DE69737074T2 - Process for producing an elastic, biodegradable packaging material - Google Patents

Description

AREA OF INVENTION

These The invention generally refers to expanded, biological degradable, strength containing products with improved flexibility, suppleness or elasticity and other properties for use as packaging materials, especially for extruded webs, cast shells or other packaging containers are. The invention relates to improved methods of preparation of an expanded product of starch and starch containing compositions for feeding extruders.

BACKGROUND THE INVENTION

biological degradable materials are currently in greater demand for applications as packaging materials. The conventionally used polystyrene ("Styrofoam" (trade mark)), polypropylene, Polyethylene and other non-degradable, plastic-containing packaging materials are considered environmentally harmful considered. The use of such non-degradable materials will sink, because restrictions by the government's use in packaging applications too prevent looking. Biodegradable materials that are flexible, supple and not brittle are used in a variety of packaging applications, in particular for the Producing molded, biodegradable containers for food packaging needed.

For such Applications, the biodegradable material must have mechanical properties which make it possible to that this in the desired Brought container shape will and keeps this shape and resistant is against squeezing, Tear or breaking. additionally Be biodegradable materials with elasticity, compressibility and fill density, which are comparable to "Styrofoam" (brand) - "Peanuts", in loose filling packaging materials needed. Furthermore, biodegradable sheetings are needed which Have properties with polypropylene and polyethylene materials comparable, for example for the coating of packaging materials.

Strength is an abundant, inexpensive, biodegradable polymer. A variety of biodegradable, starch-based materials has been proposed for use in packaging applications. conventional Extruding starch produces expanded products that are brittle, sensitive to water and not suitable for the production of packaging materials are. Trials based on strength Products with flexibility, suppleness or elasticity and others mechanical properties necessary for various biodegradable Packaging applications are suitable to produce in the General on chemical or physicochemical modification of Strength, the use of expensive high-amylose starch or mixing starch with concentrated synthetic polymers to obtain the desired properties, while the biodegradability is maintained. A number of sources refers to extruding and injection molding starch-containing compositions.

U.S. Patents 4,133,784, 4,337,181, 4,454,268, 5,322,866, 5,362,778 and 5,384,170 refer to films based on starch and which Extrusion of destructured or gelatinized starch in combination be made with synthetic polymer materials. U.S. patent 5,322,866 relates in particular to a process for the preparation of biodegradable, starch blown films containing a step of extruding a mixture of crude unprocessed starch, copolymers, including polyvinyl alcohol, a nucleating agent and a plasticizer. From This procedure claims that there is no pretreatment of the Strength requires. U.S. Patent 5,409,973 discloses biodegradable Compositions obtained by extruding destructured starch and an ethylene-vinyl acetate copolymer.

US Patent 5,087,650 relates to injection molding of mixtures of graft polymers and starch to produce partially biodegradable products having acceptable elasticity and water stability. US Patent 5,258,430 relates to the preparation of biodegradable articles of destructured starch and chemically modified polymers, including chemically modified polyvinyl alcohol. The manufactured articles are said to have improved biodegradability but retain the mechanical properties of articles made solely from the polymer. US Patent 5,292,782 relates to extruded or injection molded biodegradable articles made from blends of starch, a thermoplastic polymer and certain plasticizers. US patent 5,403,875 relates to blends of starch with acrylic polymers which have been melt-processed into thermoplastic articles. US Patent 5,393,804 relates to biodegradable compositions made from starch melts containing converted starch and plasticizers including polyvinyl alcohol. US Patent 5,095,054 relates to methods of making shaped articles from a mixture of destructurized starch and a polymer.

U.S. U.S. Patent 4,125,495 relates to a method for making meat bowls from biodegradable starch compositions. Become starch granules chemically modified, for example mixed with a silicone reagent with polymer or copolymer, and brought into shape to a biological form degradable flat shell.

U.S. U.S. Patent 4,673,438 relates to extrusion and injection molding of Strength for the Production of capsules. U.S. Patent 5,427,614 also relates an injection molding process in which a non-modified starch with a lubricant, structurant, and a melt flow accelerator combined.

U.S. Patents 4,863,655, 5,035,930 and 5,043,196 disclose expanded Starch materials, in which the strength at least 45% by weight of amylose (high amylose materials). Expanded high amylose starch compositions were also modified by reaction with oxiranes (eg ethylene oxide) and include the commercially available "ECO-FOAM" (Trade Mark), in which the starch is reacted by reaction modified with propylene oxide. Expanded packaging materials, made from high-amylose starch are, are for practical commercial use too expensive. U.S. Patent 5,314,754 by Knight (May 24, 1994) discloses the production of molded Articles made of high-amylose starch.

The application published by the EP EP 712883 (Disclosed May 22, 1996) relates to biodegradable, structured, molded products with good flexibility made by extruding starch of a defined large particle size (e.g., 400 to 1500 microns). However, the application only discloses the use of high amylose starch and chemically modified high amylose starch.

US Pat. No. 5,512,090 relates to an extrusion process for producing low density elastic biodegradable packaging materials including loose fillers by extruding starch mixtures including polyvinyl alcohol (PVA) and other ingredients. The patent refers to a minimum amount of about 5% by weight of PVA. In US 5,186,990 a lightweight, biodegradable packaging material is disclosed which is made by extruding corn grit mixed with a binder (guar flour) and water. Corn meal is said to contain, among other ingredients, starch (76-80%), water (12.5-14%), protein (6.5-8%) and fat (0.5-1%) , US Pat. No. 5,208,267 discloses biodegradable, compressible and elastic starch-based bulking packages of high volume and low weight. The products are formed by extruding a blend of unmodified starch with polyalkylene glycol or certain derivatives thereof and a bubbling agent such as silicone dioxide. U.S. Patent 5,252,271 to Hyrum (12 October 1993) discloses a biodegradable, lightweight closed cell packaging material formed by extruding modified starch. Unmodified starch is reacted in an extruder with certain mild acids in the presence of water and a carbonate compound to produce CO ₂ . The elasticity of the product should be 60% to 85% with a density of less than 0.032 g / cm ³ .

U.S. U.S. Patent 3,137,592 relates to gelatinized starch products which for coating applications useful are and by intensive mechanical treatment of starch / softener mixtures be prepared in an extruder. Similar coating mixtures are disclosed in U.S. Pat. Patent 5,032,337 which by extrusion of mixtures of starch and polyvinyl alcohol. Applying thermomechanical Treatment in an extruder modifies the properties of solubility the resulting mixture, which is then used as a binder for coating can be used by paper.

EP-A-0 541 050 refers to a melt-spinning process Fibers of starch, which for the production of fabrics and fleece materials for bags, towels, Nets, diapers, cotton wool or filters can be used.

GB 965,349 refers to improvements in extruding amylose material used in the manufacture of films and fibers.

