Patent Abstract:
Disposable, thin-walled molded articles, such as cups, plates, fast-food packages, trays, flat sheets and the like are produced by applying a starch-based baking composition onto the lower mold part of a multi-part, preferably two-part mold, and by baking and conditioning the composition to a moisture content of between 6 and 22% by weight. The baking composition, in addition to water and a starch or starch mixtures and/or flour or flour mixtures and/or starch derivatives, contains a fat-free or oil-free release agent and, optionally, other typical additives. Polyvinyl alcohol is added to the baking mixture in quantities of 0.5 to 40% by weight, relative to the starch component. The polyvinyl alcohol has a degree of polymerization of over 1000, preferably over 1600 and in particular over 2000, and the proportion of water is 100 to 360% by weight, relative to the starch component. Polyvinyl alcohol can be added either in dry form or in the form of an aqueous solution.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of international application PCT/AT96/00107, filed Jun. 14, 1996 which designated the United States. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a method for producing disposable, thin-walled molded articles, such as cups, plates, fast-food packages, trays, flat sheets and the like by applying a starch-based baking composition onto the lower mold part of a multi-part, preferably two-part mold, baking and conditioning to a moisture content of 6% by weight to 22% by weight, the baking composition, in addition to water and a starch or starch mixtures and/or flour or flour mixtures and/or starch derivatives, contains a release agent, namely one or more medium- or long-chained, optionally substituted fatty acids and/or salts thereof and/or acid derivatives thereof, such as acid amides, and/or a polymethyl hydrogen siloxanes, and optionally: 
     thickening agents, such as swelling starch, pregelatized starch or baking waste, and/or guar flour, pectin, carob seed flour, carboxymethylcellulose and/or gum arabic; 
     fibrous materials, such as cellulose-rich raw materials, plant materials, fibers of plastic, glass, metal and carbon materials; 
     nonfibrous filler materials, such as calcium carbonate, coal, talcum, titanium dioxide, silica gel, aluminum oxide, shellac, soy protein, powdered wheat gluten, powdered egg white from chicken eggs, powdered casein; 
     powdered pigments; 
     a zirconium salt, preferably ammonium zirconium carbonate and/or ammonium zirconium acetate, as structural stabilizers; 
     preservatives and antioxidants. 
     Molded articles produced with these prior art baking compositions still have a number of disadvantages. For instance, at relatively low humidity, approximately below 50%, in conjunction with slow moisture desorption, these molded articles exhibit ever-increasing brittleness. 
     This makes itself felt especially disadvantageously in two areas: 
     1. Over the course of long-term storage and in heated rooms during the winter, the relative humidity is often below 20%, or even below 10%. 
     2. In molded articles or molded article parts that are exposed to increasing bending strain: as an example, drinking glasses (compression strain during use) or two-piece hinged molded articles (&#34;clamshells&#34;), where the hinge is likely subjected to repeated opening and closing operations (requiring increased flexibility). 
     Another disadvantage of molded articles of starch, precisely in comparison with cellulose-based materials (paper, cardboard) is the virtually complete loss of tear strength if they become soaked. 
     Polyvinyl alcohol is a biodegradable synthetic polymer that has long been used for water-soluble films, in paper processing, and in textile impregnation. Its use together with types of starch is known from the production of cast films and from extrusion technology. 
     U.S. Pat. No. 3,312,641 to Young teaches that films cast from aqueous solution and comprising amylose or amylose-rich starch and polyvinyl alcohol, have greater tensile strength and are more stretchable, at 23 and 50% relative humidity, than pure starch films. 
     U.S. Pat. No. 3,949,145 to Otey describes similar improvements in sheets made of normal cornstarch (27% amylose), used jointly with formaldehyde for cross-linking. 
     U.S. Pat. No. 5,095,054 to Lay et al. and European Patent Application EP 0 400 531 A1 (Bastioli et al.) describe the melt extrusion of starch, water and polyvinyl alcohol to form a homogeneous melt. These references state that improved dimensional stability at high humidity is found. 
     According to U.S. Pat. No. 4,863,655 to Lacourse, a homogeneous melt of amylose-rich starches, water and up to 10% polyvinyl alcohol is again extruded. The result obtained is an expanded foam (filler chips). 
     Methods for producing foamed molded articles of starch from baking compositions by gelatinization without creating homogeneous melts beforehand are known from U.S. Pat. No. 5,376,320 to Tiefenbacher et al. (corresp. European Patent Disclosure EP 513 106 B1). 
     A decrease in brittleness at relatively low humidity and an increase in flexibility and water resistance of such molded articles with starch is desirable and could greatly expand their fields of application. 
     However, the art has had reservations with regard to the well-known adhesive action of polyvinyl alcohol. 
     In a baking method at temperatures of around 200° C., the question of thermal stability and formation of residues on the hot mold surfaces must also be taken into account. 
     Not least because of the known rheological properties of the starch--&#34;dilatory&#34; viscous behavior with the danger of seizing of pumps from friction at high viscosity, for instance--the use of high-viscosity additives, such as polyvinyl alcohol, appears inadvisable. On the other hand, with major dilution with water in this process technique and an attendant decrease in the proportion of dry substance and increase in the water &#34;leavening&#34; in the baking compositions, it is known that only lightweight, fragile molded parts, and in some cases only molded parts that are not cohesive, or parts that foam markedly out of the mold can now be produced. 
     Surprisingly, it has now been discovered that most of these prejudices are unjustified, as long as certain factors, described in further detail below, are taken into account. 
     SUMMARY OF THE INVENTION 
     It is accordingly an object of the invention to provide a method for producing disposable thin-walled molded articles, which overcomes the above-mentioned disadvantages of the heretofore-known devices and methods of this general type. 
