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Acrylic material
Published:2019-04-12 10:18:04    Text Size:【BIG】【MEDIUM】【SMALL
Summary:High transparency,widely used for crafts,display,advertising products
Performance characteristics
characteristic
1, with crystal-like transparency, light transmittance of more than 92%, soft light, clear vision, acrylic dyed with dye has a good color effect.
2. Acrylic sheet has excellent weather resistance, high surface hardness and surface gloss, and good high temperature performance.
3, acrylic sheet has good processing properties, both thermoforming and mechanical processing.
4, transparent acrylic sheet has a light transmittance comparable to glass, but the density is only half of the glass. In addition, it is not as fragile as glass, and even if it is destroyed, it does not form sharp fragments like glass.
5. The abrasion resistance of the acrylic sheet is close to that of aluminum, the stability is good, and it is resistant to corrosion by various chemicals.
6, acrylic sheet has good printability and sprayability, using appropriate printing and spraying process, can give acrylic glass products the ideal surface decoration effect.
7. Flame resistance: It is not self-igniting but it is flammable and does not have self-extinguishing properties.
Characteristics
1, hardness
Hardness is one of the parameters that best reflects the production process and technology of pouring acrylic sheet, and is an important part of quality control. The hardness can reflect the purity of the raw material PMMA, the weather resistance of the sheet, and the high temperature resistance. The hardness directly affects whether the sheet will shrink and bend, and whether the surface will be cracked during processing. Hardness is one of the hard and good indicators for judging the quality of acrylic sheets. The average Damoc hardness value is about 8 or 9 degrees.
2, thickness (acrylic tolerance)
Acrylic sheet thickness has acrylic tolerances, so the control of acrylic tolerance is an important manifestation of quality management and production technology. Acrylic production has an international standard ISO7823
Tolerance requirements for cast-in-place plates: tolerance = ± (0.4 + 0.1 x thickness)
Tolerance requirements for extruded plates: tolerance = < 3 mm thickness: ± 10 % > 3 mm thickness: ± 5 %
3, transparency / whiteness
Strict raw material selection, advanced formulation follow-up and modern production processes ensure excellent transparency and whiteness. After the flame is polished, it is crystal clear.
Attributes
Mechanical properties
Polymethyl methacrylate has good comprehensive mechanical properties and is in the forefront of general-purpose plastics. The tensile strength, tensile strength, compression and other strengths are higher than that of polyolefins, and higher than that of polystyrene and polyvinyl chloride. The impact toughness is poor. But also slightly better than polystyrene. The cast bulk polymethyl methacrylate sheet (such as aerospace plexiglass sheet) has higher mechanical properties such as stretching, bending and compression, and can reach the level of engineering plastics such as polyamide and polycarbonate.
In general, polymethyl methacrylate has a tensile strength of 50-77 MPa and a flexural strength of 90-130 MPa. The upper limit of these performance data has reached or exceeded that of some engineering plastics. Its elongation at break is only
2%-3%, so the mechanical properties are basically hard and brittle plastic, and have a notch sensitivity, easy to crack under stress, but the fracture is not as sharp as polystyrene and ordinary inorganic glass. 40 ° C is a secondary transition temperature, which is equivalent to the temperature at which the side methyl group starts to move. When the temperature exceeds 40 ° C, the toughness and ductility of the material are improved. Polymethyl methacrylate has a low surface hardness and is easily scratched.
The strength of polymethyl methacrylate is related to the stress action time, and the strength decreases as the action time increases. The mechanical properties of the stretched oriented polymethyl methacrylate (oriented plexiglass) are significantly improved, and the notch sensitivity is also improved.