Even though Significant progress has been made with regard to non-brittle, up Strength based biodegradable packaging materials remains nevertheless a substantial need after lowering the production costs and improving the physical and mechanical properties of extruded starch materials.

SUMMARY THE INVENTION

The The present invention discloses a method of manufacturing biodegradable expanded starch products with improved properties for Packaging applications according to the claim 1.

It was found to be combined with compression by compression Stretching on strength based extrudates essential the flexibility, suppleness, mechanical strength and size stability of the extruded, injection molded packaging container is improved. The preferred method for compression of the extrudate is rolling. It was also found that compression or Roll the elasticity extruded, low density expanded starch articles improved, such as those useful for loose fill applications. Significant reductions in the brittleness of extruded products out of strength by compressing, rolling, compressing and stretching or Rolling and stretching of the material obtained after extrusion. The Apply the method according to this Invention allows the production of expanded packaging materials from starch with mechanical properties suitable for packaging applications are, using much smaller amounts of expensive polymeric plasticizers, for example polyols such as polyvinyl alcohol.

In The process of the present invention can put pressure on the resulting Extrudate can be applied in one direction, which in general perpendicular to the extrusion direction. Pressure is essentially applied perpendicular to the direction of extrusion. The applied Pressure is preferably sufficient to keep the cells in the extrudate to compress substantially. Surprisingly becomes the conviction that substantial compression, or preferably compression, the cells of the expanded product the flexibility, suppleness or elasticity significantly improves the product and significantly reduces brittleness. The mode of applying pressure to the extrudate is rolling the Extrudates between them Rollers. The amount of applied pressure may vary depending on the desired Final properties of the material vary. The rolling is preferably carried out, while that Extrudate is still warm, more preferably immediately after ejection of the extrudate from the extruder injection port.

In another embodiment Stretching can be used, for example, by pulling the extrudate strand essentially in the direction of extrusion faster than the extrusion speed. Extruding can be done are using conventional Methods and apparatus. The size, the shape and / or the applied stretch ratio are adjusted the desired final To provide properties in the extruded product. The stretched extrudate will continue molding, casting and / or cut to a desired, final shaped To receive articles that are for the intended use is suitable. Stretches of strength-based Extrudates significantly improves the final properties of molded including extruded items injection molded packaging containers.

In another embodiment In the process, the extrudate is stretched, for example, by drawing of the extrudate strand, allowing this the injection port at a speed faster than the extrusion speed leaves. Preferred stretching ratios are in the range of about 1.1 to about 1.5.

The Extrudate can be stretched before, after or simultaneously with compression become. Preferably, the stretching becomes simultaneous with the compression carried out. The preferred way to compress and stretch the extrudate is to use rollers where the rolling speed set higher is considered the extrusion speed. In this case, the extrudate both rolled and stretched. Roller speeds for stretching become common to less than or equal to 50% higher than the extrusion speed set. Preferred rolling speeds for stretching are between about 10% and about 20% higher as the extrusion speed. The desired amount of stretching, however, depends from the desired ones Final properties of the product as used here, a roller speed of 10%, 20% or 50% higher as the extrusion speed means a draw ratio of Extrudates of 1,1, 1,2 or 1,5.

The compressed and stretched expanded product is made of starch biodegradable and has low brittleness and other properties, it for make use in packaging applications interesting.

In an embodiment The present invention provides improved webs of padding strength. and packaging applications. Webs are preferably by rolling or rolling and stretching the extrudate, using a flat roller. Rolled expanded sheets of starch are generally useful in packaging and wrapping applications and in the manufacture of coated materials for packaging applications, such as for the production of envelopes and related containers. Webs from one layer, two layers or multiple layers can be through the Process of the present invention are formed.

In another embodiment This invention provides improved shaped articles of starch, in particular Articles made from extruded compressed and stretched webs out of strength be injection molded. Tracks for Injection molded articles are preferably rolled or rolled and stretched. Injection molded items can be of various sizes and sizes Have forms, including shallow and deep bowls, cups, tubs, pipes or others Containers. Injection molded articles can also bowls or containers with one or more subjects be and can also with inner or outer strips, edges or edges are formed. The extrudate of starch is rolled and / or stretched, before it is injection-molded. In injection molding, conventional methods and equipment can be used become.

In a still other embodiment This invention provides improved expanded materials Strength, the high elasticity, suitable compressibility, low density, low dust and a low brittleness for use in loose fill packaging applications exhibit. These improved starch materials are characterized by what is described herein Method by extrusion in combination with a step of Compressing or preferably substantial upsetting of the cells in the extrudate, preferably by rolling the hot extrudate, produced. Loose filling material can be made in a variety of shapes by choice suitable combinations of shapes of spray openings and rollers. The present Invention provides a loose expanded starch filling product an elasticity of more than 50%, which for Packaging applications is usable. Loose fillers of the present Invention have compressibility and flexibility properties comparable to the loose filling material "Styrofoam".

The Methods of the present invention can be used with substantially anyone Starch composition used which is suitable for extinction. In particular and preferably can the process with starch compositions in which the main ingredient is crude, unmodified Strength is. The method of the present invention enables Use of significantly less amounts of plasticizers in the extruder feed, as previously known to desired mechanical properties in the final expanded or injection molded Products made of starch to obtain.

The The invention also provides extruder feed mixtures containing crude, unmodified starch to produce expanded products from starch, the lower ones Amounts of plasticizers, especially smaller amounts of polymeric Plasticizers such as PVA and related polyols. To lower production costs Preferably, extruder feed mixtures include extruder feed mixtures less than 5% (by weight) PVA or related polyhydric softeners. More preferred extruder feed blends include less than or equal to 2.5% PVA or related polyhydric softeners. Very preferred Extruder feed blends do not include PVA or related polyhydric Plasticizers.

It It was found that lighter expanded items made of starch and expanded injection-molded articles made of starch with good mechanical Strength and size stability the process of the present invention from extruder feed mixtures, which include talc can be produced.

In another embodiment This invention provides a new extrusion apparatus in which conventional Extruder combined with a printing device, the pressure on an extrudate discharged from an extruder injection port, can apply substantially perpendicular to the extrusion direction. Of the applied pressure is sufficient to keep the cells in the warm extrudate to compress substantially or preferably to compress. The height of the applied Pressure and the duration of the application time of the pressure depends on the wished final Properties of the product.

Additional aspects and features of the invention will become apparent in the following detailed description practice of the invention.

SHORT DESCRIPTION THE DRAWING FIGURES

1 Figure 3 is a schematic representation of an extruding / rolling or extruding / rolling and drawing apparatus useful for carrying out the method of the present invention.

2 is a schematic representation of a Strömungsglätters that in the device 1 is used.

