A composite film comprising: a) a self-supporting layer of a polymer film (optionally the polymer film comprising a polar polymer and/or a polyolefin polymer) and further optionally oriented in at least one direction, b) an optional primer layer on the polymer film, and in between the polymer film and a heat seal layer (c), wherein the primer layer comprises a halo polyvinylidine polymer, an acrylic resin and/or a vinyl resin; and wherein the heat seal layer comprising a heat seal composition is either disposed on the optional primer layer where present, or directly on a surface of the polymer film in the absence of the optional primer layer (b), wherein the heat seal layer composition comprises a polyolefin plastomer resin and a tackifier; and where i. the tackifier is present in an amount of at least 20% by weight of the heat seal composition, the total weight of the heat seal composition being 100%; and ii. the POP resin is present in an amount of no more than 80% by weight of the heat seal composition, the total weight of heat seal composition being 100%; and where iii. the optional primer layer is only absent when the polymer film comprises polyolefin and where in the absence of the optional primer layer (b), the surface of the polymer film in contact with the heat layer (c) has been corona treated. a) a self-supporting layer of a polymer film (optionally the polymer film comprising a polar polymer and/or a polyolefin polymer) and further optionally oriented in at least one direction, b) an optional primer layer on the polymer film, and in between the polymer film and a heat seal layer (c), wherein the primer layer comprises a halo polyvinylidine polymer, an acrylic resin and/or a vinyl resin; and wherein the heat seal layer comprising a heat seal composition is either disposed on the optional primer layer where present, or directly on a surface of the polymer film in the absence of the optional primer layer (b), wherein the heat seal layer composition comprises a polyolefin plastomer resin and a tackifier; and where i. the tackifier is present in an amount of at least 20% by weight of the heat seal composition, the total weight of the heat seal composition being 100%; and ii. the POP resin is present in an amount of no more than 80% by weight of the heat seal composition, the total weight of heat seal composition being 100%; and where iii. the optional primer layer is only absent when the polymer film comprises polyolefin and where in the absence of the optional primer layer (b), the surface of the polymer film in contact with the heat layer (c) has been corona treated. wherein the heat seal layer comprising a heat seal composition is either disposed on the optional primer layer where present, or directly on a surface of the polymer film in the absence of the optional primer layer (b), wherein the heat seal layer composition comprises a polyolefin plastomer resin and a tackifier; and where i. the tackifier is present in an amount of at least 20% by weight of the heat seal composition, the total weight of the heat seal composition being 100%; and ii. the POP resin is present in an amount of no more than 80% by weight of the heat seal composition, the total weight of heat seal composition being 100%; and where iii. the optional primer layer is only absent when the polymer film comprises polyolefin and where in the absence of the optional primer layer (b), the surface of the polymer film in contact with the heat layer (c) has been corona treated. i. the tackifier is present in an amount of at least 20% by weight of the heat seal composition, the total weight of the heat seal composition being 100%; and ii. the POP resin is present in an amount of no more than 80% by weight of the heat seal composition, the total weight of heat seal composition being 100%; and where iii. the optional primer layer is only absent when the polymer film comprises polyolefin and where in the absence of the optional primer layer (b), the surface of the polymer film in contact with the heat layer (c) has been corona treated.