Polymethyl methacrylate has low heat resistance. Although its glass transition temperature reaches 104 ° C, the maximum continuous use temperature varies between 65 ° C and 95 ° C depending on the working conditions. The heat distortion temperature is about 96. °C (1.18MPa), Vicat softening point of about 113 °C. The heat resistance can be improved by a method in which a monomer is copolymerized with propylene methacrylate or ethylene glycol diacrylate. Polymethyl methacrylate also has poor cold resistance, and the embrittlement temperature is about 9.2 °C. Polymethyl methacrylate has moderate thermal stability, superior to polyvinyl chloride and polyoxymethylene, but less than polyolefin and polystyrene. The thermal decomposition temperature is slightly higher than 270 ° C, and its flow temperature is about 160 ° C. There is a wide range of melt processing temperatures.
The thermal conductivity and specific heat capacity of polymethyl methacrylate are moderate in plastics, 0.19W/M.K and 1464J/Kg.K, respectively.
Electrical performance
Polymethyl methacrylate has less electrical properties than non-polar plastics such as polyolefins and polystyrene due to the polar methyl ester group at the side of the main chain. The polarity of the methyl ester group is not too large, and the polymethyl methacrylate still has good dielectric and electrical insulating properties. It is worth noting that polymethyl methacrylate and even the entire acrylic plastic have excellent arc resistance. Under the action of arc, the surface does not produce carbonized conductive paths and arc track phenomena. 20 ° C is a secondary transition temperature, corresponding to the temperature at which the side methyl ester group begins to move, below 20 ° C, the side methyl ester group is in a frozen state, and the electrical properties of the material are increased above 20 ° C.
Solvent resistance
Polymethyl methacrylate can withstand relatively rare inorganic acids, but concentrated inorganic acids can erode it and can be resistant to alkalis, but warm sodium hydroxide and potassium hydroxide can etch it and can withstand salt. And oils, oil-resistant hydrocarbons, insoluble in water, methanol, glycerin, etc., but can absorb alcohol swelling, and cause stress cracking, not resistant to ketones, chlorinated hydrocarbons and aromatic hydrocarbons. Its solubility parameter is about 18.8 (J / CM3) 1/2, soluble in many chlorinated hydrocarbons and aromatic hydrocarbons, such as dichloroethane, trichloroethylene, chloroform, toluene, etc., vinyl acetate and acetone can also make it Dissolved.
Polymethyl methacrylate has good resistance to gases such as ozone and sulfur dioxide.
Weather resistance
Polymethyl methacrylate has excellent weathering resistance. The sample has been subjected to natural aging test for 4 years. The weight change, tensile strength and light transmittance are slightly decreased, the color is slightly yellowish, and the anti-silver grain is decreased. Obviously, the impact strength is also slightly improved, and other physical properties are almost unchanged.
Flammability
Polymethyl methacrylate is easily burned with a limiting oxygen index of only 17.3.
Main classification
Type of plexiglass (acrylic) sheet
Acrylic sheet
Acrylic products
Acrylic products (5 photos)
 There are many types of materials.
Common boards are: transparent board, dyed transparent board, milk white board, color board;
The special plates are: bathroom board, cloud board, mirror panel, cloth board, hollow board, impact board, flame retardant board, super wear board, surface tread board, frosted board, pearl board, metal effect board, etc.
Different performances, different colors and visual effects to meet the ever-changing requirements.
1. Acrylic sheet is divided into casting board and extrusion board according to the production process. According to the transmittance, it can be divided into transparent board, translucent board (including transparent board of dyeing board), color board (including black and white and color board); Impact plate, anti-ultraviolet plate, ordinary plate and special plate such as high impact plate, flame retardant plate, frosted plate, metal effect plate, high wear plate, light guide plate, etc.
A: Casting plate: high molecular weight, excellent stiffness, strength and excellent chemical resistance. Therefore, it is more suitable for processing large-sized signboards, which is relatively long in the softening process. This sheet is characterized by small batch processing, incomparable flexibility in color system and surface texture effects, and complete product specifications for a variety of special applications.
B: Extrusion plate: Compared with the cast plate, the extruded plate has a lower molecular weight, a slightly weaker mechanical property, and a higher flexibility. However, this feature facilitates bending and thermoforming processes with a shorter softening time. It is advantageous for various rapid vacuum forming when dealing with large-sized sheets. At the same time, the thickness tolerance of the extruded plate is smaller than that of the cast plate. Since the extrusion plate is mass-produced in an automated manner, color and specifications are inconvenient to be conditioned, so the product specification diversity is limited.
