Polypropylene toys stabilized with hindered piperidine substituted 2-hydroxy-benzophenone
Publication Date: 2000-Oct-12
The IP.com Prior Art Database
Polypropylene toys stabilized with certain hindered piperidine substituted 2-hydroxy-benzophenone are described. These toys have a longer useful life and improved aesthetic value when compared to toys made with prior art compositions.
Polypropylene (PP) beach toys, such as beach shovels and buckets, have limited useful lifetimes due to degradation caused by harmful ultraviolet radiation from sunlight. Not only does sunlight cause the toys to become brittle, leading to breakage, but the sunlight also causes fading of pigments, resulting in a bleaching effect, with loss of aesthetic value.
It is proposed that the hindered piperidine substituted 2-hydroxy-benzophenone stabilizer shown in drawing 1 (attachment), when included as an ingredient in polypropylene, will inhibit the time to embrittlement and rate of color fading, thereby extending the useful life of toys made from such stabilized polypropylene.
The hindered piperidine substituted 2-hydroxy-benzophenone can be melt compounded into PP using a variety of well known methods, and can be added at a concentration of about 0.1% to 2% by weight of the total PP-based composition. Additional PP additives can be included as needed, to impart other needed properties.
The resulting stabilized polypropylene composition can be used to fabricate toys, or parts for toys, by a variety of well known methods, including injection molding, blow molding, and extrusion.
By way of example of the invention, 90 pounds of polypropylene are fluxed in a batch type mixer. One pound of the hindered piperidine substituted 2-hydroxy-benzophenone shown in drawing 1 is added, followed by 0.2 pounds of red pigment. After mixing for five minutes at 190 degrees C, the flux is pelletized, and resulting pellets are fed to an injection molding machine in which eight inch plastic toy shovels are made. In the preferred mode, all of the above steps are carried out under a nitrogen blanket to inhibit oxidative degradation during processing and fabrication.