Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Composite having voids in a component
Reexamination Certificate
1998-06-19
2001-12-04
Lovering, Richard D. (Department: 1712)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Composite having voids in a component
C002S411000, C264S478000, C293S102000, C293S109000, C428S316600, C428S317700, C428S909000, C441S080000, C521S056000, C521S904000
Reexamination Certificate
active
06326077
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a composite polymeric material having high resistance to impact energy.
Specifically, the present invention relates to a composite polymeric material, to the corresponding preparation process and to manufactured articles having high impact energy absorption.
Currently, manufactured articles for automotive parts capable of absorbing impact energy, such as structures for vehicle interiors and exteriors, motorcycle crash helmets and others, are made of a single material having a polymeric base, such as expanded polystyrene, expanded polypropylene, or polyurethane foams.
These manufactured articles are generally produced with a molding technology which entails injecting an expandable polymer into a mold having a preset shape and then expanding the polymer in the presence of catalysts and/or expansion agents. At the end of the expansion, the polymer hardens and acquires the preset shape of the mold.
In particular, in the production of polyurethane manufactured articles, polyisocyanates and polyesters or glycols are injected into the mold and are made to polymerize in the presence of catalysts and expansion agents. During polymerization, the polyurethane foam forms and, by expanding, takes the shape of the mold.
However, manufactured articles resistant to impact energy made of a single polymeric material produced according to conventional technology are not free from having drawbacks in use, mainly due to the fact that they are made of a single polymeric material which does not provide an adequate resistance response to the impact and to the shock wave. In particular, the only variable that is available to the designer is the density of the material.
For example, impact-resistant manufactured articles made of a single polymer according to the prior art, particularly expanded polystyrene helmets for motorcycles, have the drawback that they lose their impact-resistance characteristics after a single impact that causes a permanent deformation of the structure.
In the case of fenders for cars or of motorcycle helmets, permanent deformation after an impact accordingly compromises their safety characteristics, forcing the user to replace the manufactured article.
SUMMARY OF THE INVENTION
One of the aims of the present invention is to eliminate or substantially lessen the drawbacks of the prior art.
Another object of the present invention is to provide a composite polymeric material which has high-level impact energy resistance characteristics and has a long life.
A further object of the present invention is to provide a composite polymeric material which is simple to produce and does not entail high production costs.
Yet another object is to provide a manufactured article made of composite polymeric material which combines low weight with high mechanical strength characteristics.
Another object of the invention is to provide a method for producing manufactured articles made of an impact-resistant composite material whose execution entails modest operating and energy-related costs.
With the foregoing and other objects in view, there is provided, in accordance with a first aspect of the present invention, a composite material comprising a pre-expanded polymer, preferably in granular form, selected from the group consisting of polystyrene, polypropylene, a copolymer of polystyrene with a melting point above 90° C. and mixtures thereof, dispersed in a resin selected from the group consisting of melaminic resin, phenolic resin, polyurethane resin and mixtures thereof, the polyurethane resin being the preferred one among them. The expression “polystyrene copolymer” denotes a product of polymerization of polystyrene with another polymer or an alloy of polystyrene with another polymer.
DESCRIPTION OF PREFERRED EMBODIMENTS
Among polystyrene copolymers having a melting point above 90° C., preference is given to those with a melting point above 100° C.; among these, particular preference is given to the copolymer of polyphenylene oxide (PPO) and polystyrene (PS). By way of example, mention is made of the copolymer of polyphenylene oxide and polystyrene marketed under the trade-name NORYL EF (in granules or expandable beads) by the General Electric Co., USA, and of the product of the Huntsman Chemical Co., Chesapeake, Va. USA, marketed under the trade-name GECET (polymeric alloy of PS-PPO).
The pre-expanded polymer used in the present invention has advantageously been subjected beforehand to an expansion process and has a granular, spherical or bead-like shape.
The composite polymeric material according to the present invention preferably consists of a uniform dispersion of pre-expanded granules or beads in a matrix of a polyurethane, melaminic or phenolic resin.
The composite material having a polymeric base, according to the present invention, has high impact energy absorption because, following an impact, the impact energy is transmitted along the resinous structure, which has acquired a cellular structure whose cells internally contain the expanded polymeric granules, which undergo elastic deformation and considerably contribute to damping propagation of the shock wave and to ensuring the preservation of impact energy-absorbing properties even with subsequent impacts.
In view of these characteristics, the composite material according to the invention is particularly suitable to provide lightweight manufactured articles having high mechanical strength and resistance to impact energy and to repeated impacts.
Said manufactured articles comprise, in variable amounts, the composite material according to the invention, alone or associated with other impact-resistant materials.
Comparative tests have shown that the manufactured articles according to the invention have higher energy absorption than polystyrene and, for an equal density with respect to polyurethane, are more resistant to impact energy and to repeated impacts.
The manufactured articles according to the present invention can be entirely made of the above-described composite material or are constituted by multilayer structures in which, for example, one or more layers are made of the composite material and the remaining layers are made of other materials (polymeric and nonpolymeric).
According to another aspect of the present invention, said manufactured article is a liner for helmets, for example of the type for motorcycles, cars, work or sport. Helmet liners manufactured with the composite polymeric material according to the invention are highly resistant to impact energy and in particular maintain their impact-resistance characteristics substantially unchanged even after one or more impacts.
In particular, it has been observed that the permanent deformation of the surface structure of the manufactured article according to the invention produced by a medium-energy impact does not compromise, except to a limited extent, its strength and safety characteristics, making them suitable for prolonged use.
According to a further aspect, the present invention relates to a life preserver which comprises the composite material described above. Advantageously, said life preserver is constituted by a core made of very hard polymeric material or wood or steel, covered with a layer of the composite material according to the invention. The life preserver according to the invention has a weight which can be likened to that of life preservers of the prior art together with high impact resistance.
In accordance with yet another aspect of the present invention, said manufactured article is an automotive interior, such as door paddings, door panes, knee bolsters, head restraint systems, sun vizors, instrument panels, rear parcel shelves, or an automotive exterior such as bumpers, body supports or an automotive cavity filling.
In accordance with another aspect of the present invention, a method for producing manufactured articles made of composite material is provided, said method comprising the steps of:
injecting into a mold a pre-expanded polymer selected from the group consisting of polystyrene,
Josif Albert
Lovering Richard D.
Modiano Guido
O'Byrne Daniel
LandOfFree
Composite polymeric material having high resistance to... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Composite polymeric material having high resistance to..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Composite polymeric material having high resistance to... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2587670