1 2
In one aspect, this invention is an article adapted for
REMOVABLE HEATING ARTICLE FOR USE IN providing heat to a substrate in an alternating magnetic
ALTERNATING MAGNETIC FIELD field comprising in combination:
a base material; and
RELATED APPLICATIONS 5 lossy heating particles carried by the base material
This application is a continuation-in-part of U.S. Ser. whi,_ch Particles have a Curie temperature at least equal
No. 07/242,208 filed Sept. 9, 1988 now abandoned and to 'he temperature to which the substrate is to be heated
is a continuation-in-part of U.S. Ser. No. 07/404,621 ««d which have sufficiently high permeability and are
filed SeDt 8 1989 sufficiently highly lossy to produce the desired heat
10 when subjected to an alternating magnetic field,
FIELD OF THE INVENTION wherein the base material carrying the particles is
This invention relates to articles, methods and sys- adaPted l° placed on a surface of the substrate for
terns for providing heat to selected substrates by sub- heatIng the ^bstrate and is adapted for removal of the
jecting the substrate and a removable article comprising 15 Pmfes from the ^strate after heating the substrate in
magnetic particles to an alternating magnetic field. an alternating magnetic field.
In one preferred aspect of this invention, the above
BACKGROUND OF THE INVENTION article is adapted to be removably placed on the sub
-m. r r i j i_ strate and is removed from the substrate after the de
The use of fernte particles to produce heating in ......
.. .. .. _ ,, . , . . . j. sired heating has been accomplished, thereby removing
alternating magnetic fields is known in the art. As dis- m „ . • , r i_ .
closed in U.S. Pat. No. 3,391,846 to White, and U.S. Pat. the particles from the substrate.
No. 3,902,940 to Heller et al., ferrite particles have been „In Preferred .asP?? °L thls ,nvent,°n' the ', . * . .'. . , • above article is provided with adhesive means for reused to produce heat where it is desired to cause chemi- ,. ,, .r ., . , - - . ,
. . . • i i movably adhering the article to a surface of the base cal reactions, melt materials, evaporate solvents, pro- . :, , , °, ... , .. , , , duce ases and for other u oses 25 matena' whereby the article can be applied to the subtil??6!' an . 0r ... /nwno /a v strate to be heated, then the particles removed from the PCT International Publication WO84/02098 (Apph- e . . . ,., , .. , , . XT .„.«. t Ji Vfc. surface of the base material after the heating has been cation No. PCT/US83/01851 corresponding to the U.S. , , r , , ,. ...f ,. ., TM Vt I-i t. r accomplished, for example, by washing with a liquid. Pat. No. 4,914,267) of Derbyshire discloses the use of Ifl ... feTTJ Jct of thif inventioJ the
ferromagnetic materials having the desired Curie tern- h m ^ form of a havJ at ^ m%
perature in electrically conductive layers to provide 30 ^ ^ fe ^ ferabJ a j.
auto-regulated heating to the Cune temperature of the havm at ^ 2QQ% d ti which ovides the
material upon application of an alternating current to artide the c biHt of bein stretched onto a substrate
the conductive layer of ferromagnetic material. The for heatin fa m a,ternati m netic field so that the
power applied to the ferromagnetic layer is in the form win ch dimension with the substrate when it
of an alternating current source which produces skin ch dimension or shape when heated) such as heat
effect or eddy current heating m the continuous ferro- recoverable substrates
magnetic layer. As the ferromagnetic layer reaches the In another preferred aspect of this invention, the Curie temperature, the permeability of the layer drops magnetic particles present in the article comprise a and the skin depth increases, thereby spreading the ^ combination of lossy heating particles for producing current through the wider area of the ferromagnetic heat and non_iossy particles for providing consistent or layer until the Cune temperature is achieved through- improved magnetic circuit coupling during heating, out and the desired heating is achieved. In another aspect, this invention is a method of heatIn my copending applications referred to above and jng a substrate comprising: incorporated herein by reference, I disclose the use of 45 placing on a surface of the substrate an article cornmagnetic particles in combination with heat-recovera- prising a base material and lossy heating particles carble articles in alternating magnetic fields to effect recov- rjed by the base material which particles have a Curie ery. In connection with those systems, I have observed temperature at least equal to the temperature to which that it would be desirable to have a different form of the substrate is to be heated and which have sufficiently self-regulating, self-heating articles which can be used 50 high permeability and are sufficiently highly lossy to more conveniently in some applications to heat various produce the desired heat when subjected to an alternatsubstrates and materials. ing magnetic field wherein the article is adapted to Therefore, it is an object of this invention to provide provide removal of the particles after heating the suban improved article and an improved system for provid- strate;
ing heat to substrates using alternating magnetic fields. 55 subjecting the substrate having said article on a sur
SUMMARY OF THE INVENTION It^l^f u° TM *ieTMf»STMen«ic field to Produce
the desired heating of the substrate; and
I have now found that the above objects and other removing the article from the substrate, utilities and benefits can be achieved by providing an In another aspect, this invention is a system for heatarticle which can be placed on the surface of the sub- 6fj ing a substrate comprising, in combination: strate to be heated wherein the article comprises lossy a substrate to be heated;
heating particles which produce the desired heat and an article on a surface of the substrate comprising a
accomplish the heating of the substrate when subjected base material and lossy heating particles carried by the
to an'alternating magnetic field, wherein the article is base material which particles have a Curie temperature
adapted to provide removal of the particles from the 65 at least equal to the temperature to which the substrate
substrate, after heating the substrate either by removing is to be heated and which have sufficiently high permea
the article carrying the particles or by removing the bility and are sufficiently highly lossy to produce the
particles from the article. desired heat when subjected to an alternating magnetic
