Composite foam

Patent metadata

Field	Value
Publication number	US-10933609-B2
Application number	US-201716089737-A
Country	US
Kind code	B2
Filing date	Mar 31, 2017
Priority date	Mar 31, 2016
Publication date	Mar 2, 2021
Grant date	Mar 2, 2021

Abstract

Composite materials having superior material properties useful as impact absorbing devices can be fabricated by embedding a lattice structure (e.g., polymer lattice structure) within a foam, so that the foam reinforces the lattice structure under impact. Materials and dimensions of the foam and the lattice structure may be selected to achieve composite materials having tailored impact absorbing elastic and/or viscoelastic responses over a wide range of temperatures.

First claim

The invention claimed is:

1. An elastic or viscoelastic composite material useable as an impact absorbing device, comprising:
a lattice structure embedded in a foam, wherein:
the lattice structure comprising interconnected struts each having a length and a width;
the foam comprising semi-closed cells, the semi-closed cells each comprising a substantially continuous cell wall defining a cell size, the cell size being smaller than the length of the strut, wherein the continuity of the is cell wall is interrupted by least one perforation or aperture each having a diameter, the diameter of the at least one perforation or aperture being smaller than the cell size;

wherein upon an impact, the foam reinforces the lattice structure.

2. The elastic or viscoelastic composite material of claim 1 , wherein:
the lattice struts comprise a first viscoelastic material, and
the foam comprises a second viscoelastic material,
such that an impact that generates an elastic response in the composite material generates a stress of no more than 5 MPa in the composite material.

3. The elastic or viscoelastic composite material of claim 1 , wherein the perforations or apertures of the foam have dimensions that reinforce the lattice structure struts against elastic buckling under dynamic compression, such that the lattice structure elastically dissipates energy of the impact while force from the impact is still building up in the composite material.

4. The elastic or viscoelastic composite material of claim 1 , wherein the lattice struts comprise a first viscoelastic material, and the foam comprises a second viscoelastic material such that a peak force of no more than 2.16 kN is generated in the composite material in response to a 5.5 kg weight having an energy of 15 Joules impacting a 45 mm by 45 mm area on the composite material.

5. The elastic or viscoelastic composite material of claim 1 , wherein the lattice struts comprise a first viscoelastic material, and spacing, and the foam comprises a second viscoelastic material such that a stress of 0.1 MPa to 5 MPa is generated in the composite material in response to a 5.5 kg weight having an energy of 15 Joules impacting a 45 mm by 45 mm area on the composite material.

6. The elastic or viscoelastic composite material of claim 1 , wherein the composite material is viscoelastic so that two or more equivalent and repeated impacts on the composite material generate maximum forces in the composite material that have a variability of less than 0.7 kN from each other.

7. The elastic or viscoelastic composite material of claim 1 , the struts comprise a polymer having a glass transition temperature and the foam is viscoelastic such that impacts on the composite material under temperatures ranging from −17° C. to 50° C. generate maximum forces in the composite material within 3 kN of each other.

8. The elastic or viscoelastic composite material of claim 1 , wherein the lattice structure is a polymer lattice structure.

9. The elastic or viscoelastic composite material of claim 8 , wherein the lattice structure comprises polyurea.

10. The elastic or viscoelastic composite material of claim 1 , wherein the foam comprises a blend between a polymeric di-isocyanate and a polyol or amine.

11. The elastic or viscoelastic composite material of claim 1 , wherein the foam comprises a polyurea foam comprising an oligomeric diamine polyol combined with diisocyanate.

12. The elastic or viscoelastic composite material of claim 11 , comprising a ratio of diamine polyol to diisocyanate ranging from 1:1 to 10:1.

13. The elastic or viscoelastic composite material of claim 12 , wherein the ratio is 4:1.

14. The elastic or viscoelastic composite material of claim 1 ,
wherein the foam has a density in the range of 30 kg/m 3 and 500 kg/m 3 ,
wherein the length is in a range from 1 micrometer to 100 centimeters and the width is in a range of 1 micrometer to 100 centimeters, and
wherein the cell size is in a range of 1 to 1000 micrometers.

15. The elastic or viscoelastic composite material of claim 11 , wherein the cell size is in a range from 1 micron to 1000 microns and the diameter of the at least one perforation or aperture is in a range from 1 micron to 1000 microns and the foam has a density in the range of 30 kg/m 3 and 200 kg/m 3 .

16. The elastic or viscoelastic composite material of claim 11 , wherein the foam comprises a viscoelastic material having a temperature stability characterized by a glass transition temperature controllable in a range from Tg (−50° C.) up to at least room temperature.

17. The elastic or viscoelastic composite material of claim 1 , wherein the foam has a density in a range between 50 kg/m 3 and 800 kg/m 3 .

18. The elastic or viscoelastic composite material of claim 14 , wherein the diameter of the at least one perforation or aperture is independently controlled from the cell size and is in a range of 1-1000 microns.

19. The elastic or viscoelastic composite material of claim 1 , wherein the foam comprises a viscoelastic material having a density in a range of 30 kg/m 3 and 200 kg/m 3 .

20. The elastic or viscoelastic composite material of claim 1 , wherein the composite material is viscoelastic below 5 degrees Celsius and above 45 degrees Celsius.

21. The elastic or viscoelastic composite material of claim 1 , wherein the composite material comprises a bilayer comprising a layer of foam infused into the lattice structure and a layer of foam not having the lattice structure.

22. A helmet, shin guard, vest, or armor comprising the elastic or viscoelastic composite material of claim 1 , wherein the composite material is exposed and would be in direct contact with an impact.

23. A method of making an elastic or viscoelastic composite material useable as an impact absorbing device, comprising:
forming a composite material comprising a lattice structure embedded in a foam, wherein:
the lattice structure comprising interconnected struts each having a length and a width;
the foam comprising semi-closed cells, the semi-closed cells each comprising a substantially continuous cell wall defining a cell size, the cell size being smaller than the length of the strut, wherein the continuity of the is cell wall is interrupted by least one perforation or aperture each having a diameter, the diameter of the at least one perforation or aperture being smaller than the cell size;

wherein upon an impact, the foam reinforces the lattice structure.

24. The method of claim 23 , further comprising:
preparing the lattice structure using a polymer; and
foaming a mixture through the lattice structure so as to form the foam such that the lattice structure embedded in the foam.

25. The method of claim 24 , wherein the mixture comprises a blend between a polymeric di-isocyanate and a polyol or an amine.

26. The method of claim 24 , wherein the lattice structure is placed in the mixture prior to the foaming.

27. The method of claim 24 , further comprising:
positioning the lattice structure in a mold; and
pouring the mixture into the mold, wherein the foaming results in the mixture rising up in the mold and infusing with the lattice structure.

28. The method of claim 24 , further comprising:
continuously feeding the lattice structure through a top roller;
continuously feeding the mixture on a surface carried by a bottom roller, the mixt

Assignees

• Univ California

Inventors

• Gupta Vijay
• Ramirez Brian Jouse
• Misra Utkarsh

Classifications

• B29C44/332 Primary

  the preformed parts being three-dimensional structures · CPC title

• B32B2437/00

  Clothing · CPC title

• A63B2071/1258

  for the shin, e.g. shin guards · CPC title

• B29K2105/041

  Microporous · CPC title

• B32B2266/06

  Open cell foam · CPC title