     With the foregoing and other objects in view there is provided, in accordance with the invention, a method for producing disposable, thin-walled molded articles, which comprises: 
     providing a multi-part mold, preferably a two-part mold with a lower mold member; 
     preparing a starch-based baking composition with a starch component selected from the group consisting of starch, starch mixtures, flour, flour mixtures, and starch derivatives; adding water at a proportion of 100 to 360% by weight, relative to the starch component, and a mold release agent; 
     adding polyvinyl alcohol in quantities of 0.5 to 40% by weight, relative to the starch component, to the baking composition, wherein the polyvinyl alcohol has a degree of polymerization of over 1000; 
     feeding the starch-based baking composition into the lower mold member; and baking and conditioning the baking composition to an initial moisture content of about 2-4% by weight. Thereafter, the moisture content of the composition if allowed to equilibrate with the moisture in the ambient to a level of about 6-22%, and preferably to a level of about 7-12%. Maintaining the moisture content within these limits is important to the strength characteristics of the products of the invention. 
     The expression &#34;thin-walled material&#34; as used herein is intended to mean that the thickness of the material from which the article of manufacture is shaped is at least about one to two orders of magnitude less that the size of the article itself. For example, the drinking cups, plates, fast-food packages, etc. contemplated herein typically have a wall thickness on the order of about 0.5-3 mm as compared to an overall dimension of the article on the order of about 50-300 mm. 
     Products with improved flexibility, increased water resistance and better compatibility and hence adhesion for hydrophobic cover layers are obtained if polyvinyl alcohol in quantities of 0.5 to 40% by weight, relative to starch mass, is added to the baking mixture, if the polyvinyl alcohol has a degree of polymerization of over 1000, preferably over 1600 and in particular over 2000, and if the proportion of water is 100 to 360% by weight, relative to starch products. 
     The products produced by the method of the invention have the following features of interest, particularly with a view to process technology: 
     1. After baking, the products do not adhere to the baking molds, even though polyvinyl alcohol is a known hot-melt adhesive and softens above its glass transition temperature of about 80° C. This might be ascribed to the fact that polyvinyl alcohol, on heating and drying at high temperatures (below the melting point, which depending on the type, is between 185 and 230° C.), crystallizes rapidly. 
     X-ray diffraction analyses for molded articles of pure starch exhibit an amorphous diffraction pattern, while in the presence of polyvinyl alcohol, crystalline structures are found. 
     This crystallinity is also a kind of physical cross-linking, by which the absorption of water and the attendant structural softening are reduced. 
     In contrast, extruded starch and polyvinyl alcohol foams exhibit less crystallinity, since there is no opportunity for agglomeration in the production process. 
     2. The &#34;baked&#34; starch and polyvinyl alcohol foams remain partly phase-separate. Electron micrographs of the surface of such molded articles show swollen starch grains embedded in a polyvinyl alcohol matrix, while the interior instead looks homogeneous. The mixture remains phase-separate, since in contrast to extrusion no mixing action or only slight mixing action ensues during baking, and polyvinyl alcohol and starch are largely incompatible. Polyvinyl alcohol, which is a stronger and more-flexible polymer than starch, is suspected of binding together the swollen starch grains and thus increases the mechanical strength and stability of the molded articles. Extruded starch and polyvinyl alcohol foams, conversely, undergo intensive mixing, which is associated with the dissolution of the starch grain structure. 
     3. Since the final mold is formed directly during the baking process, cross-linking aids which increase the stability and water resistance can be admixed. This is not possible in the extrusion process, because a highly cross-linked material would not be adequately flowable. 
     It is advantageous in the process of the invention, before the addition of water, to add from 0.5 to 40% by weight, preferably from 0.5 to 24% by weight, relative to starch product, polyvinyl alcohol in dry form as fine powder to the other powdered ingredients to the baking composition and intimately mixed therewith; the polyvinyl alcohol has a degree of polymerization of over 1000, preferably over 1600 and in particular over 2000. To form a homogeneous suspension, water is added to the dry mixture in a quantity of 100 to 300% by weight, preferably 100 to 240% by weight, relative to starch product. 
     In another variant of the method of the invention, 0.5 to 40% by weight of polyvinyl alcohol in the form of an aqueous solution, preferably at maximum a 10% solution, is added to the baking composition; the polyvinyl alcohol has a degree of polymerization of over 1000, preferably over 1600 and in particular over 2000; and to form a homogeneous suspension, water is added to the dry mixture in a quantity of 100 to 360% by weight, preferably 100 to 240% by weight, relative to starch product. 
     Polyvinyl alcohol is produced by the polymerization of vinyl acetate and subsequent partial or complete saponification of the acetate groups. 
     General formula: ##STR1## n=approximately 200-5500, mostly 300-2500 R=H:&gt;97.5% fully saponified≦95.5 to 70% largely or partially saponified. 
     Polymers with a low residual acetyl content (down to approximately 2%) are classified as being fully saponified, and grades that are largely saponified (90 to 95%) and partly saponified (87 to 89%) are also commercially available. Individual manufacturers also offer a &#34;super&#34;-hydrolyzed grade, with a degree of saponification near 100%. 
     Toxicologically, no negative findings have been made. Polyvinyl alcohol is degradable; aqueous solutions should therefore require preservation. 
     The standard grades of polyvinyl alcohol can be classified by their viscosity (mpas in 4% aqueous solution), which goes along in parallel with the degree of polymerization (DP) and the mean molecular weight (number average) (source: TAPPI J., December 1988): 
     
