Study On Preparation And Properties Of Silane Grafted α-Polyolefin Hot Melt Adhesive

Polyolefins hot melt adhesive with environmental protection,wide range of adhesive materials,weatherability good features such as widely used,especially the α-polyolefin hot melt adhesive,because its main chain containing long chain branch to improve the bonding strength of adhesive to the attention of the academia and industry,but its adhesive strength,heat resistance,etc,are still can not meet the demand of some areas,a need to add other viscosity resin,etc.,It limits its wide application in hot melt adhesive industry.In this paper,α-polyolefin with different molecular weights were grafted by silane to prepare hot melt adhesives without adding other components,in order to improve their applications in different fields.Specific research results are as follows:First,the process of grafting APAO-L and APAO-H with different molecular weightα-polyolefins with vinyl trimethoxysilane(VTMS)was studied.It is found that when the amount of VTMS is 5phr(parts added per 100 parts of resin by mass),the amount of dicumyl peroxide(DCP)is 0.2phr,the amount of antioxidant 1010 is 0.1 phr,and the reaction temperature is 180℃,the absorption ratio of APAO-L and APAO-H of grafted silane reaches the maximum.In addition,APAO-H with a wider molecular weight distribution is easier to graft silane,and the melting point before and after silane grafting APAO-H is much greater than that before and after APAO-L grafting.For APAO-L and APAO-H grafted with silane,T5wt%increased by 5℃ and 3℃,and T95wt%increased by 17℃ and 10℃,respectively.The thermal stability of α-polyolefin grafted with silane increased.Secondly,the wet curing process of α-polyolefin hot melt adhesives with different molecular weights grafted on silane was studied under two humidity conditions.For silane grafted APAO-L,after curing for 4 days,the hydrolysis crosslinking rate reached the maximum at 10%RH condition,but almost no longer hydrolyzed and crosslinked under 98%RH conditions.At 12 days,the curing degree was basically the same and no longer increased at the two humidity conditions.For silane grafting APAO-H,the hydrolysis crosslinking rate reached the maximum at 10%RH at 7 days,and the hydrolysis crosslinking rate was almost no longer at 98%RH at 15 days.The curing degree did not change at the two humidity conditions,and basically reached the same level at 19 days.For the wet curing process of silane grafted α-polyolefin hot melt adhesive,the curing degree of high humidity condition can be reached when the curing time is extended under low humidity condition,and the curing period of silane grafted APAO-H is slightly lagged under the same conditions.Finally,the bonding properties and bonding mechanism of α-polyolefin hot melt adhesives(APAO-L-5V,APAO-H-5V)grafted with silane with different molecular weights to different substrates were studied.Among them,the tensile shear strength and peel strength of APAO-L-5V were increased by 250%and 420%compared with that before grafting,and the tensile shear strength and peel strength of APAO-H-5V were increased by 160%and 320%,respectively,compared with that before grafting.The tensile shear strength of APAO-L-5V and APAO-H-5V increased by 160%and 270%,respectively,compared with that before grafting.The tensile shear strength and peeling strength of APAO-L-5V and APAO-H-5V were increased by 230%and 200%respectively compared with those before the grafting of PP,and the bonding effect of APAO-L-5V and APAO-H-5 V on the substrate was similar to that of the commercial polyolefin hot melt adhesive VP.Study on the bonding mechanism of silane grafted α-polyolefin hot melt adhesive shows that,on the one hand,during the wet curing process of silane grafted α-polyolefin hot melt adhesive,the grafted siloxane group on the polyolefin molecular chain is easy to hydrolyze to silanol and form hydrogen bonds with the polar groups such as hydroxyl groups on the surface of the substrate.On the other hand,under the hot melt pressure sizing condition,the polyolefin molecular crosslinking network formed in the wet curing process is compatible with the substrate or infiltrates into the surface of the substrate,thus enhancing the bonding effect of silane grafted α-polyolefin hot melt adhesive.