The Man in the White Suit
(1951)

Sidney Stratton (Sir Alec Guinness) is a research chemist.  He invents a fabric that is impossible to stain, cut or tear. It is indestructible.  He goes to the textile industry, thinking they will love his fabric.  They realize that an indestructible fabric means the end of their industry.  They try bribing Stratton to keep it a secret, but he refuses.  He is kidnapped and locked in an upper room of the mansion of one of the factory owners.  The owner's daughter helps him escape out the window hanging from a thread of his indestructible cloth.  He is dressed in a white suit of the super fabric.  Everyone takes off after him.  After a lengthy chase, he is captured in London at daybreak.  With the press, police and a huge crowd around, he is set to reveal his fabric.  However, the fabric begins to disintegrate, and Stratton is left in his underclothes.  The fabric was indestructible in the lab, but is not stable in ultraviolet light and disintegrates in the sunlight.  Stratton goes home alone.

Thanks Joseph!