If a child has attachment issues does this lead to any mental disorders as an adult?

Depends. Severe forms of attachment disorders in children can lead to personality problems in adults. However, such outcomes are not inevitable. Children can be amazingly resilient and "fix themselves" or benefit from therapy or simply find the right environment and people to help them deal with attachment problems as they get older.
No. Overall, everything is pervaded by the theory of "good enough" parenting. The research shows that kids, at best, remember "themes." that is, "dad was a nice guy, " or, "dad yelled a lot, " and not much more. Do your best, and realize that kids are individuals who will make their own mistakes and...Successes!