Lines when I export an object with pattern

[Tetiana30217077ujuf]

Hello, I created an object in which I used a pattern as a fill, everything looks fine in Illustrator, but when I try to export it as png, these annoying lines appear, below I will attach 2 screenshots, please tell me how to fix this. 

Thanks in advance

[Ton Frederiks · Accepted solution]

Did you check Art Optimized for anti-aliasing method when exporting?