Bonding Polycarbonate Sheet

One question that we are often asked is how can two Polycarbonate sheets be bonded together?

At HighLine Polycarbonate we are mainly involved in producing Polycarbonate sheets with a wide range of high tech properties. We only engage in a limited amount of fabrication which includes routing of the sheets into finished part shapes.

We do not engage in fabrication that requires bonding of two sheets together. Some of our customers do engage in this type of fabrication and we will list some of the methods that we know about for joining two sheets of Polycarbonate together. We would be very interested to hear from our readers about other methods that they know about so that we can update the post with additional information.

We do not plan to cover physical methods of joining sheets together such as rivets, screws and tapes.

- The first method that we know about is using Methylene Chloride or a 60%/40% mixture of Methylene Chloride and Ethylene DiChloride. This solvent bonding technique is known to give a good bond strength and excellent optical clarity along with low capital investment. The mixture of Methylene Chloride and Ethylene DiChloride gives a slightly longer curing time than neat Methylene Chloride allowing more time to get the parts in the correct position; this is particularly important for larger parts. Suppliers of these chemicals can be found on Google. We recommend reading the Material Safety Data Sheet for information on safe handling and disposal before using any chemicals. We also recommend that you test any method on a small part before using on critical parts.

Before starting the solvent bonding process, both surfaces should be cleaned with warm water. If there are greasy areas, IsoPropanol (IPA) should be used to wipe the surfaces clean. Some fabricators recommend dissolving between 2% and 5% Polycarbonate saw dust in the Methylene Chloride or Methylene Chloride/Ethylene DiChloride solvents before use in order to give a stronger bond strength. We have yet to see any evidence that the saw dust improves the bond strength. In any case, if you choose to try this method, make sure that all of the saw dust is fully dissolved before use, because otherwise lumps of saw dust may prevent good surface contact between the two parts. Another recommendation that we have heard from fabricators is that in order to prevent whitening of the joint occurring, 10% Glacial Acetic Acid should be added to the solvents. Whitening does not always occur, so we would only recommend that you try this solution if you are having problems with whitening on your particular parts.

Having made up the solution, the solvent should be applied to one of the clean parts. The two parts should then be clamped together with several hundred psi pressure for about 5 minutes. The parts should then be allowed to cure in a well ventilated area at room temperature for between two and five days.

- The second method is to use an adhesive; this is a cheaper solution than solvent bonding but we believe that the bond strength and the optical clarity are not as good. Many customers have had excellent results with products such as "Weld-on". These products can easily be found using Google.

- Other methods such as vibration welding and ultrasonic welding have had varying degrees of success depending on the part shape and thickness. We would suggest that you contact manufacturers of the equipment to see if these options are suitable for your needs. These methods would require capital investment.

- The final option that we know about is to laminate the two parts together using an interlayer material such as transparent Polyurethane. This method is often used to manufacturer ballistics laminates where Polycarbonate layers are bonded to glass. This method requires a lot of specialist knowledge and equipment, such as an autoclave so it is unlikely to be viable for the majority of applications.

We look forward to hearing about more bonding methods from our readers.

FDA and NSF Standard 51 grades and UV absorbers

Polycarbonate sheet is widely understood to block UV wavelengths below 385-390 nm. What is not so well known is it is not the Polycarbonate that blocks these wavelengths, but rather the UV absorbers that are added to the Polycarbonate that block the UV light.

Polycarbonate sheet that has no UV absorbers will only block wavelengths below 290 nm. Unfortunately wavelengths below 385 nm will cause the Polycarbonate to weather and become brittle and yellow. Manufacturers therefore add UV absorbers to the Polycarbonate resin to give it some protection against the UV light. Some outdoor grades of Polycarbonate also have an additional cap layer or coating heavily loaded with additional UV absorbers to further protect the sheet against the affect of UV light.

There are some grades of Polycarbonate, that are often known as FDA or NSF Standard 51 compliant grades that have no UV absorbers. The reason that no UV absorbers are added is that these grades are designed to be used in the Food Processing environment and the UV absorbers are not approved by the FDA to be used in Food Processing areas. The manufacturers therefore produce grades without the UV absorbers. Because these FDA grades of Polycarbonate sheet have no UV absorbers, they should not be used outside as they will yellow very quickly.

