Polycarbonate. Is it all the same?

[LENNY]

Polycarbonate. Is it all the same?
I dont think so. You can hear it cuts differently depending on the manufacturer!
How can we tell the difference? Is it published?
VE, Younger, Sola, Essilor, China....

[d_a_h_u_k]

I'm not familiar with polycarbonate manufacturing, but with other materials you can get different properties by using different types of additives or by changing the curing cycles. Each factory will have a slightly different recipe for the same material.

I imagine polycarbonate is the same.

[edKENdance]

Polycarbonate. Is it all the same?
I dont think so. You can hear it cuts differently depending on the manufacturer!
How can we tell the difference? Is it published?
VE, Younger, Sola, Essilor, China....

I've also wondered about this. What makes Airwear different enough from poly for it to warrant it's own name?

[MasterCrafter]

http://www.resolutionlenses.com/whynew.html

[Ghost Machine]

I've also wondered about this. What makes Airwear different enough from poly for it to warrant it's own name?

If it looks like a duck, walks like a duck and quacks like a duck AND your name is Essilor....it's not necessarily a duck, but whatever your marketing dept decides is a cool name for it instead. Rebranding. Likewise, you can call it anything you like in your practice/business.

[Chris Ryser]

If it looks like a duck, walks like a duck and quacks like a duck AND your name is Essilor....it's not necessarily a duck, but whatever your marketing dept decides is a cool name for it instead. Rebranding. Likewise, you can call it anything you like in your practice/business.

Polycarbonates, commonly known by the trademarked name Lexan, are a particular group of thermoplastic polymers. They are easily worked, moulded, and thermoformed. Because of these properties, polycarbonates find many applications. Polycarbonates do not have a unique plastic identification code and are identified as Other, 7.

Polycarbonate derived from BPA is a very durable material. Although it has high impact-resistance, it has low scratch-resistance and so a hard coating is applied to polycarbonate eyewear lenses and polycarbonate exterior automotive components. The characteristics of polycarbonate are quite like those of polymethyl methacrylate (PMMA, acrylic), but polycarbonate is stronger, usable in a wider temperature range but more expensive. This polymer is highly transparent to visible light and has better light transmission characteristics than many kinds of glass.

Polycarbonate has a glass transition temperature of about 150 °C (302 °F), so it softens gradually above this point and flows above about 300 °C (572 °F). Injection moulding is more difficult than other common thermoplastics owing to its non-Newtonian fluid flow behaviour. Tools must be held at high temperatures, generally above 80 °C (176 °F) to make strain- and stress-free products. Low molecular mass grades are easier to mould than higher grades, but their strength is lower as a result. The toughest grades have the highest molecular mass, but are much more difficult to process.

[Geirskogul]

How does copy-and-pasting from Wikipedia help with that specific question? There are many polycarbonates, and I think it would be nice to know if there are multiple types in use for optical lenses, or if it's just one main formulation that's sold under different names.

Hell, I don't even know if, becides aspheric optics in one and not the other, if the two types we sell are any different in makeup or durability.

[OIC]

I think Chris was giving you the answer to the question you asked. Polycarbonate is what it is, as there are few who actually make the pellets used in the molding process. What differentiates it from one manufacturer to the next is more in the realm of the quality of the manufacturing process, the equipment used and the environment, the people working in the plant, the quality of the molds, the quality and design of the optics used to manufacture the molds, and the hard coating, which must be applied to all polycarbonate lenses due to the soft surface of polycarbonate. Airwear is simply a brand name, like Varilux, but it distinguishes itself from their other product (Gentex) by being aspheric vs. spherical, and having a more scratch resistant hard coating. Vision-Ease does similar with its Continua and Tegra branded lines.
Where you might see a difference in durability is more relative to the hard coating than to the poly itself. Since the poly material doesn't tint, softer hard coatings are used so that they can absorb dye. Harder coatings are recommended since they are more scratch resistant, but they also don't tint well, or not at all.

[scriptfiller]

The only way I can see poly differing between manufacturers is the curing/HC process. I have noticed the smell while being cut/drilled differs manufacturer to manufacturer.

