Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
1999-05-17
2001-09-04
Nutter, Nathan M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C524S013000, C524S017000, C524S018000, C524S022000, C524S023000, C524S025000, C524S026000, C524S047000, C524S072000, C524S076000
Reexamination Certificate
active
06284838
ABSTRACT:
BIODEGRADABLE COMPOSITION
The present invention refers to a biodegradable composition, which contains a lignin and/or a lignin-containing material and a protein, said composition being useful for the production of biodegradable shaped articles, for example throw-away articles, advertising articles, labels, cups, flower-pots, reels of thread, candle-cups, and the like as well as films, or foamed articles. The invention also refers to the articles, which are made from a material according to the present invention.
Lignin is a biodegradable raw material which is found abundant in nature. Lignin is a cell-wall material of wood, straw, and like materials and is obtained as a side-product when these materials are processed, especially in the production of wood-cellulose, which is the starting material for the paper industry. On the basis of the different processes used to isolate lignin, and the different types of lignin obtained therewith, lignin is named mainly as sulphate-lignin, or Kraft-lignin, sulphonate-lignin, organosolv-lignin which is obtained by extraction with organic solvents, like ethanol, or n-butanol, lignin which has been obtained by treatment with water vapour, or acid-hydrolysed lignin. The different processes to produce these lignins are the lignins obtained therewith have been described in the literature. All these lignins may be used for production of the compositions as defined herein later on.
For the use according to the present invention the lignin need not be relatively pure and isolated. It suffices to use directly a lignin containing material. It is possible to use wood or another lignin containing material directly, as a natural renewable raw-material, in place of isolated lignin. In sawmills wood is obtained in the form of sawdust in different sizes. Often boughs, branches of trees or bushes are treated in a shredder to produce small pieces. These materials may be used directly to produce shaped articles. In this sense, the present invention refers also to use of lignin containing materials, preferably in the form of small or fine particles, preferably in the form of small particles, optionally together with separately produced relatively pure lignin, to produce shaped articles which are dimensionally stable, yet biodegrade in nature. Proteins, lignins and lignin containing materials are well compatible and adhere well with each other chemically or physically when used according to the present invention. This yields good products which may be produced easily and are reproducible.
Articles made from biodegradable materials are known. The biodegradable materials according to the present invention are, compared with known materials, cheap and simply to make, for example in melt-processing by compression-molding by extrusion, or by injection molding. This depends on the selected composition. Products are obtained with very good properties having a high stability against humidity so that the physical properties remain stable within a large humidity range. Articles made therefrom have a natural color and according to the chosen composition for example also the natural color of wood which is very attractive. Compositions according to the present invention containing lignin, a protein and optionally a flame retardant have excellent self-extinguishing properties. The have an excellent price/performance ratio, which is an important factor for the commercial success.
The present invention is defined in the claims. The present invention especially refers to a biodegradable composition, which is characterized in that said composition has been obtained by heating and melting together at least one lignin and/or a lignin containing material with a protein, and that said composition optionally contains one or more additives, whereby said additives are selected from the group of modifying agents, alkenol polymers, fillers, lubricants, plasticizers, thermoplastic polymers, stabilizers, flame retardants, dyestuffs, nucleating agents, foaming agents, pigments and mixtures thereof. The weight ratio of the dry lignin and/or the dry lignin containing material on the one side to the dry protein on the other side in said composition is preferably from 99.95:0.05 to 20:80, preferably from 99.95:0.05 to 40:60, preferably from 98:2 to 60:40, and preferably from 97:3 to 75:25.
the present invention further refers to a starting composition which on heating and melting yields a composition according to the present invention, which is characterized in that said starting composition contains the following components: (i) a lignin and/or a lignin containing material; (ii) a protein which optionally has been deprotonated and (iii) optionally one or more additives which are selected from the group comprising of modifying agents, alkenol polymers, fillers, lubricants, plasticizers, thermoplastic polymers, stabilizers, flame retardants, dyestuffs, nucleating agents, foaming agents, pigments and mixtures thereof, wherein the weight ratio of the dry lignin and/or the dry lignin containing material on the one side to the dry protein on the other side in said composition preferably is form 99.95:0.05 to 20:80, preferably from 99.95:0.05 to 40:60, preferably from 98:2 to 60:40, and preferably from 97:3 to 75:25.
The composition may, depending on the chosen composition, by present in the form of a powdery mixture, a spray dried powder, a melt or a shaped article made thereof.
it is to be assumed that the lignin and the protein associate or bind together so that after heating a lignin/protein reaction product is obtained. This especially is the case, if a deprotonated protein is used as described further on. If a lignin containing material is used, for example wood, which is further in this text used as an expression including also other lignin containing materials, it may also be assumed that on heating, the protein associates with or binds itself to the reactive groups of the lignin which is contained in the wood. This may especially be assumed if deprotonated gelatine is used. On the basis of the increase of the viscosity of the mixture while processing it appears that a cross-linking reaction takes place. However, this explanation shall not limit the present invention.
If for example lignin and gelatine or deprotonated gelatine is mixed in a kneader at elevated temperature, a homogenous melt is formed initially, whereby on continued processing the viscosity of the composition increases. By cooling the composition it is possible to stop this increase resp. the cross-linking. By this it is possible to work with a two or multi-step process and initially produce a composition which is not cross-linked or only cross-linked to a low degree which in a further step is worked into the finished article. If the used granulate consists mostly of lignin and a protein then preferably a heated press is used for producing shaped articles as by the continuing cross linking and increasing viscosity an extruder or an injection moulding machine could be blocked. The selection of the apparatus to produce of the shaped article depends of the type of composition and presents no problem to the expert.
In order to produce the composition of the present invention it is convenient to mix the lignin and/or the lignin containing material with the protein, optionally under heating and subsequently adding the additives. It is also possible to mix the additives together with the lignin and/or the lignin containing material and heating the mixture. Preferably a granulate is produced initially, wherein the lignin and/or the lignin containing material is not crosslinked or pre-crosslinked with the protein. The granulate may then be mixed with further additives and processed to a shaped article applying heat.
If wood is used in the mixture it is possible to impregnate the wood with the protein and optionally with the lignin and further additives so that a granulate is obtained which can be processed under heat to yield a shaped article. Preferably the impregnated product is made from a wood containing of small particles. Such a
Ladas & Parry
Novamont S.p.A.
Nutter Nathan M.
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