One question that we are often asked is are the FDA approved grades safe to be used in food contact applications? The FDA grades of Polycarbonate sheet do not have UV absorbers in them because they are not approved for materials used in Food Processing environments. However, the Polycarbonate itself does still have Bisphenol A or BPA in it and there is currently a great deal of debate about whether BPA is safe in food contact applications such as baby feeding bottles. As a result of this debate, at HighLine Polycarbonate we do not sell any Polycarbonate sheet that will be used in applications where it comes into regular, direct contact with food. However, FDA grades of Polycarbonate sheet can be used as machine guards to protect operators on food packaging lines when the machine guards do not come into contact with food that will be eaten.

One un-intended market for FDA approved grades of Polycarbonate sheet is to customers who bond Polycarbonate sheet to other materials using a UV cured adhesive. The adhesive requires light from a UV lamp to pass through the sheet in order to bond it to another material. The UV absorbers in Standard Polycarbonate sheet block the UV light from the lamp preventing the adhesive from curing. By using an FDA grade of Polycarbonate sheet, the adhesive is able to be cured effectively. After bonding, the sheet can be protected against UV light by adding a coating with UV absorbers.

Kinetic Energy of Ballistics rounds and transparent armor

We are often asked about the difference between bullet resistant windows installed in 24hrs stores or banks and the transparent armor used by the military.

The bullet resistant windows in convenience stores and banks are often made of cell cast acrylic sheet or a combination of acrylic and Polycarbonate. They are often about 1.25" to 1.375" thick and are designed to protect against threats that are likely to be encountered in that environment. Typical bullet resistant ratings of UL.752 Level 1 to Level 3 are encountered. But what does a UL.752 Level 1, Level 2 or Level 3 mean and how does it compare to the transparent armor of military applications?

A UL.752 Level 1 material is designed to stop 9mm FMCJ rounds weighing 8.0 grams traveling at a velocity of up to 394 meters/second.

A UL.752 Level 2 material is designed to stop 0.357 Magnum JSP rounds weighing 10.2 grams traveling at a velocity of up to 419 meters/second.

A UL.752 Level 3 material is designed to stop 0.44 Magnum rounds weighing 15.6 grams traveling at a velocity of up to 453 meters/second.

But what does this mean? One of the most important factors in determining whether a bullet resistant structure will stop a ballistics round is how much Kinetic Energy does the ballistics round have.

Using the equation for Kinetic Energy:

Kinetic Energy (Joules) = 1/2 x Mass (Kilograms) x Velocity (meters/second)^2

Calculating the Kinetic Energy for the UL.752 Level 1 ballistics round we find:

Kinetic Energy = 1/2 x 0.008 x 394 x 394 = 620 Joules

For the three UL.752 Levels we get:

Level 1 620 Joules

Level 2 895 Joules

Level 3 1600 Joules

We can see as the weight and the velocity of the round increase the Kinetic Energy of the round increases. The bullet resistant material needs to be able to resist a larger amount of Kinetic Energy.

We can now look at the military grades to compare the amount of Kinetic Energy they are designed to stop. Military grades of transparent armor are composed of multiple layers of glass and polycarbonate. The glass can be of various types. In some cases advanced materials such as Spinel and ALON are also used. Often the structures can be many inches thick.

For US military grades a standard known as ATPD.2352 is used. The different rounds that the materials must stop is listed but the velocities are classified. The fact that the velocities are classified makes it difficult to calculate the required Kinetic Energy that must be absorbed; it would be possible to take an educated guess at the velocities, but for the purposes of this blog post, we do not need to do this is we can use the NATO standard AEP55 STANAG 4549 Volume 1.

STANAG 4549 has 5 protection levels for Light Armored Vehicles. For the purposes of the discussion on transparent armor we will just look at Levels 1 and 4.

Level 1 material is designed to stop a 7.62 mm x 51 NATO ball round weighing 9.65 grams traveling at 833 meters/second.

Level 4 material is designed to stop a 14.5 mm x 114 API/B32 round weighing 64 grams traveling at 911 meters/second.

A Level 1 round has a Kinetic Energy of 3,348 Joules

A Level 4 round has a Kinetic Energy of 26,557 Joules

You can see that the energy that a UL.752 Level 1 material needs to stop is over 40 times less than a STANAG 4549 Level 4 material. The reason for this difference is that the type of ballistics rounds likely to be encountered at a convenience store are likely to be very different from those encountered by the military. Indeed the deterrence factor of bullet resistance glass in commercial applications should not be underestimated.

It should be noted that this discussion is very much a simplification and is only meant to compare the Kinetic Energy of the different rounds used for the different tests. There are a number of parameters that have not been discussed in this blog post such as the multi shot spacing and the shape of the round.