         ______________________________________                         Molecular weight,Viscosity class          mPas, 4%                                   number average______________________________________high     45-70      2400-2600 95,000medium I       25-35                      1700-1800                                           65,000medium II          12-16                    900-1000                                           43,000low              2-7                        300-700                                           28,000______________________________________ 
    
     In the method of the invention, especially preferably, a fully-hydrolyzed polyvinyl alcohol is used. 
     It has proved to be advantageous that the suspension formed is left to rest before being applied to the mold, the resting time of the baking composition being preferably at least 30 minutes and preferably 45 to 60 minutes. 
     In the method of the invention, the following are preferred as the release agent: stearates of magnesium, calcium or aluminum, in a quantity of 0.05 to 20% by weight, relative to starch product, but at least 10%, relative to the concentration of polyvinyl alcohol; polymethyl hydrogen siloxanes in a quantity of 0.025 to 11% by weight, relative to starch product, but at least 5% by weight, referred to the concentration of polyvinyl alcohol; and monostearyl citrate in a quantity of 0.025 to 12% by weight, relative to starch product, but at least 5% by weight, referred to the concentration of polyvinyl alcohol are used, on the condition that at concentrations above 0.5% by weight, an at least partial neutralization is done with basic substances in solution or powder form, such as sodium hydroxide solution, potassium hydroxide solution, ammonia solution, water glass and calcium hydroxide, so that the pH value of the baking compositions does not drop below 5.0 and preferably not below 6.0. 
     The aforementioned release agents can also be used in arbitrary combination, wherein the total concentration does not drop below the lowest individual concentration and does not exceed the highest individual concentration. 
     The combination of polymethyl hydrogen siloxanes and monostearyl citrate is highly preferred. 
     Chemically, the monostearyl citrate (MSC), according to its manufacturers, is a mixture of monostearyl and distearyl citrate esters, which show action as oil-soluble chelating agents. The long fatty acid residues lend them their oil solubility, and the free carboxyl groups lend them the complexing action. 
     The CAS number is 1337-33-3.; the melting point is 47° C. and the solubility in oils is approximately 1% by weight. 
     The product used was procured from Reilly Chemicals, Brussels, Belgium, and then ground. The manufacturer is Morflex, Inc., Greensboro, N.C., USA. 
     21 C.F.R. (Volume 21, Code of Federal Regulations) lists the following FDA-approved uses for stearyl citrates: 
     GRAS as complexing agents up to 0.15% (§182.685) 
     Use as plasticizer in packaging materials for foodstuffs (§181.27) 
     As plasticizer for resin-like and polymer coatings (§175.300) 
     Components for paper and cardboard in contact with aqueous or fatty foodstuffs (§176.170). 
     Besides the zirconium compounds recited at the outset, compounds such as calcium hydroxide and calcium sulfate, which by ionic action modify the starch products during the baking process, can also be used for the sake of better cross-linking. As a result of all these provisions, a strengthening of the structure of the baked molded articles is obtained. 
     With the above-noted and other objects in view, there is also provided, in accordance with the invention, an article of manufacture shaped from a thin-walled material comprising starch and polyvinyl alcohol, wherein the material is characterized by a phase gradient between opposing surfaces of the thin-walled material, such that the starch and polyvinyl alcohol near the surfaces is biphasic with at least some of the starch characterized as substantially intact granules occupying a discontinuous phase and such that substantially all the starch near the center of the material between the surfaces is characterized by at least partially disrupted granules that are more highly interspersed with the polyvinyl alcohol relative to the starch near the surfaces. 
     In accordance with yet a further feature of the invention, the polyvinyl alcohol is present in an amount of 0.5 to 40% by weight of the starch. 
     In accordance with yet another feature of the invention, the polyvinyl alcohol and the starch are crosslinked. 
     In accordance with yet an added feature of the invention, the material comprises a moisture content in the range of about 7-12% by weight. 
     In accordance with a concomitant feature of the invention the article of manufacture includes an effective amount of a release agent. 
     Other features which are considered as characteristic for the invention are set forth in the appended claims. 
     Although the invention is exemplified and described herein as embodied in a method for producing disposable thin-walled molded articles, it is nevertheless not intended to be limited to the examples described, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. 
     The method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments and individual recipes. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The figures in the recipes each refer to 100 parts by weight of raw starch material with its natural water content. The solutions of polyvinyl alcohol were prepared while stirring and heating in deionized water (polyvinyl alcohol solution). Powdered raw materials are stirred in premixed form into the liquid ingredient. 
     The baking temperature is approximately 190° C. 
     Water absorption test: A molded article equilibrated for 45% relative humidity for seven days is filled with 100 ml of deionized water. After 25 minutes, the water is poured off and the increase in weight is determined in grams. 
     The mechanical strength tests are performed with an Instron universal testing machine. A pressure cylinder 35 mm in diameter is first moved from above to the molded article, which rests on a metal ring with an inside diameter of 80 mm; then at a feeding speed of 30 mm/min, a load and travel graph is recorded. From this, the load until break, the elongation until break, the deformation work and the modulus of elasticity can be calculated. 
     
         __________________________________________________________________________Recipe No. 1    2     3     4    5    6__________________________________________________________________________Bakingmold: cupStarch(1) 100  100   100   100  100  100PVAL  --     9.5(4)               10(4)                    9.5(4)                          10(5)                             10.5(6)solidRelease 2    1.9    2    1.9   2   2.1agent(2)Thickening 0.6  0.6      0.6                  0.3     0.6                            0.3agent(3)Water 100  114   110   114  110  126Release --   --    --    --   --   --agentViscosity 0.7  2.5      2.3                  0.7     7.0                            1.9after60 min.Baking 50   45     50   50    50  45time (sec)Baking 180  180   180   180  180  180temp.(° C.)Weight (g) 4.2  7.2      7.2                  6.5     5.7                            5.1Brittleness yes  red.  red.  Red. red. red.Adhesion no   yes   yes   yes  case-                            no                       wiseBaking no   yes   yes   yes  no   noresiduesDiscolor- no   yes   yes   yes  no   noationComments compar-      unsuit-            unsuit                  unsuit                       deterio- ison ableableable  rated__________________________________________________________________________ (1)Potato starch (2)Magnesium stearate (3)Guar (4)Poval B05, Denka, Japan, low molecular  DP approximately 550, partly hydrolyzed (5)Poval B24, Denka, Japan, high molecular  DP approximately 1700, partly hydrolyzed (6)Poval K17L, Denka, Japan, high molecular  DP approximately 2400, fully hydrolyzed 
    
     
         ______________________________________Recipe No.  7         8      9    10   11   12______________________________________Baking mold: cupStarch(1)   100       100    100  100  100  100PVAL solid(4)       --         0.5   2    5    10   20Release agent(2)       2         2      2    2    3    4Thickening agent(3)       0.3       0.3    0.3  0.3  0.3  0.3Water       100       100    103  107  115  132Viscosity after 60minutesBaking time (sec)       50        50     45   45   45   45Baking temp. (° C.)       180       180    180  180  180  180Weight (g)  4.3       4.5    4.7  5.0  5.2  5.1Brittleness yes       +/-    red. red. red. red.Adhesion    no        no     no   no   no   noBaking residues       no        no     no   no   no   noDiscoloration       no        no     no   no   no   noComments    comparison                 (5)______________________________________ (1)Potato starch (2)Magnesium stearate (3)Guar (4)Poval K17L, Denka, Japan, high molecular  DP approximately 2400, fully hydrolyzed (5)Brittleness reduced slightly 
    
     
         __________________________________________________________________________Recipe No.    13  14   15   16   17   18__________________________________________________________________________Baking mold:plateStarch(1)    100 100  100  100  100  100PVAL solution 10%    --      25(4)                25(4)                     50(4)                         100(4)                               50(5)Release agent(2)    1.8    1.8                1.8                     1.9                          2.1                             2Thickening    0.5 0.6  --   --    --   --agent(3)Water    100  75   75   50     6.7                            110Filler(6)    --  --   --   --   --    10Baking time (sec)    120 120  145  120  130  140Baking temp. (° C.)    200 200  200  200  200  200Weight (g)    14    14.5              16   17    17.5                             22Brittleness    yes red. red. red. red. red.Adhesion no  no   no   no   no   partlyBaking residues    no  no   no   no   no   yesDiscoloration    no  no   no   no   no   noComments compar-                 dete-    ison                    rio-                            rated__________________________________________________________________________ (1)Potato starch (2)Magnesium stearate (3)Guar (4)Airvol 525, Air Products, USA, &gt;98% hydrolyzed, DP approximately 1600 (5)Mowiol 10-98, Hoechst, Germany, &gt;98% hydrolyzed, DP approximately 1000 (6)SEStandard, Naintsch, Austria 
    
     
         ______________________________________Recipe No.    19      20       21     22     23______________________________________Baking mold:plateStarch(1)    100     100      100    100    100PVAL solution    --          25(4)                        50(4)                              100(4)                                     217(5)10% W/WRelease  1.8        1.8      1.8    1.8    2.17agent(2)Thickening    0.55       0.25  --     --     --agent(3)Water    103      75       55     0     --Sodium   --      --        1      1        1.1hydroxide40 g/lBaking time    130     115      105    115    100(sec)Baking temp.    200     200      200    200    200(° C.)Weight (g)    23.5      22.5    20     18.5   12Brittleness    yes     red.     red.   red.   red.Adhesion no      no       no     no     partlyBaking   no      no       no     no     noresiduesDiscoloration    no      no       no     no     noComments compari                        deterio-    son                            rated______________________________________ (1)Cornstarch (2)Magnesium stearate (3)Guar (4)Airvol 325, Air Products, USA; 98% hydrolyzed, DP approximately 1600 (5)Airvol 350, Air Products, USA; 98% hydrolyzed, DP approximately 2400 
    
