Japanese appliance in the US?

Can i use Japanese 100V iron (phillips 1200watt) and air purifier (daikin 580Watt) in the US (110V) without converter? Thank you.

It all may depend on those 10-20 volts. If the item you have cannot withstand that extra voltage, then it's going to overwork and stop working quicker than when it's 100V. It just depends on the manufacturer.

Most devices are built to have a 10% tolerance either way but as your voltage at home also varies during the day, this might bring it outside the acceptable range.
Personally I would use an extension block with surge protection and never leave these devices unattended and give it a go but there is no guarantee, especially with the iron.

Can i use Japanese 100V iron (phillips 1200watt)

FYI, the US uses 120v. Without voltage conversion your iron will run hotter than normal and could pose a fire hazard. Its life will also be reduced and it will likely burn out quicker than normal. Even running it on a converter is not very practical as 1200 watt converters are big and expensive. If you do decide to use it then you might want to keep it set lower than the maximum power (maybe around 80% max) and always keep an eye on it (good advice for irons in general).

and air purifier (daikin 580Watt) in the US (110V) without converter? Thank you.

Like this?

http://www.amazon.co.jp/%E3%83%80%E3%82%A4%E3%82%AD%E3%83%B3-DAIKIN-%E...

If so then I would run that on a converter if possible as it looks to have electronics that may be affected. In this case, a properly rated converter is not that expensive compared to the device.