Variable Message Signs (VMS) and Polycarbonate

Over recent months we have had a large number of customer contact us regarding Variable Message Signs (VMS), also known as Dynamic Message Signs (DMS), and the use of Polycarbonate for these signs. These signs are often used as traffic signs to warn drivers or give special information.

The signs often consist of a bank of either yellow or red LEDs behind a protective Polycarbonate front shield. The Polycarbonate is used to protect the sign against impact damage and environmental conditions.

Most of the questions that we get asked relate to a technical standard such as the European Standard EN.12966 for VMS. The main concern relates to the test, which simulates reflection of sunlight when the sun is at a low angle in the sky (5 or 10 degrees). In this situation, the sun is reflected off the Polycarbonate shield to the driver and partially obscures the light coming from the LEDs, making the sign difficult to read.

The sign can be made easier to read by either reducing the reflection of the sunlight or increasing the amount of LED light transmitted through the sheet – either by increasing the LED brightness or increasing the light transmission of the Polycarbonate sheet.

The test apparatus used for EN.12966 is shown in the picture accompanying this blog post [Please click on the picture to enlarge]. The principal of reducing reflection and increasing transmission is the same as that discussed in our previous blog posts with the exception that we are not concerned with the entire visible spectrum. We are specifically concerned with how the Polycarbonate interacts with the Yellow LEDS (wavelength 635 nm) and the Red LEDs (wavelength 590-595 nm) for the vast majority of VMS.

The problem that most VMS manufacturers have experienced is that they frequently buy general purpose Polycarbonate sheet, that has not been optimized for VMS, from distributors or manufacturers that are not aware of the options available. Much of this material has been produced with the idea of minimizing the production cost; as a result there is often large amounts of second grade (regrind) material in the product. As discussed in our previous blog posts, this regrind has the effect of lowering the transmission across the visible spectrum and in particular in the yellow region of the spectrum used by the yellow LEDs of VMS.

The first method improving the visibility of VMS signs in low sunlight is therefore to use an optical grade of Polycarbonate that has been design for VMS use, such as grades offered by HighLine Polycarbonate. The next method is to reduce the reflection and increase the transmission by the use of specially designed coatings. The added advantage of these coatings is that they improve the UV and weather resistant performance of the Polycarbonate, preventing the material from yellowing over time, which would also reduce the transmission in the yellow part of the spectrum. The coatings also add scratch resistance to the sheet, which is important in a road traffic environment.

The following table shows the effect of using a high quality VMS Polycarbonate and using an anti-reflective hard coat. The sheet used is 3mm / 0.118” thick.

Yellow LED Transmission

Uncoated GP Polycarbonate (*) 83.8%

Uncoated VMS Polycarbonate 89.0%

VMS Polycarbonate with anti-reflective hard coat 91.0%

VMS Polycarbonate with anti-reflective hard coat outside and optical coating inside 93.6%

Red LED Transmission

Uncoated GP Polycarbonate (*) 86.0%

Uncoated VMS Polycarbonate 89.7%

VMS Polycarbonate with anti-reflective hard coat 92.0%

VMS Polycarbonate with anti-reflective hard coat outside and optical coating inside 95.5%

[* the GP Polycarbonate was purchased from a distributor and was produced by a major manufacturer as their standard product].

For Yellow LEDs it is therefore possible to increase the transmission by 8.6% [91.0/83.8 = 8.6% increase] by using a properly designed Polycarbonate with an anti-reflective hard coat, for Red LEDs the increase is 7.0% [92.0/86.0 = 7.0% increase].

For both color LEDs the anti-reflective hard coat is also able to reduce the reflection by 25%.

The combination of the increase in transmission and the reduction in reflection significantly increases the readability of the signs in sunlight.

A further option to improve the performance is to use an advanced optical anti-reflective on the inside surface. The use of the advanced optical coatings is not recommended for the outside surface, as they are not suited to use in a dusty and dirty roadside environment. By using these materials on the inside surface the transmission for yellow LEDs rises to 93.6% and the transmission for red LEDs rises to 95.5%.

These figures give an increase in transmission of 11.6% for yellow LEDs and 11.0% for Red LEDs. They also reduce the reflection by 56%. One question that has not yet been completely answered is whether the additional cost of an optical grade anti-reflective is justified by the performance advantage over an anti-reflective hard coat.

