Process for producing molded parts by polymerization of lactams

Details Process for producing molded parts by polymerization of lactams Process for producing molded parts by polymerization of lactams

1997-03-28

1999-11-09

Tentoni, Leo B.

Plastic and nonmetallic article shaping or treating: processes

Utilizing special inert gaseous atmosphere or flushing mold...

264102, 264257, 264258, 264310, 264DIG56, 528323, B29C 7012, B29C 7042

Patent

active

059807962

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The invention relates to a process for manufacturing molded parts by polymerization of lactams in molds with addition of fiber composite material. The invention relates furthermore to novel molded parts produced according to the inventive process.
The technical manufacture of molded parts from lactams, preferably by activated alkaline quick polymerization or block polymerization has been in use for approximately 30 years. The term molded parts in the context of the present invention refers to elements that can be produced with the known casting and polymerization techniques and which include semi-finished products, shaped elements etc.
In the field of machine and apparatus construction, for example, it has been attempted for many years to replace sheet metal with other materials that have technical and/or financial advantages in their manufacture and/or their application. As alternative materials, among others, plastic materials have found acceptance which have versatile properties and can be matched very precisely to respective requirements. However, to date no plastic material has been found with which can replace metals completely with respect to strength, stability, hardness, stiffness, tenacity, temperature resistance, behavior in fire etc. Insofar as individual plastic materials have at least partially reached the technological properties of metal or in some cases even surpass them, their use is, in general, not comparable to the use of metals with respect to economic considerations. It is thus still necessary to select for each application the respective optimal replacement plastic material from a great palette of possible variants in order to comply optimally with the respective profile of specifications.
Fields for the use of sheet plastic molded parts are the automobile industry and transportation. In these fields sheet molded parts are used which in the past have been made from sheet metal. In the recent past, these molded parts have been replaced in particular by thermosetting materials, whereby especially unsaturated polyester resins (UP resins), polyurethanes (PU resins), and epoxide resins (EP resins) have been popular. For mechanically minimally loaded parts, thermoplastic materials have been used more and more whereby mostly the mass-produced plastics polypropylene (PP), polycarbonate (PC), acrylonitrile butadiene styrene (ABS), and different mixtures are being used.
The plurality of employed plastic materials, especially in the automobile industry, has been considered more and more as a disadvantage in comparison to the metallic materials because in the recent past a need for recycling and reuse of the discarded old apparatus has developed. While the metal recycling problem has been solved for years substantially by scrap metal treatment, plastic recycling is still in the start-up phase. It has been shown already that a sorting according to plastic types is very complicated and expensive. Instead, it seams to be more useful to employ from the beginning only a small number of plastic materials. These plastic materials should then be used for the respective applications in large quantities, in the automobile industry, for example, for bumpers, side panels, fenders, roofs, the underbody groups, engine compartment hood etc. In this context, it is desirable to provide only one plastic material for a large number of applications.
Important parameters for recycling of plastics is the required energy expenditure and the reworking degree of the remaining plastic to new plastic parts. Conventionally, the plastic parts are comminuted and foreign materials are cleaned off. The resulting raw material is, in general, available in granular form. When a thermoplastic material is provided it can be used completely in injection molding machines to produce new parts. However, thermosetting plastics do not melt under comparable conditions and can only be used partially as a filler material when new thermosetting parts are produced. Thus, the thermoplastic materials due to their c

REFERENCES:
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patent: 3752623 (1973-08-01), Sinn et al.
patent: 3780157 (1973-12-01), Hechlhammer et al.
patent: 4182843 (1980-01-01), Haupt et al.
patent: 4508675 (1985-04-01), Salatiello et al.

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