Claims
- 1. A thermoplastic article comprising
- (a) a molded hollow body section of crosslinked thermoplastic resin material, and
- (b) at least two pieces of pipe of a non-crosslinked thermoplastic resin material communicating with the interior of said body section, wherein said body section has been rotationally molded from crosslinkable thermoplastic material in contact with and around said one end of said pieces of pipe of non-crosslinked thermoplastic material.
- 2. An article in accordance with claim 1 wherein both the hollow body section and said pieces of pipe consist essentially of a polymer of ethylene.
- 3. An article in accordance with claim 1 wherein at least the hollow body section consists essentially of high density polyethylene having a density of about 0.95 to 0.965 g/cc and a melt index measured in accordance with ASTM D-1238-65T Condition E of about 10 to about 30 g/10 min.
BACKGROUND OF THE INVENTION
This is a divisional application of our copending patent application Ser. No. 599,738, filed July 28, 1975, now U.S. Pat. 3,989,787.
This invention relates to plastic articles. In accordance with one aspect, this invention relates to plastic pipe fittings and plastic pipe connections. In accordance with another aspect, this invention relates to methods for making such plastic articles.
Articles with intricate shapes can be formed out of thermoplastic polymer materials. If such articles are to be connected to other units, they have been made out of non-crosslinked plastic polymers and such articles could easily be, for instance, welded to another unit. When a higher degree of mechanical stability or rigidity was desired, such articles were formed out of crosslinkable plastic polymer which was crosslinked during the molding step.
One process which is particularly advantageous for molding intricately shaped articles out of crosslinkable polymers is the rotational molding process. In this process, powder or granules of plastic polymer being crosslinkable and containing a crosslinking agent are introduced into a mold. The closed mold is then heated from the outside and rotated preferably around two axes with different rotational speeds. During this process the polymer fuses and crosslinks, thus forming a layer of crosslinked material on the inner surface of the mold. Sturdy articles with intricate shapes can economically be produced by this process. However, pipe connections or pipe fittings of crosslinked polymers have the serious drawback that they cannot be connected by standard techniques, e.g., welding or adhesive bonding, to other units such as pipes of non-crosslinked polymers or to other crosslinked sections.
It is thus one object of this invention to provide a novel plastic article.
Another object of this invention is to provide a novel plastic article which is both mechanically strong and which can be attached to other units.
Still another object of this invention is to provide a new pipe fitting or a new pipe connection.
A further object of this invention is to provide a process for the production of a novel plastic article.
US Referenced Citations (7)
Divisions (1)
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Number |
Date |
Country |
| Parent |
599738 |
Jul 1975 |
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Patent Grant
4076282