2, Acrylic also has a kind of recycled material recycling board is the use of recycled acrylic trim, after thermal degradation to obtain regenerated MMA (methyl methacrylate) monomer, and then obtained by chemical polymerization. After a rigorous process, the pure MMA monomer can be regained, and there is no difference in quality from the new synthetic monomer. However, the degradation monomer produced is not high in purity, and its quality and performance are poor after the sheet is formed.
Summary: The extruded plate is made of granular raw materials, which are extruded after high temperature dissolution, and the cast plate is directly cast by MMA monomer (liquid). Although the shape of the extruded plate is relatively smooth and smooth, it is formed during the formation of the granular material. To complete the aggregation. When processed into sheet metal, its structure and performance are weak, and it is not suitable as a material for outdoor signage products. It is only suitable for indoor products such as crystal characters or product holders.
In addition, since most of the extruded plates do not have the function of preventing ultraviolet rays, the life of the outdoor use is not the same as that of the cast plate, the color will gradually fade and it will be easily embrittled until it is broken. The cast plate is structured during the processing of the sheet, with the addition of UV absorbers, which have extremely high strength and UV function. The outdoor service life is more than 5 years and even 10 years. The color is always bright and new during use.
Process characteristics
1. Polymethyl methacrylate contains a polar side methyl group, which has obvious hygroscopicity, and the water absorption rate is generally 0.3%-0.4%. It must be dried before molding, and the drying condition is drying at 80°C-85°C for 4-5h. .
2. Polymethyl methacrylate has obvious non-Newtonian fluid properties in the temperature range of molding processing. The melt viscosity decreases with the increase of shear rate, and the melt viscosity is also sensitive to temperature changes. Therefore, for the molding process of polymethyl methacrylate, increasing the molding pressure and temperature can significantly reduce the melt viscosity and achieve better fluidity.
3. The temperature at which polymethyl methacrylate starts to flow is about 160 ° C, and the temperature at which decomposition begins is higher than 270 ° C, and has a wide processing temperature interval.
4. Polymethyl methacrylate has a high melt viscosity and a fast cooling rate, and the product is prone to internal stress. Therefore, the control of the process conditions is strict during molding, and post-treatment is also required after the product is formed.
5, polymethyl methacrylate is an amorphous polymer, the shrinkage rate and its range of variation are small, generally about 0.5% -0.8%, which is conducive to the formation of plastic parts with higher dimensional accuracy.
6. Polymethyl methacrylate has excellent cutting performance, and its profiles can be easily machined to various required sizes.
Processing technology
Polymethyl methacrylate can be processed by casting, injection molding, extrusion, thermoforming, and the like.
Cast molding
Cast molding is used to form profiles of plexiglass sheets, rods, etc., that is, forming profiles by bulk polymerization. The cast product needs to be post-treated, and the post-treatment conditions are 2 h at 60 ° C and 2 h at 120 ° C.
Injection molding
Injection molding using pellets obtained by suspension polymerization, formed in ordinary
Acrylic stick
Acrylic stick
Performed on a plunger or screw injection molding machine. Table 1 shows typical process conditions for polymethyl methacrylate injection molding.
Injection molding products also need post-treatment to eliminate internal stress. The treatment is carried out in a 70-80 °C hot air circulation drying oven. The treatment time depends on the thickness of the product, and generally takes about 4 hours.
Extrusion
Polymethyl methacrylate can also be formed by extrusion molding, using granules produced by suspension polymerization to prepare plexiglass sheets, rods, tubes, sheets, etc., but the profiles thus prepared, especially the sheets, due to the small molecular weight of the polymer, The mechanical properties, heat resistance and solvent resistance are not as good as cast molding profiles, and the advantages are high production efficiency, especially for pipes and other casting molds. Profiles that are difficult to manufacture. Extrusion can be carried out with a single or double-stage vented extruder with a screw length to diameter ratio of 20-25. Table 2 is a typical process condition for extrusion molding.