3 Figure 3 is a schematic representation of an extruding / compressing / cutting apparatus adapted to produce loose filling products of the present invention.

4a - 4e illustrate various roller assemblies that are suitable for use in the manufacture of loose fill products of the present invention.

Roll arrangements, which have 3 or 4 flat or shaped rollers are shown.

PRECISE DESCRIPTION THE INVENTION

The method for producing shaped, extruded articles of starch according to the present invention will be made with reference to the schematically illustrated production extruding device 1 described. Raw, unmodified starch is mixed with desired additives, for example in an attached feeder ( 1 ), through a feed tube ( 2 ) and in the mixing section of an extruder ( 3 ), preferably a twin-screw extruder, for example through an inlet ( 4 ) brought in. The feed tube ( 2 ) includes a flow straightener ( 5 ). The mixture is further mixed and subjected to shear, temperature rise, and pressure in the extruder to form a mass which passes through an expanding injection port (Fig. 7 ) is pressed. The mass is preferably a homogeneous, warm melt. Preferably, the mass is plasticized.

As in 2 shown in more detail, the supply tube ( 2 ) of the feeder ( 1 ) a flow straightener ( 5 ). This device ensures a continuous feed to the extruder to minimize or prevent an increase and decrease in feed to the extruder. The device has arms or spokes ( 6 ), which go through the opening of the supply pipe. Most simply, the device may include a lot of crossed wires secured to and through the opening of the delivery tube. Other arrangements of the flow trowel will be apparent to those of ordinary skill in the art. It has been found that the quality of the extruded material, especially the quality of the extruded webs, is substantially improved when using a flow straightener.

The Shape of the tubular extruder injection port determined the shape of the extruded strand, and the shape of the injection port is usually chosen so that the desired Form of the expanded product is prepared. The mixture is usually from the spray opening at a pressure of about 4800 extruded to 13800 kPa (700 to 2000 psi), and the extrudate has when extruding a temperature of about 120 ° C to about 200 ° C. The extruder is usually heated and may have several zones along its length, in which the Temperature is separately adjustable.

To produce injection-molded expanded starch articles, including trays, the extrudate is shaped as a tube using a tubular extruder die orifice. The thickness of the extruded tube is preferably between about 2.5 and 1.27 mm (0.1 to 0.05 inches), and more preferably between about 2.5 to 0.76 mm (0.1 to 0.03 inches ). The extruded tube produced is preferably immediately z. B. compressed by rolling or rolling and stretching between a pair of flat, opposing rollers. The rolling of the tube results in a double folded web. Multiple folded webs can be formed by superposing two or more extruded tubes, followed by compression or rolling. Alternatively, the extruded tube may be split to form a strip which is then compressed or rolled to give a single folded web. The compressed or rolled web is optionally cut and further shaped. For example, a rolled web may be injection molded where it is pressed into the shape of the desired product. The resulting molded article can be finished by smoothing or edging rough edges or by applying desired coatings. For example, sealants, lubricants, water or water repellant coatings can be applied to a desired surface or to minimize the loss of water from (or absorption of excess water by) the molded article. Dyes, fragrances, preservatives, bactericides may also be included in or added to the extrudate, which is used to form the molded article.

Of the Term railway as used herein refers to one in general flat, relatively thin Slab of extrudate which is sufficiently thick to make To allow an expanded article of starch, which holds the size stability. Under The term "web" as used herein is not meant to include linings which do not hold size stability. The method of the present invention can be used around coverings However, webs are the preferred precursors of the molded extruded molded article. Preferred tracks for Production of extruded articles of starch have a thickness, which is bigger than 0.5 mm (1/50 of an inch), and more preferably greater than approximately 1.6 mm (1/16 of an inch). In general, however, the thickness is the web, which is determined in part by selecting the injection port and Type of compressing or stretching used, for example Roll spacing, so chosen that the desired Final dimensions and properties in the molded extruded Article made of starch to be obtained.

It was found to be for the quality of the final poured product beneficial is the ends of the extruded tube before compression or Compress rollers. It is believed that the compression of the pipe end to a Pillow includes steam, during the Compression / rolling is useful to the temperature of the extrudate when compressing / keeping rolling or when compressing / rolling to provide a moist environment. The provision of a steam housing on End of the extruder to trap the extrudate as it passes from the extruder injection port to the extruder Compression led is, for. B. when it is passed through the roller provides an equal advantage for the quality of the compressed or rolled material. It was determined, that the duration between rolling and casting has a significant effect on the quality of the resulting molded article. Preferably the compressed or rolled web is immediately forwarded to the mold for injection molding. An important factor in this step is the temperature of the mold in proportion to the temperature of the web. The web is preferably injection molded, while she is still warm. Alternatively, the mold itself can be heated, a constant quality of the product.

To the extrusion system can during the remaining of the basic starch mixture Added water in the extruder be to the consistency of the starch mixture while to adjust the extrusion and / or the extent of expansion of the product adapt. Lubricant components can also be added to the extrudate added be to the flow through the extruder. Glycerol amounts in the extruder can also be adjusted to improve the flow and / or Properties of the expanded product to vary. It is not required water from the masterbatch in the extruder before the Extrude to remove. In particular, it is not necessary Apply negative pressure to the extrudate to remove water.

With further reference to 1 becomes the extrudate, which the injection orifice ( 7 ) leaves, preferably fed via a roller device ( 10 ) with two or more rollers ( 11 ) disposed in relation to each other to apply pressure to the extrudate substantially perpendicular to the direction of extrusion. Several groups of rolls may be used, arranged one behind the other along the direction of extrusion, to successively apply pressure to the extrudate. Pressure from each roller used is preferably applied substantially perpendicular to the direction of extrusion. Each group of rolls can be adjusted to apply equal or different amounts of pressure to the extrudate. The rolls in a given group of rolls can form an opening corresponding to the shape of the desired product. To form expanded sheets of starch, including those which are optionally subsequently injection molded, one or more pairs of opposing flat rolls may be used. Preferably, the rollers apply sufficient pressure to the strand to substantially compress the cells in the strand, or more preferably to compress the cells. The rolls may also be used to complete molding of the expanded product.

The process of applying pressure to the extrudate, preferably by rolling, is a significant improvement in the manufacturing process of this invention, resulting in substantially reduced brittleness of the extruded starch product. The application of pressure as described herein also reduces the dusting and chipping of the extruded products and increases the bulk density. The roll pressure required to obtain improved properties depends on the shape of the extrudate, the cell size, and bulk density of the extrudate, which in turn depends on the nature of the extrudate depending on the type of starch and contained water. The required roll pressure needed to obtain the desired end properties can be quickly determined empirically for a particular starch composition and product form without needlessly experimenting. Generally, the roller pressure for making web products is higher than for producing shaped loose fillers.

