Charging an object by friction does not violate charge conservation because the charge is:

1. Conservation constrains what rubbing two objects can do. 2. Rubbing can leave one object positively charged. 3. This universally obeyed law of nature is called the law of conservation of charge. 4. Neutral objects contain equal quantities of positive and negative charge. 5. So the charge is transferred between the objects rather than created. _Source: OpenStax College Physics for AP Courses 2e (CC BY 4.0), Ch 18 'Electric Charge and Electric Field', sections 18.1-18.8_