Thin film wrapping for cassette case
AssigneeSony Corporation
InventorSeizo Seki
Life of this patent
Estimating the term…
Abstract
A partly-overlapped portion of a sheath film is meltbonded by heat to provide a seal which a user can tear open with ease. A heat sealing area of the sheath film is halftone printed to reduce the bonding area, thereby decreasing the bonding strength. A tearing portion is provided along the heat seal which is printed so that it has a bonding strength which gradually increases along the tear part until it reaches the bonding strength of the remainder of the heat seal. A curl section having minimal bonding strength relative to the tearing portion of the heat seal is induced to curl up using heat treatment to allow the user to grasp the sheath film at the tear part.
Claims20
A packaging film comprising:
- a film of material capable of being formed as a substantially closed film envelope;
- tear means formed in said film said tear means including a tear part which is integral with said film and formed at a predetermined location in said film;
- a heat sealing area formed in said film, said heat sealing area corresponding to surfaces of the film which overlap during formation of said film envelope and between which a bond, having a predetermined bonding strength, is formed;
- at least one tearing portion extending along said heat sealing area from said tear part of said tear means;
- and
- means for modifying the bonding strength between the overlapping surfaces of said film along a predetermined length of said at least one tearing portion and for causing the bonding strength to gradually increase along said predetermined length away from the tear part of said tear means, from a minimum bonding strength, greater than or equal to zero, to said predetermined bonding strength.
A packaging envelope film comprising:
- tear means formed in a film of material, said tear means including a tear part which is integral with the film of material and formed at a predetermined location therein;
- a heat sealing area formed in the film of material, said heat sealing area corresponding to surfaces of the film of material which overlap during formation of said film envelope and between which a bond, having a predetermined bonding strength, is formed;
- at least one tearing portion leading from said tear part of said tear means and extending along said heat sealing area;
- means for modifying the bonding strength between the overlapping surfaces of the film of material along said at least one tearing portion and for causing the bonding strength to gradually increase away from the tear part of said tear means from a minimum bonding strength, greater than or equal to zero, to said predetermined bonding strength;
- and
- a readily grasped curled peel section formed in the film of material and connected to said tearing portion of said heat sealing area, said bonding strength bonding means modifying the bonding strength between overlapping surfaces of the film of material at said peel section to a level whereat said peel section curls when heat is applied.
Dependencies are inferred from the claim text.