Plastic and nonmetallic article shaping or treating: processes – Forming articles by uniting randomly associated particles – With liberating or forming of particles
Reexamination Certificate
1999-06-25
2002-12-31
Tentoni, Leo B. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Forming articles by uniting randomly associated particles
With liberating or forming of particles
C264S116000, C264S122000, C264S913000, C264S914000, C264S920000, C162S004000
Reexamination Certificate
active
06500373
ABSTRACT:
TECHNICAL FIELD
The invention relates to a method of manufacturing a molded product of multiple-component mainly composed of waste plastics or wastepaper, and presents a method of recycling materials without having to classify waste plastics. For example, by processing into a material board, a panel usable as substitute for building material or civil engineering material is presented.
BACKGROUND ART
Industrial waste and domestic waste were once products made of various materials such as plastics, and for recycling of resources, it is required to separate and classify the materials, and single materials being separated and classified are collected as recycled resources. In particular, plastic materials have problems of specificity as high molecular binders, and it has been considered impossible to mix different materials, and fuse and mold again according to the theory of compatibility, and if fused and molded, the required strength as product could not be obtained sufficiently.
For example, in the case of recycling of PET bottles, the main body resin is integrally molded of polyethylene terephthalate resin (PET resin), but the label area is made of polystyrene resin (PS) in consideration of printability. The cap is made of polypropylene resin (PP) in consideration of moldability, and the PET bottles made of three materials are separated and classified, and the PET resin of the main body is processed into fibers, and used in weaving of carpets, working clothes, etc. at the present.
Waste plastics from automotive parts are treated for oiliness, and recycled as the liner of automobile carpets or undercoating agent for the bottom of the car body in the factories of, the major automakers at the present, but it is not intended to recycle waste plastics discharged in the general market, and examples of recycling into building materials in a different market are not known yet.
Moreover, building plywoods were mainly wood bonds using tropical woods, and products were mainly composed of wood materials and wood pieces such as veneer, plywood, particle board, fiberboard, wood piece cement board, and gypsum particle board, and conifer woods are pressed and adhered by using adhesive as in particle board and fiberboard at the present. For example, as disclosed in Japanese Laid-open Patent No. 8-93217, resin plywoods made of rigid urethane resin are also developed, but they are also integrally molded by extrusion by laminate fusing method of injection molding method by adhering resin sheets, and the resin materials used therein are only single resins which are used by fusing and molding.
Although effective utilization of resources is requested, the recycling rate of waste plastics is only 2.9%, or 260,000 tons a year (1996). The rest is processed by methods causing to produce carbon dioxide such as use as fuel or incineration. The recycling rate of wastepaper is 53.5% (15 million tons), and this rate is not improved for several years.
The problem is that recycling requires separation and classification of waste matter composed of various materials, and the present processing method is limited for recycling as single materials. Concerning waste plastics, 300 to 1000 kinds of plastic resins are distributed in market, and once released into the market, it is nearly impossible to identify the materials in most resins.
Plastics are also called high molecular binders, and high polymers of different kinds are not miscible in the molecular order like water and oil. For example, polystyrene and polypropylene are similar in structural formula, but are not compatible. Thus being composed of multiple different molecular bonds, it is impossible to disperse different materials in the monomer units, and fuse mutually and mold again according to the theory of compatibility. If fused and molded, it is extremely difficult to satisfy the physical strength required in the product.
It is hence an object of the invention to present a method of manufacturing molded products by using waste plastics, wastepaper, wood pieces and others commonly, without sorting out from the refuse, by solving the problems mentioned above, and to present molded products of light weight for volume and having a sufficient strength at low cost by such method.
SUMMARY OF THE INVENTION
Plastic materials composed of noncompatible different polymers are formed into cellulose in sledge form to obtain cotton-like polymers, and mutually woven cellulose fibers are fused under heat and pressure, so that noncompatible different polymers can be integrally kneaded and molded. Herein, this molding method is called the cellulose molding method.
As different fibers in sledge form are woven together, high molecular meshes of different kinds are formed, and noncompatible different resins are used and molded again, and if aggregation begins due to temperature changes, since plastic fibers in compatible relation are woven together, peeling phenomenon can be avoided.
Further, by opening wastepaper, wood pieces and others, fibers having molecular skeleton containing cellulose, hemicellulose, lignin and others can be obtained.
Such fine fibers and plastic fibers are mutually woven and fused, and lignin is eluted to permeate into gaps of microphase separation of plastic fibers, so that an integral molded product is composed. Further, the cellulose failing to elute is mixed into the molded product as cellulose fibers, so that the physical strength may be satisfied.
Considering recycling of waste plastics, hitherto, it was general to grind plastics into fine pieces and fuse. High molecules of different kinds are not mutually fused in he molecular order like water and oil. For example, polystyrene and polypropylene are similar in structural formula, but are not compatible. Such fusible relation of plastics is generally understood as compatible relation or noncompatible relation. If fused, however, it is extremely difficult to satisfy the strength and other physical properties required in the product. FIG.
4
A and/or
FIG. 4B
shows a sample of fusing and molding different resins. In this case, using a biaxial extruder, polystyrene (outside) and polypropylene (inside) are extruded and spun, and the fusing temperature was 220 deg. C. in polystyrene and 180 deg. C. in polypropylene. The discharge was 2.4 cc/cycle, and interface tension was 5.1 mN/m. In the diagram, the polystyrene phase and polypropylene phase form an independent layer individually without being fused together. independent layer individually without being fused together.
On the other hand, known as polymer alloy, plastic materials are widely modified as new materials by mixing various components. Many practical examples are known. For example, the ABS resin widely used in automotive parts is known as a representative polymer alloy by copolymerization of polystyrene with butadiene or styrene. However, the forming method of polymer alloy is generally a chemical bond processing in a chemical plant, such as graft copolymerization or block copolymerization, and it is possible only by specifying the raw materials in both quality and quantity, and further using a solvent, and therefore in the case of waste plastics, if the quality and quantity of raw materials cannot be specified, it is difficult to obtain a product (molded product) satisfying the required quality, strength and other properties.
As other method, when different materials are fused and kneaded mechanically and by force, using an extruder or the like, a two-phase sea-island structure in emulsion form (see
FIG. 5
a
,
FIG. 5
b
, FIG.
5
C and/or
FIG. 5
d
.) is obtained, and it can be cooled and solidified, but since the surface tension between high molecules is small, as the noncompatible plastic resin aggregates by temperature change, phase separation begins, and peeling phenomenon may occur (note also page 10).
By such method, a fused product may be obtained by mixing different materials, but since the quality, quantity and properties of waste plastics cannot be determined, and hence the solvent cannot be specified, so that a perfect poly
Arent Fox Kintner & Plotkin & Kahn, PLLC
Tentoni Leo B.
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