The Roller speed can be adjusted to the extrusion speed essentially to match. If this is the case, only minimal occurs Stretch the extrudate. Alternatively, the roller speed be adjusted to something higher to be the extruding speed. In this case, that will Extrudate both rolled and stretched. Compress in accompaniment of stretching, as applied when an extrudate is rolled and stretched will, surprisingly uncovered that the articles were made of starch using the compressed and elongated extrudates are imparted improved properties. Roller speeds of more than about 50% higher than the extrusion speed can can be used to achieve compression stretches. preferred Roller speeds for stretching and compressing are in between approximately 10% to about 20% higher as the extrusion speed.

3 Fig. 3 schematically illustrates an extruding / rolling / cutting apparatus adapted for producing loose fill products according to the invention. Features that are equal to those 1 are marked with the same reference numbers. Starch, preferably crude, unmodified starch, is mixed with desired additives, for example in a feed apparatus or a mixing chamber ( 1 ), and into an extruder ( 3 ) brought in. In 3 is the Zufuhparparat shown with direct introduction into the extruder. A feeder as in 1 shown with feeding by a flow straightener can also be used. Again, the extruder is preferably a twin-screw extruder as shown schematically ( 12 ). The mixture is further mixed, subjected to shearing, temperature and pressure rise in the extruder to form a mass, preferably a plasticized mass which passes through an expanding spray orifice (Fig. 7 ) is pressed. The extrudate is fed via a roller device ( 10 ) with two or more rollers ( 11 ) which exert pressure on the extrudate, preferably a pressure which is substantially perpendicular to the direction of extrusion. The rollers form an opening according to the shape of the desired product.

The compressed extrudate is cut into desired lengths by a cutting device, for example a rotating knife ( 14 ), which is located behind the rollers. The resulting compressed and cut extrudate is preferably cured under controlled temperature and humidity conditions. The curing is preferably carried out at about 18 ° to about 30 ° C, preferably at 21 ° C, at a humidity in the range of about 40% to about 80%, preferably about 50%, within one to two days.

The Production of expanded loose fillers out of strength and expanded sheets of starch usually become continuously by continuously feeding to the extruder, extruding, Compression / rolling and cutting performed.

One conventional Double-screw extruder with feed screws, single-start guide screws, shear blades (preferably 3 or more, with 3-10 common) and mixing blades (usually 1-5) can used in this method. A worm assembly of expanding type can be used in the twin-screw extruder become. The usual Residence time of the base mixture (ie starch with all additives) in the extruder is about 9 to about 20 seconds and extruding takes place at a speed of about 45 to about 91 kg / h (100 to approx 200 lb / h) per spray opening insert instead of.

The Size and arrangement the spray opening determines the shape of the cross section of the extrudate. A variety of shapes and sizes of final Products can be made. The starch can also be extruded be to webs of cushioning material or for further shaping produce by injection pressure. Usually can Product webs having a thickness of about 2.5 to about 6.4 mm (1/10 to about 1/4 inch) by the extrusion / compression process become. Shaped products made of starch for loses Packaging material can for example, have several cross-sectional shapes, including, under other, the big one Omikrons, the number 8, short rods, S-shaped, C-shaped, oval and an omega. The product form has no significant effect on the elasticity of loose Füllverpackungsmaterial. The volume density of loose filler however, it may depend on the shape.

A variety of shapes and sizes of loose end fill products can be made by changing the shape of the injection port. Various roller arrangements can be used in the production of loose filling material. 4a introduces the use of two counter-rotating rollers ( 21a and 21b ) in combination with a spray opening ( 7a ) to loose filling material (a) in the form of a number 8th to build. The designed roller arrangement is shown separately. 4b represents a 3-roll arrangement ( 22a . 22b and 22c ) to form a product with a triangular cross-section. The direction of extrusion through the rollers is indicated by arrow 19 shown. 4c represents a second 3-roll arrangement ( 23a . 23b and 24 ) to form a product in the form of an omega. 4d and 4e represent two different 4-roll arrangements ( 25a -D or 26a -D), which results in products with concave or convex sides. Many other roll arrangements, including flat, corrugated, or otherwise shaped rolls, can be used to obtain the desired shape of loose fill product. In each of the illustrations 4 the roll spindles and the rolling direction are indicated.

at a preferred roller device will put pressure on the extrudate applied substantially perpendicular to the extrusion direction. The Warm extrudate can easily pass through the opposing flat rollers (which from the spray opening can discard the given form) guided become. In general, it is preferred that the roll or rolls Pressure symmetrical to the warm extrudate according to the desired Apply product form, eg. For example, a rolled sheet is preferable for injection molding of bowls and the like containers used. Rollers can made of stainless steel, Teflon or related materials which are opposite to the extrudate are inert. The rollers are preferably so in view of Extruder die arranged that the warm extrudate be fed directly to the rollers can, as long as the extrudate is still warm.

One Step of compression or rolling was not previously at the Production of expanded products from starch applied. preferred Rollers are provided with a spring and the applied pressure is adjustable. While Roll the preferred method of applying pressure to the Extrudate is to desired Achieving properties in expanded items from strength is the It will be apparent to those of ordinary skill in the art that other methods are used can be to the desired To achieve the result. It becomes obvious that a variety of procedures available is to stretch the extrudate. In particular, a variety to methods of stretching the extrudate before, during or after compression available.

Preferably, the rolls are placed sufficiently close to the extruder injection port that the extrudate remains warm during rolling. For ease of illustration, the roller device shows 1 a group of rollers. Two or more groups of rolls in series may be used in the processing method according to the present invention. The use of more than one group of rolls can improve the efficiency of the process. It should be noted, however, that the extrudate remains warm during the rolling process. The rollers can be heated. In particular, for the production of webs of starch, the use of two or more rolls may be preferred in order to obtain the desired final properties.

The Shape of loose filling packaging materials affects the ability of the material, to interlock. Loose filling material, which is shaped like this is that the pieces meshing is less easy to push through impact and protects The packaged items better from damage by shocks. Preferred forms for loses filling material with the ability interlocking are those with protrusions and indentations, which it's pieces enable, mate.

