markr13
Member
Registered: Sep 2000
Location:
Posts: 7 |
The Facts Behind PVC (Vinyl) Polymer
quote: Originally posted by MelHerd
My concerns about DIY protectors would be any plastic additives in the plastic used for screen protection. These additives could migrated to the LCD plastic screen and change (read damage) the plastic. The most common ones that I would worry about would be plasticizers - used to make the plastic soft and pliable. I do not believe that vinyl has plasticizers (or any additives for that matter). Most clear plastics tend to not have additives as the additives may affect the clarity of the plastic. So if the plastic used as a screen protector is clear - chances are it's ok to put on your screen.
Adhesives may also have volatile materials in them that could affect the LCD plastic. Any thing that you spray on the vinyl to help it cling could also affect the plastic - water based products are the way to go as they would have little or no affect on the plastic. If anybody uses DIY screen protectors with sprays or adhesives - please post how well it worked and how long it has been on your screen. Effects on the LCD screen would take months or longer to be visible.
OK, there seems to be a bit of misconception about "vinyl" screen protectors and how they may affect your device, so here goes...
PVC is a very inexpensive plastic that is almost useless in its native version. To make it work as a plastic for commerce, it must contain numerous additives to function correctly. These range from thermal stabilizers (this polymer chars readily when molded without them), processing aids, impact modifiers, flow aids, plasticizers and others. There are two basic flavors of PVC, rigid and flexible. The rigid variety is used for structural applications such as PVC siding and need not concern this group. The type we encounter on auto dashboards, covers for furniture, books and, yes, screen protectors is the flexible type. The main reason it can be made flexible is by adding phthalate plasticizers which are high boiling, oil like materials. The plasticizers reduce polymer crystallinity and improve, not decrease, clarity. Interestingly enough, olefin polymers (polyethylene -- food wrap) could also be used, are flexible on their own, but they all have significant crystallinity and would cause unacceptable haze unless they are a special copolymer to prevent this.
Do plasticizers migrate? Yes, they do, in small quantities. This is a major concern in the case of hospital infusion bags which are made from flexible PVC and you may have seen this in recent news reports. Some phthalate plasticizers have been linked with cancer in animals so this concern is a valid one. Will it cause damage to your PDA screen? I have never seen nor heard of any such damage. WriteRights (made from PVC and adhesive) have been produced since 1994 and I have never heard anyone comment on screen damage. Nor have any of the other manufacturers of vinyl screen protectors (PilotRight, VSPS) have any problems reported from this. It seems a very unlikely event. Even if some migration occurred and caused softening of the plastic outer layer of the screen, periodic removal and cleaning would probably mitigate this.
|