hydroxyl group, cycloalkylene substituted with at least one hydroxyl group, alkylenearylene substituted with at least one hydroxyl group, poly(alkyleneoxyalkylene) substituted with at least one hydroxyl group, alkylenethioalkylene substituted with at least one hydroxyl group, and alkylenesulfonylalkylene substituted with at least one hydroxyl group; and arylene, dialkylenearylene, diaryleneketone, diarylenesulfone, diarylene oxide and diarylene sulfide.
In the more preferred hydroxy-functional polyethers, R
1
, R
2
and R
6
are independently methylene, ethylene, propylene, butylene, pentamethylene, hexamethylene, heptamethylene, octamethylene, nonamethylene, decamethylene, dodecamethylene, 1,4-cyclohexylene, 1,3-cyclohexylene or 1,2-cyclohexylene optionally substituted with at least one hydroxyl group, p-phenylene, m-phenylene, or 2,6-naphthalene, diphenylene-isopropylidene, sulfonyldiphenylene, carbonyldiphenylene, oxydiphenylene, or 9,9-fluorenediphenylene and n is from 0 to 10.
Preferably, A is 2-hydroxyethylimino-,2-hydroxypropylimino-, piperazenyl, or N,N′-bis(2-hydroxyethyl)-1,2-ethylenediimino-; B is isopropylidenediphenylene, 1,3-phenylene, or 1,4-phenylene; and R
5
is hydrogen.
The poly(hydroxy ester ethers) represented by Formula I are prepared by reacting diglycidyl esters of aliphatic or aromatic diacids such as diglycidyl terephthalate, or diglycidyl ethers of dihy
Berry Tricia S.
Kirkpatrick Donald E.
Pawlowski David F.
Winkler Marie S.
Damocles Nemia C.
Rajguru U. K
Seidleck James J.
The Dow Chemical Company
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