Blender OBJ to Minecraft block black texture 1.12.2

Hi. It's my first time when I'm using Blender to make custom block model to my mod. I've made test block with some additional random details on mesh to make sure model is loading ingame. After launching Minecraft the model is loading great, but it's texture doesn't works. Block has it's model, but it's completely black or white. In Blender I've maded Start UV, then painted on that block, then I've saved image texture as PNG and exported OBJ. Then to be sure if it's loading well, I've imported this model to another instance of Blender and it looks okay, but in Minecraft it's still black only. I already checked this model with texture on 3dviewer.net, and same result... model loaded, but no texture loaded, only black color. Can someone help me please? :(. I know it's better to use json or java, but I need to make more detailed model :( so I need to make OBJ