[LENNY]

The only way I can see poly differing between manufacturers is the curing/HC process. I have noticed the smell while being cut/drilled differs manufacturer to manufacturer.

The noise also!
It just sounds different! It must be different.

[Chris Ryser]

The only way I can see poly differing between manufacturers is the curing/HC process. I have noticed the smell while being cut/drilled differs manufacturer to manufacturer.

There is no so called curing process to Polycarbonate. The basic material come in pellets from the manufacturer to the molding company.

The molder heats the material which then is transported by hoppers into the injection machine which presses the liquid material into the molds, which then are cooled off and opened to release the finish product. Usually the lenses are made in molds containing 4 to 6 lenses at a time.

[Yeap]

1 more question about polycarbonate material.. is the quality purely base on the Abbe value? or there is other way to determine their quality? we only have that as a reference from the manufacturer..

[Chris Ryser]

1 more question about polycarbonate material.. is the quality purely base on the Abbe value? or there is other way to determine their quality? we only have that as a reference from the manufacturer..

Polycarbonate has only one value overall on whatever you want to know as it is the only material of its kind.
The closest category of plastics used in optical lenses is PMMA.

From my website at : http://optochemicals.com/polycarbonate_properties.htm

Polycarbonate Physical Properties

Specific Gravity
Units g/cm3

1.2

Continuous Operating Temperature
Unit °C - 5,000Hrs / 20,000Hrs

125/115

Tensile Strength
Units MPa

65

Impact Resistance
Units Charpy KJ/m2

20

Impact Resistance
Units Izod KJ/m2

9

Hardness
Units Rockwell M

75

Co-efficient of Thermal Expansion
Units mm/(mmxK) x 10-6
avg value 23-60°C

65

Dielectric Strength
Units KV/mm

28

Surface Resistivity
Units Ohms

1x1018

Flammability
Oxygen Index %

26

Flammability
UL94

V2

Light Transmittance
Units ASTN D 1003 (%)

[PRECISIONLAB]

As with any material there will be different grades available. With poly I'm sure there are "grades" ment for various applications. I doubt the poly used for CD/DVD's, car headlights etc is the same used for optical lens products. With that in mind, lens manufacturers may use various grades of poly for thier products. Essilor poly products (Airwear and Gentex) have a much more crytsal clear appearance than do Sola , Vision Ease or other manufacturers. If you have both in stock varify for yourself..you will definetly notice the difference..airwear clear..other poly appears "milky". Optically Airwear finished lenses powers appear crisp in the lensometer. I'm sure the manufacturing process is a factor as well..according to my VE rep Continua is a UV cured process versus Tegra which affects SRC quality and tintability. I use lenses from all the major poly lens suppliers and believe poly "is what it is"

[Chris Ryser]

As with any material there will be different grades available. With poly I'm sure there are "grades" ment for various applications. I doubt the poly used for CD/DVD's, car headlights etc is the same used for optical lens products. With that in mind, lens manufacturers may use various grades of poly for thier products.

Margard seems to be the optical quality as far as I can see.

http://kbam.geampod.com/KBAM/Reflection/Assets/Thumbnail/11608_10 (PDF File)
Made from high optical quality Lexan resin, Lexan Margard* MR5E sheet is UV- and mar-resistant, and virtually unbreakable.
kbam.geampod.com/KBAM/Reflection/Assets/Thumbnail/11608... kbam.geampod.com/KBAM/Reflection/Assets/Thumbnail/11608_10.pdf

SABIC Innovative Plastics is a trademark of Sabic Holding Europe BV
* Exell, Lexan and Margard are trademarks of SABIC Innovative Plastics IP BV
© Copyright 2008 SABIC Innovative Plastics IP BV. All rights reserved.

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[Geirskogul]

So we're getting two different answers. Chris says that all optical poly is the same, and Precisionlab says that theyr'e different. Which is is?

[LENNY]

Interesting!

[Yeap]

Chris thank you for the answer.

so is that Airwear from Essilor, Polylite from Carl Zeiss, Trilogy from younger optic is not actually a polycarbonate material?

