Marker for a magnetic theft protection system and method for its production

1. A marker for a magnetic theft protection system, comprising:

(a) at least one oblong alarm strip comprising an amorphous ferromagnetic alloy; and

(b) at least one oblong activation strip consists essentially of a molybdenum-free semi-hard magnetic alloy of formula Ni a M b Fe Rest , wherein M is one or more of the elements selected from the group consisting of Cr, W and V, and wherein a and b are weight percentages, such that 15% by weight ≦a≦25% by weight, and 2% by weight ≦b≦8% by weight, and wherein said activation strip has a coercive force H c of 10 A/cm to 25 A/cm and a remanence B r of at least 0.9 T.

2. The marker according to claim 1 ,

wherein said remanence B r is at least 1.1 T.

3. The marker according to claim 1 ,

wherein said coercive force H c is between 14 A/cm and 20 A/cm.

4. The marker according to claim 1 ,

wherein b is a weight percentage such that 4% by weight ≦b≦8% by weight.

5. A tag comprising a marker according to claim 1 .

6. The tag according to claim 5 ,

further comprising a housing enclosing said marker.

7. The tag according to claim 6 ,

further comprising a layer of adhesive applied to at least one side of said housing.

8. An article comprising a marker according to claim 1 .

9. An article comprising a tag according to claim 5 .

10. The article of claim 8 , wherein said article comprises a consumer product or packaging for a consumer product.

11. A method for the production of an activation strip for a marker for a magnetic theft protection system that comprises at least one oblong alarm strip comprising an amorphous ferromagnetic alloy, and at least one oblong activation strip, said method comprising:

(a) melting a molybdenum-free semi-hard magnetic alloy consisting essentially of Ni a M b Fe Rest , wherein M is one or more of the elements from the group including Cr, W and V, and wherein a and b are weight percentages, such that 15% by weight ≦a≦25% by weight, and 2% by weight ≦b≦8% by weight, in a vacuum or an inert gas atmosphere;

(b) casting said melted alloy to produce an ingot;

(c) hot forming of said ingot at temperatures above approximately 800° C. to produce a first strip;

(d) process annealing of said first strip at a temperature of approximately 1100° C. to form an annealed first strip;

(e) rapidly cooling said annealed first strip to form a cooled annealed first strip;

(f) cold forming said cooled annealed first strip to a reduction in cross-section of approximately 65% to form a second strip;

(g) process annealing said second strip at a temperature of approximately 650° C. to form an annealed second strip;

(h) cold forming said annealed second strip to reduce cross-section to form a third strip, wherein the reduction in cross-section is selected such that said third strip has a remanence B r >0.9 T; and

(i) tempering said third strip at a defined temperature and for a defined time, said temperature and time being selected to produce an activation strip having a coercive force H c of 10 A/cm to 25 A/cm.

12. The method according to claim 11 ,

said cold forming of said annealed second strip corresponds to a reduction in cross-section of at least 80%.

13. The method according to claim 11 ,

wherein said tempering is carried out at a temperature between 425° C. and 525° C.

14. The method according to claim 11 , further comprising cutting said activation strips to length.

15. The method according to claim 11 , wherein b is a weight percentage such that 4% by weight ≦b≦8% by weight.

16. The method according to claim 11 , wherein said remanence B r >1.1 T.

17. The method according to claim 16 , wherein said remanence B r >1.3 T.

18. The method according to claim 11 , wherein said coercive force H c is 14 A/cm to 20 A/cm.

19. The method according to claim 11 , wherein said reduction in cross-section is at least 90%.

20. The method according to claim 11 , wherein said reduction in cross-section is at least 95%.

21. A method for the production of a marker for a magnetic theft protection system, comprising:

(a) providing at least one oblong alarm strip comprising an amorphous ferromagnetic alloy;

(b) providing at least one oblong activation strip consisting essentially of a molybdenum-free semi-hard magnetic alloy having formula Ni a M b Fe Rest , wherein M is one or more of the elements from the group including Cr, W and V, and wherein a and b are weight percentages, such that 15% by weight ≦a≦25% by weight, and 2% by weight ≦b≦8% by weight, and wherein said activation strip has a coercive force H c of 10 A/cm to 25 A/cm and a remanence B r of at least 0.9 T; and

(c) placing said at least one oblong alarm strip on said at least one oblong activation strip to produce said marker.

22. The method according to claim 21 ,

further comprising locating said oblong alarm strip and said oblong activation strip of said marker in a housing.

23. The method according to claim 21 ,

further comprising locating said oblong alarm strip and said oblong activation strip of said marker in a packaging of a consumer product.

24. An oblong activation strip suitable for a marker for a magnetic theft protection system, comprising an alloy consisting essentially of a molybdenum-free semi-hard magnetic alloy of formula Ni a M b Fe Rest , wherein M is one or more of the elements selected from the group consisting of Cr, W and V, and wherein a and b are weight percentages, such that 15% by weight ≦a≦25% by weight, and 2% by weight ≦b≦8% by weight, and wherein said activation strip has a coercive force H c of 10 A/cm to 25 A/cm and a remanence B r of at least 0.9 T.