When making acrylic display frames, small pieces of acrylic boards are cut off from large pieces of acrylic boards. The common sizes of a normal acrylic plate are 1.22*2.44mm, 1.22*1.83mm, 1.25*2.5mm, 2*3mm, respectively. The thickness ranges from 1mm to 100mm.
In the manufacture of acrylic board, different methods can make different kinds of acrylic. For a variety of acrylic plates on the market, they are roughly divided into three types: cast acrylic, extrusion plate, and recycled version.
1. Cast acrylic
Cast acrylic is a form of poly (methyl methacrylate) (PMMA). It is formed by casting the monomer, methyl methacrylate. Mixed with initiators and possibly other additives into a form or mold. Cast acrylic is high molecular weight, excellent stiffness, strength, and excellent chemical resistance.
This kind of plate is characterized by small batch manufacturing. It has incomparable flexibility in the color system and surface texture effect. The product specifications are complete, practical for a variety of special purposes. All kinds of special plates, such as an abrasive plate, metal effect plate, anti-UV plate and so on, are cast production.
For example，In the production of UV resistant sheet, UV absorbent is added during the process of structural polymerization in the sheet processing. Anti-ultraviolet plate has very high strength and UV function and has an outdoor service life of more than 5 years or even 10 years. The color has been as bright as new during use. Therefore, it is more suitable for processing large size outdoor signboards.
However, the casting plate will encounter the cooling process in the production process, which will produce a large number of industrial wastewater and cause damage to the environment.
2. Extrusion plate:
The extruded acrylic uses granular raw materials and is extruded after dissolution at high temperature. The molecular weight of the extruded acrylic is lower, the mechanical properties are slightly weaker, the flexibility is higher, and the softening time is shorter. This feature is conducive to bending and thermoforming and a variety of rapid vacuum molding. Compared with the cast acrylic, the thickness tolerance is smaller than the cast acrylic.
Extruded acrylic is a large number of automatic production, color and specifications are not easy to adjust. So the diversity of product specifications is limited to a certain extent.
However, mass production can reduce the production cost. The production size specifications have great advantages, can be cut directly according to the production requirements. There is no waste of edge and corner materials.
In addition, because most of the extruded acrylic do not have the anti-ultraviolet function. Their outdoor service life is not the same as the cast acrylic, the extruded acrylic is not suitable as the material of outdoor marking products, only suitable for indoor products such as crystal words or product supports.
3. Recycled acrylic
The recycled acrylic uses recycled acrylic scrap, which is thermally degraded to obtain a regenerated MMA (methyl methacrylate) monomer. Then obtained by chemical polymerization.
In theory, after a strict process, there is no difference in the quality of pure MMA monomers and new synthetic monomers. However, the purity of the degradation monomer produced by the recovered acrylic is not high. After the plate forming, it’s quality performance is very poor. More than half a year will yellowing, it’s easy to crack in the sun. Some bad businesses will use this material to impersonate the above two new acrylics.
Recycled acrylic sheets have specific uses in construction for windows and doors along with lighting components like fluorescent lamps and chandeliers.
How to distinguish between a cast acrylic and extruded acrylic?
The quality of the cast sheet is better than that of the extruded sheet, and the processing range is more durable. However, it is difficult to distinguish between the two in appearance. There are several ways to distinguish the two acrylics:
1. Price differentiation: because the raw materials and processes used in the cast acrylic are higher than the requirements of the extruded acrylic, the cast acrylic is a little more expensive than the extruded acrylic.
2. Thickness tolerance: plate thickness (cast acrylic: 1.8MM-300MM extruded acrylic: 0.5-12MM) cast acrylic thickness tolerance is greater than extruded acrylic tolerance. The thickness of the acrylic sheet plate can be measured and compared using micrometers.
3. Different properties: cast acrylic process performance is high, suitable for all kinds of processes, the surface amorphous point, relatively high transparency. However, the edge and corner of the extruded plate will turn yellow, the surface is easy to produce crystal points (the dust-free workshop can solve this problem), and the technological performance is weak.
4. Fire method: after burning with fire, touch the combustion position, pull the cast acrylic less filament. Extruded acrylic has a large number of filament pull out, casting plate combustion will have obvious burst sound, and extruded acrylic sound is very small.
How to distinguish the recycled board from the recycled plate
1. The transparency of the recycled acrylic is lower than that of the pure new material. The transmittance of the recycled acrylic is less than 86% and the cross section is yellowed.
2. The surface of recycled acrylic hardness is low, easy to scratch, produce a pungent smell during cutting.
3. The quality of the protective film is poor, recycled acrylic easy to age and deteriorate.
4. In thermoforming heating, recycled acrylic is easy to produce bubbles.
5. Recycled acrylic is sensitive to paint ink, prone to craze or cracks.
6. The recycled acrylic bubbles and emits black smoke with a pungent smell when burning.