Composite ballistic resistant laminate

A method of making an impact penetration resistant laminate comprising the steps of

• (i) providing a plurality of cross-plied non-fibrous ultra-high molecular weight polyethylene sheets wherein the polyethylene sheet comprises two monolayers of polyethylene oriented film separated by an adhesive arranged such that the orientation of one monolayer in the sheet is offset with respect to the orientation of the other monolayer in the sheet, wherein the adhesive has a basis weight of no greater than 5 gsm and a zero-shear-rate viscosity, determined from an oscillating disc rheometer in a frequency sweep between 0.1 rad/s and 100 rad/s, conducted per ASTM D 4440 at 125° C., and calculated from fitting to a Carrea-Yasuda four parameter model, of at least 1500 Pa-s,
• (ii) assembling a stack comprising a plurality of UHMWPE sheets of step (i) in an arrangement wherein at least 90 percent of the sheets are positioned such that the orientation of a monolayer of one sheet is offset with respect to the orientation of the closest monolayer of an adjacent sheet and the combined weight of polyethylene sheets and adhesive in the stack is from 0.6-600 kg/m2,
• (iii) subjecting the stack of step (ii) to a pressure of from 10 to 400 bar and a temperature of from 70 to 150 degrees C. for between 5 and 60 minutes, and wherein the pressure loss on the stack is no greater than 35 bar within the first two minutes and no greater than 70 bar within the first 5 minutes as measured according to Test Method B to form the laminate, and
• (iv) cooling the laminate to a temperature of 50 degrees C. or less.