Thermoforming
Thermoforming is a process of forming a plexiglass sheet or sheet into articles of various sizes and shapes. The blank cut into the required size is clamped on the mold frame, heated to soften it, and then pressed to make it close to the mold surface. The shape is the same as that of the profile, and the product is finished by trimming the edge after cooling and setting. The pressurization may be by vacuum drawing or by direct pressing of a punch having a profile. The thermoforming temperature can be referred to the temperature range recommended in Table 3. When adopting a rapid vacuum low draft forming product, it is preferable to adopt a near-lower limit temperature and a deep drawing product having a complicated forming shape, and it is preferable to adopt a near upper limit temperature, and a normal temperature is generally used.

Carving and cutting


Acrylic crafts
Mainly for hollowing and engraving of already formed acrylic or colored acrylic materials. Ordinary laser engraving and cutting machines can meet the engraving and hollowing requirements of most acrylic products.
The main purpose
Evowe acrylic texture board
Evowe acrylic texture board
PMMA is a polymer obtained by polymerizing acrylic acid and its esters, collectively referred to as acrylic resin. The corresponding plastics are collectively referred to as polyacrylic plastics, of which polymethyl methacrylate is the most widely used. Polymethyl methacrylate, abbreviated as PMMA, commonly known as plexiglass, is by far the most excellent synthetic transparent material.
PMMA has the advantages of light weight, low cost and easy molding. Its molding methods include casting, injection molding, machining, and thermoforming. In particular, injection molding can be mass-produced, with simple process and low cost. Therefore, its application is increasingly widespread, it is widely used in instrumentation parts, automotive lights, optical lenses, transparent pipes and so on.
advantage
Acrylic is the best new material that can be used to make sanitary ware after ceramics. Compared with traditional ceramic materials, acrylic has the following advantages in addition to unparalleled high brightness: good toughness and not easy to break; strong repairability, just use a soft foam to remove the toothpaste to wipe the sanitary ware; soft texture, winter There is no sense of cold and biting; the color is bright, which can satisfy the individual pursuit of different tastes. Acrylic basins, bathtubs, and toilets are not only beautiful in style, durable, but also environmentally friendly. Their radiation levels are similar to those of the human body. Acrylic sanitary ware first appeared in the United States and has occupied more than 70% of the entire international market.
Disadvantage
Because acrylic production is difficult and costly, there are many low-cost and low-cost substitutes on the market. These substitutes are also known as "acrylic" and are actually ordinary organic boards or composite boards (also known as sandwich panels). Ordinary organic plates are cast with common plexiglass cracking materials and pigments. The surface hardness is low and easy to fade. After polishing with fine sand, the polishing effect is poor. The composite board has only a thin layer of acrylic on the surface, and the middle is ABS plastic, which is easily delaminated by the expansion and contraction during use. True and false acrylic, which can be identified from the subtle chromatic aberration and polishing effect of the sheet section
Acrylic is widely used for test racks and patch trays.
Application field
1, building applications: window, soundproof doors and windows, lighting hood, telephone booth and so on.
2, advertising applications: light boxes, signs, signs, display racks and so on.
3, traffic applications: trains, cars and other vehicle doors and windows.
4, medical applications: baby incubators, all kinds of surgical medical equipment, civilian supplies: bathroom facilities, crafts, cosmetics, stents, aquariums and so on.
5, industrial applications: instrument surface board and cover.
6, lighting applications: fluorescent lamps, chandeliers, street lamp covers, and so on.
Application areas: hotels, shopping malls, office buildings, clubs, villas, museums, medical, education, catering, exhibitions, etc.
Application areas: ceilings, integrated ceilings, partitions, screens, sliding doors, transparent walls, hotel furniture, office furniture, bar counters, lighting, chandeliers, signs, signs, floors, landscapes, etc.

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