Temperature-controlled induction heating of polymeric materials

• US 20090127253A1
• Filed: 05/13/2008
• Published: 05/21/2009
• Est. Priority Date: 06/06/1997
• Status: Abandoned Application

• Current Assignee: Guy Rossi, Hamid Mojazza, Peter Schuler, Philip Stark, Ross Haghighat
• Original Assignee: Guy Rossi, Hamid Mojazza, Peter Schuler, Philip Stark, Ross Haghighat
• Inventors: Schuler, Peter, Haghighat, Ross, Rossi, Guy, Stark, Philip, Mojazza, Hamid
• Application Number:
  US12/152,258
• Publication Number:
  US 20090127253A1
• Time in Patent Office: Days
• US Class Current: 219/660
• CPC Class Codes: B29C 2035/0811 using induction
• CPC Class Codes: B29C 2035/0816 using eddy currents
• CPC Class Codes: B29C 2043/185 using adhesives
• CPC Class Codes: B29C 35/0272 using lost heating elements, i.e. heating means incorporated and remaining in the formed article for preforms with internal stresses B29C61/0625; joining using lost heating elements B29C65/34; making electrically conductive articles B29C70/882
• CPC Class Codes: B29C 35/08 by wave energy or particle radiation B29C64/00, B29C71/04 take precedence
• CPC Class Codes: B29C 43/003 characterised by the choice of material
• CPC Class Codes: B29C 43/203 Making multilayered articles
• CPC Class Codes: B29C 65/3612 comprising fillers
• CPC Class Codes: B29C 65/3696 with a coating
• CPC Class Codes: B29C 66/71 characterised by the composition of the plastics material of the parts to be joined welding bar compositions B29C65/125
• CPC Class Codes: B29C 66/73756 the to-be-joined areas of both parts to be joined being fully cured
• CPC Class Codes: B29C 66/7392 characterised by the material of at least one of the parts being a thermoplastic
• CPC Class Codes: B29C 66/73921 characterised by the materials of both parts being thermoplastics
• CPC Class Codes: B29C 66/7394 characterised by the material of at least one of the parts being a thermoset
• CPC Class Codes: B29C 66/73941 characterised by the materials of both parts being thermosets
• CPC Class Codes: B29C 66/91216 enabling contactless temperature measurements, e.g. using a pyrometer
• CPC Class Codes: B29C 66/91218 using colour change, e.g. using separate colour indicators
• CPC Class Codes: B29C 66/91221 of the parts to be joined
• CPC Class Codes: B29C 66/91411 of the parts to be joined, e.g. the joining process taking the temperature of the parts to be joined into account
• CPC Class Codes: B29C 66/91443 following a temperature-time profile B29C65/38 takes precedence
• CPC Class Codes: B29C 66/91445 : by steps
• CPC Class Codes: B29C 66/91651 : by controlling or regulating the heat generated by Joule heating or induction heating
• CPC Class Codes: B29C 66/919 : characterised by specific temperature, heat or thermal flux values or ranges specific electrical resistance values B29C66/81262
• CPC Class Codes: B29C 66/9192 : in explicit relation to another variable, e.g. temperature diagrams
• CPC Class Codes: B29C 66/91921 : in explicit relation to another temperature, e.g. to the softening temperature or softening point, to the thermal degradation temperature or to the ambient temperature
• CPC Class Codes: B29C 66/91933 : higher than said fusion temperature
• CPC Class Codes: B29C 66/91935 : lower than said fusion temperature
• CPC Class Codes: B29C 66/91951 : in explicit relation to time, e.g. temperature-time diagrams
• CPC Class Codes: B29K 2023/04 : Polymers of ethylene
• CPC Class Codes: B29K 2023/06 : PE, i.e. polyethylene
• CPC Class Codes: B29K 2023/065 : HDPE, i.e. high density polyethylene
• CPC Class Codes: B29K 2023/086 : EVOH, i.e. ethylene vinyl alcohol copolymer
• CPC Class Codes: B29K 2023/12 : PP, i.e. polypropylene
• CPC Class Codes: B29K 2025/00 : Use of polymers of vinyl-aromatic compounds or derivatives thereof as moulding material
• CPC Class Codes: B29K 2063/00 : Use of EP, i.e. epoxy resins or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2067/00 : Use of polyesters or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2067/003 : PET, i.e. poylethylene terephthalate
• CPC Class Codes: B29K 2069/00 : Use of PC, i.e. polycarbonates or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2071/00 : Use of polyethers , e.g. PEEK, i.e. polyether-etherketone or PEK, i.e. polyetherketone or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2071/12 : PPO, i.e. polyphenylene oxide; PPE, i.e. polyphenylene ether
• CPC Class Codes: B29K 2075/00 : Use of PU, i.e. polyureas or polyurethanes or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2077/00 : Use of PA, i.e. polyamides, e.g. polyesteramides or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2079/085 : Thermoplastic polyimides, e.g. polyesterimides, PEI, i.e. polyetherimides, or polyamideimides; Derivatives thereof
• CPC Class Codes: B29K 2081/04 : Polysulfides, e.g. PPS, i.e. polyphenylene sulfide or derivatives thereof
• CPC Class Codes: B29K 2081/06 : PSU, i.e. polysulfones; PES, i.e. polyethersulfones or derivatives thereof
• CPC Class Codes: B29K 2101/10 : Thermosetting resins
• CPC Class Codes: B29K 2101/12 : Thermoplastic materials
• CPC Class Codes: B29K 2105/0854 : in the form of a non-woven mat
• CPC Class Codes: B29K 2105/203 : Magnetic parts
• CPC Class Codes: B29K 2105/24 : crosslinked or vulcanised
• CPC Class Codes: B29K 2303/06 : Metal powders, metal carbides or the like
• CPC Class Codes: B29K 2995/0008 : Magnetic or paramagnetic
• CPC Class Codes: B29L 2031/712 : Containers; Packaging elements or accessories, Packages closures therefor B29L2031/56; ink or toner cartridges B29L2031/7678; squeeze tubes B29L2023/20; suitcases B29L2031/7418
• CPC Class Codes: B29L 2031/7172 : Fuel tanks, jerry cans
• CPC Class Codes: C08K 3/22 : of metals

