PC polycarbonate plastic sheets are outstanding for their impact strength and high temperature resistance. Because of this, they are often employed in construction sector applications, such as coatings, coverings and anti-vandal town furniture.
Characteristics :
- Excellent transparency and surface brightness.
- High heat resistance.
- Excellent impact strength.
- Thermoformable.
- Intermediate chemical resistance.
- Medium fire performance.
- Reduce noise transmission.
- Recyclable.
Possible Applications :
- Displays, showcases and other publicity material at sales points
- Machinery protection
- Moulded pieces
- Dispensing and recreational machines
- Signs and signals
- Protective shields
- Security glazing
- Construction components
- Town furniture (anti-vandal)
- Walls and ceilings
- Covering panels
- Warehouse panels
- Caravan bodywork panels
Technical :
- PC sheets can withstand temperatures of up to 120° C depending on the application.
- PC sheets can be sawn, edged and drilled without any burring. Crack-free holes can be easily made. They can be milled with conventional milling machines. A good clamping system is required. Laser cutting is not recommended.
- ​PC sheets are not protected against sunlight. However, the actual material itself possesses a certain resistance to outside weather so that it can be used in exterior applications in locations where sunlight is of low intensity and does not permanently fall on the sheets. When used in exterior applications, the protective film must be removed immediately, since exposure to sunlight can cause permanent adhesion to the sheet.
- Light Transmission : 87-91%
- The sheets should be cleaned with a solution of warm water with a little neutral soap and rinsed with water employing a very soft sponge or chamois leather.
Cutting / Sawing :
The common types of saws employed in wood or metal carpentry provide good results when sawing PC sheets: disc, band, sabre, jigsaw, hewing and handsaw. Disc or band saws produce the best edges and can perform almost all cutting operations.
Blade shape plays an important role in sawing plastics. It is recommended to employ a band saw with separated teeth because the empty space will facilitate the exit of the cut chips. The best results are obtained using teeth without any inclination and also somewhat jumped. To prevent the plastic from cracking or melting, the blade must be very sharp and the guide should very close to the cut to prevent vibration.
Polishing :
The sheet edges can be buffed using buffing paste, first with a rigid fabric disc and then with a soft cloth to produce the final finish.
Drilling :
PC sheets can be drilled quite easily with a normal stand drill or even with a hand-drill using clean, sharp drill bits. Drill bits designed for use with plastics are recommended. It is occasionally possible to use ordinary drill bits, but they should be sharpened to reduce the depth or cutting angle. During the drilling operation, the sheet must be firmly held, but avoiding excessive pressure at the same time. The hole must be larger than the screw to allow for thermal dilation and contraction.
There must be a separation between the edge and the hole of at least twice the hold diameter. Speeds of up to 1,750 rpm are preferred for small drill holes and for larger holes, whereas speeds as low as 350 rpm are advised. The use of compressed air is recommended to prevent overheating, especially in cases where sheet thicknesses exceed 5 mm.
Glueing :
Among the recommended adhesives are those based on solvents, hot melt, silicone, two-component polyurethane based, two-component epoxy based and adhesive tapes.
The following should be taken into considerations when selecting an adhesive:
- Chemical compatibility with the PC sheets
- Aesthetics of the finished joint
- Dilation and contraction with temperature changes
- Fragility, rigidity and flexibility
- Alterability with respect to outside weather, where applicable - Duration/useful lifetime
- Adhesive strength (adherence to the plastic)
- Final usage requirements
The surfaces to be glued should be cleaned with a soft cloth and alcohol to eliminate all dirt and grease.
For perfect gluing of the surfaces to be joined, they must fit together well (without exerting force and without leaving any cavities) and should also be smooth and unpolished.
Some adhesives can contract on drying. This effect can be compensated by cutting the joint at an angle, thus leaving space to be filled with a slight excess of adhesive.
Thermoforming
There are various thermoforming techniques that can be applied to PC sheets in order to obtain the desired shape once heated, using mechanical force, compressed air or a vacuum. Moulds can be made of plaster, water-cooled steel, cast aluminium or other materials, such as wood or epoxy.
Pre-drying is necessary in a forced air circulation oven at 120 °C because moisture can produce bubbles or other problems in surface appearance. Drying time depends on sheet thickness.
All PC products use film to protect the surface from possible damage during production and transport. This protective film is not prepared to withstand high temperatures and must be removed prior to pre-drying, thermoforming or hot-bending.
Vacuum moulding
The thermoforming temperature must be between 185 and 205 °C, depending on sheet thickness.
Drop-moulding
Temperature between 145 and 160°C.
Bending
Hot-bending
Using two electric element heaters on both sides, (top and bottom), it becomes possible to bend at more precise angles. When the sheet reaches the correct temperature (above 155oC) a slight resistance will be noted to folding, this is when the sheet is easily bent.
If it is attempted to bend the sheet before it has been sufficiently heated, cracks will appear that could lead to breakage. If, on the other hand, the sheet is over-heated, bubbles might appear along the section that is to be bent.
All PC products use film to protect the surface from possible damage during production and transport. This protective film is not prepared to withstand high temperatures and must be removed prior to pre-drying, thermoforming or hot-bending.
Cold bending
The maximum recommended angle is 90o for sheets having a thickness of less than 6 mm. This angle becomes 135o for sheets with a thickness greater than 135o. It is often necessary to bend in excess in order to achieve the desired angle.
Decoration
Printing
PC sheets can be printed using most printing methods.
Painting
PC can be painted without surface treatment. The print film should be removed just prior to printing to prevent the surface from damage.