The preferred extruder feed compositions of the present invention Include raw, unmodified starch as the main ingredient (about 70% to approximately 97% by weight). Lower amounts of additives, including lubricants, Plasticizer, humectant, nucleating agent and a other propellant (in addition to water), with the additives preferably up to a maximum of 30% by weight of the total weight of the extrudate added become. One of the preferred extrudates contains a minimal amount of plasticizers, including Polyvinyl alcohol or ethylene vinyl alcohol (or other polyols), to the desired Properties obtained by the improved extrusion / compression process, which is described here, is processed. In particular, includes preferred extruder feed less than about 5% by weight polyvinyl alcohol or ethylene vinyl alcohol. Even more preferred extruder feeds include less than or equal to about 2.5% by weight or less than or equal to about 1% after Weight of polyvinyl alcohol or ethylene vinyl alcohol.

water The extruder feed is usually while their passage through the extruder is added, usually at the inlet area of the extruder. In addition Gefügtes Water can generally be about 30% or less of the starch composition in the extruder. additionally are changeable Amounts of water in the starch even available. The amount of added water in a given Extrusion hangs from the extruding conditions, the initial water content of the used Strength and the desired one Product off. In general, the amount of water in the extrudate adjusted to maximize the stretch of the extruded product, being a soft or too liquid Extrudate is avoided. Water can with other components of the Basic starch mixture be premixed or added separately from them. For example, water may be added to the extruder through inlet ports and adding adapted and controlled. The amount of added water depends on the moisture content of the raw starch. The total water content the basic starch mixture before extruding is usually between about 6% and about 18%.

It It was found that injection-molded articles with suitable Properties for Packaging applications, such as containers and trays, using can be made of extruder feed compositions which no polymeric or polyol plasticizer, for example no PVA or EVA.

In preferred embodiments this invention uses crude, unmodified, non-derivatized starch, which is essentially strength is, as it occurs in nature, other than those that are physical is separated from other plant components. The strength is common a powder (fine or coarse) or granules. Corn starch is The preferred starch in the present invention, however, may be any type of unmodified starch Wheat, rice, potatoes, tapioca or the like, or mixtures of Strengthen be used. Mixtures of starches from different plant sources can be used. additionally can other natural or synthetic materials having starch as a main component, for example, rice flour, also as a source of starch for the process according to the present Invention can be used.

The Invention does not require the use of high amylose starch the desired good flexibility or elasticity to obtain. The invention does not require the use of derivatized Strength, like for example, starch, which at the hydroxy group changed by chemical reaction (eg esterified, etherified or phosphorylated). The invention does not require pretreatment of starch by treatment with heat or Pressure, gelatinization or destructuring of starch Add to the extruder. Nevertheless, starch compositions can be used High amylose starch, have modified or derivatized starch, or pretreated, gelatinized or destructured starch compositions the improved extrusion, compression and stretching method of the present invention Be processed to improve extruded materials with To provide properties for use as packaging materials. Mixtures of modified or otherwise treated starch and raw, unmodified starch can used in the process of the present invention. to Use in the present invention is preferred starch predominantly unmodified starch, d. H. Strength, which contains 50% or more by weight of unmodified starch.

flexible, supple and elastic expanded products of strength of present invention be prepared with lower amounts of plasticizers, in particular polyvinyl alcohol, ethylene vinyl alcohol and related polyol materials, as taught in the prior art.

The premixed basic starch mixture, the extruder feed (including any added Water, lubricant, glycerin or other ingredients) be introduced directly into the extruder, or the individual components can be added in any order to the extruder, to be mixed in it. In a preferred method of adding The ingredients include water, lubricant and glycerin added by remaining ingredients in the extruder independently adjustable inlets in the extruder. Extruder feed mixtures The present invention mainly comprises starch with small amounts of nucleating agent, such as cornmeal or talc.

The preferred extruder feed mixture of the present invention mainly comprises starch with small amounts of humectants, plasticizers, lubricants, nucleating agents, and optionally blowing agents and agents which function to reduce cell size. Glycerol, related polyols including pentaerythritol and vegetable oil can act, inter alia, in extruding the starch as a humectant and / or lubricant to ver the flow properties of the mixture ver improve and provide smooth surfaces for extrusion. Polyvinyl alcohol, ethylene vinyl alcohol and related polymeric polyols can act as plasticizers. Glycerin can also act as a plasticizer. Talc, protein such as cornmeal, in egg albumin or blood meal or other protein sources, and materials which produce CO ₂ -like "hydrocerol" (trademark, Boehringer Ingelheim) may act as nucleating agents.

For example, encapsulated sodium bicarbonate and citric acid mixtures, "hydrocerol" which produces CO ₂ , and sodium citrate (CF and BIH forms, available, for example, from Boehringer Ingelheim) may act as a nucleating agent. Various forms of encapsulated materials are available in which the encapsulated ingredients are released at different temperatures. One of ordinary skill in the art can quickly choose the appropriate shape for a given application. In general, the shape that results at the lowest temperature that matches the application is used. Glycerol monostearate and other glycerol monoesters of fatty acids, for example "myvaplex", can act as an aid in the formation of uniform small cells in the extruded material. Superheated water in the extrudate can serve as a propellant. The extruder feed of the present invention may also contain additional minor amounts of blowing agents, including, among others, carbonate salts including sodium, potassium and ammonium salts. Any vegetable oils or polyols used in the masterbatch are preferably pumpable. In general, the extruder feed mixture of the present invention may contain compositions of one or more humectants, plasticizers, lubricants, nucleating agents, and / or propellants. The maximum amount of these additives is preferably about 30% by weight of the total weight of the extruder feed mixture (including added water). The extruder feed mixture preferably contains a minimum of these additives required to obtain the desired properties of the extruded product. The mixture contains a minimal amount of plasticizers to reduce their costs.

Of the The compression / rolling step of the present invention enables the Use of significantly lower amounts of plasticizers than in prior art processes are required to form flexible, non-brittle expanded products made of starch to obtain. A preferred extruder feed contains less as about 5% plasticizer. Polymeric vinyl alcohols are often used in starch extrusion processes Softener used. The preferred extruder feed mixtures of the present invention contain less than about 5% after Weight of polyvinyl alcohol, polyethylene alcohol or related polymers Vinyl alcohols (or mixtures thereof). Preferred extruder feed mixtures of the present invention include those in which the amount polymeric vinyl alcohol is less than about 5% by weight, and especially those with about 2.5% by weight and those with less than about 1% after Weight of polymeric vinyl alcohol. PVA with different molecular weights is available. Airol 325 and Airol 540, both available from Air Products as extruder feeds for found the present invention to be suitable. mixtures of the present invention also relatively small amounts than glycerine or other humectants contain.

mixtures of the present invention include those in which the glycerol content less than about 1.5% by weight, and those in which the glycerine content is lower is as about 0.5% by weight. Mixtures of the present invention include also those in which the talc content is between about 1% after Weight and about 10% by weight, and those in which the talc content is between approximately 1% by weight and about 5% by weight.

glycerol (for example, "Myvaplex" (trademark, Eastman Kodak) may be included in the extruder feed to improve Uniformity of cell size in the expanded strength to deliver. Glycerol monostearate is preferably present in the extruder feed in an amount in the range of about 0.1% to about 0.5% by weight. More preferably, it is in an amount of about 0.15 to about 0.25% available by weight.

