There are two main reasons for the stickiness of rubber products: 1. Analysis of small molecule groups such as plasticizers. 2. Surface oxidation or degradation due to light.
Tackiness is due to the oxidation reaction of rubber in the presence of oxygen. As a result, polar groups such as hydroxyl and carboxyl groups increase. These polar groups are the reason why things are sticky. Namely, it is equivalent to becoming a sticker.