     
         ______________________________________Recipe No.   24       25       26     27     28______________________________________Bakingmold: plateStarch(1)   100      100      100    100    100PVAL      217(4)    97(4)    50(5)                              100(5)                                     217(5)solution10% W/WRelease    2.17     1.93     1.8    1.8    2.17agent(2)Thickening   --       --       --     --     --agent(3)Water     43.5     48.5    50     20    --Sodium     1.1    1        1      1        1.1hydroxide40 g/lViscosity   600      600      800    500    130after 60minutesBaking time    90      100      120    110    115(sec)Baking  200      200      180    180    180temp.(° C.)Weight (g)      9.5    15       21     19     12Brittleness   red.     red.     red.   red.   red.Adhesion   no       no       no     partly yesBaking  no       no       yes    yes    yesresiduesDiscolor-   no       no       no     no     noationComments                  deterio-                            deterio-                                   deterio-                     rated  rated  rated______________________________________ (1)Cornstarch (2)Magnesium stearate (3)Guar (4)Airvol 350, Air Products, USA; 98% hydrolyzed, DP approximately 2400 (5)Airvol 523, Air Products, USA; 88% hydrolyzed, DP approxinately 1600 
    
     
         ______________________________________Recipe No.      29        30       31______________________________________Baking mold: plateStarch(1)       100       100      100PVAL solution 10% W/W              50(4)    100(4)   100(4)Release agent(2)              1.8       1.8      2.0Thickening      --        --       --agent(3)Water            50        20      --Baking time(sec)           120       120      115Baking temperature (° C.)           200       200      180Weight (g)        16.5     16       12Brittleness     red.      red.     red.Adhesion        partly    partly   partlyBaking residues yes       yes      yesDiscoloration   no        no       noComments        deterio-  deterio- deterio-           rated     rated    rated______________________________________ (1)Potato starch (2)Magnesium stearate (3)Guar (4)Airvol 523, Air Products, USA; 88% hydrolyzed, DP &gt;2400 
    
     
         ______________________________________Recipe No.   32       33       34     35     36______________________________________Bakingmold: fast-food shellwith hingeStarch(1)   100      100      100    100    100PVAL    --         210(5)   158(5)                              105(5)                                    105(5)solution 10%W/WRelease    1.8      3.4      3.4 3      3agent(2)Thickening      0.5   --       --     --     --agent(3)Fibrous --       --        2      4     6material(4)Water   100      --        25     65    75Weight (g)     21.3     19.2     18.9   18.6  18.0Brittleness   yes      red.     red.   red.   red.Adhesion   no       partly   no     no     noBaking  no       no       no     no     noresiduesDiscolor-   no       no       no     no     noationComments   compar-  hinge    hinge  hinge  hinge   ison;    works    works  works  works   hinge   breaks______________________________________ (1)Potato starch (2)Magnesium stearate (3)Guar (4)Cellulose fiber (5)Mowiol 66-100, Hoechst, &#34;superhydrolyzed, high molecular 
    
     
         __________________________________________________________________________Recipe No.  37    38   39   40   41   42__________________________________________________________________________Baking mold:cupStarch(1)  100   100  100  100  100  100PVAL powder     10(4)           10(4)                7(5)                  --   --      10(4)PVAL solution  --    --   --     110(6)                         110(6)                            --10%Release   3     3    3    3    3    3agent(2)Thickening  --    --      0.6                  --   --   --agent(3)Glycerin, 87%  --     5   --   --    5   --Wheat fiber  --    --   --   --   --    5Water  115   115  115  32   32   158Weight (g)     5.7           6.8                6.3                    4.9                       --      4.9Baking time   40    45   32  40   45    35(sec)Brittleness  red.  red. Red. red. red. red.Adhesion  no    no   partly                  no   no   noBaking no    no   no   partly                       partly                            noresiduesDiscoloration  no    no   no   no   no   noComments  more                 poor  flexible             unmolding  than 38!__________________________________________________________________________ (1)Potato starch (2)Magnesium stearate (3)Guar (4)Airvol 523S, Air Products, USA; 88% hydrolyzed, DP approximately 1600 (5)Poval K17, Denka, Japan, high molecular, fully hydrolyzed (6)Fluka, molecular weight 72,000, fully hydrolyzed 
    
     
         ______________________________________Recipe No.   43       44       45     46     47______________________________________Bakingmold: cupStarch(1)   100      100      100    100    100PVAL       15(4)    15(5)    15(6)                               5(4)                                      5(4)powderRelease  3        3        3      3      3agent(2)Thickening   --       --       --        0.3    0.3agent(3)Filler(7)   --       --       --     --      3Water   160      126      130    100    108Weight (g)      4.9      4.9      4.9    4.2    4.1Brittleness   red.     red.     red.   red.   Red.Adhesion   no       no       no     no     noBaking  partly   slight   no     partly partlyresiduesDiscolor-   no       no       no     no     noationComments   deterio- deterio-        deterio-                                   deterio-   rated    rated           rated  rated______________________________________ (1)Potato starch (2)Magnesium stearate (3)Guar (4)Airvol 523S, Air Products, USA; 88% hydrolyzed, DP approximately 1600 (5)Fluka, PVAL, molecular weight 100,000, 86-89% hydrolyzed (6)Fluka, PVAL, molecular weight 72,000, 97.5-99.5% hydrolyzed (7)Ulmer Weiβ HMH 
    
     
         ______________________________________Recipe No.   48       49       50     51     52______________________________________Bakingmold:fast-foodshell withhingeStarch(1)   100      100      100    100    100PVAL       8(5)     21(6)    15(6)                               10(6)                                      10(7)Release  3          3.5    3      3      3agent(2)Thickening      0.1   --       --        0.3    0.3agent(3)Fibrous --       --        5      5      3material(4)Water   125      185      150    135    115Brittleness   red.     red.     red.   red.   red.Adhesion   no       no       no     no     noBaking  no       no       no     no     noresiduesDiscolor-   no       no       no     no     noationComments   hinge    hinge    hinge  hinge  hinge   works    works    works  works  works______________________________________ (1)Potato starch (2)Magnesium stearate (3)Guar (4)Cellulose fiber (5)Fluka, PVAL, molecular weight 72,000, fully hydrolyzed (6)Mowiol 66-100, Hoechst, &#34;superhydrolyzed, high molecular, ground (7)Airvol 523S, Air Products, USA; 88% hydrolyzed, DP approximately 1600 
    