Abstract

The present invention provides new polymer induction bonding technology. Induction heating technologies are utilized to weld, forge, bond or set polymer materials. The invention provides controlled-temperature induction heating of polymeric materials by mixing ferromagnetic particles in the polymer to be heated. Temperature control is obtained by selecting ferromagnetic particles with a specific Curie temperature. The ferromagnetic particles will heat up in an induction field, through hysteresis losses, until they reach their Curie temperature. At that point, heat generation through hysteresis loss ceases. This invention is applicable to bonding thermoplastic materials, wherein only the area to be heated has ferromagnetic particles in it; bonding of thermoset composites, which have been processed with a layer of thermoplastic material on one side; curing of thermoset adhesives or composite resins; or consolidating thermoplastic composites.

Claims

1. An apparatus for controlling induction heating a thermoplastic material comprising:

at least one matrix material;

ferromagnetic, electrically non-conductive hexagonal ferrite particles having the composition SrFe₁₂O₁₉, Me_a-2W, Me_a-2Y, and Me_a-2Z, wherein 2W is BaO;

2 Me_aO;

8Fe₂O₃, 2Y is 2(BaO;

Me_aO;

3Fe₂O₃), and 2Z is 3BaO;

2 Me_aO;

12Fe₂O₃, and wherein Me_a is a divalent cation, or magnetically soft ferrite particles having the composition 1Me_bO;

1Fe₂O₃, where Me_bO is a transition metal oxide, wherein the particles have a specific Curie temperature (T_c), and wherein the particles are in contact with the thermoplastic material;

an inductor for heating the particles to their Curie temperature; and

a power source connected to the inductor.

2. The apparatus of claim 1, wherein the particles are from about 1 micron to about 840 microns.

3. The apparatus of claim 1, wherein the particles are less than 1 micron.

4. The apparatus of claim 1, wherein the power source provides an alternating field of from about 500 KHz to about 10 MHz to the inductor, and wherein the frequency of the field is selected to optimize the efficiency and rate of heating during the bonding or curing process.

5. The apparatus of claim 1, wherein T_c of the particles is less than the melting temperature of the thermoplastic material.

6. The apparatus of claim 1, wherein T_c of the particles is greater than the melting temperature of the thermoplastic material.

7. The apparatus of claim 1, wherein Me_a comprises Mg, Co, Mn or Zn and Me_b comprises Ni, Co, Mn, or Zn.

8. The apparatus of claim 1, wherein the particles comprise SrFe₁₂O₁₉, Co-2Y, Mg-2Y, Zn/Co-2Y, or Zn/Mg-2Y or combinations thereof, (Mn, ZnO)Fe₂O₃ or (Ni, ZnO)Fe₂O₃.

9. The apparatus of claim 1, wherein the thermoplastic material comprises a shaped polymeric material.

10. The apparatus of claim 9, further comprising a layer of distinct material laminated to the shaped polymeric material.

11. The apparatus of claim 1, wherein the thermoplastic material comprises PEEK, PEKK, PEI, PPS, PSU, PET, polyester, PA, PP, PE, PU, PPO, PC or combinations thereof.

12. The apparatus of claim 9, wherein the polymeric material is shaped by extrusion or compression molding or by a film casting process.

13. The apparatus according to claim 1, wherein the ferromagnetic particles are embedded in the surface of the thermoplastic material.

14. The apparatus according to claim 1, wherein the ferromagnetic particles are dispersed throughout the thermoplastic material.

15. The apparatus according to claim 1, wherein the inductor operates at a power between 1500 W-2300 W.

16. The apparatus according to claim 1, wherein the inductor has a frequency of 88 kHz-310 kHz.