Acrylic scrap recycle

Acrylic scrap recycle

 

Acrylic

Acrylic, also known as  poly methylmethacrylate (PMMA), is a clear, colorless transparent plastic with a higher melting point, better impact strength, and better weather resistance than polystyrene (PS). It is widely used in many areas like transparency roof, automobile parts, etc. and produced principally through extrusion and casting.

Acrylic scrap

The cell casting process, of sheet manufacture, which consists of two flat glass plates separated by an elastomeric gasket, is generally used for the manufacture of transparent acrylic sheets. In general, the gasket is used only once and has to be removed from the finished product by cutting in order to make the required sheet size. Residual acrylic material sticking around unusable gaskets, generated during cutting step, comprises approximately 10% of total final production, and becomes an industrial waste. Acrylic plastic is not easily recycled and is therefore not collected for recycling in many countries.

Scrap Acrylic is an industrial waste, not only having a significant impact on the environment but also on the cost of production of Acrylic Sheets. Acrylic plastics are not easily biodegradable. Some acrylic plastics could be highly flammable. PMMA scrap with technological additives can, however, be recycled and re extruded to produce new PMMA sheet in spite of its amorphous structure.

 Industrial PMMA scrap can be divided into two groups, pure acrylic plastic scrap   which forms about 20% and reinforced acrylic plastic scrap forming about 80% of the total amount.

Recycling Scrap by Pyrolysis

The process generally consists of heating the acrylic scrap with certain chemicals to a temperature of 4000-4500ºC in a mild steel distillation still. The heating results in the depolymerisation of PMMA to Methyl meth acrylate monomer which is condensed and redistilled to get the pure regenerated monomer. A mixture of the pure monomer and regenerated monomer (generally up to 5%) is then mixed with Benzyl peroxide (catalyst) and heated. After the desired degree of polymerization, the viscous mass is cooled, mixed with colours and poured into molds. It is then heated and dipped in a hot water bath to complete the polymerization process.

 PMMA has also been successfully depolymerised by contacting with molten lead resulting in MMA with a purity of more than 98%, but from an environmental point of view the use of lead many be undesirable.

Recycling Scrap by Melting

It is also claimed that acrylic scrap can be melted in a high temperature furnace after separation and grinding. The molten liquid is put in mold plates and then taken to a pressurized oven for a period of 12 hours, making the acrylic plates again. The acrylic sheets can be used to create various types of products, furniture, decorative items, Car parts etc. It is reported that this is cheaper by 30% than the manufacture of the conventional Acrylic Plates.

Reprocessing of reinforced plastic scrap

Composite plastic scrap (vacuum formed acrylic plastic with glass fibre reinforcement) has low density and thus has to be pre crushed to save transportation and land filling costs.

Reprocessing of problematic plastic scrap (composite plastics) by using mechanical methods like milling by collision in disintegrators, has been tried successfully. For the milling of composite plastic scrap, different disintegrator mills are used for the size reduction of the acrylic plastic constituent and the separation of the glass fibre constituent. Plastic powder with a particle size of about 1–2 mm can be produced by two step milling and 95 mass % of the glass fibre content can be separated by final selective milling. The total amount of separated Glass Fibre particles (GFP) was 45 mass %.  55 mass % of acrylic plastic from the composite plastic scrap (GFP) can be, therefore, reused in the production of polymeric concrete products as reinforcement. Heating up an acrylic plastic material over glass, transition temperature (100 °C), converts the plastic into a rubber-like state, which makes this material ideal for vacuum forming. Continued heating causes thermal degradation of the material instead of melting.

Acrylic powder has found application as a new filler material in the Solid Surface casting technology for producing bathroom washbasins. Commonly, washbasins are made from a composite material consisting of a binder agent (unsaturated polyester resin), a filler material (dolomite powder) and a catalyst agent added to the resin to accelerate hardening. The mixing ratios of the binder agent and the filler material are 25/75 mass %. The traditional filler material, used in the casting technology, is a high-white dolomite filler. Acrylic powder was used to substitute for the high white dolomite filler. The best flow characteristics of the mixture were obtained with 50 mass % of acrylic filler and 50 mass % of matrix, but the best surface quality and hardness after polishing was achieved with a mixture of 66 mass % of the acrylic filler and 34 mass % of the resin matrix. Reprocessed plastics washbasins, produced from the new composite material, increase the wear resistance of the working surface. At the same time, as compared to the dolomite filler, double reduction in weight can be achieved.

Recycled scrap vs. virgin MMA Acrylic sheets – Properties

Concentrations of acrylic waste scrap mixed with the acrylic monomer solution in the range of 4% and 5%, give the viscosity values in the range of 500-1611 cp. which are appropriate for pouring into casting cells and conform to the standard viscosity prescribed for molding.

In experimental studies the acrylic waste scrap did not affect the impact strength and hardness properties of the acrylic cast sheet product although the tensile strength property of the acrylic cast sheet product increased with increasing the amount of acrylic waste. The acrylic waste scrap did not affect the transparency property of the acrylic cast sheet. Acrylic waste scrap affects the UV resistance property but did not affect the heat resistance property. However, the UV resistance property of the acrylic cast sheet product mixed with the acrylic waste scrap can be improved by the addition of UV stabilizer additive, which is usually added to the final product of acrylic cast sheet before sale to customer.

 

Recycled Acrylic Products

Recycled Acrylic products find use in the following application.