     
         ______________________________________Recipe No.   53       54       55     56     57______________________________________Bakingmold: cupStarch(1)   100      100      100    100    100PVAL     7(5)       10(6)    10(7)                               10(7)                                      10(7)powderRelease 3         3        3      3      3agent(2)Thickening   0.6      --       --     --     --agent(3)Wheat   --       --       --      4      6fiber(4)Water   11       125      130    145    150Weight (g)   5.7         5.2      4.9    4.6    4.5Baking  40        40       40     40     40time (sec)Brittleness   red.     red.     red.   red.   Red.Adhesion   no       no       no     no     noBaking  no       no       no     no     noresiduesDiscolor-   no       no       no     no     noation______________________________________ (1)Potato starch/Biolys 3/1 Biolys = modified starch, Lyckeby Starkelsen, Sweden (2)Magnesium stearate (3)Guar (4)Vitacel WF 600, Rettenmaier, Germany (5)Poval K17, Denka, Japan, DP approximately 1700, fully hydrolyzed (6)Airvol 165, Air Products, &#34;superhydrolyzed, high molecular, ground (7)Airvol 523S, Air Products, USA; 88% hydrolyzed, DP approximately 1600 
    
     
         ______________________________________Recipe No.     58     59      60    61    62    63______________________________________Baking mold:     1      2       3     4     5     10platePotato starch     100    100     100   100   100   100PVAL solution,     0      0       89.7  89.7  201.7 377.610%,(1)Release   1.8    1.8     2     2     2.4   4agent(2)Thickening     0.5    0.7     0     0     0     0agent(3)Water     100    143     44.8  78.9  0     0Viscosity, Pa/s     6.5    1.5     35    4.5   45    58Weight (g)     16.3   11.4    13.7  10.8  10.4  10.5Baking time     130    120     130   115   130   95(sec)Water     --      13     10.6  8.7   8     10.5absorptionAdhesion  no     no      no    partly                                no    noBaking residues     no     no      no    yes   no    noDiscoloration     no     no      no    no    no    no______________________________________ (1)Airvol 350, &gt;98% hydrolyzed, DP approximately 2400 (2)Magnesium stearate (3)Guar 
    
     
         ______________________________________Load until break, N;       97      77      148   95   120  11645% rFLoad per g of weight       6       6.8     10.8  8.8  11.5 11Relative to recipe No.       100     114     182   148  184  18658Elongation to break;       5.1     6.2     7.7   8.3  13.4 11.445% rFRelative to recipe No.       100     122     151   163  263  22458______________________________________ 
    
     
         __________________________________________________________________________     Recipe No.     64   65   66   67   68   69__________________________________________________________________________Baking mold: plate     25   26   27   33   35   38Potato starch                                    100PVAL solution, 10%       89.7(1)            93.8(1)                201.7(1)                      89.7(2)                          201.7(2)                               205.5(3)Release agent(4)                                    2.1Water          26.9               82.6                                      0Viscosity, Pa/s                                      9Weight (g)          17.3               11.1                    13.1                         15.6                              12.4                                   12.6Baking time (sec)                                    130Water absorption          10.2                         18.4                              16.8                                   18.5Adhesion     no            yes                  no                       no                            no                                 noBaking residues                                     noDiscoloration                                     no__________________________________________________________________________ (1)Airvol 325, &gt;98% hydrolyzed, DP approximately 1600 (2)Airvol 540, 88% hydrolyzed, DP approximately 2000 (3)Airvol 523, 88% hydrolyzed, DP approximately 1600 (4)Magnesium stearate 
    
     
         ______________________________________Load until break, N; 45% rF          210    88     150  139  126  149Load per g of weight                12.1                       7.9                                             11.8Relative to recipe No. 58                 203                       133                                              198Elongation to break; 45% rF                 8.1                       6.3                                              8.7Relative to recipe No. 58                 159                       124                                              171______________________________________ 
    
     
         ______________________________________      Recipe No.      70    71     72      73    74______________________________________Baking mold: plate        40      41     42    48    49Cornstarch         100                      100                             100                              100(2)                                    100(2)PVAL solution, 10%,(1)                0                     98.9                             222                                          205Release agent(3)              2.6                      2.6                             3.6                                              2.4Thickening agent(4)              1.6                                                0Water            185.7                     98.9                            11.1                                              5.7Viscosity, Pa/s              9.8                                               56Weight (g)          16                     14.5                            13.7                                              8.5Baking time (sec)              115                      120                             110                                               80Water absorption               12                     12.8                            10.4                                   --                                              7.5Adhesion        no     yes     no               noBaking residues               no                      yes                                               noDiscoloration               no                       no                                               no______________________________________ (1)Airvol 350, &gt;98% hydrolyzed, DP approximately 2400 (2)Wax cornstarch (3)Magnesium stearate (4)Guar 
    
     
         ______________________________________Load until break, N; 45% rF          88      81     106   32   70Load per g of weight                5.5                        5.6                                          8.2Relative to recipe No. 58                 92                         94                                          138Elongation to break; 45% rF                3.8                                          6.7Relative to recipe No. 58                 75                         98                                          131______________________________________ 
    
     
         ______________________________________      Recipe No.      75    76      77      78    79______________________________________Baking mold: plate        43      44      45    46    47Cornstarch         100                      100                                               100PVAL solution, 10%                0                        0                        222(1)                              223(1)                                    223(2)Release agent(3)              2.4                      2.4                                             3Thickening agent(4)              1.6                      1.6                                                 0Water            173.3                    173.3                                              11.3Calcium hydroxide,             0.22                     0.88                                              0.27powderedHydrogen peroxide, 30%                0                        0                                              3.56Viscosity, Pa/s               12                       13                                               8.5Weight (g)        15.3                     15.1                                              10.7Baking time (sec)              120                      120                                                85Water absorption              9.7                        8                                                13Adhesion        no      no                       noBaking residues               no                      yes                                                noDiscoloration               no                       no                                                no______________________________________ (1)Airvol 350, &gt;98% hydrolyzed, DP approximately 2400 (2)Airvol 325, &gt;98% hydrolyzed, DP approximately 1600 (3)Magnesium stearate (4)Guar 
    
     
         ______________________________________Load until break, N; 45% rF          95      75     106   73   68Load per g of weight                6.2                                          6.4Relative to recipe No. 58                104                         83                                          107Elongation to break;  45% rF                4.4                        3.7                                          5.5Relative to recipe No. 58                 86                         73                                          108______________________________________ 
    
