Process for coating to form a foam find protective package

A method of producing a packaging material particularly for use in making heat sealable protective envelopes, said packaging material consisting of an outer paper substrate, an aqueous based heat sensitizable coating applied to one surface of said substrate and a foamed polymeric material of cellular structure adhered to substantially the entire area of the coated surface of said substrate comprising:

• a. forming an aqueous coating of powdered polyethylene and a copolymer of ethylene and acrylic acid, said coating comprising from about 30 to 100 parts of a copolymer consisting of from about 70-85% ethylene and from about 30-15% acrylic acid and up to about 70 parts of a powdered polyethylene material having a particle size in the range of from about 10-30 microns, said coating having a solids content of from about 25 to 45%;
• b. applying a continuous film of said coating uniformly to one surface of a paper substrate to produce a coat weight of at least about 3 pounds per ream;
• c. drying said coating;
• d. adhering a polyethylene foam material to substantially the entire area of the coated surface of said substrate under the influence of heat and pressure while leaving portions of said coating surface exposed to be heat sealed to themselves;
• and,
• e. heat sealing said exposed surfaces to one another to form a foam lined protective envelope.