[Jacqui]

Trilogy is actually Trivex (good stuff). The others are some other garbage.

[Chris Ryser]

............................so is that Airwear from Essilor, Polylite from Carl Zeiss, Trilogy from younger optic is not actually a polycarbonate material?

Trilogy is not Poly as Jaqui says...............it is Trivex that comes from PPG and is a much newer invention than Poly.

The first Poly lens manufacturer was in Italy in the late 1060s early 70s, but never become successful.

By the way I heard somer rumors that there are a couple of Lens Factories in China that are making Poly lenses for all the big names. Just different packaging.

[MasterCrafter]

According to Optima it's in the way they process the materials into lenses.

Optima is claiming this :

Optima holds exclusive patents to its unique manufacturing process, which uses ECM-9™ (Extrusion Compression Manufacturing) to produce its birefringence-free polycarbonate lenses, the only such lenses on the market.


They claim this creates less stress on lenses compared to standard injection molding.


I can defiantly see a difference in the way the lens looks on my blocker.


IMO there is no difference in the material itself, but whether its injection molded or "poured" as Optima is claiming.

[Audiyoda]

According to Optima it's in the way they process the materials into lenses.

Optima is claiming this :

Optima holds exclusive patents to its unique manufacturing process, which uses ECM-9™ (Extrusion Compression Manufacturing) to produce its birefringence-free polycarbonate lenses, the only such lenses on the market.


They claim this creates less stress on lenses compared to standard injection molding.


I can defiantly see a difference in the way the lens looks on my blocker.


IMO there is no difference in the material itself, but whether its injection molded or "poured" as Optima is claiming.

Here's the answer everyone is looking for. Some companies like Optima and Resolution use unique processes that allow them to offer certain features that make poly appear 'different'. Then there are differences in naming - Essilor for example offers Airwear and Gentex - they are the same except Airwear comes with a return warranty (and the plus lenses are aspheric I believe). Vision Ease offers their Continua line and the Tegra line - Tegra sounds radically different when edged - the Tegra FSV lenses are aspheric and have that rather incredible front coat whereas the Continua lenses are spherical with a standard coating.

But in the end, the substrate is still polycarbonate.

[Chris Ryser]

I can defiantly see a difference in the way the lens looks on my blocker.


IMO there is no difference in the material itself, but whether its injection molded or "poured" as Optima is claiming.

Yoiu better look again on your blocker. Lexan or the generic Poly comes in pelletes as raw material it is heated to get soft and thgen has to undergo the pressure treatment of the injection equipment to be proceed into the molds. There is no such thing as pouring this material.

Liquid monomers can be poured and then cured in heat or other means. But this does not work with Poly.

[Audiyoda]

Yoiu better look again on your blocker. Lexan or the generic Poly comes in pelletes as raw material it is heated to get soft and thgen has to undergo the pressure treatment of the injection equipment to be proceed into the molds. There is no such thing as pouring this material.

Liquid monomers can be poured and then cured in heat or other means. But this does not work with Poly.

While I do agree that Optima's claim that their poly is poured is bogus, their lenses do appear to have less "stress" than some other poly lenses when viewed through a blocker. I can see differences between the Continua and Tegra lenses from Vision Ease. IMO some companies just use a better manufacturing process than others.

[Chris Ryser]

While I do agree that Optima's claim that their poly is poured is bogus, their lenses do appear to have less "stress" than some other poly lenses when viewed through a blocker. I can see differences between the Continua and Tegra lenses from Vision Ease. IMO some companies just use a better manufacturing process than others.

I have been on the Optima site, and I found that Optima lenses are not made with Polycarbonate at all. They are made from polyutherane high index material as per their own statement. :

at http://www.optima-hyper.com/frmadvan.htm



The thinnest single vision lens made or available anywhere. These polyurethane high index plastic lenses are up to 50% thinner and 50% lighter than ordinary plastic lenses and are five times more impact resistant.

So if they look different to you, that is why,.................... they are not the same baby we are talking about. and we have to disregard your opinion regarding this discussion.

Check it all out on their home page at:
http://www.optima-hyper.com/frmadvan.htm