     
         ______________________________________Recipe No.   80     81      82   83   84   85______________________________________Baking mold: plate        17     18      19   20   21   22Potato starch        100    100     100  100  100  100PVAL solution, 10%(1)        0      211     211  0    211  0Release agent(2)        2.1    2.2     0    2.2  2.2  2.2Thickening agent(3)        1.5    0       0    1.5  0    0Water        152    0       0    152  0    152Calcium hydroxide,        0.42   0.51    0.51 0    0    0powderedCalcium sulfate,        0      0       0    0.43 0.51 0powderedCross-linking        0      0       0    0    0    1.27*agent(4)Viscosity, Pa/s        --     120     170  7.4  120  --Weight (g)   17.8   13.6    16.4 11.4 10   23.6Baking time (sec)        160    150     135  130  130  175Water absorption        11     4.4     6.6  10.6 6.1  13.4Adhesion     no     no      yes  no   no   noBaking residues        yes    yes     yes  no   no   yesDiscoloration        no     no      no   no   no   no______________________________________ (1)Airvol 350, &gt;98% hydrolyzed, DP approximately 2400 (2)Magnesium stearate (3)Guar (4)Ammonium zirconium carbonate (Bacote 20) *Adjustment of pH to 9.5 with 1N KOH before the addition 
    
     
         ______________________________________Load until break, N;        88     172     170  65    129  11645% rFLoad per g of weight        4.9    12.6    10.4 5.7   12.9 4.9Relative to recipe No.        83     213     174  96    217  8358Elongation to break;        4.5    7.8     --    5.1  7.8  545% rFRelative to recipe No. 58        88     153     --   100   153  98______________________________________ 
    
     
         __________________________________________________________________________     Recipe No.     86    87    88    89    90__________________________________________________________________________Baking mold: plate     23    24    28    29    30Potato starch                                                100PVAL solution, 10%     215(1)           215(1)  .sup.                 223(2)                       223(2)                             222(2)Release agent(3)                                            1.9Water                                                  0Cross-linking agent                                       3.17(5)#Viscosity, Pa/s                                                 31Weight (g)                                               17.1Baking time (sec)                                                130Water absorption                                                3.9Adhesion                                          noBaking residues                                                 noDiscoloration                                                 no__________________________________________________________________________ (1)Airvol 350, &gt;98% hydrolyzed, DP approximately 2400 (2)Airvol 325, &gt;98% hydrolyzed, DP approximately 1600 (3)Magnesium stearate (4)Ammonium zirconium carbonate (Bacote 20) *Adjustment of pH to 9.5 with 1N KOH before addition **Adjustment of pH to 9.4 with 1M ammonia before addition (5)Zirconium acetate solution (22% ZrO2) #Adjustment of pH to 4.7 with 1N acetic acid before addition 
    
     
         ______________________________________Load until break, N; 45% rF          113     267    204   158  174Load per g of weight                 7.4                        12.8                               10.9                                          10.2Relative to recipe No. 58                 124                         216                                           171Elongation to break; 45% rF                 3.7                         8.4                                           5.2Relative to recipe No. 58                  73                         165                                           102______________________________________ 
    
     
         ______________________________________Recipe No.91          92       93       94     95______________________________________Baking 7        8        31     32     666mold:platePotato                                                  100starchPVAL   221(1)   220(1)   225(2) 221(2)                    0solution,10%Release          2.2(3)                   2.2(4)                                  1(3) + 1(4)agentThick-                                              0.5eningagent(5)Water                                                   110Viscosity,                                                    39Pa/sWeight (g)                                                    18Baking                                                  100time (sec)Water                                      --  5.9absorptionAdhesion                                                    noBaking                                                   noresiduesDis-                                                     nocoloration______________________________________ (1)Airvol 350, &gt;98% hydrolyzed, DP approximately 2400 (2)Airvol 325, &gt;98% hydrolyzed, DP approximately 1600 (3)Magnesium stearate (4)Monostearyl citrate (5)Xanthan 
    
     
         ______________________________________Load until break, N; 45% rF          64     81      200   146   --Load per g of weight                8.8                         9                                            --Relative to recipe No. 58                147                       151                                            --Elongation to break; 45% rF                7.5                       7.2                                            --Relative to recipe No. 58                147                       141                                            --______________________________________ 
    
     
         ______________________________________Recipe No.96          97       98     99   100    101______________________________________Baking 65.1     .2       .3   .4   .5     .6mold:platePotato        100                 100                                     100                                            100starchPVAL            0                   0                                             10powder(1)Release           2                   2                                              3agent(2)Release           0                   0                                              1agent(3)Thick-     0.6(4)              0.6(4)                                  0.5(5)                                         0.5(5)eningagentHydrogen           0                   0                                              4peroxide,30%Calcium           0                 0.5                                              0hydroxide,powderedWater         110                 110                                     130                                            130Viscosity,         1.1                 1.4                                     4.5                                            4.5Pa/sWeight (g)        17.5                23.4                         19.6                              17.1                                    17.1                                           14.1Baking        100                 130                                             90time (sec)Adhesion      no      no       no                            no                                  no     noBaking         no                  no                                             noresiduesDis-           no              slight                                             nocoloration______________________________________ (1)Airvol 523, 88% hydrolyzed, DP approximately 1600 (2)Magnesium stearate (3)Polymethyl hydrogen siloxane NM203 (4)Guar (5)Xanthan 
    
     
         __________________________________________________________________________Recipe No.  102 103 104 105 106 107 108 109__________________________________________________________________________Baking mold:plateStarch 100(1)      100(1)          100(2)              100(2)                  100(3)                      100(3)                          100(4)                              100(4)PVAL sol.,  0   203(5)          0   223(5)                  0   205(6)                          0   222(6)10% in waterRelease  1.6 2   2   2.4 2   2.4 2   3.6agent(7)Thickening  0.8 0   1   0   1   0   1   0agent(8)Water* 142 0   159 1.6 148 5.7 171 11.1Weight, (g),  8.7 8.2 11.2              13  7.4 8.5 14  13.750% rH**Baking time  85  85  110 120 75  80  110 110(sec)Baking temp.  200 200 200 200 205 205 205 205(° C.)Adhesion  no  no  no  no  no  no  no  noBaking no  no  no  no  no  no  no  noresiduesDiscoloration  no  no  no  no  no  no  no  noLoad until  18  51  38  49  14  35  42  70break (N),20% rH**Elongation to  2.9 6.8 2.9 3.9 2.4 4   2.4 2.5break (mm),20% rH**Load until  46  74  70  141 26  66  72  106break (N),50% rh**Elongation  6.6 11.5          6.3 9.1 5.2 6.6 4   5.6tobreak (mm), 50% rh**Load per g  5.3 9   6.3 10.8                  3.5 7.8 5.1 7.7of weight,50%**__________________________________________________________________________ *33% total solids **after 7 days equilibration (1)Potato amylopectin (Lyckeby Starkelsen, S) (2)Potato starch (Avebe, NL) (3)Waxy maize starch (Amioca, National Starch) (4)Corn starch (Buffalo 3401, CPC International, USA) (5)Airvol 325, &gt;98% hydrolyzed, DP approximately 1600 (6)Airvol 350, &gt;98% hydrolyzed, DP approximately 2400 (7)Magnesium stearate (8)Guar gum 
    
