The present invention relates to a multilayer structure including a starch layer (A), an adhesive layer (B), and a base material layer (C) in the order mentioned. In this multilayer structure, a material constituting the starch layer (A) comprises a starch and water; a material constituting the adhesive layer (B) comprises a thermoplastic resin having a density of 0.920 g/cm.sup.3 or lower and has an acid value of 0.3 mgKOH/g or higher; and the base material layer (C) is a layer having a tensile elastic modulus of 100 MPa or higher.

Disclosed is an acid-modified flour and a method of making the acid-modified flour. The acid-modified flour is desirably prepared using a dry milling process. A starting flour is combined with a strong acid to form a mixture. The mixture is heated. A neutralizer is added to increase the pH of the mixture. If desired, the mixture can be dried and any agglomerates can be removed. The acid-modified flour can be used as a binder in a slurry for preparing one or more gypsum layers in a gypsum board.

Starch-based packaging material and methods for making the material are described. The starch-based packaging material can comprise layers of expanded starch with a cellulosic web disposed between the layers. The expanded starch can be formed by extruding starch with water which acts as an expanding agent and causes the starch to expand resulting in an extrudate having a density of no more than about 5 lbs/ft.sup.3. An apparatus and methods for post-processing the expanded starch are described wherein the expanded starch is extruded as a tube that enters a funnel and is advanced forward by forced air. The tube passes over a blade where the tube is slit and subsequently opened up into a sheet by a second supply of forced air. The sheet then exits the funnel and can be calendered as well as stacked with subsequent lamination.

A composite structure 10 comprises one or more layers 12 of structural material and one or more layers of adhesive material 28 binding the one or more structural layers together. The one or more layers of structural material are coated with a bonding agent. The one or more layers of adhesive material are at least partially soluble or separable in water. A method of making a composite structure is also provided.

A multi-layer polymer film comprising at least one middle layer A, the polymeric constituents of which are soluble in aqueous solution, and at least one substantially water-impermeable covering layer B or C arranged above and/or below the at least one middle layer A, wherein the layers A, B and C independently of each other in each case comprise at least one thermoplastic polymer and at least one of the covering layers B and C comprises at least one polyhydroxyalkanoate. Processes for the production of the multi-layer polymer film according to the invention and its use for the production of molded parts, films or bags are furthermore presented and described.

A water activated tape and method of producing is provided, the tape comprising a repulpable material, a water-soluble material affixed to the repulpable material, and a water activated adhesive layer affixed to the water-soluble material.

Disclosed is an acid-modified flour and a method of making the acid-modified flour. The acid-modified flour is desirably prepared using a dry milling process. A starting flour is combined with a strong acid to form a mixture. The mixture is heated. A neutralizer is added to increase the pH of the mixture. If desired, the mixture can be dried and any agglomerates can be removed. The acid-modified flour can be used as a binder in a slurry for preparing one or more gypsum layers in a gypsum board.

There is provided a multilayer film comprising a starch layer and at least one other layer. The multilayer film has excellent barrier properties. The starch layer comprises a modified starch having a degree of substitution less than 1.5. Suitable other layers include polyolefins. The multilayer film finds use in packaging, particularly in packaging foodstuffs.

Disclosed are a composite gypsum board and a method of preparing composite gypsum board. The board contains set gypsum layers sandwiched between two cover sheets. The set gypsum layers are formed from at least stucco and water. The set gypsum layers include a board core and one or more skim coat layers. The set gypsum core makes up a substantial thickness (e.g., at least about 90%, at least about 92%, at least about 95%, or at least about 97%) of the total thickness of all the gypsum layers. A first skim coat layer is included on one side of the core, facing a first (face) cover sheet. A second skim coat layer is included on the other side of the core, facing a second (back) cover sheet. At least the second skim layer is formed from a slurry that contains starch. The stucco material generally includes a high salt impurity content, for example, when the stucco is calcined from certain sources of low-quality synthetic gypsum. For example, in some embodiments, the salts are chloride salts, e.g., sodium chloride (NaCl), potassium chloride (KCl), magnesium chloride (MgCl.sub.2), and/or calcium chloride (CaCl.sub.2).

There is provided a multilayer film comprising a starch layer and at least one other layer. The multilayer film has excellent barrier properties. The starch layer comprises a modified starch having a degree of substitution less than 1.5. Suitable other layers include polyolefins. The multilayer film finds use in packaging, particularly in packaging foodstuffs.