The other option for VMS is to use an anti-glare hard coat. At the moment we are investigating the performance of these materials in this application. Anti-glare materials are different from anti-reflective materials in that they scatter the light to reduce reflection; so while you can reduce reflection you also significantly lower the transmission and the clarity of the sign. It remains to be determined whether the loss in transmission is acceptable. At the moment we are very reluctant to recommend anti-glare coatings for VMS applications even though we are able to provide anti-glare coatings.

To summarize, for VMS signs it is important to use a Polycarbonate sheet that has been designed for VMS applications rather than use general purpose Polycarbonate sheet. With an anti-reflective hard coat the transmission can be increased 7.0% for red LEDs and 8.5% for yellow LEDs and the reflection can also be reduced 25%.

Sheet - conversion between weight and area

A short time ago we wrote a blog post about determining how an increase in resin price would affect the sheet price. The calculation involved converting a $ per pound price into a $ per square foot price.

To assist Polycarbonate (and other Polymer) sheet users with this calculation, we have put a simple spreadsheet on our website. This spreadsheet is available to be downloaded and shared. We just ask users not to remove the logo or the disclaimer.

The spreadsheet includes three simple calculations:

1) Given the dimensions of a sheet it allows the user to calculate the sheet weight.

2) Given the dimensions of a sheet and the price in $/lb, it allows the user to calculate the price in $/sqft.

3) Given the dimensions of a sheet and the price in $/sqft, it allows the user to calculate the price in $/lb.

We hope that the spreadsheet is useful and we intend to keep it updated with any feedback and comments that we receive.

Self-repairing coating video

Many people have asked us about our self-repairing coating, but it is only when they have seen it in action that they become really excited. We have therefore put together a short video clip so that you can see how well this coating works.

Please click on the link below to view the video.

watch video



If you need more information about this coating, please contact us at info@highlinepc.com

Polycarbonate and the Power of the Brand name

In this blog post we have moved away from our normal technical content to discuss a subject that has some major implications for the Polycarbonate sheet market place. The question that we will address is: Are powerful brand names still as important as they once were in the plastic sheet market?

There is no doubt that in the past brand names such as Lexan for Polycarbonate and Plexiglas for Acrylic dominated the market. These products were often specified in to projects and could command a premium price from customers due to actual or perceived quality. We decided to look and see if customers were still referring to the brand names or were just looking for Polycarbonate.
As the web is one of the primary means that customers use to find out information about a product, we decided to look at the search interest for "Polycarbonate" and "Lexan" in the United States. In the first graph, we can see that the search interest for Polycarbonate has remained relatively constant since 2004 with some minor decrease due to the economy.



In the second graph we can see that the search interest for Lexan has dropped off significantly and steadily since 2004. As there is still a good interest in Polycarbonate it is possible to conclude that customers are using the generic term Polycarbonate in searches while moving away from the brand name Lexan. Now this information does not mean that Lexan sales have decreased, customers searching for Polycarbonate may still buy Lexan products. However, it does suggest that the brand name value maybe decreasing and if this is the case, the price premium may also be decreasing.

There are of course many events that have happened over time that may explain this trend. During the period being examined, GE Plastics sold the Lexan Polycarbonate part of the operations to SABIC. This transfer of Lexan from a traditional American company to a Saudi Arabian company could certainly affect the branding strategy and the search interest of the brand.



To see if the affect of the brand importance was confined to Lexan, we also decided to look at the other powerhouse brand in the US clear sheet market - Plexiglas. In the graph below we can see how the Plexiglas name has also decreased in search importance. Of course it can be argued that the transfer of the brand from the respected US company Rohm and Haas to a less well known French company Arkema is similar to the situation at Lexan, at least in the US market shown in the graph,



The results of search importance for both Lexan and Plexiglas lead us to question whether brand is as important as it once was in the US clear sheet market. Having questioned this point, there is still no doubt that these names are still valuable branding tools both now and for the foreseeable future. Now that customers, using the internet, are able to evaluate the alternative options more efficiently, the brand name may not be the dominant factor in the purchasing decision.
We would be interested to hear your comments on whether you think brand names are still as important in the plastics industry as they once were and if not, what are the implications?

Lexan is a brand name of SABIC Basic Industries Corp. Plexiglas is a brand name of Arkema Inc.

The Quality of Polycarbonate and Light Transmission

As we explained in a previous blog post, we would typically expect the light transmission of 0.118" one side hard-coated Polycarbonate to be in the range of 90% [with 5.1% reflectance on the uncoated side, 4% reflectance on the coated side and a little internal loss of light transmission due to the internal structure of the Polycarbonate itself]. As the thickness of the Polycarbonate increases, we would expect the internal loss of light transmission to also increase a little.