     
         __________________________________________________________________________Recipe No.    110 111 112 113 114 115 116 117__________________________________________________________________________Baking mold:plateStarch   100(1)        100(2)            100(2)                100(2)                    100(2)                        100(2)                            100(3)                                100(3)PVAL solution,    0   0)  101(4)                0   169(4)                        225(4)                            0   230(5)10% in waterRelease agent    2   1.8 4.1 2   4.3 4.5 2   2(6)Thickening    1   0.6 0   1   0   0   1   0agent(7)Water    167 135 17.4                146 19.2                        0   167 7.6% solids 33  39  46  37  37  34  33  33Weight (g),50% rH    27.3        25.3            33.4                20  18.1                        16.5                            10.7                                10.5**Baking time    180 110 110 95  90  110 80  80(sec)Baking temp.    205 200 210 205 210 210 205 205(° C.)Product  irregu-        smooth            smooth                smooth                    smooth                        irregu-                            smooth                                smoothappearance    lar                 larAdhesion no  no  no  no  no  no  no  noBaking residues    no  no  no  no  no  no  no  noDiscoloration    no  no  no  no  no  no  no  noLoad until   76  134 54  101 65  34  54break (N),20% rH**Elongation to        2.1 2.6 2.7 3.7 4.4 2.7 3.4break(mm),20% rH**Load until break,        125 292 126 161 148 59  86(N), 50% rH**Elongation to        2.9 7.8 5.9 8.1 10.6                            6.9 8.1break(mm),50% rH**Load per g of        4.9 8.7 6.3 8.9 9   5.5 8.2weight, 50%**__________________________________________________________________________ **after 7 days equilibration (1)50%amylose corn starch (Amaizo 5, American Maize, USA) (2)50%amylose corn starch derivate (Amaizo Crisp Tex, American Maize, USA (3)Corn starch derivate (Ethylex 2095, A.E. Staley, USA) (4)Airvol 350, &gt;98% hydrolyzed, DP approximately 2400 (5)Airvol 523, &gt;88% hydrolyzed, DP approximately 1600 (6)Magnesium stearate (7)Guar gum 
    
     
         ______________________________________              Recipe No.              118   119______________________________________Baking mold: plateStarch(1)                               100PVAL solution, 15% in water                 254(3)  254(3)Release agent(4)            2.6                               2.6Water                                    21% PVAL relative to starch                                    38% solids in batter                       33Weight (g), 50% rH**                   14.2Baking time (sec)                       125Baking temp. (° C.)                                   200Adhesion                     no                            slightBaking residues                      slightDiscoloration                            noLoad until break (N), 20% rH**                        73                               117Elongation to break (mm), 20% rH**                                   5.1Load until break (N), 50% rH**                                   156Elongation to break (mm), 50% rH**                                   9.4Load per g of weight, 50% rH**                                  11.0______________________________________ (1)Potato Starch (Avebe, NL) (2)Airvol 325, &gt;98% hydrolysed, DP approximately 1600 (3)Airvol 523, &gt;88% hydrolysed, DP approximately 1600 **after 7 days equilibration 
    
     
         ______________________________________     Recipe No.     120  121      122    123    124______________________________________Baking mold: plateStarch(1)          100                                              100PVAL-solution, 10%               203(2)        205(3)                                    205(3)in waterRelease agent(4)              1.6                     2.0                                   2.0                                          2.1Thickening agent(5)              0.8                                                0Aspen fiber(6)                                                5Water              142                                               16% solids                                            33Tray weight (7 days,              8.7                                              7.950% rH)Baking time (sec)                                               80Adhesion        no         no                           no                                           noBaking residues                                               noDiscoloration                                               noLoad until break (N),           18         51                           22                                           5920% rHElongation to break              2.9                                              7.3(mm) 20% rHLoad until break (N),                                               5650% rHElongation to break              6.6                                              7.3(mm) 50% rHLoad until break (N),                                               3780% rHElongation to break                                             11.4(mm) 50% rHLoad until break (N),                          2985% rHElongation to break              5.0                         8.0(mm) 85% rHLoad per g of weight              5.3                                              7.150% rH______________________________________ (1)Potato amylopectin (Lyckeby Starkelsen, S) (2)Airvol 325, &gt;98% hydrolyzed, DP approximately 1600 (3)Airvol 350, &gt;98% hydrolyzed, DP approximately 2400 (4)Magnesium stearate (5)Guar gum (6)Supplier: Super Wood Corp., Phillipps, WI 
    
     
         ______________________________________       Recipe No.       125   126    127    128  129  130______________________________________Baking mold: platestarch(1)            100                        100                                         100PVAL, powder(2)                7.5                                10PVAL solution, 10% in                                             82.5water(3)Release agent(4)                                                 0Release agent(5)               0.75                        1.0                                               0.9Water                110                        110                                               110plate weight, 50% rH               17.2                       17.7                                       17.4                                              16.9conditionedBaking time (sec)                110                        110                                               110Adhesion          no      no     no                                 no                                     no                                            noBaking residues                 no                                                noDiscoloration         no                                                no______________________________________ (1)Potato starch (Agrana, A) (2)Airvol 523S, 88% hydrolyzed, DP approximately 1600 (3)Airvol 350, &gt;98% hydrolyzed, DP approximately 2400 (4)Magnesium stearate (5)Polymethylhydrogensiloxane, Dow Corning 1107 fluid 
    
     
         ______________________________________Recipe No.  131     132     133   134  135  136______________________________________Baking mold: platePotato starch (1a)       100     100     100        100  100Wheat starch (1b)                 100Waxy potato                            100  100starch(1c)PVAL, powder(2)       16.7    16.7    10    10PVAL-solution, 10%                     0    100in water(3)Release agent(4)       5.0     5.0     3.0   2.0  2.0  2.0Release agent(5)       0       0       0     0    0    1.0Thickening  0.83    0.83    0.5   1.0  0.5  0agent(6)Aspen fiber(7)       0       0       5     0    0    0Mineral filler(8)       66.7    66.7    0     0    0    0Wax powder(9)       0       8.3     0     0    0    0Water       216.7   216.7   210   260  114  30plate weight,       18.0    22.0    10.0  7.7  8.4  8.0after bakingBaking time (sec.)       60      60      70    70   50   60Adhesion    no      slight  no    no   no   noBaking residues       slight  slight  no    no   no   noDiscoloration       no      no      no    no   no   noLoad until break       43      55(N), 40% rHElongation to       2.7     2.8break (mm) 40% rHLoad until break       48      50      46    43   41   68(N), 55% rHElongation to       3.6     3.9     5.8   5.5  4.4  6.3break (mm) 55% rH______________________________________ (1a)Potato starch (Agrana, A) (1b)Wheaten corn starch (Starch Australasia, Australia) (1c)Potato amylopectin (Lyckeby Starjeksebm S) (2)Airvol 523S, 88% hydrolyzed, DP approximately 1600 (3)Airvol 350, &gt;98% hydrolyzed, DP approximately 2400 (4)Magnesium stearate (5)Polymethyldrogensiloxane, Dow Corning 1107 fluid (6)Guar gum (7)Supplier: Super Wood Corp., Philipps, WI (8)Special Extender Naintsch BC60, (Luzenac Naintsch, A) (9)Hoechst Wachs OP Puler fein, (Hoechst, Germany) 
    