To the Example may be the extruder feed mixture of the present invention contain the following ingredients, expressed in weight percent: starch (about 70 to approximately 97%), preferably mainly raw, unmodified starch; add gefügtes Water (up to about 30%); vegetable oil (up to about 6%); Glycerin (up to about 3%); Polyvinyl alcohol or other plasticizers (up to about 25%, preferred Maximum of less than 5%); proteinaceous cereal flour (up to about 20%); Glycerol monostearate (up to about 0.5%); additional Propellant (up to about 0.8%); and talc (up to about 10%) on the condition that the mixture is a nucleating agent must contain. extra Water and / or lubricants can while added to the extruding become.

Other examples for Extruder feed blends suitable for use in the present invention include the following, the composition being in weight percent expressed is:

Composition A points on:

• Strength approximately 60% to about 70%;
• proteinaceous Cornmeal 0% to about 10%, if present, preferably about 4% to about 10%;
• Polyvinyl alcohol 0% to about 27%, if present, preferably less than about 5%;
• Talk 0% to about 20%, if present, preferably about 0.1% to about 10%, more preferably approximately 0.1% to about 1.5%;
• "Myvaplex" (glycerol monostearate) 0% to about 0.5%, if present, preferably about 0.1% to about 0.3%, more preferably approximately 0.2%; and
• "Hydrocerol" 0% to about 2%, if present, preferably approximately 0.2% to about 0.5%;
• on the condition that a nucleating agent exists have to be;

Composition B points on:

• Strength approximately 70% to about 97%;
• proteinaceous Cereal flour preferably about 4% to about 10%;
• Polyvinyl alcohol 0% or, if present, preferably less as about 5%, more preferably less than about 2.5%, or less than about 1%;
• Talc 0% or, if present, preferably about 0.1% until about 1.5%;
• "Myvaplex" about 0.2%; and
• "Hydrocerol" 0% or, if present, preferably about 0.2% to about 0.5%;

Composition C points on:

• Strength approximately 70% to about 97%;
• proteinaceous Cornmeal 0% or, if available, preferably about 4% to approximately 10%;
• Polyvinyl alcohol, preferably less than about 5%, still more preferably less than about 2.5% or less than about 1%;
• Talk preferably about 0.1% to about 1.5%;
• "Myvaplex" about 0.2%; and
• "Hydrocerol" preferably about 0.2% until about 0.5%

Composition D points on:

• Strength approximately 70% to about 97%;
• proteinaceous Cornmeal 0% or, if available, preferably about 4% to approximately 10%;
• Polyvinyl alcohol, preferably less than about 5%, still more preferably less than about 2.5% or less than about 1%;
• Talk preferably about 0.1% to about 10%;
• "Myvaplex" about 0.2%; and
• "Hydrocerol" 0% or, if present, preferably about 0.2% to about 0.5%;

Composition E points on:

• Strength approximately 70% to about 97%;
• Polyvinyl alcohol, preferably less than about 5%, still more preferably less than about 2.5% or less than about 1%;
• Talk preferably about 0.1% to about 10%, more preferably about 1% to about 10%;
• "Myvaplex" about 0.2%; and
• "Hydrocerol" 0% or, if present, preferably about 0.2% to about 0.5%;

Composition F points on:

• Strength approximately 70% to about 97%;
• Polyvinyl alcohol, preferably less than about 5%, still more preferably less than about 2.5% or less than about 1%;
• Talk preferably about 0.1% to about 10%, more preferably about 1% to about 10%; and
• "Myvaplex" about 0.2%;

Composition G points on:

• Strength approximately 70% to about 97%;
• Talk preferably about 1% to about 10%, more preferably about 5% to about 6%; and
• "Myvaplex" about 0.2%; and
• "Hydrocerol" preferably about 0.2% until about 0.5%;

Composition H points on:

• Strength approximately 70% to about 97%;
• Polyvinyl alcohol, preferably less than about 5%, still more preferably less than about 2.5% or less than about 1%;
• "Myvaplex" about 0.2%; and
• "Hydrocerol" preferably about 0.2% until about 0.5%;

Composition I points on:

• Strength approximately 60% to about 97%;
• proteinaceous Cereal flour preferably about 4% to about 10%;
• Polyvinyl alcohol up to about 27%;
• "Myvaplex" about 0.2%;
• Oil, z. Vegetable oil, 0% to about 1.5%;
• Glycerol 0% to about 1.5%; and
• "Hydrocerol" preferably about 0.2% until about 1%;

The Extruder feed composition of the present invention may optional dyes, fragrances, bactericides and mold inhibitors contain. The extruder feeder Optionally different fiber sources, for example soy fiber, contain. The fiber content is preferably in the range of to at 10% by weight of the extruder feed, but can change be to the stiffness of extruded webs and molded articles adapt.

It it was found that starch materials, which were compressed into webs and injection molded in the extrusion process can be reused by very fine grinding of the materials and combining them with additional Feed composition. For example, it has been found that the use of a Extruder feed in which up to about 20% by weight of starch was reused ground extruded starch is, no significant deterioration in the properties of the final extruded, resulting in a shaped product. Depending on the desired Final properties of the product may be a higher or lower percentage on reused material in the extruder feed for processing includes his.

Elasticity (also Volume elasticity called) is the ability a material, its size and shape restore, d. H. after deformation by a compression force to restore its original volume. Volume elasticity of a Material is evaluated as a percentage restoration of volume by measuring the original one Volume (as height a given amount of material in a container) and volume after a recovery time of about 30 seconds after applying a compression force. The loose filling products, which have been prepared as described herein generally an elasticity of about 50% or more up. Preferred loose filling products have an elasticity of more as about 60%, and more preferred loose fill products have an elasticity of about 75% or more on. The most preferred loose fillers exhibit elasticity between approximately 85% and about 95% up. In the present invention, the molded expanded Products a high elasticity essentially imparted by the physical process step compressing, rolling or preferably by rolling with stretching of the warm extruded product. The small amounts of humectants and plasticizers that are in the basic starch blend are not themselves contributing to the essential improvements the elasticity at.

Packaging materials may also be based on their volume density (weight / unit volume) and volume compressibility (ie, the maximum force required to place the sample on a be compared and evaluated for the selected% of their original volume, usually to 2/3 of their original volume). Flexibility, the ability to bend without breaking, can be qualitatively evaluated by compression by applying pressure by hand to the final extruded and molded products to evaluate how much force can be applied before the extruded product breaks.

Compressed or rolled extrudates of the present invention may have a bulk density of less than about 32.0 kg / m ³ (2.0 lbs / ft ^3), but greater than 4.0 kg / m ³ (0.25 lbs / ft ³ ) exhibit. The typical bulk density for corn starch products according to the present invention is about 8.0 to 12.8 kg / m ³ (0.5 to 0.8 lbs / ft ³ ). The material after extrusion is usually much lighter than the final product because compression or rolling increases the bulk density. Expanded products of starch have a moisture content that is generally lower than that of the extruder feed material. Typically, the compressed / rolled expanded products will contain from about 5% to about 9% by weight moisture, and more usually from 6% to about 7% by weight moisture.

