Thermoplastic stock materials useful for producing flexible, thermoplastic bags or containers for food packaging are well known. Such thermoplastic stock materials can be single-layered or multi-layered. Typically, if the stock material is multi-layered, the inside and outside layers of the thermoplastic materials are different and have different melt temperatures with the inner layer having a lower melt temperature. Generally, in multi-layered stock materials the inner and outer layers are coextruded with a tie layer therebetween. In multi-layered thermoplastic stock materials having a plurality of layers, there is typically a tie layer provided between each pair of thermoplastic layers. Thus, in a thermoplastic stock material having one outer layer and one inner layer, there will be one tie layer therebetween. In a structure having three thermoplastic layers, there will be two tie layers provided.
Heretofore, excess scrap from the production of thermoplastic films or bags from a thermoplastic stock material has been discarded and sent to land fill. In some cases, the scrap can be used as an additional layer in a thermoplastic stock material. However, use of the scrap as an additional layer in a thermoplastic stock material would require the use of at least one additional tie layer to incorporate the additional scrap layer in the thermoplastic stock material. Use of the scrap as an additional layer involves the use of additional equipment, the necessity of additional tie layers and the expenses associated therewith. In addition, the use of scrap as an additional layer can cause a decrease in the performance and optical characteristics of a thermoplastic film.
It is, therefore, an object of the present invention to incorporate scrap material from the production of thermoplastic bags into a thermoplastic stock material in a manner which does not suffer from the disadvantages of known methods.
It is another object of the present invention to incorporate the scrap material in the tie layer of a coextrusion.
It is yet another object of the present invention to provide a process for using the scrap material which does not require the incorporation of an additional layer in a coextruded thermoplastic stock material.
A further object of the present invention is to provide a composition useful as the tie layer in a coextrusion, which tie layer comprises scrap material obtained from the production of thermoplastic film or bags from a thermoplastic stock material.
A still further object of the present invention is to provide a process for incorporating scrap material in a coextruded thermoplastic stock material which does not require the use of additional tie layers.
Yet another object of the present invention is to provide a three layer, coextruded thermoplastic stock material having scrap material incorporated in the tie layer of the stock material.
USPTO Backgrounds
USPTO Backgrounds