  • Construction- Sound proof windows and doors, windows mining masks and telephone both.
  • Medical- baby incubators, medical and surgical devises.
  • Public Goods- Handicrafts, sanitary facilities, cosmetics frames.
  • Surface of instrument Panel and Cover.
  • Lighting- Fluorescent-lamps, chandeliers, street lamps.
  • Advertising –Light boxes, signage, exhibition.
  • Transport – Cars, trains and other vehicles, doors and windows.

 

Advantage Recycling

Reutilization of acrylic scrap in the Acrylic sheet manufacturing process results in a decrease in the environmental impacts and processing costs.  In an experiment carried out at the Pan Asia Industrial Company in Thailand using 16000 Kg. of methyl methacrylate monomer in a batch reactor, 1600 Kg. of scrap was generated and 800 Kg. (5%) of this scrap was recycled. This brought about a 6 to 7 % saving in total costs. In addition it resulted in decrease in pollutants and national resource consumption as follows-

Environmental Aspects                                                      Unit

Raw Material (Acrylic Monomer)                                       800 kg/day

Coal                                                                                        208 kg/day

Oil                                                                                           472 kg/day

Natural Gas                                                                           576 kg/day

Co2                                                                                         2640 kg/day

Nox                                                                                         1208 kg/day

Sox                                                                                         14.4 kg/day

Clty                                                                                         10.4 kg/day

Dust                                                                                        2.5 kg/day

BOD                                                                                       281600 mg/day

Land Conversion                                                                 32 m2/800 kg          

 

Filed in: Wealth from Waste

7 Responses to “Acrylic scrap recycle”

  1. August 25, 2011 at 8:42 am #

    Dear Sir,
    kindly say that we have 55 molds for washbasin,sink etc we want to make acrylic modified washbasin, sink etc to used pmma powder. so we want to your cooperation to make this products .pl send complete detail.
    thanking you
    KL SAKHRANI
    LUCKY & COMPANY
    761,SARDHUL SINGH KI NAAL
    GANGORI BAZAR
    JAIPUR
    9785645930
    luckytrading99@yahoo.com

  2. ALLAN NAIDOO
    March 16, 2012 at 1:11 pm #

    Dear Sakhrani,

    My name is Allan Naidoo, i am looking to export recycled cast acrylic material at a cost

  3. Maxim Timin
    April 26, 2012 at 6:35 am #

    Dear Mr. Sakhrani,

    I am very interested in the fields of application of PMMA scraps (either cast or extrusion) and in methods of manufacturing various acrylic articles using the above scraps. Can you, please, give me recommendations or advices concerning such technologies?
    I will be very obliged to you for your help.

    Maxim Timin
    Russia

  4. Faisal
    May 22, 2012 at 6:17 pm #

    Dear!

    Regarding recycling of acrylic sheet scrap, please advice the name of the oil (brown or black colored oil) which is produced after melting the acrylic scrap in furnace. First step of recycling.

    Thanks,
    Faisal.

  5. Danish Mianoor
    September 27, 2012 at 9:01 am #

    Dear ,
    I am the manufacturer of cast acrylic plastic sheet in Pakistan .. The nam of my company is Prince Poly Impact .. I have the both procedure of recycling n fresh .. We are abt manufacturing sheets from last 25 years but due to some reasons we cant modify our systems .. So the thing which i want to ask from u is that when we recycle scrap we get black oil .. than we use castic n others agents to make it transparent .. but one thing i cannot understand that these days at the time of washing we are getting some powder while washing the black oil .. so i cannot understand that what is that white powder coming while washing .. n other thing is that our market of pakistan need cheaper thing .. so u know that fresh monomer is abt 2100 to 2200 $ per ton nowadays n scrap is abt 1000 to 1100 $ per ton .. so is there any cheap agent which i can mix with monomer to reduce the cost and which should can be easily soluble in monomer .. and one thing more is that in recyle procedure i m getting abt not more than 70% recovery after washing .. so is there any procedure through which i can get more recovery from scrap .. thanx
    Best Regards
    Danish Mianoor

  6. anuj
    February 7, 2013 at 1:40 pm #

    Dear ,
    I am the manufacturer of cast acrylic plastic sheet in india.. The nam of my company is metro plastic .. I have the both procedure of recycling n fresh .. We are abt manufacturing sheets from last 25 years but due to some reasons we cant modify our systems .. So the thing which i want to ask from u is that when we recycle scrap we get black oil .. than we use castic n others agents to make it transparent .. but one thing i cannot understand that these days at the time of washing we are getting some powder while washing the black oil .. so i cannot understand that what is that white powder coming while washing .. n other thing is that our market of pakistan need cheaper thing .. so u know that fresh monomer is abt 2100 to 2200 $ per ton nowadays n scrap is abt 1000 to 1100 $ per ton .. so is there any cheap agent which i can mix with monomer to reduce the cost and which should can be easily soluble in monomer .. and one thing more is that in recyle procedure i m getting abt not more than 70% recovery after washing .. so is there any procedure through which i can get more recovery from scrap .. thanx
    Best Regards
    anuj gupta

  7. April 5, 2013 at 9:00 am #

    My name is Ceruti Mattia, I’m working as product manager for polymerization additives, anyone would be interested in a product able to stabilize the PMMA syrup generated from the scrap?

    I believe the syrup will be much more reactive than fresh MMA, I’m looking for some producer willing to test this possible application.

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