The mechanical properties of injection molded and other expanded Articles made of starch, produced by the method of the present invention, can be judged, for example, by making stretchy and Izod strips according to the ASTM test method, D638-84 and D256-84.

The extruded expanded starch products according to the present invention are useful in applications of molded articles as packaging materials. additionally to loose filling packaging materials can Tracks of strength for wrapping or other applications by the extrusion rolling method of the present invention Invention are produced. In particular, webs of starch, the prepared by the method described herein, with Paper and other biodegradable materials combined to give biodegradable coated materials, like envelopes. Furthermore you can Articles containing a variety of shapes including bowls and other containers have to be produced by the method described here in Combination with conventional Method of casting, in particular injection molding, of expanded strength.

The The following examples represent the basis of the invention Principles

EXAMPLES:

Example 1: Preparation of injection molded expanded starch products

extruded Tracks of strength, the injection molding of shells and other shaped articles with low brittleness, suitable flexibility and useful dimensional stability were prepared using the extrusion compression method of the present invention, exemplified by using rollers to compress the warm extrudate. Extruder feed compositions useful in this process include compositions A-I as described above.

The Components of the feed mixture were added before being introduced into mixed the extruder. Water was added independently to the extruder. Of the Extruder used is a Wenger Model TX52 twin-screw extruder (Wenger Manufacturing, Inc. Sabetha, Kansas), which uses feed screws, catchy Leitschnecke, 5 shear blades and 10 mixing blades was adjusted. The cylinder of the extruder has three temperature zones. The mixture is plasticized in the extruder. In general, the extruder conditions Set as known in the art to a soft flow to deliver the extrudate. More details are given below.

screw devices

screw devices the type standard (# 1), high performance (# 2) or medium power (# 3) were suitable for extrusion.

Experimental conditions for the extrusion are:
Worm assembly # 1 has the following characteristics 4 ea 1.5D ¾ slope 10 ea double-start shear @ 45 ° 4 ea 1.5D ¾ slope 5 ea double-start shear @ 45 ° 1 ea 376 conical snails

Worm assembly # 2 has the following characteristics 4 ea 1.5D ¾ slope 10 ea double-start shear @ 45 ° 2 ea 1.5D ¾ slope 1 ea 1.5D ½ slope (shortened flightwalk) 1 sentence ring-shaped shears, 6.5 mm thick (36/52 OD) 1 sentence annular shear barriers, 6.5 mm thick (42/47 OD) 8 ea double-start shear @ 45 ° 1 sentence ring-shaped shears, 13 mm thick (36/52 OD) 1 ea 387 conical snails

Worm assembly # 3 has the following characteristics 4 ea 1.5D ¾ slope 10 ea double-start shear @ 45 ° 2 ea double-edged shear (thin) 3 ea 1.5D ¾ slope 1 sentence annular shear barriers, 6.5 mm thick (42/47 OD) 8 ea double-start shear @ 45 ° 1 sentence ring-shaped shears, 13 mm thick (36/52 OD) 1 ea 387 conical snails

Passage 1

The extruder feed (in weight percent) used was: crude, unmodified corn starch 92.1%; PVA (Airvol 540) (Air Products) 2.4%; Talc 5.1%; "Myvaplex" 0.2% and hydrocerol BIH 0.3%.

Experimental conditions for the extrusion are:
Worm Assembly # 1, Worm 474 RPM Annular Slot Nozzle (Arrangement Dwg 2979025A (BEI), Nozzle with Adaptable Outboard Nozzle Body, Nozzle Body # 2979025A, Screw # 2979022A, Nip 0.203 mm, Roller Speed 28 rpm (approximately the feed rate to the extruder (ie, extruding speed)). Feed rate 28.6 kg / hr (63 lb / hr). Temperatures (° C) Z4 180 ° Z3 100 ° Z2 70 ° Z1 120 ° Water addition 95 g / min (0.21 lb / min)
specific mechanical energy 0.099

The Roller speed was set, the feed rate approximately to match, so that the webs rolled but not stretched were. Rolling improved web quality and made it more uniform Moisture content over the train sure. Increased flexibility through rolling was evident. Good quality bowls (flexible with size stability) were made in this passage.

Passage 2

The extruder feed (in weight percent) used was: raw, unmodified cornstarch 94.3%; Talc 5.2%; "Myvaplex" 0.2% and Hydrocerol BIH 0.3%; a feed containing no PVA The extruder conditions were: S
worm assembly # 1, screw 500 rpm. Same spray opening as in passage 1. Nip 0,203 mm. Roller speed 17 rpm. Feed rate 28.6 kg / h (63 lb / h). Temperatures (° C) Z4 180 ° Z3 100 ° Z2 70 ° Z1 136 ° Water addition 0.113 kg / min (0.25 lb / min)
specific mechanical energy 0.087

Under Using this method, trays were of excellent quality produced.

Passage 3

In this run, the same feed was used as in Run 1 and the pass served to assess the use of a higher feed rate and higher screw performance. The bowls produced were of excellent quality and no significant difference could be detected by changing the parameters. Extruder conditions:
Worm assembly # 2, screw 480 rpm. Same injection opening as in passage 1. nip 0.203 mm. Roll speed 17 rpm (web rolled and stretched). Feed rate 33 kg / h (72.83 lb / h). Temperatures (° C) Z4 180 ° Z3 100 ° Z2 70 ° Z1 153 ° Water addition 0.145 kg / min (0.32 lb / min)
specific mechanical energy 0,11

Passage 4

Recycled extruded web (approximately 10% by weight of the total extrudate) was used in this run. The extruder feed used (in weight percent) was: total starch 92.1% (raw, unmodified cornstarch plus recycled extruded sheet of starch prepared using the formula from Run 1 above); PVA 2.4%; Talc 5.1%; "Myvaplex" 0.2% and Hydrocerol BIH 0.3%. The recycled extruded web is the remainder from previous extruder trial runs. The recycled materials were first flocculated in a flake machine and then ground three times in a Fitz mill to a fine consistency. The milled material was mixed with fresh material in a ribbon blender; mixing time is standard, about 15 min. The trays made from the feeder, which contained reused extruded webs, were supple and felt silky. Extruder conditions:
Screw arrangement # 1, screw 500 rpm. Same injection opening as in passage 1. nip 0.203 mm. Roller speed 24 rpm (increasingly the same as increasing the feed rate). Feed rate 28.6 kg / h (63 lb / h). (Increase to 45.8 kg / h (101 lb / h).) Temperatures (° C) Z4 180 ° Z3 100 ° Z2 70 ° Z1 127 ° Water addition 0.113 kg / min (0.25 lb / min)
specific mechanical energy 0.099

Example 2: Preparation of loose stuffing material

A loose fill wrap material having high suppleness (about 85% to about 95%) in the form of a stick is prepared using a master mix containing the following ingredients listed in weight percent: % by weight unmodified corn starch 77.7 water 2.8 vegetable oil 0.97 glycerin 1.6 polyvinyl alcohol 4.9 cornmeal 9.7 "Myvaplex" (brand, Eastman Kodak, 0.39 Monoglyceride of stearic acid, ie glycerol) talc 1.9

The used corn starch points approximately 22% by weight of amylose and about 8% to about 15% water by weight. The used polyvinyl alcohol has a molecular weight in the range of 200,000 to 300,000.

