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A cross-laminate web is formed of two oriented films, the films being arranged so that the main direction of orientation of the first film (A) generally follows the longitudinal direction (D) of the web and the main direction of the second film (B) is perpendicular (F) to that direction. The coeffic

A cross-laminate web is formed of two oriented films, the films being arranged so that the main direction of orientation of the first film (A) generally follows the longitudinal direction (D) of the web and the main direction of the second film (B) is perpendicular (F) to that direction. The coefficient of elasticity of the material of the first film, in an unoriented state, is at least 115% lower than that of the material of the second film, and the heat shrinkability of the first film is greater than that of the second film. Bags formed from the cross-laminate have heat seals with improved shock peel strength.

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1. A cross-laminate in the form of an elongated web and consisting of two or more mutually bonded films or film assemblies, each of which is uniaxially oriented or unbalanced biaxially oriented, wherein said cross-laminate has on one of its sides a material A comprising either a) a film having a mai

1. A cross-laminate in the form of an elongated web and consisting of two or more mutually bonded films or film assemblies, each of which is uniaxially oriented or unbalanced biaxially oriented, wherein said cross-laminate has on one of its sides a material A comprising either a) a film having a main direction of orientation generally corresponding to the longitudinal direction of the web, or b) an assembly of films having a resultant main direction of orientation generally corresponding to said longitudinal direction, and on the other side a material (B) comprising either a) a film having a main direction of orientation generally perpendicular to the longitudinal direction of the web, or b) an assembly of films having a resultant main direction of orientation generally perpendicular to the longitudinal direction of the web, and the coefficient of elasticity (E) of the material A in its unoriented state is at least 15% lower than the coefficient of elasticity of the material B in its unoriented state and wherein upon heating the cross laminate, materials A and B exhibit differential shrinkability along the said longitudinal direction, A being more shrinkable. 2. A cross-laminate according to claim 1, wherein material A forms at least 10% by weight of the total cross-laminate, and that the shrinkabilities of materials A and B in the longitudinal direction of the web, each expressed in percentage terms, differ by at least 10% when the individual materials A and B are tested for their shrinkability in the longitudinal direction when heated to the same temperature, which is close to and below the lower of their mechanically determined melting points. 3. A cross-laminate according to claim 2, wherein the percentage of shrinkability of material A at the temperature defined in claim 2 is at least 30%. 4. A webformed cross-laminate according to claim 1 wherein the cross-section of the cross-laminate has a waved shape with stabilized waves. 5. A cross-laminate according to claim 4, wherein the wavelength measured from wave-top to wave-top on one surface of the cross-laminate is less than 5 mm. 6. A cross-laminate according to claim 1, wherein material B is composed of at least 2 generally symmetrically arranged films, each with a main direction of orientation forming an angle higher than 50° and lower than 90° to the longitudinal direction of the web. 7. A cross-laminate according to claim 1 wherein material A is composed of at least 2 generally symmetrically arranged films, each with a main direction of orientation forming an angle higher than 0° and lower than 35° to the longitudinal direction of the web. 8. A cross-laminate according to claim 1 in which materials A and/or B each comprises at least 2 films mutually bonded together, wherein the strength of said mutual bondings is greater than that of the bond between materials A and B. 9. A cross-laminate according to claim 1, wherein each of the films in both materials A and B is a coextruded film with an inner major layer for strength and exterior and intermediate minor layers on each side of said major layer, the compositions of the minor layers forming the surface of the laminate being selected for achieving desired surface properties and of the other minor layers being selected to facilitate the bonding of the films to each other. 10. A cross-laminate according to claim 9 wherein the main layer in each of the films which constitute material B consists essentially of high molecular weight high density polyethylene (HMWHDPE) or a blend of HMWHDPR and lineary low density polyethylene (LLDPE), and the main layer in each of the films which constitute material A consists essentially of LLDPE or a blend of LLDPE and HMWHDPE. 