Claims
- 1. A typewriter lift-off tape for removing typed ink impressions comprising a non-adhesive backing layer and a normally non-tacky elastic adhesive layer on one major surface of the backing layer, said backing layer being relatively inextensible and said adhesive layer being relatively extensible; wherein in said tape, the adhesive layer
- (1) comprises an adhesive composition consisting essentially of
- (a) thermoplastic and elastomeric A-B block copolymers in which
- (i) the A-blocks are thermoplastic being derived from styrene or styrene homologs, possess a number average molecular weight of at least about 6,000, and constitute about b 5 to about 50 percent by weight of the block copolymer, and
- (ii) the B-blocks are elastomeric being derived from conjugated dienes or lower alkenes and possess a number average molecular weight in the range of about 45,000 to 180,000, and
- (b) normally solid resins adapted to associate principally with the thermoplastic A-blocks of said copolymers, said resins being employed in an amount of from about 40 to about 90 parts by weight per 100 parts by weight of the block copolymer; and
- (2) exhibits a plastic state at low elongations and an elastic state at high elongations, and has the property of being converted from a normally non-tacky and plastic state to a tacky and elastic state when struck by a typewriter key.
- 2. A typewriter lift-off tape according to claim 1, wherein the backing layer is a polyester film.
- 3. A typewriter lift-off tape according to claim 1, wheren the adhesive composition contains about 30-90 parts per 100 parts by weight of the block copolymers of the A-block associating resins.
- 4. A typewriter lift-off tape according to claim 1, wherein said normally solid resins consist essentially of resins selected from the group consisting of alpha-metylstyrene-vinyltoluene copolymers and coumarone-indene copolymers.
- 5. A tacky adhesive film or a film having a tacky adhesive portion, said film obtained by applying substantial mechanical stress in whole or in part to a non-tacky adhesive film having a composition consisting essentially of
- (a) thermoplastic and elastomeric A-B block copolymers in which (i) the A-blocks are thermoplastic being derived from styrene or styrene homologs, possess a number average molecular weight of at least about 6,000, and constitute about 5 to about 50 percent by weight of the block copolymer, and (ii) the B-blocks are elastomeric being derived from conjugated dienes or lower alkenes and possess a number average or molecular weight in the range of about 45,000 to 180,000, and
- (b) normally solid resins adapted to associate principally with the thermoplastic A-block of said copolymers, said resins being employed in an amount of from about 20 to about 120 parts per 100 parts by weight of the block copolymer.
- 6. An adhesive tape comprising a non-adhesive backing layer and a tacky adhesive layer on one major surface of the backing layer, said tape prepared by
- (1) extruding to a film, a composition consisting essentially of
- (a) thermoplastic and elastomeric A-B block copolymers in which (i) the A-blocks are thermoplastic being derived from styrene or styrene homologs, possess a number of average molecular weight of at least about 6,000 and constitute about 5 to about 50 percent by weight of the block copolymer and (ii) the B-blocks are elastomeric being derived from conjugated diene or lower alkene and possess a number average molecular weight in the range of about 45,000 to 180,000, and
- (b) normally solid resins adapted to associate principally with the thermoplastic A-blocks of said copolymer, and resins being employed in an amount of from about 20 to 120 parts by weight per 100 parts by weight of the block copolymer;
- (2) stretching said film to convert it from a normally non-tacky and plastic state to a tacky and elastic state;
- (3) allowing the tacky stretched film to relax; and
- (4) laminating said film to the backing layer.
Parent Case Info
This is a division of application Ser. No. 820,677, filed Aug. 1, 1977, now U.S. Pat. No. 4,166,706.
US Referenced Citations (11)
Foreign Referenced Citations (1)
Number |
Date |
Country |
2550487 |
May 1977 |
DEX |
Non-Patent Literature Citations (2)
Entry |
Shell Bulletin, SCR:67-182, Oct. 1967, pp. 10, 12 and 13. |
Shell Bulletin, SCR:72-3, Aug. 1972, pp. 4, 5 and 19. |
Divisions (1)
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Number |
Date |
Country |
Parent |
820677 |
Aug 1977 |
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