| 摘要 |
#CMT# #/CMT# The use as a self-sealing composition for pneumatic objects,of an elastomer composition (I) containing a thermoplastic styrene elastomer (TPS) as the major elastomer component and an extender oil in amounts of 200-700 phr (parts by weight per 100 parts rubber). #CMT# : #/CMT# Independent claims are also included for (1) an airtight anti-bursting laminate,especially for pneumatic objects,comprising an anti-bursting layer containing (I) and an airtight layer (2) a method for protecting a pneumatic object against bursting,by incorporating an anti-bursting layer containing (I) or a laminate as above in the object during fabrication or by adding such a layer or laminate afterwards (3) pneumatic objects containing (I) or a laminate as above . #CMT#USE : #/CMT# For the production of anti-bursting,self-sealing layers in pneumatic objects such as rubber boats,balloons,balls for sports and games,and especially tyres for motor vehicles or bicycles. #CMT#ADVANTAGE : #/CMT# A self-sealing composition showing better performance than prior-art compositions,based on a simplified formulation containing neither butyl rubber (large hysteresis loss over a wide range of temperature; inadequate sealing after removing perforating objects,especially in winter temperatures) nor tackifying resin (extra cost; adverse effect on rolling resistance). #CMT#DESCRIPTION OF DRAWINGS : #/CMT# The drawing shows a radial section of a pneumatic tyre (1) incorporating an anti-bursting laminate according to the invention. 10 : multi-layer laminate 10a : self-sealing,anti-bursting layer based on thermoplastic styrene elastomer plus extender oil 10b : airtight layer based on butyl rubber 11 : internal cavity. #CMT#POLYMERS : #/CMT# Preferred Materials: The TPS comprises block copolymers based on styrene (S) and butadiene (B),isoprene (I),ethylene (E),butylene (B') and/or propylene (P),e.g. SBS,SIS,SIBS,SEB'S,SEPS and/or SEEPS,especially SEB'S and/or SEPS. The TPS has a styrene content of 5-50 (preferably 15-35) wt.%,a glass transition point (Tg) below -20[deg] C and a number-average molecular weight (M n) of 50000-500000,preferably 250000-400000. Extender oils comprise polyolefins,paraffins,naphthenic oils,aromatic oils and/or mineral oils,especially polybutenes and/or paraffins,preferably polybutenes,with an M n of 200-30000,preferably 350-4000; the oil content of (I) is 250-600 (preferably 300-500) phr. (I) is used in the form of an anti-bursting layer with a thickness of more than 0.3 (preferably 0.5-10) mm,which is deposited on the internal wall of a pneumatic object,preferably a rubber object,especially a pneumatic tyre. This anti-bursting layer is combined with a butyl rubber-based airtight layer with a thickness of more than 0.05 (preferably 0.1-10) mm,so as to form a laminate inside an object such as a pneumatic tyre as above.Preferred Method: The anti-bursting layer or the airtight laminate is laid flat on a production drum and then covered with the rest of the tyre structure.Preferred Objects: Pneumatic rubber tyres. #CMT#EXAMPLE : #/CMT# A tourist-type pneumatic tyre (205/55 R16) with an internal airtight layer was modified by covering this layer with a 2-mm layer of Mediprene 500000M (RTM: oil-extended thermoplastic elastomer) and then vulcanised. The inflated tyre was pierced through the tread block and the sides with 5 holes of diameter 6 mm and 2 holes of diameter 1 mm,using awls which were then immediately pulled out. The pierced tyre (mounted on a wheel) was driven for more than 6300 km at 130 km/hour under a nominal load of 400 kg without losing pressure. A similar result was obtained if the perforating awls were left in place for a week. |