11. A cross-laminate according to claim 10, wherein between 5-20% polypropylene is added to the main layer in all films which constitute material B. 12. In a method of manufacturing a cross-laminate which comprises forming an elongated web made of a sandwich formed of different films, each exhibiting a main direction of orientation, and wherein these directions cross each other, subsequently further orienting the sandwiched films at a temperature below their melting range by stretching the same together in the longitudinal direction of the web, before or after this longitudinal stretching, also stretching the sandwiched films in the transverse direction of the web, this transverse stretching being carried out by passing the sandwiched films between grooved rollers, and bonding together the films in the sandwich to form a laminate before, during or after said longitudinal and transverse stretching operations, the improvement wherein said film sandwich consists of two materials (A′) and (B′), with material (A′) being situated on the one and material (B′) on the other side of the sandwich, material (A′) being either a) a film having a main direction of orientation generally corresponding to the longitudinal direction of the web, or b) an assembly of films having a resultant main direction of orientation generally corresponding to the said direction, and said orientation of material (A′) is stronger—as measured by shrink testing the materials (A′) and (B′) individually—than the orientation in material (B′) in the same direction, and material (B′) is either a) a film having a main direction of orientation generally perpendicular to the longitudinal direction of the web, or b) an assembly of films having a resultant main direction of orientation generally perpendicular to the longitudinal direction of the web, in which the coefficient of elasticity (E) of material (A′) in its unoriented state is at least 15% lower than the coefficient of elasticity of material (B′) in its unoriented state and said orientation of material (B′) is stronger—again measured for the materials individually—than the orientation in material (A′) in said perpendicular direction. 13. A method according to claim 12 wherein material (A′) forms at least 10% of the sandwich and the shrinkabilities of materials (A′) and (B′) in the longitudinal direction of the web, each expressed in percentage terms, differ by at least 10% according to a test in which the films within the individual materials are bonded together without change of their properties and are tested for their shrinkability in the longitudinal directed when heated to the same temperature, which is close to and below the lower of the mechanically determined melting points of the materials. 14. A method according to claim 12, wherein the orientation in material (A′) independently of material (B′) corresponding to the longitudinal direction of the web is made sufficiently strong to achieve that, in the final product, the percentage shrinkage of material (A′) as determined when material (A′) separately from material (B′) quickly is heated to the a temperature close to but below its mechanically determined melting point is no less than 30%. 15. A method according to claim 12 wherein each film of materials (A′) and (B′) is manufactured by coextrusion, and during such coextrusion is supplied on each side with a minor layer adapted to facilitate bonding of such film to an adjacent film in the laminate. 16. A method according to claim 12 wherein at least one of the films of material (A′), prior to the sandwiching of that material with material (B′) is oriented in the longitudinal direction by pulling the same against the frictional resistance of a roller or bar in contact therewith. 17. A method according to claim 16, wherein material (A)′ includes one film supplied with a mainly longitudinal melt orientation, and said one film is subjected to said pulling. 18. A method according to claim 16, wherein material (A′) comprises two film s which are produced each with a main direction of orientation at an angle higher than zero and lower than 45° to its longitudinal direction, the two films subsequently being assembled to form a generally symmetrical sandwich and this sandwich is subjected to the frictionally acting pulling. 19. A method according to claim 16, wherein material (A′) is produced by forming an elongated cross-laminate of 2 melt-oriented layers by coextrusion of such layers through counter-rotating die passages, laminating said 2 melt-oriented layers together immediately before or immediately after these layers have exited from said passages, preferably with a minor coextruded layer therebetween which is adapted to reduce bonding therebetween, the melt orientation in each of the 2 layers extending at an angle less than 45° to the longitudinal direction of this cross-laminate, and subsequently subjecting the resultant cross-laminate to longitudinal orientation by said pulling. 20. An article, such as a bag, made by heatsealing a length of the cross-laminate according to claim 1 to a length of a similar cross-laminate with a peel-type heatseal which extends generally perpendicularly to the longitudinal direction of said lengths, and in which material A of one cross-laminate is directly heatsealed to material A of the other cross-laminate. 21. A tubular or folded-over length of cross-laminate according to claim 1, adapted for manufacture of open-mouth bags or for form-and-fill bags or for form-fill-and seal bags, wherein material A forms the inner surface of the tube or folded-over length.