These Ingredients, except water, vegetable oil and glycerin, were present mixed with the introduction into the extruder. Water, vegetable oil and glycerin became independent added to the extruder through separate inlets. Of the Extruder used was a Wenger Model TX52 twin-screw extruder (Wenger Manufacturing, Inc. Sabetha, Kansas), which with feed screws, catchy Guide screws, 5 shear blades, 10 mixing blades and one injection port inlet with a diameter of 2.54 mm (100 mil) was adjusted to a rod-shaped Produce extrudate. The barrel of the extruder has three temperature zones (150 Z6 [actual Temperature 144 ° C], 90 Z5 [actual Temperature 139 ° C] and 70 Z4 [actual Temperature not measured]). The screw turned at 495 rpm. The plasticized mass was at a rate of 50 kg / h (110 lb / hr) at 6900 kPa (1000 psi), and the extrudate had a temperature of about 175 ° C. The Dwell time of the material in the extruder was about 13 seconds.

The extruded material was rolled perpendicular to the direction of extrusion, to substantially compress the cells therein. To the rolling subsequently For example, the strand may be divided into narrow segments of approximately equal length (approximately 25.4 inches) mm (one inch) length) get cut. The expanded, rolled and cut Products were at 21 ° C cured in a 50% humidity environment for 24 h. The cured Product showed excellent elasticity and wear resistance on.

Example 3: Coated "Kraft" (brand) paper for packaging applications

A Base mixture of this invention is introduced into an extruder, such as for example, the twin-screw extruder as described in Example 1, adapted with a flat or slot-shaped injection opening, to form the extruded webs. The extruded sheets will be rolled by rolling, preferably two groups of flat rolls, which pressure perpendicular to the direction of extrusion and perpendicular to the plane exercise the track. The one exercised on the track Pressure was sufficient to compress the cells in the lane substantially. The rolled sheet is, if desired, collected by rolling on a roll and along its width cut to the desired ones track lengths to build. The rolled sheet is allowed to set at about room temperature medium humidity (approx 40-60%) hardened.

The The resulting supple web of starch can be used directly for packaging applications or may be used in layered packaging products become. Coated packaging products include, among others, "Kraft" paper, which coated with a supple sheet of starch.

"Kraft" paper comes with Water moistens, a correspondingly large sheet of starch is moistened over the water Paper is arranged and the paper and the web are made of starch rolled to ensure that the two layers are completely together are in contact and adhere. Additional layers of paper or from tracks of strength can added by the same steps to obtain a coated multi-layer material. "Kraft" paper with a single layer (approx 2.5 mm to about 6.4 mm (1/10 to about 1/4 inch) thick) of a sheet of starch can be used around padded envelopes or other letterbox manufacture.

Claims (28)

A continuous process for making an expanded starch shaped article comprising the step of: (a) introducing an extruder feed composition comprising from 70% to 97% by weight of starch into an extruder; characterized in that the method further comprises: (b) extruding the composition through a tubular injection port to produce a tubing extrudate; (c) stretching the tubing extrudate as it exits the tubular syringe port; (d) substantially compressing the tubing extrudate to form a sheet of extrudate; and (e) forming the sheet of extrudate to form a shaped article. The method of claim 1, wherein the tubing extrudate is stretched by pulling it from the tubular injection opening a speed faster than the speed of extrusion. The method of claim 1 or 2, wherein the Tube extrudate is stretched at a ratio of up to 1.5. A method according to claim 1, 2 or 3, wherein the tube extrudate is stretched at a ratio in the Range from 1.1 to 1.2. The method of claim 1, wherein the web comprises Extrudate is introduced into a printing plate and then the web is formed from extrudate to form a molded article. Method according to one of the preceding claims, in which the tube extrudate is substantially compressed by performing the Extrudates through a group of rollers to make the web of extrudate to build. Method according to one of the preceding claims, in which the tube extrudate is substantially compressed by performing the Tubing extrudate through at least one group of rollers, and wherein the Rolled extrudate is further stretched before, after or during the rolled extrudate is compressed. Method according to one of the preceding claims, in which the tube extrudate is substantially compressed while the Extrudate is hot. Method according to one of the preceding claims, in which further includes the extruder feed composition less than 5% by weight of a polymer plasticizer. Method according to one of the preceding claims, in which further includes the extruder feed composition less than 2.5% by weight of a polymer plasticizer. Method according to one of the preceding claims 9 and 10, in which the polymer plasticizer is a polyvinyl alcohol. Method according to one of the preceding claims 9 and 10 wherein the polymer plasticizer is ethylene vinyl alcohol. Method according to one of the preceding claims, in which further includes the extruder feed composition less than 10% by weight of a nucleating agent. Method according to one of the preceding claims, in which further includes the extruder feed composition less than 5% by weight of a nucleating agent. Method according to one of the preceding claims 13 or 14, in which the nucleating agent is proteinaceous cereal flour. A method according to any preceding claim 13 or 14, wherein the nucleating agent is talc is. Method according to one of the preceding claims, in which further includes the extruder feed composition a lubricant. Method according to one of the preceding claims, in which further includes the extruder feed composition a humectant. Method according to one of the preceding claims, in which further includes the extruder feed composition a propellant. The method of claim 19, wherein the extruder composition further comprises less than 1.5% by weight of a blowing agent. Method according to one of the preceding claims, in which the extruder feed composition is a or several different types of starch. Method according to one of the preceding claims, in which the strength includes an unmodified starch. Method according to one of the preceding claims, in which reprocessed the extruder feed composition expanded compressed strength includes. Method according to one of the preceding claims, in which the strength 20% by weight or less in the extruder feed composition expanded compressed strength is. Method according to one of the preceding claims, in which the strength recycled in the extruder feed composition 10 wt .-% or less expanded compressed strength is. Method according to one of the preceding claims, in which further includes the extruder feed composition Glycerol monostearate. Method according to one of the preceding claims, in which comprises the extruder composition rice flour. Method according to one of the preceding claims, in which the article is a cup.