Production of joints

Abstract

Surfaces 1, 2 are bonded together by a heat activated adhesive 3 that is applied to a surface 2 to cover an area greater than the area that is to form the bond, the two surfaces 1, 2 are brought together and the adhesive 3 activated so that it creates the bond and also covers the exposed edges of the surfaces to provide an aesthetically pleasing and coatable corrosion and rust protective layer.

Claims

1. A method for joining two panels comprising: adhering a heat activatable and expandable sealant material in a plurality of locations to a first panel, a second panel, or both, wherein the expandable sealant material in each of the plurality of locations is located at least partially within, and also extending beyond, an area where the bond between the second panel and the first panel is to be formed, and the first panel is located adjacent to the second panel; assembling the first and the second panel to form a joint; and activating the heat activatable and expandable sealant material to bond the panels together and provide a protective layer outside the region of the bond that covers one or more exposed edges of the first panel, the second panel, or both.

2. The method of claim 1, wherein the expandable sealant is applied to one of the panels to be joined.

3. The method of claim 1, wherein the expandable sealant is applied to both panels to be joined.

4. A method according to claim 1, wherein the joint is a hem flange.

5. A method according to claim 1, wherein the first and second panels are parallel panels and the expandable sealant material extends beyond on side of an overlapping area.

6. A method according to claim 1, wherein the first and second panels are parallel panels and the expandable sealant material extends beyond one side of an overlapping area.

7. A method according to claim 1, wherein upon activation the expandable sealant material expands by from 25% to 100% of an original unexpanded volume.

8. A method according to claim 1, wherein the expandable sealant material extends beyond an area where the joint is formed by up to 10 mm.

9. A method according to claim 1, wherein the expandable sealant material includes an impact modifier, a blowing agent, a curing agent, a filler, or a combination thereof.

10. A method according to claim 1, wherein the expandable sealant material includes at least three of the following: a) 2 to 80% by weight epoxy resin; b) 2 to 70% by weight polymer (e.g. epoxy)/elastomer adduct; c) one or more additional polymers, which typically include a one or more ethylene polymers or copolymers; d) 2 to 70% by weight impact modifier; e) up to 5% by weight of a blowing agent; f) up to 7% by weight of a curing agent; and g) a filler.

11. A method according to claim 1, wherein the expandable sealant material expands at a temperature within the range 120 C. to 260 C.

12. The method according to claim 1, wherein the method is free of an additional surface finish or wax protection applied during activation of the expandable sealant material, after activation of the expandable sealant material, or both.

13. The method according to claim 1, wherein the expandable sealant material is applied via an extrusion process.

14. The method according to claim 10, wherein the expandable sealant material is free of an adduct.

15. The method according to claim 1, wherein the joint is free of a flange.

16. The method according to claim 10, wherein the impact modifier includes at least 97% by weight of one or more shell/core impact modifiers.

17. The method according to claim 10, wherein the filler is 30% to 55% by weight of the expandable sealant material.

18. The method according to claim 1, wherein the expandable sealant material is adhered in two locations, each of the two locations at least partially within, and also extending beyond, an area where the bond between the second panel and the first panel is to be formed.

19. The method according to claim 18, wherein after activation, the expandable sealant material in each of the two locations expands to fill a void between the two locations.

Description

(1) The present invention is illustrated but in no way limited by reference to the accompanying drawings in which

(2) FIG. 1 shows a prior art with seal employing an adhesive and the wax.

(3) FIG. 2 shows a hem flange following EP 2231348 prior to cure of the adhesive;

(4) FIG. 3 shows a hem flange following EP 2231348 after expansion of the adhesive;

(5) FIG. 4a shows a hem flange following EP 2231348 showing the unattractive surface unsuitable for coating;

(6) FIG. 4b is an expanded version of a section of FIG. 4a;

(7) FIG. 5a shows a hem flange following EP 2231348 showing how the foam can extend beyond the desired location;

(8) FIG. 5b is an expanded version of a section of FIG. 5a;

(9) FIG. 6 shows a hem flange according to the present invention;

(10) FIG. 7a shows a flat assembly according to the present invention with the adhesive on one panel;

(11) FIG. 7b shows the flat assembly of FIG. 7a with the adhesive on one panel the adhesive being in an expanded state;

(12) FIG. 8a shows the flat assembly according to the present invention with the adhesive on both panels;

(13) FIG. 8b shows the flat assembly of FIG. 8a with the adhesive on both panels in an expanded state.

(14) FIG. 1 shows a hem flange sealing between a first panel (1) whose end is bent to form a U shape into which the end of a second panel (2) extends where it is held by the foamed adhesive (3) which extends within the U shape. The joint is provided with a protective PVC layer (4) and a wax layer (5) in order to provide corrosion protection and a coatable surface.

(15) FIG. 2 shows a similar hem flange in which the adhesive (3) is provided in unfoamed state on the surface of panel (2) and FIG. 3 shows how the adhesive may be foamed to secure the two panels together and exude out of the U shape to form the protective regions (6) and (7). FIGS. 4a and 4b show how with the system of FIGS. 2 and 3 the high expansion ratio of the adhesive provides an irregular foam which is unsightly and difficult to coat and also results in a foam the extent of which is difficult to control.

(16) FIG. 5a shows how the large expansion ratio required for the techniques of EP 2231348 can result in the foam extending further than required as shown in more detail in FIG. 5b. The foam is not only unsightly but can be knocked and damaged and/or removed.

(17) FIG. 6 shows a system according to the present invention for forming a hem flange in which the adhesive (8) is in an unfoamed state and protrudes beyond the area of overlap at (9) and (10) ready for activation to form the bond.

(18) FIG. 7a shows how the invention may be used to bond together two overlapping flat panels (11) and (12) with the adhesive (13) extending at one end (14) beyond the area of overlap. FIG. 7b shows how the adhesive may be foamed to bond the panels together and provide the protective coatable strip (15).

(19) FIG. 8a shows how two pieces of the adhesive (16) and (17) may be used according to the invention to extend beyond both ends of the overlapping area and which may be foamed as shown in FIG. 8b to bond the panels together and provide the protective layers (18) and (19).