Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1995-06-12
1998-01-13
Warzel, Mark L.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525316, C08L 2504, C08L 5502, C08L 900
Patent
active
057080810
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention relates to polymer compositions comprising a vinylaromatic polymer and a rubber. These compositions are easy to process and exhibit good gloss and excellent mechanical properties.
They find applications in fields as diverse as electrical household appliances, that of office equipment or packaging.
PRIOR ART
Various techniques for improving the impact strength of compositions based on vinylaromatic polymer and rubber have been proposed.
Document EP 418,042 teaches an impact polystyrene composition comprising a branched polybutadiene exhibiting a double distribution of molecular masses, the ratio of the mean molecular masses of the component of high masses to that of low masses being higher than a factor of 2.5 and preferably between 3 and 5. The component of high molecular masses corresponds to branched molecules, while the component of low molecular masses corresponds to incompletely branched molecules. The polybutadiene has a cis-1,4 structure content which is preferably lower than 70% and more preferably lower than 50%.
The impact polystyrenes thus obtained have a marked bimodal structure and the distribution of their particle diameters indicates the presence of three distinct particle populations.
Document JP 4-100810 teaches the use of a mixture of two polybutadienes exhibiting very different viscosities. One of these polybutadienes must exhibit an intrinsic viscosity of between 3 and 7 dl/g, whereas the other polybutadiene must exhibit an intrinsic viscosity of between 0.5 and 1.4 dl/g. The use of such polybutadienes exhibits limits. In fact, the manufacture of a polybutadiene whose intrinsic viscosity is close to 7 dl/g is difficult to carry out. In addition, if the viscosity of the second polybutadiene is close to 1.4 dl/g, the viscosity of the polymer solution, which also contains the first polybutadiene of particularly high viscosity, becomes too high.
DESCRIPTION OF THE INVENTION
Polymer compositions comprising a vinylaromatic polymer and a rubber have now been found, the said rubber being derived from a high-viscosity polybutadiene and from a low-viscosity polybutadiene, the intrinsic viscosities of these two polybutadienes being close but different and such that that of the high-viscosity polybutadiene is lower than 3 dl/g and that of the low-viscosity polybutadiene is higher than 1.4 dl/g. The term rubber denotes the elastomeric phase present in the composition according to the invention.
This elastomeric phase contains all the mass of the polybutadienes initially introduced. The rubber of the compositions according to the invention therefore contains polybutadiene which my be partially crosslinked or grafted onto the vinylaromatic polymer. This rubber forms the shell of particles containing a proportion of the vinylaromatic polymer, the said particles themselves being dispersed in a matrix of vinylaromatic polymer.
The use of the two polybutadienes, of high and low viscosity, produces polymer compositions with remarkable mechanical properties, in particular with regard to the impact strength. These properties are generally superior to those obtained by employing only one of these polybutadienes, with an appreciably identical polybutadiene content and with an appreciably identical degree of grafting of the polybutadiene with the vinylaromatic polymer in the polymer compositions being considered.
Furthermore, a polymer composition according to the invention exhibits an impact strength which is higher than the arithmetic mean of the impact strengths of the compositions obtained, on the one hand, with the high-viscosity polybutadiene by itself and, on the other hand, with the low-viscosity polybutadiene by itself, this being at a polybutadiene content which is appreciably identical and with an appreciably identical degree of grafting of polybutadiene with vinylaromatic polymer in the polymer compositions being considered.
This is reflected in the fact that if invention, in which the rubber is derived from a high-viscosity polybutadiene X and from a low-viscosi
REFERENCES:
English translation of JP4100810, Apr. 2, 1992.
Japan Synthetic Rubber, WPI AN 90-331461 (1990).
Jenkins Thomas Edward
Sarraf Tarek
Elf Atochem S. A.
Warzel Mark L.
LandOfFree
Composition comprising a vinylaromatic polymer and a rubber and does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Composition comprising a vinylaromatic polymer and a rubber and , we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Composition comprising a vinylaromatic polymer and a rubber and will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-327182