Illustrator creats edges that are not there if I export an object

[#1]

Hi,

I work on a book cover with a background that is made of triangles. If I work in Illustrator the triangles aline perfectly and even if I zoom in as far as I can there is no space between two triangles visible. However if I export it no matter if jpeg, png or pdf, the exportet file happens to have white spaces between some triangles (as seen in the image attached). 

Does anyone know why that happens and how I can solve the problem? 

Thanks in advance, Malte 

[#2]

These are antialiasing artefacts.

You could try and put a brown object in the background to reduce the effect of the antialiasing.

[#3]

When exporting as an image, you could try to set the Anti-aliasing option to Art Optimized (instead of Type Optimized).