shield startup from employment IP agreement

That's a tough one on several levels - first, I would check your current contract to see if there is anything in there that differentiates whether you create the IP on company time or on personal time - sometimes contracts are drafted that way whereby if you create something on your own personal time, the IP is yours, not the company because you did not create it while actually working for the company. If your contract is silent as to that issue, then you may have some difficulties - your current company can claim that your IP creations are company IP, or if you effectively ask to "rewrite" your contract so as to spell out the separation of company time and personal/private time, your company will obviously know what you are up to and could lead to unpleasant circumstances for you on your current job or you could be asked to leave. I would consult a good contract attorney.

The answer is in the Singapore law and depends on the contract that you will conlude with your former employer.

When you were an employee, inventions you made as part of your contract, in the course of your duties with your former employer, became her property as carried out as part of an inventive mission, in light of your former duties and responsibilities within the firm. It was certainly "mission inventions" (as we say according to French law) and it is the Singapore Patents Act (Chapter 221, Part IX, "Employees'inventions") which has to apply.

Now you lead a start-up while being employed elsewhere, the legal system of employee inventions to which you were belonging is obviously no longer applicable from the point of view of your activities in your start-up, regarding (i) your new job with your current employer and (ii) the fact that your start-up is not competing with him, so the inventions and also creations (designs, software, other works…) made by you in your start-up will remain your property or the property of your start-up legally speaking unless you/your startup transfer expressly them and the corresponding IP rights – right to patent, copyright… – by means of an IP clause in the order contract between you and your current employer.

These are universal principles, but consulting an IP Nexus colleague of Singapore seems to me opportune anyway, at least to confirm the foregoing…

Your sincerely,
Simon

Since I travel between SG & KL, the short answer is it depends on the precise wording of the contract. In general courts consider anything done for the purpose of employment, eg hired to invent, using firm equipment or on company times, even use of customer lists (a potential commercial secret) to be owned by them. You can either get a waiver (eg volunteer open-source coding), buy them out (ie pay fair market price but have IP owned by you) or negotiate a compromise where in return for a slice of equity, you can tap into existing background IP (see group Spinout Meister). What courts tend to frown upon are onerous non-compete clauses, trying to limiting working knowledge (as compared with firm specific data) and anti-competitive behaviour. So it comes down to whether you see the existing employer as help or hindrance in the near future ... note the very fact that you are doing 2 jobs might make some companies nervous if they feel you are not giving 100% at work, especially if you are hinting you want to jump ship and taking colleagues with you.