Relating to foam filled honeycomb structures

Patent metadata

Field	Value
Publication number	US-10279514-B2
Application number	US-201415030618-A
Country	US
Kind code	B2
Filing date	Oct 20, 2014
Priority date	Oct 21, 2013
Publication date	May 7, 2019
Grant date	May 7, 2019

Abstract

Spherical heat foamable pellets ( 2 ) are used for reinforcing honeycomb structures ( 4 ). The pellets are preferably of average diameter from 0.5 mm to 0.9 mm and preferably at least 80% of the pellets have a diameter in this range. The pellets can form a free flowing stream which can be poured into the cells ( 5 ) of the honeycomb where they can be foamed by heating to form a reinforcing foam which can also bond the honeycomb structure to facing sheets. It is preferred that the pellets are based on a thermosetting resin and contain a curing agent that can cure the foamed resin to produce an integral rigid reinforcing foam within the cells of the honeycomb.

First claim

The invention claimed is:

1. Substantially spherical pellets for strengthening a sandwich panel comprising a honeycomb core wherein the pellets:
i) comprise a polymer and a thermally activated blowing agent;
ii) have an average diameter in the range of 0.5 mm to 0.9 mm;
iii) include a thermally activated curing agent;
wherein the substantially spherical pellets are dry, free flowing, and readily pourable and the substantially spherical pellets upon foaming in the honeycomb structure, results in a foam with substantially uniform mechanical properties throughout the foam.

2. The pellets according to claim 1 in which the polymer is an epoxy resin.

3. The pellets according to claim 1 in which at least 80% of the pellets have a diameter in the range of 0.5 mm to 0.9 mm.

4. A honeycomb structure in which at least one or more cells are filled by a foam obtained by providing the substantially spherical pellets of claim 1 that have been heated to cause the pellets to foam.

5. The honeycomb structure according to claim 4 in which the polymer is a thermosetting resin.

6. The honeycomb structure according to claim 5 wherein the thermosetting resin is an epoxy resin.

7. The honeycomb structure according to claim 4 in which at least 80% of the pellets have a diameter in the range 0.5 mm to 0.9 mm.

8. The honeycomb structure according to claim 4 provided with a facing sheet on at least one surface.

9. The honeycomb structure according to claim 8 wherein the facing sheets on the at least one surface comprise a prepreg of fibres in a curable matrix.

10. The honeycomb structure according to claim 9 in which the curable matrix is cured at the temperature used to foam the pellets.

11. The honeycomb structure according to claim 9 in which the curable matrix is an epoxy resin.

12. Substantially spherical pellets of average diameter in the range of 0.5 mm to 0.9 mm wherein the pellets comprise a thermosetting epoxy resin, a thermally activated blowing agent and a thermally activated curing agent for the thermosetting epoxy resin; and
wherein the substantially spherical pellets are readily dispensed as a dry free flowing state and are substantially free of agglomeration in the dry free flowing state.

13. Substantially spherical pellets according to claim 12 wherein at least 80% of the pellets have a diameter in the range of 0.5 mm to 0.9 mm.

Assignees

• Zephyros Inc

Inventors

• Meyer Francis
• Chene Morgan

Classifications

• B32B2250/40

  Symmetrical or sandwich layers, e.g. ABA, ABCBA, ABCCBA · CPC title

• B32B27/20

  using fillers, pigments, thixotroping agents · CPC title

• B32B2307/3065

  Flame resistant or retardant, fire resistant or retardant · CPC title

• C08J2363/00

  Characterised by the use of epoxy resins; Derivatives of epoxy resins · CPC title

• B32B27/08

  of synthetic resin · CPC title