Then {HEAD ~ the inventors} developed {TAIL ~ a thermosensitive recording medium} using a diphenyl sulfone derivative by leaving one of the hydroxyl groups and replacing the other hydroxyl group with an alkoxy group in the diphenyl sulfone derivative  
Then { HEAD ~ the inventors } developed { TAIL ~ a thermosensitive recording medium } using a diphenyl sulfone derivative by leaving one of the hydroxyl groups and replacing the other hydroxyl group with an alkoxy group in the diphenyl sulfone derivative
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