Your situation should be considered a service invention, and the company can sue you.
Article 6 of my country's "Patent Law" stipulates: "Inventions and creations completed in the performance of the tasks of the unit or mainly by utilizing the material and technical conditions of the unit are service inventions and creations. The right to apply for a patent for service inventions and creations Belongs to the unit; after the application is approved, the unit is the patentee.
The term "service inventions and creations completed by performing the tasks of the unit" as mentioned in Article 6 of the Patent Law refers to:
(1) Inventions and creations made in the course of one's own work;
(2) Inventions and creations made in the performance of tasks other than one's own work assigned by the unit;
(3) Inventions made within one year after resigning, retiring or transferring work, and related to the original work undertaken by the original unit or the tasks assigned by the unit.
As mentioned in Article 6 of the "Patent Law". The unit includes temporary work units; the “material and technical conditions of the unit” as mentioned in Article 6 of the Patent Law refer to the unit’s funds, equipment, parts, raw materials or technical data that are not disclosed to the public.