Why do good floppy disks go bad?

Tom Gardner t.gardner at computer.org
Fri Apr 8 14:11:04 CDT 2016

Sorry, to a EE they are all epoxies, but:

"BINDER: A polymer such as polyester-polyurethane used to bind magnetic
particles together and adhere them to the base film in the manufacturing of
magnetic media."

"Polyester polyurethane is the workhorse of polyurethane films. It offers
excellent strength and long-term stability"

I think properly cured all binders used are pretty stable.


-----Original Message-----
From: Chuck Guzis [mailto:cclist at sydex.com] 
Sent: Thursday, April 07, 2016 10:47 PM
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: Why do good floppy disks go bad?

On 04/07/2016 10:06 PM, Tom Gardner wrote:

> And it's not likely the binder, fully cured epoxies are also very 
> stable. Note disks do not have the tension problem that tape has.

There, I have to respectfully disagree.  Floppy disks do not use an epoxy
binder, but usually a polyurethane-based one. (Most are proprietary
formulations).  Hard disk coatings usually use an epoxy-phenolic binder, but
they're not on a flexible substrate.

Polyurethane isn't forever and tends to be somewhat hygroscopic.


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