Magnetic polymer composite

• US 9,153,377 B2
• Filed: 02/08/2013
• Issued: 10/06/2015
• Est. Priority Date: 01/18/2008
• Status: Active Grant

• Current Assignee: Tundra Composites, LLC.
• Original Assignee: Tundra Composites, LLC.
• Inventors: Heikkila, Kurt E., Kroll, John S., Williams, Rodney K.
• Primary Examiner(s): Choi, Ling
• Assistant Examiner(s): WANG, CHUN CHENG
• Application Number:
  US13/762,714
• Publication Number:
  US 20130157053A1
• Time in Patent Office: 970 Days
• Field of Search: 524/494, 428/372, 264/299
• US Class Current: 1/1
• CPC Class Codes: B32B 5/16 characterised by features of a layer formed of particles, e.g. chips, powder or granules layer formed of natural mineral particles B32B19/00; layer being formed of wood fibres, chips or particles B32B21/02
• CPC Class Codes: C08K 3/08 Metals
• CPC Class Codes: C08K 7/20 Glass
• CPC Class Codes: H01F 41/00 Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
• CPC Class Codes: Y10T 428/2927 including structurally defined particulate matter

Abstract

The invention relates to a hot melt dispensable polymeric composite and process for making and using the composite. Particulates of adequate particle size are mixed with a polymer that exhibits low viscosities at temperatures typically provided by hot-melt glue guns to form rods that vary significantly in density from the base polymer. Novel articles can be manufactured by dispensing the composite from a glue gun into molds or by placement of the melt molding compound into preformed cavities within an end article.

Claims

1. A rod-shaped article, adapted to be used in a hand actuated hot-melt adhesive applicator or dispenser, comprising a thermoplastic magnetic composite, wherein the magnetic composite comprising:

(a) a thermoplastic polymer phase comprising 0.6 to 92 wt. % and 14 to 60 vol. % of the composite, the polymer characterized by melt flow properties such that the viscosity of the polymer at about 265°

C. is about 500-2000 cP; and

(b) a magnetic particulate comprising 3 to 99.4 wt. % and 31 to 86 vol. % of the composite, the particulate intermixed with the polymer phase, the particulate having about 0.005 to 3 wt. % of a coating of an interfacial modifier wherein the interfacial modifier at least partially coats the particulate, the particulate having a particle size where no more than 10 wt. % of the particles are under 10 microns;

wherein the particulate and polymer phase comprise greater than 95 vol. % of the composite, the composite having a density of 0.2 to 16 g/cm³ and a viscosity of less than about 100,000 cP at about the melt temperature of the composite.

2. The article of claim 1 wherein the composite comprise a nylon, a polyester or a polyurethane, and the polymer has a softening temperature above room temperature and the composite has a viscosity of lower than 25,000 cP about the melt temperature of the composite.

3. The article of claim 1 wherein the polymer has a softening temperature above room temperature and the composite has a viscosity of lower than 10,000 cP at about the melt temperature of the composite.

4. The article of claim 1 wherein the rod has a circular cross-sectional dimension of greater than 5 mm.

5. The article of claim 1 wherein composite is substantially metal deactivator free.

6. The article of claim 1 wherein the composite has a viscosity of 25,000 to 500 cP at a temperature of 100 to 240°

C.

7. The article of claim 1 wherein the polymer has a softening point of 40 to 185°

C.

8. A process of manufacturing a shaped magnetic article, the process comprising:

(i) using a hand actuated hot melt applicator, heating a portion of a rod to form a heated portion, the rod comprising a thermoplastic magnetic composite, the composite comprising;

(a) a thermoplastic polymer phase comprising 0.6 to 92 wt. % and 14 to 60 vol. % of the composite, the polymer characterized by melt flow properties such that the viscosity of the polymer at about 265°

C. is about 500-2000 cP; and

(b) a magnetic particulate comprising 3 to 99.4 wt. % and 31 to 86 vol. % of the composite, the particulate intermixed with the polymer phase, the particulate having about 0.005 to 3 wt. % of a coating of an interfacial modifier wherein the interfacial modifier at least partially coats the particulate, the particulate having a particle size where no more than 10 wt. % of the particles are under 10 microns;

wherein the particulate and polymer phase comprise greater than 95 vol. % of the composite, the composite having a density of 0.2 to 16 g-cm³ and the composite having a viscosity of lower than 100,000 cP at about the melt temperature of the composite;

(ii) forming the article by dispensing the heated portion through a nozzle of the applicator into an article shaped mold; and

(iii) magnetizing the article.

9. The process of claim 8 comprising dispensing the heated portion from the nozzle in the form of a melt into a mold, and cooling the composite in the mold.

10. The article of claim 8 wherein the composite comprise a nylon, a polyester or a polyurethane, and the polymer has a softening temperature above room temperature and the composite has a viscosity of lower than 25,000 cP at about the melt temperature of the composite.

11. The article of claim 8 wherein the polymer has a softening temperature above room temperature and the composite has a viscosity of lower than 10,000 cP at about the melt temperature of the composite.

12. The article of claim 8 wherein the rod has a circular cross-sectional dimension of greater than 5 mm.