I found the answer

There already is a product.product multicompany rule (but it is inactive by default): "Product multi-company"
xml id: product.product_comp_rule
You can active it by going to settings => general settings. Check "manage multi company", then uncheck "share product to all companies"

from 

http://stackoverflow.com/questions/37500668/limit-products-to-company-assigned-to-user-in-multi-company-odoo-9