can we sue a company if we took workman comp

Probably not.  In general, an employer who is a subscriber to the Texas Workers Compensation Insurance program is automatically responsible for any on the job injury without the necessity of a lawsuit.  The trade-off for the automatic liability is that, in general, an employee cannot sue his employer for an on-the-job injury.  There are some very limited exceptions to this rule in the case of an intentional act by the employer which causes the injury or an act caused by the employer's gross negligence.