Modified polyimide resin and preparation method thereof

The invention provides a preparation method of modified polyimide resin. According to the preparation method, a liquid crystal polymer with low water absorption is added into a polyamide acid (PAA) solution; and a catalyst and a dehydrating agent are added into the mixture, and heating is performed to separate out a resin mixture. According to the method, an auxiliary agent with low water absorption is screened and added into the polyamide acid solution which is not separated out, so that the auxiliary agent and polyimide resin can form modified resin in which the auxiliary agent and the polyimide resin are mutually wrapped and uniformly mixed, and lower water absorption can be achieved by using a small amount of auxiliary agent. 本发明提供一种改性聚酰亚胺树脂的制备方法，即在聚酰胺酸(PAA)溶液中加入低吸水率的液晶聚合物。在混合物中加入催化剂、脱水剂，加热析出树脂混合物。这种方法通过筛选低吸水率的助剂，加入未析出的聚酰胺酸溶液中，可以与聚酰亚胺树脂形成相互包裹、混合均匀的改性树脂，使用较少量的助剂即可达到较低的吸水率。