Method of heat sealing employing a hot tack adhesive

In a method of forming a seal or bond between facing substrate surfaces having a heat-activatable thermoplastic adhesive material therebetween by applying pressure sufficient to maintain intimate contact between the adhesive material and the substrate surfaces and heating to a temperature in the heat-seal range to activate the thermoplastic adhesive material in the area to be sealed or bonded, wherein the resulting seal or bond is subjected to force tending to separate the substrate surfaces while the adhesive material therebetween is at a temperature in the heat-seal range,

• the improvement wherein the heat-activatable thermoplastic adhesive material is composed essentially of a copolymer of ethylene and at least one acid selected from acrylic acid and methacrylic acid, which copolymer contains from about 6 to about 10 weight percent of said acid based on the copolymer and has melt flow value in the range from about 1 to about 3 dg/min., whereby the resulting seal or bond has high hot tack strength.