We were recently asked by a customer to apply an anti-reflective coating to the uncoated side of 0.236" one side hard-coated Polycarbonate. The Polycarbonate was provided by the customer and had been produced by another manufacturer. By applying the anti-reflective coating we were expecting to reduce the reflection on the uncoated side from 5.1% to around 1.0%. We were therefore expecting to increase the overall light transmission from 89-90% to around 94%.

After we had coated the material with the anti-reflective we discovered, to our surprise, that we were only getting a light transmission of 89%. The application of the anti-reflective coating appeared to have failed. We examined our coating process and found no obvious problems. We then decided to test the light transmission of the material before we applied the anti-reflective coating. To our surprise we found that the light transmission was only 84-85% instead of the 90% that we expected. The problem was with the quality of the competitors Polycarbonate and not the anti-reflective coating.

We then measured the reflection on both surfaces and calculated the internal loss of light transmission across the entire visible spectrum. We then repeated this process with our own 0.236" Polycarbonate. We then plotted our the internal loss of light transmission for both materials over the visible spectrum. This plot can be seen in the diagram at the top of the page (for a better view, click on the picture).

The results were shocking.

Over the range of 450-500 nm, our material had an internal loss of light transmission of 2% and the competitors had a loss of 5%

Over the range of 525-575 nm, our material had an internal loss of light transmission of 4% and the competitors had a loss of 7%

Over the range of 650- 750 nm our material had an internal loss of light transmission of 1% and the competitors had a loss of 7%

The end result was that the customer would have been better off buying our HighLine Polycarbonate without an anti-reflective rather than applying an expensive anti-reflective to the competitors material. In the end the customer decided to use our Polycarbonate with an anti-reflective and achieved a light transmission of over 94%.

The lesson to be learned from this recent experience is that not all Polycarbonate sheet is equal. The Polycarbonate sheet from this competitor, who is a major international supplier of Polycarbonate sheet, clearly had a much lower light transmission across the visible spectrum than the Polycarbonate sheet from HighLine Polycarbonate. This lower transmission is caused by inferior resin, use of regrind and the commodity production methods used by some of the large producers. In the vast majority of applications, particularly commodity applications, this loss of light transmission is not important. However, in some quality and high-tech applications, a 6% light transmission loss in the 650-750nm range can be critical. Any application requiring an anti-reflective coating should seriously consider the quality of the base Polycarbonate and should be extremely cautious about buying an off the shelf product from a distributor. Polycarbonate sheet for high quality applications should always be bought directly from the manufacturer so that you can have the material produced specifically for the required application.

All of HighLine Polycarbonate's material is designed for high quality optical applications. If you are using another supplier's material it would be wise to ask for them to provide the light transmission curve for the actual lot number of the sheet you will be receiving. We were certainly surprised by the poor quality of some of the material that is being sold as high quality product.

Bullet Resistant Laminates and Transparent Armor

One statement that we often hear is that Polycarbonate is “bullet-proof”. There are two problems with this statement; the first is that a single Polycarbonate sheet by itself should not be used to stop bullets as it really offers very little protection. The second problem is subtle, materials constructed from Polycarbonate are not bullet-proof but rather bullet-resistant; fire enough shots of high enough caliber and velocity and they will eventually fail.

There has been a need in both the civilian and military sectors to develop glazing materials with bullet-resistance. There are a number of ways of achieving this bullet resistance depending on the required stopping power, cost and weight restrictions. While this article cannot cover all of the options in detail, we will try to give an overview of the options:

1) Perhaps the easiest to make and the cheapest product to buy is specially designed Acrylic sheet that has been specifically tested for bullet resistance. Typically a 1.25” thick Acrylic sheet such as Plexiglas SBAR will stop a 9mm bullet as tested by UL.752 Level 1 test. To get increased stopping power, it is necessary to increase the thickness to 1.375”. At this thickness Plexiglas SBAR product will stop a 0.357” shell as tested by UL.752 Level 2 test. The limitation of this technology is the thickness required to achieve greater stopping power becomes difficult to produce and difficult to install due to the size and the weight.