     The significant change in baking performance when powdered polyvinyl alcohol is used was especially surprising. It contributes both to shortening of the baking times and to an increase in weight and in the stability of the molded articles, even though because of an increase in viscosity when the polyvinyl alcohol powder is added, the amount of water in the recipe must be increased. A combination of adding powdered polyvinyl alcohol with inorganic fillers or organic fibrous materials in powdered form is especially advantageous. 
     This must be a specific unexpected property of polyvinyl alcohol, since other hydrophilic polymers, such as various hydrocolloids, with a similarly viscosity-increasing effect, do not exhibit this property. It can only be suspected that this has to do with the low compatibility between polyvinyl alcohol and starch (see &#34;Mowiol Polyvinylalkohol&#34; [Mowiol polyvinyl alcohol], company publication by Hoechst AG, 1984), or with the only-partial solubilization of the polyvinyl alcohol. On the microscopic level, this could lead to reduced pore growth in the baking process and thus to greater density of the molded articles, but it simultaneously makes the escape of steam easier and thus reduces the baking time relative to the proportion of water. 
     Electron micrographs show a higher-viscosity flow in the baking mold or better cohesion at the surface of the molded article, which is demonstrated also by the reduction in visible microscopic pores. 
     Another surprising observation (recipes 38 and 41) is that the addition of glycerin, which is a known plasticizer for polyvinyl alcohol, does not further increase the flexibility of the molded articles, measured by bend stress testing. In fact, a reduction was observed, although this could also be ascribed to the worsening of the baking performance (steaming out). Thus in example 41, for instance, there were also unmolding problems, and the baking time was increased. 
     The use of polyvinyl alcohol improves the mechanical properties of the molded articles, especially when there is a change in humidity, as shown by the following comparison: 
     Each 4 to 5 specimens are equilibrated at room temperature for one day at various relative humidities. Then by texture measurement, the breaking load (Fm), the deformation travel (Lm) and the work in joules (Wm) expended for the purpose are determined. 
     
         ______________________________________Recipe No.   % rF    Weight, g Fm (N) Lm (mm)                                   Wm (J)______________________________________13      22      15.5      74     3.0    0.11   50      15.2      95     4.2    0.21   80      15.7      98     6.3    0.3531      22      12.5      126    4.2    0.31   50      12.1      149    5.8    0.48   80      12.9      111    6.7    0.43______________________________________ 
    
     Example 13 (reference without polyvinyl alcohol) shows the following: 
     1. Despite increased weight, a reduced breaking load Fm and deformability to break Lm. 
     2. The work Wm to be expended for the deformation to break exhibits a significant rise, especially for low humidity. 
     These data indicate a greater flexibility of the molded articles. 
     Forming a flexible hinge as a connection between two mold halves has thus far been an unsolved problem in the production of starch-based molded articles. Admittedly, via a higher moisture absorption in conditioning, for instance at 75% relative humidity, the comparison recipes (No. 32 and 37) are also flexible enough that an unmolded hinge can be actuated repeatedly by opening and closing without breaking. Nevertheless, even at medium humidities around 40 to 60%, the vulnerability to breakage is so high that reliable function of such a hinge no longer exists. 
     Recipes No. 33-36 and 38-42, however, exhibit reliable function: actuation at least ten times at 50% relative humidity. 
     Examples 58, 59: comparison examples without polyvinyl alcohol; they have high water absorption, lesser breaking load and stretchability. 
     Examples 60-63: the use of polyvinyl alcohol increases the breaking load and the stretchability. 
     The more highly diluted recipe 61 produces very lightweight molded articles, along with a tendency to adhesion and a slight formation of residues on the baking molds. A remedy is provided here by a more-effective release agent (see recipe 92). As recipes 62 and 63 show, it is also possible to use higher doses of polyvinyl alcohol (about 38% polyvinyl alcohol to starch in 63), but without producing marked improvements in mechanical performance. 
     Examples 64-69, with various types of high- and medium-molecular polyvinyl alcohol, show positive effects on the breaking load and the stretching performance. From example 65, the effect of great dilution or low viscosity on the adhesive action of baking compositions that contain polyvinyl alcohol is again apparent. 
     Examples 70-74: 70 and 73 are comparison examples with cornstarch and wax cornstarch, respectively. The mechanical parameters are somewhat below those of molded articles of potato starch, but they are also improved by polyvinyl alcohol. In example 71, a certain adhesive effect of low-viscosity recipes can again be seen. 
     Examples 75-84: The use of Ca(OH) 2  in recipes 75-82 produces comparatively denser, heavier and hence more-solid molded articles, but conversely the stretchability is slightly reduced. Using polyvinyl alcohol jointly together with Ca(OH) 2  reduces the water absorption here significantly (recipes 77, 78, 81, 82). Ca(SO 4 ) also shows this influence (see recipes 80, 83 and 84). The baking residues formed by calcium hydroxide are unproblematic from a baking standpoint; no adhesion; no buildup of thicker layers. 
     Examples 85-90: Cross-linking reagents based on zirconium salt increase the product weight and the breaking load; together with polyvinyl alcohol, the water absorption is also especially effectively reduced. 
     Examples 91-95: Example 91, as a comparison example, exhibits the aforementioned adhesion problem in low-viscosity, more heavily diluted baking compositions, which can be avoided by monostearyl citrate. 
     Examples 96-101: Use of polyvinyl alcohol powder; comparison examples with and without Ca(OH) 2 . 
     Examples 102-109: Note the excellent elongation of potato amylopectin/PVOH plates at 20% humidity (#103) and also the good elongation of waxy maize/PVOH plates (#107). This is surprising since it is known in the art that the flexibility of extruded foams made from pure starch decreases as amylopectin content increases. In the present examples, it is hypothesized that PVOH occupies the continuous phase, thus leading to higher elongation to break. 
     Examples 110-117: As shown by recipe No. 110, regular high amylose corn is not suitable. For high amylose corn starch derivates, a minimum solids content over 35% is recommended. 
     Examples 118-119: Plates can be made from mixtures of starch and 15% polyvinyl alcohol even though such batters are very viscous. 
     Examples 120-124: In amylopectin starches (see also example 102-109) compared to regular starches we see higher strength increase, when PVAL is added, especially at low and high humidities. We assume, because here is no amylose to leach into the PVAL phase and make it less strong and flexible. Therefore the influence of fibers in example 124 is not as large as in former examples, e.g. of corn starch-fiber combinations. 
     Examples 125-130: Some examples with PVAL powder or solution together with different release agent or their combination. 
     Examples 131-136: Some more examples, 131 and 132 with higher concentration of inorganic fillers. Due to the additon of PVAL these still show acceptable mechanical properties.

Technology Classification (CPC): 8