2) The next option is to use a combination of Acrylic and Polycarbonate. This method is used by Sheffield Plastics, amongst others, in their Hygard BR range. The Acrylic and Polycarbonate are laminated together in various configurations in a vacuum chamber using an interlayer to bond the sheets together. The 9mm UL.752 Level 1 protection is achieved by laminating a ½” acrylic sheet between two layers of 1/8” Polycarbonate. The acrylic sheet absorbs the energy while the more flexible Polycarbonate holds the structure together and prevents shards of Acrylic breaking off and injuring the person behind the window. It can be seen that this type of structure is only 0.75” thick to achieve the Level 1 protection compared to 1.25” for the SBAR product. The 0.357 Level 2 protection is achieved by sandwiching two 3/8” Acrylic sheets between two outer 1/8” Polycarbonate sheets giving a total thickness of 1.0”. A UL.752 Level 3 protection, which uses a Magnum 0.44” has a similar construction that is 1.25” thick. These multiple layer plastic constructions offer greater protection from a thinner material, but at the downside of a greater cost.

3) The next option is to introduce glass. Different companies use different options for the configuration, but nearly all of them use glass bonded to Polycarbonate using inter-layers. Typically one or two sheets of 1/8” Polycarbonate are used. The glass absorbs the energy of the ballistics material and the Polycarbonate holds the material together. Often a sheet of Polycarbonate is put on the inside surface to act as a “spall” layer. This layer prevents shards of glass breaking off and injuring the person behind the glass. This type of option is often used in armoring commercial automobiles for VIPs or diplomats. Using the glass gives additional stopping power, but at the expense of cost and additional weight.

4) The next option moves from the area of commercial ballistics laminates to military transparent armor. These laminates often use multiple layers of glass and multiple layers of Polycarbonate – both as spall shields and internal structures. The completed laminates are often many inches thick and can stop a wide range of military projectiles. Often several different types of glass can be used in a single window to give different properties, the hardness of the glass and the energy absorption of the glass are two such properties. Many of the configurations used by different companies are confidential. The performance of these materials is excellent but they are costly and extremely heavy.

5) The final option is to use advanced materials for the construction of the transparent armor. These materials include ALON, Sapphire and Spinel. Details of these materials can be found on the websites of their manufacturers. While these materials offer exceptional protection they are extremely expensive and often the production process can only produce small parts.

At HighLine Polycarbonate we have a great deal of experience in transparent armor. We have developed a Polycarbonate grade that gives increased performance and stopping power in military laminates compared to other commercial grades of Polycarbonate. We have also developed an advanced thermoplastic sheet, which is more flexible than Polycarbonate and gives a significant improvement in performance when used as a spall shield. The material is lighter than Polycarbonate and is resistant to a wide range of chemicals and solvents, making it ideally suited to use in military transparent armor.

At HighLine Polycarbonate we also are able to include EMI/RFI shielding meshes, transparent conductive heaters, self-repairing coatings, anti-fog coatings, super abrasion resistant coatings, IR shielding and anti-microbial properties – all of which enable our products to be used in the harshest of military environments.

Machine Guards and Chemical Resistance

Polycarbonate has traditionally been used to produce machine guards due to its virtually unbreakable properties. Its good optical properties, ability to form to shapes and its reasonable cost make it an almost perfect choice for the application.

One problem with Polycarbonate in some machine guard applications is that some cleaning chemicals, oils, fuels and greases can attack the surface of the sheet over time. While this chemical attack does not occur in all applications, it can be a severe problem in some industries. This attack of the sheet means that the guards need to be replaced frequently or the user will have to live with optically and sometimes structurally damaged machine guards. Coating the Polycarbonate can offer some degree of protection against chemical attack, but this is not the ideal solution as any scratches that occur in the coating provide sites for attack. Also, using a coating can be a problem if the guards need to be formed, as standard hard-coats will crack. Another problem with Polycarbonate is that over time the surface can become scratched.

Even though Polycarbonate is reasonably inexpensive, the cost of replacing a damaged machine guard can be expensive particularly once the cost of machining, forming, installing the guard and machine downtime is taken into account.

At HighLine Polycarbonate we have developed a new monolithic sheet product known as Grade 5500. This product has been developed especially for applications requiring exceptional chemical resistance. The sheet will not be damaged at all by the vast majority of cleaning chemicals, oils, fuels and greases. The sheet is also much more resistant to scratches than uncoated Polycarbonate, is virtually unbreakable and is lighter than Polycarbonate. The material has also been approved for contact with foodstuffs having an alcohol content of less than 8% according to the FDA specification 21CFR 177.1500 (11).

All of these properties make it the ideal replacement for Polycarbonate sheet in machine guard applications, even in the food processing industry, where Polycarbonate is becoming damaged and needs to be replaced.

For more information about Grade 5500 sheet, contact HighLine Polycarbonate LLC.